url,verdict,source,claim,headline,verdict_detail,key_takeaway,full_claim,references,review
https://science.feedback.org/review/pyramid-shaped-peaks-antarctica-naturally-carved-by-glaciers-not-constructed-by-ancient-civilization/,Inaccurate,"Facebook, YouTube, TikTok, X/Twitter, 2024-03-20","Ancient civilizations once inhabited Antarctica, as shown by the pyramids there, but the continent’s position and climate rapidly changed due to ‘tectonics and pole shift’.",,"Factually inaccurate: There is no evidence of ancient civilizations or pyramids in Antarctica. The pyramid-shaped landform shown in recent social media videos is called a ‘horn’ or ‘pyramidal peak’ and forms naturally as glaciers carve (i.e., erode) different rock faces. There is also no evidence for a rapid shift in the climate or position of Antarctica on Earth; studies show that Antarctica slowly drifted over millions of years through tectonic plate movements.","The rocky pyramid-shaped feature in Antarctica is a natural landform called a ‘horn’ or ‘pyramidal peak’. These peaks form when three or four intersecting glaciers carve out mountain faces in different directions, thus making a horn or pyramidal shape. They are common in Antarctica and found in many other places on Earth. Scientific evidence shows that Antarctica slowly drifted to its current position over millions of years through tectonic plate movement; not a sudden shift of the poles or crust.","Thawing ice in Antarctica is revealing pyramids and other remnants of an ancient civilization. Antarctica quickly moved across Earth into its current position through plate tectonics and pole shift, causing Antarctica’s surface to flash-freeze. ","1- Hess (2016) McKnight’s Physical Geography: A Landscape Appreciation. 2 – Sugden et al. (2017) The million-year evolution of the glacial trimline in the southernmost Ellsworth Mountains, Antarctica. Earth and Planetary Science Letters. 3 – Palin and Santosh (2021) Plate tectonics: What, where, why, and when?. Gondwana Research. 4 – Zahirovic et al. (2015) Tectonic speed limits from plate kinematic reconstructions. Earth and Planetary Science Letters. 5 – Kulakov et al. (2021) Jurassic fast polar shift rejected by a new high-quality paleomagnetic pole from southwest Greenland. Gondwana Research. 6 – Moulin et al. (2011) An attempt to constrain the age, duration, and eruptive history of the Karoo flood basalt: Naude’s Nek section (South Africa). Journal of Geophysical Research: Solid Earth. 7 – Svensen (2018) Gondwana Large Igneous Provinces: plate reconstructions, volcanic basins and sill volumes. Geological Society, London, Special Publications.","On 20 March 2024, a video on YouTube claimed that ‘Antarctica has pyramids from an ancient civilization’, and that ‘the continent’s surface flash-froze as it rapidly shifted on Earth‘. This video has gathered over 3.4 million views, and in recent months it has been clipped and shared on TikTok, Facebook, and X/Twitter. A quick search on TikTok turns up many of these clips and dozens of similar videos speculating about these alleged ‘pyramids’ and the history of Antarctica. Keys to Antarctica’s geologic past do peek from the ice and lay buried below – but regarding social media claims, what does the scientific evidence show? Pyramid-shaped landform in Antarctica is called a ‘horn’ and is formed through glacial erosion; similar peaks are found around the world A pyramid-shaped mountain (Figure 1) in Antarctica has sparked speculation among social media users who are sharing claims that it is not natural, but rather a pyramid built by an ancient civilization. Although the mountain does have some visual similarities to a pyramid – e.g., having a peak and four sides – there are several clues and lines of evidence indicating that this is a natural mountain peak, as we will detail below. Figure 1 – Unnamed horn located in Antarctica at 79°58’38″S 81°57’44″W (view here). Source: Google Earth screenshot Although this mountain is particularly pyramidal, the shape itself is not rare. Peaks with similar shapes exist around the world and geologists have studied these to understand the natural processes that form them – a field of study called geomorphology. Geologists refer to these types of peaks as ‘horns’ – examples include the famous ‘Matterhorn’ in Switzerland, and the lesser known ‘Alpamayo’ mountain in Peru (Figure 2). Figure 2 – Examples of glacially carved horns: Alpamayo mountain, Peru (left) and the Matterhorn mountain, Switzerland (right). Source: Pexels and Frank R/Wikimedia.org As described in the United States Geological Survey Glossary of Glacier Terminology, horns are “a pointed, mountain peak, typically pyramidal in shape, bounded by the walls of three or more cirques . . . when a peak has four symmetrical faces, it is called a Matterhorn”. Cirques are hollow areas carved into mountains as glaciers move downward and erode (i.e., remove) underlying rock[1]. The intersection of multiple cirques leaves behind a peak (i.e., horn) connected to 3 or 4 ridges – marking the outer boundaries of where the glaciers eroded, as shown in Figure 3 below. Figure 3 – Diagram showing horns, their ridges (i.e., arete), and cirques (i.e., hollowed out areas carved by glaciers). Vertical lines along the faces of the horns represent steep areas resulting from glacial erosion. Source: Illustrated Glossary of Alpine Glacial Landforms: Karen A. Lemke, University of Wisconsin-Stevens Point There is clear evidence of past glacial erosion in this region of Antarctica[2]; however, in some areas, snow and ice cover many of the lower landscape features that make this more apparent. Note that the examples in Figure 2, which are not covered by ice sheets, show less of a pyramidal shape near the base of these mountains. However, the pyramidal peak (Figure 1) shown in social media videos is largely covered in snow and ice, covering many of the landscape features near its base that would likely make it easier to identify as a glacial horn. For this reason, sometimes other observations and information must be gathered from the surroundings to characterize geologic features. This is something that we discussed in a similar past Science Feedback review, linked here. So what do the surroundings tell us? The horn-formation process we described above occurs in cold, glaciated environments, such that of the Ellsworth Mountains of Antarctica where the pyramidal horn is located. Thus, its location matches the environment where this type of peak forms. In fact, this process of glacial erosion is common in Antarctica as evidenced by the number of horns and pyramidal peaks nearby (Figures 4-6). Many pyramidal peaks are documented in a report titled “Geographic Names of the Antarctic” including Abbott Peak, Achilles Mountain, and several others. Figure 4 – A semi-pyramid shaped mountain peak located 9.5 kilometers east-southeast of the mountain shown in Figure 1. Note that with increased snow coverage, this mountain could also appear somewhat pyramid-shaped given the four evenly spaced ridges meeting at a point. Source: Google Earth screenshot Figure 5 – Another pyramidal mountain peak located roughly 230 kilometers north-northwest of the mountain shown in Figure 1. Note that it has a similar pyramid shape, but the snow cover and surrounding ridges in this area makes it clear that this is a mountain that is connected to other peaks and ridges (i.e., not an isolated feature). Source: Google Earth screenshot Figure 6 – Photo of a pyramidal peak near the Princess Elisabeth Station (polar research station). Note the concave eroded faces of the horn, curved ridges, and uniformity of the rock (i.e., no cut blocks, as seen in pyramids), showing evidence of its natural origin and glacial erosion features labeled in Figure 3. Source: International Polar Foundation – René Robert Overall, the peak’s physical characteristics, surrounding glacial environment, and proximity to a number of other pyramidal peaks with similar patterns of glacial erosion, is strong evidence that the pyramidal feature shown in viral social media videos is a natural mountain peak – called a pyramidal peak or horn – formed over time through glacial erosion. Additionally, there is no record of an ancient civilization or any constructed pyramids in Antarctica, which has been surveyed since the early 1900s. Antarctica slowly moved to its current position over millions of years; no evidence of rapid shift A number of viral clips on social media feature Billy Carson speculating about Antarctica’s past. In these videos, Carson claims that ‘Antarctica quickly shifted into its current position on Earth through tectonics and sudden crustal pole shift’. Carson suggests that these two concepts somehow work together; however, they are actually incompatible and only one of them – plate tectonics – is supported by scientific evidence and widely accepted by geology experts[3], as detailed below. As described in Palin and Santosh (2021), “the theory of plate tectonics is widely accepted by scientists and provides a robust framework with which to describe and predict the behavior of Earth’s rigid outer shell – the lithosphere – in space and time”[3]. This well-accepted theory explains that Earth’s outer shell is broken up into different tectonic plates, like a giant jigsaw puzzle (Figure 7), which move around very slowly – i.e., a few centimeters per year[4], or as the USGS explains, roughly at the same rate that your fingernails grow. Figure 7 – Earth’s tectonics plates and continents that overlie them. Source: United States Geological Survey (USGS) Over millions of years, they can carry their overlying continents to different positions on Earth’s surface, and thus sometimes to different climates. Together, these concepts describe the widely accepted theories of plate tectonics and continental drift. In conjunction with past climate variations, these concepts help explain why icy regions (e.g., Antarctica) show geologic evidence of different conditions in their past (e.g., being in warmer climates). Contrary to the universally accepted theories above, some have speculated a ‘cataclysmic pole shift’, caused these climate changes due to rapid shifts in Earth’s crust and poles. However, this does not match the scientific evidence. For example, researchers have studied past shifts in Earth’s poles spanning 160 million years and they explain that the evidence does not support the ‘rapid’ or ‘massive’ polar shift being claimed[5]. Scientific evidence also does not support a rapid shift in Antarctica’s position – a claim suggested in social media videos. Instead, evidence shows that Antarctica began slowly moving to its current position roughly 182 million years ago[6,7]. At that time it was part of a larger supercontinent called Gondwana (Figure 8) – which also included land that we now call South America, Africa, Madagascar, India, Western Australia, and Arabia[7]. To emphasize how slow this transition was, it’s worth noting that East Antarctica and Australia only split from each other around 85 million years ago[7] – 97 million years after Antarctica began separating from Gondwana. Figure 8 – Evolution of Earth’s continents from 250 million years ago to present day. Note that Antarctica was closer to the equator prior to the breakup of Gondwana (or ‘Gondwanaland’) roughly 182 million years ago[6,7], after which it slowly drifted to the south pole over millions of years. Source: USGS Conclusion: There is no evidence of an ancient civilization, nor any pyramids in Antarctica, contrary to claims from viral videos on social media. There are, however, several pyramid or semi-pyramid shaped mountains called ‘horns’ or ‘pyramidal peaks’, which form through glacial erosion. These peaks are well-documented in Antarctica and many other glaciated areas around the world, such as Switzerland and Peru. Contrary to other claims made in these videos, Antarctica did not experience a sudden change in climate due to a sudden shift in the poles or Antarctica’s position on Earth. Scientific evidence shows that Antarctica slowly drifted to its current position over millions of years through tectonic plate movement."
https://science.feedback.org/review/sea-levels-have-risen-for-over-100-years-despite-misleading-photos-social-media/,Inaccurate,"Facebook, 2024-06-06","Sea-level rise is not occurring or showing any impacts, based on photographic evidence.",,"Inaccurate: Scientific evidence unambiguously shows rising sea levels based on measurements of global mean sea level and tidal gauge data, even the ones collected near the locations from social media posts claiming that ‘sea level is not rising’. Misleading: It is misleading to show ‘before and after’ photos from select locations without proper context (e.g., tidal conditions) or an appropriate scale (i.e., one in which the sea level rise that has been reported at these locations could be reasonably seen). ","Scientists have shown that global mean sea level has risen since the year 1880 by analyzing sea-level data from tidal gauges and satellites. Relative sea level rise – which is measured at a local or regional scale – can vary due to Earth’s shape and ocean dynamics. However, the data collected from the locations shown in ‘before and after’ posts on social media also show evidence of sea level rise. Certain locations around the world are more strongly impacted by the effects of rising sea levels. ","There is no evidence of sea-level rise in before and after photos (i.e., from the past and present) from some locations. Therefore, sea-level rise is not occurring or causing negative impacts. ","1 – Church et al. (2011) Sea-level rise from the late 19th to the early 21st Century. Surveys in Geophysics. 2 – Rovere et al. (2016) Eustatic and Relative Sea Level Changes. Current Climate Change Reports. 3 – Slangen et al. (2016) Anthropogenic forcing dominates global mean sea-level rise since 1970. Nature Climate Change. 4 – Horton et al. (2018) Mapping Sea-Level Change in Time, Space, and Probability. Annual Review: of Environment and Resources. 5 – IPCC (2019) Special Report on the Ocean and Cryosphere in a Changing Climate.","Several social media posts have gone viral after sharing ‘before and after’ photos from the past and present to claim that sea-level rise has not occurred. For example, a number of these posts show photos of Sugarloaf Mountain in Brazil, labeled with the years 1880, 1910, and 2020 and captions claiming that sea level is not rising. One such post on Facebook, linked here, has been shared thousands of times. Below we will investigate these claims using scientific evidence, and explore how scientists measure sea-level rise. Scientists determine sea-level rise by collecting and analyzing data, not by comparing a few photos Before investigating the evidence, we will first explain why these viral posts are highly flawed in their ‘method’ of assessing sea-level rise. These posts claim that sea level has not risen based on photos taken at certain locations in different years; examples of which are shown in Figure 1. Figure 1 – Examples of locations shown in social media posts claiming that ‘sea levels have not risen’. The two top left photos are of Fort Denison in Sydney Harbour; the two bottom left photos are of the Statue of Liberty in New York City; and the two photos on the right half of the figure are of Sugarloaf Mountain in Brazil. Source: social media screen captures However, using these photos for comparison is flawed because they are missing critical details and context. There are a number of variables that affect sea level; one of the most important in this case is tidal conditions. Even if two photos are taken at the exact same location on the same day, the sea level at that location will be different at low and high tide (i.e., at different times of the day). As explained by the National Oceanic and Atmospheric Administration (NOAA), tides are changes in sea level that are caused by the gravitational pull on our oceans by the Earth, Moon, and Sun. These forces cause the oceans to bulge outward, roughly in line with the moon, and dip inward at a right angle to this line (Figure 2). Figure 2 – Diagram showing tidal bulge as a result of net gravitational pull on Earth’s oceans. Note that these bulges are exaggerated for visualization purposes, and that as a coastline passes through a bulge, its respective landmass (e.g., continent) has a much higher elevation than the rise in sea-level – and thus does not become fully submerged by the rising oceans. But instead, it experiences a high tide. Adapted from the following source: NASA/Vi Nguyen Because Earth rotates over a 24 hour period, sea-levels change throughout the day as both landmasses and oceans collectively move through these bulge and dip zones. This causes alternating high and low tides every 6 hours. The difference in sea level at low and high tide depends on the position of the Moon. For example, NOAA explains that “the greatest difference in height occurs around new and full moons, 6.27 ft. (1.91 m) and 7.18 ft. (2.19 m) respectively”. An example of sea-level fluctuations over days to weeks with different tides is shown in Figure 3 below. For a more in-depth explanation and visualization of how tides work, see the link here. Figure 3 – Sea-level fluctuations in Santa Barbara, California, over days to weeks. Days are shown on the x-axis and average/mean sea-level height (MSL) in feet is shown on the y-axis. The moon phases are shown above the graph, with the corresponding differences in high and low tide elevations shown directly below them. Note that the largest differences occur during a new moon and a full moon. Source: NOAA Because of the processes described above, it is flawed to compare sea level in two different photos without knowing the date and time, and thus the tidal conditions when they were taken. Hypothetically, an older photo could be taken at a high tide and a newer photo taken at a low tide, disguising the sea-level change occurring between those years. However, even with more context for the photos, there is still another major flaw with this method; they collected no actual measurements, and there is no appropriate scale in the photos. For example, in one of the claim-making posts they show photos of the ocean below a landmark called Sugarloaf Mountain, with a peak of 396 meters (1,299 feet) located in Rio de Janeiro. However, there is no scientific consensus that this landmark, or the others shown in these posts, should show visual changes due to sea level rise that occurred between the photo dates. Over the alleged time period shown in the photos of 1880-2020, global mean sea level (GMSL) has risen roughly 21–24 centimeters (8-9 inches), according to NOAA (Figure 4). However, based on Google Earth measurements, the photo was taken at a distance that shows nearly a 2 kilometer stretch of land – a scale that does not match the magnitude of sea-level rise in this period. Figure 4 – Global average absolute sea-level change (in inches) from 1880-2021, based on tidal gauge measurements (orange line) and recent satellite measurements (blue line). Note that ‘absolute’ sea-level change is used to represent the ocean’s surface, without regard to changes in nearby land elevation. Figure source: United States Environmental Protection Agency (EPA) with data from NOAA and CSIRO (2017)[1] It is also misleading to cherry pick a few locations (e.g., near Sugarloaf Mountain) to show the ‘impacts’ of sea-level rise, because sea-level rise and its effects vary by region. This is part of the reason scientists create flood vulnerability and exposure maps, like the one linked here. One reason for this variability is that steep areas are less susceptible to inundation (i.e., flooding from rising water) than low-lying areas. This occurs because water needs to rise higher to submerge high-elevation areas than does for areas of lower elevation. This is apparent on flatter beaches, for example, because at high tide the ocean moves much further inland than it does on steeper beaches. When scientists study sea-level rise, they do not rely on ‘before and after’ photographs from one location. Instead, they collect data from around the world and use it to observe trends. In doing so, they can measure sea-level rise more accurately, and avoid the uncertainty that comes with comparing photographs without adequate information and scale. So what does the evidence show when scientists properly collect and analyze sea-level data? Data from around the world shows that global mean sea-level has risen over the last century; some areas have risen more than others The social media posts actually make two claims – the explicit claim that sea level is not rising and the implied claim that it is not problematic, otherwise we should see visual evidence of impacts in photos of these locations. The reason these types of posts can convince viewers is that they simplify a complex topic. The underlying assumption in these posts, for example, is that ‘if sea level has risen, these locations – and by extension, all coastal areas – on Earth should show evidence of it in before and after photographs’. However, this disregards an important scientific observation: sea level does not rise at the same rate everywhere on Earth[2] – it is uneven and varies by location, as we will explain below. To evaluate how sea levels change over time, scientists evaluate trends in data from tide gauges and satellites. As shown in Figure 4 from the previous section, these data clearly show that global mean sea level has risen since 1880 – the earliest alleged date of the photos recently shared in these posts. If global mean sea level (i.e., overall sea level) has risen, and sea level does not rise at the same rate everywhere on Earth – what happens at a local or regional level? What changes should we see? That depends on the location. At a local level, some places are more vulnerable to the effects of sea-level rise than others. As we briefly explained earlier, one reason for this is that the terrain (e.g., flatness or steepness) of different areas can affect how ocean water moves inland during tidal changes. For this reason, a photo taken at low tide might show land exposed that would later be submerged in a photo taken at high tide. An example of this is shown in Figure 5 below. Note the difference in land exposure between the photos, which could be misleading without context about the tidal conditions when they were captured. Figure 5 – Photographs taken at high tide (left) and low tide (right) at the Bay of Fundy in Canada. Note that the land exposure changes between high tide and low tide. Source: NOAA SciJinks At a broader/regional scale, there are other physical processes that affect sea-level rise. As we mentioned, sea-level rise is not even – it does not rise in the intuitive way that water does in something like a bathtub. This is because at a planetary scale, there are many other factors at play. As explained by NASA, “The globally averaged trend toward rising sea levels masks deeper complexities. Regional effects cause sea levels to increase on some parts of the planet, decrease on others, and even to remain relatively flat in a few places.” They explain that two of the factors influencing uneven sea-level rise at a regional level are ocean dynamics (i.e., redistribution of water mass by currents, wind, etc.) and varying gravitational strength. They explain that “because the distribution of Earth’s mass is uneven, Earth’s gravity is also uneven. Therefore, the ocean’s surface isn’t actually a perfect sphere or ellipsoid; it is a bumpy surface” (Figure 6). Figure 6 – Visualization of Earth’s gravitational field showing regions with red showing areas where gravity is stronger, blue where gravity is weaker, and a spectrum between. Source: NASA with data from University of Texas Center for Space ResearchDespite local and regional variability, several individual locations – such as those shown in the social media post photos – do in fact show sea-level rise based on tidal gauge data. For example, one of the locations discussed earlier – Sugarloaf Mountain (Figure 1) – that was shared in the posts has nearby sea-level measurements from 1963-2016, which show that sea level rose 12.6 centimeters (4.5 inches) in that period. Another location shown in these posts is Sydney Harbour (Figure 1). Science Feedback has already addressed claims regarding sea-level rise at this location in a previous review, linked here. The results of that review are well-summarized in a quote provided to Science Feedback by Dr. Thomas Frederikse, Postdoctoral researcher at the Jet Propulsion Laboratory/California Institute of Technology: “At Fort Denison, which is the building in the picture [Figure 1], we have two long tide gauge records. One that covered 1886-1993, and one that started in 1915 and is still measuring today. I’ve plotted both individual records and the average of them. Both the records clearly show that sea level is rising in Sydney, and that the rate of the rise is increasing.” A third location from these social media posts is the Statue of Liberty in New York City (Figure 1). As with the other examples, this location also shows a clear rise in sea level; from 1856-2023 the sea level in this area rose by roughly 49.1 centimeters (19.33 inches) (Figure 7). Figure 7 – Relative sea level trend based on data from 1856-2023 at The Battery in New York (close to the Statue of Liberty). Source: NOAA In summary, all three locations above – which are commonly used in social media posts to claim sea levels have not risen – show clear evidence of sea-level rise. In addition, previous Science Feedback reviews have also found evidence that global mean sea level rise is speeding up. As explained in a review from 2021 linked here: while land mass movements and ocean circulation patterns influence sea levels, human-induced climate change is accelerating the rate of sea level rise[3]. This point is also summarized in a 2018 paper by Horton et al.: “a large portion of the twentieth-century rise, including most GMSL rise over the past quarter of the twentieth century, is tied to anthropogenic warming”[4]. The Intergovernmental Panel on Climate Change (IPCC) – the world’s leading authority on climate science – explains that “as a consequence of natural and anthropogenic changes in the climate system, sea level changes are occurring on temporal and spatial scales that threaten coastal communities, cities, and low-lying islands”[5].They also explain that “coastal ecosystems are already impacted by the combination of SLR [sea-level rise], other climate-related ocean changes, and adverse effects from human activities on ocean and land”[5]. Conclusion: Scientists have shown that global mean sea level has risen since the year 1880 by analyzing data from tidal gauges and satellites. Relative sea level rise – that which is measured at a local or regional scale – can vary due to Earth’s shape and ocean dynamics. However, contrary to claims from social media users, even the locations from photos on their posts show rising sea levels based on tidal gauge measurements. Social media posts comparing ‘before and after’ photos of cherry-picked locations to ‘assess’ sea-level rise are flawed because they are missing important details about tidal conditions, scale, and context about how sea levels are measured and vary across Earth. Additionally, implying that there are no impacts is inaccurate because evidence shows that rising sea levels have already caused negative impacts (e.g., to coastal ecosystems)."
https://science.feedback.org/review/colorful-auroras-seen-may-2024-caused-by-mass-ejections-from-sun-not-haarp-experiments/,Incorrect,"Facebook, YouTube, TikTok, X/Twitter, 2024-05-11",May 2024 auroras were caused by experiments from High-frequency Active Auroral Research Program (HAARP) experiments,,The origin of auroras in Earth’s atmosphere is well-studied and occur as solar winds and ejections of magnetized plasma from the Sun approach Earth and interact with our planet’s magnetic field. HAARP is incapable of producing the auroras that were observed because their power output is orders of magnitude less than would be necessary to do so. ,"The High-frequency Active Auroral Research Program (HAARP) is a research facility that uses a high-power, high-frequency transmitter to study the physical properties and behavior of the highest point of the atmosphere, the ionosphere. Radio transmissions from HAARP only cause small effects in the ionosphere that last for a brief span of a few seconds. HAARP is incapable of causing the magnitude of aurora effects witnessed in May 2024; evidence shows these effects were caused by mass ejections of magnetized plasma from the Sun. ","The vivid lights seen around the world on May 10 2024 were artificial aurora effects caused by High-frequency Active Auroral Research Program (HAARP) experiments, not by a geomagnetic storm.","1 – McCoy et al. (2018) Haarp, a Powerful Active Ionospheric Laboratory Open for International Research. 42nd COSPAR Scientific Assembly. 14-22 July 2018, Pasadena, California, USA 2 – Todd Pedersen (2015) HAARP, the most powerful ionosphere heater on Earth. Physics Today. 3– Inan et al. (2004) Multi‐hop whistler‐mode ELF/VLF signals and triggered emissions excited by the HAARP HF heater. Geophysical Research Letters. 4 – Piddyachiy et al. (2011) DEMETER observations of the ionospheric trough over HAARP in relation to HF heating experiments. Journal of Geophysical Research: Space Physics.","On 10 May 2024, solar eruptions caused a several-day geomagnetic storm on Earth, causing a vivid display of colors, called auroras, which were witnessed in skies around the globe. This natural event coincided with experiments by the High-frequency Active Auroral Research Program (HAARP), which triggered dozens of social media users to claim that these experiments were responsible for the widely-seen aurora effects. As of the publication date for this article, one YouTube video gathered over 270K views after discussing some of the claims people are making about HAARP’s connection to the recent auroras. We will investigate the main claims below and explore the scientific evidence for the cause of the recent auroras. Colorful auroras appeared across the globe in May 2024 due to asolar storm that scientists warned about Although the recent auroras were exceptionally wide-spread and a surprise to most who saw them, their presence was not a mystery to scientists. Scientists have long known that certain types of solar activity lead to aurora effects in Earth’s atmosphere. The most well-known example of this phenomenon is the aurora borealis (i.e., the northern lights), which have been documented for centuries – long before the establishment of HAARP in 1990. Auroras are caused by the interactions between solar winds and Earth’s magnetic field (i.e., magnetosphere) which protects our planet, as shown in Figure 1 below. These solar winds contain a plasma of electrically charged particles which interact with Earth’s magnetic field, accelerating electrons along its magnetic field lines (blue lines in Figure 1) which then bombard and energize molecules in Earth’s atmosphere causing them to glow and form auroras. Figure 1 – Simplified illustration (not to scale) showing solar wind (orange arrows) interacting with Earth’s magnetic field (blue) which causes the aurora borealis in a region called the ‘auroral oval (green). Source: Tromsø Geophysical Observatory (TGO) The northern lights are a more regular occurrence in the auroral oval due to the interactions described above and geometry shown in Figure 2 below; however, the Sun occasionally has increased activity (e.g., solar storms) which leads to greater visibility of auroras from other places on Earth, as witnessed on 10-11 May 2024. Figure 2 – Location of the auroral oval (green) where the northern lights are commonly seen. This region can vary with changes in solar winds, which accelerate electrons along the magnetic field lines (thin lines shown above) and down to Earth’s atmosphere where they excite molecules which glow and form auroras. Source: NOAA On 9 May 2024, the National Oceanic And Atmospheric Administration (NOAA) issued a Severe (G4) Geomagnetic Storm Watch due to a series of solar flares and coronal mass ejections (CMEs) that began the day prior. One of the solar flares from sunspot ‘AR3664’ was observed by NOAA’s GOES-16 satellite on 9 May 2024, as shown around the four second mark in the video linked here, and shown in the ‘after’ photo of Figure 3 below as a bright flash of light on the lower right. Figure 3 – Solar flare from sunspot ‘AR3664’ observed by NOAA’s GOES-16 satellite on 9 May 2024. Images screen-captured from NOAA’s GOES-16 video footage, with the before photo (left) captured seconds before the after photo (right). Source: NOAA’s Space Weather Prediction Center (SWPC) NOAA later shared an X/Twitter post explaining that the geomagnetic storms reached level G5 – the highest in the scale from 1-5 – which last occurred in 2003. This solar storm originated from a cluster of sunspots that is roughly 17 times the diameter of Earth, which spewed magnetized plasma that hurtled towards Earth at ~1,800 kilometers/second. Once reaching Earth’s magnetic field, this resulted in an aurora that could be seen from areas on Earth where it is normally not possible. Based on this evidence, we can confidently conclude that a solar storm was responsible for the auroras witnessed around the world on 10-11 May 2024. However, as we noted earlier, dozens of social media posts claimed that HAARP experiments were the cause of these auroras. Examples of these posts can be found in the following links: X/Twitter post, TikTok video 1, TikTok video 2, Facebook post. Below we will explore what HAARP is and the experiments they were conducting. No evidence that the HAARP experiments were related to the auroras observed in May 2024 A press release from HAARP was posted on 13 May 2024, explaining that “the HAARP scientific experiments were in no way linked to the solar storm or high auroral activity seen around the globe”. But what is HAARP and what experiments did they recently conduct? HAARP is a research facility operated by the University of Alaska Fairbanks[1]. It transmits high-frequency radio signals into the highest point of the atmosphere, the ionosphere, using 360 radio transmitters and 180 antennas. The facility covers about 14 hectares (0.14 kilometers squared) near the town of Gakona, Alaska, which is about 250 kilometers northeast of Anchorage, Alaska’s largest city. The radio signals are partially absorbed between 100 kilometers and 350 kilometers in altitude, accelerating electrons in the ionosphere and briefly “heating” it up[2]. By analyzing how radio waves interact with electrons in the ionosphere[3,4], researchers at HAARP are able to study phenomena, such as the effects of the aurora borealis (i.e., northern lights) on radio systems and aircraft communications at high altitudes. The experiments that HAARP conducted between 8-10 May 2024 “supported research proposals from the University of Alaska Fairbanks to study mechanisms for the detection of orbiting space debris”. They explain that these experiments were conducted to help improve collision detection for satellites, and were scheduled roughly a month and a half ahead of the geomagnetic storm. As they HAARP explains in their press release, “the timing was purely coincidental; geomagnetic storms are unpredictable, with lead times before a solar event is detected from Earth measured in minutes, not months”. Beyond the fact that the HAARP experiments were unrelated to the observed auroras in May 2024, the HAARP instruments are also incapable of producing those effects. The maximum radiative power of HAARP’s antennas is 3.6 megawatts[2], whereas a strong geomagnetic storm – such as that observed on 10-11 May 2024 – inputs upwards of 100 gigawatts of power into Earth’s magnetosphere and ionosphere (i.e., the study area of HAARP experiments). This means that the power received from the geomagnetic storm was 10,000 times greater than HAARP’s maximum power output. In a similar explanation from HAARP, they note: “interestingly, coronal mass ejections, like the one associated with the recent geomagnetic storm, typically release more than 10^24 Joules of energy. By comparison, the high- frequency (HF) transmitter at HAARP is only a ~3 megawatt (MW) transmitter; it would take HAARP over 10 billion years to produce enough energy to affect this naturally occurring phenomenon”. Science Feedback has covered the limitations of HAARP’s capabilities in previous claim reviews – an example is linked here. Conclusion: In summary, there is conclusive evidence that the aurora observed around the globe on 10-11 May 2024 was caused by a solar storm that began erupting from the Sun on 8 May 2024. The claims attributing the auroras to HAARP experiments that coincided with this event are simply incorrect. As explained above, not only is HAARP incapable of producing the observed auroras from its limited power output, but the experiments – which were scheduled over a month in advance – were conducted to study space debris, unrelated to auroral effects."
https://science.feedback.org/review/no-evidence-significant-influence-volcanoes-solar-variability-on-recent-climate-change-contrary-judith-curry-claims-prageru-video/,Misleading,"PragerU, Judith Curry, 2024-04-15",Climate scientists disagree about how much warming is associated with our emissions and whether this warming is larger than natural climate variability from the sun and volcanic eruptions,,"Misleading: Climate scientists have studied natural climate variability and the contribution of human CO2 emissions to recent climate changes. The resulting evidence unequivocally shows that anthropogenic CO2 emissions are the most significant driver of recent climate change, while natural variability has made a minimal contribution.  Unsupported: There is no evidence to support that solar variability or volcanic activity have had a significant impact on recently rising global temperatures at multidecadal to century timescales. In fact, solar intensity is currently declining while global temperatures are rising. ",Scientific evidence shows that modern global warming is primarily driven by increasing CO2 emissions from human activities. There is no evidence that solar variations or volcanic activity are substantial drivers of recent climate change. ,"Climate scientists disagree about how much warming is associated with our emissions and whether this warming is larger than natural climate variability; “Variations in the sun and volcanic eruptions also have a substantial impact [on Earth’s climate], but these are simply unpredictable”.","1 – IPCC (2021). Sixth Assessment Report. 2 – Zhong and Haigh (2013) The greenhouse effect and carbon dioxide. Royal Meteorological Society Weather. 3 – PAGES 2K Consortium (2019) Consistent multidecadal variability in global temperature reconstructions and simulations over the Common Era. Nature Geoscience. 4 – Le Quéré et al. (2016) Global Carbon Budget 2016. Earth System Science Data. 5 – Knapp et al. (2010) The International Best Track Archive for Climate Stewardship (IBTrACS): Unifying tropical cyclone best track data. Bulletin of the American Meteorological Society. 6 – Lean et al. (2020) Solar irradiance variability: Modeling the measurements. Earth and Space Science. 7 – Gerlach (2011) Volcanic Versus Anthropogenic Carbon Dioxide. American Geophysical Union EOS. 8 – Sully et al. (2019) A global analysis of coral bleaching over the past two decades. Nature. 9 – Vicedo-Cabrera et al. (2021) The burden of heat-related mortality attributable to recent human-induced climate change. Nature. 10 – Lüthi et al. (2023) Rapid increase in the risk of heat-related mortality. Nature. 11 – Ballester et al. (2023) Heat-related mortality in Europe during the summer of 2022. Nature. 12 – Hausfather et al (2019) Evaluating the Performance of Past Climate Model Projections. Geophysical Research Letters. 13 – Robock (2000). Volcanic eruptions and climate. Reviews of Geophysics. Note: Scientists comments were lightly edited for clarity (i.e., information was added in brackets for context and minor punctuation changes were made).","On 15 April 2024, PragerU posted a short video on their website and YouTube titled “The Good News about Climate Change”, which gathered over 500,000 views combined as of the publication date of this review. The video features a former professor, Dr. Judith Curry, who makes claims about the current state of climate change knowledge – the knowns and unknowns, agreements and disagreements. Below we will share our investigation of some of these claims using scientific evidence, followed by evaluations of these claims from scientists with relevant expertise. Recent rises in global temperatures are being driven by CO2 emissions from human activity; evidence shows that natural variability cannot account for these changes In the video, Curry attempts to summarize what climate scientists agree and disagree about on climate change. She claims that they agree on the following: “the average global surface temperature has increased over the last 150 years; humans are adding carbon dioxide to the atmosphere by burning fossil fuels; and, carbon dioxide emissions have a warming effect on the planet.” The claims above do in fact represent some, but not all, of the findings shared by the Intergovernmental Panel on Climate Change (IPCC), the world’s leading authority on climate science. This is an important distinction because it is misleading to imply that these are the only three things that climate scientists agree on – or, more accurately, that the scientific evidence unequivocally shows. For instance the IPCC also reports that “rising greenhouse gas concentrations are driving profound changes to the Earth system, including global warming, sea level rise, increases in climate and weather extremes, ocean acidification, and ecological shifts.”[1] It is well established among scientists that humans are adding carbon dioxide (CO2) to the atmosphere by burning fuels, and that CO2 has a warming effect on the planet through the greenhouse effect. While remaining in the atmosphere, CO2 prevents heat from escaping and consequently warms the surface of Earth – a concept that is popularly known as the greenhouse effect. This is a consequence of the properties of CO2, which allow sunlight to pass through to Earth’s surface, but cause CO2 to absorb and re-emit the energy that returns (i.e., infrared radiation emitted from Earth’s surface after absorbing sunlight)[2] . It is also well established that global mean surface temperature (GMST) has been rising for over 150 years, as shown in Figure 1 below. In the most recent year, 2023, the National Oceanic and Atmospheric Association (NOAA) reported that “The average global land and ocean surface temperature for January–December 2023 was 1.18°C (2.12°F) above the 20th century average of 13.9°C (57.0°F)—the highest global land and ocean temperature for January–December in the 1850–2023 record.” Figure 1 – Observed global mean surface temperatures from 1850 to 2020 using four data sets. The horizontal lines represent different time ranges and are annotated to show the rise in GMST in the respective time periods. Source: IPCC (2021)[1] Although Curry’s claims above about agreement amongst climate scientists are scientifically supported, that ceased to be the case in her following claim that climate scientists disagree about “how much warming is associated with our emissions” and “whether this warming is larger than natural climate variability”. “This is absolutely not true”, explained Dr. Ella Gilbert, Regional Climate Modeller at the British Antarctic Survey, “we know unequivocally that human activity is responsible for the vast majority of observed warming, and that natural factors make up a very small proportion of the changes seen in the last few centuries.” Climate scientists know this because they have investigated the impact of natural inputs (e.g., solar, volcanic, etc.) and human CO2 emissions on global temperatures, and have also compared modern temperature trends to natural variations. This allows scientists to determine the relative contributions of these inputs to global warming and determine how modern global warming compares to natural variability. As shown below in Figure 2, greenhouse gases overall cause the most global warming of all the climate change drivers, and CO2 causes the most global warming of all the greenhouse gases. Figure 2 – The contributions of different drivers to global warming from the present time period (2010-2019) relative to the time period of 1850-1900. The estimates of warming (red) and cooling (blue) from radiative forcing studies (panel (c)) are based on both direct emissions into the atmosphere and their effect, if any, on other climate drivers. Source: IPCC (2021)[1] Scientists have also investigated which physical properties control the climate system and have quantified their influence on global temperatures. By incorporating all these physical properties in global climate models, they have been able to simulate the climate from 1850 to present day. As shown in Figure 3 below, the simulation that only included natural variables (solar and volcanic) was unable to match observed global temperature changes over the period of 1850-2020. However, the addition of human drivers – such as CO2 emissions – lead to a much closer match between simulated and observed temperatures. These simulations also show that human greenhouse gas emissions are the only variable that can reproduce observed temperatures; other natural phenomena (i.e., solar and volcanic influences) fail to explain the recent rise in global temperatures. Figure 3 – Observed and simulated changes in global surface temperature from 1850 to 2020. The black line represents 170 years of observed data and is compared to Coupled Model Intercomparison Project Phase 6 (CMIP6) climate model simulations. The brown area represents the temperature response to both human and natural drivers and the green area to only natural drivers (solar and volcanic activity). Solid colored lines represent the averages, and the shaded areas represent the very likely range for the models. Source: IPCC (2021)[1] The figures above help explain how human inputs, such as greenhouse gas emissions, have driven recent global temperature changes. However, scientists have also compared these changes to natural variations over longer time periods. After analyzing data from the past 2000 years, studies have shown evidence that modern global warming trends are unusual compared to past variations over this period. For example, PAGES 2K Consortium (2019), explains that over the last 2000 years “the largest warming trends at timescales of 20 years and longer occur during the second half of the twentieth century, highlighting the unusual character of the warming in recent decades.”[3]As shown in Figure 4 below, the black line – representing modern instrumental temperature records – shows that recent temperatures have exceeded the upper range of natural (pre-industrial) warming rates of the last 2000 years. Figure 4 – 2000 years of global warming/cooling rates averaged across 51 years and based on paleoclimate records. Modern instrumental temperature records shown in black. Data sourced from Neukom et al. (2019) and PAGES 2k Consortium (2019). Source: University of Bern Note that the warming/cooling rates above are averaged across 51 years; evaluating trends at these timescales (20 years and longer) is important because, as the IPCC explains, “over periods of a couple of decades or less, natural climate variability can dominate the human induced surface warming trend.”[1] That is to say that natural variability has less of an effect at timescales of decades to centuries. So looking at longer time periods allows scientists to better understand how human activities are impacting warming trends, without the ‘noisy’ ups and downs in temperature data observed at shorter timescales. As explained by the IPCC, “over the entire historical period (1850–2019), natural variability is estimated to have caused between -0.23°C and +0.23°C of the observed surface warming of about 1.1°C. This means that either the majority, or all, of the warming has been driven by human activities, particularly emissions of greenhouse gases”[1]. To conclude, Curry’s claim is at odds with the science on this point. Scientific knowledge has demonstrated that the vast majority of the observed warming can only be explained by the forcing created by greenhouse gases added to the atmosphere by human activities. Regarding scientific agreement among climate scientists, Dr. Kerry Emanuel, Professor Emeritus of Atmospheric Science at the Massachusetts Institute of Technology, explained: “There is a widespread scientific consensus that a strong signal of global mean temperature increase has emerged from natural background variability and that it is not caused by other kinds of radiative forcing changes, such as solar output. Of course, as in all scientific endeavors, there is a minority dissent, but in this case that has been reduced to typical background noise levels.” Evidence shows that recent climate change is not being driven by solar variability or volcanoes Over the years, claims continue to pop up regarding the impacts of solar activity and volcanoes on climate change. Science Feedback has addressed many of these in several past reviews, and in each case – now including this film – the claims were inconsistent with available evidence. See examples of these claims in the past reviews linked below: Review: 1: The sun isn’t responsible for current climate change, contrary to claims in Suspicious0bservers YouTube video Review 2: Low solar activity has little effect on Earth’s climate, contrary to claim in The Sun Review 3: Claim that current climate change can be explained satisfactorily by natural cycles and volcanic activity does not have scientific support Review 4: Evidence greenhouse gasses cause global warming denied by Willie Soon in Tucker Carlson interview, resulting in mass social media climate misinformation Curry claims that “Variations in the sun and volcanic eruptions also have a substantial impact [on Earth’s climate], but these are simply unpredictable”. Although this matter has been partially addressed above by comparing natural and human climate drivers, we will further investigate below. To gain expert insight on this matter, we interviewed Dr. Ian Richardson, Principal Research Scientist at the University of Maryland, who studies the interplanetary environment between the Sun and the Earth. After reviewing Curry’s claim, Dr. Richardson commented: “The solar influence on climate appears to be small. Changes in the solar visible and infrared irradiance are only ~0.1%, so the effect is not ‘substantial’ and tracks the 11-year solar cycle, so in this sense the changes are not ‘unpredictable’.” Dr. Richardson’s comment above aligns with evidence found in past Science Feedback reviews on this subject. For example, one of the Science Feedback reviews linked above explains that the rate and magnitude of modern global warming is too high to be caused by solar variability. As shown in Figure 5 below, solar irradiance and global temperatures show opposing trends; solar irradiance has shown no net increase since 1950, but temperatures have continued to rise. If changes in solar activity were a primary driver of recent climate change, we would expect to see global temperatures decrease with total solar irradiance, but the opposite has occurred in recent times. Figure 5 – Comparison of the global surface temperature changes (red) and the Sun’s energy that Earth receives (yellow) in watts per square meter since 1880. One can see that since the 1960s, the global temperature and solar activity have varied in opposite directions. Source: NASA/JPL-Caltech Regarding volcanic influences on Earth’s climate, the IPCC explains that large volcanic eruptions can actually have a cooling effect, as they release small particles into the upper atmosphere which reflect sunlight[1]. However, these effects are short lived; “Volcanic eruptions can cool the climate by a few tenths of a degree for a couple of years, but this is only a short-term effect compared to the long-term warming by human greenhouse gas emissions”, explained Dr. Georg Feulner, Deputy Head of Research Department at Potsdam Institute For Climate Impact Research. He also commented that Curry’s claim “overemphasizes the role of the sun and volcanic eruptions”. Feulner’s comments can be viewed in more detail near the bottom of this review. As shown earlier in Figures 2 and 3, other drivers – such as CO2 emissions from human activities – have had a far greater impact on Earth’s climate in recent times. Volcanic eruptions can also increase atmospheric CO2; however, as explained by Tobias Fischer, Volcanologist and Professor at The University of New Mexico, “during a typical year, volcanic eruptions contribute only about 0.006% of the global anthropogenic CO2 flux. The average CO2 emission of a person living in the USA is about 16 tons of CO2 per year[4] . Therefore, in any given year volcanic eruptions produce only about as much CO2 as 130,000 Americans, or less than the population of Wyoming—the state with the lowest population in the US.” More on this topic can be found in this linked review. Conclusion: and Final Remarks As we have shown above, the claims that Curry makes about climate change drivers are misleading and unsupported. Although Curry accurately listed some (but not all) of the unequivocal climate science findings (e.g., CO2 warms the planet, burning fossil fuels releases CO2, and global temperatures have been rising for 150 years), it was phrased in a misleading way that suggests that those were the only solid findings. This excludes many unequivocal findings that are outlined in the IPCC Sixth Assessment Report, for example. Additionally, her characterization of the uncertainties (i.e., disagreements among climate scientists) does not align with available scientific evidence. The evidence shows that CO2 emissions from human activities are the primary driver of recent rising global temperatures, and there is no evidence that natural variability can account for these changes. On the contrary, natural climate drivers such as solar variability and volcanic activity, have made a minimal impact compared to CO2 emissions from human activities. The information included thus far has addressed the claims that could be investigated using only scientific evidence, without discussion of policy options – which moves into ‘opinion’ territory. For this reason, we have not discussed the underlying message in the video which suggests that “all things considered, planet Earth is doing fine” and that if we focus only on adapting to effects of climate change, there is reason to be optimistic. However, as explained by Richardson, “choosing between either trying to change climate by moving away from fossil fuels or “adapting” to the effects is a red herring. You can do both.” This is why climate scientists discuss climate hazards in terms of both vulnerability (e.g., lack of proper infrastructure) and exposure (e.g., changing climate conditions). The IPCC explains that “continued GHG [greenhouse gas] emissions will further affect all major climate system components, and many changes will be irreversible on centennial to millennial time scales.”[1] They also explain that the available adaptation options will decrease as global warming increases. This provides further reason to focus on both aspects of risk mitigation – reducing known drivers of climate change and improving infrastructure. Scientists’ Feedback: Kerry Emanuel Professor of Atmospheric Science, MIT:There is a widespread scientific consensus that a strong signal of global mean temperature increase has emerged from natural background variability and that it is not caused by other kinds of radiative forcing changes, such as solar output. Of course, as in all scientific endeavors, there is a minority dissent, but in this case that has been reduced to typical background noise levels. On the more consequential question of whether this has caused increases in certain kinds of natural hazards, such as wildfires and hurricanes, there is no general answer that covers them all and we have to look at each hazard in each region. Since the mid 1990s, North Atlantic tropical cyclone activity, including landfalling storms, have been at levels not seen in records going back to 1900, even though there was some elevation of activity in the 1930s as well as the 1950s and 60s. Only about one third of North Atlantic tropical cyclones affect the continental USA, so we have a problem seeing trends with such small numbers, but the decade of the 2000s far surpassed the 1930s in US landfalling hurricane power [based on IBTrACS data][5]. Ian Richardson Research Scientist, NASA/University of Maryland:[In the video, ] there’s a lot of “cherry-picking” of what are generally facts in themselves that are strung together to try to make the point that we shouldn’t move away from fossil fuels. e.g., the Lake Chad example appears to be an inexpert politician not taking account for what appears to be the actual cause of the lake failing and says nothing about the reality of climate change. The 97% “per capita” decrease in the effect of bad weather is a rather meaningless statistic since there has been a huge increase in the population – and hence also in the number of people that are likely to be impacted by such a weather event. Choosing between either trying to change climate by moving away from fossil fuels or “adapting” to the effects is a red herring. You can do both. And it’s only practical to adapt so far. For instance, you can build sea walls, but not everywhere (and how do you choose where? – that’s an economic/political decision that may not be available to poor low-lying countries) and it’s not feasible to keep adding height as sea levels rise. Similarly for controlling water resources which are finite and subject to the effects of climate change. Any models used in science are imperfect but that doesn’t mean that they can’t provide insight and guidance and should be dismissed. Specifically, they may not include solar and volcanic effects because they are assessed to be unimportant. The solar influence on climate appears to be small. Changes in the solar visible and infrared irradiance are only ~0.1%, so the effect is not “substantial” and tracks the 11-year solar cycle, so in this sense the changes are not “unpredictable”. The irradiance has also declined since around 1980 as a result of the ~100 year Gleissberg cycle, whereas global temperature has risen during this time. Solar activity is somewhat “unpredictable” on short timescales[6] (days/weeks) and there is debate about whether for example variations in solar X-rays, ultraviolet radiation and energetic particles can influence the atmosphere and ionosphere on such timescales, but that’s confusing weather with long-term climate variability. Volcanoes are clearly unpredictable. There’s a useful summary at USGS [US Geological Survey]. The main issues with respect to climate change appear to be emissions of sulfur dioxide, which tends to cause atmospheric cooling, and carbon dioxide, which contributes to heating. However, the CO2 contributed by even large volcanoes is small compared to annual (2010) anthropogenic CO2, which is equivalent to 3500 Mount St. Helen’s or 700 Pinatubo eruptions and that volcanos add less than 1 percent of that produced by human activities[7]. Ella Gilbert Research Scientist, British Antarctic Survey:1. Curry’s claim: Climate scientists disagree about the most consequential issues: how much warming is associated with our emissions, and whether this warming is larger than natural climate variability. This is absolutely not true. We know unequivocally that human activity is responsible for the vast majority of observed warming, and that natural factors make up a very small proportion of the changes seen in the last few centuries. For example, the IPCC’s most recent report (AR6) contains the following in its working group 1 report summary for policymakers (section A1.3): “It is likely that well-mixed GHGs contributed a warming of 1.0°C to 2.0°C, other human drivers (principally aerosols) contributed a cooling of 0.0°C to 0.8°C, natural drivers changed global surface temperature by –0.1°C to +0.1°C, and internal variability changed it by –0.2°C to +0.2°C.”[1] i.e. that the contribution of natural factors to warming is *at very least* ten times smaller than that of greenhouse gases, and possibly very much smaller. The impact of natural drivers may not even be causing warming at all[1]. 2.Curry’s claim: “For the past 50 years, the global climate has been fairly benign. In the US, the worst heat waves, droughts, and hurricane landfalls occurred in the 1930s—much worse than anything we’ve experienced so far in the 21st century.” Climate change has been shown to increase the severity and intensity of extreme events such as wildfires, floods and heatwaves (IPCC, 2021). These kinds of events threaten ecosystems (for instance causing mass coral bleaching events, as have been reported recently[8] – see, e.g. Sully et al. 2019) and carry extreme risk to peoples’ lives (Vicedo-Cabrera, 2021; Lüthi et al., 2023)[9,10] – e.g. 70,000 people died in Europe during the heatwave of 2003 and more than 60,000 died in 2022’s European heatwave (Ballester et al., 2023)[11]. Extremes also threaten livelihoods, especially those based on agriculture and natural resource use. That the impacts of individual extreme events are now generally lower than in the 1930s is due to the fact that we are more prepared and have better tools to adapt and plan for extremes. Besides, people are less vulnerable in other ways (thanks to e.g. better health, fewer labour-intensive outdoor jobs and greater economic support), which means the death toll and losses associated with e.g. droughts, wildfires, heatwaves are lower. 3. Far from being “unreliable” and based on incorrect “assumptions”, models are actually very good at making predictions – Hausfather et al. (2019) shows how well even the oldest, simplest models have performed compared to observed climate change[12]. We *can* predict the big picture of climate change (and do so very successfully) – it’s the regional and small-scale changes that are less easy to predict. Georg Feulner Senior Scientist, Potsdam Institute for Climate Impact Research (PIK): Curry’s claim: Climate scientists disagree about the most consequential issues: how much warming is associated with our emissions, and whether this warming is larger than natural climate variability The first part of this statement is misleading, the second part is just wrong. Concerning the first part, the amount of warming associated with emissions is characterized by the climate sensitivity, i.e. the long-term warming after a doubling of the carbon-dioxide levels above pre-industrial concentrations. The latest IPCC assessment puts the climate sensitivity in a likely range of 2.5 to 4 degrees (high confidence)[1], so while we do not know precisely how much Earth will warm under continuing emissions, we are sure that it will warm. Concerning the second part of the statement, the warming already observed in the instrumental record has left the range of natural climate variability. Curry’s claim: “Variations in the sun and volcanic eruptions also have a substantial impact [on Earth’s climate], but these are simply unpredictable” – This statement overemphasizes the role of the sun and volcanic eruptions. Solar variability leads to fluctuations of Earth’s global mean surface temperature of about 0.1 degrees, compared to about 1.3 degrees of warming since the pre-industrial era. Volcanic eruptions can cool the climate by a few tenths of a degree for a couple of years[13], but this is only a short-term effect compared to the long-term warming by human greenhouse gas emissions. And the fact that we cannot predict the future behavior of the sun and volcanoes does not imply that we cannot include their effect in a statistical sense in future projections – in which the temperature change is dominated by human emissions in any case. Comments on other statements in the video: Curry’s claim: “inadequate climate models driven by unrealistic assumptions” Climate models are constantly improved and extensively validated against present-day observations and past climate change. They are based on our best knowledge of the physical, chemical, and biological processes in the Earth system and driven by measured (or reconstructed) input data (e.g. on greenhouse gas concentrations) in the past, and scenarios for future emissions for projections. While the models are not perfect (they would not be models, then), they provide important information about future climate change. Climate scientists typically compare the projections of many models to be able to assess robustness and quantify model uncertainty. On the Lake Chad example – one very specific counterexample of environmental change not caused by climate change does not disprove the multitude of expected negative climate change impacts around the world."
https://science.feedback.org/review/carbon-isotopes-do-not-show-humans-climate-impacts-too-small-notice-despite-the-daily-sceptic-inaccurate-claim/,Incorrect,"Daily Sceptic, Chris Morrison, 2024-04-08",Human-caused carbon emissions’ effect on climate is ‘non-discernible’. Measurements of carbon isotope ratios in atmospheric CO2 indicate that it is the recent expansion of a more productive biosphere that has led to increased CO2 concentrations in the atmosphere.,,"Incorrect: Scientific studies demonstrate that fossil fuel emissions are the only cause that can explain both changes in carbon isotope ratios and increased CO2 concentrations in the atmosphere. Cherry-picking: The article supports its claim with only two papers while ignoring the vast body of existing evidence that disproves it. The two papers in question are written by authors with no background in climate science and have been debunked by scientists who showed that they relied on flawed methodologies and made fundamental errors. For example, a more productive biosphere would be a net carbon sink and therefore decrease CO2 concentrations in the atmosphere, rather than increasing them.","Carbon isotope ratios are actually one of the key measurements that show human-caused emissions are responsible for climate change. CO2 emissions from fossil fuels have lower concentrations of both carbon-13 and carbon-14 than CO2 placed in the atmosphere by the natural carbon cycle. Therefore, burning fossil fuels is linked to decreased concentrations of both isotopes in atmospheric CO2.",“Human-caused carbon emissions’ effect on climate is ‘non-discernible’. Measurements of carbon isotope ratios in atmospheric CO2 indicate that it is the recent expansion of a more productive biosphere that has led to increased CO2 concentrations in the atmosphere.”,"1 – Graven et al. (2020) Changes to Carbon Isotopes in Atmospheric CO2 Over the Industrial Era and Into the Future. Global Biogeochemical Cycles. 2 – Hoffman and Rasmussen (2022) Absolute Carbon Stable Isotope Ratio in the Vienna Peedee Belemnite Isotope Reference Determined by 1H NMR Spectroscopy. Analytical Chemistry. 3 – Graven et al. (2017) Compiled records of carbon isotopes in atmospheric CO2 for historical simulations in CMIP. Geoscientific Model Development. 4 – Ritchie et al. Key Insights on CO2 and Greenhouse Gas Emissions. Our World in Data. 5 – Clark et al. (2021) SuessR: Regional corrections for the effects of anthropogenic CO2 on δ13C data from marine organisms. Methods in Ecology and Evolution. 6 – Francey et al. (1999) A 1000-year high precision record of δ13C in atmospheric CO2. Tellus B. 7 – Böhm et al. (2002) Evidence for preindustrial variations in the marine surface water carbonate system from coralline sponges. Geochemistry, Geophysics, Geosystems. 8 – Shervette et al. (2021) Radiocarbon in otoliths of tropical marine fishes: Reference Δ14C chronology for north Caribbean waters. PLOS One. 9 – Xiong et al. (2021). Time series of atmospheric Δ14CO2 recorded in tree rings from Northwest China (1957–2015). Chemosphere. 10 – Graven (2015) Impact of fossil fuel emissions on atmospheric radiocarbon and various applications of radiocarbon over this century. Proceedings of the National Academy of Science. 11 – Yu et al. (2022) Estimation of Atmospheric Fossil Fuel CO2 Traced by Δ14C: Current Status and Outlook. Atmosphere. 12 – Watson et al. (1990) Greenhouse Gases and Aerosols. Climate Change: The IPCC Scientific Assessment. 13 – Canadell et al. (2003) Global Carbon Budget 2023. Earth System Science Data. 14 – Suess (1955) Radiocarbon Concentration in Modern Wood. Science. 15 – Keeling (1979) The Suess effect: 13Carbon-14Carbon interrelations. Environment International. 16 – Anderegg et al. (2010) Expert credibility in climate change. Proceedings of the National Academy of Sciences.","Carbon comes in three naturally occurring isotopes on Earth: carbon-12, carbon-13, and carbon-14. Different carbon sources bear different mixtures of the three, and studying these isotopic signatures can help trace how carbon moves across the Earth. For instance, carbon-13 and carbon-14 are less abundant in fossil fuels than in atmospheric CO2, but the concentrations of the two isotopes in atmospheric CO2 have both dropped since the mid-20th century. A large body of scientific evidence has long attributed these declines to extra CO2 pumped into the atmosphere by humans burning fossil fuels[1]. An article authored by Chris Morrison in The Daily Sceptic, an outlet with a track record of scientifically unfounded messages, makes a conflicting claim: that changing isotope signatures in atmospheric CO2 result from the biosphere, rather than human causes like fossil fuel emissions. The article primarily cites “a new paper” published in February 2024 and supports its claim with a second paper published two years earlier. The article then upholds the two papers’ findings as scientific evidence that the human impact on climate change is “non-discernible”. Below, however, we show that the Daily Sceptic builds its claim on a scientifically shaky foundation. The two papers are at odds with decades of scientific results showing that these isotope changes are the direct result of CO2 emissions from human activity. Furthermore, both papers have received heavy criticism from climate scientists for drawing their conclusions from faulty analyses. Additionally, scientists contacted by Science Feedback emphasized that isotope concentrations are far from the only evidence pinning human activity as the primary cause of increased CO2 in the atmosphere. claim 1 (INCORRECT):A lack of carbon-13 is the biosphere’s problem The Daily Sceptic draws the core of its argument from a paper (“the Sci paper”) published in February 2024 in Sci, a journal published by MDPI, which has a reputation as a “predatory” publisher. The Sci paper analyzed historic data showing a decline in the ratio of carbon-13 to carbon-12, the element’s two stable isotopes, and blamed the change not on fossil fuel emissions but on a “more productive and expanded” biosphere. The carbon-13 to carbon-12 ratio is a common measurement in climate science. Carbon-12 accounts for about 99% of Earth’s carbon, and carbon-13 takes up almost all of the remaining 1%. Depending on the origin, the exact concentrations of each vary by a few fractions of a percent (Fig. 1). Climate scientists gauge these variations with δ13C, the deviation of a sample’s ratio of carbon-13 to carbon-12 from a standard benchmark originally derived from a particular type of limestone[2]. In other words, the lower a sample’s δ13C, the higher its carbon-12 content. Figure 1 – The δ13C values of different carbon sources and sinks. Note that fossil fuels have a distinctly lower δ13C than CO2 in the atmosphere and that the modern atmosphere has a lower δ13C than the atmosphere of only several hundred years earlier. Source: Graven et al. 2020[1] δ13C is a telling indicator when used to measure CO2 in the atmosphere (δ13CO2). Plants prefer to photosynthesize carbon-12, making the biosphere’s δ13C lower than δ13CO2. By extension, fossil fuels made from ancient biological matter also hold more carbon-12; when humans burn those fossil fuels, it also releases CO2 with lower δ13C than δ13CO2. The consequences are observed globally: δ13CO2has declined since the beginning of the Industrial Revolution (Fig. 2). Analyses have shown that, after accounting for exchanges between carbon in the atmosphere and carbon in the ocean and terrestrial biosphere, this decline matches the expected change from known fossil fuel emissions[1]. Figure 2 – Several measurements of δ13C from 1850 to 2015. The decline beginning in the late 20th century corresponds to a rise in anthropogenic CO2 emissions. Source: Graven et al. 2017[3] Instead, the Sci paper tried to explain the decline with a scenario that entirely ignored fossil fuel emissions. The paper attempted to calculate the relationship between CO2 and δ13CO2between 1520 and 1997 and noted that both measurements exhibited seasonal cycles as Earth’s biosphere became more active in the Northern Hemisphere spring, then declined in the Northern Hemisphere winter. The Sci paper then used this observation to claim that δ13CO2declined as a consequence of Earth naturally warming since the end of the Little Ice Age in about 1800, which the paper argues boosted the carbon cycle of the planet’s biosphere. The paper claimed the biosphere pumped low-δ13C greenhouse gas into the atmosphere, causing both a δ13CO2 decline and a rise in atmospheric CO2 levels. When Science Feedback asked scientists who studied isotope ratios to comment on the Sci paper, they pinpointed flaws in the paper’s methodology. For instance, although it is true that CO2 activity follows seasonal cycles, the paper’s model neglected to include several key processes impacting δ13CO2. The paper treated the atmosphere as a closed CO2 reservoir, ignoring two-way exchanges with the oceans and terrestrial biosphere that allow isotopic perturbations in the atmosphere to dissipate. More egregiously, the paper explicitly cited the known CO2 emissions from fossil fuels and their isotopic signature[4], then excluded them from its analysis and dismissed them as a driver of CO2 concentration and δ13CO2changes. “What is frustrating and confusing to me is that the author knows that human emissions have increased significantly during the industrial period, enough to explain the rise of CO2,” Sourish Basu, a research scientist at NOAA Global Monitoring Laboratory and an expert in carbon cycle, told Science Feedback in an email. “Early on, the author erroneously concluded that the biosphere must be the main driver behind the atmospheric CO2 budget and fossil fuel emissions must be negligible.” Heather Graven, a climate physicist at Imperial College London, echoed this criticism of the Sci paper. “What he does is he just tries to estimate the isotope composition of the source using a flawed method,” she told Science Feedback via telephone. “He doesn’t really perform a simulation taking into account all the factors.” Basu and Graven also questioned the validity of the Sci paper’s conclusion. “What we see in the atmosphere is because the biosphere and the oceans take up half of our emitted fossil CO2. The biosphere is a net sink, not a net emitter. The author gets this basic fact wrong,” Basu told Science Feedback. Therefore, the scenario that a more productive biosphere could simultaneously push down δ13CO2 and increase the amount of CO2 in the atmosphere makes little sense. “If [the carbon-12] were coming from the biosphere, we would have had to lose carbon,” Graven told Science Feedback. The Daily Sceptic derives the core of its claim from a paper that begins with flawed assumptions and uses a flawed model. Essentially, the paper ignores fossil fuel emissions to argue that they are not the root cause of declining δ13CO2. The paper then uses this flawed model to conclude that the biosphere is responsible for pumping CO2 into the air at unprecedented rates, something that contradicts the majority of available evidence. Meanwhile, numerous studies have explained that measurements of declining δ13CO2 correlate with and are caused by an increase in anthropogenic CO2 from fossil fuel emissions[5-7]. claim 2 (incorrect):Carbon-14 shows that fossil fuels emissions are a drop in the bucket The Daily Sceptic supports its erroneous claim by citing a second paper (“the Health Physics paper”), published in February 2022 in the journal Health Physics, a publication that has no significant relevance to climate science. The Health Physics paper examines carbon-14 data to conclude that fossil fuels are responsible for only a small fraction of atmospheric CO2. Climate scientists do use carbon-14 as an indicator. The isotope is extremely rare: about one in every 1012 carbon atoms is a carbon-14 atom. Carbon-14 is radioactive, with a half-life of about 5,700 years, meaning that fossil fuel carbon, which is hundreds of millions of years old, contains almost no carbon-14 whatsoever (Fig. 3) Therefore, the absence of carbon-14 is a flag for the presence of fossil fuel emissions. Figure 3 – The Δ14C values of different carbon sources and sinks. Note, again, that fossil fuels have a distinctly lower Δ14C than CO2 in the atmosphere. Thanks to nuclear weapons testing, atmospheric Δ14C in the modern day is higher than prior to the 20th century. Graven et al. 2020[1] Specifically, climate scientists use a measure called Δ14C, which is calculated from how much a sample’s carbon-14 concentration varies from that of atmospheric air prior to the invention of nuclear weapons[8]. A lower Δ14C indicates that less carbon-14 is present. In the 1950s and 1960s, carbon-14 released as fallout from nuclear weapons tests caused the Δ14C of atmospheric CO2 (Δ14CO2) to dramatically spike. But after the Partial Nuclear Test Ban Treaty largely ended above-ground tests in 1963, Δ14CO2began to decline just as drastically (Fig. 4). Figure 4 – Measurements of Δ14CO2over time. The decline beginning in the 1960scentury corresponds to the end of nuclear weapons testing and a large increase in human CO2 emissions. Source: Xiong et al. 2021[9] However, Δ14CO2 declined too quickly to be explained by carbon-14 decaying or being exchanged out of the atmosphere, indicating that carbon-14-free CO2 entered the atmosphere from fossil fuel emissions[1]. Multiple studies have clearly demonstrated that anthropogenic fossil fuel emissions are responsible for the ongoing decline in Δ14CO2[10,11]. The Health Physics paper’s three authors, none of whom have an obvious climate science background, created a model to match data on Δ14CO2 dating from between 1750 and 2018. Their model assumed that fossil fuel CO2 contained zero carbon-14 and that any given volume of CO2 cycled out of the atmosphere in about 4 years. The authors’ analysis determined that fossil fuel emissions only accounted for 12% of global CO2 as of 2018. The authors, then, concluded that fossil fuels could not have driven modern-day climate change. Like the Sci paper, the Health Physics paper garnered criticism from scientists for making false assumptions. One published comment in the same journal pointed out a major flaw in the Health Physics paper’s methodology: It conflated atmospheric CO2’s residence time (the amount of time a CO2 molecule actually spends in the atmosphere before being exchanged with the land or the water, which is about 4 years) with its adjustment time (the amount of time an extra volume of CO2 will stay in the atmosphere, which can be millennia). As a result, the Health Physics paper authors drastically underestimated how long fossil fuel CO2 would stay in the atmosphere. This is not a new error; as early as 1990, an IPCC report warned researchers against making it[12]. Furthermore, the comment stated, “Throughout [the Health Physics paper] the authors have failed to cite numerous related and relevant earlier publications in this field and demonstrated a lack of fundamental understanding of biogeochemical carbon cycle processes,” the comment stated. A second comment from a different group, published in the same journal, explained that — in addition to conflating residence time with adjustment time — the Health Physics paper used faulty Δ14CO2data and inadequately addressed the role of carbon-14 from nuclear weapons testing that remained in the atmosphere into the 21st century, both of which led them to further underestimate the fossil fuel contribution to Δ14CO2trends. This comment demanded that Health Science retract the paper, which the journal has not done. Much like the Sci paper, the Health Physics paper derived its conclusions from a flawed methodology. Moreover, the paper ignores that the volume of CO2 from fossil fuel emissions and its impact on the atmosphere at large are both very well-documented from methods such as air sampling[4]. The concentration of CO2 in the atmosphere has risen from about 280 parts per million (ppm) prior to the Industrial Revolution to about 420 ppm today; the Global Carbon Budget attributed about two-thirds of the excess to fossil fuel emissions and the remainder to human-caused land use changes like deforestation[13]. The body of evidence points to fossil fuel emissions as the culprit for atmospheric CO2 rise Despite the two papers’ flaws and their public debunking by scientists, the Daily Sceptic article champions them to assert a lack of a “discernible” human fingerprint on the climate and claims that carbon isotope signatures are an “interesting branch of climate science to investigate”. The reality is that it has been thoroughly investigated for decades. The study of carbon isotope ratios, in fact, predates any scientists reaching consensus about climate change. As early as the 1950s, chemist Hans Suess measured carbon-14 concentrations in wood and connected them to carbon-14-free fossil fuel emissions released starting from the Industrial Revolution[14]. By the late 1970s, climate scientists had measured shifts in δ13CO2and Δ14CO2 matched the predicted changes caused by then-known CO2 emissions[15]. It may be prudent to look at the isotope ratio changes in the bigger picture. We need a culprit that can explain all of the changes we have observed: a culprit that has lower δ13C than atmospheric CO2, a culprit that is sufficiently old for its carbon-14 levels to have decayed to effectively zero, and a culprit that can explain the dramatic increase in atmospheric CO2 concentrations since the industrial revolution. According to Basu, this allows us to rule out alternative carbon sources like volcanic outgassing, for example, which has a high δ13C; instead, the only suitable suspect is the emissions from humans burning fossil fuels. Moreover, the study of isotope ratios is only one branch of many clearly pointing at a human origin for climate change. Supporting this idea, Ralph Keeling, a climate scientist at the Scripps Institute of Oceanography, told Science Feedback in an email: “We don’t need to turn to measurements of isotopes to establish that the CO2 rise is caused by humans. In fact, we know quite well how much CO2 we’ve dumped into the atmosphere over the past 150 years through the burning of fossil fuels, and it’s more than enough to account for the observed rise. The rise started at the time of the dawn of the industrial revolution, and has accelerated since then. Overall, the CO2 rise is a bit similar to the buildup of trash in a landfill. The trash is obviously of human origin, because we know we put it there. There’s not much sense in questioning its human origins.” Indeed, scientists have clearly identified human causes as responsible for all of modern climate change activity[16], as Science Feedback has previously covered."
https://science.feedback.org/review/data-shows-temperatures-rising-greenland-world-current-global-warming-driven-co2-not-solar-activity/,Inaccurate,"Daily Sceptic, Stephen Andrews, 2024-03-08"," Ice cores from Greenland show no significant warming, casting doubt on the climate change theory",,"Factually inaccurate: The claim that there is no global warming signal from Greenland is in direct contradiction with available observations. Recent studies of ice cores from several locations in Greenland have shown that temperatures are warming faster than the natural variation of the last 1000 years. Rising temperatures in Greenland do not necessarily represent global changes. However, other studies have shown evidence of rising temperatures around the world.  Unsupported: There is no evidence to support that solar cycle variation has a greater impact on rising global temperatures than increasing atmospheric CO2. In fact, solar intensity is currently declining while global temperatures are rising. Evidence shows that rising atmospheric CO2 from human activities is the primary driver of modern global warming.  Cherry-picking: Ice core data from one location in Greenland is insufficient to represent the entire planet. Numerous recent studies with larger data sets and rigorous statistical analysis show a global warming trend around the world. ","The effect of atmospheric CO2 concentrations on global temperatures is well established; as concentrations rise, global warming increases through the greenhouse effect. Scientific studies show that modern global warming is primarily driven by increasing CO2 emissions from human activities. Based on the available scientific evidence, solar variation has had no significant effect on modern global warming compared to rising atmospheric CO2 concentrations.","Ice cores from Greenland show no significant warming, casting doubt on the climate change theory; above a certain concentration of carbon dioxide, it has minimal direct impact on global temperature relative to solar cycles.","1 – Anderegg et al. (2010) Expert credibility in climate change. Proceedings of the National Academy of Sciences. 2 – Markle and Steig (2022) Improving temperature reconstructions from ice-core water-isotope records. Climate of the Past. 3 – Holme et al. (2019) Varying regional δ18O–temperature relationship in high-resolution stable water isotopes from east Greenland. Climate of the Past. 4 – Hörhold et al. (2023) Modern temperatures in central–north Greenland warmest in past millennium. Nature. 5 – Kaufman et al. (2020) Holocene global mean surface temperature, a multi-method reconstruction approach. Nature. 6 – IPCC (2021). Sixth Assessment Report. 7 – PAGES 2K Consortium (2019) Consistent multidecadal variability in global temperature reconstructions and simulations over the Common Era. Nature Geoscience. 8 – Santer et al. (2013). Human and natural influences on the changing thermal structure of the atmosphere. Proceedings of the National Academy of Sciences. 9 – Pierce and Adams (2009) Can cosmic rays affect cloud condensation nuclei by altering new particle formation rates?. Geophysical Research Letters 10 – Zhong and Haigh (2013) The greenhouse effect and carbon dioxide. Royal Meteorological Society Weather. Note: Scientists comments were lightly edited for clarity (i.e., information was added in brackets for context and minor punctuation changes were made).","The consensus among climate scientists is that modern global warming is primarily driven by increases in atmospheric CO2 from human activities[1]. A major component of studying global warming is comparing present conditions with those of the past. However, taken out of context, these data can be misinterpreted to draw conclusions that are inaccurate and unsupported. A recent example is in an article on The Daily Sceptic, which made several claims about global warming using a small subset of the available climate data, which we will investigate below. Based on ice core data from one part of Greenland, the article claims that “there is no significant global warming signal coming from one of the most sensitive parts of the planet”, and that these data–which show a rising temperature trend in modern times–fall within a normal (natural) variation. However, this claim is in direct contradiction with scientific findings, mischaracterizes the cited data, and excludes sufficient context about how global warming trends are studied. Evidence of Rising Temperatures in Greenland Scientists use climate proxies, such as ice cores, to help them reconstruct past conditions. For example, stable water isotope (δ18O) signals from ice cores can be used to determine past local temperatures[2]. This method was employed in the studies referenced by The Daily Sceptic article. However, the article leaves out critical details about the uncertainties in the data and mischaracterizes the findings. One study the article references has proxy data from 10,000 BCE to 1960 CE; however, this period excludes several recent decades of available climate data. The second paper the article references, Holme et al. (2019), studied proxy data from 1801-2014, which, as the article correctly points out, shows a rising trend in the δ18O signal. However, the article excludes an important conclusion from the study: “the linear δ18O–temperature relationship was unstable with time which implied that the annual-to-decadal variability of δ18O measured in an ice core could not be directly attributed to temperature variability.”[3] Therefore, there is less certainty when using these data to assess Greenland temperature trends over recent decades. There is a study, however, that analyzed recent temperature trends in Greenland compared to natural variation–the main topic of The Daily Sceptic article. Hörhold et al. (2023) analyzed ice core data from central and northern Greenland–a larger study area–to create a high-quality temperature reconstruction for the period of 1000-2011[4]. The study showed that “the warming in the recent reconstructed decade exceeds the range of the pre-industrial temperature variability in the past millennium with virtual certainty (P < 0.001)”[4] (Figure 1). The authors had greater confidence in these temperature trends due to the high correlation between the δ18O data and local temperature data–which was lacking in the Holme et al. (2019) study. Figure 1 – The top graph (solid black line) shows the record of δ18O and the inferred temperature time series from 1000-2011. Existing ice core data was extended to 2011 in this study by re-drilling ice cores–this data is highlighted in red on the top graph. Two trends from these data–1000 to 1800 and 1800 to 2011–are shown as black dashed lines. The number of firn cores used to collect the data are shown as a thin brown line below the top graph. The bottom blue graph represents arctic-wide data (not discussed here). Source: Hörhold et al. (2023)[4] Based on these findings, the claim made in The Daily Sceptic article regarding a lack of global warming signal from Greenland is inaccurate and a mischaracterization of the supporting data. The Hörhold et al. (2023) study–which analyzed more ice core data (with greater spatial coverage) and achieved high data correlation–found clear evidence of warming in Greenland which exceeded the natural variation of the last 1000 years[4]. Evidence of Rising Global Temperatures While proxy data from one location can be used to reconstruct past local temperatures, it is not necessarily sufficient to reconstruct past global temperatures. To explain this, Dr. Joanna Haigh, Emeritus Professor of atmospheric physics at Imperial College London, provided Science Feedback with the following comment about the article: “using one location to represent global warming is invalid. He [the author] refers to Greenland [as] being the most sensitive place without saying how that is defined. There is substantial evidence of larger variations in temperature at different locations [e.g. Dansgaard-Oescher events]. These are not fully understood but are not used to make statements on global parameters.” To better understand global climate change and reduce uncertainty in their studies, scientists use a variety of methods and analyze a greater number of samples. The Daily Sceptic article only cites data from one area in Greenland; however, there are studies which used more proxies and methods to reduce uncertainty. For example, a study by Kaufman et al. (2020) used 679 proxy sites (Figure 2) and five different statistical methods when reconstructing global mean surface temperatures (GMST) for the last 12,000 years[5]. This multi-method approach helped the researchers create an ensemble of global temperature reconstructions that account for the uncertainties of the different methods. By increasing the number of samples and locations they analyze, researchers also have greater confidence that the results better represent global changes, rather than local changes. Figure 2 – Locations of the 679 proxy data sites (green dots) for the 12,000 year temperature reconstruction. Source: Kaufman et al. (2020)[5] The Kaufman et al. (2020) study indicated that there were periods of cooling and fluctuation over the last 12,000 years (Holocene); however, it also showed a modern rise in global warming[5]. As the authors explain, “The distribution of peak global temperatures during the Holocene can also be compared with recent temperatures. The GMST of the past decade (2011–2019) averaged 1°C higher than 1850–1900. For 80% of the ensemble members, no 200-year interval during the past 12,000 years exceeded the warmth of the most recent decade.”[5] The results of this study (Figure 3) show that a rising global warming trend began in the industrial era and has continued to the present day. Figure 3 – Global mean surface temperature over 12,000 years using multiple reconstruction methods. The fine black line shows instrumental data collected from 1900 to 2010. The smaller inset graph shows the most recent 2000 years of data. Source: Kaufman et al. (2020)[5] Kaufman et al. (2020) explain that the comparisons they made between 200-year intervals of the Holocene and modern warming are conservative in the context of IPCC projections, which indicate that temperatures are likely to rise higher than 1°C above pre-industrial temperatures in the next century[5]. They then explain that the IPCC projections give a better comparison between warming in recent decades and the temperatures in the Holocene reconstructions. A number of other studies have also shown evidence that modern global warming trends are unusual compared to past variations. According to The Intergovernmental Panel on Climate Change (IPCC), the world’s leading authority on climate science, the last 1000 years of temperature data and their methods of reconstruction have been well-studied[6]. One of the studies the IPCC refers to, PAGES 2K Consortium (2019), explains that “the largest warming trends at timescales of 20 years and longer occur during the second half of the twentieth century, highlighting the unusual character of the warming in recent decades.”[7] Rising CO2 Has Driven Global Warming, Not Solar Cycle Variability The Daily Sceptic article also claimed that a lack of global warming signal from the data he provided “could be explained by the fact that the relationship of carbon dioxide to global temperature is logarithmic and above a certain concentration there is minimal direct impact relative to solar cycles.” However, this claim is inconsistent with available evidence. In fact, Science Feedback has done several investigations of similar claims about solar influence on climate change, a sample of which are linked below: Review: 1: The sun isn’t responsible for current climate change, contrary to claims in Suspicious0bservers YouTube video Review 2: Low solar activity has little effect on Earth’s climate, contrary to claim in The Sun Review 3: Claim that current climate change can be explained satisfactorily by natural cycles and volcanic activity does not have scientific support These reviews provide several lines of evidence that solar activity is not driving the rise in global temperatures. For example, one review explains that if the Sun were driving global warming, we should see temperatures rising at the surface of the Earth and throughout the Earth’s atmosphere. Instead, the data show Earth’s surface heating up, while the layers of the atmosphere are changing variably–lower altitudes heating, and higher altitudes cooling[8]. Another review found that the rate and magnitude of modern global warming is too high to be caused by solar variations[9]. The physics of both solar cycle variation and atmospheric CO2 are well understood. The IPCC explained that solar activity from the late 19th century to present was not exceptional compared to the last 9,000 years[6]. The IPCC also compared observed temperature changes to models that accounted for both human and natural influences (Figure 4). As shown below, in both the observed data and simulated cases, the addition of human drivers–such as CO2 emissions–lead to a greater rise in global temperatures. Figure 4 – Observed and simulated changes in global surface temperature from 1850 to 2020. The black line represents 170 years of observed and averaged data and is compared to Coupled Model Intercomparison Project Phase 6 (CMIP6) climate model simulations. The brown area represents the temperature response to both human and natural drivers and the green area to only natural drivers (solar and volcanic activity). Solid colored lines represent the averages, and the shaded areas represent the very likely range for the models. Source: IPCC (2021)[6] After reviewing the Daily Sceptic article’s claim about solar variability, Dr. Joanna Haigh provided the following comment: “He [the author] does not define ‘solar cycle’, normally used to refer to [the] 11-year activity cycle; he presumably means longer term solar activity which is currently declining so [it] can’t explain recent global warming.” And in response to the article’s claim of diminishing CO2 impacts, Dr. Haigh commented “Fig.6 in the paper [Zhong and Haigh (2013)] shows logarithmic response in radiative forcing of temperature to CO2 increase – but still rising. In that paper we used 389 ppm [parts per million] as [the] current CO2 concentration. It is now 425 ppm – higher than for millions of years and rising unremittingly.” Dr. Haigh’s explanation highlights that atmospheric CO2 concentration is increasing, and despite the response being logarithmic, global temperatures are, and will continue, rising with increasing CO2 (Figure 5). Figure 5 – Radiative Forcing of CO2 (relative to the atmospheric CO2 concentration of 389 ppm–the concentration at the time of the study). Source: Zhong and Haigh (2013)[10] In other words, the study shows that radiative forcing–the effect of Earth’s atmosphere receiving more energy from solar radiation that it emits back out to space–lessens gradually with increasing CO2 concentrations, but remains positive[10]. The Zhong and Haigh (2013) paper concludes that as CO2 increases in the atmosphere, there is no saturation point at which it will no longer cause radiative forcing–therefore, it will continue to be a factor in global warming. Conclusion: As shown above, the claims that the Daily Sceptic article made about Greenland temperature trends, global warming signals, CO2, and solar cycles are incorrect and unsupported. Scientific evidence on these subjects shows the following: temperatures in Greenland and around the world are rising, the primary driver is increasing atmospheric CO2 from human emissions, and solar variation has had no significant effect on rising modern global temperatures. Although the response is logarithmic, as CO2 concentrations increase, so will global temperatures. This is evident based on climate models and the physics of CO2, which are well understood. After analyzing and modeling the drivers of climate change, the IPCC found no evidence that solar variation can account for the rising trend of global temperatures. Several studies, which reviewed up to 10,000 years of climate proxy data, show that the current rate of global warming is unusual compared to past natural variations."
https://science.feedback.org/review/arctic-sea-ice-melting-over-past-decades-with-projections-summer-ice-free-conditions-mid-century/,Incorrect,"The Epoch Times, Allan Astrup Jensen, 2024-02-06","Arctic sea ice is not melting and there is no indication that we should expect the Arctic sea summer ice to disappear completely, as predicted",,"Incorrect: Overall, Arctic sea ice extent and volume have been decreasing since the 1970s, a trend that scientists largely attribute to human-induced global warming. The author of the claim cherry-picks short term fluctuations due to natural variability to suggest otherwise. Scientists forecast the first ice-free summer for the 2050s.","Despite short-term fluctuations due to natural variability, the Arctic sea ice extent and volume has decreased over the past few decades. Scientists have established that this decrease is mostly the result of global warming due to human emissions of greenhouse gasses.","Arctic sea ice is not melting. There is no indication that we should expect the Arctic Sea summer ice to disappear completely, as predicted. CO2 levels don't drive Arctic sea ice decline.","1 – IPCC (2021) Ocean, Cryosphere and Sea Level Change. In Climate Change 2021: The Physical Science Basis. Contributions of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. 2 – Walsh et al. (2017) A database for depicting Arctic sea ice variations back to 1850. Geographical Review. 3 – Polyak et al. (2010) History of sea ice in the Arctic. Quaternary Science Reviews. 4 – Kinnard et al. (2011) Reconstructed changes in Arctic sea ice over the past 1,450 years. Nature. 5 – Halfar et al. (2013) Arctic sea-ice decline archived by multicentury annual-resolution record from crustose coralline algal proxy. Proceedings of the National Academy of Sciences. 6 – Johannessen et al. (2004) Arctic climate change: observed and modelled temperature and sea-ice variability. Dynamic Meteorology and Oceanography. 7 – Eyring et al. (2021) Human Influence on the Climate System. In Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. 8 – Perovich et al. (2007) Seasonal evolution and interannual variability of the local solar energy absorbed by the Arctic sea ice–ocean system. Geophysical Research Letters. 9 – Stroeve et al. (2014) Changes in Arctic melt season and implications for sea ice loss. Geophysical Research Letters.","Since the 1970s, satellites have been providing accurate measurements of sea ice extent in the Arctic, revealing a steady reduction in its surface. The yearly extent of Arctic sea ice that survives the entire summer has decreased by approximately 50% from 1979 to 2020 compared to its average extent during the period from 1981 to 2010. Under all Intergovernmental Panel on Climate Change (IPCC) scenarios, even the most optimistic one, the Arctic Sea is expected to reach a mostly ice-free state during some years in the summer as early as the 2040s. An article by The Epoch Times dated 6 February 2024 disseminated claims challenging the scientific observations of declining arctic sea ice and predictions of an ice-free summer in the Arctic, drawing on assertions from a single report and remarks by an independent consulting engineer. Arctic sea ice has been shrinking for decades The title of The Epoch Times article falsely claims that ‘the UN Says Melting Arctic Ice Is Key Indicator of Climate Change—But It’s Not Melting’. This statement is inaccurate, as scientific evidence consistently shows that Arctic sea ice is indeed melting and serves as a critical indicator of climate change. Arctic sea ice grows and shrinks with the seasons, melting from around March to September and reforming in the cold winter months. Scientists study the yearly minimum extent of Arctic sea ice because it provides critical insights into its seasonal cycle and its response to environmental changes. This measurement, taken at the end of the summer melting season, indicates the quantity of sea ice remaining. Satellite records have shown that Arctic sea ice extent has steadily declined over the last four decades. In the 1980s, the September average extent represented close to 50% of the March average; from 2013 to 2022, the ratio was only 35%. Reaching lower minimums indicates a weaker recovery in winter, showing that the Arctic is losing ice and failing to replenish it. In addition, this trend is further reinforced by the fact that sea ice volume is also decreasing. The IPCC notes that: “Current best estimates from reanalyses indicate that September Arctic sea ice volume has reduced by about 72% over the period from 1979 to 2016, […] a conservative estimate.”[1] Regarding the trend from the 2010s onwards, the IPCC explains in its report that there is “low confidence in the amount of decrease over this period […] primarily because of snow-induced uncertainties in the retrieval algorithms, the shortness of the record, and the small identified trend.” Arctic sea ice is forecasted to continue melting The Epoch Times article quotes a report by Allan Astrup Jensen, a chemical risk assessment specialist, claiming that “in the last 17 years, from 2007 to 2023, the [Arctic sea ice extent] downward trend has also been about zero […] Therefore, there is no indication that we should expect the Arctic Sea summer ice to disappear completely, as predicted, in one or two decades.” This assertion contradicts the majority of scientific literature on the subject projecting ice free summers later this century, which represents the best evaluation of human knowledge on the topic. Synthesizing this research, the IPCC reports that the current Arctic sea ice extent, both annually and during the late summer, is at its lowest level since at least 1850, with high confidence. In the same fact-sheet the IPCC states that, under all considered scenarios, the Arctic is expected to reach practically ice-free conditions at its summer minimum at least once before 2050. While Arctic sea ice extent has not declined at a constant rate from 1979 to 2007, the short term fluctuations do not invalidate the overall downward trend (see gray line in Figure 1) and the continued impact of warming expected in the future due to climate change. The last 17 Arctic sea ice yearly minimum extents are the lowest in the satellite record and summer Arctic sea ice loss since 1979 is unprecedented in 150 years, based on historical reconstructions[2] and more than 1000 years of paleoclimate evidence[3,4,5]. Figure 1 – Arctic Sea ice extent as measured by satellites between 1978 and 2022. The long-term trend for 1979 to 2021 is shown by the dashed gray line, while trends over shorter periods are shown in colors: red for 1979 to 1992, blue for 1993 to 2006, and dark green for 2007 to 2021. (source) How increasing CO2 concentrations impact Arctic sea ice? In The Epoch Times’ article, engineer Frank Geisel claims that we do not know whether increased atmospheric CO2 concentrations are driving a decline in sea ice extent and volume. The Epoch Times article’s author picks two CO2 concentration levels and Arctic minimum sea ice extent (in 1979 and 1996) that supposedly supports this claim. However, a physical connection between the two variables cannot be established or dismissed by just cherry-picking two data points, one has to look at all the available evidence and understand the physical mechanism explaining the connection. As explained below, scientists have established that human-induced climate change causes a decline in Arctic sea ice through various scientific observations and analyses. Firstly, observational data have shown a clear trend of shrinking sea ice extent and thickness, especially noticeable each September when the ice reaches its annual minimum. Model simulations show this decline correlates closely with rising global temperatures and increased greenhouse gas emissions, consistent with a direct link between increased greenhouse gases concentrations and diminishing sea ice[6]. The IPCC concluded that “it is very likely that anthropogenic forcing mainly due to greenhouse gas increases was the main driver of Arctic sea ice loss since 1979.”[7] Secondly, studies of the Arctic’s energy balance provide further evidence. Sea ice has a high albedo, meaning it reflects a significant amount of solar energy back into space. As climate change leads to warmer temperatures, sea ice melts, exposing darker ocean water that absorbs more solar energy, leading to further warming and ice loss in a reinforcing feedback loop. This mechanism, well-documented by climate scientists, further demonstrates how increased temperatures from greenhouse gasses directly contribute to the reduction of Arctic sea ice[8]. Lastly, the timing of the melt season has shifted, with ice melting earlier in the spring and freezing later in the fall, further supporting the impact of rising temperatures on sea ice[9]. Records show that increasing global temperatures are happening in tandem with increasing levels of carbon dioxide (see Figure 2, top), while the Arctic has been warming at an even faster rate than the rest of the globe (see Figure 2, bottom), which contributes to Arctic sea ice melting. Figure 2 – Top: yearly temperature anomalies compared to the twentieth-century average (red and blue bars) from 1880 to 2019, based on data from NOAA NCEI, and atmospheric carbon dioxide concentrations (gray line): 1880-1958 from IAC, 1959-2019 from NOAA ESRL (source).Bottom: cumulative/net trend in combined sea and ice surface temperature anomalies for the Arctic Ocean from 1993 to 2022. The cumulative trend is the rate of change (°C/year) scaled by the number of years (30 years). Based on satellite observations from the E.U. Copernicus Marine Service Information (source). Not all the decrease in Arctic sea ice extent is attributed to human induced climate change though. Researchers have found that natural variability accounts for about half of the sea ice decline observed so far; the other half coming from climate change. Therefore, a short period of stable Arctic sea ice extent trend is consistent with the models’ range of predictions. As National Snow and Ice Data Center (NSIDC) scientist Walt Meier pointed out in an article: “Natural variability has bigger effects at shorter timescales. It mainly plays a role over a time span of about 10 to 15 years. As the length of the observation period increases, natural variability has less effect, and the long-term forcing—greenhouse gas emissions—dominates. There is no escaping that we will see an Arctic with no summer sea ice this century if we continue to rapidly increase greenhouse gases in the atmosphere.”"
https://science.feedback.org/review/optimal-atmospheric-co2-dinosaurs-plants-harmful-humans-current-concentration-higher-homo-sapiens-ever-experienced/,Misleading,"Bright Insight, Jimmy Corsetti, 2024-02-04","High CO2 was fine for the dinosaurs and high CO2 benefits plants today in greenhouses, so more CO2 can’t be bad for humans",,"Flawed reasoning: The fact that elevated atmospheric-CO2 benefited the dinosaurs and benefits plants today does not mean it also benefits humans. In fact, there are potential human health risks from prolonged exposure to the optimal CO2 levels for dinosaurs and plants, in addition to the multiple negative environmental impacts for human society resulting from elevated CO2 and the enhanced greenhouse effect. Missing context: The optimal concentrations of CO2 for dinosaurs and plants would be far beyond the concentrations ever experienced by the human species naturally; they would dramatically change ecosystems. Even just the present level of CO2 in the atmosphere is already higher than it has been for millions of years, and Homo sapiens have only been around for 260-350 thousand years. The magnitude of change and the rate of change presents existential challenges for many species.","Elevated atmospheric-CO2 from human emissions enhances the greenhouse effect, which causes global warming and results in several other significant negative impacts on the ecosystems and natural processes on which humans depend. Plants and animals have different tolerances and responses to elevated CO2, and concentrations which are optimal for some species can be toxic for others. Human emissions have raised CO2 to levels never before experienced by our species, and not seen on Earth for millions of years.","Increasing carbon dioxide (CO2) is not bad for humans because it was much higher during the time of the dinosaurs and they were unaffected. High carbon dioxide also benefits plant growth, which is why CO2 is pumped into greenhouses to boost crop yields. Levels of CO2 are so low right now in comparison to the levels that were good for the dinosaurs and are good for plants, so an increase in CO2 can’t be bad for humans. CO2 is good for life and is not causing a climate crisis.","1 – Morris et al. (2018) The timescale of early land plant evolution. Proceedings of the National Academy of Sciences. 2 – Foster et al. (2017) Future climate forcing potentially without precedent in the last 420 million years. Nature Communications. 3 – Rae et al. (2021) Atmospheric CO2 over the past 66 million years from marine archives. Annual Review: of Earth and Planetary Sciences. 4 – Jacobson et al. (2019) Direct human health risks of increased atmospheric carbon dioxide. Nature Sustainability. 5 – Azuma et al. (2018) Effects of low-level inhalation exposure to carbon dioxide in indoor environments: A short review on human health and psychomotor performance. Environment International. 6 – Miller et al. (2005) The Phanerozoic record of global sea-level change. Science. 7 – IPCC (2019) Summary: for Policymakers. In: IPCC Special Report on the Ocean and Cryosphere in a Changing Climate 8 – Tierney et al. (2020) Past climates inform our future. Science. 9 – Zheng et al. (2018) The optimal CO2 concentrations for the growth of three perennial grass species. BMC Plant Biology. 10 – IPCC (2021) Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. 11 – Friedlingstein et al. (2023) Global carbon budget 2023. Earth System Science Data. 12 – Karnauskas et al. (2020) Fossil fuel combustion is driving indoor CO2 toward levels harmful to human cognition. GeoHealth. 13 – Lowe et al. (2018) Possible future impacts of elevated levels of atmospheric CO2 on human cognitive performance and on the design and operation of ventilation systems in buildings. Building Services Engineering Research and Technology. 14 – Diffenbaugh et al. (2013) Changes in ecologically critical terrestrial climate conditions. Science. 15 – IPCC (2023) Summary for Policymakers. In: Climate Change 2023: Synthesis Report. Contribution of Working Groups I, II and III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change","During Earth’s 4.5 billion year history, the atmosphere has undergone dramatic changes and only started to appear like it does today around 290 million years ago (mya). Today’s air is composed of several gasses with different concentrations, like nitrogen (78.08%), oxygen (20.95%), argon (0.93%), and carbon dioxide (0.04%). The air 600 mya, for example, had only about one-fifth of today’s oxygen level. Plants first appeared as far back as 500 mya[1]. Reptiles first appeared about 320 mya, and the dinosaurs only existed approximately from 243 mya until 66 mya. Mammals appeared about 225 million years ago, but anatomically modern humans, or homo sapiens, are only 260-350 thousand years old. Humans, dinosaurs, and plants all respire air, although plants do it very differently than mammals and reptiles. Considering these different evolutionary timelines under different atmospheric compositions, can we assume that animals, reptiles, and plants thrive breathing the same air? Is the optimal level of carbon dioxide for dinosaurs and plants also optimal, or at least feasible, for humans? Does all this mean anything for climate change? Youtuber Jimmy Corsetti, who’s channel Bright Insight has 1.61 million subscribers, suggested on X and Instagram that because dinosaurs and plants thrive under very high CO2, increasing in CO2 is good for life on Earth and not bad for humans. This means, according to Corsetti, “CO2 is Not causing a Climate Crisis”. Here we explore the reasons why this claim is misleading because it lacks context and uses flawed reasoning. Optimal carbon dioxide levels for dinosaurs and plants is toxic for humans over the long-term The atmospheric concentration of CO2 during the time of the dinosaurs was much higher than it is today, which currently stands at 422 parts per million (ppm). The article Corsetti screenshotted shows Dr. Paul Olsen’s response to the following question submitted by a reader: “How did plants and animals survive around 200 million years ago when the carbon dioxide concentration went up to 6,000 parts per million?”. Olsen, a geologist and paleontologist at Columbia Climate School’s Lamont-Doherty Earth Observatory, explains that the CO2 concentrations during the time of the dinosaurs (the Mesozoic Era) was in the 2000 to 4000 ppm range and that humans could potentially survive, but only with the help of technological innovations and not because of physiological ability. To be clear, the atmospheric concentration of CO2 during the time of the dinosaurs was never near 6000 ppm as Figure 1 shows[2], and it has never come close to that in the 66 million years since the dinosaurs went extinct[3]. Figure 1 – The rise and fall of atmospheric-CO2 (red trendline) over hundreds of millions of years (top x-axis), based on paleoclimatological reconstructions. Note the short timespan where Homo sapiens have existed, which has only featured low atmospheric-CO2 (right y-axis), especially compared to the Age of the Dinosaurs. Ice ages are indicated by blue shaded areas from the top x-axis. Based on reference [2], modified by Dr. Paul Olsen (source). According to Jacobson et al.’s (2019) recent synthesis of scientific literature from different fields exploring the impacts on CO2 air concentrations on humans, potential health risks can occur with exposure as low as 1000 ppm[4]. While concentrations above 5000 ppm are known to be harmful in both the short and long-term, research indicates that even concentrations below 5000 ppm “poses direct risks to human health”, including inflammation, reduced higher-level cognitive abilities, bone demineralization, kidney calcification, oxidative stress and endothelial dysfunction. Another literature review found physiological changes occur at CO2 exposures levels between 500 and 5000 ppm, effects on cognitive performance begin at 1000 ppm during short-term exposure, and respiratory symptoms are detected in children exposed to indoor CO2 concentrations higher than 1000 ppm[5]. Azuma et al. (2018) concluded that atmospheric CO2 concentration needs to be urgently suppressed to be able to efficiently control indoor concentrations. Most research on this topic is related to indoor environments, with humans under high exposure for limited time-frames corresponding to shift work in potentially hazardous workplace conditions. The Occupational Safety and Health Administration (United States Department of Labor) permissible exposure limit for CO2 is 5000 ppm over 8 hours. Concentrations above 40 000 ppm are considered immediately dangerous to life or health. There has been no research exploring prolonged human environmental exposure (weeks, months, years, lifespan) to elevated CO2 outdoors, especially for vulnerable demographics. Jacobson et al (2019) concluded that removing CO2 from the atmosphere will be necessary if emissions continue at current levels, based on their confirmation that “prolonged exposures as low as 1000 ppm CO2 affect human health and well-being”. In addition, during the Cretaceous period (145-66 mya) which ended when the dinosaurs went extinct, the average temperature was about 5-10°C higher than today and sea levels were 100 meters higher or more[6]. For comparison, the most extreme global warming future scenario (representative concentration pathway (RCP)) under consideration by the IPCC for the year 2100, called RCP8.5 or the “business as usual” scenario, implies a likely temperature increase of 3.2-5.4°C[7]. Figure 2 shows that the fossil-fuel intensive shared socio-economic pathway (SSP), called the SSP5-8.5 scenario, will lead to atmospheric-CO2 concentrations that match or even exceed Eocene or mid-Cretaceous levels[8]. It also illustrates just how unprecedented even a return to even just 1000 ppm CO2 would be, which has not been seen for tens of millions of years. Figure 2 – Comparing paleoclimates (past) with future climate scenarios side-by-side from the year 2020, including both global mean temperature (left y-axis, °C, only for the past) and global atmospheric-CO2 concentration (right y-axis, ppm, logarithmic scale, for the past and the future). Trendlines are smoothed to show long-term trends, and temperature colors are scaled related to pre-industrial levels. The small global maps on the right indicate different shared socio-economic pathway (SSP) scenarios (source). As for plants, Science Feedback has previously addressed flawed claims that because CO2 is used in greenhouses to promote plant growth, high CO2 in the atmosphere is good for the world’s plants and therefore not a concern for humans. Plants need more than just CO2 to photosynthesize and grow; they also need water, sunlight, and other plant nutrients like nitrogen and phosphorus. High CO2 in the atmosphere is directly linked to negative impacts on ecosystems through global warming which will constrain plant growth and limit any benefits from high CO2. For example, the increase in droughts in some regions or flooding in other regions are not beneficial for plants, regardless of high atmospheric CO2 (called the “CO2 fertilization effect”). Karin Kirk puts it simply with the title of her article for Yale Climate Connections: “More CO2 in the atmosphere hurts key plants and crops more than it helps”. But even if we ignore this (and all other climate related concerns of high CO2), and we focus just on maximizing plant growth as we do in greenhouses as referenced by Corsetti, the optimal CO2 levels for plants are still in conflict with human well-being. All plants respond differently to increased CO2, but they all generally follow a downward parabola (upside down “U”), increasing yield with increasing CO2 until reaching an optimal point (vertex) after which yield decreases with increasing CO2 (Figure 3, right). Different plants have different optimums, but many greenhouse recommendations reference ideal concentrations at or surpassing 1000 ppm, assuming no other limiting factors exist. For example, Figure 3 (left) shows how increasing CO2 concentrations helps three species of grasses grow, with their ideal concentrations for biomass yield at 915, 1178, and 1386 ppm[9]. Figure 3 – Left: The impact of elevated CO2 concentrations (x-axis) on above ground biomass (a), below ground biomass (b), and total biomass (c) of three species of perennial grasses as quantified in Zheng et al. (2018). Right: Generalized relationship between CO2 level and plant growth rate. Note that a CO2 concentration of 300 ppm was considered “Normal Air” at the time this illustration was first sketched by Roger H. Thayer (see here for an early version), which has been reproduced over the years despite the global average now being 422 ppm (e.g., like the figure above provided by the Oklahoma State University Extension). As mentioned above, these elevated levels of CO2 concentration in the atmosphere would be potentially harmful for humans when inhaled indefinitely without respite (every hour of every day), especially for vulnerable demographics. So not only does high CO2 raise new challenges for plant growth (such as drought and flooding) and ecosystem stability, the optimum CO2 level for plants is incompatible with human physiology over the long-term. The high CO2 enjoyed by dinosaurs and plants is just not relevant for human well-being, making Corsetti’s suggestions misleading. Because of human activities, carbon dioxide is now higher than our species have ever experienced CO2 is considered the most important greenhouse gas because it has such a long residence time in the atmosphere, it is by far the most abundant, and it contributes the most to global warming and climate change. The direct and indirect environmental impacts of high anthropogenic-CO2 emissions are not just related to temperature increases, but also other changes across different components of the Earth system. Aside from air temperature increase, climate change has been observed with the oceans getting warmer, ice sheets shrinking, glaciers retreating, snow cover decreasing, sea level rising, arctic sea ice decreasing, and extreme weather events increasing in frequency (see here for evidence provided by NASA). Relative to global concentrations in the year 1750, atmospheric CO2 has increased by more than 47% because of human activities[10]. As indicated in Figures 1 and 2, the current level of atmospheric-CO2 (422 ppm) is now higher than the human species has ever experienced. Air trapped in ancient ice cores has demonstrated that CO2 has not been this high for at least the past 800 000 thousand years (ice record limit). NOAA stated in 2022 that CO2 levels are now comparable to the Pliocene Climatic Optimum, between 4.1 and 4.5 million years ago. As a reminder, Homo sapiens have only been around for 260-350 thousand years. Rather than the steep reduction in CO2 emissions needed to meet climate goals and limit global warming, 2023 saw another slight increase compared to year before (+1.1%), increasing 1.5% since before the COVID-19 pandemic, and representing a 10-year plateau of sustained high emissions and no significant reductions[11]. Humans have emitted 40.7 gigatons of CO2 in 2022, with a similar amount estimated for 2023. Increasing anthropogenic CO2 emissions like this raises concerns for human cognition and well-being outside just like it does indoors[12]. Of course, not all regions of Earth have exactly the same CO2 concentration at all times, some can exceed others due to geographical factors. In dense urban areas, especially large cities in low-lying basins, CO2 can build up. And with CO2 concentration increasing by about 2.4 ppm in 2023 worldwide[11], geographically constrained urban areas with high populations like Mexico City and Athens could see local concentrations reaching harmful levels for humans by the end of the century[13]. Finally, claims that elevated CO2 concentrations are not bad for humans as Corsetti suggested in his post generally ignore one more critical aspect: the rate of change. The current rate of increase is estimated to be occurring 10 times faster than any other change of similar magnitude over the past 65 million years[14]. As this is much faster than plants, animals, and humans can evolve and adapt to (other than migration), and faster than ecosystems can sufficiently respond to, the risk of extinction is enormous in the coming decades (up to 29% of land plants and animals at risk of being wiped out with 3°C of warming; we are currently at 1.1°C of warming)[15]. CO2 by itself is not causing a climate crisis; elevated CO2 emissions from human activities are. Conclusion: The claim that because high CO2 was fine for the dinosaurs and high CO2 benefits plants today in greenhouses, high CO2 can’t be bad for humans is misleading. Firstly, the optimal carbon dioxide levels for dinosaurs and plants is, in fact, harmful for humans over the long-term. The age of the dinosaurs (the Mesozoic Era) had atmospheric-CO2 in the 2000 to 4000 ppm range, and plants typically grow best at 1000 ppm of CO2 or greater (like in greenhouses). Humans, on the other hand, can suffer mild health effects from CO2 as low as 1000 ppm even in the short-term, and the effects of permanent exposure to elevated CO2 levels are unknown. This is especially relevant for vulnerable populations, and anyone living in low-lying, densely populated urban areas. Humans as a species have never before experienced the high level of CO2 currently in the atmosphere, which is higher than it has been for as long as ice records can tell us (800 000 years). CO2 by itself is not causing a climate crisis; elevated CO2 emissions from human activities are."
https://science.feedback.org/review/study-calls-people-grow-their-own-food-years-come-despite-finding-higher-carbon-footprint-compared-conventional-agriculture/,Misleading,"Facebook, The Atlas Society, Social media users, 2024-01-26",Study and headline saying homegrown food is more carbon intensive than conventional agriculture is meant to discourage and stop people from growing their own food,,"Misrepresents source: New study which quantified a higher carbon footprint of urban agriculture compared to conventional agriculture does not discourage or call for people to stop growing their own food. On the contrary, the study proposed multiple solutions to reduce carbon emissions and calls for maintaining and supporting urban agriculture, including home gardens, as long-term components of sustainable cities.","Although low-tech urban agriculture is expected to be a central component of sustainable cities in the future due to its many social, ecological, and nutritional benefits, new research demonstrates it is not necessarily less carbon intensive than conventional agriculture as commonly assumed. Scientists in general not only argue for long-term maintenance of urban agriculture as a tool for sustainable development, they also find ways to reduce the carbon footprint of home and community gardens, such as reusing the same infrastructure year-over-year. There is no evidence of scientists calling for the restriction of urban agriculture, home gardens, and citizen rights to growing their own food to reduce carbon emissions.",New study and article headline saying homegrown food is worse for the climate than conventional agriculture is ridiculous propaganda meant to discourage and ultimately ban people from growing their own food. Growing your own food in your garden will soon be prohibited in the name of climate change because they say it is more carbon intensive than conventional agriculture.,"1 – Nicholls et al. (2020) The contribution of small-scale food production in urban areas to the sustainable development goals: A review and case study. Sustainability Science. 2 – Lee et al. (2015) Greenhouse gas emission reduction effect in the transportation sector by urban agriculture in Seoul, Korea. Landscape and Urban Planning. 3 – Azunre et al. (2019) A review of the role of urban agriculture in the sustainable city discourse. Cities. 4 – Appolloni et al. (2021) The global rise of urban rooftop agriculture: A review of worldwide cases. Journal of Cleaner Production. 5 – Goldstein et al. (2017) Contributions of local farming to urban sustainability in the Northeast United States. Environmental Science & Technology. 6 – Maureira et al. (2022) Evaluating tomato production in open-field and high-tech greenhouse systems. Journal of Cleaner Production. 7 – Ribeiro et al. (2023) Evidence on how urban gardens help citizens and cities to enhance sustainable development. Review: and bibliometric analysis. Landscape and Urban Planning. 8 – Hacking & Guthrie (2008) A framework for clarifying the meaning of Triple Bottom-Line, Integrated, and Sustainability Assessment. Environmental Impact Assessment Review. 9 – Ikeda et al. (2023) The Role of Urban Gardening in Global Cities: Three Case Studies in Berlin, Rome and Tokyo. In Sustainable Health Through Food, Nutrition, and Lifestyle. Springer Nature. 10 – Orsini & D’Ostuni (2022) The Important Roles of Urban Agriculture. Frontiers for Young Minds.","To meet global food challenges, such as increases in overall food demand alongside decreases in the natural resources needed for food production, urban agriculture is expected to play a critical role in the coming decades[1]. Because of the significant potential for transport carbon emissions reductions when food is grown close to the point of consumption[2], as opposed to in rural areas far away, there is the assumption that urban agriculture can be much less carbon intensive than conventional agriculture. As more scientific studies are performed, we gain more insight into urban agriculture’s full carbon footprint. Hawes et al. (2024) (“the Hawes study”) added more context to this topic by examining life cycle impacts of low-tech approaches in their new study published on 22 Jan. 2024. But what they found was unexpected: individual gardens are about five times more carbon intensive per serving of fruit or vegetables than conventional farming. The study was covered in an article in the Telegraph online, which started a wave of misrepresentation on social media. The Telegraph headline “Carbon footprint of homegrown food five times greater than those grown conventionally” was screenshotted and shared widely in multiple unique posts (such as this and this) alongside the general claim that the study implies urban agriculture is bad for the climate and, therefore, may be banned. One example from a Facebook group with 237 thousand followers has the caption: “Now will they come for your backyard veggie garden? #Reason #GlobalWarming”. Another example from a Facebook group with over one million followers asked: “Which country will be the first to declare home gardens a climate crime? This is absolute lunacy”. Joe Rogan (18.6 million Instagram followers) shared the Telegraph headline with the caption “Anyone that discourages people from growing their own food is not your friend” (over 410 thousand likes). As explained below, the claim that the study’s findings were meant to discourage and stop people from growing their own food misrepresents the original study. The claim is also unsupported within the context of the wider scientific community’s interest in promoting the multiple ecological and social benefits of urban agriculture, regardless of carbon related considerations[3-5]. These benefits were explicitly emphasized in the Hawes study, and again in their explainer article in The Conversation published on the same day, but they were not discussed in the Telegraph’s widely shared article. The Telegraph article also failed to mention that a quarter of home gardens studied outperformed conventional agriculture, which is clearly stated in the study’s publicly visible abstract. No statements against urban agriculture, home gardens, or citizen rights In the Hawes study, there are no statements nor calls against the use of urban agriculture or home gardens. There is also no indication whatsoever that people should not grow their own food. The carbon footprint of food produced using urban agriculture was found to be six times greater than conventional agriculture on average (see below for details). Even with their unexpected findings, the authors highlighted the situations where low-tech urban agriculture outperforms conventional agriculture from a carbon footprint perspective. They suggested best practices to keep low-tech urban farms, individual gardens and collective gardens as long-term fixtures in cities by making them more carbon-competitive. The Hawes study is emphatically not a call to discourage, limit, or criminalize people growing their own food. In an email with Science Feedback, lead and corresponding author Jason Hawes (School for Environment and Sustainability, University of Michigan) reiterated: “We did not call for a ban on urban farming and gardening…our team has more than a century of experience studying the many personal and community benefits that these urban food-growing sites produce…none of our recommendations involved banning the practice – in fact, we suggested that one key [best] practice would be to ensure long-term land tenure for urban agriculture sites.” In the study’s abstract, the authors clearly call for “maintaining [urban agriculture] sites for many years”. In the study’s conclusion, the authors stressed that because of urban agriculture’s many social, nutritional, and environmental benefits (explored below), it is likely to “have a key role to play in future sustainable cities”. There is no evidence that this study has been or will be used in any way, in policies or laws for example, to limit citizen rights to have home gardens as a new strategy to mitigate climate change. The claim that the study’s main finding, as headlined in the Telegraph, is meant as propaganda to discourage urban gardening and stop people from growing their own food is inaccurate. What did the study do, find, and propose? By partnering with individual gardeners, community garden volunteers and urban farm managers at 73 sites across five countries in North America and Europe, Hawes and colleagues tested the assumption that low-tech urban agriculture is less intensive than conventional agriculture. This assumption is mainly based on the fact that transportation emissions, which are very significant for conventional agriculture, are drastically and in some cases entirely reduced in urban agriculture. The study aimed to clarify previous uncertainties from earlier studies, and provide the first large-scale, comprehensive assessment of the full life cycle carbon footprint of different types of low-tech urban agriculture compared to conventional agriculture. Food product emissions were quantified from three types: urban farms (professionally managed, focused on food production), individual gardens (small plots managed by single gardeners) and collective gardens (communal spaces managed by groups of gardeners). For each country, the study included food produced using conventional agriculture both domestically and abroad, considering on-farm impacts, processing and transportation to the city. High-tech urban agriculture was not considered. The carbon footprint of food produced using urban agriculture on average (all three categories) was found to be six times greater than conventional agriculture (420 grams of carbon dioxide emissions equivalent (gCO2e) versus 70 gCO2e per serving), with the individual gardens category being about five times more carbon intensive (340 gCO2e, hence the Telegraph headline highlighting the term “homegrown food”). The main reason why urban agriculture was found to be more carbon intensive than conventional agriculture was the emissions associated with its infrastructure. This includes using raised beds, concrete walkways, small shelters like sheds, and so on, all of which add emissions that are not necessarily comparable to the wide-open fields of conventional farms which can produce food at-scale. In addition, only urban grown tomatoes and asparagus were less carbon intensive than conventionally grown versions among the crops considered. This is likely because conventional tomatoes are already very carbon intensive when grown (i.e., industrial greenhouses) and still need to be transported to the city, meaning urban grown versions are carbon-competitive[6]. Conventionally grown asparagus often requires air-freight importation and when this is factored in “the statistical difference between individual gardens and conventional agriculture vanishes”. Grouping all urban agriculture categories together, 17 of the 73 sites (23%) had less emissions than conventional agriculture, which helped the authors identify best practices to ensure the longevity and sustainability of urban farms, individual gardens and collective gardens in cities, contrary to the claims made on social media. They suggested that practitioners of urban agriculture and policy makers should: maximize the lifespan of farm infrastructure; promote urban waste streams as inputs, and, use farms as sites for education, leisure and community building. Based on the results and expertise of the authors, the Hawes study is in reality a call for people who grow their own food to explore how they can reduce their carbon footprint “by cultivating crops that are typically greenhouse-grown or air-freighted, maintaining [urban agriculture] sites for many years, and leveraging circularity (waste as inputs).” Scientists continue to research and call for more urban agriculture Urban agriculture, farming, and gardening refers to food production in urban areas, including animal husbandry, aquaculture, beekeeping, and horticulture. By enhancing vegetation cover in cities, which increases shade, evapotranspiration, and creates an urban cooling effect, urban agriculture is an internationally recognized option for climate change adaptation (e.g., featured since 2016 in the European Climate Adaptation Platform Climate-ADAPT). Hawes and colleagues are part of the wider scientific community investigating how to minimize the potential costs and maximize the already significant benefits of urban agriculture, especially low-tech approaches and home gardens. Senior researcher Dr. Johannes Langemeyer of the Integrated System Analysis of Urban Vegetation and Agriculture (URBAG) project provided Science Feedback with some insight into the wider context surrounding studies like the one by Hawes and colleagues, in relation to the unique functions of home gardens aside from food production. Based at the Institute of Environmental Science and Technology of Universitat Autònoma de Barcelona (ICTA – UAB), Dr. Langemeyer explained: “Commercial agriculture is primarily optimized for maximizing production yields. In contrast, urban gardening – distinct from urban agriculture – often does not prioritize food production as its primary goal, especially in regions like Europe, the US, and the UK. Urban gardening typically serves multifunctional purposes, such as fostering a connection to nature, providing educational opportunities, and facilitating leisure activities. Therefore, comparing CO2 emissions on the basis of production yield can be misleading, as the objectives of commercial agriculture and urban gardening are fundamentally different. A hypothetical reversal of this comparison might illustrate this point more clearly. For instance, if one were to compare commercial agriculture with urban gardening based on the leisure hours each provides, and possibly the CO2 emissions associated with these leisure hours, the contrast in objectives and outcomes would become more apparent. This perspective highlights the importance of considering the specific goals and functions of different agricultural practices when making such comparisons.” Scientists have been increasingly studying the role of different forms of urban agriculture, like urban community gardens, in driving sustainable development in cities (Fig. 1). There have been at least over 200 independent scientific studies exploring the different sustainable development aspects of urban gardens, with a drastic increase in recent years as scientists have recognized that “promoting urban gardens could be a relevant urban policy directed towards sustainable development”, as concluded by Ribeiro et al. (2023) following a comprehensive bibliometric analysis[7]. Figure 1. Visual overview of the Ribeiro et al. (2023) bibliometric analysis of the scientific literature on urban gardens as tools to promote sustainable development in cities, assessed using the triple-bottom-line framework (see reference [8]).Top: Publications meeting the analysis criteria according to the year of publication (x-axis), demonstrating growth in interest (number of publications indicated in the y-axis). Bottom: The cluster analysis of the publications selected with the most citations, based on the triple-bottom-line sustainable development pyramid. Urban farming can address 13 out of the 17 United Nations Sustainable Development Goals across economic, social and ecological vectors, as demonstrated by some of the outputs of the international GROOF (Greenhouses to reduce CO2 on Roofs) project. Although carbon emissions are a legitimate concern that must be quantified, just as Hawes and colleagues performed for low-tech approaches, urban gardens have been documented across different socio-cultural contexts to do more than just provide food. They also provide public spaces for citizens’ well-being, and serve as meeting places and as places of learning, especially in recent years during the COVID-19 global pandemic[9]. Scientists have even undertaken efforts to encourage the world’s youth to know about and participate in urban agriculture, for example with the article “The Important Roles of Urban Agriculture” published in the journal Frontiers for Young Minds[10]. Opinion articles with titles like “Urban gardening has taken root, and it’s time for cities to encourage new growth” by urban planning experts outside of traditional academia demonstrate the widespread support of urban agriculture as a permanent fixture in urban life, contrary to the claim on social media that studies like Hawes et al. (2024) imply experts want the opposite. The United Nations University even hosts a video series on the role of urban gardens in biodiversity conservation and sustainable development. But just like from the carbon footprint perspective, the social and community aspects of urban agriculture has both benefits and limitations (see here for an overview within the US context, including 40 references of studies by scientists exploring the critical value of urban agriculture). The growth in research interest in urban agriculture and the scientific debate surrounding potential risks and benefits were also outlined in a Global Sustainable Development Report brief in 2015. Overall, as far as we are aware at Science Feedback, there is no evidence of scientists making any efforts related to restricting urban agriculture, home gardens, and citizen rights to growing their own food by citing climate change related concerns. Conclusion: Although low-tech urban agriculture is expected to be a central component of sustainable cities in the future due to its many social, ecological, and nutritional benefits, Hawes and colleagues found it is not necessarily less carbon intensive than conventional agriculture as is commonly assumed. There are multiple ways to reduce the carbon footprint of different kinds of urban agriculture to make them more carbon-competitive with conventional agriculture, such as reusing the same infrastructure year-after-year. The claim that the study and article headline chosen by the Telegraph is meant to discourage and stop people from growing their own food has no support in reality. The study has been misrepresented on social media; there are no statements nor calls against the use of urban agriculture or home gardens within the study or anywhere else among the wider scientific community. On the contrary, Hawes and colleagues clearly call for “maintaining [urban agriculture] sites for many years”, and they concluded that urban agriculture will “have a key role to play in future sustainable cities”."
https://science.feedback.org/review/us-proposed-bills-hearings-dont-confirm-chemtrails-exist-not-geoengineering-strategy/,Inaccurate,"Facebook, YouTube, Social media users, 2024-01-12","US state governments are banning chemtrails, confirming secret government programs using chemtrails for various purposes that harm the public and the environment",,"Factually Inaccurate: No US state government has passed laws banning chemtrails, which remain unproven and not supported by any scientific evidence. US congressional documents have been misattributed and misinterpreted as admissions of chemtrail existence. Proposed bills, citizen petitions, and committee geoengineering hearings do not prove the existence or use of chemtrails.","Contrails are trails of condensing water vapor left in the wake of airplanes. They do not contain harmful chemicals as proposed by ""chemtrail"" conspiracy theories, which are not supported by any evidence. Although some politicians have proposed bills to ban chemtrails or related conspiratorial concepts, they are not evidence of their existence and no such bills have been passed. Chemtrails are increasingly conflated with solar geoengineering strategies, like stratospheric aerosol injection, but these strategies are real proposals currently being explored by scientists to limit anthropogenic global warming and have not been implemented at scale.","There are secret government programs using chemtrails for various purposes that harm the public and the environment. This is confirmed by New Hampshire and Texas state governments referencing and forbidding chemtrails, and a Tennessee government hearing on the development of geoengineering projects like stratospheric aerosol injection. These sources prove chemtrails are real, harmful, and distinct from contrails. Climate change mitigation is not the real reason behind geoengineering.","1 – Shearer et al. (2016) Quantifying expert consensus against the existence of a secret, large-scale atmospheric spraying program. Environmental Research Letters. 2 – Burns et al. (2016) What do people think when they think about solar geoengineering? A review of empirical social science literature, and prospects for future research. Earth’s Future. 3 – Tingley and Wagner (2017) Solar geoengineering and the chemtrails conspiracy on social media. Palgrave Communications.","There is no credible, scientific evidence that chemtrails exist and are distinct from contrails. Claims that chemtrails exist have been addressed multiple times previously on Science Feedback (e.g., here). Yet, on 12 Jan. 2024, social media user “OFF GRID with DOUG and STACY” (701 thousand Facebook followers, 1.19 million YouTube subscribers) posted a video to their accounts claiming multiple US state governments have confirmed the existence of chemtrails in the text of bills and committee hearings designed to protect citizens from their negative effects, asking the question: “So, if they don’t exist, if there’s no such thing, why are they trying to ban them?” This post, which specifically references the US state governments of New Hampshire, Texas, and Tennessee, has been viewed over 200 thousand times between YouTube and Facebook, receiving tens of thousands of likes and shares. Several other similar claims are also being widely shared on different online platforms by other accounts currently. This review explains why this claim is based on inappropriate sources and is factually inaccurate, broken down by state. Misrepresented, misattributed, and exaggerated sources New Hampshire claim On 19 Dec. 2023, a New Hampshire House Bill was introduced by Rep. Jason Gerhard [R] (main sponsor) and Rep. Kelley Potenza [R] (co-sponsor). The bill (HB1700) was to be known as ‘The Clean Atmosphere Preservation Act’ but was voted “Inexpedient to Legislate” as of 31 Jan. 2024. This means that the bill is considered killed. The post author inaccurately claims “New Hampshire is now actively trying to ban chemtrails over their state.” The bill text does not refer to the term “chemtrails”. Instead, the bill is a proposal for “AN ACT prohibiting the intentional release of polluting emissions, including cloud seeding, weather modification, excessive electromagnetic radio frequency, and microwave radiation and making penalties for violation of such prohibition.” Terms like cloud seeding and other strategies of geoengineering have been publicly and openly debated for decades and are still under debate by scientists, who are uncertain whether the risks are comparable to unmitigated global warming. Chemtrails, on the other hand, have never been scientifically verified and therefore do not have a universally accepted definition that can be used to objectively verify if proposed bills like HB1700 are intended to ban them. The Merriam-Webster dictionary defines chemtrails as “a long-lasting airplane contrail believed to be composed of harmful chemical or biological agents that are dispersed as part of a conspiracy (as to manipulate the environment or the population)”. Contrails are streaks of condensed water vapor created in the air by an airplane or rocket at high altitudes (the factors of their formation are described further in a previous Science Feedback claim review). Chemtrails are not chemtrails, despite photos and videos of contrails continuously used as evidence for chemtrails. Most importantly, HB1700 was simply a proposal for a new law. Legislators in the US, like Rep. Jason Gerhard [R], are generally free to propose bills on a wide range of topics, regardless of their scientific foundation. Citizens, interest groups, and others can suggest a bill idea directly to legislators, but formal bill proposals must be sponsored by a legislator and go through many steps (outlined here), including potentially undergoing major changes and amendments. It can take months to years before a bill is either accepted or rejected. A bill proposal text is not to be taken literally because it must first be debated and approved by the New Hampshire General Court. But in the video post, HB1700 is taken for fact, for example with the post author repeating the specific text “The general court finds…” without providing viewers crucial context that this language is only true if the bill becomes a law. The post author inaccurately claims that New Hampshire is trying to ban chemtrails despite the fact that HB1700 does not refer to chemtrails and is simply a proposal that was sponsored by 2 of the 424 New Hampshire legislators. The progress of the bill can be reviewed here. Texas claim While appearing to read from an internet article from The People’s Voice (formerly known as Your News Wire, one of the most prolific sources of fake news on Facebook), the post author states that: “Texas made history last year when state representatives looked into changing a law to ban dangerous atmospheric aerosol spraying without prior approval and testing of the chemicals being sprayed.” This is inaccurate. In reality, The People’s Voice article refers to an online petition to “…prohibit the continuation of aerosolized spraying” of substances and particulates which “…is extremely harmful to our health and our environment”. Chemtrails are not referenced anywhere in the petition text, but it further states that there is a covert military program to control weather whereby “weather modification is frequently used to justify the spraying” of things like “aluminum oxide and other toxic metal compounds”. A previous Science Feedback claim review explained that allegations of secret large-scale atmospheric programs using chemtrails lack any supporting evidence (i.e., proof) and foundation (i.e., hypothetical basis)[1]. There are no scientific studies nor any existing data confirming elevated global atmospheric, soil, sediment, or water concentrations of the various chemicals that chemtrails are claimed to spread. With thousands of signatures and comments and featuring a photo of contrails, the petition webpage states that it is an initiative from “concerned Texas citizens who demand our State Legislators pass legislation to protect our families, pets, crops, water and environment from any and all negative side effects of…spraying of our sky”. Regardless of the lack of any legitimate and scientifically verifiable supporting evidence, the post author exaggerates the following: “They’re literally admitting they’re allowing people, willy-nilly, to spray in the skies chemicals that have not even been tested for human consumption, or what they could do to the environment, or anything else.” After claiming chemtrails are real and anyone stating otherwise is “gaslighting” later in the video, the post author introduces another bill proposal, saying “Now here’s Texas HR 2977”. However, HR 2977 was a Congressional Bill from the 107th Congress of the US Government (not Texas), proposed in 2001 by Ohio Rep. Dennis Kucinich [D] as the “Space Preservation Act of 2001”. It was intended to “preserve the cooperative, peaceful uses of space for the benefit of all humankind by permanently prohibiting the basing of weapons in space.” Bill HR2977 never passed, but it did explicitly refer to “chemtrails” among various so-called exotic weapons such as extraterrestrial weapons. The post author goes on to claim “I like how Texas actually concluded that little video segment there with the radio waves, mood altering stuff, chemtrails, the aluminum, all these kinds of things going on, all the things the conspiracy people have been talking about for quite a while are right in your face.” Once again, legislators can propose bills on a wide range of topics, regardless of their scientific basis. Bill proposals do not, in and of themselves, prove the existence of all terms included in the text. Tennessee claim The post author also claims that the Tennessee government held a major hearing about geoengineering, alluding to chemtrails being a form of geoengineering (discussed further below). In reality, the document that is quoted comes from an official hearing (see here for full hearing text, see here for hearing video footage) on the subject of geoengineering in 2009/2010 during the 111th Congress of the US Government (not Tennessee), specifically for the Committee on Science and Technology of the House of Representatives. Geoengineering to mitigate negative impacts from climate change and slow global warming are typically grouped into two categories: actively removing carbon dioxide from the atmosphere with different strategies to reduce the greenhouse effect; and reflecting sunlight from the planet to reduce heat inputs. Chemtrails, as generally defined, are not related to the topics that were discussed in the hearing. Chemtrails were mentioned in passing as a joke by subcommittee chairman Hon. Brian Bard, with reference to the need to be transparent with the public on geoengineering strategies if they are ever used in the future. In 2009, the potential risks, challenges and opportunities of geoengineering strategies had become more mainstream, which is why it was presented to the Committee on Science and Technology on the national stage at this hearing. It received wide dissemination in the public at the time, and is still openly explored in the public sphere. Additional context on chemtrails misinformation and their conflation with solar geoengineering The People’s Voice was one of the main sources of the misinformation on social media related to the inaccurate claims posted by OFF GRID with DOUG and STACY in January 2024. Its 19 Jan. 2023 story on the Texas citizen petition was misleadingly titled “Texas Becomes First State To Potentially Outlaw Chemtrails”. Nearly one year later, 3 Jan. 2024, The People’s Voice published another article inaccurately titled “New Hampshire Becomes Second U.S. State To Ban Chemtrails”, misinforming its readers on the New Hampshire proposed bill HB1700. Both articles were written by Your News Wire co-founder Sean Adl-Tabatabai who has a record of influential climate misinformation articles and who also founded The People’s Voice. These articles preceded multiple social media accounts repeating similar inaccurate claims in addition to the ones addressed above. For example, in the days since the most recent article from The People’s Voice, an Instagram account released three video posts on chemtrails as toxic climate/geoengineering, with the third on 19 Jan. 2024 claiming there are now two US states that have outlawed “climate engineering” while filming contrails. A post from another Instagram account repeated inaccurate claims from The People’s Voice article on the New Hampshire proposed bill HB1700, and repeated the inaccuracy that the bill had been passed and chemtrails have been banned. This is certainly not the first time government documents, whether hearings, bill proposals, policy agendas, or scientific reports, have been misrepresented as proof of the chemtrail conspiracy. Social media posts in recent years inaccurately claimed the UN is creating climate change using geoengineering and chemtrails, and the chemtrails are a key tool used to control the weather, with climate change being only a cover-up. Last year, the Mexican government announced a ban on solar geoengineering after an American start-up tested atmospheric sulfur injections from balloons over Mexico without any notice or approval. However, this ban was misrepresented on social media as a ban on chemtrails, despite chemtrails being unrelated to the new Mexican law and unsupported by any scientific evidence. Inaccurate claims that a 2022 CNBC story was actually as an admission of a secret chemtrail program went viral on social media. The story was about a new five-year plan assessing the use of solar and other interventions to mitigate climate change coordinated by the White House Office of Science and Technology Policy and US federal agencies, as directed by Congress. One intervention to be researched is stratospheric aerosol injection. Professor David Keith, a solar geoengineering expert leading a research group dedicated to this topic, told the Associated Press by email that aerosol injection would not leave contrails like those left by planes. Chemtrails remain unproven, unverified, and undiscovered by science. A 2016 study which surveyed of some of the world’s top atmosphere experts, consisting of atmospheric chemists with expertise in condensation trails and geochemists working on atmospheric deposition of dust and pollution, virtually every single respondent did not believe there is any scientific evidence for a secret large-scale atmospheric program using chemtrails[1]. Even when assessing data that conspiracy theorists claim is proof of chemtrails, such as elevated concentrations of specific elements in soils, sediments, and water bodies in remote locations, the overwhelming majority of the respondents stated that there are simpler and better supported explanations. As widely covered in the media, scientists are exploring the risks, rewards, and potential impacts of geoengineering technologies to mitigate climate change, including cloud seeding, solar geoengineering and carbon capture, none of which involve chemtrails. Solar geoengineering covers various hypothetical technologies and strategies that are meant to reflect sunlight out of Earth’s atmosphere to limit ongoing anthropogenic global warming. Ideas proposed for high altitudes, some of which being actively researched but not implemented, include placing a large mirror in orbit, thinning cirrus clouds, or spraying aerosols in the stratosphere (i.e., stratospheric aerosol injection) (Fig. 1). Figure 1 – Six of the most commonly proposed solar geoengineering options. They have different approaches, shortcomings, costs, and feasibility, but they are all designed to reduce the amount of solar radiation in Earth’s atmosphere and therefore limit ongoing anthropogenic global warming (source). There is a general unfamiliarity among the public with solar geoengineering[2]. Adding to the confusion and misinformation online, inaccurate conflations between chemtrails and solar geoengineering are increasing on social media. Science Feedback has addressed this issue in a previous claim review, pointing to the lack of any evidence for chemtrails and lack of evidence that solar geoengineering is happening and having a catastrophic effect on the ecosystems and human health. Tingley & Wagner (2017) found that between 30-40% of the general US public and as much as 60% of social media discourse believes in chemtrail conspiracy theories which “renders rational conversations around solar geoengineering and its potential role in climate policy even more difficult”[3]. Nevertheless, solar geoengineering proposals have been and continue to be publicly evaluated by scientists and government organizations (see here for scientists’ comments on some of the most popular strategies), weighing the pros and cons of each before recommendations are presented to elected officials, just like when they were discussed in front of the US Congress in 2009. Conclusion: Various accounts on social media inaccurately claim that US state and federal proposed bills and congressional hearings confirm the existence or use of chemtrails, with some states even banning chemtrails. However, no state governments have passed laws banning chemtrails, and bill proposals and the texts from congressional hearings are not evidence for the existence of chemtrails. Chemtrails as entities distinct from contrails remain unproven, unverified, and undiscovered by science. Chemtrails are increasingly conflated with solar geoengineering strategies, like stratospheric aerosol injection, which are real proposals currently being explored by scientists to mitigate climate change and limit anthropogenic global warming, but which have not been implemented. UPDATE (1 February 2024): We updated this review to indicate the new status of New Hampshire bill HB1700, which has been updated to “Inexpedient to Legislate” as of 31 Jan. 2024. This means that the bill is considered killed."
https://science.feedback.org/review/evidence-greenhouse-gasses-cause-global-warming-denied-willie-soon-tucker-carlson-interview-mass-social-media-climate-misinformation/,Incorrect,"Tucker Carlson Network, Willie Soon, 2024-01-09","Carbon dioxide does not cause global warming, scientists are 90% sure it’s the Sun; The climate problems blamed on carbon dioxide (such as ocean acidification and negative impacts on polar bears) are not real",,"Incorrect: The hypothesis that the Sun is responsible for climate change is inconsistent with real-world observations. Scientific consensus based on overwhelming evidence shows that greenhouse gasses like carbon dioxide are the main cause of current global warming, beyond reasonable doubt. Inaccurate: Elevated atmospheric carbon dioxide causes the enhanced greenhouse effect which has multiple direct and indirect impacts on the hydrosphere and biosphere, including ocean acidification and the reduction of arctic sea ice, which affects polar bear populations. Flawed reasoning: The fact that Saturn’s moon Titan is much colder than Earth despite having more methane does not mean that methane does not cause global warming on Earth as a greenhouse gas. In fact, methane causes the greenhouse effect on Titan just as it does on Earth.","The causes of climate change and global warming are well-known among the international scientific community. Scientific consensus based on overwhelming evidence, beyond reasonable doubt, shows that anthropogenic greenhouse gas emissions are the main driver of current global warming, not the Sun. Elevated atmospheric carbon dioxide has multiple direct and indirect impacts on the hydrosphere and biosphere, including ocean acidification and arctic sea ice loss due to global warming which affects polar bears.","We don’t know what is causing climate change, but we are around 90% sure it’s the Sun. Methane is on Saturn’s moon Titan and it has no global warming; it is cold because it is far from the Sun. There’s also no consensus on the role of CO2. The climate problems of CO2 are artificial and made-up; it does not cause issues like ocean acidification or make any difference to polar bear populations.","1 – Lockwood (2008) Recent changes in solar outputs and the global mean surface temperature. III. Analysis of contributions to global mean air surface temperature rise. In Proceedings of the Royal Society of London A: Mathematical, Physical and Engineering Sciences. 2 – Santer et al. (2023) Exceptional stratospheric contribution to human fingerprints on atmospheric temperature. Proceedings of the National Academy of Sciences. 3 – Sloan et al. (2016) Cosmic rays, solar activity and the climate. Environmental Research Letters. 4 – IPCC (2021) Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. 5 – Friedlingstein et al. (2022) Global carbon budget 2022. Earth System Science Data Discussions. 6 – Gazeau et al. (2007) Impact of elevated CO2 on shellfish calcification. Geophysical Research Letters. 7 – Molnár et al. (2020) Fasting season length sets temporal limits for global polar bear persistence. Nature Climate Change. 8 – Stern et al. (2016) Sea-ice indicators of polar bear habitat. The Cryosphere. 9 – Bromaghin et al. (2015) Polar bear population dynamics in the southern Beaufort Sea during a period of sea ice decline. Ecological Applications. 10 – Lunn et al. (2016) Demography of an apex predator at the edge of its range: impacts of changing sea ice on polar bears in Hudson Bay. Ecological Applications. 11 – Hörst (2017). Titan’s atmosphere and climate. Journal of Geophysical Research: Planets. 12 – MacKenzie et al. (2021). Titan: Earth-like on the outside, ocean world on the inside. The Planetary Science Journal. 13 – Myers et al. (2021) Consensus revisited: quantifying scientific agreement on climate change and climate expertise among Earth scientists 10 years later. Environmental Research Letters 14 – Lynas et al. (2021) Greater than 99% consensus on human caused climate change in the peer-reviewed scientific literature. Environmental Research Letters 15 – IPCC (2023) Summary for Policymakers. In: Climate Change 2023: Synthesis Report. Contribution of Working Groups I, II and III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change","Review: Dr. Willie Soon, an astrophysicist and aerospace engineer who has received “much” of his research funding from the oil and gas industry, made multiple claims during an interview with Tucker Carlson denying the role of greenhouse gasses like carbon dioxide (CO2) and methane in driving global warming. The original video on the Tucker Carlson Youtube page from 9 Jan. 2024 has since been split into numerous snippets, shared, liked, and viewed millions of times across multiple social media platforms. The core of Soon’s claims are inconsistent with science, as we will demonstrate below for three main claims Soon makes within the first third of the interview. Greenhouse gasses drive recent global warming, not the Sun Soon: “We may not know exactly what is causing climate change, we suspect it’s the Sun. We have a lot of evidence to show that it’s probably the Sun. Very high percentage, you know like I would say 90% we are sure” (minute 12:47) The drivers of climate change and global warming are well-known among the international scientific community. There is a straightforward history spanning back to the mid-19th century of how scientists have reached the consensus on anthropogenic climate change, which is that CO2 and other greenhouse gasses like methane emitted by human activities are causing current global warming. Scientists have known for over a century that CO2, in particular, is a key greenhouse gas that is strengthening the greenhouse effect in the atmosphere. Like the other known infrared-absorbing greenhouse gasses, CO2 absorbs and re-emits heat and therefore maintains a higher temperature in the atmosphere than non-greenhouse gasses. Since the first experiments, like those of Eunice Newton Foote in 1856, countless more studies have tested and validated the warming effect of increased atmospheric-CO2. Solar irradiance (the amount of power per unit area of solar energy reaching the Earth in the form of electromagnetic radiation, measured in watts per meter squared, W m–2) and its influence on the climate are well-understood by scientists and the evidence shows clearly that solar variability cannot account for the recent warming[1]. The effect of rising rates of atmospheric greenhouse gasses, on the other hand, has been well established by decades of scientific research. The Sun’s activity has been monitored since the beginning of the 20th century, and although solar irradiance can have yearly fluctuations, there has not been a statistically significant increase in recent decades, as opposed to global temperatures (Fig. 1). Solar irradiance has decreased since the 1960’s while global temperatures have increased. The warming influence of CO2 has been much greater than that of the Sun over the past century. Figure 1 – Comparison of the global surface temperature changes (red) and the Sun’s energy that Earth receives (yellow) in watts per square meter since 1880. One can see that since the 1960s, the global temperature and solar activity have varied in opposite directions, which wouldn’t be the case if the Sun was responsible for global warming (source). Soon claims the Sun is causing global warming, which means it is causing the recent warming observed at the surface of the Earth (i.e., the troposphere). If this was true, we should be able to observe warming at every layer of the atmosphere, especially at the top which receives the most radiation. Solar radiation reaching the surface on a clear day is around 1000 W m–2, while at the top of the atmosphere it is 1361 W m–2. However, the upper layers of the atmosphere (i.e., the stratosphere) have not increased in temperature in tandem with the surface layer. The temperature in the lower stratosphere (high altitude) has actually fallen while the temperature of the lower troposphere (low altitude) has risen, one of the main “human fingerprints on atmospheric temperature”[2]. This observation is consistent with the enhanced greenhouse effect, where heat-trapping gasses like CO2 in the troposphere cause temperature to increase. This observation is inconsistent with Soon’s claim. Estimates of the potential contribution of solar radiation to recent global warming further contradict Soon’s claim. At the high end, a 2016 study concluded that “the contribution of changing solar activity either through cosmic rays or otherwise cannot have contributed more than 10% of the global warming seen in the twentieth century”[3]. The IPCC has compiled robust estimates of all of the contributors to observed global warming, concluding that solar activity was a virtually non-existent factor in comparison to anthropogenic greenhouse gasses (Fig. 2). When comparing the effective radiative forcing (ERF, aslo measured in units of watts per meter squared (W m–2)) of global warming contributors since 1750, CO2 has an ERF of 2.16 W m–2, and methane is at 0.54 W m–2. Because these values are positive, they represent energy added to the Earth system, unlike the insignificant ERF for solar (indistinguishable from zero). Figure 2 – Top: The contributions of different drivers to global warming from the present time period (2010-2019) relative to the time period of 1850-1900 (source). The estimates of warming (red) and cooling (blue) from radiative forcing studies (panel (c)) are based on both direct emissions into the atmosphere and their effect, if any, on other climate drivers. Bottom: Change in effective radiative forcing from 1750 to 2019 by greenhouse gasses, ozone, stratospheric water vapor, surface albedo, contrails and aviation-induced cirrus, aerosols, and solar. The anthropogenic total category represents the combined positive and negative effects of human activities (everything except solar). The solid bars represent best estimates with very likely (5–95%) ranges represented by the error bars (source). Multiple direct and indirect environmental impacts of elevated CO2 in the atmosphere Soon: “What we know now is CO2 ain’t gonna cause nothing. It’s not gonna change much of the climatic system…it won’t make any difference with the polar bear population…it won’t even cause what they call ocean acidification” (minute 8:39) CO2 is considered the most important greenhouse gas because it has such a long residence time in the atmosphere, it is by far the most abundant, and it contributes the most to global warming and climate change (Fig. 2). Relative to global concentrations in 1750, atmospheric CO2 has increased by 47%[4]. Methane, which breaks down into CO2 after around a decade in the atmosphere, has increased by 156%. Through the enhanced greenhouse effect, human emissions of these gasses have resulted in an increase in average global temperature of more than 1°C since record keeping began in the second half of the 19th century. As temperature is pivotal to Earth’s climate system, Soon’s general claim that CO2 “ain’t gonna cause nothing. It’s not gonna change much of the climatic system” is at odds with reality. The direct and indirect environmental impacts of high anthropogenic-CO2 emissions are not just related to temperature increases, but also other changes across different components of the Earth system. Aside from air temperature warming, climate change has been observed with the oceans getting warmer, ice sheets shrinking, glaciers retreating, snow cover decreasing, sea level rising, arctic sea ice decreasing, and extreme weather events increasing in frequency (see here for evidence provided by NASA). Soon’s specific claims that CO2 does not make any difference with the polar bear populations nor cause ocean acidification are inaccurate and explored in detail in Box 1. Box 1. The impacts of CO2on polar bears and ocean acidification. Contrary to what Soon claims, CO2is directly linked toocean acidification. Theocean has absorbed between 20-30%of total anthropogenic CO2emissions in recent decades[5]. The excess carbon that is absorbed makes the oceans more acidic because when CO2dissolves in seawater, it forms carbonic acid, which lowers the pH of the ocean. Global surface ocean waters have increased in acidity by about 30% (because of a pH drop of 0.1) since the beginning of the Industrial Revolution, matching increases in atmospheric-CO2from human emissions (Fig. 3). Ocean acidification also causes a decline in carbonate ion concentrations and the calcium carbonate saturation state. When this lowers, carbonate minerals will dissolve, which can have implications for organisms with exposed calcium carbonate shells and skeletons, from corals to oysters, clams, and mussels. It has already been shown from experiments that the structure and function of marine species, particularly organisms with calcium carbonate shells or skeletons, are affected by ocean acidification[6]. Figure 3 –Recent trends in surface (< 50 m) ocean carbonate chemistry over the period 1988–2015 at the Hawaii Ocean Time-series (HOT) Program in the North Pacific. The upper panel shows the similar increase in CO2(CO2, as concentration in air (ppm)) in the atmosphere (red points) and surface ocean (blue points). The bottom panel shows a decline in seawater pH (light blue points, primary y-axis) and carbonate ion (CO32−) concentration (green points, secondary y-axis) (source). By driving global warming and reducing arctic sea ice extent, it is also well established that global warming has and will continue to negatively impact polar bear populations. A 2020 study estimated that, “with high greenhouse gas emissions, steeply declining reproduction and survival will jeopardize the persistence of all but a few high-Arctic subpopulations [of polar bears] by 2100”[7]. Because polar bears depend on sea ice for hunting, and because their main prey seals also depend on sea ice for breeding and making dens, arctic sea ice loss is making it more difficult for polar bears to hunt[8]. Studies correlating local losses in sea ice habitat with polar bear populations found that some subpopulations have already been negatively affected[9-10]. Loss of sea ice is occurring in almost all polar bear subpopulations, with arctic sea ice extent trending downwards since reliable satellite record keeping began in 1979 (Fig. 4). The downward linear trend in Arctic sea ice extent for December over the over four decades of satellite records is 43 400 square kilometers per year, or 3.4 percent per decade relative to the 1981 to 2010 average. Based on the linear trend, December has lost 1.97 million square kilometers of ice since 1979, equivalent to three times the size of Texas. Leading polar bear population experts Dr. Andrew Derocher and Dr. Ian Stirling told Science Feedback in a previous claim review that “Current [polar bear] declines are due to climate change associated loss of sea ice”, and “Several [polar bear] populations…declined significantly as a direct result of climate warming causing steady loss of sea ice”, respectively. Figure 4 –Monthly December ice extent shows a decline of 3.4 percent per decade over the period from 1979 to present day (source). Titan is climatically distinct from Earth and yet methane still causes the greenhouse effect on both Soon: “Titan…it’s very cold by the way, so it’s minus 290 degrees Fahrenheit. Hint, hint, hint, where is the global warming there, right, if it’s full of methane?…because it’s far away from the Sun that’s what it is.” (minute 2:33) Titan is much colder than Earth because it is far from the Sun, but Soon uses flawed reasoning to claim this means methane does not cause global warming (on Titan or on Earth). Dr. Sarah Hörst, Associate Professor at John Hopkins University and one of the world’s leading experts on Titan’s atmosphere and climate[11], explained to Science Feedback that “Titan receives substantially less Sunlight than the Earth so it should be about 82 Kelvin (-191.15 °C) but the greenhouse effect provided by methane results in a surface temperature that is about 12 K warmer”. Titan orbits Saturn, which is 1.4 billion kilometers away from the Sun on average, compared to Earth’s average distance of 150 million kilometers. Titan’s average temperature is around -179 °C (-290 °F), compared to Earth’s at around +15°C. So, even though Titan is still very cold (-179°C) because it is so far from the Sun, it would be even colder (-191 °C) without methane causing the greenhouse effect like it does on Earth. Titan receives approximately 1% of the solar radiation that Earth receives. Furthermore, of the solar radiation reaching the top of Titan’s atmosphere, only 10% reaches the surface (compared to 57% for Earth). Titan’s distinct atmosphere to Earth actually features both a greenhouse effect (provided by methane and collision-induced absorption) and an anti-greenhouse effect (from the stratospheric haze layer). For comparison, an Earth without methane and all the other greenhouse gasses causing the greenhouse effect, would be around -33°C colder. There are other reasons why Soon’s comparison of Earth and Titan to deny methane’s role in the greenhouse effect is flawed. At Earth’s current temperature, the atmosphere is able to hold on average 0.4% water vapor ranging from 4% in the humid tropics to nearly 0% in the polar regions. Water vapor, a known greenhouse gas explored in a previous Science Feedback claim review, is responsible for about half of the natural greenhouse gas effect keeping Earth warm. Titan, on the other hand, has virtually no water vapor anywhere because it is so cold and it has no liquid water. Overall, Titan has a completely different atmospheric composition, pressure, and gravity than Earth. Both Titan and Earth have a stratified atmosphere with a troposphere, stratosphere, mesosphere, and thermosphere, but Titan’s is much more extended because of its lower surface gravity (reaching heights of 15–50 km compared to Earth’s 5–8 km)[12]. Although Earth and Saturn’s moon Titan are the only two astronomical bodies with significant atmospheres and surface seas with stable liquids in the solar system, Titan’s climate cannot be directly compared to Earth’s. Titan’s atmosphere is mostly molecular nitrogen (about 95%) and methane (about 5%), compared to Earth’s 78% and 0.00018%, respectively. There is no widely accepted answer for how so much methane appeared on Titan, but there is no mystery that hydrocarbons can exist without originating from organic lifeforms like fossil fuels from plants and animals. Methane exists off Earth as a gas, liquid, or as ice. It is found on Neptune, Uranus, and there’s so much on Titan that it rains methane and there are lakes and rivers of liquid methane (and ethane). It is one of the most abundant types of ice detected outside of our solar system too, and scientists have even managed to create methane in a laboratory under space-like conditions. Additional context As we have shown above, Soon made multiple incorrect claims about the science of how greenhouse gasses like CO2 and methane are driving global warming. In the video, Soon also claimed the scientific evidence for global warming driven by CO2 is “all artificial” and dreamed up by the “tyranny of the few”. First, as we have shown, the science of climate change is actually built on real evidence that has been studied and compiled by tens of thousands of scientists over decades. Second, climate contrarians like Soon are, in fact, the extreme minority who have a disproportionately large influence over public opinion. Nearly all scientists agree greenhouse gas emissions are the cause of global warming. Among scientists with the most climate-related expertise, the consensus reaches 100%[13]. A recent peer-reviewed scientific study analyzing thousands of other peer-reviewed scientific studies found that 99% of the scientific literature confirms human greenhouse gas emissions cause global warming[14]. In the most recent IPCC report (AR6), the very first text line (line A.1.) of the “Summary: for Policymakers” directly contradicts Soon by stating “Human activities, principally through emissions of greenhouse gasses, have unequivocally caused global warming”[15]. The report confirms there has been 1.1°C of global warming since the period 1850-1900 and it explicitly identifies CO2 from human emissions as the leading cause (Fig. 2). As an indication of the scientific robustness of AR6, just the contribution from Working Group 1 alone was written by 234 of the world’s leading climate scientists coming from 66 countries. It included nearly 4 000 pages of research based on more than 14 000 scientific papers as supporting references and was critiqued and revised by over 1 500 expert reviewers. Incorrect and inaccurate claims like those made by Dr. Willie Soon in his interview with Tucker Carlson reach millions of people, amplified across social media platforms; they become super-spreaders of climate misinformation."
https://science.feedback.org/review/eu-not-passing-law-seize-scrap-cars-under-climate-agenda-contrary-peter-sweden-claim/,Inaccurate,"Twitter/X, Peter Imanuelsen (aka Peter Sweden), 2023-11-27",The EU could SEIZE and SCRAP your old car if it doesn't meet their criteria as part of their climate agenda.,,"Inaccurate: The EU Commission’s proposal does not mandate the seizure and scrapping of vehicles merely for failing to meet specific environmental criteria. Instead, it outlines how to assess and recycle vehicles that are neither economically repairable nor roadworthy, aiming to minimize environmental harm.  Inaccurate: Retaining an old combustion engine car is less beneficial for the climate than replacing it with an electric vehicle (EV), which offsets the initial emissions in a few years (driving ~40,000 km), particularly when the EV is lightweight and equipped with a smaller battery.","The EU Commission’s proposal focuses on regulatory measures aimed at manufacturers and the automotive industry; it doesn’t target car owners or consumers. Increasing the circularity of car parts and materials is expected to reduce the need for production and shipping of new materials, thereby lowering greenhouse gas emissions associated with manufacturing and transport.",The EU could SEIZE and SCRAP your old car if it doesn't meet their criteria as part of their climate agenda. Repairing an already existing car with spare parts is by far the best thing to do if you care about carbon emissions.,1 – IPCC (2022) Chapter 10: Transport. In: Climate Change 2022: Mitigation of Climate Change. Contribution of Working Group III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change,"In July 2023, the European Commission introduced a regulation proposal for end-of-life vehicles (ELV) to enhance vehicle life-cycle circularity in the European Union (EU). This initiative aims to ensure that vehicles are used to their fullest potential and that their components are recycled or repurposed at the end of their lifecycle. Following its announcement, numerous claims emerged on social media suggesting that the regulation would allow the EU to infringe on personal freedoms and threaten car ownership under the alleged guise of climate change and environmental concerns. The new end of life vehicles regulation targets the automotive industry, not consumers One such viral post was published by Peter Imanuelsen, also known as “Peter Sweden”, who has regularly shared climate change misinformation according to Climate Action Against Disinformation. Imanuelsen claimed that the EU could “SEIZE and SCRAP your old car if it doesn’t meet their criteria as part of their climate agenda.” His post further claimed that the state would dictate “how long you will be allowed to own your car”, suggesting there would be mandatory scrapping of vehicles that miss their regular EU checkup for two years or if the cost of repairing a car exceeds its market value. In reality, the EU Commission’s proposal does not mandate the seizure and scrapping of vehicles simply for not meeting certain environmental criteria. Instead, it provides guidelines for assessing vehicles that are neither economically repairable nor roadworthy, without stipulating specific consequences. In accordance with this, Annex 1 of the ELV proposal specifies that a vehicle is considered economically irreparable if its market value is lower than the cost of the necessary repairs required to meet road worthiness standards in the Member State where it is registered. This clause relates to evaluating the economic viability of repairing a vehicle; it does not enforce the seizure and scrapping of vehicles based solely on their condition. Furthermore, the EU Commission’s proposal does not specifically target car owners or consumers. The focus is on regulatory measures aimed at manufacturers and the automotive industry. In fact, the proposal is designed to promote new industrial practices in manufacturing and disposal, relevant only to the industrial sector. Thus, there is no evidence in the regulation’s terms that private cars could be seized and scrapped, contrary to Imanuelsen’s claim. Figure 1 – Extract detailing the proposal’s objectives, in the terms of the EU Commission’s proposal on circularity requirements for vehicle design and on management of end-of-life vehicles (source). Another document that reacted to the proposal is an online petition against it written by a Swedish bikers’ Magazine, which garnered over 12,000 signatures. The petition claimed that the proposal “concerns the purchase, sale, right to ownership of vehicles, parts and components, repair, renovation, restoration, preservation, and modification.” However, these claims are false, as the proposal does not introduce changes to the private rights related to car modifications. Indeed, the proposal focuses on transforming design and production industry requirements to increase both the quantity and quality of materials that are reused, remanufactured, and recycled (see Figure 1). The regulation’s potential impacts are openly available in an Impact Assessment Report, which is based on feedback from stakeholders. Would the regulation reduce carbon dioxide emissions? An overarching claim repeated several times in Imanuelsen’s post is that reducing carbon dioxide (CO2) emissions is merely a pretext for this proposal “to take away your freedom and control your life”. This new regulation is actually very likely to result in reducing carbon dioxide emissions as intended. The increased circularity of car parts and materials will reduce the need for production and shipping of new materials, thereby lowering greenhouse gas emissions associated with manufacturing and transport. This type of circular economy policy is indeed recognized by scientists as an “effective approach to mitigate industrial greenhouse gases emissions” in the latest IPCC assessment’s summary to policy-makers. Imanuelsen’s claim overlooks the very significant role of road vehicles in contributing to global greenhouse gas emissions. In 2019, direct greenhouse gas emissions from the transport sector accounted for 23% of global energy-related CO2 emissions, according to the IPCC’s latest assessment1. Most importantly, about 70% of direct transport emissions came from road vehicles (see category “Road” in Figure 2). Figure 2 – Evolution of the transport sector’s global greenhouse gases (GHG) emissions by transportation category from 1990 to 2019. Emissions are measured in gigatons, or billions of tons, of carbon dioxide equivalents (CO2-eq). This unit standardizes the climate effects of various greenhouse gases by equating their warming potential to that of carbon dioxide (source). While most CO2 emissions occur when a car is being driven, reducing emissions in the manufacturing phase still represents a significant opportunity, given the scale of the transport sector’s greenhouse gas emissions. According to the German Environment Agency, the manufacturing phase of an internal combustion vehicle, in case of a lifetime mileage of 168,000 km, has a share of 15% of the overall CO2 emissions (64% for the use-phase, 17% for fuel production and 4% for disposal and maintenance). The EU Commission has estimated that the proposed regulation would lead to an annual reduction of 12.3 million tons of CO2-equivalent in 2035. To put it into perspective, it can be compared to avoiding about 24 million flights from Paris to Helsinki a year, which emit about 0,5 tons of CO2-equivalent per passenger in Premium Economy class according to myclimate’s flight emissions calculator. Keeping an older car is not more beneficial for the climate Imanuelsen also claims that “repairing an already existing car with spare parts is by far the best thing to do if you care about carbon emissions”. However, replacing an old, inefficient vehicle with an electric vehicle (EV) does lead to a reduction in carbon dioxide emission. Although there is a bump in CO2 emissions during the production of an EV and its battery, the EV begins to offset these emissions after being driven for approximately 20,000 to 32,000 miles in the UK (equivalent to 32,000 to 51,000 kilometers), as illustrated in the chart below, according to a Carbon Brief analysis. Figure 3 – Lifecycle tonnes of CO2 (y-axis) per thousand miles of driving in the UK (x-axis) for an old pre-2015 petrol Ford Focus (grey trendline), old pre-2000 petrol Mercedes (black trendline), a new Tesla Model Y (red trendline) or new Nissan Leaf (peach trendline). Purchasing a new EV implies adding new CO2 emissions during its production and during the production of its battery (emissions accrued before the first mile driven, trendlines left of 0 on x-axis), but the lower emissions involved in the operation of an EV mean that these initial emissions are offset within a short period when compared to the continued operation of an old vehicle. After this crossover point (where trend lines cross in the gray shaded area), changing to and operating a new EV results in less total emissions than retaining an “old banger” (source). This analysis shows that a typical UK driver replacing an old vehicle, colloquially known as “bangers”, with a new electric vehicle (EV) will offset the initial carbon emissions from the EV purchase in about four years. The precise period for this carbon offset is dependent on several factors, including the fuel efficiency of the replaced car, the annual mileage of the driver, and the battery size of the new EV. Overall, retaining an old combustion engine car is not more beneficial for the climate compared to replacing it with an electric vehicle (EV), particularly when the EV is lightweight and equipped with a smaller battery. The regulation is expected to undergo several stages before it has a chance of being fully implemented. During this process, the proposal may be amended and will be subject to scrutiny by the European Parliament and the Member States. According to the proposal’s terms, it is acknowledged that implementation could take up to 8 years."
https://science.feedback.org/review/contrary-widespread-misrepresentation-new-study-finds-extremely-minimal-impact-human-breathing-climate/,Misleading,"Daily Mail, Jonathan Chadwick, 2023-12-13",Scientists say human breathing is fueling global warming,,"Misrepresents source: A new study found that human breathing in the UK contributes only 0.0539 of the UK’s 417 megatons of greenhouse gas emissions. The study did not show human breathing is significantly fueling global warming or bad for the environment. In reality, the authors said the contributions of human breathing pales in comparison to fossil fuel burning and other major sources of emissions.  Factually inaccurate: The Daily Mail’s claim that the gasses humans exhale contribute to 0.1% of the UK's greenhouse gas emissions is approximately eight times greater than the value the authors of the study estimated, which was 0.013%. In comparison, we have robust data quantifying the actual factors that fuel global warming, such as emissions from energy, transport, and land use.","Human breathing has been found to contribute around one hundredth of one percent of the total greenhouse gas emissions in the UK. Scientists do not claim we are fueling global warming by breathing. The human activities that are, such as greenhouse gas emissions from energy, transport, and land use, are well-known and must be reduced to mitigate the negative effects of climate change.","New study finds the gasses in air exhaled from human lungs are fueling global warming, contributing 0.1% of greenhouse gasses in the UK. Now scientists say breathing is bad for the environment.","1 – IPCC (2023) Summary for Policymakers. In: Climate Change 2023: Synthesis Report. Contribution of Working Groups I, II and III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change 2 – Polag & Keppler (2019) Global methane emissions from the human body: Past, present and future. Atmospheric Environment 3 – Mitsui et al. (1997) Effect of aging on the concentrations of nitrous oxide in exhaled air. Science of the Total Environment 4 – Van Der Geest et al. (2021) Slow-onset events: a review of the evidence from the IPCC Special Reports on Land, Oceans and Cryosphere. Current Opinion in Environmental Sustainability 5 – Wang et al. (1985). Potential climatic effects of perturbations other than carbon dioxide. In: Projecting the Climatic Effects of Increasing Carbon Dioxide. United States Department of Energy.","A new scientific study published on 13 Dec. 2023 quantified greenhouse gasses (GHG) emissions from human breathing in the UK and compared the results with other, more well-known known sources of emissions. Dawson et al (2023) found that only 0.05% and 0.1% of the UK’s methane and nitrous oxide emissions, respectively, can be attributed to people breathing. Overall, breathing is estimated to contribute 0.013% of GHG emissions in the UK. Despite these small percentages, over the next few days and weeks of this study being published, far-reaching online media sources (tabloids) and influential social media accounts misled the public by misrepresenting the study. Among the various headlines reaching millions of readers (a sample is listed further below), the Editorial Board of the New York Post published a piece about the study on 21 Dec. 2023 entitled “Climate fanatics now target BREATHING — proving how much they hate humanity”. Yet, on 13 Dec. 2023, the senior study authors stated explicitly “If you’re looking to reduce your climate impact, don’t hold your breath.” Multiple tabloids, websites and social media posts used the study to claim, whether sincerely or disingenuously, that breathing is causing and fueling global warming. Whatever the intended angle, these claims grossly misrepresent the study which estimated that humans breathing contribute roughly 1.3 of every 10 000 units of greenhouse gasses (0.013%). In particular, the Daily Mail (MailOnline) headline “​​Now scientists say BREATHING is bad for the environment: Gases we exhale contribute to 0.1% of the UK’s greenhouse gas emission” is inaccurate in its entirety. The study and its authors (Dawson and colleagues) never said or implied this, and this percentage value that Daily Mail presented their readers, who then shared it further online, is eight times greater than what the study actually found. The study’s corresponding author, Dr. Nicholas Cowan of the UK Centre for Ecology & Hydrology, has told Science Feedback that headlines like these are “a misinterpretation of what our study says and its message”. He adds: “The effect of human breathing would have extremely minimal impact on climate change – the overwhelming issue that should be the focus of efforts to mitigate global warming is the fossil fuels we burn, which our study made clear.” This claim review will put human breathing as a GHG source in context and outline more precisely what the authors found in comparison to the misleading and inaccurate viral claims which have ensued. Human breathing is not significantly fueling global warming There has been an increase in average global temperature of more than 1°C since record keeping began in the second half of the 19th century. Humans have caused all of the observed contemporary global warming. The main factors fueling global warming are clear; they all relate to increasing greenhouse gas emissions which results in the enhanced greenhouse effect. Roughly 79% of GHG emissions are linked to the energy, industry, transport, and building sectors, with the rest coming from the “agriculture, forestry and other land use” category[1]. An enhanced greenhouse effect means the atmosphere can maintain higher temperatures than before the GHG increase. The main GHGs which fuel global warming and which humans are responsible for are carbon dioxide, nitrous oxide, methane, and chlorofluorocarbons. Human activities like burning fossil fuels (for energy, transport, industry, etc.), cutting down forests, using intensive agricultural practices (especially involving nitrogen fertilizers and ruminant livestock), and using products that involve fluorinated gasses continue to raise GHG levels into unknown territories. Relative to 1750 levels, current atmospheric carbon dioxide has increased by 47% and methane by 156%, far exceeding the scale of natural changes over at least the past 800 000 years between glacial and interglacial periods[1]. Nitrous oxide has also increased by 23% since 1750. Carbon dioxide is considered the most important GHG because it has a long residence time, it is by far the most abundant, and it contributes the most to global warming (Fig. 1). Carbon dioxide causes about two-thirds of the final warming observed; it fuels global warming. Human breathing does not add carbon dioxide to the atmosphere. Figure 1 – Top: The contributions of different drivers to global warming from the present time period (2010-2019) relative to the time period of 1850-1900. The estimates of warming (red) and cooling (blue) from radiative forcing studies are based on both direct emissions into the atmosphere and their effect, if any, on other climate drivers. Y-axis indicates change in temperature in degrees Celsius (source). Bottom: Radiative forcing caused by major long-lived greenhouse gasses from 1979-2019 based on the change in concentration of these gasses in the Earth’s atmosphere since 1750. Radiative forcing is calculated in watts per square meter, which represents the size of the energy imbalance in the atmosphere. On the right side of the graph, radiative forcing has been converted to the Annual Greenhouse Gas Index (set to a value of 1.0 for 1990), which is a measure of the capacity of Earth’s atmosphere to trap heat as a result of the presence of long-lived greenhouse gasses (source). During breathing, human lungs oxygenate blood with atmospheric oxygen, in exchange for carbon dioxide which is cleared out from the lungs through exhalations (called gas exchange). However, the carbon dioxide we exhale is not relevant for global warming because it comes from the food we eat, which was produced using carbon dioxide that was already in the atmosphere. The amount of carbon we breathe out balances with the carbon we consume from plants and animals, with a little left to build and maintain our bodies. Human breathing adds virtually inconsequential amounts of GHGs The datasets we have for the big GHG emission sources, like those coming from land use or the energy and transport sectors, are robust because of their significance as drivers of global warming. But less important GHG sources receive less scientific attention. For example, we do not have much data on how much methane and nitrous oxide we exhale alongside carbon dioxide. The methane and nitrous oxide we exhale is newly added to the atmosphere, unlike carbon dioxide. Methanogenic flora in the human gut produce methane and denitrifying bacteria in the gut and oral cavity produce nitrous oxide. Previous studies estimate breathing contributes approximately 0.11% of methane and 0.16% of nitrous oxideemissions globally[2,3]. Although we already know emissions of these GHGs from breathing are very small, we do not have robust data on the exact quantities we exhale and what factors control them (e.g., our diet, age, gender, etc.). The new study by Dawson and colleagues was conducted to address this research gap and provide more data to compare. Of the 328 breath samples analyzed, they found 31% of people exhaled methane and all emitted nitrous oxide. Extrapolating their results to the full UK population of 68.2 million, they estimated 1.04 gigagrams (Gg) of methane and 0.069 Gg of nitrous oxide are exhaled annually, amounting to 53.9 Gg of CO2e (carbon dioxide equivalent units) in emissions. In relation to the total emissions of the UK, human breathing is estimated to account for 0.05% of the methane (2051 Gg of methane emitted in 2021) and 0.1% of nitrous oxide (72 Gg of nitrous oxideemitted in 2021). These findings are both smaller than previous study estimates for these gasses at the global scale[2,3]. Dr. Cowan explained to Science Feedback that “Emissions of these gases in human breath is not a new discovery and our own global estimates of emissions from the data are actually lower than previous estimates, which are all cited in the manuscript”. So, the Dawson study actually demonstrated breathing may be even less consequential for global warming than studies have previously thought, which was already very low. And yet, these previous studies did not result in viral tabloid and social media attention. Overall, when all of the 430 megatonnes of GHGs (CO2e) emitted in the UK in 2021 are considered, not just methane and nitrous oxide, human breathing contributes only 0.013% of that. The annual impact of breathing would be virtually invisible when stacked up alongside all the actual drivers of global warming in the UK. It would take up only 0.0539 Mt CO2e on the y-axis of Figure 2 which extends from 0 to 800 Mt CO2e. Figure 2 – Summary: of historical greenhouse gas emission estimates in the UK from all anthropogenic sources. Total net greenhouse gas (GHG) emissions in 2020 in the UK were 406 Mt CO2e. Carbon dioxide, which is not increased from human breathing, is the dominant GHG emitted, accounting for 79% of emissions in 2020. According to Dawson et al (2023), human breathing in the UK would only take up 0.0539 Mt CO2e on the y-axis of this figure. The estimated uncertainty in total net GHG emissions in 2020 was ± 3%, at a 95% confidence level. The unit “Mt CO2e” refers to the megatonnes of greenhouse gas emissions in carbon dioxide equivalent units (source). The study has been widely misrepresented; millions of people mislead Major sources of GHG emissions can be reasonably considered “bad for the environment” in reference to their effects on global temperatures, which can lead to a wide-range of climate change related impacts for the natural world. Slow-onset impacts include sea level rise, salinization, ocean acidification, glacial retreat, land degradation, desertification and loss of biodiversity[4]. Climate change has caused losses and damages on terrestrial, freshwater, and ocean ecosystems worldwide[1]. But as demonstrated above, even though human breathing does increase atmospheric concentrations of two GHGs, methane and nitrous oxide, breathing as a GHG source is virtually inconsequential for global warming (and the “environment”) in comparison to major sources like burning fossil fuels, deforestation, and intensive agricultural practices. The widely-shared Daily Mail article is not just a misrepresentation of the words of the study’s authors, it is also factually inaccurate. Science reporter Jonathan Chadwick, who had interviewed Dr. Cowan about the study, writes in the Daily Mail article that “Methane and nitrous oxide in the air we exhale makes up to 0.1 per cent of the UK’s greenhouse gas emissions, scientists say.” But the authors never said this. As Dr. Cowan, corresponding author of Dawson et al (2023), explains: “The total contribution to the UK’s greenhouse gas emissions from human breathing is estimated to be 0.013%, which was clearly communicated to the writer before publication of the article” Further down in the Daily Mail article, Mr. Chadwick contradicts the headline by stating that the 0.05% of methane and 0.1% of nitrous oxide emissions in the UK estimated to be from human breathing does not equate to “0.1% of the UK’s greenhouse gas emissions”. He writes: “Dr Cowan stresses that each of these percentages relate specifically to these respective gases, not all of the UK’s greenhouse gas emissions as a whole.” We reached out to Mr. Chadwick for comment and will update this review if new information becomes available. According to Bob Ward (Policy Director at Grantham Research Institute, LSE), the exploitation of the UK’s ineffective press regulation explains the long track record of climate misinformation from the Daily Mail. This would not be the first time the Daily Mail started a wave of inaccurate climate-related claims just from publishing one article. In 2017, a regulatory ruling led to the Daily Mail admitting multiple inaccuracies in an article on global warming, but the false information (including manipulated graphs since taken down from MailOnline) had already been widely shared and repeated in over 150 different articles. The Dawson study does not state or conclude that breathing is bad for the environment nor that breathing is, or may be, fueling global warming. Despite this reality, the following inaccurate headlines have been published by tabloid press, hyper-partisan websites, and others claiming the study authors say breathing is bad for the environment: Now scientists say BREATHING is bad for the environment: Gases we exhale contribute to 0.1% of the UK’s greenhouse gas emissions (Daily Mail (MailOnline))* ‘Anti-human’: Scientists claim breathing is ‘bad’ for the environment (Sky News Australia)* NEW “SCIENCE” — Humans Breathing Are Bad for the Climate (The New American) Inaccurate headlines published claiming the study authors say breathing is, or may be, fueling global warming include: Humans may be fueling global warming by breathing: new study (New York Post)* Study: Humans Contributing to Global Warming by Breathing (Breitbart News)* Humans Are Fueling Global Warming By Just Breathing, Study Claims (NDTV)* Humans breathing causes ‘global warming’, according to new study (The Post Millennial)* * indicates a mention, quote, or repetition of the inaccurate 0.1% value originating from the Daily Mail. The amount of people who were misled by the overall tabloid media’s inaccurate claims about the Dawson study was further increased on social media. Joe Rogan (7.2 million followers), one of the world’s most influential figures on social media (one of Time 100 Most Influential People, 2022), shared the New York Post article on Facebook. Daily Wire personality Michael J. Knowles (1.5 million followers) posted on Facebook the inaccurate claim that the study means humans have to stop breathing, in addition to the inaccurate claim that methane and nitrous oxide “allegedly contribute to global warming”, which has been well-known for decades based on established and fundamental physics[5]. This inaccurate claim was also made by Blaze Media in their article “UK researchers raise alarm that humans are contributing to ‘global warming’ — by breathing”. Pubity (36 million followers), repeated on Instagram the inaccurate claim that “humans may be fueling global warming by breathing”, and the inaccurate claim that “exhaled methane and nitrous oxide, in addition to carbon dioxide, make up around 0.1% of the UK’s greenhouse gas emissions”. This post alone has been liked over 234 000 times as of 12 Jan. 2023. On the same day the Dawson study was published (13 Dec. 2023), and before the majority of inaccurate and misleading claims appeared in the tabloid media and were shared widely on social media, senior authors Dr. Cowan and Dr. Heal also published an article in The Conversation to help the public understand the study’s main purpose, findings, and implications. In it they stated that the climate change impact of human breathing “pales in comparison to fossil fuel burning and other major sources of emissions”. Dr. Cowan reiterated to Science Feedback: “if you want to be responsible for releasing less greenhouse gasses into the atmosphere, you’d be better off breathing as normal and focusing on other more manageable activities”. Conclusion: The Dawson study found “extremely minimal” impact of human breathing on climate change in the UK, contributing approximately 0.013% of the total greenhouse gas emissions. The factually inaccurate value of 0.1% published by the Daily Mail has been shared and repeated widely. At no point did the authors say human breathing is bad for the environment and fueling global warming. In reality, the senior study authors have said the contributions of human breathing pales in comparison to fossil fuel burning and other major sources of emissions. We have robust data quantifying the actual factors that fuel global warming, such as emissions from energy, transport, and land use. Tabloid press, hyper-partisan websites, and others have misrepresented the scientists words and the study’s findings and implications, misleading millions of members of the public in the process."
https://science.feedback.org/review/claim-cow-burps-not-important-contributor-climate-change-ignores-full-range-greenhouse-gas-emissions-beef-production/,Misleading,"Instagram, Social media users, 2023-12-19","Methane from cows is only a small percentage of total greenhouse gas emissions, it would be produced anyways without cattle, it is not an important contributor to climate change",,"Misleading: Estimates of livestock greenhouse gas emissions do not include land use related emissions, which is one of the most impactful aspects of beef production on climate change. Even so, the seemingly small percentage attributed to US livestock agriculture is still globally relevant because total US emissions are so high. Lacks context: Livestock burps, flatulence, and manure produce 32% of global anthropogenic methane emissions, which drives significantly more warming than carbon dioxide during its relatively short lifetime on a per molecule basis. As beef production increases, so do global methane emissions. Factually inaccurate: Cows are ruminants meaning their stomachs provide ideal anaerobic conditions for the production of methane. The high methane emissions due to the planet’s 1.46 billion domesticated cows would not occur without humans raising such a large number of them.","Reducing methane is critical to achieving global climate targets. Conventional beef and dairy production is a significant contributor to climate change through the release of greenhouse gasses like methane from cow burps. The EPA greenhouse gas estimate does not include land use related emissions from livestock agriculture, which is one of the most impactful aspects of beef production on climate change in addition to cow burps. Methane is a more potent greenhouse gas than carbon dioxide. As beef production increases, so do global methane emissions. The high quantity of cows and the high global warming potential of methane is what makes cow burps impactful on climate change.","Methane claims against cattle are overblown because all emissions from all livestock is only 3.9% of total US greenhouse gas emissions according to the EPA estimate. The emitted methane comes from grass, leaves the atmosphere after 10 years, and then returns to help grass grow. Much of the methane emissions would occur anyways outside the digestive tract of cows.","1 – Lazarus et al. (2021) The climate responsibilities of industrial meat and dairy producers. Climatic change 2 – Emery (2018) Without animals, US farmers would reduce feed crop production. Proceedings of the National Academy of Sciences 3 – Marvin et al. (2023) Natural climate solutions provide robust carbon mitigation capacity under future climate change scenarios. Scientific Reports 4 – Poore & Nemecek (2018) Reducing food’s environmental impacts through producers and consumers. Science 5 – Xu et al. (2021) Global greenhouse gas emissions from animal-based foods are twice those of plant-based foods. Nature Food 6 – IPCC (2023) Chapter 7: Agriculture, Forestry, and Other Land Uses (AFOLU). In: Climate Change 2023: Synthesis Report. Contribution of Working Groups I, II and III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change 7 – Ojima et al. (2020) A climate change indicator framework for rangelands and pastures of the USA. Climatic Change 8 – Hristov (2012) Historic, pre-European settlement, and present-day contribution of wild ruminants to enteric methane emissions in the United States. Journal of Animal Science 9 – Reisinger et al.(2021) How necessary and feasible are reductions of methane emissions from livestock to support stringent temperature goals?. Philosophical Transactions of the Royal Society A","Agriculture is the largest anthropogenic source of methane (CH4) emissions. Livestock agriculture which takes up 80% of global agricultural land but produces less than 20% of the world’s supply of calories, represents about a third of these emissions. It has a much larger emissions profile and impact on climate change than just cow burps. Conventional beef and dairy production results in significant amounts of greenhouse gas (GHG) emissions, which is why improving practices and reducing meat consumption are recognized strategies to mitigate climate change. But in a recent viral Instagram post from 19 December 2023 liked more than 4,000 times, it was claimed that cattle livestock agriculture is not a significant contributor of greenhouse gas emissions. We explain below how this claim is misleading because it fails to account for the full range of emissions linked to beef and dairy production, in addition to methane from cow burps. We also outline how the post caption contains other statements that lack necessary context and are factually inaccurate. The total emissions profile of livestock agriculture is larger than EPA estimates because of land use impacts Agriculture contributes around 10% of all US GHG emissions. In the latest US Environmental Protection Agency’s (EPA) GHG inventory report, livestock agriculture contributed 4.4% of the 6,340.2 million metric tons of CO2-equivalent (CO2-eq) the US emitted in 2021, mostly from enteric fermentation (cow burps) and manure management. The high total emissions of the US may create the impression that livestock agriculture is a relatively small contributor; research has shown that the US meat and dairy industry uses this to undermine climate-related policies[1]. However, 4.4% is still 278.3 million metric tons emitted by US livestock agriculture alone, equating to 69% of the GHG emissions of France for all sectors for the same year, for instance. Furthermore, the use of these EPA estimates to downplay the impact of livestock agriculture on climate change is misleading because they do not include all indirect emissions of CH4, nitrous oxide (N2O), and carbon dioxide, which are significant in the agricultural sector. In addition to enteric fermentation (e.g., cow burps), livestock agriculture involves multiple greenhouse gas emissions sources, such as emissions from manure management (e.g., manure lagoons), feed production (e.g., fertilizer emissions), the energy required to maintain livestock production (e.g., ventilation), and livestock processing and retail (e.g., slaughter and packaging). These all relate to livestock agriculture, but one of the largest emissions sources is still missing: land use impacts. Many GHG estimates typically do not consider the land use impacts of livestock agriculture, despite the fact that it requires extensive land resources. This is the case for the EPA’s estimates. The croplands dedicated to growing livestock feed in the US alone, which is unsuitable for human consumption, cover around three-quarters of the country and involve intensive practices that prioritize yields and negatively affect much of the country’s soils and waterways[2]. Land use impacts in livestock agriculture are especially important for beef production (see Figure 1). Figure 1 – Greenhouse gas emissions for the full supply chain, including land use change impacts, for major animal-based food products measured in kilograms of carbon dioxide-equivalents (CO2-eq) per kilogram of food. Cows are separated as either for beef or dairy production. When land use change impacts and other non-farm sources are included, beef meat production has notably higher greenhouse gas emissions (source). Such extensive land resources dedicated to intensive and environmentally degrading livestock agriculture are blocked from being used to maximize ecosystem carbon sequestration above- (trees and plant biomass) and belowground (soil organic matter). Natural carbon sinks from landscape conservation and restoration are a vital piece of the climate change mitigation puzzle to reduce the impacts of other major sources of GHG emissions, like the transport sector[3]. Land used to intensively grow livestock feed is also land that could be used for producing food suitable for humans to offset meat consumption reductions or crops to foster biofuel production. Expansion of grazing lands and croplands for livestock feed production means less natural vegetation and often much less carbon storage and more carbon emissions. Increases in the demand for beef products within the US can also result in deforestation for pastures in other countries, as beef is a global commodity. Beef production is the leading driver of tropical deforestation, with 2.1 million hectares converted to pastures each year. The lost opportunities for natural carbon sinks and the GHG emissions from land use changes within and beyond the US linked to beef consumption is not represented in the EPAs 4.4% estimate. Including land use and land use change impacts from livestock would significantly increase its emissions profile estimate. For example, considering the average American is ranked second globally for total meat consumption and third for beef consumption, the World Resources Institute estimated the total GHG emissions from the average American-style diet. By including indirect emissions from land-use-change in addition to direct emissions, the total was found to be within the range of per capita energy-related emissions. This indicates that agriculture, primarily because of the total emissions profile of livestock agriculture, can be as impactful for climate change as one of the largest sectors: energy. The total (all direct and indirect emissions) impact US livestock agriculture on top of the EPA’s limited estimate of 4.4% has not yet been robustly calculated. Fortunately, we do have some ideas on how including land use impacts change livestock emission values on the global stage. The FAO estimated that livestock agriculture alone contributes 12% of global GHG emissions in its latest data analysis, with 3.6 billions of tons (Gt, gigaton) of CO2-eq of direct emissions and 6.2 Gt CO2-eq of total emissions (when the full supply chain is considered). Peer-reviewed studies estimate livestock’s contribution at around 15-19% of global emissions, much higher than the EPA’s limited estimate of 4.4%[4-5]. The broader category of “agricultural, forestry, and other land use” is responsible for more than a fifth of the world’s GHG emissions according to the latest IPCC report[6]. This is mainly from land use change (e.g., deforestation for pasture), enteric fermentation (e.g., cow burps), poor pasture and manure management, and nitrogen fertilization. All these factors are linked to beef production. The entire food system, from cultivation, transport, processing, retail, and consumption, contributes 34% of global GHG emissions. Nearly three quarters of that comes from agriculture and its indirect land impacts. Overall, it is clear that cow burps (beef production) are indeed a significant contributor to climate change because they are a major component of agricultural sector emissions when all direct and indirect sources are considered. Cow methane emissions contribute to global warming and would not occur naturally to the same extent Cows are ruminant animals along with goats and sheep; they all release methane (CH4) through burps and flatulence as they digest plants like grass as a result of enteric fermentation. Their burps, flatulence and manure is estimated to contribute 32% of anthropogenic CH4 emissions, and about 40% of global GHG emissions from the agricultural sector in 2011. Contrary to popular belief, cow burps release far more methane than their flatulence. Manure CH4 and N2O emissions represent 7% of global agricultural GHG emissions in 2011. Although CH4 only lasts around 10 years in the atmosphere, it is a much more potent greenhouse gas compared to CO2 and causes long-term damage to climate change mitigation efforts. After being released and within those 10 years, CH4 naturally degrades in the atmosphere through methane oxidation. Chemically, CH4 reacts with ozone to form carbon dioxide and water. Methane-consuming bacteria (methanotrophs) in soil and water can also remove CH4 if in contact. The CO2 and water byproducts of atmospheric CH4 oxidation can then be taken up by ecosystems, for example by photosynthesis in grass to then be consumed by cows, completing this small part of the biogenic carbon cycle. However, this relatively short lifespan and the potential uptake of its oxidized byproducts by plants does not mean CH4 has a neutral impact on global warming. Some context is missing that demonstrates why CH4 methane emissions from cow burps are a significant driver of climate change. First and foremost, the 10 year lifespan of CH4 in the atmosphere is less important than its global warming potential. Why else would one of the world’s largest agribusinesses, Cargill, be investing in cow wearables (i.e., masks) to “tackle methane emissions in the dairy industry”? One molecule of CH4 is over 80 times as potent as one molecule of CO2 in trapping heat in the atmosphere and strengthening the greenhouse effect in the short-term. Even after CH4 oxidizes into CO2, the global warming effect of the original cow burp will continue as CO2 until it is finally photosynthesized by plants. Considering the short-timeframe left for emissions reductions to limit global temperature increase to 1.5°C, any new CH4 emitted to the atmosphere from cows has negative and immediate consequences for climate change mitigation. Second, the fact that CH4 is released by ruminants naturally does not mean it is not an anthropogenic source of CH4 emissions. By drastically increasing beef and dairy production globally, humans have expanded the impact of ruminant CH4 emissions on the atmosphere. Simply put, more cows means more burps and manure which means more CH4 in the atmosphere, in addition to more of the other associated livestock agricultural emissions driving global warming such as land use impacts (e.g., CO2 and N20). The absolute increase and quantity of GHGs is what is most relevant. All human activities have more than doubled atmospheric CH4 over the past 200 years. A single cow produces between 70-120 kg of CH4 gas per year. There are 62% more cows in 2021 than there were in 1961. When all the burps and associated agricultural emissions are added up for today’s 1.46 billion cows, they were responsible for 3.8 Gt of CO2-eq in GHG emissions in 2015. It is also important to clarify that quantities of CH4 emitted by cows in livestock agriculture are not comparable to natural ecosystem CH4 emissions, like from wetlands, geologic seepage, wild animals, termites, wildfires, and permafrost. As CH4 emissions from livestock is an anthropogenic GHG emissions source, this means humans can modify it in an effort to mitigate negative impacts of climate change. Modifying truly natural global-scale CH4 emissions is outside human capabilities, both technologically and logistically. But most importantly, the same scale of CH4 emissions from cow burps would not have occurred naturally as inaccurately claimed in the post. The digestive systems of ruminants like cows provide the optimal anaerobic conditions for CH4 production during enteric fermentation in the specialized “rumen” chamber, the largest part in their stomach (see Figure 2). As plant tissues ferment in the rumen by methanogen microbes for further digestion later, CH4 is produced and released as burps. This process does not occur easily outside of the rumen in landscapes where human managed cows, sheep, and goats consume vegetation. Figure 2 – The global domesticated cow population enabling beef and dairy production is a significant anthropogenic source of CH4 emissions which would not otherwise exist without human involvement. The rumen in the cow digestive system provides the optimal anaerobic conditions for CH4 production via methanogen microbes (source). Non-ruminant CH4 production depends on environmental conditions. Anaerobic bacteria need to decompose biomass under anaerobic conditions, which occurs best in the water-logged soils of wetlands (the largest natural source of CH4 emissions). This would not happen naturally in the open grasslands and pastures used for ruminant grazing. In the US, most rangelands and some pastures occur in semiarid to arid climate zones, while the rest of pastures occur in humid and marginally semi-arid environments[7]. Wetlands are not conducive for livestock agriculture. More cows digesting and fermenting plant tissues means more burping and manure production over pastures and in intensive feedlots. This results in new, additional atmospheric-CH4 that would not have been chemically produced at the same location and to the same extent even when wild ruminants are considered. Wild ruminants in the US like bison, elk, and deer only emit around 4.3% of the emissions from domesticated ruminants, and even pre-settlement wild ruminants only emitted around 86% of today’s domesticated ruminants[8]. Despite misleading claims that cow emissions is just existing carbon that is cycled whereas fossil fuel emissions is new carbon that is added, both of these sources add new carbon to the atmosphere that would not have otherwise been released without human involvement. Any new CO2 and CH4 carbon in the atmosphere will have a warming effect until they are cycled into other carbon pools, regardless of their origin. Emissions are only carbon neutral if they are in equilibrium with the cycle, but human activities have added more carbon than natural cycles can remove, which is why atmospheric GHG concentrations have risen so significantly. Conclusion: Research has shown that reducing CH4is critical to achieving global climate targets, both from fossil fuel sources and from livestock agriculture[9]. Conventional beef and dairy production in particular is a significant contributor to climate change through the release of greenhouse gasses like methane from cow burps. The claim that livestock agriculture, and the burps from cows resulting from beef and dairy production, are not as impactful for climate change as believed is misleading because it is based on GHG estimates that do not include land use related emissions. Even without land use impacts considered, the seemingly small percentage attributed to US livestock agriculture is still globally relevant because total US emissions are so high. Context is also missing in the claim that CH4 from cow emissions has a short-lifespan and is therefore not impactful. In reality, it drives significantly more warming than carbon dioxide during that time on a per molecule basis. As beef production increases, so do global methane emissions. The high quantity of cows and the high global warming potential of methane is what makes cow burps impactful on climate change. Finally, the claim that the same CH4 emissions would occur naturally without beef and dairy cows is factually inaccurate. The enteric fermentation process is unique to ruminants like cows and the methane emissions they produce would not otherwise occur in the pastures and grasslands where cows are raised. Overall, cows are managed by humans so their burps are an anthropogenic source of emissions."
https://science.feedback.org/review/uncertainties-about-future-climate-change-1970s-does-not-invalidate-today-evidence-reality-global-warming/,Inaccurate,"Facebook, Facebook users, 2023-12-09","Scientists predicted global cooling and were wrong, so they are wrong about global warming",,"Inaccurate: During the 1970’s, it was unclear if global cooling linked to atmospheric aerosols would override global warming linked to elevated atmospheric greenhouse gasses. There was no scientific consensus, although more scientists forecasted a future warming than a cooling. Nowadays, available scientific evidence decisively supports the forecast that temperature will continue to increase–and not cool–in the near future.","Some climate scientists in the 1970’s were concerned about the cooling effect of atmospheric aerosols and explored the hypothesis that it might lead to a cooling of the Earth. However, the majority of scientists at that time were actually forecasting global warming for the future. In fact, scientists have warned that elevated greenhouse gasses would cause global warming since the 19th century. Overwhelming observational evidence has resulted in the scientific consensus that global warming is real and human activities, primarily through the emissions of greenhouse gasses, is the main driver.","Scientists in the 1970’s predicted there would be global cooling and a new ice age in the coming decades, but they were wrong. This means they are wrong again about present and future global warming.","1 – Peterson et al. (2008) The myth of the 1970s global cooling scientific consensus. Bulletin of the American Meteorological Society 2 – Sawyer JS (1972) Man-made carbon dioxide and the “greenhouse” effect. Nature 3 – Hansen et al. (1978) Mount Agung eruption provides test of a global climatic perturbation. Science 4 – Lynas et al. (2021) Greater than 99% consensus on human caused climate change in the peer-reviewed scientific literature. Environmental Research Letters 5 – Myers et al. (2021) Consensus revisited: quantifying scientific agreement on climate change and climate expertise among Earth scientists 10 years later. Environmental Research Letters 6 – IPCC (2023) Summary for Policymakers. In: Climate Change 2023: Synthesis Report. Contribution of Working Groups I, II and III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change 7 – Hausfather et al. (2020) Evaluating the performance of past climate model projections. Geophysical Research Letters","In the 1970’s, some popular media outlets were reporting on the supposition that a new ice age could be coming in the following decades. Of course, this never came to pass. We are now in the midst of rapid global warming, largely due to anthropogenic emissions of greenhouse gasses. Multiple temperature records indicate an increase in average global temperature of at least 1.1°C since record keeping began in the second half of the 19th century. However, these historical popular media reports are often used today to challenge global warming and climate change science. In social media posts such as the one featured below in Box 1, it is claimed that because some scientists were studying the possibility of a global cooling that did not end up happening, science must be wrong today about global warming. But scientists in the 1970’s were not entirely certain that global temperatures would increase or decrease in the coming decades. Global warming due to elevated greenhouse gasses was already being modeled, but new research indicating the potential cooling effects of atmospheric aerosols made it necessary to study whether their cooling effect or the warming effect would dominate in future climate change. That said, more scientific studies were forecasting a future warming than a cooling during the 1970’s. A scientific consensus was eventually reached on the fact that the warming influence of greenhouse gasses dominates the cooling effect of aerosols. There was no scientific consensus on global cooling in the 1970’s The idea that scientists in general were predicting an impending global cooling in the 1970’s is wrong[1]. In 2008, a study investigated whether there was any agreement on this topic in the scientific literature. The authors reviewed scientific studies published between 1965 to 1979 projecting or estimating any aspect of climate change and climate forcing over time scales from decades to a century. Only seven of the papers they found projected cooling, whereas 44 projected warming and twenty either projected no change or did not provide an estimate at all (noted as ‘Neutral’ on Fig. 1). Figure 1 – Papers published during the period from 1965 to 1979 classified as projecting, implying, or providing supporting evidence for future global cooling or global warming[1]. The cooling papers also received less citations in the years immediately following publication, indicating less scientific impact and validation as climate science advanced. British meteorologist John Sawyer’s 1972 global warming projection stands-out among the studies reviewed; his projection that the year 2000 would be 0.6°C warmer turned out to be off by less than 0.1°C[2] (see also Fig 3). The lack of scientific consensus on global cooling in the 1970’s is also confirmed in a national survey of scientists in the United States called “Climate Change to the Year 2000: A Survey of Expert Opinion”. Following the especially cold 1976/1977 winter in the eastern U.S., 24 leading climate scientists across the country were surveyed in 1978 by the National Defense University and collectively “tended to anticipate a slight global warming rather than a cooling”. The leading theory on future climate change in the decades before, during, and after the 1970’s has been that of a climate warming due to greenhouse gasses. Ever since the first demonstrations of the greenhouse effect over a century ago and the awareness that humans increasingly emit greenhouse gasses, scientists have consistently warned about global warming. In the defense of the climate scientists who were concerned about a global cooling trend, global temperatures decreased by about 0.1°C from 1940-1970 and it was legitimate to investigate the causes of this trend and whether it would reverse or not. Atmospheric aerosols from anthropogenic air pollution played an important role in some of the local cooling that was observed (i.e., locally over the industrial areas where they are released). But as air pollution aerosols were reduced, emissions of greenhouse gasses continued, and temperature measurement coverage expanded globally, the cooling trends observed over industrial land areas in the northern hemisphere were no longer significant. By the end of the 1970’s, researchers were beginning to understand that any cooling effects from aerosols, which was one of the main supporting points for global cooling projections, were actually outweighed by the warming effects from the increasing concentrations of atmospheric greenhouse gasses[3]. In fact, the reduction of air pollution aerosols and their cooling effects is now a recognized potential driver of global warming scientists follow closely today. The claim that scientists have repeatedly predicted false environmental catastrophes since the 1970’s has already been shown to be inaccurate by Science Feedback. One of the original global cooling popular media stories was a piece written by reporter Peter Gwynne in Newsweek in 1975. Today, Gwynne is amazed how his nine paragraphs on page 64 are still “misused and misinterpreted” by popular climate change contrarians to somehow contend with several decades of proven climate science. Gwynne has tried to clear the air, writing “it’s time for deniers of human-caused global warming to stop using an old magazine story against climate scientists” in his Inside Science article entitled “My 1975 ‘Cooling World’ Story Doesn’t Make Today’s Climate Scientists Wrong”. While his article exploring the possibility of a cooling due to aerosol pollution was justified at the time it was published, it would not be anymore given the information that has become available since then. The reality of global warming projections and observations since the 1970’s Another important point of context to have in mind is that climate science was advancing in the years leading up to the 1970’s; there was uncertainty on the state of the climate because temperature records at the global scale were lacking. The first satellite measurements were starting by the late 1960’s, but we were not yet sure if temperatures were trending up or down and what the main drivers were. Today, there is overwhelming evidence and scientific consensus that global temperatures are increasing. We have robust records of air temperatures over land and the oceans worldwide thanks to the efforts of thousands of data collectors, scientists, meteorologists, and other researchers. Various research organizations that record global temperature using different data processing methods have reached the same results: temperature is rising. Efforts to independently and impartially analyze temperature records, on behalf of skeptics, have confirmed their veracity repeatedly. When we combine temperature records of indirect proxy measurements over the last two millennia (Fig. 2.top), with all the temperature records taken by direct measurements since 1880 (Fig. 2.middle), the increase in average global temperature of at least 1.1°C is clear. There is strong agreement between multiple independent temperature records; they all show that the globe has warmed (in comparison to the average temperature during the period 1951-1980). Compared to the entire 20th century’s average temperature, every decade since the 1970’s have been comparatively warmer (Fig. 2.bottom). This shift from colder to warmer years follows an observed increase in atmospheric-CO2 concentrations, which is the most significant driver of global warming through the elevated greenhouse effect. Figure 2 – Top: Comparison of temperature record (degrees Celsius) going back in time over 2000 years. Temperature records that are based on indirect proxy measurements are indicated by the blue trendline, while temperature records that were directly measured are indicated by the red trendline (source). Middle: Comparison of consolidated temperature records (degrees Celsius) of multiple datasets and methodologies. The data represents temperature differences (plus or minus numbers on y-axis representing change in degrees Celsius) between the recorded year (x-axis) and a common baseline temperature average for the period 1951-1980 (represented as 0 on the y-axis) (source). Bottom: Yearly temperature compared to the twentieth-century average (red bars mean warmer than average, blue bars mean colder than average) from 1850–2022 and atmospheric carbon dioxide amounts (gray line): 1850-1958 (source). Beyond demonstrating global warming is real through years of global temperature measurements and global change observations, like sea level rise from melting ice caps and glaciers, scientists have also demonstrated and are in agreement that humans are the main cause of global warming through greenhouse gas emissions like CO2. A recent peer-reviewed scientific study analyzing thousands of other peer-reviewed scientific studies found that 99% of the scientific literature confirms human greenhouse gas emissions cause global warming[4]. Among scientists with the most climate-related expertise, the consensus reaches 100%[5]. In the most recent IPCC report (AR6), the very first text line (line A.1.) of the “Summary: for Policymakers” confirms there has been 1.1°C of global warming since the period 1850-1900 and it explicitly identifies CO2 as the leading cause[6]. As an indication of the scientific robustness of AR6, just the contribution from Working Group 1 alone was written by 234 of the world’s leading climate scientists coming from 66 countries. It included nearly 4 000 pages of research based on more than 14 000 scientific papers as supporting references and was critiqued and revised by over 1 500 expert reviewers. Some of the earliest attempts at using computer models to understand climate change in the 1970’s not only projected warming, they were also reasonably accurate. In a study comparing the projections of seventeen historical climate model projections (seven of which from the 1970’s) with actual temperature observations since 1970, all of the models projected warming and the majority were consistent with reality (Fig. 3)[7]. Only three of the models projected temperature changes there were too far from reality and were therefore incorrect (observations fell outside their ranges of uncertainty): two projected more warming and one projected less. Figure 3 – Comparison between global climate model projections (red dots) and temperature observations (blue dots). Model projections are expressed as the change in temperature versus the change in radiative forcing, the “implied TCR”, to provide meaningful model-observation comparisons even if the forcing differs between models. As all models have a positive implied TCR value (y-axis), they have all projected an increase in global temperature. The model name and length of time represented are indicated on the x-axis (source). Box 1. Example of an inaccurate claim that global warming is not real because some scientists once predicted global cooling In this post on Facebook from 9 December 2023, it is claimed that global warming is a paranoia that climatologists created after their predictions of extreme global cooling leading to a new ice-age did not materialize. The caption of the Facebook Reel lists various statements labeled as “facts”, including the inaccurate claims that “Science is wrong on Global Warming” because “Science was wrong on Global Cooling”. This post has been shared hundreds of times and reached thousands of viewers who may not know that global cooling was not a mainstream climate theory in the 1970’s. As we explained above, there were more scientists at that time projecting and modeling future global warming. In addition, the claim that “Science is wrong on Global Warming” is inaccurate because the reality of global warming has been unequivocal for years, verified by overwhelming observational evidence resulting in the scientific consensus. Hypotheses that were investigated in the past by scientists, like the one on global cooling, do not invalidate today’s proven scientific concepts that accurately represent observed reality, like current global warming. Conclusion: Some climate scientists in the 1970’s investigated the possibility of a global cooling that they thought could result from the effects of atmospheric aerosols, but the majority of scientists were actually projecting future global warming. In fact, scientists have warned about global warming for a long time. We now know that 1970’s projections of global warming were reasonably accurate, and average temperatures have increased by at least 1.1°C since record keeping began. Overwhelming observational evidence has resulted in the scientific consensus that global warming is real and human activities, primarily through the emissions of greenhouse gasses, is the main driver."
https://science.feedback.org/review/water-vapor-greenhouse-gas-not-major-driver-global-warming/,Incorrect,"Climate Change is Crap, Facebook users, 2023-11-18",Water vapor is the most abundant greenhouse gas so it is the main cause of recent global warming,,"Flawed Reasoning: Water vapor, which lasts only days in the atmosphere, is ultimately controlled by air temperature and pressure according to thermodynamics. Long-term changes in temperature driven by other greenhouse gasses supersedes water vapor feedbacks. Misleading: Water is only relevant for maintaining the natural greenhouse effect. It is a negligible contributor to the enhanced greenhouse effect which is responsible for global warming.","Water vapor is fundamentally different from the other greenhouse gasses which directly cause global warming. It leaves the atmosphere in a matter of days and its atmospheric concentration is ultimately governed by temperature. It is critical for the natural greenhouse effect, but it is a negligible contributor to the enhanced greenhouse effect. We already know, beyond any reasonable doubt, that human emissions of the other greenhouse gasses is the primary cause of global warming.","Water vapor is the main cause of recent global warming because it is the biggest contributor to the greenhouse effect and the most abundant greenhouse gas by weight and volume. Water vapor is natural and the greenhouse effect is natural, so recent global warming is natural.","1 – IPCC (2021) The Earth’s Energy Budget, Climate Feedbacks, and Climate Sensitivity. In Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. 2 – Sherwood et al. (2018) The global warming potential of near-surface emitted water vapour. Environmental Research Letters. 3 – Gimeno et al. (2021) The residence time of water vapour in the atmosphere. Nature Reviews Earth & Environment. 4 – Cawley (2011) On the atmospheric residence time of anthropogenically sourced carbon dioxide. Energy & fuels. 5 – Kiehl & Trenberth (1997) Earth’s annual global mean energy budget. Bulletin of the American meteorological society. 6 – Soden & Held (2006) An assessment of climate feedbacks in coupled ocean–atmosphere models. Journal of climate. 7 – Anbar et al. (2016) Addressing the Anthropocene. Environmental Chemistry. 8 – Broecker (2012) The carbon cycle and climate change: memoirs of my 60 years in science. Geochemical Perspectives.9 – Kunzig & Broecker. (2009) Carbon scrubbers: taking CO2 out of the air. New Scientist.","Although water vapor is the most abundant greenhouse gas (GHG) by weight and volume, it is not a major driver of long-term climate change and the recent global warming we are experiencing. The opposite is often claimed as a challenge to anthropogenic climate change because it is the most important gas maintaining the greenhouse effect and it is naturally occurring. So, as this claim goes, human emissions of GHGs are not to blame. For example, in this Facebook post from 18 November 2023 a table of data is presented that misleads viewers towards this conclusion. We address that post specifically in Box 1 at the bottom of this article. In the next few sections, we will review more generally why this claim is based on flawed reasoning. Water vapor is different than the other greenhouse gasses There are a few differences between GHGs that are driving global warming, like carbon dioxide (CO2) and those that do not, like water vapor. The ability of a gas to add to or reduce global warming is represented by its effective radiative forcing value (ERF, measured in units of watts per square meter (W.m–2)). The ERF is the energy added (heating) or subtracted (cooling) from the Earth system due to a change in that gasses’ concentration and also their global warming potential, which represents the gasses’ ability to trap heat in the atmosphere compared to CO2 as the standard. The ERF is based on radiative transfer models that account for the gasses’ specific absorption and emission properties. The concept implies a change from the norm; a change in radiative forcing from the conditions that we should normally be experiencing under the natural greenhouse effect which makes Earth liveable. We can estimate the ERF of the main greenhouse gasses, including water vapor, over the industrial era to get an idea of the main drivers of the recent global warming we are experiencing (Fig. 1). From the years 1750 to 2019, out of a total anthropogenic ERF value of 2.72 W.m–2, atmospheric-CO2 has been the most important single driver, contributing 2.16 W.m–2 [1]. The next largest drivers are methane contributing 0.54, ozone at 0.42, nitrous oxide at 0.21, and halogens at 0.41. Stratospheric water vapor, resulting from the oxidation of methane emitted from humans, has an ERF of only 0.05 W.m–2. It is among the least powerful greenhouse gasses humans directly or indirectly emit. As a reminder, because these ERF values are all positive, they represent energy added to the Earth system and increased global warming. Figure 1 – Change in effective radiative forcing from 1750 to 2019 by greenhouse gasses, ozone, stratospheric water vapor, surface albedo, contrails and aviation-induced cirrus, aerosols, and solar. The anthropogenic total category represents the combined positive and negative effects of human activities (everything except solar). The solid bars represent best estimates with very likely (5–95%) ranges represented by the error bars (source). Near-surface water vapor has a similarly low ERF and negligible effect on driving global warming as stratospheric water vapor[2]. Because any increase in water vapor near the surface does not reach the upper-troposphere, the potential positive contribution to global warming is negated by the increased reflectance from humidity-induced low cloud cover. This results in a net-zero or even cooling effect from increased water vapor. In addition to the ERF of GHGs (which considers concentration and global warming potential), we also need to consider how long they stay in the atmosphere contributing to global warming. This is known as the atmospheric residence time, or the average time a molecule of that gas remains in the atmosphere before changing or being removed by natural processes. Gasses with longer residence times will have more time to let their ERF impact global climate conditions, whether they increase (e.g., like CO2) or decrease (e.g., like aerosols) global warming. In a sense, we can assume that the longer the residence time in the atmosphere, the greater the cumulative effect of the gas on the greenhouse effect. The atmospheric residence time of water vapor is extremely short compared to the other GHGs. Water vapor cycles through the atmosphere through evaporation and precipitation within 8–10 days on average (median residence time of 4–5 days)[3]. The average residence time of methane is around 10–12 years, nitrous oxide lasts over 100 years, while fluorinated gasses last weeks to thousands of years. Fluorinated gasses, like hydrofluorocarbons, perfluorocarbons, sulfur hexafluoride, and nitrogen trifluoride, are not only the longest lasting, they are also the most powerful GHGs emitted by human activities (thousands of times greater global warming potential than CO2). For CO2, one molecule may leave the atmosphere after about 5 years, but it is replaced by another CO2 molecule from the ocean or biosphere. The global carbon cycle, with its tight budget of sources and sinks (or stocks), is such that it can take hundreds to thousands of years to really “lock away” the excess CO2 that humans have emitted (primarily through burning fossil fuels which was carbon previously locked away). Therefore, atmospheric-CO2 has a much more lasting impact as a GHG than methane and even nitrous oxidebecause its increase in the atmosphere is independent of its actual residence time[4]. Excess water vapor molecules are gone in the blink of an eye comparatively. This is why water vapor is not a major driver of global warming, even if it is the most abundant GHG. The enhanced greenhouse effect and water vapor feedbacks The previous section discussed the ERF of GHGs and estimated negligible values for stratospheric and near-surface water vapor. This water vapor comes from the oxidation of methane emitted from human activities or from irrigation practices, meaning it is water vapor that we ultimately added to the atmosphere (i.e., a change from the norm). But what about all the water vapor that exists naturally in the atmosphere, evaporating from the land and oceans, condensing as clouds and returning as rain and snow? We’ve known for decades that natural water vapor returns much more infrared radiation to the Earth’s surface than other gasses like CO2[5]. Water vapor is what keeps this planet habitable and keeps us warm; it alone causes around half of the natural greenhouse effect[6]. While fluorinated gasses may have the highest global warming potential and CO2 is driving global warming the most, naturally occurring water vapor is indeed the most important greenhouse gas in the atmosphere. The properties of water vapor have also helped keep the Earth’s temperature stable. For at least two thousand years, average global temperatures barely fluctuated more than a few tenths of a degree Celsius before the industrial revolution (based on proxy data like ice cores). But now there is no question that global temperatures have rapidly risen over the last few decades, resulting from the increased anthropogenic greenhouse gas emissions. The planet is currently more than 1°C warmer than the pre-Industrial average with CO2 alone increasing by 50% over this period. This is known as the enhanced greenhouse effect (Fig. 2). When it comes to understanding recent global warming, it is solely the enhanced greenhouse effect which matters. Figure 2 – Illustration of the global energy balance as affected by the natural greenhouse effect (left) and the enhanced greenhouse effect (right). Water vapor (H2O) plays an important role in maintaining the natural greenhouse effect, not driving the enhanced greenhouse effect. Incoming solar shortwave radiation is represented by the yellow arrows and outgoing terrestrial longwave radiation is represented by the red arrows (source). The claim that because both water vapor and the greenhouse effect are natural, global warming is natural is an example of flawed reasoning. It is an oversimplification which disregards the current understanding that human activities, particularly the burning of fossil fuels, have significantly enhanced the natural greenhouse effect by adding more GHGs to the atmosphere. The enhanced greenhouse effect caused by human activities is impacting global temperatures more than what would have occurred naturally with the pre-Industrial concentrations of GHGs. Water vapor is not relevant when it comes to creating the enhanced greenhouse effect because it is a byproduct of temperature change and not a driver, governed by the Clausius–Clapeyron relation. While the other GHGs remain as gasses in the atmosphere, water vapor is easily condensable. It condenses into precipitation and evaporates back into water vapor as a function of the current temperature and air pressure. So any excess water vapor that should not be there precipitates quickly, and any deficit in water vapor is restored by evaporation as soon as possible. Atmospheric-CO2, on the other hand, does not disappear under normal climate conditions in a matter of days like water vapor. In fact, atmospheric-CO2 has been repeatedly shown to be the primary factor controlling global temperature anomalies (changes). These relationships illustrate that it is not water vapor that drives temperature; it is the reverse. So, unlike the other GHGs, human activities do not significantly increase water vapor directly. Any water vapor that is emitted directly or indirectly (e.g., from irrigation or methane oxidation) is not long-lasting, as described above. Human activities cannot directly control how much water vapor is in the atmosphere because ocean and air temperature does. This is also unlike the other GHGs. Warmer temperatures will create warmer surfaces which promote more evaporation and increases in atmospheric water vapor. Colder air temperatures hold less water vapor, resulting in more precipitation and decreases in atmospheric water vapor. Human activities can influence atmospheric water vapor very indirectly by continuing to drive global warming, raising the atmosphere’s capacity to hold water vapor. There is a clear feedback loop between water vapor and global temperature, where an increase in one leads to an increase in the other. It is one of the most dominant climate feedbacks, explaining why global temperatures are so sensitive to changes in the long-lived greenhouse gasses. As the oceans warm because of the enhanced greenhouse effect resulting from increases in atmospheric-CO2, for example, there will be more water evaporation and more water vapor released to the atmosphere. This excess water vapor can trap even more heat and encourage more evaporation. According to the laws of thermodynamics, water vapor concentration should increase by roughly 7% in the atmosphere with every degree Celsius rise in temperature. So, water vapor does indeed contribute to global warming by reinforcing the enhanced greenhouse effect. But it was the initial contributions of the other anthropogenic GHGs that started this feedback. The reduction of GHGs like CO2 can also reverse the water vapor-climate feedback loop by reducing air temperatures which reduces the amount of water vapor in the atmosphere. Earth’s air temperature does not directly affect the concentrations of the other GHGs; their feedback loops with global warming are different. Ultimately, water vapor is very important for maintaining habitable temperatures and it can have a reinforcing feedback with rising temperatures, but it is simply not in the driver’s seat when it comes to creating and maintaining the enhanced greenhouse effect. Box 1. Example of a misleading claim that water vapor is driving recent global warming. In this 18 November 2023post by the Facebook group “Climate Change is Crap”, a table of data is presented that misleads viewers towards the conclusion that water vapor is driving recent global warming. The post is an image of an undated presentation slide from thelate Dr. Wallace Broecker, American geochemist and Professor at Columbia University. The table features different greenhouse gasses and their relative contributions to the greenhouse effect. While the data is outdated and lacking scientific sources, this slide does illustrate the significant role of water vapor in maintaining the natural greenhouse effect and the negligible amount of water vapor in the atmosphere that humans are responsible for. However, the table is not describing the enhanced greenhouse effect, which is the core issue of global warming and climate change. Without context on the difference between the natural and the enhanced greenhouse effect, viewers are misled to believe that water vapor is driving recent global warming and therefore it is a natural phenomenon and not the result of the human emissions of the other greenhouse gasses. The viewers of this post are further misled to believe that this conclusion is supported by climate scientists like Dr. Broecker, who is explicitly attributed to this post. Ironically, Dr. Broecker is credited with coining the term“global warming” as far back as 1975. He was a strong proponent of reducing greenhouse gas emissionsuntil the end of his life, stating in his final academic talk that humanity is not moving quickly enough to slow the production of CO2that is warming the Earth. Broecker regularlyspoke about solving the “CO2crisis”andpublished numerous research articleson the urgent need to reduce atmospheric-CO2concentrations to slow the enhanced greenhouse effect through any means feasible[7-9]. Conclusion: Water vapor may be the most abundant GHG keeping the planet habitable, but it is not a major driver of long-term climate change and the recent global warming we are experiencing. It is incorrect to claim that because water vapor is natural and the greenhouse effect is natural, recent global warming must be natural. Water vapor is fundamentally different from the other GHGs which directly cause global warming. It has a negligible ERF, it leaves the atmosphere in a matter of days, and it is ultimately governed by temperature rather than human emissions. It is more of a consequence of global warming than a cause. We already know beyond any reasonable doubt that anthropogenic emissions of the other GHGs like CO2, methane, and nitrous oxide, is the primary cause of global warming. Water vapor is not relevant when it comes to the enhanced greenhouse effect in the context of recent global warming."
https://science.feedback.org/review/video-ian-plimer-incorrectly-states-human-co2-emissions-not-responsible-for-increased-atmospheric-co2-concentrations-global-warming/,Incorrect,"Conservative Political Action Conference, Ian Plimer, 2023-10-03","Increases in atmospheric CO2 is mainly from natural causes, like ocean outgassing, and not from humans who emit so little in comparison",,"Inaccurate: Though annual human CO2 emissions are much smaller than natural carbon cycle fluxes, they have steadily accumulated in the atmosphere over the past few centuries because their removal by natural carbon sinks has not increased to the same extent. The present-day anthropogenic CO2 increase is unprecedented in rate and magnitude compared to at least the last 800,000 years.  Incorrect: Ocean outgassing, which amplifies natural climate variations on timescales of hundreds-to-thousands of years, cannot explain the magnitude of the present-day atmospheric CO2 increase or the fact that ocean carbon has also been rapidly increasing since the beginning of the industrial era. Atmospheric measurements pinpoint fossil fuel emissions as the primary source of the rapid buildup of atmospheric CO2.","Multiple independent lines of evidence indicate that the present-day increase in atmospheric CO2 is caused by human emissions from fossil fuels and land use change. A significant fraction of annual CO2 emissions remains in the atmosphere each year and has steadily accumulated since the onset of the industrial era, driving global warming. Ocean temperature-CO2 feedbacks are important in millennial-scale glacial-interglacial transitions but do not explain the current atmospheric CO2 increase.","Human emissions could not be driving global warming since they are a small fraction of natural emissions. Temperature actually drives CO2, not the inverse. So the current rise in atmospheric CO2 is caused by ocean outgassing, not human emissions.","1 – Grantham Research Institute on Climate Change and the Environment (2022) Why does climate change get described as a stock-flow problem? 2 – Friedlingstein et al. (2022) Global Carbon Budget 2022. Earth System Science Data 3 – Lan et al. (2023) Trends in globally-averaged CO2 determined from NOAA Global Monitoring Laboratory measurements 4 – IPCC (2021) Global Carbon and other Biogeochemical Cycles and Feedbacks. In Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change 5 – IPCC (2021) The Earth’s Energy Budget, Climate Feedbacks, and Climate Sensitivity. In Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change 6 – DeVries (2022) The Ocean Carbon Cycle. Annual Review: of Environment and Resources 7 – Henry (1803) Experiments on the quantity of gases absorbed by water, at different temperatures, and under different pressures. Philosophical Transactions of the Royal Society of London 8 – Bauska et al. (2021) Abrupt changes in the global carbon cycle during the last glacial period. Nature Geoscience 9 – IPCC (2021) Changing State of the Climate System. In Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change 10 – Keeling and Graven (2021) Insights from Time Series of Atmospheric Carbon Dioxide and Related Tracers. Annual Review of Environment and Resources 11 – Graven et al. (2022) Radiocarbon dating: going back in time. Nature","Dr. Ian Plimer, a former mining geologist, spoke at the Australian Conservative Political Action Conference (CPAC) in Sydney on 2 October 2022. A video clip of the talk was posted on Facebook a year later, and as of 1 December 2023, it has been liked over 5,200 times and shared over 3,700 times. CLAIM 1 (Inaccurate):: “No one has ever shown that human emissions of CO2 drive global warming … and if it could be shown, then you would have to show that the 97% of emissions which are natural do not drive global warming.” While anthropogenic fossil fuel carbon dioxide (CO2) emissions are indeed only a small fraction of annual natural emissions, they play a disproportionately powerful role in driving global warming. This may seem counterintuitive, but it becomes more apparent when we treat atmospheric CO2 as a stock-flow problem[1]. In this framework, the atmospheric CO2 content is the stock while the input and removal of CO2 to the atmosphere are the flows. The issue is that since the onset of the industrial era, human emissions have increased the input of CO2 to the atmosphere, whereas CO2 removal through natural processes has not increased to the same extent. The result of this annual flow imbalance is an increasing stock of atmospheric CO2, driving global warming. The carbon cycle describes how carbon moves between different reservoirs or stocks in the earth system. On timescales up to millennia, the most important natural exchanges are between the atmosphere, ocean, and terrestrial biosphere. Each year, CO2 is released to the atmosphere through ecosystem respiration and fire, and a nearly equal amount is taken up through photosynthesis; there are also air-sea CO2 fluxes largely balanced in both directions. These processes were more or less in equilibrium in the two millennia before the industrial era such that atmospheric CO2 concentrations remained relatively stable (Fig. 1, top). Geologic exchanges typically occur on much longer timescales via sediment burial, volcanic outgassing, and rock weathering. However, since the beginning of the industrial era, human activity through burning fossil fuels has rapidly released carbon stored in geologic reservoirs directly to the atmosphere, with emissions steadily increasing up to the present. Human-induced land-use changes (mainly deforestation) have also transferred carbon from the terrestrial biosphere to the atmosphere much more rapidly than pre-industrial conditions. Though natural removal processes of land and ocean CO2 uptake, or sequestration, have also steadily increased, they have not fully kept pace with increased emissions, taking up around 55% of the total anthropogenic perturbation[2]. The atmospheric CO2 stock reflects this net flow imbalance. Annually-averaged CO2 concentrations have risen without interruption since the beginning of atmospheric measurements in 1958, and the rate of increase is also growing[2,3]. Atmospheric CO2 concentrations have increased from approximately 278 parts per million (ppm; equivalent to 590 gigatons of carbon (GtC) as 1 ppm = 2.124 GtC) in 1750[2] to 417 ppm (886 GtC) in 2022 (Fig. 1, top)[3]. These concentrations are unprecedented in the last 2 million years, and the rate of CO2 increase over the past century is at least 10 times faster than at any other time during the last 800,000 years[4]. This CO2 increase is estimated to contribute to a global surface air temperature warming of 1.01°C since 1750 (90% confidence interval of 0.74°C to 1.41°C), the largest-magnitude climate perturbation over the industrial period[5]. Figure 1 – Atmospheric CO2 concentrations (ppm, top) and global surface temperature anomaly (°C, bottom) over the past 2000 years. From Climate Lab Book. For a more detailed picture, we can examine the specific flows between reservoirs causing the present-day atmospheric CO2 increase using a recent best-estimate assessment of the global carbon cycle for the 2012–2021 decade (Fig. 2)[2]. Average annual fossil fuel emissions over this period are estimated to be 9.6 GtC yr−1 (GtC per year). Dividing this value by the average annual CO2 fluxes from the land (130 GtC) and ocean (80 GtC) yields an estimate of a fossil fuel perturbation of around 4%, comparable to Dr. Plimer’s 3% value (they would be closer using older data as emissions have been increasing). Adding land-use changes (1.2 GtC yr−1) and subtracting sequestration by terrestrial (3.1 GtC yr−1) and marine (2.9  GtC yr−1) carbon sinks yields an average 2012–2021 atmospheric CO2 increase of 5.2 GtC yr−1, or 2.46 ppm yr−1. Figure 2 – Carbon cycle reservoirs (GtC, filled circles) and average annual fluxes (GtC yr−1, arrows) for 2012–2021 (from Figure 2 of reference 2). Thin arrows show the background natural carbon exchanges (estimated around 1750) and thick arrows show the anthropogenic perturbation. CLAIM 2 (Incorrect):: “It’s not CO2 that drives temperature; it’s the exact inverse.” We’ve known for 200 years from chemistry the inverse solubility of CO2, that warm water holds less CO2 as it warms. “We see it from the ice cores … when we have natural warming, some 650–6000 years later we have an increase in CO2.” In his second claim, Dr. Plimer posits that the present-day atmospheric CO2 increase is from the ocean releasing CO2 in response to past natural warming, not human emissions. However, this claim fundamentally overlooks multiple sources of evidence showing a massive influx of anthropogenic CO2 to the climate system. While the ocean does respond to warmer temperatures by outgassing CO2 during glacial-interglacial transitions on timescales of hundreds-to-thousands of years, this mechanism does not explain observations of the rapid and unprecedented rise of atmospheric CO2 concentrations since the onset of the industrial era. The ocean reservoir contains tremendous amounts of dissolved carbon (Fig. 2, circles), owing to the chemistry of CO2 in seawater which allows it to be partitioned across different ions[6]. Like many gases, the solubility of CO2 decreases with temperature, which indeed has been known for over 200 years[7]. A consequence of this inverse solubility relationship is that the ocean is able to hold less carbon as it warms, assuming other conditions are held fixed[6]. This mechanism contributes to amplifying high-latitude temperature changes on timescales of hundreds-to-thousands of years. Due to the slow timescales of deep ocean circulation, the ocean takes centuries to equilibrate to the initial surface temperature perturbation. For example, recent paleoclimate studies indicate that Antarctic temperatures generally precede atmospheric CO2 changes by around 500–650 years (90% confidence interval) during glacial-interglacial transitions, at the far low end of Dr. Plimer’s range[4],[8]. Though important for paleoclimate variations, this mechanism is unable to account for the recent staggering rise of atmospheric CO2 (Fig. 3), which has reached levels unprecedented over the last 2 million years and is increasing at least 10 times faster than at any other time during the last 800,000 years[4]. Moreover, the several centuries prior to the rapid rise of atmospheric CO2 in the industrial era featured slight global cooling[9] (Fig. 1, bottom), contrary to Dr. Plimer’s hypothesized warming. Figure 3 – Atmospheric CO2 concentrations (ppm, top) and Antarctic temperature anomaly (°C, bottom) over the past 800,000 years. From British Antarctic Survey. A glaring problem with Dr. Plimer’s claim is that ocean carbon has been increasing since the industrial era. The schematic Fig. 4 shows a recent best-estimate assessment of the anthropogenic global carbon cycle perturbation for cumulative 1850–2021 changes (left side) and average fluxes over the 2012–2021 decade (right side)[2]. For cumulative 1850–2021 changes (left side), ocean carbon content – estimated from several ocean biogeochemistry models and observation-based data products – increased by 175±35 GtC (mean±1 standard deviation). During that time, total emissions from fossil fuels and land-use change were 670±65 GtC, while atmospheric CO2 concentrations increased by only 275±5 GtC and terrestrial carbon storage by 210±45 GtC. Even considering uncertainties, it would be extremely difficult to close the remaining carbon imbalance without ocean CO2 uptake. Average fluxes for the recent 2012–2021 period (right side) indicate that the rate of ocean carbon sequestration has increased, with uptake rates almost 3 times faster than the 1850–2021 average. Figure 4 – Anthropogenic global carbon cycle perturbation (from Figure 14 of reference 2). Left: cumulative 1850–2021 changes (GtC). Right: average fluxes over 2012–2021 (GtC yr−1); note that these correspond to the thick arrows in Figure 2. Several atmospheric measurements provide further corroboration that human emissions are the source of rising global atmospheric CO2 concentrations[4],[10]. Figure 5, top, shows observations of monthly CO2 concentrations at Mauna Loa Observatory and the South Pole, with concentrations at both stations continuously increasing since measurements began in the late-1950s. Another feature is that CO2 concentrations at Mauna Loa have increased by a few ppm compared to the South Pole, indicating higher CO2 input from the land-dominated northern hemisphere, where most industrialized regions are located. Furthermore, measured atmospheric oxygen (O2) concentrations have been steadily decreasing globally since regular observations began around 1990 (Fig. 5, bottom). Atmospheric O2 concentrations are not affected by ocean CO2 outgassing, so the decreasing O2 concentrations indicate that increasing atmospheric CO2 is primarily driven by an oxygen-consuming process, namely combustion, but also respiration. Figure 5 – Top: Monthly average atmospheric CO2 concentration (ppm) at Mauna Loa Observatory, Hawaii (black) and South Pole (red). From Scripps CO2 program. Bottom: Atmospheric O2 concentrations (expressed as the O2/N2 ratio) at Mauna Loa Observatory. From Scripps O2 Program. Isotope measurements provide additional evidence for a fossil fuel source of increased atmospheric CO2 concentrations[10],[11]. Carbon has two stable isotopes: around 99% exists as carbon-12 (12C) and 1% as carbon-13 (13C). Plants preferentially take up 12C through photosynthesis, so plants and fossil fuels (which are derived from organic matter) are enriched in 12C compared to atmospheric CO2. The global 13C/12C ratio has been decreasing since atmospheric measurements began in the late-1970s (Fig. 6), indicating a plant or fossil fuel source of increasing atmospheric CO2. Furthermore, the unstable radioactive isotope carbon-14 (14C or radiocarbon) is naturally produced in extremely small amounts in the upper atmosphere and is absent from fossil fuels. There has been a long-term decrease in the 14C/12C ratio (interrupted by a pulse from atmospheric nuclear testing), indicating an enhanced 12C source from fossil fuel emissions. Figure 6 – Monthly average 13C/12C ratio (expressed as δ13C) at Mauna Loa Observatory (black) and South Pole (red). From Scripps CO2 program. Conclusion: Dr. Plimer’s claims are incorrect and inaccurate. Overwhelming evidence from carbon budget accounting and atmospheric measurements implicate anthropogenic fossil fuel burning as the main source of the present-day atmospheric CO2 increase. Though relatively small on an annual basis compared to natural fluxes, the steady input of anthropogenic CO2 emissions with only partial removal from natural carbon sinks has resulted in an unparalleled increase of atmospheric CO2 concentrations since the onset of the industrial era. The scientific consensus and evidence for the clear links between human CO2 emissions, the greenhouse effect, and global warming have also been recently addressed in another claim review of Science Feedback. Trends in atmospheric measurements, such as CO2 concentrations increasing faster in the northern hemisphere, decreasing O2 concentrations, and decreasing 13C/12C and 14C/12C ratios, can only be explained by emissions from fossil fuel combustion in the industrialized northern hemisphere."
https://science.feedback.org/review/global-warming-matches-model-predictions-well-misconstrued-claims-new-photosynthesis-study/,Inaccurate,"Twitter/X, Steve Milloy, 2023-11-18",New photosynthesis study shows that Earth is not warming as predicted by climate models,,"Factually Inaccurate: Observations of the increases in global temperature match the uncertainty ranges of leading climate models. In some cases, observed warming exceeds predictions.  Misrepresentation of sources (strawman): New research shows increased photosynthesis potential of plants under global warming scenarios; it does not imply observed global warming: 1) is not happening; 2) is not happening as much as predicted; or, 3) will not continue to happen.","Climate models have forecasted global warming well since the 1970s. New insights on plant photosynthesis under global warming do not invalidate climate models; rather, they help reduce uncertainty in model predictions of future climate change resulting from human emissions of greenhouse gases.",Earth not warming as predicted by (junk) climate models because plant photosynthesis is absorbing more CO2 than imagined. Climate change is a hoax.,"1 – Hausfather et al. (2020) Evaluating the performance of past climate model projections. Geophysical Research Letters 2 – Kim et al. (2020) Evaluation of the CMIP6 multi-model ensemble for climate extreme indices. Weather and Climate Extremes 3 – Carvalho et al. (2022) How well have CMIP3, CMIP5 and CMIP6 future climate projections portrayed the recently observed warming. Scientific Reports 4 – Gudasz et al. (2021) When does temperature matter for ecosystem respiration?Environmental Research Communications 5 – Marcolla et al. (2020). Patterns and trends of the dominant environmental controls of net biome productivity. Biogeosciences 6 – Samset et al. (2023) Steady global surface warming from 1973 to 2022 but increased warming rate after 1990. Communications Earth & Environment","A recent scientific study illustrating the increasing role of photosynthesis under global warming scenarios has been misconstrued to promote climate change denialism. In a November 18th Twitter post, Steve Milloy inaccurately claims the Earth is not warming as predicted by climate models because plant photosynthesis will absorb more CO2 than imagined. Milloy has ties to and defended the tobacco, chemical, and oil and gas industries for years; he considers climate change to be a hoax. His claims are based on his understanding of the study and a November 17th Telegraph article covering the study and have reached over 1.1 million viewers on Twitter. Before addressing the claim inaccuracies, it is necessary to state that they fall outside the scope of the study, which does not investigate current or future global warming. The study’s lead and corresponding author Dr. Jürgen Knauer (Western Sydney University) confirmed to Science Feedback that Milloy’s claims are unrelated to the study and “any conclusions on what our study means with respect to future global warming remain speculative.” Global climate models continue to predict global warming well The Earth is warming as predicted by climate models, contrary to Milloy’s central claim. In fact, we know now that even the first attempts at using early computer models in the 1970’s to predict global warming were reasonably accurate. In a study comparing the predictions of seventeen historical climate model predictions with actual temperature observations since 1970, the majority were consistent with reality (Fig. 1)[1]. After ensuring the performance of each model can be compared fairly (by accounting for differences in historical climate forcings), the results showed that 14 of the models predicted the warming that has been observed (i.e., observations within the uncertainty range). Only three of the models were off: two predicted more warming and one predicted less. Figure 1 – Comparison between global climate model predictions (red dots) and temperature observations (blue dots). Model predictions are expressed as the change in temperature versus the change in radiative forcing, the “implied TCR”, to provide meaningful model-observation comparisons even if the forcing differs between models. The model name and length of time represented are indicated on the x-axis (source). In addition to the overall assessments presented in Figure 1, the successful track record of climate models can also be observed on a yearly scale starting from the first predicted year. In 2017, Carbon Brief produced visualizations comparing several original model predictions and actual observed warming for each year since John Sawyer’s (British meteorologist) early 1970’s prediction that the year 2000 would be 0.6°C warmer (he was off by less than 0.1°C). Despite various computational and theoretical limitations as the models developed from simple (energy balance) to advanced (fully-coupled Earth System Models), these predictions have closely matched observations. More visual examples comparing past predictions, or model forecasts, with actual observations of global temperatures can be found here. Another way we can see how well global climate models have performed is to take them as a whole: a multi-model ensemble. Dozens of institutes and labs around the world model past, present and future climate change effects, each developing their own climate model using different approaches. The Coupled Model Intercomparison Project (CMIP) uses a standard experimental framework to average out the predictions of all these coupled models (ocean-atmosphere coupled) as an ensemble of models, which allows us to get statistically more robust predictions with greater confidence and less uncertainty. We can also see where the models agree or disagree and explore why[2]. The most recent multi-model ensemble, CMIP6, featured 49 climate modelling groups and 100 individual climate models. The CMIP3 predictions, for example, have clearly survived the test of time (Fig. 2.top). Multiple records of global temperature data observations follow the multi-model average forecasted by CMIP3 from the year 2000, with all observations falling within the uncertainty range. With the ensemble model developed as part of CMIP5 for the 2014 IPCC AR5, we see that the multi-model averages capture historical and recent warming (Fig. 2.bottom). Figure 2 – Top: Global temperature anomalies (observations, coloured trend lines updated to January 2023) compared to CMIP3 individual simulations performed in 2004 with forcings extrapolated from the year 2000 (black trend line) with model ensemble 95% confidence interval (source). Bottom: Global surface temperature anomalies on a monthly scale (observations, red trend line) compared to CMIP5 climate model predictions (multi-model average, black trend line with 95% confidence interval) until the year 2030 using a baseline period of 1900-2000 (source). Observational data that falls outside the multi-model 5th-95th percentile range can be considered unsuccessfully modelled, and should therefore statistically be observed in one in twenty times due to the variability of Earth’s climate system (e.g., El Niño and La Niña behaviour–which can exercise large influences on global mean surface temperature). The vast majority of temperature observations in Fig. 2.bottom have been within uncertainty ranges of the historical, present, and future (in the case of CMIP5’s pre-2014 simulations) multi-model predictions. There are even some indications that CMIP predictions up to 2020 have underestimated the magnitude of warming we have since observed[3]. Potential increase in photosynthesis does not imply global warming is not happening By also claiming “Hoaxers now blaming plants for absorbing more CO2 than imagined”, Steve Milloy not only promotes climate change denialism, but he misrepresents Dr. Knauer’s study. This is the strawman fallacy. Together with Dr. Knauer, we will briefly explain how the original study is unrelated to and does not support Milloy’s claims. Let’s recall a few concepts. Terrestrial ecosystems play an important role in the global carbon cycle, acting as both sources and sinks of carbon dioxide (CO2). Therefore, terrestrial ecosystems, including plants, affect atmospheric-CO2 levels, which determine the strength of the greenhouse effect and global warming. The ebb and flow of carbon between the atmosphere and ecosystems is called net biome productivity (NBP), featuring the carbon taken up by plants through photosynthesis, called gross primary productivity (GPP), and the carbon released back to the atmosphere, called ecosystem respiration (ER). The difference between these two flows, or fluxes, determines whether an ecosystem is a net sink or source of carbon, in addition to other factors like fires and land use practices. Carbon sinks imply a reduction of atmospheric-CO2 and, possibly, reduced global warming, but an increase in GPP alone is not enough information to tell us if global warming overall will be impacted. There are many questions. Dr. Knauer states how his study is unrelated to Milloy’s inaccurate claims: “In our study we looked only at GPP. We didn’t look at ER or the actual land sink (NBP). Thus we cannot make definite statements on how future increases in GPP, even if they are stronger than expected, influence NBP or global temperatures.” Understanding NBP as a whole can help us add up the global carbon budget and improve our projections of future global warming. It is true that because GPP is fundamental to NBP, any change in GPP will affect NBP and the overall carbon balance of ecosystems. But this relationship is indirect; there are several factors that will influence how much a change in GPP will result in a change in NBP. For example, ER is closely tied to temperature, especially at higher temperatures above 20°C[4]. As temperatures rise, biological processes accelerate and so do respiration rates. If respiration increases under global warming more than photosynthesis (GPP) increases, it would offset the atmospheric-CO2 reductions. Fires, droughts, and other ecosystem disturbances can also influence the difference between GPP and ER. As Dr. Knauer explains: “Since GPP is one component of NBP, a stronger than expected increase in GPP could also lead to a stronger than expected increase in NBP. But there are a couple of reasons why NBP might not follow the same trajectory as GPP. For example, respiration has a strong temperature response and is likely to show a stronger increase than GPP with global warming. Then there are other factors such as fires, droughts, and other disturbances that could increase in frequency and intensity in the future and affect NBP.” So, while plant photosynthesis can be an indicator of potential atmospheric-CO2 reductions, we also need to consider other factors affecting NPB before we can reasonably predict changes to future global warming[5]. Changes in ER and multiple ecosystem disturbances need to be accounted for. Over time, these new insights on the response of plants and ecosystems to climate change can be incorporated into global climate models to further improve our predictions of future global warming. When new data and insights arise like those in Dr. Knauer’s study, scientists revise models in search of even greater accuracy; see here for some of their thoughts on the process. Ultimately, Milloy’s inaccurate claims that the Earth is not warming as predicted by (junk) climate models because plant photosynthesis is absorbing more CO2 than imagined misconstrued Dr. Knauer’s study: “In summary, our study suggests that GPP can be higher than previously expected under future climate change. Our study did not look at how NBP will change with climate change and how that could feed back on global warming. Hence, any conclusions on what our study means with respect to future global warming remain speculative.” Conclusion: Steve Milloy’s claims are inaccurate and unsupported. Climate model predictions have been evaluated and tell us that the global warming we are experiencing today is within the ranges we predicted it to be. Even decades old predictions still hold-up. If anything, evidence suggests warming estimates may have been a bit too conservative and the rate of global warming may be increasing faster than predicted[6]. Milloy’s claims misconstrue and misrepresent the study he uses as support. Increases in photosynthesis, based on new scientific insights, does not imply that global warming is not happening, is not happening as much as predicted, or will not continue to happen."
https://science.feedback.org/review/wall-street-journal-questions-decades-scientific-evidence-demonstrating-elevated-atmospheric-co2-causes-global-warming/,Inaccurate,"The Wall Street Journal, Holman W. Jenkins, 2023-11-03",We do not know if CO2 is the cause of global warming,,"Inaccurate: Evidence has allowed scientists to conclude, beyond reasonable doubt, that elevated atmospheric-CO2 from human emissions is the main driver of global warming. Scientists have quantified how much CO2 has strengthened the greenhouse effect by absorbing and radiating heat and this warming effect matches the observed global temperatures increase.","We know that CO2 causes global warming through the greenhouse effect based on overwhelming evidence from data collected over decades of investigation. There is international scientific consensus that elevated atmospheric-CO2 from human emissions is not just a cause of global warming, it is the leading cause of global warming.",We do not know if CO2 is the cause of global warming because global climate models and temperature records are unreliable.,"1 – Myers et al. (2021) Consensus revisited: quantifying scientific agreement on climate change and climate expertise among Earth scientists 10 years later. Environmental Research Letters 2 – Lynas et al. (2021) Greater than 99% consensus on human caused climate change in the peer-reviewed scientific literature. Environmental Research Letters 3 – IPCC (2023) Summary for Policymakers. In: Climate Change 2023: Synthesis Report. Contribution of Working Groups I, II and III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change 4 – IPCC (2021) The Earth’s Energy Budget, Climate Feedbacks, and Climate Sensitivity. In Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change 5 – Romps et al. (2022) Why the forcing from carbon dioxide scales as the logarithm of its concentration. Journal of Climate 6 – Vose et al. (2021) Implementing full spatial coverage in NOAA’s global temperature analysis. Geophysical Research Letters","In the Wall Street Journal (WSJ), opinion columnist Holman W. Jenkins claims we do not know if carbon dioxide (CO2) is the cause of global warming. Jenkins bases his November 3rd article“The Earth Is Warming, but Is CO2 the Cause?” largely on a recent report from the national statistics agency of Norway. Dozens of other outlets and blogs similarly covered that report. The claim that we do not know if CO2 is the cause of global warming is inaccurate based on a comprehensive body of scientific work, diverse methodologies and data sources, and fundamental physics, as we explain below. A consensus of scientific evidence confirms CO2 from human emissions causes global warming It takes more than the claims of one report to overturn decades of evidence and the international scientific consensus that CO2 causes global warming. There is a long and straightforward history of how we have reached the consensus on anthropogenic climate change, or that CO2 and other greenhouse gas emissions from humans are causing global warming. Nearly all scientists agree humans are causing global warming through greenhouse gas emissions. Among scientists with the most climate-related expertise, the consensus reaches 100%[1]. A recent peer-reviewed scientific study analyzing thousands of other peer-reviewed scientific studies found that 99% of the scientific literature confirms human greenhouse gas emissions cause global warming[2]. Last week, the Fifth National Climate Assessment of the USA (a congressionally mandated interagency report featuring 500 expert contributors) concluded that “global warming observed over the industrial era is unequivocally caused by greenhouse gas emissions from human activities”. The report goes on to explain that CO2 is the primary greenhouse gas humans emit and the principal greenhouse gas that affects Earth’s radiative balance. On the global stage, the reports from the United Nations Intergovernmental Panel on Climate Change (IPCC) represent humanity’s best attempts to synthesize and summarize climate change science. With each IPCC report released, thousands of experts are involved in making sure the statements are accurate and robustly supported in the scientific literature. In the most recent IPCC report (AR6), the very first text line (line A.1.) of the “Summary: for Policymakers” states “Human activities, principally through emissions of greenhouse gases, have unequivocally caused global warming”[3]. The report confirms there has been 1.1°C of global warming since the period 1850-1900 and it explicitly identifies CO2 as the leading cause (Fig. 1). As an indication of the scientific robustness of AR6, just the contribution from Working Group 1 alone was written by 234 of the world’s leading climate scientists coming from 66 countries. It included nearly 4000 pages of research based on more than 14 000 scientific papers as supporting references and was critiqued and revised by over 1 500 expert reviewers. Figure 1 – The contributions of different drivers to global warming from the present time period (2010-2019) relative to the time period of 1850-1900 (source). The estimates of warming (red) and cooling (blue) from radiative forcing studies (panel (c)) are based on both direct emissions into the atmosphere and their effect, if any, on other climate drivers. Clear links between human CO2 emissions, the greenhouse effect, and global warming We have high resolution records of CO2 increase across the globe in more recent decades, with even relatively robust proxy records before and since the start of the Industrial Revolution (which was when humans started to really harness fossil fuels like coal, petroleum, natural gas). As we burned fossil fuels throughout the industrial era, we released CO2. With current global atmospheric-CO2 concentrations now approaching 420 parts per million, human emissions have increased CO2 concentrations in the atmosphere by 50% since the year 1750 (Fig. 2). Figure 2 – Human emissions of CO2 (grey line, right y-axis) from activities like burning fossil fuels, deforestation, and intensive agricultural land use practices represent only a small portion of total annual emissions on Earth (human and natural emissions), but they have accumulated enough year-over-year to increase atmospheric concentrations significantly (blue line, left y-axis) (source). We have known for over a century that CO2 is a key greenhouse gas that can and is strengthening the greenhouse effect in the atmosphere. Like the other known infrared-absorbing greenhouse gases, CO2 absorbs and re-emits heat and therefore maintains a higher temperature in the atmosphere than non-greenhouse gases (Fig. 3). Since the first experiments of mid-19th century scientists, countless more studies have tested and validated the warming effect of increased atmospheric-CO2. Figure 3 – The surface and atmosphere of the Earth absorbs solar radiation from the Sun and re-radiates it as longwave radiation. Some of the longwave radiation makes it back to space (blue shaded section). The radiation that does not, gets trapped in the atmosphere by greenhouse gases like CO2, which all have different radiative forcing strengths based on the frequencies (or wavelengths) they affect and their atmospheric concentration, among other factors. This is the greenhouse effect (red shaded section), because more longwave radiation persisting in the atmosphere produces higher air temperatures (source). Global temperature records resulting from the efforts of thousands of data collectors, scientists, meteorologists, and other researchers across the planet, demonstrate a clear increase in temperature in recent decades that is unprecedented (Fig. 4). Various government, academic, and independent research organizations that record global temperature using varying data processing methods have reached the same results: temperature is rising. These methods and the datasets themselves are based on the gold standard of scientific publication involving peer-review critiques and re-analysis from external experts. Efforts to independently and impartially analyze temperature records, on behalf of skeptics, have confirmed their veracity repeatedly. This is how we can say the data is reliable and represents our best scientific efforts. Figure 4 – Top: Comparison of temperature record (degrees Celsius) going back in time over 2000 years. Temperature records that are based on indirect proxy measurements are indicated by the blue trendline, while temperature records that were directly measured are indicated by the red trendline (source or source). Bottom: Comparison of consolidated temperature records (degrees Celsius) of multiple datasets and methodologies. The data represents temperature differences (plus or minus numbers on y-axis) between the recorded year (x-axis) and a common baseline temperature average for the period 1951-1980 (represented as 0 on the y-axis) (source). So, we know elevated CO2 comes from human activities, which strengthens the greenhouse effect, and there has been a significant increase in global temperatures as a result. In the IPCC AR6, greenhouse gases are quantified to be (very likely) the main driver of global warming among all the different drivers (Fig. 1). Other greenhouse gases, such as methane, have been heating the atmosphere since 1850 due to their increased concentrations, but most of the temperature increase can be attributed to CO2. Each greenhouse gas has a specific effective radiative forcing (ERF, measured in units of watts per square meter (W.m–2)) which represents the energy added (heating) or subtracted (cooling) from the Earth system due to their change in concentration and their global warming potential (GWP). Calculations of the ERF of CO2 since 1850 place it at 2.012 ± 0.241 W.m–2, while the next largest is methane (CH4) at 0.496 ± 0.099 W.m–2, followed by nitrous oxide (N2O) at 0.201 ± 0.030 W.m–2. Because these values are all positive, they represent energy added to the Earth system. They are calculated from a combined approach that uses the stratospheric-temperature-adjusted radiative forcing from radiative transfer models and adds the tropospheric adjustments derived from Earth system models[4]. The relationship between CO2 and global temperatures is so clear that we can trace recent global warming alongside recent atmospheric-CO2 increases and even predict temperatures based on the concentration of atmospheric-CO2. With each doubling of CO2, its radiative forcing increases by about 4 W.m–2, meaning there should be a logarithmic relationship between temperature and atmospheric-CO2 concentration[5]. When we plot both with CO2 on logarithmic scale and incorporate a time lag for global temperatures to respond, this is exactly what we see (Fig. 5). Figure 5 – Top: Comparison of yearly global surface temperatures (left y-axis) with atmospheric-CO2 concentrations (grey line, right y-axis) since 1850. Yearly temperature bars are relative to average temperature from 1850-2022 with blue bars indicating a cooler than average year and red bars indicating a warmer than average year (source). Bottom: Global temperatures versus atmospheric-CO2 on a logarithmic scale (as described in a previous claim review on Climate Feedback). This is why we know CO2 causes global warming. It traps infrared radiation near the Earth’s surface and is the most important driver of global warming. It may not have the highest GWP, but its concentration has increased the most in the atmosphere (in absolute terms) and it has the highest ERF. From 1990 to 2022, CO2 caused approximately 78% of the increase in global warming attributed to greenhouse gases. In summary, the greenhouse gases overall cause the most global warming of all the climate change drivers, and CO2 causes the most global warming of all the greenhouse gases (Fig. 1). Climate change misinformation is fuelled by misconceptions, but the science is clear Jenkins’ inaccurate claim in the WSJ refers heavily to only one source, a recent report published by Statistics Norway entitled “To what extent are temperature levels changing due to greenhouse gas emissions?”. The report authors, who do not have significant expertise in climate science, think that global climate models are probably unable to detect anthropogenic climate change. However, this climate change skepticism talking point has been addressed regularly over the years. The Statistics Norway report is problematic for numerous reasons, as demonstrated by both Dr. Rasmus Benestad, who is a senior scientist at the Norwegian Meteorological Institute with a background in physics and statistics, and by Dr. Stefan Rahmstorf, who is a physicist, oceanographer, and professor at Potsdam University. Among the main issues with the report, the authors conflate methods of statistical models with physics-based models and misunderstand the purpose, methods, and effects of model calibration or “tuning”. Their claim that solar activity can be an explanation for global warming has long been investigated and the observations are incompatible with the hypothesis that the Sun could be the cause of global warming. In fact, the amount of energy received from the sun has decreased while the climate has warmed over the last few decades. The authors also disregard physical evidence of global-scale climate change, like sea level rise, and CO2’s greenhouse gas physical properties (proven in laboratories and by physics) by claiming local “noise” in temperature datasets makes it “impossible to determine how much of the temperature increase is due to emissions of CO2”. Local-scale datasets cannot always be expected to reflect global warming trends due to the chaotic nature of local weather. If it was only random fluctuations in temperature at the global scale, then we would expect as many decreases in temperature as increases. In reality, almost all weather stations show warming because the natural variability at the local scale, or the noise, is drowned out. The limited selection of data analyzed in the report is a poor representation of the global situation and leads to cherry picking data. This enables one to find spurious correlations or conceal significant correlations to support pre-existing biases. The authors also propose changes in Earth’s orbit as an explanation for recent climate change. While climate scientists have long been aware that changes in Earth’s orbit have caused past climate change over long periods of time, this is not something that can explain recent global warming, which is happening at a much faster rate. Both the IPCC AR6 and the NCA5 report outline how natural climate change drivers throughout the industrial era, like solar radiation and volcanic aerosols, have had negligible and regionally variable climate effects. Jenkins also inaccurately claims that temperature records are dishonestly managed and unreliable (claims previously addressed by Climate Feedback here and here). Despite stating “the Earth is warming” in the title of his opinion piece, Jenkins contradicts himself by later writing “a future climate scandal” might in fact reveal the opposite. Claims that temperature datasets are corrupted are regularly debunked. The temperature records maintained by NOAA come from a mix of sources and have been compiled over the years to ensure full global and historical coverage. These methods are tested and verified by other bodies and researchers independent of NOAA. With each expansion of the dataset to include earlier years, more geographic locations, and higher-quality data, NOAA and other researchers using the data publish and explain the new methods and the impacts of their results. For example, researchers recently investigated new NOAA data reaching back to the year 1850 and found even more warming in the Arctic than previously estimated[6]. It is with these updates that we improve climate science and reduce the range of temperature uncertainties, which are inevitable in any effort to quantify natural phenomena at the global scale. Conclusion: In America’s second largest print newspaper, with an online audience of millions of subscribers, Jenkins questions whether we know if CO2 drives global warming. The two authors of the Statistics Norway report claim we cannot know. However, the evidence that has been analyzed by thousands of leading scientists around the world has allowed them to conclude that, to the best of human knowledge and beyond reasonable doubt, we know that increased atmospheric-CO2 from human activity is causing global warming. UPDATE (30 November 2023): We updated this review to include a link to Dr. Stefan Rahmstorf’s rebuttal on RealClimate, published on 29 November 2023, and added a sentence to further explain the differences between analyzing local and global temperature datasets."
https://science.feedback.org/review/claim-current-climate-change-explained-natural-cycles-volcanic-activity-does-not-have-scientific-support/,Incorrect,"Twitter/X, Social media users, 2023-09-02","The cyclical activity of the Sun as well as other variations in solar and earth activity, and NOT anthropogenic CO2 emissions, are responsible for climate change",,"Incorrect: There is no evidence that natural variation in the Sun’s energy output, changes in the position of the Sun relative to the Earth, or volcanic activity on Earth can account for ongoing climate change. By contrast, all observations are consistent with the fact that human emissions of greenhouse gases are causing ongoing global warming.","Solar energy output does change slightly over short-term as well as long-term cycles. However, the expected effects due to these natural cycles are far below the threshold that could account for current climate change.","The cyclical activity of the Sun as well as other variations in solar and earth activity, and NOT anthropogenic CO2 emissions, are responsible for climate change",IPCC (2023) Climate Change 2023 Synthesis Report. Date accessed September 15 2023 Crowley (2000) Causes of climate change over the past 1000 years. Science Santer et al. (2013) Human and natural influences on the changing thermal structure of the atmosphere. Proceedings of the National Academy of Sciences Joshi and Jones (2009) The climatic effects of the direct injection of water vapour into the stratosphere by large volcanic eruptions. Atmospheric Chemistry and Physics Hall and Waugh (1997) Tracer transport in the tropical stratosphere due to vertical diffusion and horizontal mixing. Geophysical Research Letters,"In a post on X (formerly Twitter) on September 2, a social media user (Robin Monotti) posits that the primary reason for climate change is the cyclical activity of the Sun and the Earth, with volcanic activity also playing a role. Overall, it appears that Monotti’s aim is to imply that while human activity and CO2 emissions might be playing some role in climate change, these are not the main factors. As of the date of publication of this review, the post has been reposted about 5 thousand times and viewed over 1.2 million times. However, in its most recent report on climate change, which constitutes an authoritative review of scientists’ work around the world, the Intergovernmental Panel on Climate Change (IPCC) explains that, compared to the 19th century, global surface temperature has increased by more than 1°C, and this increase can be entirely explained by the influence of human activities. In contrast, the impact of natural (solar and volcanic) drivers on global temperatures is estimated to be 0 plus or minus 0.1°C over this same period[1] (Figure 1). Figure 1 – Drivers of global warming for the period 2010–2019. The figure shows that the observed warming is consistent with the warming that can be calculated from human influence, the warming being mostly a consequence of added greenhouse gases (GHG). Taken from Figure 2.1 from the Climate Change 2023 Synthesis Report of the IPCC. In his post, Monotti does not specifically state how the cyclical activity of the Sun as well as other factors can cause climate change, but he implies that variation in solar activity and in the Sun’s orbit relative to other celestial bodies, and changes in the Earth’s orbit are sufficient to explain ongoing climate change without recourse to greenhouse gas emissions and human activity. However, there is no evidence that any of these factors can explain the magnitude of the change in the earth’s climate that we are currently experiencing[2]. To address these claims, it is instructive to consider why scientists agree that climate change is man-made and why there is a consensus that it is due to greenhouse gases. On the one hand, this conclusion rests on direct measurements of greenhouse gases in the atmosphere. These measurements have shown that atmospheric CO2 increased by more than 40% from 1800 to 2019. How do we know that this increase is due to human activity? First, the circumstantial evidence: CO2 levels have increased most precipitously since 1970, which was a period that also witnessed a pronounced increase in global energy consumption. Further, the conclusion is based on analysis of the different carbon isotopes detected. Carbon comes in three naturally occurring isotopes: 12, 13, and 14. These numbers refer to the numbers of neutrons in the nuclei of these different isotopes, and the different isotopes are derived from different sources. Plant material is enriched in 12C (Carbon 12), and it is precisely this isotope that has become enriched in the atmosphere. The only valid explanation is that this enrichment is due to the burning of fossil fuels and the release of 12C. The changes in climate, meanwhile, are based on scientists’ understanding of how heat is trapped by greenhouse gases. Models that seek to explain changes in climate and their causes have identified anthropogenic greenhouse gas emissions as the only factor that can reasonably explain the observed global warming. Of course, natural causes and variations can affect the earth’s climate, as they have done in the past over long periods of time. However, calculations that only take these natural factors into account do not predict any significant warming of the Earth’s climate over the past century. Monotti implies that the positions of the Earth and the Sun relative to each other, as determined by cyclical changes over the short and long-term, could explain climate change. Put simply, long-term changes to the Earth’s orbit occur in the timeframe of 10,000-100,000 years. This is too long to explain the short-term changes to climate observed today. The Sun also undergoes its own short- and long-term cycles. Here again, the problem with this claim is that while long-term phenomena (thousands of years) do influence the climate over long periods of time, the changes to the climate that we are seeing are both drastic and very recent, i.e., +1°C between pre-industrial times and today. The 11-year solar cycle does indeed result in changes in the Sun’s energy output. However, these are modest (up to 0.15%) and cannot explain the magnitude of change observed. One overarching argument against changes in solar activity being responsible for climate change is that if this were the case, that is if the Sun’s energy output had increased, then all layers of the atmosphere should be warmer. Instead, however, measurements from different layers of the atmosphere show that the lower atmosphere or troposphere has gotten warmer, while the middle layer of the atmosphere or stratosphere has in fact gotten cooler[3](Figure 2). This is wholly consistent with a model in which CO2 mixes throughout the atmosphere but only traps heat closer to the Earth’s surface, due to the absorption of energy from the Earth’s surface. Figure 2 – Changing temperatures in the Earth’s atmosphere. Between 1986 and 2022, temperatures dropped in the higher levels of Earth’s atmosphere (starting at top left, blue shades); conversely, temperatures in those atmospheric layers closest to Earth have increased (bottom row, red shades). Image credit: Benjamin Santer/UCLA. Accessed from UCLA newsroom. Monotti also references volcanic activity and specifically the Hunga-Tonga Hunga underwater volcanic eruption of January 2022 as a source of climate change. Volcanoes can contribute to global warming in two ways, through CO2 emissions and, in cases of underwater eruptions, through release of water vapor into the atmosphere[4], which then traps heat. The Hunga-Tonga Hunga underwater volcanic eruption was indeed unprecedented in the amount of water vapor that was released into the atmosphere. However, this effect, while potentially marked, is temporary as the increased water vapor is expected to dissipate within a decade[5]."
https://science.feedback.org/review/clintel-group-inaccurately-represents-climate-science-declaration-no-climate-emergency-once-again/,Incorrect,"Clintel, The Epoch Times, Benoit Rittaud, Naveen Athrappully, Viv Forbes, Richard Lindzen, Patrick Moore, Ian Plimer, Guus Berkhout, Christopher Monckton, 2023-08-19",Global warming is just the end of the Little Ice Age; Warming is slower than climate models forecasted; Carbon dioxide is beneficial to Earth; Global warming is not intensifying or increasing the frequency of natural disasters,,"Incorrect:Observations show that global mean surface temperature has increased since 1850. Among other lines of evidence, climate models that have been skillful at simulating global mean surface temperature indicate that human activity–and, notably human emissions of carbon dioxide–is responsible for this increase, rather than the end of the Little Ice Age. Scientific evidence supports the finding that climate change influences various extreme weather events, which adversely impact plants and agriculture, contrary to the unsupported claims made in this letter and its coverage that suggest otherwise.","Scientists have investigated all potential causes of climate change and concluded that human activity is responsible for modern warming, not the end of the Little Ice Age. Climate change has adverse impacts on plants and agriculture, including through its influence on extreme weather events.","“The Little Ice Age ended as recently as 1850. Therefore, it is no surprise that we now are experiencing a period of warming.”; Warming is far slower than predicted”; “Climate models have many shortcomings…”; “CO2 is plant food, the basis of all life on Earth”; “There is no statistical evidence that global warming is intensifying hurricanes, floods, droughts and suchlike natural disasters, or making them more frequent.“",,"A letter published on August 14 by CLINTEL, a group that claims to have the support of “1,609 scientists and professionals”, repeats a series of familiar myths about climate science to arrive at its declaration that “there is no climate emergency”. The group has published similar claims about climate science in the same letter format in 2022 and 2019, both of which were previously analyzed by Climate Feedback, here and here. This year’s edition of the letter was covered by dozens of online blogs and news sites, including the Epoch Times, an outlet that has also previously published science misinformation. The letter first claims that “it is no surprise that we are now experiencing a period of warming” because the “Little Ice Age ended as recently as 1850”. The Little Ice Age refers to a period of slight cooling, typically defined as occurring from the mid-16th to mid-19th century that was particularly strongly expressed in the northern hemisphere (Fig. 1)[1]. Scientists have proposed a variety of explanations for the cause of the Little Ice Age, including reduced solar activity[2], variations in atmospheric circulation patterns[1], changes in North Atlantic ocean circulation and ice dynamics[3], large volcanic eruptions[4], and even human-driven land-use change triggered by European colonialism[5]. Figure 1. Reconstructions and observations of global temperature change over the last two millennia. The magnitude of temperature change during the Little Ice Age, denoted by the blue-shaded region of the plot, is far outweighed by current warming. Source: Climate Lab Book Here, the letter is implying that post-industrial warming resulted naturally from the end of this cool interval, which climate scientists say is not accurate. Climate scientists have parsed out the influence of human-caused and natural factors on global mean surface temperature, and have concluded that contemporary warming is due to human activity (Fig. 2)[6,7]. As Timothy Osborn, a climate scientist at the University of East Anglia, remarked in comments to Climate Feedback for a previous review of a similar claim, “[N]atural warming after the Little Ice Age was complete by the late 1800s. The warming from the late 1800s to the present is all due to human-caused climate change, because natural factors have changed little since then and even would have caused a slight cooling over the last 70 years rather than the warming we have observed” (Fig. 2). Figure 2. (left) Unprecedented rate of warming since 1850 and (right) observed (black) and simulated temperature change since 1850 with (brown) and without (green) human factors. Note that natural factors alone are insufficient to explain the unprecedented post-industrial rate of warming as documented in observations. Source: IPCC AR6 The letter goes on to claim that “warming is far slower than predicted” and that “[t]he world has warmed significantly less than predicted by IPCC [the Intergovernmental Panel on Climate Change] on the basis of modeled anthropogenic forcing”. However, the results from IPCC models shown in Fig. 2 indicate that the current suite of IPCC Sixth Assessment Report (AR6) models accurately captures the observed warming since 1850. Earlier climate models have also generally been skillful at simulating global mean surface temperature (Fig. 3)[8]. While some models have overestimated warming, others have underestimated it. As the authors of a 2019 paper[8]that explored the performance of projections by climate models over the last several decades put it, “We find no evidence that the climate models evaluated in this paper have systematically overestimated or underestimated warming over their projection period”. By suggesting that climate models have exclusively overestimated warming, the CLINTEL letter is engaging in cherry-picking–selectively reporting on only the results that match a desired outcome while excluding other pieces of relevant scientific evidence. Figure 3. Average of model-simulated temperature change from the IPCC’s first assessment report published in 1990 (black) against various temperature observations (colors). Source: Carbon Brief According to the letter, carbon dioxide (CO2), the greenhouse gas that is predominantly responsible for modern warming, is “plant food” that is both “favorable for nature” and “increas[es] the yield of crops worldwide”. However, scientists say that this claim oversimplifies the relationship between plants and CO2. “The benefit[s] of increasing CO2 concentrations for plant growth are increasingly being outweighed by the negative impacts, especially of global warming”, said Sara Vicca, a plant biologist and biogeochemist at the University of Antwerp, in comments to Climate Feedback for a previous article on the topic. “This is true for natural as well as agricultural ecosystems”. While satellite observations indicate that increasing levels of atmospheric CO2 have supported plant growth over the last few decades, these terrestrial (and marine) CO2 sinks do not remove all of the anthropogenic CO2 from the atmosphere. The uptake of carbon by terrestrial and marine plants together helps to slow the rate of warming. What’s leftover, however, causes climate change, which has a variety of adverse impacts on plants and agriculture. According to the latest IPCC report, human influence on climate has created physical conditions likely to increase the occurrence and severity of some extreme weather events (such as heavy precipitation, compound flooding, fire weather, and agricultural and ecological drought),[6]contrary to the letter’s claim that climate change “has not increased natural disasters”. Attribution scientists have even been able to identify the influence of climate change on individual extreme weather events in some cases. For example, scientists have found that the occurrence of the 2021 heatwave in the Pacific northwest region would have been “virtually impossible” without the existence of anthropogenic climate change.[9] These events, scientists say, put additional stress on plants and agriculture. “We are already seeing the first signs of a decline in the land CO2 sink and increasing extreme heatwaves and droughts seem to be a key reason behind this”, Vicca noted. One meta-analysis identified negative relationships between warming and the yields of maize, rice, wheat, and soy–four major agricultural crops.[10]Elevated levels of CO2 could also lower the nutritional value of rice, according to a 2016 study.[11] The author of the Epoch Times article purports that the CLINTEL letter contains the signatories of “over 1,600 scientists”. However, as in previous iterations of this letter, this claim is misleading because many of the letter’s 1,609 signatories are non-scientists and include people with the self-reported credentials of “retired teacher and manager of a small business”, “Senior Ship Designer”, and “Financial Advice Specialist”. Additionally, very few of the signatories who identify as scientists report credentials in climate science.References: 1 – Mann (2002). Little Ice Age. In: Encyclopedia of Global Environmental Change 2 – Mauquoy et al. (2002). Evidence from northwest European bogs shows ‘Little Ice Age’ climatic changes driven by variations in solar activity. The Holocene 3 – Lapointe et al. (2021). Little Ice Age abruptly triggered by intrusion of Atlantic waters into the Nordic Seas. Science Advances 4 – Miller et al. (2012). Abrupt onset of the Little Ice Age triggered by volcanism and sustained by sea-ice/ocean feedbacks. Geophysical Research Letters 5 – Koch et al. (2019). Earth system impacts of the European arrival and Great Dying in the Americas after 1492. Quaternary Science Reviews 6 – IPCC (2023). Summary: for Policymakers. In: Climate Change 2023: Synthesis Report. IPCC 7 – Tett et al. (2007). The impact of natural and anthropogenic forcings on climate and hydrology since 1550. Climate Dynamics 8 – Hausfather et al. (2020). Evaluating the performance of past climate model projections. Geophysical Research Letters 9 – Philip et al. (2022). Rapid attribution analysis of the extraordinary heat wave on the Pacific coast of the US and Canada in June 2021. Earth System Dynamics 10 – Moore et al. (2017). New science of climate change impacts on agriculture implies higher social cost of carbon. Nature Communications 11 – Zhu et al. (2016). Carbon dioxide (CO2) levels this century will alter the protein, micronutrients, and vitamin content of rice grains with potential health consequences for the poorest rice-dependent countries. Science Advances"
https://science.feedback.org/review/three-decades-chemtrail-haarp-geoengineering-conspiracy-theory-remains-popular-despite-lack-evidence-no-scientific-basis/,Incorrect,"Facebook, Facebook users, 2023-08-07",Global weather is controlled by secret geoengineering programs using chemtrails and ionosphere heating facilities.,,"Incorrect: Weather forms mainly in the troposphere and is driven by energy from the Sun. Research facilities like HAARP only influence a small area of the ionosphere directly above them, which is tens to hundreds of kilometers above where weather forms and occurs.  Unsupported: There is no evidence for the existence of chemtrails nor is there evidence for the saturation of Earth’s atmosphere with any substances from chemtrails. The energy that research facilities like HAARP transmit to the atmosphere is billions of times smaller than the energy needed to power most weather systems such as mid-latitude cyclones. ","While it is possible to change the Earth’s long-term climate through elevated atmospheric greenhouse gases, humans lack the scientific, technological, and logistical capabilities to control short-term weather events at the global scale. There is no evidence for the existence of chemtrails, nor for their claimed impact on global atmospheric chemical composition and physical properties. The Sun drives weather and sends far more energy to Earth than ionosphere heating facilities like HAARP can transmit. These facilities are radio transmitters that can only excite small areas of the ionosphere directly above them, whereas weather occurs primarily in the troposphere and all over the planet.",Global weather is controlled by secret geoengineering programs using chemtrails and ionosphere heating facilities. There is no natural weather at this point.,"1 – IPCC (2021) Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change 2 – Shearer et al. (2016) Quantifying expert consensus against the existence of a secret, large-scale atmospheric spraying program. Environmental Research Letters 3 – Mironova et al. (2015) Energetic particle influence on the Earth’s atmosphere. Space Science Reviews 4 – Li et al. (2017) Analysis of ionospheric disturbances associated with powerful cyclones in East Asia and North America. Journal of Atmospheric and Solar-Terrestrial Physics 5 – Abshaev et al. (2022) Rain Enhancement Through Cloud Seeding. Unconventional Water Resources","Introduction Can humans control the weather on a global scale as periodically claimed by viral social media posts? Let’s review the basics. Weather is short-term atmospheric conditions, while climate is long-term atmospheric trends. Changing the climate is a bit like water eroding rocks in a river; it’s possible but requires long-term effort. By increasing atmospheric greenhouse gas concentrations over many decades, human activity has changed Earth’s climate and increased average global temperatures[1]. However, changing daily weather on demand would be like carving and cutting through rocks with a high-power waterjet. If it’s possible, it would require a huge amount of energy to pull off. Weather is a complex, dynamic, and high-energy system driven by the 430 quintillion joules (430 followed by 18 zeros) of energy the Sun sends to Earth every hour. That’s more energy in one hour than all the energy humans can produce and use in a year. Using the recent film Oppenheimer for reference, it’s equivalent to nearly 7 million Hiroshima atomic bombs (blast yield of 63 trillion joules) exploding every hour to keep weather functioning as we know it. With such stark difference in scales between human energy production and the energy pools and fluxes involved in the global weather system, it’s clear that controlling daily weather is beyond human capabilities. Still, one popular geoengineering conspiracy claims that we do already, and it has persisted from the early days of the internet to now flourish in the age of social media: the chemtrail-HAARP conspiracy theory. In a recent example from 7 Aug. 2023, a video posted on Facebook presents this theory as part of a global geoengineering conspiracy involving a secret large-scale atmospheric program (SLAP). It describes the saturation of the atmosphere with chemical and metal particulates from airplane chemtrails which has supposedly enabled weather manipulation using a network of ionosphere heating facilities, such as HAARP. Having been viewed over 500 thousand times, this is just one of several social media posts on this topic that have become viral in recent months, such as this, this, and this. The ultimate goal, according to some proponents, is to influence global geopolitics through targeted weather events. For a conspiracy of this scale to be plausible, many logistical, socioeconomic, governmental, and legal challenges would need to be first addressed. But by exploring only some of the physical aspects mentioned in this clip, this claim review demonstrates the insurmountable scientific challenges already invalidating the chemtrail-HAARP conspiracy theory. No evidence for chemtrails and their supposed effects The unidentified narrator in the clip begins by explaining that chemtrails are “what we see happening in the sky, this is weather modification on a global scale”. As a popular anchor point in geoengineering conspiracy theories since the 1990’s, the concept of chemtrails is inspired by a very real phenomenon called contrails. Contrails, or condensation trails, occur when water vapor and soot particulates from airplane exhaust freeze mid-air and form ice crystals. These are the long white lines crisscrossing the sky after planes have flown by. Differences in the level of humidity at the time and location of the airplane’s flight determines the visibility and longevity of its contrails, which is why not every plane you see will have them. Figure 1 – Left: Factors in the formation of contrails. The moisture and temperature at the time and location of the flight determines the visibility and persistence of a contrail. Conspiracy theorists who fail to understand the physical origin of this variability use it as evidence of an ongoing secret chemtrail program (source). Right: Examples of persistent contrails that visibly appear different despite occurring in the same location. Scenarios like this are also used as proof of chemtrails, but in reality they appear different because they formed at slightly different times and at different altitudes with different moisture and temperature conditions (photo: Ron Smith). Chemtrails, on the other hand, have never been demonstrated in any scientific study. Chemtrail conspiracy theorists generally claim that there are secret programs, whether run by government, military, or other, that use airplanes to spread toxic chemicals throughout the atmosphere. According to the theory, the cloud-like streaks in the sky that airplanes leave behind them are not just contrails, they can also be visible proof of chemtrails. But without in-situ sampling, in-depth investigations, or scientific studies proving chemtrails exist, distinguishing them from contrails remains a matter of faith. Aside from being used to enable geoengineering and weather control, chemtrails are also believed to be used as a means of mass sterilization, mass poisoning, and even mind control on targeted populations. According to the narrator, this secret large-scale atmospheric program (SLAP) starts with spreading chemtrails to achieve a global “…saturation of the atmosphere with various chemical and metal particulates” which “…ionizes the atmosphere, makes the atmosphere more conductive”. But in a 2016 study which surveyed of some of the world’s top atmosphere experts, consisting of atmospheric chemists with expertise in condensation trails and geochemists working on atmospheric deposition of dust and pollution, virtually every single respondent did not believe there is any scientific evidence for a SLAP using chemtrails[2]. Even when assessing data that conspiracy theorists claim is proof of chemtrails, such as elevated concentrations of specific elements in soils, sediments, and water bodies in remote locations, the overwhelming majority of the respondents stated that there are simpler and better supported explanations. In addition, there are no scientific studies nor any existing data confirming elevated global atmospheric, soil, sediment, or water concentrations of the various chemicals that chemtrails are claimed to spread. There is also no evidence of a more conductive atmosphere over the last two to three decades, and no scientific basis for the possibility of human activities to “ionize the atmosphere”. Atmospheric ionization, especially at the altitudes where weather occurs, is instead a result of the Sun’s radiation (extreme ultraviolet and X-rays) and the atmosphere being bombarded with energetic precipitation particles such as aural electrons, radiation belt electrons, solar protons, and galactic cosmic rays[3]. These outstanding issues do not support the claims made in this clip, which also fails to provide any references to data or studies that would support the claims made. Ionosphere heaters do not influence the weather The second component of the chemtrail-HAARP conspiracy theory involves the use of radio wave transmitters, specifically ionosphere heating facilities which are designed to study plasma turbulence and the behavior of the ionosphere and upper atmosphere. The High-frequency Active Auroral Research Program(HAARP) in Alaska, USA is the most famous such facility, especially for being a popular subject of conspiracy theories since its inception in 1990. In addition to weather modification events, HAARP has been also been blamed for recent disaster events like the 2023 Hawaii wildfires and Turkey–Syria earthquake. Originally a joint research facility of the United States Air Force and the University of Alaska-Fairbanks, HAARP has been operated exclusively by the university since 2015. The narrator of the clip mentions HAARP in Alaska as being just one HAARP facility of “at least 18 around the globe, possibly with 3 more being built in Antarctica right now” as part of the SLAP. But regardless of how many facilities do or do not exist in reality, this theory overlooks several conceptual problems. Ionosphere heaters are radio transmitters and therefore only manipulate electrical charges and currents. As the storms in the ionosphere caused by the Sun do not interfere with surface weather, the far less powerful experiments of facilities like HAARP are a non-factor. HAARP can transmit up to 3.6 megawatts into the upper atmosphere and ionosphere with a transmission efficiency of only 45%. Even at 100% efficiency, HAARP’s transmission capability is negligible considering the 1.5 million megawatts of kinetic energy and 6 hundred million megawatts in latent energy produced by a single hurricane per day. Furthermore, HAARP’s high-frequency signal reaches the ionosphere at around 14 milliwatts per square meter (at 200 km altitude based on this example), almost a hundred thousand times less intense than the Sun’s natural electromagnetic radiation constantly hitting Earth (known as the solar constant, roughly 1.361 kilowatts per square meter). These are some of the reasons why this geoengineering conspiracy theory is baseless: ionosphere heating facilities like HAARP simply aren’t powerful enough to alter the atmosphere significantly and influence the weather. Almost all weather occurs in the troposphere where 75% of all the air in the atmosphere and almost all of the cloud and rain-forming water vapor are found. There is no known link between ionosphere heating experiments and weather behavior in the troposphere at the site of the ionosphere heating facility, let alone at the global scale. These facilities were intentionally designed for, and therefore technologically limited to, interacting with the electrons and ionized atoms and molecules that make up the ionosphere. They are not able to interact with weather related properties at lower altitudes, such as water in clouds in the troposphere. Spanning from about 80 kilometers above the surface of the Earth to the edge of space, the ionosphere does not overlap with the range of the troposphere (between 6 km at the poles to 20 km at the equator) according to NASA and NOAA. Figure 2 – The layered structure of the Earth’s atmosphere, from the surface to outer space. The ionosphere spans from the mesosphere to the exosphere (left panel source; right panel source). Even if we assume there are elevated “chemical and metal particulates” in the atmosphere due to chemtrails and that the atmosphere has been “ionized” by humans, there is still no explanation for how this will help ionosphere heating facilities affect global weather. While extreme weather in the troposphere can influence the ionosphere[4], there is no scientific explanation for how the transmissions from these facilities could cause weather events under this hypothetical “more conductive” atmosphere. And then, even if we assume there is a scientific explanation with empirical support, the energy required to counteract ongoing natural weather phenomena normally driven by the Sun’s non-stop solar energy would be enormous and beyond our capabilities. Afterall, ionosphere heating facilities have limited and well-known energy transmission capacities, and they can only heat up a tiny space directly above them compared to the planetary scale of the atmosphere. Again, even with 18 or more locations, there is no explanation for how these small experimental plots can expand to control weather across the Earth’s entire troposphere tens to hundreds of kilometers below. Despite the narrator’s unsupported claim that “the entire weather system globally is virtually being thwarted”, this geoengineering conspiracy theory relies on too many conceptual and theoretical leaps to hold any water. So, can we control the weather? It is a fair scientific and ethical question that deserves asking. In fact, with all the gargantuan challenges delegitimizing the chemtrail-HAARP conspiracy theory of global weather control, there is already a widely known example of attempted local weather modification. You may remember seeing Chinese military personnel operating cannons aimed at the sky during the 2008 Beijing Summer Olympics. They were on-guard, ready to perform cloud-seeding. Also known as “blueskying”, cloud-seeding is the introduction of small particles of, for example, silver iodide or dry ice to clouds to promote rain or snow formation by providing a surface for water droplets to collect on or ice crystals to freeze around. It is no guarantee of precipitation, but it’s interesting enough for the Chinese government to spend billions of dollars in cloud-seeding research to ensure agricultural regions receive rain when needed and large public events are sunny and cloudless. This approach was apparently used successfully to pre-rain the Beijing sky and reduce air pollution before the 100th anniversary celebrations of the Chinese Communist Party in 2021. In the United States, the US Bureau of Reclamation recently committed over two million dollars in 2023 to combat drought in the Upper Colorado River Basin using cloud-seeding. But there’s a big difference from cloud-seeding in one single location of the world to give clouds a microphysical nudge in the right direction towards precipitation, and being able to cause or prevent storms, hurricanes, blizzards, floods, or droughts anywhere in the world and at any time. Even the effectiveness of cloud-seeding is still uncertain[5] with several potential unintended consequences, but at least it is a legitimate weather modification theory with a reasonable scientific basis for experimentation and evaluation. Controlling weather at the global scale, on the other hand, is currently far beyond human scientific, technological, and logistical capabilities. The chemtrail-HAARP geoengineering conspiracy theory is guilty of overlooking these limitations, making multiple unsupported assumptions, and ignoring the Sagan standard “extraordinary claims require extraordinary evidence”."
https://science.feedback.org/review/magnetic-poles-reversals-not-cataclysmic-events-adam-and-eve-theory-jimmy-corsetti-joe-rogan-podcast/,Incorrect,"The Joe Rogan Experience, TikTok, Spotify, Joe Rogan, Jimmy Corsetti, 2023-01-18","Magnetic poles reversals involve the Earth flipping vertically and momentarily stopping its rotation, causing cataclysmic events during 6 days.",,Unsupported: There is no evidence that magnetic reversals have any impact on climate nor is there scientific basis for the claim that the planet flips on itself within six days.  Misunderstanding of science: Speculation on the imminent possibility of the next magnetic poles' reversal happening is based on confusing averages with a normal. Scientists estimate that the probability of the Earth’s magnetic field reversing within the next 20 000 years is extremely low.  ,"Magnetic poles reversals do occur, but don’t involve the earth’s poles physically changing positions. The liquid core of the planet moves, generating variations of the magnetic field and occasionally, magnetic poles shift. There is no evidence that magnetic poles' reversal have had any influence on climate in the Earth’s history or generated the kind of extreme weather events claimed, by contrast carbon dioxide concentration has been shown to influence global climate in the past and present.","Shifts in the planet’s magnetic poles involve the earth doing a 90° flip, with the planet remaining still for 6 days. During this short period, cataclysmic events happen, involving heat, wind, floods, and climate change.","[1] Singer et al. (2019). Synchronizing volcanic, sedimentary, and ice core records of Earth’s last magnetic polarity reversal. Science Advances. [2] Brown et al. (2018). Earth’s magnetic field is probably not reversing. Proceedings of the National Academy of Sciences. [3] Buffet et al. (2018). A Probabilistic Assessment of the Next Geomagnetic Reversal. Geophysical Research Letters.","The planet’s magnetic field acts as a shield surrounding the Earth, protecting its surface from solar radiations. It is generated within the Earth’s liquid core, and varies according to the movement of molten iron present in it. The core creates currents of electricity featuring a direction, giving us the north and south, and an intensity, which is strongest near the poles. Many variations of the Earth’s magnetic field in Earth’s history have been recorded in solidified lava or sediments, from displacement of the magnetic poles to full magnetic poles swap. In a recent podcast episode, Comedian and Ultimate Fighting Championship commentator Joe Rogan and YouTuber Jimmy Corsetti talked about the so-called “Adam and Eve” theory. Even though this theory has no support in science, as we will show below, Corsetti and Rogan discussed it as if it were credible. Corsetti appears to believe that when magnetic poles reverse, the Earth flips over itself and stops rotating for six days. Corsetti also claimed that the next reversal should happen in a very near future, and that it would be cataclysmic. A clip from this interview was viewed over twenty millions times on TikTok, and several other clips were widely shared on social media. Magnetic poles reversals are not a “planet flip” The “Adam and Eve” theory laid out in the interview suggests that magnetic poles’ reversal includes the Earth doing a “flip”, involving North and South poles physically changing positions. In reality, no scientific evidence indicates that the Earth ever performed such flips. This claim is extremely implausible, as there is hardly anything that could flip the Earth in such a way, apart from a collision with planets or other astronomical bodies. According to Corsetti’s explanation, magnetic poles reversals would take place over a six days period. However, measurements show that the time taken for a magnetic poles’ reversal is on the order of thousands of years. Geologists found that the most recent field reversal, some 770,000 years ago, took at least 22,000 years to complete, for instance[1]. A duration of six days for the reversal of the Earth’s magnetic field is not close to any scientific observation. Corsetti also claimed that, during these six days, the planet would stop rotating, but he doesn’t explain where a force strong enough to stop the Earth’s rotation would come from. “A magnetic reversal causes a change in electric currents within the liquid metal core. These currents can alter the forces inside the liquid metal core, but this cannot stop the rotation of the Earth” explains University of California Berkeley professor Bruce Buffett in an email to Science Feedback. “As an analogy, you can’t literally pull yourself up by your bootstraps.” Forecasting the next magnetic poles’ reversal Jimmy Corsetti claims that the next magnetic pole shift is likely to happen soon “as we are 200000 years overdue”. The last reversal took place 780000 years ago, according to NASA scientist Alan Buis’ article on magnetic fields. On average, the time interval between reversals is 300 000 years, but it varies greatly. Yet Corsetti’s claim misunderstands this average time between reversals with a regular pattern. Past magnetic fields can be recorded in rocks or sediments, and many were analyzed: they show a large variability of the intervals between reversals of polarity measured in sediments. Figure 1 shows that polarity reversals haven’t followed a regular pattern. Short intervals have a duration of an order of tens of thousands of years, while exceptionally long intervals with a single polarity last 10 million years and are called superchrons. For instance, the Cretaceous Normal superchron lasted approximately 40 million years. So there is no indication that, because more than 300 000 years passed since the last reversal, the next one could be expected anytime soon. Figure 1 – Geomagnetic polarity over the past 169 million years, trailing off into the Jurassic Quiet Zone. Dark areas denote periods of normal polarity, light areas denote reverse polarity. Credit: Public domain. Source : NASA Global Climate Change. Scientists have looked at the probability of magnetic pole shifts occurring in the near future. Records show that the geomagnetic fields’ strength decreases before reversal events, and such a decreasing trend has indeed been observed over the past centuries. So it is legitimate to wonder whether a reversal is likely to happen soon. However, a few centuries is still a very short period of time on the scale of such variations. A scientific study found that the Earth “is not in an early stage for a reversal”[2]. Another scientist not involved in this study also agrees: “My own theoretical estimate, based on geological estimates of past behavior, is that the chance of a magnetic reversal in the next 20,000 years is only about 2%” adds Professor Bruce Buffett. Climate change and magnetic fields According to the claim, extreme weather events such as the sun staying in the same spot causing “heating like we’ve never experienced” or “1000 miles per hour (ca. 1,609 kilometers per hour)” winds would happen as a result of magnetic poles’ reversal. In reality, the only significant risk known to impact society is that a reversal temporarily weakens the magnetic shield protecting us from bursts of radiations from the sun, called solar flares. Solar flares can disrupt satellite communications, but theyare not the kind of cataclysmic events described by Corsetti. “There is no evidence that magnetic reversals have any impact on climate” emphasizes UC Berkeley professor Bruce Buffett. “We might be more impacted by solar flares, but there is no evidence that this alters climate. As far as I know, there is no proposed mechanism that would allow this to happen.” Scientists have examined this question in numerous studies, but the results haven’t demonstrated a causal link between magnetic poles reversals and climate. As reminded by NASA scientist Alan Buis on the agency’s website, “electromagnetic currents exist within Earth’s upper atmosphere. […] In the long run, the energy that governs Earth’s upper atmosphere is about 100,000 times less than the amount of energy driving the climate system at Earth’s surface. There is simply not enough energy aloft to have an influence on climate down where we live.” The unsupported “Adam and Eve” theory, along with Corsetti’s speculations on an imminent reversal, leads Joe Rogan to claim that climate change is of lesser importance. Rogan claimed climate change is “this narrative that just gets repeated over and over and over and this fear mongering and everyone gets freaked out”. He then compared it to the “Adam and Eve” theory, “If the f***ing magnetic poles might shift […] we might have bigger problems.” As explained above, both claims of impact on climate and of a potential reversal occurring soon are unsupported and go against available evidence. When comparing risks, Rogan doesn’t appear to be aware of scientists’ very high confidence in the fact that reaching a global warming of 1.5 °C above pre-industrial levels in the near-term “would cause unavoidable increases in multiple climate hazards and present multiple risks to ecosystems and humans”, as noted by the International Panel on Climate Change (IPCC). There are 127 key risks associated with climate change identified by the IPCC, and their impacts in the mid and long term “are up to multiple times higher than currently observed”. So a magnetic poles reversal is far from being a more important risk than climate change, contrary to Rogan’s belief. Scientists’ Feedback: Bruce Buffett Professor, University of California, Berkeley: A magnetic reversal causes a change in electric currents within the liquid metal core. These currents can alter the forces inside the liquid metal core, but this cannot stop the rotation of the Earth. As an analogy, you can’t literally pull yourself up by your bootstraps. There is no evidence that magnetic reversals have any impact on climate. The overall strength of the magnetic field decreases during a reversal. This allows charged particles from the Sun (known as solar wind) to penetrate deeper into the atmosphere. We might be more impacted by solar flares, but there is no evidence that this alters climate. As far as I know, there is no proposed mechanism that would allow this to happen. Reversals occur at irregular intervals in the geological past, based on the magnetization of igneous rocks. If we average over the past few million years, the typical recurrence interval is about 250,000 to 300,000 years. The last one was 780,000 years ago, so you might argue we are overdue. In fact, there have been recent suggestions that we are entering the next geomagnetic reversal. My own theoretical estimate, based on geological estimates of past behavior, is that the chance of a magnetic reversal in the next 20,000 years is only about 2%[3]. A reversal lasting only 7 days would be difficult to detect in the geological record, but this is not realistic. A more typical estimate for the duration of a reversal is in excess of 10,000 years (depending a little on how you define a reversal; is it the time to flip the orientation of the magnetic field or the time required to flip the orientation and bring the amplitude back up to the average value?). Flipping the magnetic field orientation to the reversed state and back to the original state in 7 days would require absurdly large fluid velocities in the liquid metal core. Let’s suppose that the Earth stopped rotating. The centrifugal acceleration associated with rotation would disappear. This acceleration is presently responsible for the equatorial bulge of the solid part of the planet, as well as the oceans. The solid part of the Earth would have an abrupt elastic response of several kilometers when rotation stopped. Similarly, the oceans would respond on timescales of a few days. I would expect to see kilometers of sea level change as the solid earth and ocean adjust by different amounts over short times. It would be hard to miss this change."
https://science.feedback.org/review/headline-temperatures-on-earth-are-increasing-and-the-rise-is-drastically-outpacing-previous-natural-changes-in-the-planets-climate/,Inaccurate,"Media Research Center, Ian Plimer, 2023-05-02","“We have been cooling down for the past 4000 years”; the Earth has cooled since the ‘medieval warming’, “It’s all about when you start the measurements”",,"Factually inaccurate: Earth’s surface has not been cooling in recent times - both global average and Greenland temperatures have rapidly increased since the beginning of the industrial era.  Misleading: The most recent temperature datapoint that the claim references corresponds to 1855, which is misleading since warming caused by humans occurred mostly after this time.","Temperature data indicate that global temperatures are already higher than at any other period in the past several thousand years. Multiple independent lines of evidence indicate that the Earth is currently warming at a rate that is much faster than past changes in climate. Increasing atmospheric carbon dioxide levels due to human activities are a key driver of this change, as has been consistently shown by a consensus of scientific data.","“We have been cooling down for the past 4000 years”; the Earth has cooled since the ‘medieval warming’, “It’s all about when you start the measurements”","1 – Alley (2000) The Younger Dryas cold interval as viewed from Central Greenland Quaternary Science Reviews 2 – Hörhold (2023) Modern temperatures in central–north Greenland warmest in past millennium Nature 3 – Wilson (2016) Last millennium northern hemisphere summer temperatures from tree rings: Part I: The long term context Quaternary Science Reviews 4 – IPCC (2021) Climate change widespread, rapid, and intensifying – IPCC 5 – Cuffey and Clow (1997) Temperature, accumulation, and ice sheet elevation in central Greenland through the last deglacial transition Journal of Geophysical Research 6 – More et al. (2017) Global risk of deadly heat Nature Climate Change 7 – Im et al. (2017) Deadly heat waves projected in the densely populated agricultural regions of South Asia Science Advances","Information about Earth’s past climate can provide insights for the trends we are currently experiencing. Historical temperature conditions can be reconstructed from archives such as ice cores and tree rings that contain proxies for temperature. Although records exist of measured temperatures that date back to 1659 (Figure 1), direct records predating the 1880s are too sparse for the purposes of climate studies at a global scale, hence the need to rely on proxies. Figure 1 – Mean temperature anomalies for each full year in the Central England Temperature series against 1961-1990 climatology. While these data also show temperature increases since the industrial era, they are too sparse for climate studies at a global scale. Source: HadCET (2023) Ian Plimer, a former mining geologist who has previously made unsupported claims about climate change, recently claimed “we have been cooling down for about the past 4000 years”, implying that this somehow contradicted what scientists know about recent global warming. In the video, Plimer falsely claims that there has been no change in temperature over the past 38 years, in direct contradiction to available data (see Figure 2). Plimer also claims that the global temperature has been cooling since the “medieval warming”, which he can only conclude by ignoring any data after the 1850s; this claim has previously been debunked on Science Feedback. Figure 3 shows that current temperature increase is happening at higher rates than past changes in climate over the last 2,000 years. Figure 2 – Global temperature estimates compiled by Berkeley Earth Figure 3 – Global Warming/cooling rates averaged across 51 years and based on paleoclimate records. Modern thermometer records shown in black. Source: University of Bern Plimer points to temperature data over almost 10,000 years taken from one ice core extracted from the Greenland Ice Sheet, Greenland Ice Sheet Project 2 (GISP2), citing a 2000 paper[1] by Richard Alley, Professor of Geosciences at Pennsylvania State University. However, this dataset does not capture the past 170 years, which is the period after which the Earth began warming due to human activities. In addition, since the data dates back to the 1990s and was extracted from just one ice core using assumptions that are now questioned and analysis optimized for studies of tens of thousands of years rather than the past two centuries, it is not a suitable reference for discussions of current climate change and more recent data extracted with more modern analysis techniques exist. “The curve misses the point as it is not showing the context of recent global warming,” Anders Svensson, Associate Professor in Physics of Ice, Climate and Earth at the University of Copenhagen told Science Feedback, pointing out that the time scale shows years before 1950 CE and that the most recent point is 1855. The current rising temperatures due to human activities that are causing concern mostly occurred after 1855. In response to Plimer’s emphasis on the importance of timeframes temperature comparisons are made within, Maria Hörhold, a senior researcher in the Department for Glaciology at the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research pointed out that looking at a longer time frame would be more useful for showing the seesaw pattern of temperatures in glacial and interglacial periods. In her own study[2] on more recent analysis to extract temperature data from Greenland ice cores, she and her colleagues also point out that their data show temperatures cooling down until the industrial era hit in the nineteenth century. It is at this point that human activities led to global warming. In addition this is not on a par with the previous rate of cooling but at a much higher rate, as shown in Figure 4 below. NASA’s Earth Observatory website quantifies current warming at 10 times faster than previous warming after the last ice age. “The natural system has cooling and warming”, she told Science Feedback. “That is not under debate, no-one is arguing against that”. However, the fact that climate changed naturally in the past in no way invalidates scientific understanding that current emissions of greenhouse gases by human activities are also causing the global climate to change now. Figure 4 – The graphs show temperatures for Greenland (NGT, the North Greenland Traverse) taken from ice cores, compared with temperatures from the broader Arctic region (north of 60°N) and measured meltwater run off. It shows how recent warming due to human activities drastically outpaces the previous natural cooling trend. Source: Hörhold et al. (2023)[2] Temperature data in the recent Nature study[2] by Hörhold and colleagues cover the period 1000-2011 AD and identify a clear warming trend, with temperatures over 2001-2011 exceeding temperatures over any other period in the past thousand years. Temperature reconstructed from tree rings show the same trend[3], and an estimated warming of approximately 1.1°C since the industrial era was reported[4] in 2021 by the Intergovernmental Panel on Climate Change (IPCC) – an organization that synthesizes the best available research carried out by scientists globally. Data processing challenges There are numerous challenges in extracting reliable temperature data from ice cores as described at length in this article by Carbon Brief. One of the main issues is the noise, that is, fluctuations in the data that make it harder to identify a trend. This can be local due to wind blowing snow around the surface of the ground before it is compacted into ice, or it can result from natural fluctuations in weather. There are now recognized ways of dealing with this noise for modern day studies that can extract more reliable temperature data that holds for the region from which the ice cores are taken. One approach, as used by Hörhold and colleagues to amplify the signal of any trend in the temperature data over the noise, is to combine the data from several ice cores taken from different points. “In the data from Cuffey and Clow[5] used in the Younger Dryas paper[1], [that is, the 2000 paper that the graph Plimer cites is taken from] there is some smoothing applied, and, the data shown were optimized to capture the change from ice age to today, not to capture shorter-lived changes more recently,” Alley told Science Feedback, flagging the limitations of the data when looking at shorter time frames. He also notes that despite many reconstructions that have been made for more recent times, this particular misinterpretation “keeps coming back”. “So, it [the dataset Plimer cites] is not global”, he adds. “It is smoothed in a way that is not best for the purpose of looking at recent changes, it is not the right data set if you are concentrating on recent changes, and it is no longer the most up-to-date data set. Careful scholars simply would not be making any interpretation of recent temperatures based on this old publication.” As Alley told Andrew Revkin for an article in the New York Times 13 years ago, “using GISP2 data to argue against global warming is, well, stupid, or misguided, or misled, or something, but surely not scientifically sensible.” Current human activities are causing global warming Alley also points out that over the course of Earth’s long history spanning hundreds of millions of years, there have been many periods that are hotter than now, so hot that large regions would have been uninhabitable to unprotected humans. “The high temperatures in those past times were primarily caused by high CO2 levels”, said Alley. “Those were caused naturally, and the warming occurred at much slower rates than what we’re doing. The current rise is not natural, but caused by us.” Hörhold also highlights how temperature variations correlate with CO2 concentrations. Historic CO2 concentrations can be measured from ice cores too and naturally vary from 280-320 ppm. Looking at global CO2 levels for the past year for instance at CO2.Earth, reveals concentrations around 420 ppm. “Much higher than this natural variation,” adds Hörhold. On account of these increased CO2 concentrations, the historical correlation with temperature, and the increased temperatures in modern day measurements, scientists no longer doubt that we are in a period of global warming due to human activities that emit greenhouse gases like CO2. Conclusion: In summary, Plimer cherry-picks one old dataset that is a proxy for the temperature at a single point in Greenland to falsely imply that the Earth as a whole has cooled since the ‘medieval warming’ or the past 4000 years. When scientists reconstruct Earth’s surface temperature, they show that global temperatures have warmed rapidly over the past century, largely exceeding the slow and local temperature variations during the ‘medieval warming’ or the little ice age. Scientists’ Feedback: Richard Alley Professor, PennState University: Scientific studies have shown that, under strong human-caused warming, we could approach or reach temperatures in some places this century that would be fatal for unprotected humans—someone sitting naked in the shade in the wind drinking water would still die of heat stroke. Well before that, impacts of heat likely would drive many people away by stressing them and their crops and farm animals[6,7]. I frequently meet people who say “Climate has always changed naturally, so we should not worry about people changing climate.” I have never met someone who said, “Fires have always occurred naturally, so we should not worry about arson.” I have never met someone who said, “People have always died, so we should not worry about murder.” Climate has always changed, which proves climate is changeable. Climate change has always affected living things, which shows that climate change is important. Climate has changed for many reasons, but especially because of changing CO2, which focuses special attention on our release of CO2 to the atmosphere from fossil-fuel burning and other activities. When authoritative bodies look at the history of climate and use that knowledge to help inform understanding of possible futures, they find that releasing more CO2 to the atmosphere will change the climate in many ways, and these will overall make life harder for humans. Very strong scholarship shows that using this knowledge effectively can help the economy as well as the environment."
https://science.feedback.org/review/antarctic-ice-coverage-not-increasing-record-levels-nor-continent-getting-colder-contrary-to-curry-easterbrook-cfact-movie/,Inaccurate,"CFACT, Instagram, Don Easterbrook, Judith Curry, 2023-04-16",Antarctic sea-ice extent is increasing to record levels. Antarctica is getting colder; its sea ice and ice cap are not melting,,"Cherry-picking: Antarctic sea-ice extent reached a record high in 2014, but that was not the sign of a long term trend of expansion since a precipitous decline followed, with the sea ice extent reaching its lowest value in 40 years.Factually Inaccurate: The consensus of scientific evidence shows that the average temperature over the Antarctic has not been getting colder. Some of the world’s fastest warming is observed in regions of the continent.","Despite a period of slight growth between 1979 and 2014, Antarctic sea ice cover is not increasing to record levels. The trend reversed in 2014 and ice cover started to decrease vigorously. Many long-term measurements from Antarctic research stations show no significant warming or cooling trends over the whole continent, but parts of the continent are among the regions experiencing the fastest warming in the world, and the ice cap is losing mass.","We’re seeing record set for antarctic sea ice extent. Climate models predict that antarctic should be losing sea ice, and it’s exactly the opposite of what’s happening. The antarctic ice cap is not melting, the average annual temperature there is 58 degrees below 0°. There’s not melting going on in the first place, it’s actually growing.  The sea ice is at record high because it’s getting colder",,"Science has shown consistently that adding CO2 to the atmosphere is changing the climate in various ways, including raising the surface temperature of the oceans and atmosphere. As a consequence, scientists anticipate that polar sea ice would decline. This has been observed in the Arctic, which shows a 40% reduction in minimum sea-ice extent over the past 44 years[1]. However, the situation in the Antarctic is more complex because the continent is more isolated from the influence of global warming as explained in this article. This complexity has been seized by climate contrarians to try and cast doubt on the scientific understanding of the impacts of climate change. The claims that the Antarctic sea ice cover is increasing and that the average temperatures in the continent are getting colder are taken from the 2016 film Climate Hustle, produced by CFACT, an organization part of the climate change countermovement according to a climate change polarization study[2]. A short video snippet from this film has been shared on social media. One post on Instagram received 30 000 likes over a single week in April 2023. Former climatologist Judith Curry, who called into question the fact that humans are the dominant cause of recent climate change in Congressional Testimony, first claims that “Antarctica sea ice extent is increasing to record levels”. Sea ice extent refers to the cumulative area of all ocean surfaces where water is covered with ice. On the other hand, the terms ice cap and ice sheet refer to ice covering terrain such as land or bedrock. In order to understand the trends in sea ice extent, scientists study its area in February and September, respectively the periods in which the ice cover retreats and peaks. The most accurate data available to detect trends in Antarctic ice coverage are satellite observations, with records starting in the late 1970s. A study compiling 40 years of such records published in 2021 by NASA Research Scientist Claire L. Parkinson found that the Antarctic sea ice cover has been growing very slightly on average until 2014, at which point it started to decrease vigorously at rates “far exceeding the more widely publicized decay rates experienced in the Arctic”[3] (see Figure 1 below). So despite a period of growth between 1979 and 2014, the data shows clearly that the Antarctic sea ice cover is not increasing to “record levels”. Figure 1 –Time series of monthly mean Antarctic Sea ice extent anomalies for all February months from 1979 to 2023. The anomalies are expressed as a percentage of the February average for the period 1991-2020. Source In the video snippet, Judith Curry also claims that “climate models predict that the Antarctic should be losing sea ice, and it’s exactly the opposite of what’s happening”. This statement comprises correct and incorrect claims. Overall, climate models did predict a decrease in Antarctic sea-ice cover[4]. For instance, scientists ran the HadCM3 model in 2002 to simulate past sea ice extent between 1970 and 1999. The model simulated Antarctic Sea ice extent decreasing to 12.5 million km2 in 1999 while observations in 1999 showed sea ice extent grew over 14 million km2. Authors of the study attribute the difference with observations to the scarcity of data on the Southern Ocean around Antarctica. By comparison, the model accurately simulated a 2.5% decrease per decade trend in average Arctic sea ice extent for 1970–1999, which is very similar to observations[5]. Nonetheless, current observed trends do not totally contradict these projections, since a shift occurred from a period of sea-ice growth (1979-2014) to a period of sea-ice decline (2014-2022). Moreover, one purpose of models is for scientists to test their understanding of complex issues, and the Antarctic ice coverage is one of those. “Antarctic sea ice has puzzled modelers for a while. They expected a decrease in sea ice, not a slight increase; and the abrupt change in 2016 was not expected.” comments Eric Rignot, Earth System Science Professor and Chair at UC Irvine, in an email to Science Feedback. Even though the individual elements driving sea ice evolutions are fairly understood, the case for modeling the Antarctic sea ice coverage is especially difficult because of their interactions. “Complex feedbacks involving not only the sea ice and its snow cover but also the ocean, atmosphere and ice sheet (as well as biogeochemical processes)” are the main causes, according to scientist Kyle Clem’s article on Antarctica sea ice predictions[6]. Yet, this subject is not a blind spot in scientific research as, for more than 20 years, numerous scientists have examined reasons for sea ice coverage increase during the 1979-2014 period, formulating different hypotheses[7-10]. In any case, the complexity in modeling Antarctic sea ice extent isn’t enough for undermining all climate models’ accuracy. Indeed, climate models can’t forecast every variable perfectly, but they still skilfully forecasted the evolution of global temperatures. After testing the most prominent climate models predicting global temperature used since 1973, climate scientist and journalist Zeke Hausfather found that “they all show outcomes reasonably close to what has actually occurred”. Later in the same video, former Geology Professor Don Easterbrook then claims that “the Antarctic ice cap is not melting, [because] the average annual temperature there is 58 degrees below 0°” and then adds “I think it’s getting colder, very simple”. First, according to measurements reviewed by scientists John Turner and Thomas Bracegirdle in an article for the British Antarctic Survey, there is no evidence to support the claim that it’s getting colder. “Many long-term measurements from Antarctic research stations show no significant warming or cooling trends, and temperatures over most of the continent have been relatively stable over the past few decades” they write[11]. Moreover, temperatures vary greatly depending on the location of the weather station within the Antarctic, which is twice the size of Australia. According to the World Meteorological Association (WMO), in 2022 the average annual temperature ranges from about −10°C (14°F) on the Antarctic coast to −60°C (-76°F) at the highest parts of the interior[12]. Second, surface temperature is not the only factor responsible for ice cap melt. Don Easterbrook shows a lack of understanding of ice caps dynamics with his claim that ‘if the temperature is below 0°C, it cannot melt’. Ice caps are masses of ice formed on the Antarctic’s bedrock, and ice mass changes are dominated by changes in snowfall and glacier flow[13]. Additionally, the ice cap’s grounding lines and the bordering ocean’s temperatures also contribute to mass changes. Contrary to Easterbrook’s claims, observations show that Antarctic’s ice caps can lose mass (i.e. ‘melt’) at current temperatures. In fact, between 2003 and 2013 Antarctica’s ice caps have been losing mass at an estimated rate of 84 gigatons per year, according to a study by University of Bristol researcher Alba Martín-Español[14]. It is also important to note that some regions of the Antarctic are indeed warming. “The Antarctic Peninsula (the northwest tip near to South America) is among the fastest warming regions of the planet, almost 3°C over the last 50 years” said meteorologist Petteri Taalas in an article for the WMO in June 2021[15]. Significant warming is also occurring in the Southern Ocean, bordering the Antarctic. “For what matters most to us, which is sea level rise from melting Antarctica, the air/ocean temperature is increasing in a lot of regions along the coast” confirms Earth Systems Science researcher Eric Rignot. Influencing the Antarctic’s air temperatures, winds, and ice shelves, the Southern Ocean’s warming is yet another evidence of climate change impacting the frozen continent[16].Reviewers’ Feedback: Eric Rignot Professor, University of California Irvine & Jet Propulsion Laboratory: The Antarctic sea ice cover has been growing very slightly on average until about 2016*, at which point it started to decrease vigorously. Year to year fluctuations are expected and are not indicative of long term trends. To detect trends, you need multiple years and decades. The mean ground/air temperature in Antarctica is not getting colder. It also depends on whether you are looking at the coastline or the Antarctic plateau. For what matters most to us, which is sea level rise from melting Antarctica, the air/ocean temperature is increasing in a lot of regions along the coast. The Antarctic is part of the global climate system and also impacts the global climate system. The evolution of Antarctic sea ice has puzzled modelers for a while. They expected a decrease in sea ice, not a slight increase; and the abrupt change in 2016 was not expected. Overall, a decrease in sea ice cover since the 1970s was expected and observed. There are several interpretations of the recent record of Antarctic sea ice and its switching to a rapid decrease. I will not delve into this because the debate is still open on the thorough interpretation of these observations. I would simply say that it is consistent with a warming signal in Antarctica and the rest of the planet. *Editor’s note : 2016 is when the average Antarctic sea ice extent for November set a record low. The growth trend previously mentionedstarted to reverse in 2014.REFERENCES: 1 – NASA (2023). Arctic Sea Ice Minimum Extent. Global Climate Change Vital signs of the planet. Date accessed April 15 2023 2 – Farrell (2016). Corporate funding and ideological polarization about climate change. Proceedings of the National Academy of Sciences. 3 – Parkinson (2019). A 40-y record reveals gradual Antarctic sea ice increases followed by decreases at rates far exceeding the rates seen in the Arctic. Proceedings of the National Academy of Sciences. 4 – Turner et al. (2017). Solve Antarctica’s sea-ice puzzle. Nature. 5 – Gregory et al. (2002). Recent and future changes in Arctic sea ice simulated by the HadCM3 AOGCM. Geophysical Research Letters. 6 – Clem et al. (2022). Antarctic sea ice# 3: trends and future projections. Antarctic Environments Portal. 7 – Thompson et al. (2002). Interpretation of recent Southern Hemisphere climate change. Science. 8 – Stammerjohn et al. (2008). Trends in Antarctic annual sea ice retreat and advance and their relation to El Niño–Southern Oscillation and Southern Annular Mode variability. Journal of Geophysical Research: Oceans. 9 – Bintanja et al. (2013). Important role for ocean warming and increased ice-shelf melt in Antarctic sea-ice expansion. Nature Geoscience. 10 – Swart et al. (2013). The influence of recent Antarctic ice sheet retreat on simulated sea ice area trends. Geophysical Research Letters. 11 – John Turner et al. (2022). Antarctica and climate change. British Antarctic Survey. Date accessed April 21 2023. 12 – World Meteorological Organization (WMO) (2021). Antarctic heat, rain and ice prompt concern. World Meteorological Organization. Date Accessed April 21 2023. 13 – Pörtner et al. (2019). The ocean and cryosphere in a changing climate. IPCC special report on the ocean and cryosphere in a changing climate. 14 – Martín-Español et al. (2014). Spatial and temporal Antarctic Ice Sheet mass trends, glacio-isostatic adjustment, and surface processes from a joint inversion of satellite altimeter, gravity, and GPS data. Journal of Geophysical Research: Earth Surface. 15 – WMOs Evaluation Committee (2021). WMO verifies one temperature record for Antarctic continent and rejects another. World Meteorological Organization. Date Accessed April 21 2023. 16 – Holland et al. (2020). The southern ocean and its interaction with the Antarctic ice sheet. Science."
https://science.feedback.org/review/strands-cloud-behind-aeroplanes-trails-condensed-water-contrails-not-chemtrails-some-believe/,Inaccurate,"Facebook, William Deagle, 2023-03-18",Chemtrails contain toxic substances such as barium salts that are 10 thousand times more toxic to your nervous system than lead,,"Factually inaccurate: The consensus of scientific evidence shows that atmospheric barium levels have not increased due to deliberate programs to deposit barium salts in the atmosphere. Inadequate support: There is no evidence of a program to deliberately deposit chemicals into the atmosphere via so-called “chemtrails”. Misleading: Barium salts are not 10,0000 more toxic for the nervous system than lead. Although some barium salts are toxic, their toxicity is comparable to lead. ","Aeroplanes sometimes leave a trail of condensed water – a contrail – in their wake depending on factors such as altitude and weather conditions. The water condenses as the hot exhaust from the engine hits air, which is cold at high altitude. Some people have pointed to these as evidence of chemtrails but they are water vapour. There is no evidence of chemicals including barium salts deliberately deposited in the atmosphere to counter climate change or for any other reason.",Chemtrails contain toxic substances such as barium salts that are 10 thousand times more toxic to your nervous system than lead,"1 – Federal Environment Agency (2011) Chemtrails – Dangerous Atmospheric Experiments or Just Fiction? 2 – Moore et al. (2017) Biofuel blending reduces particle emissions from aircraft engines at cruise conditions Nature 3 – Voigt et al. (2021) Cleaner burning aviation fuels can reduce contrail cloudiness Communications Earth and Environment 4 – Shearer et al. (2016) Quantifying expert consensus against the existence of a secret, large-scale atmospheric spraying program Environmental Research Letters 5 – US Department of Health and Human Services (2007) Toxicological profile for barium and barium compounds 6 – Compounds, Agency for Toxic Substances and Disease Registry (last reviewed: October 21, 2014) Medical Management Guidelines for Barium (Elemental) and Selected Barium 7 – Centre for Disease Control (Last Reviewed: December 2, 2022) Blood Lead Reference Value","The claims that aeroplanes are deliberately depositing chemicals in the sky in chemtrails containing barium salts 10,000 times more toxic than lead are taken from a four hour long lecture by self-proclaimed prophet Dr Bill Deagle at the Granada Forum in 2006. The snippet has been posted multiple times on social media including Facebook, where one post received over 37,000 likes and 33,000 shares in March 2023. Despite the lack of evidence for chemtrails as demonstrated below, the idea retains a small but persistent following. A previous claim by GeoengineeringWatch.org allegedly proving that “Global climate engineering operations are a reality” and “the lingering, spreading jet aircraft trails, so commonly visible in our skies, are not just condensation” has already been reviewed by Climate Feedback. The consensus of the scientific community has not changed. When asked to comment on the claim in the current video, a spokesperson from the UK Met Office confirmed, “There is no such thing as a ‘chemtrail’, this is a conspiracy theory where people think commercial aircraft are spraying the population with chemicals. The vapor trails left behind aircraft in certain atmospheric conditions are called contrails, as an abbreviation for condensation trails.” Andreas Schütz, Head of Communication and spokesperson for the German Aerospace Centre responded with a link to the Federal Environment Agency’s own article: “Chemtrails – Dangerous Atmospheric Experiments or Just Fiction?”[1] where they clarify the issue (in German). The contrails sometimes mistaken for chemtrails form naturally as the hot exhaust from the aeroplane engines hit the cold air in the upper atmosphere. Christiane Voigt, Head of Department for Cloud Physics at the German Aerospace Center Institute of Atmospheric Physics, described the process in more detail: “Contrails are ice crystals, small snow particles and mainly contain water ice. The water condenses from the ambient atmosphere. The ice nucleates [starts to grow] on particle emissions from aircraft engines, mainly soot from the burned hydrocarbon compounds in the kerosene, ice nucleates and is persistent in cold and humid conditions. Contrails only form in 5% of the flights which have this cold and humid conditions mainly related to frontal weather systems”. Voigt has closely investigated the formation of contrails for her research, which has looked at how different compositions of fuel can affect aircraft induced cloud formation[2,3] from contrails. Although she highlights the potential climate impact of contrails, as she told Science Feedback, “Contrails are not toxic as they mainly constitute water.” A survey of experts In 2016 a group of researchers in California led by University of California, Irvine, Earth System Scientist Steven Davis, undertook one of the most comprehensive investigations of chemtrail claims[4]. They were concerned about the absence of scientific studies attempting to engage with claims of chemtrails despite the number of believers in the theory – 2.6% of an international survey of 3105 people at the time of the study. “There have been few attempts to seriously and scientifically evaluate the claims of its proponents”, report the authors of the paper. They hoped that an independent scientific appraisal of the claims would help to disambiguate them. They sent surveys to hundreds of experts in either atmospheric science and specifically condensation trails, or geochemistry and specifically atmospheric deposition of dust and pollution on the Earth’s surface. They defined experts as researchers who were authors of at least one of the top 100 most cited papers in the field. The surveys included various observations that have been cited as evidence that a program to deposit chemicals in the atmosphere – a secret large scale atmospheric program (SLAP) – is in operation, such as photos of trails left by aeroplanes and analysis of the concentration of elements including barium present in samples of pond sediment, airborne particles and snow. The elemental analyses indicate that the measured element concentrations in the airborne particles are above the maximum contaminant levels, but as one expert pointed out, “The concentrations per unit mass look like average soil or desert dust. The MCL [maximum contaminant levels] values are not relevant, and look to be based on drinking water standards.” On receipt of 49 responses to the contrail survey and 28 responses to the survey on atmospheric deposition, they found the experts unanimously disagreed with the chemtrail theory as “the most parsimonious [simplest] explanation for the depicted phenomena” in the photos of aeroplane trails. None of the experts noted unusual concentrations of barium. When asked to reflect on past experience, which includes their past observations of elemental concentrations from samples, 1 expert cited an observation that did not rule out the existence of chemtrails while the remaining 76 of the 77 experts who responded simply stated they “had not encountered evidence that indicates the existence of a secret, large-scale atmospheric spraying program (SLAP)”. Lead author Davis told Science Feedback that they were not surprised by the scientific consensus in response to the study. ”It takes a lot more effort to explain contrails and soil survey results by a secret large-scale spraying campaign than by natural phenomena.” Despite the strength of the conclusions he said that it was never the goal to settle the debate about chemtrails. “Our paper was intended to provide a scientific counter to conspiracy claims for those in the public who were seeking information on the issue, not to persuade conspiracy theorists who already had strongly held beliefs.” Barium salts are not 10,000 times more toxic than lead As for the claim that barium salts are 10,000 times more toxic than lead, this exaggerates the toxicity of barium salts. Some salts such as barium sulphate are insoluble and not readily absorbed. They are used as contrast agents for medical images, for instance to make x-rays of the gastrointestinal tract clearer. Over exposure to barium salts can lead to “vomiting, abdominal cramps, diarrhoea, difficulties in breathing, increased or decreased blood pressure, numbness around the face, and muscle weakness”[5,6] and excessive quantities can be fatal. However the toxicity does not grossly outweigh that of lead[7] as suggested in the video. Conclusion: Over the course of multiple studies by atmospheric scientists and geochemists for various projects there remains no evidence that chemicals are deliberately dumped in the sky by passing aeroplanes. There is good evidence for the simple explanation that these are ‘condensation of water’ trails. On these points experts in the field agree. In addition, barium salts are not 10000 times more toxic than lead. In summary the highlighted claims in Dr Beagle’s video are false or unsupported."
https://science.feedback.org/review/pre-human-changes-climate-not-negate-contemporary-human-influence-modern-warming/,Flawed reasoning,"Instagram, Social media users, 2023-01-17","Climate changed naturally in prehistoric eras, modern climate change is a naturally occurring phenomenon",,"Flawed reasoning: Climate change has occurred in the past without human influence. However, this does not indicate that non-human causes are driving modern warming, for which a consensus of scientific evidence shows that greenhouse gas emissions are responsible.","Scientists study all potential causes of climate change and have concluded, based on several independent lines of evidence, that modern warming is driven by human emissions of greenhouse gases. Other variables, such as orbital, solar and tectonic variations, contributed to climate change in earth’s geological history. However, these processes do not vary sufficiently fast to explain the rate of modern warming.",“Climate change is a naturally occurring phenomenon that can be tracked throughout prehistoric eras…Yes the planet is changing but that’s a constant part of life on this earth.”,,"A recent Instagram post alleges that “climate change is a naturally occurring phenomenon,” and that such change represents “a constant part of life on this earth.” While evidence shows that climate has been influenced by multiple factors in the past, scientists have found, through several independent lines of evidence, that modern climate change is driven by human emissions of greenhouse gases.[1-3] These greenhouse gases, like CO2, prevent heat from escaping from the atmosphere, which results in the warming of the surface of the planet. Other variables that may influence climate include volcanic eruptions, which simultaneously release particles that can cool the planet and greenhouse gases that warm the planet,[4]and the amount of energy released by the sun. Climate scientists study all potential causes of climate change by investigating the individual climatic influence of these different variables. When calculating the impact of each conceivable climate variable on global surface temperature, scientists have found that modern warming is impossible to explain without the greenhouse gases derived from human activities (see Figure 1).[1] By contrast, the sun–the preferred explanation for climate change in the Instagram post–contributes negligibly to modern warming (Fig. 1). Figure 1. Modeled influence of different climate forcing mechanisms on global mean surface temperature since 1850. Observations (dots) show a clear warming trend, which is consistent with the forcing resulting from increased greenhouse gas emissions (red). Without greenhouse gases added by human activities, the observed warming would not exist. Source: Carbon Brief. What about climate change in the past, prior to human influence? Scientists note that other variables played a more important role than CO2 on these different timescales. On the order of tens to hundreds of millions of years ago, key differences in the climate system included “the distribution of continents and ocean on the planet, the amount of volcanic activity (blocking out sunlight), and the brightness of the sun,” noted James Renwick, a climate scientist at Victoria University of Wellington in a previous review of a similar claim. “CO2 is very important for the energy budget of the earth, but it is not the only factor on very long time scales,” continued Renwick. On the order of tens to hundreds of thousands of years ago, earth’s orbit also played an important role in regulating the amount of solar energy received by the planet and global climate.[5] Invoking the notion that climate change has occurred in earth’s geological history without human influence in order to advance the narrative that humans are not responsible for modern climate change is a popular technique among climate contrarians. However, scientists say that this argument is flawed. “Here are logically identical arguments: ‘The New England Patriots scored touchdowns before Rob Gronkowski, so Rob Gronkowski can’t score touchdowns,’“ explained Mark Richardson, a climate scientist at Colorado State University in a previous review of a similar claim. “Or more simply: ‘Fires happened before humans, so humans can’t cause fires.’“ The 2017 US National Climate Assessment summarized the science on the cause of climate change this way: “This assessment concludes, based on extensive evidence, that it is extremely likely that human activities, especially emissions of greenhouse gases, are the dominant cause of the observed warming since the mid-20th century. For the warming over the last century, there is no convincing alternative explanation supported by the extent of the observational evidence.”References: 1 – Hausfather (2017). Analysis: Why scientists think 100% of global warming is due to humans. Carbon Brief 2 – Harries et al. (2001). Increases in greenhouse forcing inferred from the outgoing longwave radiation spectra of the Earth in 1970 and 1997. Nature 3 – Feldman et al. (2015). Observational determination of surface radiative forcing by CO2 from 2000 to 2010. Nature 4 – UCAR. How volcanoes influence climate 5 – Hays et al. (1976). Variations in the Earth’s orbit: pacemaker of the ice ages. Science"
https://science.feedback.org/review/link-between-co2-earth-temperature-well-established-despite-claims-fox-news-tom-harris/,Inaccurate,"Fox News, Tom Harris, 2022-10-12",Scientists have found no consistent correlation between CO2 and temperature; scientists do not know whether earth will warm or cool in future,,"Inaccurate:Past climate data show a correlation between CO2 concentration and global temperature, and physics shows CO2 is a greenhouse gas that strongly influences the temperature of the Earth’s surface.  Unsupported: Research has shown that solar activity variations are not enough to offset human-caused warming.","The link between global warming and atmospheric CO2 levels is well-established; in fact, increases in CO2 have warmed the planet multiple times over the last million or so years. Science shows unambiguously that current climate change is caused by human-emitted greenhouse gases. Based on this knowledge, scientists are confident that any grand solar minimum will not result in a cooling trend, as changes in total solar irradiance are not projected to be enough to offset human-caused warming. ","Scientists have found “No consistent correlation between carbon dioxide and earth’s temperature”; “It’s all based on models that don’t work”; “we don’t even know whether it’s going to warm or cool in the future”; various scientists show “we’re headed into a grand solar minimum around 2060, and that we’ll see gradual cooling over the next few decades”",,"In an interview with Fox News on 12 October, International Climate Science Coalition Executive Director Tom Harris made multiple misleading and inaccurate claims about climate change. The International Climate Science Coalition disputes the scientific consensus that human activities are causing the planet to warm. Harris, who has a background in mechanical engineering, quoted a university professor who Harris claimed found that there was “no consistent correlation between carbon dioxide and earth’s temperature.” “At times, CO2 was 1300% of today, and we were stuck in very cold conditions,” Harris said. On the contrary, paleoclimate data from the last 800,000-plus years show that the link between temperature and CO2 is well-established. Scientists discovered CO2’s role in warming the planet in the mid-19th century, noted James Renwick, Professor, Victoria University of Wellington, in a previous review of a similar claim. “Through the past 2.6 million years, the period of recent ice ages, carbon dioxide has gone up and down in step with temperature, bottoming out at around 180 parts per million in the depths of a “glacial maximum” and peaking at around 280 parts per million in the warmer interglacial periods, he said in the review. “Going back further, CO2 levels were certainly higher than present, but so were temperatures.” Figure 1 shows that CO2 concentrations have oscillated in conjunction with Earth’s temperature for the last 800,000 years. Figure 1 –Graphs show CO2 and temperature oscillations over the last 800,000 years for the global average and Antarctica. Credit: Ben Henley and Nerilie Abram, The Conversation. The Ordovician Period, which began 485.4 million years ago, saw CO2 levels that were 8 times higher than today.[1] Based on paleoclimate data, the later part of this period experienced glaciation – though that coolness does not invalidate the link between CO2 and warming, and was likely aided by a less-bright sun; the placement of the continents, which at that time were bunched together; and a drawdown of CO2. “There were periods of times when CO2 was very high, likely as high as 1500-2000 ppm,” Katrin Meissner, Professor, University of New South Wales, said in a previous review. “The ecosystems and biogeochemistry were adapted to these conditions, and they looked very different from today. There were no humans, many of the mammals around us did not exist. Not to mention that the sun’s energy output was slightly smaller during that time.” The last time the planet experienced CO2 levels this high was more than 3 million years ago. During that time – called the Mid-Pliocene Warm Period – the planet’s surface temperature was 4.5–7.2 degrees Fahrenheit (2.5–4 degrees Celsius) warmer than during the pre-industrial era, according to NOAA Climate.gov. Scientists are confident in the finding that increased CO2 concentrations are causing Earth’s temperature to rise.[2] As CO2 and other greenhouse gases are emitted into the atmosphere, they trap more of the sun’s energy, leading to warming. “It is unequivocal that human influence has warmed the atmosphere, ocean and land,” the IPCC notes in its Sixth Assessment Report.[3] While remaining in the atmosphere, CO2 prevents heat from escaping and consequently warms the surface of Earth – a concept that is popularly known as the greenhouse effect. This theory predicts that the increase in temperature will be proportional to the logarithm of the concentration of CO2, with a time-lag of about 20 years. Figure 2 shows that this is precisely what the data shows, hence providing a strong validation of the theory, in addition to other lines of evidence. Meanwhile, Figure 3 shows how global average annual temperature has increased in tandem with CO2 concentrations since 1880. Figure 2 –Global temperature plotted against atmospheric CO2 concentration. Note the logarithmic scale of the x-axis is due to the nature of the relationship between greenhouse gases and temperature.[7] Source: Berkeley Earth via a previous Climate Feedback review. Figure 3 – Global annual average temperature (as measured over both land and oceans) has increased by more than 1.5°F (0.8°C) since 1880 (through 2012). Red bars show temperatures above the long-term average, and blue bars indicate temperatures below the long-term average. The black line shows atmospheric carbon dioxide (CO2) concentration in parts per million (ppm). Credit: globalchange.gov. Harris also claimed that climate science is based on “models that don’t work.” Climate science is based both on observations – including temperature and other weather records – and models. Climate models simulate the earth’s climate system, and use mathematical equations to project how the planet may respond under different scenarios (i.e. low greenhouse gas emissions, business as usual emissions, etc.) as well as to recreate the climate at different times in the planet’s past. These models are complex: According to the National Centre for Atmospheric Science, “there are so many mathematical equations involved that a typical climate model includes enough code to fill 18,000 pages of printed text.” These models have proved to be accurate – though imperfect – tools. In fact, a 2019 study found that climate models have been skillful in projecting changes in the Earth’s temperature.[4] “Climate models published over the past five decades were generally quite accurate in predicting global warming in the years after publication, particularly when accounting for differences between modeled and actual changes in atmospheric CO2 and other climate drivers,” the study notes.[4] Scientists test models through a process called hind-casting, during which scientists run the model in the recent past and compare what the model shows to the observed climate and weather during that time period. This way, scientists are able to see how closely the model’s projections line up with actual weather and climate results – and, if needed, adjust the model accordingly. “Climate models are imperfect representations of nature that represent just one tool scientists use to understand how and why Earth’s climate varies,” Timothy Myers, Postdoctoral Researcher at Lawrence Livermore National Laboratory, said in a previous review. “Climate models are good at simulating some physical processes and deficient in their simulation of other processes. Simply because the climate is complex does not mean we cannot reasonably model or understand it.” Harris also claimed that experts aren’t sure whether the globe will warm or cool in the future, and that “various people that study the sun” say that Earth is headed towards a grand solar minimum, which will result in gradual cooling. Research, however, disputes this claim of future cooling. A 2016 study found that human emissions would delay the next ice age by about 50,000 years.[5] And a 2013 study found that a grand solar minimum would slow down global warming – but that the rate of warming would go back up once total solar irradiance started to rise again.[7] “Therefore, results here indicate that such a grand solar minimum would slow down and somewhat delay, but not stop, human-caused global warming,” the study concludes.[6] Figure 4 – Rise of global temperature for two different emission scenarios (A1B, red, and A2, magenta). The dashed lines show the slightly reduced warming in case a Maunder-like solar minimum should occur during the 21st century. The blue line represents global temperature data. Source: Potsdam Institute for Climate Impact Research; taken from a previous Climate Feedback Review. NASA agrees that if a grand solar minimum were to occur in the next few decades, it would not be enough to offset human-caused warming. “The warming caused by the greenhouse gas emissions from the human burning of fossil fuels is six times greater than the possible decades-long cooling from a prolonged Grand Solar Minimum,” NASA writes in a 2020 article. “Even if a Grand Solar Minimum were to last a century, global temperatures would continue to warm. The reason for this is because more factors than just variations in the Sun’s output change global temperatures on Earth, the most dominant of those today is the warming coming from human-induced greenhouse gas emissions.” References: [1] Pancost et al. (2013) Reconstructing Late Ordovician carbon cycle variations. Geochimica et Cosmochimica Acta. [2] Stips et al. (2016) On the causal structure between CO2 and global temperature. Scientific Reports. [3] IPCC (2021) Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. [4] Hausfather et al. (2019) Evaluating the Performance of Past Climate Model Projections. Geophysical Research Letters. [5] Ganopolski et al (2016) Critical insolation–CO2 relation for diagnosing past and future glacial inception. Nature. [6] Meehl et al. (2013) Could a future “Grand Solar Minimum” like the Maunder Minimum stop global warming? Geophysical Research Letters. [7] Huang et al. (2004). Why logarithmic? A note on the dependence of radiative forcing on gas concentration. Journal of Geophysical Research: Atmospheres."
https://science.feedback.org/review/scientists-found-modern-climate-change-caused-entirely-by-human-activity-contrary-recent-speculation-joe-rogan-experience/,Flawed reasoning,"The Joe Rogan Experience, Joe Rogan, 2022-10-02","“The question is, ‘how much of an impact do we have on [climate]?’ That has not totally been quantified”; climate change is happening anyway, “The ice age happened without us…It’s probably this constant cycle”.",,"Flawed reasoning: Scientists have quantified human influence on the climate system and found it to be responsible for the entirety of modern warming. Other non-human factors are capable of influencing Earth’s climate, as has occurred previously in Earth’s history. However, Earth’s climate has been stable for 11,000 years before humans started releasing large amounts of greenhouse gasses and scientists have determined that natural factors are insufficient to explain modern warming.","In quantifying the impact of different possible drivers of climate change, scientists have identified that human activity is responsible for the entirety of modern global warming. There is no scientific evidence available to support an alternative explanation. While Earth’s climate has changed in the past due to “natural” (non-human) causes, such changes occurred over much slower timescales compared to present-day warming.","“Temperature has always been up and down.”; “The question is, ‘how much of an impact do we have on [climate]?’ That has not totally been quantified. They’re not exactly sure. They know it’s a significant impact, but [climate change] is happening anyway [without human influence]…The ice age happened without us…It’s probably this constant cycle”.",,"In a recent podcast episode, Comedian and Ultimate Fighting Championship commentator Joe Rogan questioned the extent to which human activity impacts climate. “The ice age happened without us”, Rogan noted, later suggesting that modern climate change could be part of a “constant cycle”. Human influence on the climate system is multifaceted. Emissions of greenhouse gasses, such as CO2, warm the lower atmosphere and the surface of the planet. Changes in land use may affect the planet’s ability to sequester carbon, further impacting our climate. Anthropogenic aerosols–tiny solid or liquid particles suspended in the atmosphere–may both cool or warm the Earth depending on their properties.[1] Non-human variables, such as changes in the sun and volcanic activity, can also influence climate. Scientists have studied all of these possible causes of climate change, or forcing mechanisms. This is done by calculating the climatic impact of each individual forcing mechanism over time and then comparing it with observations of temperature change. When all of the forcing mechanisms are put together, it becomes evident that anthropogenic greenhouse gas emissions are the only mechanism that can reproduce the observed warming trend (Fig. 1). By contrast, the impact of all other factors (e.g., solar activity and aerosols) on climate has been relatively minor since 1850 (Fig. 1). In fact, without anthropogenic greenhouse gas emissions, these other factors would have resulted in a slight cooling trend, rather than the observed warming.[2] Figure 1. Modeled influence of different climate forcing mechanisms on global mean surface temperature since 1850. Observations (dots) show a clear warming trend, which is consistent with the forcing resulting from increased greenhouse gas emissions (red). Without greenhouse gases added by human activities, the observed warming would not exist. Source: Carbon Brief. “The empirical evidence that increases in greenhouse gas concentrations (from fossil fuel burning) are the primary cause of century-scale warming is that observed global temperatures have risen in line with what would be expected from the observed increase in greenhouse gas concentrations and observations of natural drivers of climate change (e.g. solar output and volcanic eruptions) indicate that natural drivers are not causing warming”, said climate scientist Patrick Brown in a previous review. Brown’s comments are reflected in the findings of the world’s most comprehensive climate change report by the Intergovernmental Panel on Climate Change (IPCC), which was prepared by hundreds of independent scientific experts in 2021 and concluded that it is “unequivocal that human influence has warmed the atmosphere, ocean and land.”[3] What of the ice ages, then? Referencing claims by his former podcast guest, Steve Koonin, a physicist who previously authored a book that misrepresents climate science, Rogan goes on to say that “[temperature] has always been up and down” according to “core samples”, or reconstructions of Earth’s past climate based on geological proxies. Paleoclimate evidence indicates that the Earth’s climate has been stable for the last 11,000 years, a period known as the Holocene, which allowed human civilization to flourish.[4] The Holocene began at the end of the most recent ice age, during which global temperature dropped by an average of about 4°C[4] Variations between ice ages, also called glacial periods, and warmer intervals between them, called interglacials, are a feature of Earth’s climate over the last 2.6 million years. What causes these major paleoclimate shifts? Changes in astronomical dynamics–the eccentricity of Earth’s orbit around the sun, the precession of the equinoxes and axial tilt–result in differences in the distribution of solar energy on Earth, which influences global temperature and ice volume. Thus, astronomical variability has been referred to as the “pacemaker of the ice ages”.[5] However, this isn’t the full picture. Rather, initial orbital-driven climate change can trigger multiple synergistic shifts in the Earth system, which affect the exchange of CO2 between the ocean and the atmosphere. Scientists have therefore concluded that this greenhouse gas, which is responsible for all of modern warming, was also an important mechanism for amplifying climate change initiated by astronomical processes in the geological past.[4] This is supported by ice core records, which show a tight link between atmospheric CO2 concentration and temperature over the last 800,000 years[6,7] (Fig. 2). Figure 2. Atmospheric CO2 (top) and temperature change (bottom) over the last 800,000 years. Note that high levels of CO2 are associated with high temperatures and low levels of CO2 are associated with low temperatures. Chart modified from Data from the University of Copenhagen Centre for Ice and Climate. Prior to human influence, CO2 varied from approximately 200 to 300 ppm over thousands of years. However, the situation today, in which CO2 levels exceeded 400 ppm in the course of several decades, is unprecedented in the past million years (Fig. 3). Figure 3. Atmospheric CO2 concentration over the last 800,000 years. Note that modern levels of >400 ppm, driven by anthropogenic emissions, are a notable departure from pre-human variability. Source: NASA. Climate contrarians frequently invoke the fact that Earth’s climate has changed in the past, without human influence, to cast doubt upon the consensus of scientific evidence[8,9] that points to modern warming driven by human activity. However, this argument is flawed, noted Mark Richardson, a climate scientist at Colorado State University. “Here are logically identical arguments: ‘The New England Patriots scored touchdowns before Rob Gronkowski, so Rob Gronkowski can’t score touchdowns,’ said Richardson. “Or more simply: “‘Fires happened before humans, so humans can’t cause fires.’” Contrary to Rogan’s speculations, all of the scientific evidence indicates that human emissions of greenhouse gas are driving modern climate change.References: 1 – NOAA Geophysical Fluid Dynamics Laboratory. Aerosols and Climate 2 – Hausfather (2017). Analysis: Why scientists think 100% of global warming is due to humans. Carbon Brief 3 – IPCC (2021). Sixth Assessment Report 4 – Hausfather (2020). Explainer: How the rise and fall of CO2 levels influenced the ice ages. Carbon Brief 5 – Hays et al. (1976). Variations in the Earth’s orbit: pacemaker of the ice ages. Science 6 – Lüthi et al. (2008). High-resolution carbon dioxide concentration record 650,000–800,000 years before present. Nature 7 – EPICA Community Members (2004). Eight glacial cycles from an Antarctic ice core. Nature 8 – Oreskes (2004). The scientific consensus on climate change. Science 9 – Cook et al. (2013) Quantifying the consensus on anthropogenic global warming in the scientific literature. Environmental Research Letters"
https://science.feedback.org/review/the-epoch-times-prints-range-of-inaccurate-misleading-claims-climate-changes-impacts-causes-patrick-moore/,Incorrect,"The Epoch Times, Patrick Moore, 2022-09-06",CO<sub>2</sub> is not the cause of our current warming trend; Arctic sea ice has expanded in recent years; Polar bears’ population is growing and is not threatened by climate change; CO<sub>2</sub> is good for plant life,,"Incorrect: The data is clear that carbon dioxide emitted by human activities is driving current rates of climate change.  Misleading: Long-term records of Arctic sea ice show a consistent decline.  Inaccurate: Polar bear populations are estimated at 22,000 - 30,000 individuals, not 50,000. Research shows that climate change threatens polar bear populations by disrupting their hunting habitat.  Misleading: Plants need CO2 to survive, but the buildup of CO2 in the atmosphere is leading to numerous climatic changes, including heat waves, drought and wildfires, that are damaging for plants and the rest of the planet. ","Climate change has led to a decades-long decline in Arctic sea ice, putting polar bears – and other Arctic organisms – at risk of significant population declines. Meanwhile, based on all existing evidence, scientists are confident that the buildup of carbon dioxide and other greenhouse gases in the atmosphere is driving current climate change, which is leading to a range of negative impacts for plant, animal and human populations. ","”If carbon dioxide was the main cause of warming, then there should be a rise in temperature along the carbon dioxide curve, but it doesn’t“; “They say the polar bear will go extinct in 2100... In fact, this past winter in the Arctic saw an expansion of ice from previous years, and Antarctica was colder during the last winter than in the past 50 years“; “We do not know the cause of these periodic fluctuations in temperature, but it was certainly not CO2; A study in 2013 found that increased levels of carbon dioxide (CO<sub>2</sub>) have helped boost green foliage across the world’s arid regions over the past 30 years.“",,"The Epoch Times laid out a range of inaccurate and misleading claims from Canadian industry consultant and former activist Patrick Moore in a September article, outlining statements from Moore taken from emails between himself and South Korean professor Seok-soon Park in late 2021. Polar bears and melting sea ice In the article, Moore claims that the polar bear population has “increased from 6,000 to 8,000 in 1973 to 30,000 to 50,000 today,” and that the polar bear is not threatened by melting sea ice in the Arctic. In fact, as of 2015, which was the last time the animal was assessed, the IUCN estimates the total population of polar bears at 22,000 to 31,000 individuals.[1] Recent research has found that polar bears face an uncertain future as Arctic sea ice melts: Because the animals depend on sea ice for hunting, and because seals, their prey of choice, also depend on sea ice for breeding and making dens, sea ice loss is making it more difficult for polar bears to hunt. A 2020 study estimated that, “with high greenhouse gas emissions, steeply declining reproduction and survival will jeopardize the persistence of all but a few high-Arctic subpopulations [of polar bears] by 2100.”[2] (Climate Feedback evaluated New York Times coverage of this study in 2020 and found it to be correct. We also evaluated a claim similar to Moore’s in 2020, which asserted that polar bear populations were “growing” and “thriving,” and found it to be incorrect). Numerous other studies have warned of the threat posed to polar bear populations by melting sea ice. A 2021 study published in Earth’s Future predicts, for instance, that under high warming (over 2°C) scenarios, “seals will not be able to den (Hezel et al., 2012); [and] polar bears will not have sufficient marine food sources,” due to loss of ice in the Arctic Circle.[3] In addition some studies have already documented negative impacts of sea ice loss, including lower survival rates, in polar bear subpopulations.[8-9] How climate change impacts the Arctic and Antarctic Moore also claims that “this past winter in the Arctic saw an expansion of ice from previous years, and Antarctica was colder during the last winter than in the past 50 years.” Scientists keep records on Arctic sea ice minimums (the lowest amount of cover that the sea ice reaches in summer) and maximums (the highest amount of cover sea ice reaches in winter). This February, the region’s winter sea ice extent was the 10th-lowest in the satellite record maintained by the National Snow and Ice Data Center. Though it’s true that that’s a slightly higher cover than last year – which ranked 7th-lowest in the satellite record – Arctic sea ice extent has been trending downwards since reliable satellite record keeping began in 1979, with minimum extents declining at about 13% per decade.[4] Figure 1: Graph shows decline in August Arctic sea ice extent from 1979 – 2022. Credit: National Snow and Ice Data Center. Figure 2: Graph shows decline in average February sea ice extent from 1979 – 2022. Credit: National Snow and Ice Data Center. The Amundsen-Scott South Pole Station did experience a record-cold six-month stretch between April and September 2021. As Reuters notes in a 2021 fact-check, however, this six-month period does not invalidate the decades of data on global planetary temperature trends. Climate change’s impact on Antarctica also differs greatly from its impact on the Arctic, a fact that scientists are still working to understand. While sea ice thickness and extent has declined over the last few decades, sea ice in Antarctica has remained stable. There are numerous contributing factors to this dichotomy, including differences in geography, wind strength and ice thickness between the two regions, but the differences do not cast doubt on the globe’s overall warming trend. In addition, the sea ice loss trends in the Arctic dwarf the slight growth trends Antarctica experienced up until 2014. “Looking at the trend in annual mean ice extent over the full period we have satellite data for (1979 to the end of 2021), the trends in the Antarctic are nearly ten times smaller than those in the Arctic (as well as being positive, not negative),” Caroline Holmes, Polar Climate Scientist at the British Antarctic Survey, said in a previous Climate Feedback review. “This is a fair comparison, as the average ice extent over those periods is similar.” CO2: A known driver of climate change Moore also claims that “the world has been warming since about the year 1700, 150 years before we were using fossil fuels.” He also references the Little Ice Age and Medieval Warm Period, which research has suggested were both prompted by natural causes: The Medieval Warm Period was drivenlargely by an increase in solar radiation and decrease in volcanic eruptions, while the Little Ice Age may have been triggered by warm Atlantic water entering the Nordic seas.[10] However, one study examined the Little Ice Age and Medieval Warm Period and found that the time periods were not as “globally coherent” as previously assumed, and could be considered more regional climate events.[11] The study states: “Against this regional framing, perhaps our most striking result is the exceptional spatiotemporal coherence during the warming of the twentieth century. This result provides further evidence of the unprecedented nature of anthropogenic global warming in the context of the past 2,000 years.” Moore cast doubt on the consensus that current rates of climate change are being driven by Carbon Dioxide and other greenhouse gases. He provided a graphic of CO2 levels graphed against temperatures in Central England and noted: “If carbon dioxide was the main cause of warming, then there should be a rise in temperature along the carbon dioxide curve, but it doesn’t.” In reality, global records show a clear link between increasing levels of Carbon Dioxide and increasing temperatures. They also show that this current rate of temperature increase is far fasterthan past changes in temperature.Figure 3: Yearly temperature compared to the twentieth-century average (red and blue bars) from 1880–2019, based on data from NOAA NCEI, plus atmospheric carbon dioxide concentrations (gray line): 1880-1958 from IAC, 1959-2019 from NOAA ESRL. Original graph by Dr. Howard Diamond (NOAA ARL), and adapted by NOAA Climate.gov. Caption credit: Climate.gov. According to NASA, industrial activities “have raised atmospheric carbon dioxide levels by nearly 50% since 1750.” Scientists know that the CO2 building up in the Earth’s atmosphere is from human activities because of its isotopic fingerprint, which indicates that the CO2 originated from ancient plant material – i.e. fossil fuels. Accurate global temperature records date back to 1880, with temperature data from years prior to 1880 estimated using “proxies” – things like tree rings and fossilized pollen. Research has traced human-caused warming to the 1830s – towards the end of the industrial era, which began in the mid 1750s.[5] The preindustrial era, which is hard to define definitely but which one study set as 1720–1800, was “0.55°–0.80°C cooler than 1986–2005 and that 2015 was likely the first year in which global average temperature was more than 1°C above preindustrial levels.”[6] Figure 3: Changes in the temperature of the Northern Hemisphere from surface observations (in red) and from proxies (in black; uncertainty range represented by shading) relative to 1961-1990 average temperature. These analyses suggest that current temperatures are higher than seen globally in at least the last 1700 years, and that the last decade (2001 to 2010) was the warmest decade on record. (Figure source: adapted from Mann et al. 2008). Caption and graphic Courtesy globalchange.gov. Moore references research that has found that excess levels of CO2 in the atmosphere can lead to global greening – an increase of leaf cover across the planet. Research does support this claim: A 2016 study, for instance, found that from 1982–2009, the globe showed “a persistent and widespread increase of growing season integrated LAI [Leaf Area Index] (greening) over 25% to 50% of the global vegetated area.”[7] But, as Climate Feedback explained earlier this year, that doesn’t mean that CO2 is harmless. “The benefit[s] of increasing CO2 concentrations for plant growth are increasingly being outweighed by the negative impacts, especially of global warming,” Sara Vicca, assistant professor at the University of Antwerp, told Climate Feedback in a previous review. “This is true for natural as well as agricultural ecosystems.” Science Feedback has reviewed inaccurate claims by Patrick Moore about climate change’s causes before. As cataloged by Open Feedback, the Epoch Times has been shown to have published misinformation in the past. Update: A previous version of this post stated that Arctic sea ice maximums were declining by 13% per decade. In fact, Arctic sea ice minimums are declining by 13% per decade, while maximums are declining by about 2.8% per decade. This post has been updated to reflect this fact. References: [1] Wiig et al. (2015) Ursus maritimus. The IUCN Red List of Threatened Species. [2] Molnár et al. (2020) Fasting season length sets temporal limits for global polar bear persistence. Nature Climate Change. [3] Newton et al. (2021). Defining the “Ice Shed” of the Arctic Ocean’s Last Ice Area and Its Future Evolution. Earth’s Future. [4] How is Arctic sea ice changing? (2020). National Snow and Ice Data Center. [5] Abram et al. (2016) Early onset of industrial-era warming across the oceans and continents. Nature. [6] Hawkins et al. (2017) Estimating Changes in Global Temperature since the Preindustrial Period. Bulletin of the American Meteorological Society. [7] Zhu et al. (2008). Greening of the Earth and its drivers. Nature. [8] Lunn et al (2016) Demography of an apex predator at the edge of its range: impacts of changing sea ice on polar bears in Hudson Bay. Ecological Applications. [9] Regehr et al (2007) Effects of earlier sea ice breakup on survival and population size of polar bears in Western Hudson Bay. The Journal of Wildlife Management. [10] Lapointe et al. (2021) Little Ice Age abruptly triggered by intrusion of Atlantic waters into the Nordic Seas. Science Advances. [11] Neukom et al. (2019). No evidence for globally coherent warm and cold periods over the preindustrial Common Era. Nature."
https://science.feedback.org/review/scientific-evidence-indicates-modern-warming-driven-by-co2-contrary-to-richard-lindzen/,Incorrect,"Climate Change is Crap, Richard Lindzen, 2022-08-30",“Believing CO2 controls the climate is pretty close to believing in magic.”,,Incorrect: Several independent lines of scientific evidence based on observational datasets and modeling indicate that current climate change is driven by human emissions of greenhouse gases such as CO2. Scientific evidence shows that changes in all other potential climate variables are insufficient to explain modern warming.,"Climate change is not only evidenced by increased global average temperature, but also by increased ocean-heat content, Arctic sea ice decline and sea level rise. All of the scientific evidence, including observational datasets and climate models, indicates that the warming and disruption of Earth’s climate system since the onset of the industrial era is due to human emissions of greenhouse gases such as CO2.","“...What is the likelihood of the climate (which, itself, consists of many variables and not just globally averaged temperature anomaly) is controlled by this 2% perturbation in a single variable?”; “Believing CO2 controls the climate is pretty close to believing in magic.”",,"A quote on Facebook attributed to Richard Lindzen, a retired meteorologist who has received funding from fossil fuel interests, claims that climate change cannot likely be caused by a “single variable” such as CO2 due to the complexity of the climate system. Climate is indeed a complex system consisting of multiple variables. However, its complexity does not indicate that scientists do not understand the main variables that are driving contemporary warming. Since 1950, atmospheric CO2 concentrations have climbed from just above 300 parts per million (ppm) to over 400 ppm (Fig. 1). This change, caused by fossil fuel use, is particularly startling in the context of past atmospheric CO2 concentrations, which ice core reconstructions indicate have fluctuated between around 200 and 300 ppm over periods of thousands of years during the last 800,000 years (Fig. 1).[1,2] While remaining in the atmosphere, CO2 prevents heat from escaping and consequently warms the surface of Earth – a concept that is popularly known as the greenhouse effect. This theory predicts that the increase in temperature will be proportional to the logarithm of the concentration of CO2, with a time-lag of about 20 years. Figure 2 shows that this is precisely what the data shows, hence providing a strong validation of the theory, in addition to other lines of evidence. “The role of CO2 in warming the Earth was discovered in the mid-19th century,” says James Renwick, a climate scientist at Victoria University of Wellington in a previous review of a similar claim. Figure 1. Variations in atmospheric CO2 concentration over the last 800,000 years. Source: NASA. Figure 2. Global temperature plotted against atmospheric CO2 concentration. Note the logarithmic scale of the x-axis is due to the nature of the relationship between greenhouse gases and temperature.[3]Source: Berkeley Earth. But how can scientists be certain that CO2 is driving today’s warming and not, as Lindzen argues, one of the other several variables of Earth’s climate system? Scientists have calculated the influence of individual variables on Earth’s climate, and consistently find that human activities, dominantly CO2 emissions, have driven warming following the onset of the industrial era (Fig. 3). Figure 3. Time series of effective radiative forcing (warming) caused by various mechanisms. Note that carbon dioxide (gray) contributes more to warming than all of the other well-mixed greenhouse gases (WMGHG). Note also that the majority of warming is caused by carbon dioxide and other greenhouse gases. Source: U.S. Fourth National Climate Assessment. “The warming from the late 1800s to the present is all due to human-caused climate change, because natural factors have changed little since then and even would have caused a slight cooling over the last 70 years rather than the warming we have observed”, noted Timothy Osborn, a climate scientist at the University of East Anglia, in a previous review. Atmospheric observations also support warming driven by greenhouse gases. The scientific understanding of greenhouse gas physics predicts that CO2 would selectively warm the lower section of the atmosphere, called the troposphere, while cooling the upper part of the atmosphere, called the stratosphere. Thus, if CO2 is responsible for Earth’s temperature increase, we would expect to see a simultaneous warming of the troposphere and cooling of the stratosphere[4-6], which is exactly what the data show (Fig. 4). Figure 4. Global temperature variations in the upper atmosphere (top graph) and in the lower atmosphere (bottom graph) since the 1960s. We observe a warming at the surface and a cooling above, which is consistent with the effect of added greenhouse gases in the atmosphere. Source: Met Office Hadley Centre.If you are interested in learning more about how carbon dioxide can have such an important effect on global climate when its concentration is so small, read this article in The Conversation.Updates: 9 September 2022: Content related to Lindzen’s “2% perturbation” statement was removed due to a lack of clarity about what perturbation the author refers to. References: 1 – Lüthi et al. (2008). High-resolution carbon dioxide concentration record 650,000–800,000 years before present. Nature 2 – EPICA Community Members (2004). Eight glacial cycles from an Antarctic ice core. Nature 3 – Huang & Shahabadi (2004). Why logarithmic? A note on the dependence of radiative forcing on gas concentration. Journal of Geophysical Research: Atmospheres. 4 – Lockwood & Fröhlich (2007) Recent oppositely directed trends in solar climate forcings and the global mean surface air temperature. Proceedings of the Royal Society of London A: Mathematical, Physical and Engineering Sciences. 5 – Lockwood (2008) Recent changes in solar outputs and the global mean surface temperature. III. Analysis of contributions to global mean air surface temperature rise. Proceedings of the Royal Society of London A: Mathematical, Physical and Engineering Sciences. 6 – Santer et al. (2013). Human and natural influences on the changing thermal structure of the atmosphere. Proceedings of the National Academy of Sciences."
https://science.feedback.org/review/letter-there-is-no-climate-emergency-repeats-inaccurate-claims-about-climate-science-daily-sceptic-toby-young/,Incorrect,"Daily Sceptic, Toby Young, 2022-08-18","“Natural variation explains a substantial part of global warming observed since 1850;” no statistical evidence that global warming is intensifying natural disasters, or making them more frequent.",,"Incorrect: Natural (non-human) drivers of climate change have been mostly stable since the onset of modern warming and all the available scientific evidence implicates human greenhouse gas emissions as the primary culprit. Scientific evidence also indicates that climate change is contributing to intensified or more frequent natural disasters such as heatwaves, drought and heavy rainfall.","Scientific evidence shows that climate change is driven by human activities, as recognized by the world’s authoritative scientific bodies such as the U.N.’s Intergovernmental Panel on Climate Change, the U.S. National Academy of Sciences and the U.K. Royal Society. These scientific bodies, composed of experts in the field of climate science, have concluded that climate change is predominantly driven by human emissions of greenhouse gases. The “World Climate Declaration” group, largely composed of non-experts, relies on several inaccurate claims about the science to arrive at an alternative conclusion.","“The political fiction that humans cause most or all climate change and the claim that the science behind this notion is ‘settled’, has been dealt a savage blow by the publication of a ‘World Climate Declaration (WCD)’ signed by over 1,100 scientists and professionals.” “Natural variation explains a substantial part of global warming observed since 1850;” “There is no statistical evidence that global warming is intensifying hurricanes, floods, droughts and such-like natural disasters, or making them more frequent.”",,"An article authored by Toby Young in the Daily Sceptic, a website with a history of publishing scientifically unfounded claims, reports on an open letter signed by “1,200 scientists and professionals.” The letter, entitled the “World Climate Declaration,” is claimed to have “dealt a savage blow” to the notion that human emissions of greenhouse gases are responsible for climate change. The World Climate Declaration group, which has links to fossil fuel interests, has made similar allegations in the past, which were previously analyzed by scientists and found to be inaccurate. Young and the letter argue that, rather than greenhouse gas emissions, today’s warming may be a natural event following the end of the Little Ice Age, an interval of particularly cold conditions between around 1400 to 1700.[1] Young quotes Antonio Zichichi, a physicist with ties to the Heartland Institute think tank who does not have a background in climate science: “Natural variation explains a substantial part of global warming observed since 1850…the Earth’s climate has varied for as long as the planet has existed, with natural cold and warm periods.” While natural variations can impact climate, invoking the existence of such natural variability (i.e., non-human factors such as solar variability and volcanic activity) to explain contemporary warming is scientifically unsound. Examining all plausible climate drivers reveals that natural variability has exerted a relatively minor influence on total climate change since the industrial era (Fig. 1). By contrast, human emissions of CO2 and other greenhouse gases are the dominant factors that have driven warming over this interval.[2,3]Figure 1. Time series of effective radiative forcing (warming) caused by various mechanisms. Note that carbon dioxide (gray) contributes more to warming than all of the other well-mixed greenhouse gases (WMGHG). Note also that the majority of warming is caused by carbon dioxide and other greenhouse gases. Source: U.S. Fourth National Climate Assessment. “The warming from the late 1800s to the present is all due to human-caused climate change, because natural factors have changed little since then and even would have caused a slight cooling over the last 70 years rather than the warming we have observed”, said Timothy Osborn, a climate scientist at the University of East Anglia, in a previous review of a similar claim. “Climate scientists study the causes of warming and cooling periods and calculate their effects on our climate. These studies show that natural warming after the Little Ice Age was complete by the late 1800s,” added Osborn. Scientists estimate the effects of various potential climate drivers by running model simulations, mathematical representations of the climate system. The effectiveness of climate models is evaluated by their ability to capture real-world climate trends. Models used by the IPCC have been faithfully predicting climate since the 1970s, which gives researchers confidence in their performance.[4] Modeling results consistently indicate that the observed increases in surface temperature and ocean heat content are not possible to explain with natural variability alone and rather demonstrate that human activities are responsible for the warming trend (Fig. 2).Figure 2. IPCC climate model simulations of land and ocean surface temperatures in addition to ocean heat content since the beginning of the twentieth century using natural and anthropogenic (e.g., greenhouse gas emissions) climate forcings (red) and non-anthropogenic forcings alone (blue). Black lines denote observations. Source: IPCC AR5. Young’s article later repeats another claim about the merits of CO2 with a quote from the letter, calling the greenhouse gas “beneficial for nature” and responsible for “greening the Earth.” This narrative was explored in a recent Climate Feedback insight article, in which scientists like Sara Vicca, a carbon-cycle expert at the University of Antwerp, were featured. While it is true that plants need CO2, this does not indicate that warming driven by greenhouse gas emissions is harmless. “The benefit[s] of increasing CO2 concentrations for plant growth are increasingly being outweighed by the negative impacts, especially of global warming,” said Vicca. For example, extreme events associated with CO2-driven warming, such as drought, can adversely impact plant life.[5] The letter also contests a relationship between climate change and extreme events, claiming that “there is no statistical evidence that global warming is intensifying hurricanes, floods, droughts and such-like natural disasters, or making them more frequent.” Such a claim is at odds with the most recent IPCC report,[2] which states in its summary for policymakers that “human-induced climate change is already affecting many weather and climate extremes in every region across the globe.” The IPCC further notes that “evidence of observed changes in extremes such as heatwaves, heavy precipitation, droughts, and tropical cyclones, and, in particular, their attribution to human influence, has strengthened since AR5 [Assessment Report 5, a previous IPCC report].” Moreover, the IPCC states with high confidence that “increases in frequency, intensity and severity of droughts, floods and heatwaves, and continued sea level rise will increase risks to food security in vulnerable regions from moderate to high between 1.5°C and 2°C global warming level [the maximum level of warming that the Paris Agreement calls for], with no or low levels of adaptation” (Fig. 3). Figure 3. Severity of various climate impacts occurring (right) under different scenarios of warming. Note that extreme weather events (RFC2) are expected to intensify with warming. Source: IPCC AR6. Given the volume of inaccurate claims made in the letter and Young’s article, it is perhaps surprising that “1,200 scientists and professionals” agree with its content. It is, however, instructive to examine the credentials of the signatories. Of the 1,200, only a handful mention having a background in climate science. Some of these individuals claim that they have a master’s degree in the subject matter while others identify as “independent researchers” without mentioning specific credentials. Many signatories have degrees in unrelated fields (i.e., psychology) or work in the fossil fuel industry. Such findings are similar to Climate Feedback’s review of the signatories to the previous letter.References: 1 – Mann et al. (2009) Global Signatures and Dynamical Origins of the Little Ice Age and Medieval Climate Anomaly. Science. 2 – IPCC (2021) Sixth Assessment Report. 3 – US Fourth National Climate Assessment, Climate Science Special Report 4 – Hausfather et al. (2019) Evaluating the Performance of Past Climate Model Projections. Geophysical Research Letters. 5 – Xu et al. (2019) Increasing impacts of extreme droughts on vegetation productivity under climate change. Nature Climate Change"
https://science.feedback.org/review/carbon-dioxide-emissions-humans-major-driver-climate-change-jerome-corsi-claims-cbn-news/,Incorrect,"CBN News, Jerome Corsi, 2022-07-29",Carbon dioxide is not a climate heat driver; we had an ice age when the Earth had extraordinarily larger amounts of carbon dioxide; in the 1970s scientists thought we were going to have a new ice age.,,"Incorrect: As a greenhouse gas, additional carbon dioxide in the atmosphere, driven by human emissions, exerts a warming effect on the planet and has been demonstrated to be the dominant driver of modern global warming and climate change.  Misleading: Carbon dioxide is the dominant driver of contemporary warming, which is happening very rapidly. However, other factors were also responsible for regulating Earth’s climate on longer timescales in the geological past, such as the distribution of continents, volcanic activity and the brightness of the sun.  Misleading While a few studies in the 1970s speculated about the possibility of global cooling, the majority of the climate research community indicated that future warming would occur. ","Earth’s climate is a complicated system with multiple potential driving mechanisms. However, scientists have evaluated all possible driving mechanisms of contemporary global warming and have consistently concluded that human emissions of greenhouse gases are the primary culprit. While climate change has occurred in Earth’s geological history independently of humans, it is misleading to invoke these relatively slow changes under very different Earth-system conditions (e.g., variability in tectonics, solar forcing, orbital conditions and volcanism) in order to discredit the findings of climate science. ","“[Carbon dioxide] is about 0.0003 or 0.0004% of the atmosphere…it is not a climate heat driver…when the Earth had extraordinarily larger amounts of carbon dioxide in the atmosphere, we had an ice age and there were no human beings here…They [climate scientists] thought in the 1970s we were going to have a new ice age.”",,"A recent video published on CBN News’ Facebook page alleges that carbon dioxide is not responsible for driving contemporary global warming. Jerome Corsi, a former political scientist with a history of promoting unfounded conspiracy theories, claims that carbon dioxide is a “trace element” in Earth’s atmosphere and not a “climate heat driver.” Corsi goes on to argue that “when the Earth had extraordinarily larger amounts of carbon dioxide in the atmosphere, we had an ice age and there were no human beings here.” According to Corsi, carbon dioxide has been unjustifiably “picked on” as a driver of global warming by environmental activists and political figures. He also claims that, in the 1970s, climate scientists were warning of “global cooling” rather than global warming. It is true that carbon dioxide is a minor constituent of Earth’s atmosphere by percentage. However, it is just above 0.04% today, while Corsi falsely claims carbon dioxide represents 0.0003 to 0.0004% of the atmosphere. Importantly, though, the relatively low percentage weight of atmospheric carbon dioxide does not indicate that its role in regulating climate is negligible. As James Renwick, a climate scientist at Victoria University of Wellington, notes, “carbon dioxide is the major ‘climate heat driver,’ in terms of the radiation budget of the planet.” Indeed, a consensus of scientific evidence[1,2] indicates that contemporary global warming is caused by human emissions of carbon dioxide and other greenhouse gases. This finding is also substantiated by various national and international climate reports such as the U.N. International Panel on Climate Change (IPCC) Sixth Assessment Report[3] and U.S. Fourth National Climate Assessment[4]. Carbon dioxide is a greenhouse gas – a type of gas that prevents heat from leaving the atmosphere and warms the Earth. “There are other gases that are more effective than carbon dioxide at absorbing and re-radiating heat (e.g. methane), but carbon dioxide wins in the long term because of its long lifetime of hundreds to thousands of years,” says Renwick. In addition to its long atmospheric residence time, or the amount of time a carbon dioxide molecule remains in the air, it also constitutes a majority of total greenhouse gas emissions. As such, carbon dioxide is in fact responsible for most of the warming observed since the mid 20th century (Fig. 1). Figure 1. Time series of effective radiative forcing (warming) caused by various mechanisms. Note that carbon dioxide (gray) contributes more to warming than all of the other well-mixed greenhouse gases (WMGHG). Note also that the majority of warming is caused by carbon dioxide and other greenhouse gases. Source: U.S. Fourth National Climate Assessment. While 0.04% of the atmosphere may seem small, it is important to note that carbon dioxide comprised less than 0.03% of the atmosphere prior to the onset of human emissions during the industrial revolution (Fig. 2). This change represents a dramatic departure from natural changes in atmospheric carbon dioxide, which typically varied between approximately 0.02% (200 ppm) to 0.03% (300 ppm) during the last 800,000 years and changed over periods of tens of thousands of years. Figure 2. Atmospheric carbon dioxide concentration over the last 800,000 years. Note that modern levels of >400 ppm (>0.04%), driven by anthropogenic emissions, are a rapid departure from natural variability. Source: NASA. But what about temperature over this period? Corsi claims that we had an “ice age” under “larger amounts of carbon dioxide.” While he does not invoke a specific example in Earth history, paleoclimate research has found that Earth’s glacial-interglacial cycles, periods of relative cooling (ice growth) and warming (ice melt), have indeed occurred in concert with changes in atmospheric carbon dioxide (Fig. 3), at odds with Corsi’s claim. Figure 3. Atmospheric carbon dioxide (top) and temperature change (bottom) over the last 800,000 years. Note that high levels of carbon dioxide are associated with high temperatures and low levels of carbon dioxide are associated with low temperatures. Source: Time Scavengers. Carbon dioxide is, however, just one of many climate forcing mechanisms. For example, while glacial-interglacial changes do correspond to changes in carbon dioxide, they also correspond to changes in Earth’s orbit and tilt. As such, explanations for what drives glacial-interglacial variations typically invoke a synergy of different mechanisms, including changes in Earth’s orbit, ocean circulation and atmospheric greenhouse gases[5,6,7]. Looking further back in time, paeloclimate research also generally supports a relationship between atmospheric carbon dioxide concentration and Earth’s surface temperature over the last 66 million years[8] (Fig. 4). Figure 4: Reconstructed changes in Earth’s surface temperature (top) and atmospheric carbon dioxide (bottom) over the last 66 million years. Source. Such associations do not necessarily indicate that carbon dioxide was always the main mechanism regulating changes in climate, particularly at periods in Earth’s more distant geological past. “If you go back far enough, over 100 million years ago, you can find periods where it looks as though there were high carbon dioxide levels and cool temperatures, though again the uncertainties are large,” says Renwick. “At those times though, many things were very different, such as the distribution of continents and ocean on the planet, the amount of volcanic activity (blocking out sunlight), and the brightness of the sun. Carbon dioxide is very important for the energy budget of the Earth, but it is not the only factor on very long time scales.” It is, however, misleading to invoke drivers of geological-scale climate change in order to discredit the driving role of carbon dioxide in modern climate change. Climate scientists from different disciplines have evaluated the influence of all modern climate forcing mechanisms and have repeatedly and consistently concluded that greenhouse gases are the dominant cause[3]. This is not the only misleading argument made by Corsi. He goes on to claim that climate scientists in the 1970s were warning that “we were going to have a new ice age.” This claim is commonly repeated in climate contrarian circles in an effort to undermine the reliability of climate scientists. However, a survey[9] of the climate literature between 1965 and 1979 found that only 7 studies projected future cooling. By contrast, 44 studies projected warming. Climate science has evolved dramatically since the 1970s and all of the available scientific evidence continues to support projected warming driven by human emissions of greenhouse gases[3]. Scientists’ Feedback: James Renwick Professor, Victoria University of Wellington: Jerome Corsi is right that carbon dioxide is a minor element of the atmosphere, it currently makes up around 0.04% of the air (this is however more than he claims). However, it is crucially important for regulating earth’s energy budget and surface temperatures. But he is not right about much else. Carbon dioxide is the major ‘climate heat driver,’ in terms of the radiation budget of the planet. There are other gases that are more effective than CO2 at absorbing and re-radiating heat (e.g. methane), but carbon dioxide wins in the long term because of its long lifetime of hundreds to thousands of years. This has been understood for a long time – the role of CO2 in warming the earth was discovered in the mid-19th century. It has not been ‘picked on’ recently by climate activists. The warming of the globe from increasing carbon dioxide concentrations in the air was first calculated in 1896. A good source on the history of the science is Spencer Weart’s book ‘The Discovery of Global Warming.’ Through the past 2.6 million years, the period of recent ice ages, carbon dioxide has gone up and down in step with temperature, bottoming out at around 180 parts per million in the depths of a “glacial maximum” and peaking at around 280 parts per million in the warmer interglacial periods. Going back further, CO2 levels were certainly higher than present, but so were temperatures (Fig. 3). As Corsi says, CO2 levels dropped from 500M or so years ago to the beginning of our ice age period 2.6M years ago. There were lots of ups and downs along the way, and the atmospheric concentration did not start at 7500 parts per million CO2, it was closer to 700ppm. It probably did go above 1000ppm over 100M years ago, but the uncertainties are large: Atmospheric carbon dioxide concentration over the last 400 million years. Source: Earth.org. In any case, in broad terms, yes, CO2 levels have dropped from the ‘hothouse conditions’ of 50 million years ago to the ‘icehouse conditions’ of the last few million years. In that period of time, temperatures have risen and fallen with CO2, as they have done through the recent ice ages (Fig. 3). With current emissions, we’ll be back at the “hothouse” level next century if we don’t take action. That would be catastrophic for humanity. If you go back far enough, over 100 million years ago, you can find periods where it looks as though there were high CO2 levels and cool temperatures, though again the uncertainties are large. At those times though, many things were very different, such as the distribution of continents and ocean on the planet, the amount of volcanic activity (blocking out sunlight), and the brightness of the sun. CO2 is very important for the energy budget of the earth, but it is not the only factor on very long time scales. The last point about the ‘ice age scare’ in the 1970s… yes, there were a few papers published in the 1970s wondering about this, after a couple of decades of slight global cooling. The media picked up on this and there were articles published in Time magazine and elsewhere talking about the possibility of an impending ice age. But, in the climate research community, the vast majority of papers published through the 1970s were about global warming, not global cooling. There’s a good discussion here[9].” References: 1 – Oreskes (2004) The scientific consensus on climate change. Science. 2 – Cook et al. (2013) Quantifying the consensus on anthropogenic global warming in the scientific literature. Environmental Research Letters. 3 – IPCC (2021) Sixth Assessment Report. 4 – U.S. Fourth National Climate Assessment, Climate Science Special Report. 5 – Denton et al. (2010) The Last Glacial Termination. Science 6 – McManus et al. (1999) A 0.5-Million-Year Record of Millennial-Scale Climate Variability in the North Atlantic. Science 7 – Raymo et al. (1997) The timing of major climate terminations. Paleoceanography 8 – Rae et al. (2021) Atmospheric CO2 over the Past 66 Million Years from Marine Archives. Annual Review: of Earth and Planetary Sciences 9 – Peterson et al. (2008) The myth of the 1970s global cooling scientific consensus. Bulletin of the American Meteorological Society"
https://science.feedback.org/review/the-sun-isnt-responsible-for-current-climate-change-contrary-claims-suspicious0bservers-ben-davidson/,Incorrect,"Suspicious0bservers, Ben Davidson, 2022-07-14","Scientists have neglected the effect of solar particles, cosmic rays, the interplanetary magnetic field and Earth's weakening magnetic field to conclude climate change is due to human activity",,Incorrect: Scientists have established that human activities are responsible for the climate change observed over the last several decades and ruled out the possible influence of the sun or Earth’s magnetic field.,"Though the sun does go through regular solar cycles, changes in its activity – or in the Earth’s magnetic field – cannot account for our planet’s observed climate change. The sun has, historically, played a role in changes to the Earth’s climate, but the rate and magnitude of the Earth’s current warming is too high to be linked to changes in the sun or Earth’s orbit. The effect of rising rates of atmospheric greenhouse gases, on the other hand, has been well established by decades of scientific research.","“They're able to blame us for climate change because they do not properly factor in the sun, how its activity has changed over the centuries…there's not one single paper in existence blaming humans for global warming which accounts for solar particles, cosmic rays, the interplanetary magnetic field and Earth's weakening magnetic field.”",,"On 14 July, 2022, YouTuber Ben Davidson published a video on his channel Suspicious0bservers which claims that the sun is at the root of the global warming that has been observed by scientists since the Industrial Revolution. Davidson, whose channel has more than 600,000 subscribers, claims that current climate science does not account for “solar particles, cosmic rays, the interplanetary magnetic field and Earth’s weakening magnetic field.” But scientists haven’t found a link between those factors and significant changes to the planet’s climate, said Georg Feulner, Deputy Head of Research Department at the Potsdam Institute for Climate Impact Research. The warming effect of greenhouse gases, on the other hand, has been well established – as is the link between human activities and Earth’s current warming.[1] “There is absolutely no doubt in the scientific community that the current climate crisis is due to human activities,” Feulner said in an email to Science Feedback. One of the factors Davidson points to as driving current rates of climate change are coronal mass ejections (CMEs), phenomena defined by NOAA’s Space Weather Prediction Center as “large expulsions of plasma and magnetic field from the Sun’s corona.” Davidson cites a 2002 paper published in the Journal of Geophysical Research: Space Physics to support his claim that the sun produced twice the number of CMEs from 1940 to 2005 as it did a century earlier. In its abstract, the 2002 study notes: “We surmise that the coronal mass ejection (CME) rate for recent solar cycles was approximately twice as high as that for solar cycles 100 years ago.”[2] Ian Richardson, a research scientist at NASA and the University of Maryland College Park and lead author of the 2002 study, told Science Feedback that that statement was a hypothesis of his – and, looking back on it now, probably an incorrect one. “This was really just one hypothesis that I was considering to explain (unsuccessfully) the increase in geomagnetic activity in the first part of the 20th century, and is based on the simplest assumption that the CME rate is proportional to the sunspot number as suggested by studies published at that time based on direct observations of CMEs first available in the 1970s,” Richardson said in an email. “It is unreasonable to suggest that it’s an established fact as in the video.” Coronal mass ejections aren’t associated with measurable changes to Earth’s temperature, because the magnetic field surrounding the Earth reflects the massive energy that CMEs put out back into space. This magnetic field, as NASA notes, “shields us from erosion of our atmosphere by the solar wind (charged particles our Sun continually spews at us), erosion and particle radiation from coronal mass ejections (massive clouds of energetic and magnetized solar plasma and radiation), and cosmic rays from deep space.” Davidson, however, claims that a weakening of the Earth’s magnetic field has made it easier for the sun’s energy to warm the planet. According to NASA, Earth’s magnetic field has weakened by about 9 percent on average in the last 200 years – but “paleomagnetic studies show the field is about as strong as it’s been in the past 100,000 years, and is twice as intense as its million-year average.” And scientists don’t have reason to believe that, as Davidson claims, the Earth’s poles will be flipping anytime soon: Pole reversals take place over hundreds to thousands of years, and there is no guarantee that the Earth’s current magnetic field will continue weakening.[3] “CMEs are short-lived events, and there is no evidence that the charged particles released from CMEs have a significant effect on the global climate, irrespective of the state of the Earth’s magnetic field,” Feulner said. Davidson also points to a graph of the last four centuries of sunspot observations as evidence that the sun is playing a major role in current observed climate change. Sunspots are locations on the sun’s surface that are cooler than the rest of the sun, and their number tends to vary in approximately 11-year cycles. When sunspot activity is at a maximum, there tends to be a small increase in the sun’s energy output. But that output isn’t associated with major temperature changes: According to NOAA Climate.gov, scientists estimate that slight increases in levels of sunlight between the late 1800s and mid-1900s contributed to up to 0.1°C at most of the planet’s 1.0°C of warming since the pre-industrial era. “The fact that solar activity based on the sunspot number has been falling during the last four ~11 year solar cycles might pose a problem for those who are arguing for a relation between global warming and solar activity, in that warming continues to increase,” Richardson said. “Seemingly dramatic variations in say the sunspot number, and related phenomena such as the rate of CMEs do not then result in major influences on the Earth – just large changes in a very small component of the energy input.” Figure 1 – Graph shows sunspot numbers from 1700 – present. Courtesy Ian Richardson (Credit: Royal Observatory of Belgium). Contrary to Davidson’s claims, scientists have evaluated the sun’s potential impact on climate change and found that it is dwarfed by the impact of human activities. A 2016 study concluded that, of the tests done to determine solar activity’s impact on observed climate change, “all indicate that the contribution of changing solar activity either through cosmic rays or otherwise cannot have contributed more than 10% of the global warming seen in the twentieth century.”[4] Solar radiation accounts for “more than 99.9% of the energy entering Earth’s system,”[5] and climate models do take into account for total solar irradiance – the amount of solar energy the Earth receives – as does the IPCC. According to NASA: “Since 1750, the warming driven by greenhouse gases coming from the human burning of fossil fuels is over 50 times greater than the slight extra warming coming from the Sun itself over that same time interval.” Aside from TSI, the sun also emits energetic particles, including galactic cosmic rays, which were at one point hypothesized to influence cloud formation and thus global temperature. However, research has determined that galactic cosmic rays aren’t strongly tied to cloud formation.[6-8] Figure 2 – Comparison of the global surface temperature changes (red) and the Sun’s energy that Earth receives (yellow) in watts per square meter since 1880. One can see that since the 1960s, the global temperature and solar activity have varied in opposite directions. Source: NASA/JPL-Caltech One of the reasons scientists know the sun is not responsible for our current observed warming is the rate and magnitude of our current warming is too high to be linked to changes in the sun or Earth’s orbit. Additionally, if the sun were responsible for climate change, scientists would expect to see warming from the surface of the Earth up to the stratosphere (the Earth’s second layer of atmosphere). Instead, records show that the Earth’s surface is warming, while the stratosphere is cooling. Scientists’ Feedback: The statements quoted below are from the video; comments are from the reviewers (and are lightly edited for clarity). “It wasn’t just the sun spots, it was the coronal mass ejections. The sun pounded out twice the CMEs that it was producing just a century earlier. Not only did the sun give us much more over the last century but it had an easier time getting in. Earth’s magnetic field is weakening and its poles are shifting.” Georg Feulner Senior Scientist, Potsdam Institute for Climate Impact Research (PIK):The changing number of Sun spots are an indicator of solar activity. Climate studies looking at the historic and future evolution of Earth’s climate take the small changes in the Sun’s brightness due solar activity into account, but it is scientifically well established that their impact on the global mean temperature is only a few tenths of a degree, much less than the observed global warming of currently more than one degree. Moreover, solar activity and global warming show opposing trends over the last few decades: While solar activity has been decreasing overall, global temperatures are rising quickly. CMEs are short-lived events, and there is no evidence that the charged particles released from CMEs have a significant effect on the global climate, irrespective of the state of the Earth’s magnetic field. Climate studies that tie current climate change to human activities do not account “for solar particles, cosmic rays, the interplanetary magnetic field and Earth’s weakening magnet field in the modern pole shift.” Georg Feulner Senior Scientist, Potsdam Institute for Climate Impact Research (PIK):Climate studies do not have to take these effects into account because science could not find a link between these effects and significant changes in the Earth’s climate. In contrast, the warming effect of greenhouse gases like carbon dioxide is known since the 19th century, is known to hold over Earth’s long history and can fully explain the observed warming (in combination with the other greenhouse gases, aerosols, changes in land use as well as all natural climate forcings like volcanic eruptions and changes in solar activity). There is absolutely no doubt in the scientific community that the current climate crisis is due to human activities. Ian Richardson Research Scientist, NASA/University of Maryland:I had actually forgotten about the comment that the coronal mass ejection rate might have been around twice as large now than at the beginning of the 20th century in my 2002 paper. This was really just one hypothesis that I was considering to explain (unsuccessfully) the increase in geomagnetic activity in the first part of the 20th century, and is based on the simplest assumption that the CME rate is proportional to the sunspot number as suggested by studies published at that time based on direct observations of CMEs first available in the 1970s. Because of the lower sunspot number at the beginning of the 20th century, this might suggest that the CME rate was decreased then by ~50%. But there were no observations of CMEs or the solar wind at that time and so no direct proof that this hypothesis is correct or not. On the other hand, the last solar cycle (2008-19) was the smallest in 100 years (see below) and we can compare directly the CME rate observed by spacecraft in this and the previous stronger cycle. For example, Zhang et al. (2021, Progress in Earth and Planetary Science (2021) 8:56 https://doi.org/10.1186/s40645-021-00426-7) show that the CME rate in cycle 24 was not as low as would be expected based on the lower sunspot number (see their Figures 5a and 6a). This suggests that my simple assumption that the low sunspot number at the start of the 20th century might imply a ~50% lower CME rate then was probably incorrect, and is not supported by recent CME observations. Certainly, it is unreasonable to suggest that it’s an established fact as in the video. Of course, the fact that solar activity based on the sunspot number has been falling during the last four ~11 year solar cycles (see above), might pose a problem for those who are arguing for a relation between global warming and solar activity, in that warming continues to increase. I suppose in the video, this would be accounted for by the claimed “30 year delay” in the influence of the Sun on global warming, such that the effect of the reduced solar activity in recent decades is not yet showing up in the climate record. This figure also shows nicely the known ~100 year periodicity in solar activity (e.g., smaller activity cycles tends to occur around the start of each century). Another point to bear in mind is that identifying long-term trends in the sunspot number, as in the video, is problematic. Observations of sunspots have been made over centuries by different observers with different instruments and different ways of counting sunspots (e.g., do you count every small sunspot or not?), so the sunspot record is extremely uneven. There has been a huge effort in recent years to unearth observatory records and previously unknown observations and try to adjust for these different influences (for details see https://sidc.be/silso/newdataset). The plot above is the currently accepted best estimate of the history of the sunspot number, whereas so far as I can tell, the video uses the “old” number without the corrections. This is convenient because it gives the impression that the sunspot number in the 20th century is larger than in previous centuries, but that’s largely because observing techniques were improved. In the above plot, the solar cycles in each century are much more even, and those in the 20th century aren’t especially larger than those in previous centuries. Also note that there are typical sized cycles in the 1700s following the Maunder minimum highlighted in the video which are not evident in the plot in the video. Of course, the climate deniers would probably claim this reassessment of the sunspot number is all a fraud to cover up the large cycles in the 20th century, but I know firsthand that this has been a large undertaking by an international team that are simply interested in learning more about the physics of our star, not to satisfy the climate change community. The conclusions using the longer-term reconstructed sunspot number shown in the video are probably also suspect. Yes, it does suggest that the sunspot number is currently the highest it has been for a long period, but that’s the only true data point we have. Any other conclusions depend on the accuracy of the assumptions made to reconstruct the sunspot number series (why can deniers hold the results of certain studies as facts but claim others as fraud when all science has uncertainty?). The supposed neglect of effects such as CMEs, solar particles, cosmic rays, etc. on climate change is first that they are only minor direct energy inputs into the Earth system compared to direct visible/infrared radiation. The video does highlight studies showing solar variability, and there is no dispute that this is a real phenomenon (as in the above figure). However, seemingly dramatic variations in say the sunspot number, and related phenomena such as the rate of CMEs do not then result in major influences on the Earth – just large changes in a very small component of the energy input. The effects, such as geomagnetic storms, can be dramatic but are also short term, lasting just a few hours or days and hence not an obvious contributor to long-term variations. In contrast, the much larger energy input at visible wavelengths varies only slightly over the sunspot cycle. However, the Sun, solar wind, solar energetic particles and cosmic rays do produce effects in the Earth’s magnetic field, radiation belts, ionosphere, thermosphere and troposphere (where weather occurs), and it has become increasingly clear from recent research that phenomena in these regions are strongly coupled in complex ways. There is a lot of ongoing research in this area, and it is possible that there are subtle ways in which the Sun influences climate via coupled processes in these regions. So rather than the effects of the Sun being neglected, they are being actively studied, but until the pathways by which these effects might occur are identified and assessed (including the possible influence of changes Earth’s magnetic field, which are well recognized and can be taken into account), it is not possible to consider including them in climate models. There is probably also some reluctance on the part of the climate change community to consider ideas that are from a different perspective using different science and methods/models, but I do see encouraging signs of collaboration that may shed further insight into this question e.g. at American Geophysical Union meetings. References: [1] IPCC (2021) Climate Change 2021: The Physical Science Basis. Contributions of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. [2] Richardson et al. (2002) Long-term trends in interplanetary magnetic field strength and solar wind structure during the twentieth century. Journal of Geophysical Research: Space Physics [3] Nilsson et. al (2022). Recurrent ancient geomagnetic field anomalies shed light on future evolution of the South Atlantic Anomaly. Proceedings of the National Academy of Sciences [4] Sloan et. al (2016) Cosmic rays, solar activity and the climate. Environmental Research Letters. [5] Dudok de Wit et al. (2018) Better data for modeling the Sun’s influence on climate. Eos. [6] Pierce and Adams (2009) Can cosmic rays affect cloud condensation nuclei by altering new particle formation rates? Geophysical Research Letters [7] Agee et al (2011) Relationship of Lower-Troposphere Cloud Cover and Cosmic Rays: An Updated Perspective. Journal of Climate [8] Dunne et al (2016) Global atmospheric particle formation from CERN CLOUD measurements. Science"
https://science.feedback.org/review/warming-earths-surface-oceans-continues-apace-contrary-to-claims-daily-sceptic-chris-morrison/,Incorrect,"Daily Sceptic, Chris Morrison, 2022-05-19",”Global warming started to run out of steam over two decades ago… Half of the apparent global temperature increase from January 1910 to January 2000 is due to administrative adjustments.”,,"Incorrect: Continuous warming of the Earth’s surface and oceans has been measured since the 1960s by multiple independent and peer-reviewed datasets. All of the available evidence indicates that global warming has not stopped, with 2016 and 2020 being the warmest years on record. Ocean heat content data also indicate an increase from 1998 to 2012.Misleading:  Adjustments to the NASA GISS surface temperature dataset are made to accommodate new stations and updated algorithms. When adjusted annual temperature data from NASA GISS are compared against raw temperature data, the adjusted dataset actually diminishes the warming trend from ~1940 to present.","Global warming has been a persistent signal in all relevant climate datasets from ~1960 to present. The 1998 to 2012 interval has received attention by climate contrarians due to an apparent warming slowdown in surface temperature datasets, which may be due to a combination of natural and internal variability as specifically noted in the Intergovernmental Panel on Climate Change’s Sixth Assessment Report. However, warming did occur throughout this interval and continues to the present day as shown in measurements of surface temperature, ocean heat content, glacier melt and sea-level rise. ","”In a major re-evaluation of data from meteorology balloons rising through the troposphere, the scientists confirmed that temperatures have mostly paused since around 1998. In July 2013, the Met Office published a paper about the [1998 to 2012] pause, although its main argument that the heat had disappeared into the ocean does not seem to have stood the test of time. Professor Humlum looked at the adjustments to the NASA GISS [surface temperature] dataset and found that ‘half of the apparent global temperature increase from January 1910 to January 2000 is due to administrative adjustments to the original data since May 2008.’”",,"In a recent article in the Daily Sceptic, a website with a history of publishing scientifically unfounded claims, Chris Morrison repeats a common claim in contrarian circles that “global warming has slowed dramatically” since 1998. Morrison, who presents himself as a former financial journalist, further goes on to downplay past warming, claiming that “half of the apparent global temperature increase from January 1910 to January 2000 is due to administrative adjustments to the original [NASA Goddard Institute for Space Studies (GISS) surface temperature] data since May 2008”. This claim that global warming is due to data adjustment has been shown false in the past, as re-explained below. Temperature corrections are made to accommodate new stations and updated algorithms used to produce the dataset, says Gavin Schmidt, a climate scientist and director of GISS. Schmidt also notes that changes in temperature among different versions of the dataset are “very small compared to the changes over time because of climate” (Fig. 1). Moreover, the corrections applied to the NASA GISS dataset actually reduced the temperature increase from ~1940 to present, rather than accentuated it, as claimed by Morrison (Fig. 2). Figure 1. Different versions of the GISS global mean temperature time series. Note that the small adjustments to the dataset invoked by Morrison are not sufficient to negate the clear warming trend. Source: NASA GISS.Figure 2. NASA GISS adjusted temperature anomalies (teal) compared to raw unadjusted data (black). Note that the adjustments made to the GISS time series suppress the warming trend since ~1940, rather than accentuate it as claimed by Morrison. Source: NASA Climate.Then how did Morrison and Ole Humlum, a geographer at the University of Oslo quoted in the article, conclude that these corrections resulted in much larger impacts on the final dataset when comparing temperatures for January 1910 and January 2000? “This is just a cherry pick,” says Schmidt. “There is a lot of noise in the monthly data, and this particular comparison is just the largest adjustment he could find. If he had looked at January 1881, the adjustments reduced the difference to Jan 2000 by about 0.1 ºC.” “Regardless of what record you look at, [warming] trends have continued through 1998. In all records, 2016 or 2020 were the warmest years on record,” says Schmidt (Fig. 3). Continued warming is indeed reinforced by findings from the latest national and international climate reports such as the U.S. National Climate Assessment[1], the Intergovernmental Panel on Climate Change’s Sixth Assessment report (IPCC AR6)[2], the American Meteorological Society’s State of the Climate in 2020 report[3]and the World Meteorological Organization’s State of the Global Climate 2021 report[4]. The available evidence is therefore in clear contrast to Morrison’s claim that “temperatures have mostly paused since around 1998.” Figure 3. Temperature anomalies from different datasets since the late 1970s. Note that the warming trend continues from 1998 to present, in clear contrast to claims made by Morrison. Source: RealClimate.Fabio Madonna, an atmospheric scientist at the Italian National Research Council and lead author of the study[5]invoked by Morrison, agrees with Schmidt. “In my paper, it is never mentioned that temperatures have mostly paused since around 1998,” says Madonna. “The analysis of the time series of upper-air data shows that in 1998 something happened (likely boosted by a strong El Niño [a shift in Pacific Ocean circulation patterns that impacts temperature records[6]]) with a slow down of the warming of the upper troposphere in the northern hemisphere only.” There are therefore two major problems with Morrison’s argument: first, it relies exclusively upon data from the upper troposphere in only a portion of the northern hemisphere, which is not representative of global climate trends. As Victor Venema, a climate scientist at the University of Bonn, says, “[Morrison’s] ‘evidence’ seems to be his own eye-ball estimate of warming for a small part of the Earth, the air 9-km up in the northern hemisphere between 20 and 70 °N, which is not global. Compared to the actual global temperature this would be missing the strong warming we have recently seen in the Arctic.” Secondly, using 1998 as a starting point is problematic, note climate scientists Andrea Steiner and Stephen Po-Chedley. “The positive temperature anomalies due to the strong El Niño leads to a trend dominated by this large peak,” says Steiner. Thus, Morrison’s reliance upon this time period is an example of cherry picking: selectively picking a particularly warm year as a baseline in order to downplay the warming trend. Morrison continues to write that the Met Office’s “main argument that the heat [from 1998 to 2012] had disappeared into the ocean does not seem to have stood the test of time.” Morrison’s claim, however, is again in contradiction with ocean heat content data published by NOAA that show continuous warming of the upper 700 meters of the ocean since ~1990 (Fig. 4).Figure 4. Time series of ocean heat content (upper 700 m). Note that the positive trend continues from 1998 to 2012, in contrast to Morrison’s claims of a warming “pause”. Source: NOAA.Further, the IPCC AR6[2]provides specific comments on this particular interval, noting that the slower increase in surface temperature, “was a temporary event induced by internal and naturally-forced variability that partly offset the anthropogenic warming trend over this period. Nonetheless, the heating of the climate system continued during this period, as reflected in the continued warming of the global ocean (very high confidence) and in the continued rise of hot extremes over land (medium confidence).”Annotations: The statements quoted below are from the article; comments are from the reviewers (and are lightly edited for clarity). Daily Sceptic claim: “Temperature [increase] has mostly paused since around 1998” Gavin Schmidt Director, NASA Goddard Institute for Space Studies: Not true. Regardless of what record you look at (satellite or surface or reanalyses (like ERA5)), trends have continued through 1998. In all records, 2016 or 2020 were the warmest years on record (see Fig. 3).Andrea Steiner Professor for Climate Analysis and Director, Wegener Center for Climate and Global Change, University of Graz, Austria: This is a misleading statement. Using 1998 as a starting point with the positive temperature anomalies due to the strong El Niño leads to a trend dominated by this large peak. Current best estimates of atmospheric temperature trends have been published in several peer-reviewed journals and assessed by the recent IPCC 6th Assessment Report[2]of WG I. Chapter 2 of the report shows the observed changing state of the climate system. Fig. 2.12 shows atmospheric temperature trends. Temperature increase has definitely not paused, the troposphere has been warming (Table 2.5). For more information and also surface trend estimates see chapter 2.3.1.Fabio Madonna Scientist, Italian National Research Council: The IPCC AR6 considered the totality of evidence to conclude that the troposphere has warmed since at least the 1950s. In the tropics, the upper troposphere has warmed faster than the near-surface temperatures since at least 2001. This is the most general view agreed by the scientific community. In my JGR paper[5], it is never mentioned that “temperatures have mostly paused since around 1998.” The analysis of the time series of upper-air data shows that in 1998 something happened (likely boosted by a strong El Niño) with a slow down of the warming of the upper troposphere in the northern hemisphere only. Moreover, the results at 300 hPa in the tropics show, instead, a significant warming after 2000 at 300 hPa in line with the statements by IPCC. After 2015 the warming has largely sped up globally: this is also accompanied by an increase of relative humidity in the southern hemisphere (again likely boosted by another strong El Niño). This is also commented on in my paper. The last 5-6 years of strong warming are also reported in several bulletins and journal papers. The warming/cooling in the upper-troposphere is not immediately related to the near surface temperature trends: if from one side there is a correlation among different vertical regions in the atmosphere, from another side it is also true that changes are reflected in each region with different “sensitivities”. For example, in the JGR paper, where I do not investigate any near surface temperature data, I show that at 300 hPa in the Northern Hemisphere, the decadal temperature trend in the period 1978 – 2018 is 10-20% smaller than the trends at 850 hPa (about 1.5 km of altitude), while in the tropics the warming trend at 300 hPa is 40-50 % larger than the trend at 850 hPa. Investigating trends is a very delicate task because uncertainties affecting the trend estimation are very often larger than the trend themselves. Moreover, the interpretation of trends values must be seen in a global context and over a long time period to ensure that the data analysis may clearly reveal the “fingerprints” of climate change.Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: First, the Earth is warming due to anthropogenic emissions of greenhouse gases. The rate of warming is influenced by natural variations in the Earth’s climate (e.g., volcanic eruptions and El Niño events). Consideration of longer time periods reduces the impact of natural variations in Earth’s climate on anthropogenic warming. Choosing a starting point of 1998 is cherry picking and misleads readers (there was a large El Niño over 1997 – 1998). Second, despite the above disclaimer, it is not true that temperature changes have paused since around 1998. Across all lower tropospheric datasets (UAH, RSS, ERA5, JRA-55, RATPAC, RICH, and RAOBCORE) used in the State of the Climate Report[3](the peer-reviewed version, not the version by the Global Warming Policy Foundation think tank cited in the article) there is warming over 1998 – 2021. On average, the post-1998 warming is 0.22 K per decade (with a range of 0.11 – 0.30 K per decade across datasets). Note that other papers that consider radio occultation measurements (available over 2002 – 2018) also show rapid tropospheric warming[7]. The new dataset and publication cited by the Daily Sceptic did not analyze the period after 1998 and does not purport that temperature change has paused.Victor Venema Scientist, University of Bonn, Germany: This is not supported by the evidence. For example the recent IPCC report shows consistent warming over the last 4 to 5 decades. See figure below, which is Figure 2.11c from the IPCC (2021) report[2]: The only new information the article presents is not about global warming, which normally points to the warming of the surface temperature, but about the upper air temperature (around 9 km up in the air). And the “evidence” is only one dataset of many. The upper air temperature is valuable for many applications, but a much less reliable source for long-term trend computations. Measuring upper air temperature is much harder and instruments change regularly. It uses one-way instruments, which need to have a dynamic range of up to 100 °C, operate in clouds and with little ventilation in harsh sunlight. Also radiosondes are mostly launched over land and the data is really spare for the Southern Hemisphere. The article cites this new radiosonde dataset with upper air temperature data to claim “Further scientific evidence that global warming starting to run out of steam over two decades ago has been presented by an international group of leading scientists.” However, the article does not make any claims about slowing warming in the last 20 years. It even makes the opposite claim about the tropics: “For temperature (Figure 8) in the [Northern Hemisphere], IGRA, RHARM [The new dataset of this study], and ERA5 show a similar positive trend of 0.38, 0.39 and 0.43 K da −1 [that is degree per decade], respectively, while in the tropics at 300 hPa the trend is of 0.17, 0.25, 0.20 K da −1, with a more pronounced trend increase starting around 1997.” Chris Morrison shows a plot from the study. Thus his actual “evidence” seems to be his own research eye-ball estimate of warming for a small part of the Earth, the air 9-km up in the Northern Hemisphere between 20 and 70 °N, which is not global. Compared to the actual global temperature this would, e.g., be missing the strong warming we have recently seen in the Arctic.Daily Sceptic claim: “Professor Humlum looked at the adjustments to the NASA GISS dataset and found that ‘half of the apparent global temperature increase from January 1910 to January 2000 is due to administrative adjustments to the original data since May 2008’” Gavin Schmidt Director, NASA Goddard Institute for Space Studies: This is just a cherry pick. There is a lot of noise in the monthly data, and this particular comparison is just the largest adjustment he could find. If he had looked at Jan 1881, the adjustments reduced the difference to Jan 2000 by about 0.1ºC. But all of these adjustments – which happen because we’ve added stations, updated algorithms etc. – are very small compared to the changes over time because of climate (Fig. 2).Victor Venema Scientist, University of Bonn, Germany: The term “administrative adjustments” is not used in science and comes from a report Humlum wrote for an anti-science Think Tank, the Global Warming Policy Foundation [GWPF]. This computation does not make much sense, but the same graph could have been used to claim that there was effectively no change in the “administrative adjustments” over the full period of the dataset. So even if the measure made sense, the claim would be a misleading cherry pick of a specific period. The claim seems to correspond to the often used conspiracy theory that an open group of thousands of scientists from all over the world and numerous disciplines are conspiring against humanity by pretending that the world warms more than it actually warms. An inconvenient fact for this conspiracy, which is normally not mentioned by people making the claim, is that the “homogenization adjustments” scientists make result in a smaller global warming estimate than the one one would make based on raw data without adjustments[8] (see Fig. 2). Had it been the other way around, it would still not have been sufficient to call it suspicious. Also, then it would have required an engagement with the science, the published reasons for the adjustments and the published evidence they make the warming estimates more accurate.Andrea Steiner Professor for Climate Analysis and Director, Wegener Center for Climate and Global Change, University of Graz, Austria: Data records are continuously reprocessed and subject to improved quality control. There are several different groups that produce surface data sets, reaching similar conclusions while using different methods. The mentioned State of the Climate report of Prof Humlum [written for the GWPF] is not an independently peer-reviewed report according to scientific standards. The original “State of the Climate” report is an international peer-reviewed report in BAMS [Bulletin of the American Meteorological Society], written by dozens of scientists[3].The most recent report on the year 2021 is still under peer-review. There is also the “State of the Global Climate” report by the World Meteorological Organization (WMO)[4].Daily Sceptic claim: The argument that the heat [from 1998 to 2012] had disappeared into the ocean does not seem to have stood the test of time Gavin Schmidt Director, NASA Goddard Institute for Space Studies: The change of ocean heat is tracked by NOAA and sees continuous increases over this time (Fig. 4).Andrea Steiner Professor for Climate Analysis and Director, Wegener Center for Climate and Global Change, University of Graz, Austria: See the statement below from Chapter 3 of the IPCC AR6 WGI[2], Cross Chapter Box 3.1: “With updated observation-based GMST [Global Mean Surface Temperature] datasets and forcing, improved analysis methods, new modelling evidence and deeper understanding of mechanisms, there is very high confidence that the slower GMST and GSAT [Global mean Surface Air Temperature] increase inferred from observations in the 1998–2012 period was a temporary event induced by internal and naturally-forced variability that partly offset the anthropogenic warming trend over this period. Nonetheless, the heating of the climate system continued during this period, as reflected in the continued warming of the global ocean (very high confidence) and in the continued rise of hot extremes over land (medium confidence). Considering all the sources of uncertainties, it is impossible to robustly identify a single cause of the early 2000s slowdown[9,10]; rather, it should be interpreted as due to a combination of several factors.[11,12,13]”References: 1 – U.S. National Climate Assessment (2018). Fourth National Climate Assessment. 2 – IPCC (2021). Sixth Assessment Report. 3 – American Meteorological Society (2021). State of the Climate in 2020. 4 – World Meteorological Organization (2021). The State of the Global Climate. 5 – Madonna et al. (2021). The New Radiosounding HARMonization (RHARM) Data Set of Homogenized Radiosounding Temperature, Humidity, and Wind Profiles With Uncertainties. JGR Atmospheres. 6 – NOAA (2016). El Niño and La Niña: Frequently asked questions. 7 – Steiner et al. (2020). Observed Temperature Changes in the Troposphere and Stratosphere from 1979 to 2018. Journal of Climate. 8 – Karl et al. (2015). Possible artifacts of data biases in the recent global surface warming hiatus. Science. 9 – Hedemann et al. (2017). The subtle origins of surface-warming hiatuses. Nature Climate Change. 10 – Power et al. (2017). Apparent limitations in the ability of CMIP5 climate models to simulate recent multi-decadal change in surface temperature: implications for global temperature projections. Climate Dynamics. 11 – Huber and Knutti (2014). Natural variability, radiative forcing and climate response in the recent hiatus reconciled. Nature Geoscience. 12 – Schmidt et al. (2014). Reconciling warming trends. Nature Geoscience. 13 – Medhaug et al. (2017). Reconciling controversies about the ‘global warming hiatus’. Nature."
https://science.feedback.org/review/earths-surface-warm-due-greenhouse-gas-christopher-monckton-watts-up-with-that/,Incorrect,"Watts Up With That?, Christopher Monckton, 2022-04-04","“...Seven and a half years have passed since there was any trend in global warming at all” If global warming was caused by human emissions, temperature would rise at a steady rate",,"Incorrect: Global warming describes the long-term increase in global average surface temperature due mainly to human emissions of greenhouse gasses that trap infrared radiation. Short-term fluctuations around that trend due to natural variability are observed, but it is incorrect to conclude that the Earth’s current long-term warming trend is due to natural processes such as El Niño events.   Misleading: Monckton claims that there has been a “pause” in global warming since 2015 based on a surface temperature dataset. This claim ignores that global warming continues, as documented in datasets of ocean heat content, global ice cover and sea-level rise among other sources.","To accurately measure global warming, it is necessary to look at all of the available evidence over several decades. A popular technique of climate science contrarians is to focus on short timescales during which surface temperatures reflect interannual variability in order to mask the overall warming trend observed in numerous climate datasets over the last several decades. Taken together, the evidence suggests that the rate of global warming has actually increased, not paused.","“...Seven and a half years have passed since there was any trend in global warming at all”  “[Temperature] has been rising in occasional spurts in response to natural events such as the great Pacific shift of 1976 and the subsequent strong El Niño events, rather than at the somewhat steadier rate that one might expect if our continuing – and continuous – sins of emission were the primary culprit.”",,"A recent article in Watts Up With That, a blog with a long history of publishing scientifically unfounded claims, authored by Christopher Monckton argues that there has not been any global warming over the last 7 and a half years. Monckton, a former British politician with formal training in classics and journalism, further claims that past increases in temperature have been caused by natural processes such as “the great Pacific shift of 1976 and the subsequent strong El Niño events”. The argument that global warming has paused or stopped is not a new one. Climate science contrarians previously made this argument over a decade ago, using an apparent warming hiatus from 1998 to 2010 in an attempt to discredit emissions-driven global warming. Such claims, which have been previously assessed and debunked by NASA climate scientist Gavin Schmidt[1], rely upon a limited selection of data and ignore the long-term warming trend in global mean surface temperature (Fig. 1). Schmidt notes that this technique is disingenuous and statistically flawed because “looking at only 8 years of data is looking primarily at the ‘noise’ of interannual variability rather than at the forced long-term trend. This makes as much sense as analyzing the temperature observations from 10-17 April to check whether it really gets warmer during spring.”[1] Monckton’s recent claim is no exception, as the author uses only 7 and a half years of surface temperature data (from 2015 to 2022) in order to cast doubt on the large consensus of scientific evidence which demonstrates that surface temperatures are warming due to human greenhouse gas emissions.[2-5]This is an example of cherry picking data, selecting only a small subset of the available data in order to advance the author’s narrative, and leads Monckton to make the erroneous claim that natural shifts in climate, such as those caused by variations in the Pacific Ocean, have been responsible for surface temperatures rising “in occasional spurts”. However, global surface temperature observations reveal an unabated increasing trend since the early 1960s (Fig. 1), with only short term fluctuations around the trend.Figure 1. Global mean surface temperature (GMST) trend over the last 170 years. Black dots represent monthly temperature observations. The yellow line represents the modeled human contribution to temperature rise whereas the blue line represents the influence of natural (non-human) variability on temperature. The red line represents the combined modeled temperature response to both human-caused and natural temperature change. The fact that temperature observations track the red line but not the blue line indicates that human activities such as greenhouse gas emissions can explain modern global warming, but natural processes cannot. Source: Globalwarmingindex.org.Robert Jnglin Wills, a scientist at the University of Washington who studies the role of atmospheric and oceanic circulation in climate, commented, “It is well understood that global temperature changes result from a combination of anthropogenic greenhouse gasses and internal climate variability such as El Niño [a source of natural variability in the Pacific Ocean invoked by Monckton]. Anthropogenic global warming dominates the multi-decadal trends, while internal variability is important for trends up to a few decades.” El Niño events are a part of a natural variation in Pacific Ocean circulation patterns called the El Niño Southern Oscillation (ENSO). Two phases of ENSO exist: the El Niño mode and the La Niña mode, which give rise to distinct weather conditions around the planet.[6] During an El Niño event, trade winds weaken. These winds are responsible for driving the circulation of relatively warm surface waters from South America to Asia, and so weaker winds under an El Niño event result in an accumulation of warmer surface waters in the eastern Pacific but relatively less warming in the deeper parts of the ocean. By contrast, strong trade winds characteristic of a La Niña event result in an increase in temperature in deeper parts of the western Pacific but cooler conditions at the surface. In the tropical Pacific Ocean, sea surface temperatures are therefore relatively warmer during El Niño events but relatively cooler during La Niña events (Fig. 2). Due to the enormous size of the Pacific Ocean, sea-surface temperature variations in this region strongly influence globally averaged surface temperature datasets.[6]Figure 2. Departures in sea surface temperatures from average conditions during a La Niña event in 1988 and an El Niño event in 1997. Source: NOAA.As such, it is typical for the warmest year in a given decade as recorded by surface measurements to correspond to an El Niño event whereas the coolest year in a given decade is usually associated with a La Niña event (Fig. 3). Importantly, this does not indicate that the planet gains heat during an El Niño event or loses heat during a La Niña event, but rather that there is a redistribution of heat between the deep ocean (which is warmer than average during a La Niña event) and the planet’s surface/lower atmosphere (which is warmer than average during an El Niño event).Figure 3. Annual globally averaged surface temperature separated by decade. Note that most of the warmest surface temperature years in a given decade occur during El Niño events (red dots) and that most of the coldest surface temperature years in a given decade occur during La Niña events (blue dots). This is due to the vast size of the Pacific Ocean, which strongly influences globally averaged surface temperature datasets. Source: NOAA.Despite the transient influence of these events on globally averaged surface temperature during a given year, the data clearly demonstrate an increase in surface warming regardless of ENSO activity (Fig. 2). Monckton’s claim that large El Niño events after 1976 drove recent increases in surface temperature is therefore not supported by the data. In fact, a recent study by Cheng et al. found that ocean surface temperatures actually reached another all-time high in 2021 despite the cooling effect derived from the concurrent La Niña event.[7] So, what about that “pause” in global warming over the last 7 and a half years that Monckton discusses? In the blog post, the author uses a relatively stable trend in satellite temperature measurements and the HadCRUT4 dataset, a global compilation of surface temperature data produced by the Met Office Hadley Centre and Climatic Research Unit at the University of East Anglia[8], from 2015 to present as evidence for such a pause. However, because an El Niño event occurred from 2015 to 2016, some cooling relative to 2015 is expected and so choosing this year as a baseline is problematic. As Inglis notes, the interval selected by Monckton is “…cherry-picked to maximize the cooling trend following the El Niño event relative to the long-term anthropogenic warming trend.” Further, had Monckton included data from the subsurface ocean, which stores most of Earth’s excess heat (Fig. 4), the author would have identified a relatively linear increase in warming (Figs. 4 and 5). In fact, when considering all relevant climate indicators such as ocean heat content, sea-level change and global ice cover, the World Meteorological Organization identified an acceleration in the rate of climate change from 2015 to 2019, not a pause.[9] It is therefore misleading to claim that global warming has not occurred since 2015 and Monckton’s exclusion of additional climate datasets is another example of cherry picking.Figure 4. Time series of excess energy in the ocean, land, ice and atmosphere. The vast majority of excess energy caused by global warming is stored in the upper 700 m of the ocean. Note that ocean heat content has increased since 2015, contrary to Monckton’s claim that global warming has “paused” over this period. Source: von Schuckmann et al. (2020).[10]Figure 5: Time series of global ocean heat content from 0 to 700 m depth (where most ocean heat storage occurs). Note that ocean heat content has increased linearly since 2015, contrary to Monckton’s claim that global warming has “paused” over this period. Source: NOAA.As has been documented by an overwhelming consensus of scientific evidence[2-5], anthropogenic greenhouse gas emissions are the main driver of modern global warming. This was recently verified again by the Sixth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), which states that “it is unequivocal that the increase of CO2, methane (CH4) and nitrous oxide (N2O) in the atmosphere over the industrial era is the result of human activities and that human influence is the principal driver of many changes observed across the atmosphere, ocean, cryosphere and biosphere” including global warming.[11] Monckton’s alternative conclusion that greenhouse gas emissions cannot be responsible for modern global warming is rooted in the author’s misrepresentation of equilibrium climate sensitivity, the level of global warming expected from a doubling of CO2 emissions. Citing Zelinka et al. (2020)[12], Monckton claims that climate scientists base their predictions of emissions-driven warming by first “imagining” that all warming is driven by CO2 and then back-calculating the impacts of emissions on absolute temperature. The author goes on to use an invented formula involving absolute temperature to assert that the impacts of CO2 on warming are negligible, a claim which is not supported by the scientific literature[11]. According to Wills, Monckton’s technique to recalculate emissions-driven warming is flawed because “whether it is calculated from models or observations, [equilibrium climate sensitivity] is a calculation about how the climate system responds to a perturbation away from an equilibrium state (e.g., warming in response to greenhouse gas emissions) and the absolute temperature is not a part of the calculation.” Indeed, this is true of the climate models evaluated in both Zelinka et al. (2020)[12] and the compilation of estimates from models and observations in the latest IPCC report.[11] Note that this article was updated on April 14, 2022 to include additional comments from Mark Richardson. Reviewers’ Feedback: Robert Jnglin Wills Research Scientist, University of Washington Department of Atmospheric Sciences: This article relies on cherry-picking and misconstruction of our knowledge of the climate system to argue that the role of anthropogenic greenhouse gasses in global warming has been overblown. It is well understood that global temperature changes result from a combination of anthropogenic greenhouse gasses and internal climate variability such as El Niño. Anthropogenic global warming dominates the multi-decadal trends, while internal variability is important for trends up to a few decades. The article selects a 7-year period following a large El Niño event in 2015-16, which is cherry-picked to maximize the cooling trend following the El Niño event relative to the long-term anthropogenic warming trend. It then acknowledges that cherry-picking and responds by further cherry-picking, calculating a trend back to 1850, which is muted by the weak greenhouse gas forcing prior to the 20th century, and comparing that against a somewhat high estimate of 1.8°C global warming by 2030 from the IPCC first assessment report in 1990.[13] Methods to estimate the future warming trend have improved since 1990, but this early estimate is still within the range of global temperature changes of 1.2-1.8°C (relative to 1850-1900; very likely range) that are predicted for the 20-year period 2021-2040 by the most recent IPCC report[11], showing just one example of how accurate early predictions of global warming were (one that was cherry picked because it was not as good as others). This article then goes on to misconstrue the physical understanding of global warming based on climate feedbacks, arguing that climate scientists ignore the warming of the earth by pre-industrial (non-anthropogenic) greenhouse gasses and the sun. In contrast, understanding of the role of greenhouse gasses and solar forcing in setting the pre-industrial temperature is foundational to the understanding of how much global temperature will rise in response to anthropogenic CO2 emissions.Mark Richardson Research Associate, Colorado State University/NASA JPL: This blog misleads readers with simple statistical mistakes and a discussion of climate physics that is basically gobbledygook. The latest data shows ongoing global warming[17], here is data with a statistical fit that has been shown to accurately estimate longer-term changes.[18] The 1.2 °C (2.2 °F) warming is obviously not a straight line[19], and the last decade rate is around 2.2 °C per century. The blogger mistakenly uses a straight line to claim just 0.5 °C per century recently, and also incorrectly calculates statistical uncertainties.[20] Smaller year-to-year temperature jumps are often related to the Pacific El Niño-La Niña cycle. The figure below shows global temperatures in red and an El Niño dataset in blue.El Niño spikes trigger short-term warming, like in 1997/98 and 2015/16. The blogger claims some “great El Niño shift” in 1986 that isn’t in the data, and research has found that the Pacific has not acted to accelerate warming.[21,22] The blogger begins one part of their analysis near the strong warming El Niño event of 2015/16 and ends during the recent extended La Niña event. By picking a short period with a strong El Niño-La Niña switch, the long-term trend is temporarily hidden. Notably, if you only look at years that were strongly affected by La Niña, 2021 is the warmest of them all. El Niño and La Niña events have less effect on the Earth’s heat buildup. The left panel below shows measured ocean heat, and the right panel satellite-measured sea level changes. These show clearly that global warming is continuing.The blog’s later claims about how climate models calculate climate change, with a reference to a 2020 study by Dr. Mark Zelinka and colleagues[12]and others are just detached from the reality of what those researchers did, and are so nonsensical that it’s not possible to judge them scientifically.Annotations: The statements quoted below are from the article; comments are from the reviewers (and are lightly edited for clarity). “IPCC (1990, p. xxiv) confidently predicted 1.8 K global mean anthropogenic warming from 1850-2030.”Robert Jnglin Wills Research Scientist, University of Washington Department of Atmospheric Sciences: The value quoted is the “best estimate” from that IPCC report and does not include the full range of predicted values. For example, the most recent IPCC report[11] predicts 1.2-1.8°C of global warming (relative to 1850-1900; very likely range) for the 20-year period 2021-2040, with a best estimate of 1.5°C, and 2.8-4.6°C of global warming (relative to 1850-1900; moderately high emissions scenario; very likely range) for the 20-year period 2081-2100, with a best estimate of 3.6°C. For context, the IPCC Special Report on Global Warming of 1.5°C[14] compiles evidence that extreme heat, extreme rainfall, drought, ocean acidification, and associated impacts on ecosystems and human society will be greater at 2°C of global warming than at 1.5°C of global warming. “To forestall the usual whingeing about “cherry-picking” from the climate-fanatical trolls, here is the entire HadCRUT4 record of monthly global mean surface temperature anomalies for the 172 years 1850-2021. The trend is a not particularly catastrophic half a degree per century equivalent. ” Robert Jnglin Wills Research Scientist, University of Washington Department of Atmospheric Sciences: Looking at the NASA GISTEMP observational temperature data between 1880 and 2018, Parsons et al. (2020)[15] show that 100-year trends have ranged between 0.35 °C/100 years (1880–1979) and 1.0 °C/100 years (1919-2018), with a median value of 0.69 °C/100 years. The higher trends in later periods reflect the increase in greenhouse gas emissions rate over time and show that the 0.54 °C/century reported in this article is on the lower end of what has been observed. Parsons et al. (2020)[15] also show that no climate model simulates 100-year trends as large as that observed over 1919-2018 unless they include anthropogenic greenhouse gas emissions. “For 1850, the system-gain factor, by which one multiplies a direct warming (or reference sensitivity) to allow for feedback response and derive final warming (or equilibrium sensitivity) is not, as Hansen (1984), Schlesinger (1988) or Lacis (2010, 2013) absurdly imagined, 32 / 8 = 4. Instead, it is (255 + 32) / (255 + 8) < 1.1. Their error is as elementary as that.” Robert Jnglin Wills Research Scientist, University of Washington Department of Atmospheric Sciences: This is not how the equilibrium climate sensitivity (ECS) – the global warming in response to a doubling of CO2 – is calculated. The 4°C value given in Zelinka et al. 2020[12] is calculated from a mean of multiple climate models, and the models have an ECS range of 1.8 to 5.6°C. However, the IPCC Sixth Assessment Report[11] considers multiple lines of evidence including observations and states that there is high confidence that ECS is within the range of 2.5°C to 4°C, with a best estimate of 3°C. Whether it is calculated from models or observations, ECS is a calculation about how the climate system responds to a perturbation away from an equilibrium state (e.g., warming in response to greenhouse gas emissions) and the absolute temperature is not a part of the calculation. “For every hillside is infested with whomping windmills – 14th-century technology to address a 21st-century non-problem. Birds, bees and bats by the billion are being blended or batted out of the sky.”Robert Jnglin Wills Research Scientist, University of Washington Department of Atmospheric Sciences: “The State of the Birds 2014” Report estimates that 234,000 birds per year are killed by wind turbines in the U.S. compared to 2.4 billion per year killed by cats in the U.S. and 599 million per year killed by building windows in the U.S.[16] “It will make no difference to global temperature. Even if all the nations bound by the Paris discords actually achieved net-zero emissions by 2050, as Mr Johnson fatuously proposes, the global warming abated would be little more than a twentieth of a degree, for most countries are not bound by it.” Robert Jnglin Wills Research Scientist, University of Washington Department of Atmospheric Sciences: This is misleading, because it talks about a scenario where only countries bound by the Paris Agreement reduce their greenhouse gas emissions, when the Paris Agreement is a framework for setting emissions targets and does not itself have binding emissions targets. The IPCC Sixth Assessment Report on the Mitigation of Climate Change estimates that a scenario with an 85% reduction in global greenhouse gas emissions by 2050 would reduce global warming by more than 1°C compared to a scenario with a global 5% emissions reduction by 2050 (Global Emissions Pathway Category C1 vs. C6).[11]References: 1 – Schmidt (2008). Uncertainty, noise and the art of model-data comparison. RealClimate. 2 – Oreskes (2004) The scientific consensus on climate change. Science. 3 – Anderegg et al. (2010) Expert credibility in climate change. Proceedings of the National Academy of Sciences. 4 – Cook et al. (2013) Quantifying the consensus on anthropogenic global warming in the scientific literature. Environmental Research Letters. 5 – Cook et al. (2016) Consensus on consensus: a synthesis of consensus estimates on human-caused global warming. Environmental Research Letters. 6 – NOAA (2021). El Niño and La Niña: Frequently asked questions. 7 – Cheng et al. (2021). Another Record: Ocean Warming Continues through 2021 despite La Niña Conditions. Advances in Atmospheric Sciences. 8 – Met Office (2016). HadCRUT4. Hadley Centre observations datasets. 9 – World Meteorological Organization (2019). Global Climate in 2015-2019: Climate change accelerates. 10 – von Shuckmann et al. (2020). Heat stored in the Earth system: where does the energy go? Earth System Science Data. 11 – IPCC (2022). Sixth Assessment Report. 12 – Zelinka et al. (2020). Causes of higher climate sensitivity in CMIP6 models. Geophysical Research Letters. 13 – IPCC (1990). First Assessment Report. 14 – IPCC (2018). Special Assessment Report on the Impacts of Global Warming of 1.5 °C. 15 – Parsons et al. (2020). Magnitudes and Spatial Patterns of Interdecadal Temperature Variability in CMIP6. Geophysical Research Letters. 16 – State of the Birds (2014). The State of the Birds Report. 17 – Richardson (2022). Prospects for Detecting Accelerated Global Warming. Geophysical Research Letters. 18 – Clarke and Richardson (2021). The Benefits of Continuous Local Regression for Quantifying Global Warming. Earth and Space Science. 19 – Cahill et al. (2015). Change points of global temperature. Environmental Research Letters. 20 – Thiébaux and Zwiers (1984). The Interpretation and Estimation of Effective Sample Size. Journal of Applied Meterology and Climatology. 21 – England et al. (2014). Recent intensification of wind-driven circulation in the Pacific and the ongoing warming hiatus. Nature Climate Change. 22 – Zhou et al. (2016). Impact of decadal cloud variations on the Earth’s energy budget. Nature Geoscience."
https://science.feedback.org/review/robust-scientific-evidence-supports-human-activity-drives-global-warming-contrary-to-claims-co2-coalition-blog-post-andy-may/,Incorrect,"CO2 Coalition, Andy May, 2022-03-03","""There is no evidence, other than models, that human CO2 emissions drive climate change and abundant evidence that the Sun, coupled with natural climate cycles, drives most, if not all, of recent climate changes""",,"Incorrect: Solar irradiance has had a negligible impact on Earth’s climate since the industrial era. Atmospheric observations do not support the hypothesis that the Sun has driven modern warming. There is a consensus of scientific evidence that warming is driven by human greenhouse gas emissions. Misleading: While models do play a role in attributing warming to human emissions, this claim ignores the abundance of scientific evidence based on independent observations that also point to the same conclusion. Inaccurate: The Climate Model Intercomparison Project 5 (CMIP5) suite of climate models discussed by May have been shown to reliably reproduce historical trends in climate without evidence of a warming bias.","All available scientific evidence, including independent physical observations, indicates that global warming is driven by human greenhouse gas emissions and that solar forcing plays an extremely minor role in contemporary climate.","""There is no evidence, other than models, that human CO2 emissions drive climate change and abundant evidence that the Sun, coupled with natural climate cycles, drives most, if not all, of recent climate changes""",,"A recent blog post by Andy May published by the CO2 Coalition, a nonprofit organization funded largely by fossil-fuel interest groups, claims that the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC)[1] relies upon model evidence to conclude that greenhouse gas emissions, such as CO2, drive contemporary global warming. May, who presents himself as a retired geologist, goes on to say that these models employ “circular proof” to attribute warming to CO2 emissions and argues that there is “abundant evidence that the Sun, coupled with natural climate cycles, drives most, if not all, of recent climate changes”, rejecting the consensus of scientific evidence that global warming is caused by human greenhouse gas emissions[2-5]. The “abundant evidence” that May invokes is a single article published in a journal unrelated to climate science by Connolly et al. (2021), which uses simple linear regression (itself a basic statistical model) to establish links between solar irradiance and the surface temperature of select northern-hemisphere locations. “It is ironic…that they consider these fairly rigorous and physical model-based methods [of the IPCC] to be disqualifying and yet in the next sentence celebrate Connolly et al’s (2021) ‘simple linear regression’ of surface temperature records against total solar irradiance [which is also a model] as ‘abundant evidence’ that the Sun drives climate change,” commented Henri Drake, a postdoctoral fellow at Princeton University and NOAA’s Geophysical Fluid Dynamics Laboratory. Moreover, observations indicate that solar irradiance has actually decreased since the 1960s, which is in clear contrast to the increasing trend in global surface temperature, showing that the Sun could not have driven warming during this period (Figure 1). Figure 1 – Comparison of the global surface temperature time series (red) and the Sun’s energy that Earth receives (yellow) in watts per square meter since 1880. One can see that since the 1960s, the global temperature and solar activity have varied in opposite directions. Source: NASA/JPL-Caltech. Another reason why scientists know that the Sun is not responsible for modern warming can be found in atmospheric observations. Greenhouse gases absorb heat in the form of infrared radiation in the lower atmosphere (troposphere), resulting in warming of the planet’s surface and lower atmosphere. By contrast, greenhouse gases produce a cooling effect on the upper atmosphere (stratosphere), making the offset between the temperature in the troposphere and stratosphere a useful “fingerprint” of global warming caused by emissions[6-9]. Such a temperature offset between the lower and upper atmosphere is not expected from warming driven by solar irradiance, as this mechanism increases the temperature of the entire atmosphere. Atmospheric observations indicate that the troposphere has warmed while the stratosphere has cooled over the last several decades (Figure 2), in line with expectations of warming driven by greenhouse gases. Figure 2. Global temperature variations in the upper atmosphere (top graph) and in the lower atmosphere (bottom graph) since the 1960s. We observe a warming at the surface and a cooling above, which is consistent with the effect of added greenhouse gases in the atmosphere and inconsistent with the hypothesis of solar influence. Source: Met Office Hadley Centre. In addition to this atmospheric “fingerprint”, incoming and outgoing radiation measurements from satellite observations provide another line of direct evidence linking atmospheric greenhouse gas content to global warming[10,11]. Such studies invalidate May’s statement that “the human influence on climate has never been observed or measured”. When assessing the influence of all possible climate forcing mechanisms in a comprehensive literature review, the Fourth National Climate Assessment of the U.S.[12] identified CO2 and other well-mixed greenhouse gases as the dominant drivers of modern warming whereas the influence of solar activity was shown to be extremely minor (Figure 3), a finding also supported by the IPCC’s Fifth Assessment Report[1] and, more recently, the Sixth Assessment Report[13]. Figure 3. Time evolution in effective radiative forcings (ERFs) across the industrial era for anthropogenic and natural forcing mechanisms. The ERF measures the net heat gain or loss in the Earth’s climate system. Well-mixed greenhouse gases (WMGHG) are the long-lived gases that have a strong impact on climate and include carbon dioxide, methane, nitrous oxide, and different kinds of chlorofluorocarbons. Source: U.S. Fourth National Climate Assessment. May’s claim that climate models use “circular proof” in order to attribute warming to greenhouse gas emissions is rooted in the author’s misunderstanding of a value derived from climate models called transient climate response (TCR). TCR is the degree of model-simulated global warming associated with a 1% increase in CO2 per year compared to the preindustrial CO2 concentration[14]. Referencing Gillett et al., (2013)[14], May writes that previous IPCC models overestimated TCR and that the explicit assumption of the relationship between CO2 and warming in the definition of TCR is an example of “circular proof” when attributing the cause of warming to greenhouse gas emissions. However, TCR is not used in climate models to attribute warming to greenhouse gas emissions, but is rather a metric that scientists calculate to compare the performance of simulations from multiple climate models against each other and observations. Gillett et al. (2013) used more recent model simulations and observational temperature data not available to IPCC authors at the time in order to calculate a new range of estimates for the transient climate response to cumulative carbon emissions (TCRE). Related to TCR, TCRE is defined as “the ratio of global-mean warming to cumulative emissions at CO2 doubling in a 1% [per year] CO2 increase experiment”.[14] The new estimates were found to be between 0.7 and 2.0 K per EgC (exagrams, or 1015 kg, of carbon).[14] By contrast, previous estimates derived from models were reported to be between 0.8 and 2.4 K per EgC. This indicates that the level of simulated global-mean warming caused by greenhouse gas emissions is different for each model. The spread in TCR is due to different representations of the complex physical climate system and biogeochemical processes that models approximate. Thus, they shed light on the importance of accurately representing these processes in models. However, despite inter-model disagreements in TCR, the Climate Model Intercomparison Project 5 (CMIP5) models questioned by May were previously shown to reliably reproduce observational trends in surface land temperature, surface ocean temperature and ocean heat content around the world when using both natural (e.g., the Sun) and anthropogenic (e.g greenhouse gas emissions) forcings since the beginning of the twentieth century, but not natural forcings alone (Figure 4). The range of temperature and ocean heat content values simulated by the suite of CMIP5 models, of which observations generally fall close to the center, does not support May’s statement that models “clearly overestimate” warming. Similar claims about IPCC climate models have been previously reviewed by Climate Feedback and were found to be inaccurate. This is also consistent with more recent research that evaluated the performance of earlier CMIP models and found that “climate models published over the past five decades were skillful in predicting subsequent GMST [global mean surface temperature].”[15] Figure 4. CMIP5 model simulations of land and ocean surface temperatures in addition to ocean heat content since the beginning of the twentieth century using natural and anthropogenic (e.g., greenhouse gas emissions) climate forcings (red) and natural (e.g., solar irradiance) forcings alone (blue). Black lines denote observations. Source: Working Group I, IPCC AR5 Scientists’ Feedback: Henri Drake Postdoctoral research associate, Princeton University: “The author’s conclusion of circular logic is based on their misunderstanding of the TCRE [Transient climate response to cumulative carbon emissions, defined as ‘the ratio of global-mean warming to cumulative emissions at CO2 doubling in a 1% [per year] CO2 increase experiment’[14]]. The definition of the TCRE is not itself ‘proof’ that CO2 emissions drive climate change; it is just a simple metric to summarize Earth’s climate sensitivity to CO2 emissions and to facilitate comparisons between models and observations. The author is correct that detection and attribution methods, as used in the paper, indirectly use models to determine the spatial fingerprints of separate forcing components. It is ironic, however, that they consider these fairly rigorous and physical model-based methods to be disqualifying and yet in the next sentence celebrate Connolly et al’s (2021) ‘simple linear regression’ of surface temperature records against total solar irradiance [which is also a model] as ‘abundant evidence’ that the Sun drives climate change. Worst of all, the author completely ignores the fact that even putting General Circulation Models [the type of state-of-the-art models used by the IPCC] aside completely, there is ‘abundant evidence’ of greenhouse gas-induced climate changes, perhaps most notably the spectrally-resolved measurements of incoming/outgoing radiative fluxes which clearly show the net effects of absorption and re-emission in greenhouse gas bands.[12,13]” References: 1 – IPCC (2013) Working Group I, IPCC AR5. 2 – Oreskes (2004) The scientific consensus on climate change. Science. 3 – Anderegg et al. (2010)Expert credibility in climate change.Proceedings of the National Academy of Sciences. 4 – Cook et al. (2013) Quantifying the consensus on anthropogenic global warming in the scientific literature.Environmental Research Letters. 5 – Cook et al. (2016) Consensus on consensus: a synthesis of consensus estimates on human-caused global warming. Environmental Research Letters. 6 – Lockwood & Fröhlich (2007)Recent oppositely directed trends in solar climate forcings and the global mean surface air temperature. In Proceedings of the Royal Society of London A: Mathematical, Physical and Engineering Sciences. 7 – Lockwood (2008)Recent changes in solar outputs and the global mean surface temperature. III. Analysis of contributions to global mean air surface temperature rise. In Proceedings of the Royal Society of London A: Mathematical, Physical and Engineering Sciences. 8 – Santer et al. (2013)Human and natural influences on the changing thermal structure of the atmosphere.Proceedings of the National Academy of Sciences. 9 – Hegerl & Wallace (2002)Influence of patterns of climate variability on the difference between satellite and surface temperature trends. Journal of Climate. 10 – Raval & Ramanathan (1989). Observational determination of the greenhouse effect. Nature. 11 – Schmidt et al. (2010). Attribution of the present-day total greenhouse effect. Journal of Geophysical Research. 12 – U.S. Fourth National Climate Assessment, Climate Science Special Report. 13 – IPCC (2021). Working Group I, IPCC AR6 14 – Gillett et al. (2013). Constraining the ratio of global warming to cumulative CO2 emissions using CMIP5 simulations. Journal of Climate. 15 – Hausfather et al. (2019). Evaluating the performance of past climate model projects. Geophysical Research Letters."
https://science.feedback.org/review/more-than-75-percent-amazon-rainforest-losing-resilience-the-washington-post-sarah-kaplan/,Mostly accurate,"The Washington Post, Sarah Kaplan, 2022-03-07",More than 75 percent of the rainforest is losing resilience; More than half of the rainforest could be converted into savanna in a matter of decades,,"Accurate: A recent study found that “more than three-quarters of the Amazon rainforest has been losing resilience since the early 2000s.""  Imprecise: Rather than turn into a savanna ecosystem, the Amazon rainforest would more likely transition into a “savanna-like” ecosystem. The difference would be that the degraded Amazon ecosystem would not contain as many tree species and would not store as much carbon as a savanna ecosystem.","The Amazon rainforest is the largest rainforest in the world, home to a vast array of biodiversity, including many species yet to be discovered by scientists. It faces significant risks from deforestation and climate change, and recent research shows that these threats are causing much of the forest to lose resilience – the ability to bounce back from disturbances such as logging, fire and drought.",Satellite images taken over the past several decades reveal that more than 75 percent of the rainforest is losing resilience...This widespread weakness offers an early warning sign that the Amazon is nearing its “tipping point”; The ecosystem could suffer sudden and irreversible dieback. More than half of the rainforest could be converted into savanna in a matter of decades,,"On March 7, the Washington Post published a story about the declining health of the Amazon. The story, based on a March study published in Nature Climate Change, reported that, according to satellite images, the Amazon rainforest is “nearing its tipping point,” with more than 75 percent of the rainforest losing resilience.[1] The Nature Climate Change study analyzed the Amazon’s resilience since the early 2000s and, consistent with the claim in the Washington Post, it found that “more than three-quarters of the Amazon rainforest has been losing resilience since the early 2000s.” The Washington Post’s claim “is 100% correct and it is the main result of the article on Nature Climate Change,” said Carlos Nobre, earth system scientist at the University of São Paulo, Brazil’s Institute of Advanced Studies. Research shows that the Amazon rainforest – the largest rainforest in the world – faces “dual threats” of climate change and deforestation.[2] A 2021 study estimated that, as a result of human activities, the Amazon has seen a “forest loss of around 17%, of which 14% has been converted mostly to agricultural land.”[3] Deforestation and climate change can lead to reduced dry season rainfall in the Amazon, and this lack of rain can lead to reduced forest resilience, making it more susceptible to future stressors, such as fire, drought and logging.[4] The image shows the decline of moisture in the air over the Amazon rainforest, particularly across the south and southeastern Amazon, during the dry season months – August through October – from 1987 to 2016. The measurements are shown in millibars. Credit: NASA/JPL-Caltech, NASA Earth Observatory “The twin pressures of deforestation and climate change on the Amazon rainforest remain a great concern,” Peter Cox, professor of climate system dynamics at the University of Exeter, wrote in Carbon Brief in 2020. “We are unlikely to know the vulnerability of the rainforest to climate change with any confidence until it is too late. However, we are sure that human-caused deforestation reduces the resilience of the forest to climate change and other stressors.” As reported by Carbon Brief, the Nature Climate Change study’s lead author Chris Boulton noted in a press conference that, although his study shows that the Amazon rainforest is “approaching a tipping point” – the point when changes in the forest become irreversible – it is unclear, based on research so far, when that tipping point will occur. The Washington Post also claims that “more than half of the rainforest could be converted into savanna in a matter of decades.” That claim “needs a few considerations,” Nobre said. “The conversion to tropical savanna natural ecosystem is more complicated and it would take many centuries,” Nobre said. “The likely conversion is towards open canopy degraded ecosystems. They may look like a tropical savanna, but not with all the tree species and also not storing as much carbon in the soil.” Scientists’ Feedback: Carlos Nobre Earth System Scientist, University of São Paulo, Brazil’s Institute of Advanced Studies: The first [claim – “satellite images taken over the past several decades reveal that more than 75 percent of the rainforest is losing resilience”] is 100% correct and it is the main result of the article on Nature Climate Change. The second [claim] needs a few considerations. Particularly, the sentence “more than half of the rainforest could be converted into savanna in a matter of decades”. The conversion to tropical savanna natural ecosystem is more complicated and it would take many centuries. The tropical savannas to the south and north of the Amazon rainforest are very rich in fire-resistant tree species. The likely conversion is towards open canopy degraded ecosystems. They may look like a tropical savanna, but not with all the tree species and also not storing as much carbon in the soil. Perhaps the sentence could be: “more than half of the rainforest could be converted into ‘savanna’-like open canopy degraded ecosystems in a matter of decades”. References: Boulton et. al (2022). Pronounced loss of Amazon rainforest resilience since the early 2000s. Nature Climate Change. Malhi et. al (2008). Climate Change, Deforestation, and the Fate of the Amazon. Science. Gatti et. al (2021). Amazonia as a carbon source linked to deforestation and climate change. Nature Climate Change. Zemp et. al (2017). Deforestation effects on Amazon forest resilience. Geophysical Research Letters."
https://science.feedback.org/review/wall-street-journal-steven-koonin-publishes-misleading-claims-climate-change-influences-greenland-ice-melt/,-1.75,"The Wall Street Journal, by Steve Koonin, on 2022-02-17.",,"""Greenland’s Melting Ice Is No Cause for Climate-Change Panic""",,,,[1] Briner et al. (2020). Rate of mass loss from the Greenland Ice Sheet will exceed Holocene values this century. Nature. [2] Trusel et al (2018) Nonlinear rise in Greenland runoff in response to post-industrial Arctic warming. Nature. [3] 1 – Kjeldsen et al. (2015) Spatial and temporal distribution of mass loss from the Greenland Ice Sheet since AD 1900. Nature. [4] The IMBIE Team (2019). Mass balance of the Greenland Ice Sheet from 1992 to 2018. Nature. [5] Kjeldsen et al. (2015). Spatial and temporal distribution of mass loss from the Greenland Ice Sheet since AD 1900. Nature. [6] Hugonnet et al (2021). Accelerated global glacier mass loss in the early twenty-first century. Nature. [7] Church et al. (2013). Sea Level Change. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. [8] Aschwanden et al. (2019). Contribution of the Greenland Ice Sheet to sea level over the next millennium. Science advances. [9] Nerem et al. (2018) Climate-change–driven accelerated sea-level rise detected in the altimeter era. Proceedings of the National Academy of Sciences.,"Reviewers’ Overall Feedback: Lauren Simkins Assistant Professor, University of Virginia: While the article uses real data on ice mass balance of the Greenland Ice Sheet, the message of slower rate of ice mass loss in the past 8-9 years does not mean that human-induced warming is not a concern, or less of a concern now. The slower rates of ice mass loss highlight the dynamic, non-linear, and often asynchronous response of the ice sheet to short (annual and sub-annual) changes in weather; yet the long-term, multi-decadal trends in climate and ice mass loss are where we should focus our attention. Overall, the article is, I believe, intentionally misleading and flawed, by presenting real data to support inaccurate interpretations and potential outcomes. Marco Tedesco Lamont Research Professor, Lamont-Doherty Earth Observatory of Columbia University: The article picks only the last 10 years, excluding the remaining time series for the context, hence “cherry-picking” that period and not considering many climatic factors when describing the downward trend. Eric Rignot Professor, University of California Irvine & Jet Propulsion Laboratory: The article does not quote clear sources and time periods for mass loss, which is increasing with time. Quoted numbers, 110gt/yr, is low and obscure. The article does not discuss the linkage between physical processes driving the mass loss and human activities, hence has little logic and physical basis for making claims. The article’s claims exaggerate the statements made by scientists about the urgency of the situation but the argument is vague, not quantitative and hand wavy. The old argument that the 30s were warmer than present is false. Anders Anker Bjork Assistant professor, University of Copenhagen: Science knows what caused the early 20th century warming and what is causing the current warming. The WSJ title could just as well have been: ‘Last decade showed highest mass loss from Greenland ever measured’. Annotations: “The average annual ice loss … would cause sea level to rise by 3 inches by the end of this century, Jason Briner Professor, Department of Geology, University at Buffalo: Of course keep this 3” in perspective. This does not include sea level coming from Antartica, from mountain glaciers, from thermal expansion of the oceans. It is a little narrow (and sure, maybe underwhelming for some) to consider just one of these sources in isolation. “and if losses were to continue at that rate, it would take about 10,000 years for all the ice to disappear, causing sea level to rise more than 20 feet” Jason Briner Professor, Department of Geology, University at Buffalo: This is only true if the rate of annual ice loss were to remain the same as today’s rate for a long time. That said, highly vetted and peer-reviewed climate and ice sheet models, which are very good at correctly modeling Earth’s past, suggest that the present rates of ice sheet mass loss will not stay the same, but will increase.[1] Lauren Simkins Assistant Professor, University of Virginia: Rather than extrapolating cumulative ice loss, a peer-reviewed study that uses fine-scale ice sheet model with uncertainty quantification indicates the Greenland Ice Sheet could disappear entirely in 1,000 years.[8] The “notion that humans are melting Greenland” is “simplistic”, “There are large swings in the annual ice loss and it is no larger today than it was in the 1930s, when human influences were much smaller”, “the annual loss of ice has been decreasing in the past decade even as the globe continues to warm.” Jason Briner Professor, Department of Geology, University at Buffalo: Of course such a statement is simplistic, yet still likely more or less true. And of course there are large swings in the annual ice loss rate – these swings have tracked well both Arctic climate (on decadal scales) and with modes of climate variability and weather patterns (on the sub-decadal scale). Annual loss has been decreasing in the past decade Lauren Simkins Assistant Professor, University of Virginia: The rate of ice mass loss has decreased since 2013, yet the annual loss of ice is still considerable and reflects the long-term impact of atmospheric warming and ice dynamic response to such.[4] [The WSJ article also criticizes the following statement made by, according to Koonin, “the media and politicians”:] “Greenland ice sheet on course to lose ice at fastest rate in 12,000 years.” Jason Briner Professor, Department of Geology, University at Buffalo: Of course this hits home, as the author of the paper with more or less that title. There’s nothing about this statement that is incorrect or exaggerated. It is important to know that it is based on a study that compiled and modeled rates of mass loss PER CENTURY and relies on the well-vetted models mentioned above to provide best estimates (with ranges given uncertainties) for this century (which isn’t over yet!). Our model, which performed well in simulating Greenland’s history, and stacks up well against other models that took part in a state-of-the-art model comparison effort, suggests that rates this century will, on average, have higher mass loss rates than at present as the Arctic is expected to heat up. It is all this information that goes into that quote. Its shrinking has been a major cause of recent sea-level rise, but as is often the case in climate science, the data tell quite a different story from the media coverage and the political laments Lauren Simkins Assistant Professor, University of Virginia: The data reflect major losses of ice, via ice thinning, ice mass loss, and accelerated ice discharge, despite a lower magnitude of overall ice mass loss since 2013; but the mass balance is still negative and on track (based on the multi-decadal trend) to continue to lose mass. Since human warming influences on the climate have grown steadily—they are now 10 times what they were in 1900— you might expect Greenland to lose more ice each year. Instead there are large swings in the annual ice loss and it is no larger today than it was in the 1930s, when human influences were much smaller. Lauren Simkins Assistant Professor, University of Virginia: This is a really simplistic interpretation that negates physics of glacial ice and its response to annual ocean and atmospheric temperatures. The non-linear response of the Greenland Ice Sheet to warming and the lag time between, for example, a warm month or couple of months and ice mass loss means that there are asynchronous changes in climate and ice mass balance."
https://science.feedback.org/review/prageru-video-on-climate-change-repeats-a-range-of-misleading-claims-by-steven-koonin/,-1.4,"PragerU, by Steve Koonin, on 2024-10-25.",,"""Is There Really a Climate Emergency?""",,,,,"Reviewers’ Overall Feedback: Mark Richardson Research Associate, Colorado State University/NASA JPL: The author of this video, Dr. Steven Koonin, says he is following the scientific reports published by the UN and US government, but by subtly changing wording and choosing not to mention important context this video is very likely to mislead readers. This style of selective wording and lack of context, an approach called “cherry picking”, applies to every one of Dr. Koonin’s scientific comments. Justin Schoof Professor and Chair, Southern Illinois University: Many statements are misleading and others are simply incorrect. Mark Zelinka Research Scientist, Lawrence Livermore National Laboratory: I believe most of Dr. Koonin’s talking points have been refuted in several other places, most notably here on climatefeedback.org. It appears as though most of the PragerU talking points are the same as those in his book and have not been updated to reflect being repeatedly corrected by the climate science community. Andrew King Research fellow, University of Melbourne: This video has many major errors and it is difficult to review the veracity of many claims due to the lack of referencing of sources. Ilissa Ocko Climate Scientist, Environmental Defense Fund: This piece is very misleading and uses borderline inaccurate/cherry-picked “facts” and flawed reasoning to make its case. For example, there is myriad evidence that many extreme weather events are intensifying and/or becoming more frequent in most parts of the world (see Intergovernmental Panel on Climate Change Sixth Assessment Report Working Group I Chapter 11, 2021); the extent depends on the region and the type of event, and therefore sweeping generalities (e.g. global flooding) or cherry-picked examples (e.g. heat waves in the U.S) do not adequately convey the severity of climate change in impacting communities and ecosystems worldwide.Annotations: The statements quoted below are from the video; comments are from the reviewers (and are lightly edited for clarity). Claim: “For example, government reports state clearly that heat waves in the US are now no more common than they were in 1900.” Justin Schoof Professor and Chair, Southern Illinois University: Many statements are misleading and others are simply incorrect. As a single example, there is a statement regarding heat waves in the U.S. being no worse than they were in 1900, according to government reports. Figure 1.2 of the 2018 U.S. National Climate Assessment clearly shows an increase in heat waves in recent decades. Heat waves are getting worse in the United States, especially in recent decades. Parts of the early 20th century, particularly the 1930s, were very warm in the United States. This was regional rather than global, but can be used to make recent changes in the US seem less relevant than they are. Lastly, we expect warming from greenhouse gases to impact minimum temperatures more than maximum temperatures and that’s exactly what’s happening. It makes for less dramatic warming in the maximums relative to the minimums. Daniel Swain Climate Scientist, University of California, Los Angeles: There is now extensive evidence that heatwaves are increasing due to global warming, both globally and also specifically in the United States–and recent government reports (in addition to peer-reviewed research in other venues) reflect this. For example: The EPA and the National Climate Assessment. It is true that heatwaves in the United States, although they are indeed increasing in aggregate, have increased at a slower rate than across much of the rest of the globe. But the reality is that the United States is indeed experiencing more extreme heat today than it was decades ago. Claim: “Hurricane activity is no different than it was a century ago.” Kevin Walsh Professor of Meteorology, University of Melbourne: The most recent authoritative assessment of this particular issue (Knutson et 2019), of which I was a co-author, concluded the following (among other conclusions): 1. There has been a poleward migration of tropical cyclone tracks in the western North Pacific region. 2. There has been an increase in the global proportion of very intense tropical cyclones in recent decades, as well as an overall increase in tropical cyclone intensity. 3. There has been an increased incidence of intense precipitation events associated with tropical cyclones in the Gulf of Mexico region. It was also concluded that these changes were likely due to anthropogenic climate change. So I’m not sure how this leads the author to state that there has been no change in hurricane activity in the last 100 years. Kerry Emanuel Professor of Atmospheric Science, MIT: [Comment from a previous evaluation of a similar claim.] This statement is flat out wrong. In the first place, the theoretically predicted trends would not have been detectable in the sparse and noisy hurricane record until recently, and in fact they HAVE recently been detected. The most up-to-date research published in the Proceedings of the National Academy of Sciences demonstrates an increase in the proportion of hurricanes that become major hurricanes (Category 3-5) globally, supporting theoretical predictions that date back to 1987 (see figure below). The proportion of major hurricane intensities to all hurricane intensities globally from 1979-2017. Data is binned into 3-year periods. The proportion of global major hurricanes increased by 25% over the 39-year time period analyzed. From Kossin et al. (2020).[20] Claim: “Floods have not increased across the globe over more than seventy years.” Mark Richardson Research Associate, Colorado State University/NASA JPL: Regarding floods, there are several types including flash, coastal and river flooding. The UN report [2] states that heavy rain events have gotten more extreme and more common “over a majority of land regions with good observational coverage since 1950”, and although some regions dried, the general tendency is therefore higher flash-flood risk (our recent work supports this[7]). Meanwhile, at tide gauges scattered around Earth’s coasts there has been a “median 165% increase in high-tide flooding over 1995—2014 relative to 1960—1980”. Changes in high river levels depend on the region, but the data are sparse so there is “low confidence” in global changes. Dr. Koonin chooses not to report the increased flash or coastal flooding risk, but instead states that global floods haven’t increased. This is not supported by the report he claims to be using. Claim: “Greenland’s ice sheet isn’t shrinking any more rapidly today than it was 80 years ago.” Daniel Swain Climate Scientist, University of California, Los Angeles: The Greenland Ice Sheet is currently melting at a rate comparable to (or greater than) any in the past 12,000 years, let alone 80 years ago. For more on this claim, see our article review from April 2021. Claim: “The media, the politicians, and a good portion of the climate science community attribute every terrible storm, every flood, every major fire to “climate change.” Daniel Swain Climate Scientist, University of California, Los Angeles: This statement is not a quantitative claim, but it appears to connote that scientists are systematically attributing extreme events to climate change without evidence. This is simply not correct. In fact, an entire sub-field of climate and atmospheric science has developed in recent years specifically aimed at developing and implementing scientifically valid methods of attributing specific extreme events to climate change (known as “extreme event attribution.”) It’s impossible to make a blanket statement about all kinds of extreme events (global warming is increasing the frequency and intensity of global heatwaves, for example, but decreasing the intensity of global cold snaps), but numerous scientists around the world now conduct research on this specific topic, and often find physically and statistically overwhelming evidence that climate change has increased the risk of specific events such as individual extreme heatwaves and extreme downpours (among other types of events). Some overviews of how “extreme event attribution” is conducted, as well as examples of applications to specific events, include: https://www.cell.com/one-earth/fulltext/S2590-3322(20)30247-5https://www.nap.edu/read/21852/chapter/5https://www.nature.com/articles/nclimate2657 Andrew King Research fellow, University of Melbourne: This video has many major errors and it is difficult to review the veracity of many claims due to the lack of referencing of sources. Here, I’ll just focus on the claim that scientists, the media and politicians attribute every extreme event to climate change. A community of climate scientists has worked to develop a robust and comprehensive methodology for thorough analysis of how human-caused climate change affects extreme weather events.[10,11] This approach has indeed been used to demonstrate that there are often very large effects of human-caused climate change on some events, such as the Siberian heat event of 2020.[16] It is incorrect to say that scientists link climate change to every single extreme event as some studies have not identified a clear link to some extreme events (a comprehensive set of the findings of these studies can be found here). It is the case that climate change is worsening many extreme weather events, particularly heatwaves, but this conclusion is founded on a large and growing number of peer-reviewed studies. Claim: “Natural fluctuations in the height and coverage of clouds have at least as much of an impact on the flows of sunlight and heat as do human influences. But how can we possibly know global cloud coverage say 10, let alone 50 years from now? Obviously, we can’t. But to create a climate model, we have to make assumptions. That’s a pretty shaky foundation on which to transform the world’s economy.” Timothy Myers Postdoctoral Researcher, Lawrence Livermore National Laboratory: These statements are very misleading and not logically coherent. While it is true that natural fluctuations in clouds can have impacts on the fluxes of heat and solar radiation as large or larger than those associated with climate change, this is neither a profound statement nor does it provide insight into how clouds will respond to planetary warming. To take another example, the natural fluctuations of Earth’s temperature in a given hemisphere from winter to summer are larger than the temperature rises due to human influences. But this tells us absolutely nothing about what the human influence on Earth’s temperature actually is. Moreover, there is indeed large climate model uncertainty with respect to how certain cloud types will respond to climate change[8]. But observations, theory, and high-resolution cloud models collectively provide evidence for how a variety of cloud types will change as unabated global warming continues[12-15]). In general, multiple lines of independent evidence inform our understanding of the human influence on climate – we do not rely on climate models alone[12]. This variety of evidence overwhelmingly suggests that the world’s economy must phase out the use of fossil fuels to ensure that the planet remains hospitable to organized human life. Mark Zelinka Research Scientist, Lawrence Livermore National Laboratory: Koonin is correct that subtle variations in cloud height, amount, and reflectivity can strongly modify Earth’s ability to absorb sunlight and emit heat to space. He is also correct that the need to model the entire planet’s climate for centuries precludes simulating the very small-scale processes that are involved in cloud formation, and this means that assumptions must be made around clouds in models. The upshot of this is that climate models disagree on how clouds will respond to warming[9]. This is why a grand challenge in climate research is to determine the extent to which clouds can act as a feedback on global warming [21]. If, say, low-level highly reflective clouds increase in coverage as the planet warms, this will decrease the amount of sunlight absorbed by the planet and put the brakes on warming. But if these clouds decrease in coverage with warming, this will allow more sunlight to be absorbed, thereby exacerbating warming relative to what it would be if clouds didn’t change – a positive feedback. There are, however, several key points left out of Koonin’s cloud argument. Koonin’s statements may lead you to believe that predictions of future warming are built on a house of cards, with everything resting on poorly-simulated clouds. The truth is that cloud changes can only modulate warming, not stop or reverse it[8]. There is no conceivable scenario in which cloud feedback prevents warming in the face of rising human emissions of greenhouse gases. In a world with rising CO2 emissions, how clouds respond determines whether the future is hotter or much hotter; steady or colder temperatures are simply off the table. Moreover, a plethora of evidence from detailed analyses of satellite cloud observations as well as very high resolution modeling (which do not require assumptions about key cloud processes) indicates that cloud changes provide an amplifying feedback[13][14[15][22][23]. This means that climate models, on average, predict the right sensitivity of climate to CO2 – around 3 C (5.4 F) for a doubling of CO2[12]. Moreover, satellite-based cloud records are now long enough that we can see trends that confirm many of the cloud responses that climate models predict to occur with warming [24][25]. Finally, climate scientists do not blindly follow climate model projections. We are well-aware that uncertainties surrounding clouds affects our ability to know precisely what future warming holds, and focus on predictions from models that better match observations. This means down-weighting models that are very insensitive to CO2 as well as those that are too sensitive to CO2. The latest IPCC report[2] in particular does this for most if not all projections. Summary: To correctly note that clouds lead to uncertainties in future climate prediction without simultaneously clarifying (1) that “no big deal” is not in the range of plausible futures (unless emissions are reduced), and (2) that a huge body of evidence now points to clouds providing an amplifying feedback on warming, is very misleading. To position oneself as a rogue truth-teller, bringing to light uncertainties that climate scientists are trying to bury or ignore despite abundant evidence to the contrary is, well, hubris. Claim: “Projecting future climate is excruciatingly difficult. Yes, there are human influences, but the climate is complex. Anyone who says that climate models are “just physics” either doesn’t understand them or is being deliberately misleading.” Mat Collins Professor, University of Exeter: This is a bit of a tricky one, I think. Much of what he says is at least partially true and the same points have been used to argue that we must urgently do something about climate change. It is really just the general dismissive tone and language of the piece. Deconstructing [this claim], for example, Yes making climate projections is complex He admits human influence Yes climate models do make approximations to the laws of physics For a general rebuttal, I think I would invoke the precautionary principle. Yes we don’t know everything we would like to about the complex details of climate change but we know enough that we should do something about it. Claim: “It takes centuries for the excess carbon dioxide to vanish from the atmosphere. So, any partial reductions in CO2 emissions would only slow the increase in human influences—not prevent it, let alone reverse it.” Ilissa Ocko Climate Scientist, Environmental Defense Fund: An example of flawed reasoning is that while the author is correct that CO2 can last for a long time in the atmosphere, and therefore partial reductions would only slow the increase in warming (and not prevent or reverse it), this does not mean that reductions in CO2 are not beneficial compared to what would happen otherwise. In fact, it is the opposite; every ton of CO2 we emit can commit us to warming for generations to come, meaning that every ton we reduce can help us avoid warming for centuries as well. Further, emissions goals are not just to reduce CO2 emissions, but to achieve “net zero” emissions by midcentury (a state in which we are not adding CO2 to the atmosphere beyond what can be removed) and then ultimately achieving negative CO2 emissions (more CO2 removed from the atmosphere than added); these actions *would* prevent additional warming and could even reverse warming.References: [1] Reidmiller et al. (2018) Chapter 1: Overview. In Impacts, Risks, and Adaptation in the United States, Fourth National Climate Assessment, Volume II. [2] IPCC (2021) Climate Change 2021: The Physical Science Basis. Contributions of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. [3] Knutson et al. (2019) Tropical cyclones and climate change assessment: Part I, Detection and attribution. Bulletin of the American Meteorological Society. [4] Knutson et al. (2021) Climate change is probably increasing the intensity of tropical cyclones. Science Brief. [5] Swain et al. (2020) Increased Flood Exposure Due to Climate Change and Population Growth in the United States. American Geophysical Union. [6] Sweet et al. (2018) Patterns and Projections of High Tide Flooding Along the U.S. Coastline Using a Common Impact Threshold. NOAA Technical Report NOS CO-OPS 086. [7] Chinita et al. (2021) Global mean frequency increases of daily and sub-daily heavy precipitation in ERA5. Environmental Research Letters. [8] Zelinka et al. (2017) Clearing clouds of uncertainty. Nature Climate Change. [9] Zelinka et al. (2020) Causes of Higher Climate Sensitivity in CMIP6 Models. Geophysical Research Letters. [10] Van Oldenborgh et al. (2021) Pathways and pitfalls in extreme event attribution. Climatic Change. [11] Philip et al. (2020) A protocol for probabilistic extreme event attribution analyses. Advances in Statistical Climatology, Meteorology and Oceanography. [12] Sherwood et al. (2020) An Assessment of Earth’s Climate Sensitivity Using Multiple Lines of Evidence. Reviews of Geophysics. [13] Myers et al. (2021) Observational constraints on low cloud feedback reduce uncertainty of climate sensitivity. Nature Climate Change. [14] Ceppi et al. (2021) Observational evidence that cloud feedback amplifies global warming. Proceedings of the National Academy of Sciences. [15] Cesana et al. (2021) Observational constraint on cloud feedbacks suggests moderate climate sensitivity. Nature Climate Change. [16] Ciavarella et al. (2021) Prolonged Siberian heat of 2020 almost impossible without human influence. Climatic Change. [17] Swain et al. (2020) Attributing Extreme Events to Climate Change: A New Frontier in a Warming World. One Earth. [18] Trenberth et al. (2015) Attribution of climate extreme events. Nature Climate Change. [19] Kjeldsen et al. (2015) Spatial and temporal distribution of mass loss from the Greenland Ice Sheet since AD 1900. Nature. [20] Kossin et al. (2020) Global Increase in Major Tropical Cyclone Exceedance Probability over the Past Four Decades. Proceedings of the National Academy of Sciences. [21] Bony et al. (2015) Clouds, circulation and climate sensitivity. Nature Geoscience. [22] Klein et al. (2017) Low-Cloud Feedbacks from Cloud-Controlling Factors: A Review. Surveys in Geophysics. [23] Bretherton (2015) Insights into low-latitude cloud feedbacks from high-resolution models. Philosophical Transactions of the Royal Society A. [24] Marvel et al. (2015) External Influences on Modeled and Observed Cloud Trends. Journal of Climate. [25] Norris et al. (2016) Evidence for climate change in the satellite cloud record. Nature."
https://science.feedback.org/review/coral-cover-great-barrier-reef-improved-2021-but-doesnt-mean-reef-growing-quickly-contrary-to-daily-wire/,Misleading,"The Daily Wire, Ben Zeisloft, 2021-10-24",Study Shows The Great Barrier Reef Is Growing Quickly,,"Lack of context: Research shows that the Great Barrier Reef faces ongoing threats from climate change, including warmer ocean temperatures and more intense tropical cyclones. These threats pose long-term danger to coral reefs and can easily reverse short-term growth in coral cover.  Misleading: The claim fails to note that the growth in coral cover is driven by Acropora, a genus of coral that’s particularly susceptible to stressors including coral bleaching, wave damage, and predators.  Overstates the scientific impact of a finding: After being hit by multiple, widespread stressors between 2014 and 2020, 2021 was a relatively stressor-free year for the Great Barrier Reef, giving coral cover a chance to recover, according to an Australian Institute of Marine Science report. However, short-term recoveries in coral growth can be reversed quickly, and are not proof that the Great Barrier Reef as a whole is growing.","As the planet’s largest coral reef ecosystem, the Great Barrier Reef is home to thousands of marine species and is a major contributor to the Australian economy. However, its size and status cannot protect it from the impacts of climate change. The reef remains vulnerable to ocean warming, more intense storms, predator outbreaks, and other stressors caused by climate change. Warmer ocean temperatures can cause coral to “bleach”,  a process in which they dispel symbiotic algae living within their tissue, which leaves them weaker and more susceptible to death. Under the right conditions, bleached coral can recover, but a single, low-disturbance year does not provide scientists enough data to make judgements on overall reef health, as short-term recovery can quickly be reversed.","Despite Climate Change Fearmongering, Study Shows The Great Barrier Reef Is Growing Quickly [...] The Australian government’s most recent official report on reef recovery indicates that coral cover at the Northern Great Barrier Reef “continued to increase to 27% from the most recent low point in 2017.” Meanwhile, the Central Great Barrier Reef saw a 26% increase in hard coral cover.",,"The Daily Wire published an article on 24 October, 2021 which claimed that a report from the Australian government found the Great Barrier Reef is “growing quickly”. The report the article references is the Australian Institute of Marine Science (AIMS) Long-Term Monitoring Program Annual Summary: Report of Coral Reef Condition 2020/2021[1], which summarizes the current health of the three regions of the Great Barrier Reef (Northern, Central, and Southern) based on scientific surveys conducted between August 2020 and April 2021. The Daily Wire’s claims misrepresent the findings of the AIMS report. The report stated that, after being hit by multiple, widespread stressors between 2014 and 2020, including “numerous severe tropical cyclones and three mass coral bleaching events in five years”, 2021 was a “low disturbance” year for the Great Barrier Reef. This lull in stressors allowed corals on the reef to begin recovering, and coral cover increased across all three Great Barrier Reef regions between 2020 and 2021. However, this increase in coral cover does not mean the reef is “growing quickly”, as claimed in the article. A single year is far too short a timeline to judge overall reef growth, explained Professor Terry Hughes, former director of the ARC Centre of Excellence for Coral Reef Studies. “The reefs are not growing or shrinking – that’s a geological process that occurs over centuries or more,” he said. “Growth rates of individual corals is not a conventional way to assess the condition of reefs.” A key point of context that was missing from the Daily Wire article is that the increase in coral cover described in the AIMS report is being driven by Acropora coral. This fast-growing genus tends to be more susceptible to wave damage, coral bleaching, and predation by the crown-of-thorns starfish. That means that, when faced with these stressors, any increase in Acropora coral cover that was previously documented can quickly be reversed. “The corals that grow back rapidly – Acropora ‘branching’ corals – are also very sensitive to human impacts, so this recovery will be temporary if climate change continues,” Chris Brown, a senior lecturer in the School of Environment and Science at Griffith University in Queensland, Australia, said. “A shift in the types of corals will have implications for the animals that use them as habitat, including the Great Barrier Reef’s valuable fisheries”. The AIMS report stated that the Great Barrier Reef continues “to be exposed to cumulative stressors, and the prognosis for the future disturbance regime is one of increased and longer lasting marine heatwaves and a greater proportion of severe tropical cyclones”. It also notes that the recovery outlined in the report “has been seen previously and can be reversed in a short amount of time”. This is important context that the Daily Wire article leaves out. Brown said in an email that some coral recovery was expected on the Great Barrier Reef after high-disturbance events. Brown referenced an “unprecedented” coral bleaching event in the Great Barrier Reef in 2016, which occurred as the result of record-high sea surface temperatures[2] and caused widespread bleaching and coral death. The bleaching event was the third global-scale coral bleaching event since the 1980s[3]. “Some types of coral will grow back rapidly after diebacks if they are left undisturbed,” Brown said in an email. “Unfortunately, the future prospects look dire, we expect heatwaves like that to occur 1 in every 3 years in the future due to climate change and greenhouse gas emissions.” Predictions like that are important for the long-term health of reefs, because frequent marine heat waves (along with other frequent disturbances) make it difficult for corals to make long-term recoveries, especially longer-lived species. As Hughes et al. noted in a 2017 study[3]: “The recovery time for coral species that are good colonizers and fast growers is 10–15 years, but when long-lived corals die from bleaching their replacement will necessarily take many decades. Recovery for long-lived species requires the sustained absence of another severe bleaching event (or other significant disturbance), which is no longer realistic while global temperatures continue to rise. Therefore, the assemblage structure of corals is now likely to be permanently shifted at severely bleached locations in the northern Great Barrier Reef.” Figure 1—The AIMS report visualized why August 2020 – April 2021 was a relatively good year for coral health in the Great Barrier Reef: low rates of bleaching and crown of thorns starfish (COTS) led to increases in coral cover across many of the reefs. The figure shows: a) The percentage of hard coral cover along the different segments of the reef. b) How different regions of the reef have changed in coral cover between 2021 and the previous survey (i.e. levels of increase or decrease in coral cover). c) The presence and severity of the COTS outbreak throughout the reef’s regions. d) The percentage of coral colonies affected by bleaching during the survey dates.Contrary to the Daily Wire’s claim, researchers found that coral growth rate on the Great Barrier Reef has declined in recent decades. In a 2012 study[4], for instance, De’ath et al. state that “coral cover depends not only on mortality from acute disturbances but on rates of growth. Rates of coral calcification on the GBR [Great Barrier Reef] and many other reef systems around the world have declined by 15–20% since ∼1990 due to increasing thermal stress”. Hughes et al. (2019)[5] also found that, in the Northern and Central Great Barrier Reef, corals’ rate of recruitment, which is the rate at which coral larvae attach themselves to a substrate and grow into adult coral, “has been substantially diminished” due to climate change and other stressors. Because of this diminished recruitment rate, the reef’s resilience to bleaching is “compromised”, the study stated. Lastly, a 2020 study by Dietzel et al.[6] documented “the systematic decline of absolute coral abundances across size classes, habitats, sectors and taxa on the GBR over the last two decades.” Along with thermal stress, more intense tropical cyclones are predicted to continue to threaten the Great Barrier Reef as climate change progresses: as Cheal et al. (2017)[7] note: “increases in cyclone intensity predicted for this century are sufficient to greatly accelerate coral reef degradation.” In addition to its misleading claim about reef growth, the Daily Wire article also makes a numerical error in its claim that “the Central Great Barrier Reef saw a 26% increase in hard coral cover”. The report stated that coral cover in the Central Great Barrier Reef “increased to 26% in 2021” while coral cover was at around 14% in years past—not that it increased by 26%. Since 2009, the Great Barrier Reef has faced three bleaching events, a wave of crown-of-thorn starfish outbreaks, and 17 cyclones. The coral growth seen during 2021 is encouraging, but as climate change continues, the reef risks having fewer and fewer low-disturbance years like this one to recover.UPDATE (2 Nov. 2021): The Daily Wire has issued a correction to its article, updating the headline to make clear the distinction between coral cover and reef size, and adding more context about Acropora coral. It also corrected the claim that coral cover in the Central Great Barrier Reef grew by 26% during the study period.Scientists’ Feedback: Chris Brown Research Fellow, Griffith University: Some types of coral will grow back rapidly after diebacks if they are left undisturbed. There was an unprecedented heatwave in 2016 that caused coral bleaching and death, so some regrowth since then is expected. Unfortunately, the future prospects look dire, we expect heatwaves like that to occur 1 in every 3 years in the future due to climate change and greenhouse gas emissions. Australia has some of the highest per-capita emissions of any nation globally, and fossil fuel extraction that contributes significantly to greenhouse gas emissions here and overseas. So it’s crucial for corals and all of Earth’s ecosystems that Australia urgently commit to substantial and rapid action to reduce fossil fuel extraction and emissions. With the COP upcoming in Glasgow now is the time to do that. Independent surveys of the Great Barrier Reef conducted by the Reef Life Survey confirm that the health of the reef’s corals is currently poor (you can view trends for habitat cover, ie corals, here). Recent and ongoing heatwaves are a major contributor to that, as are impacts from pollution and crown of thorns starfish predation. The report from AIMS also notes the types of corals growing on the reefs are changing. The corals that grow back rapidly – Acropora ‘branching’ corals, are also very sensitive to human impacts, so this recovery will be temporary if climate change continues. A shift in the types of corals will have implications for the animals that use them as habitat, including the Great Barrier Reef’s valuable fisheries. In 2016 we observed changes in the fish community in response to loss of corals and directly to the heatwave. The Reef Life Survey are conducting ongoing monitoring of the fish, which will help inform us about the impacts of these changes on valuable fisheries.Terry Hughes Professor, ARC Centre of Excellence for Coral Reef Studies, James Cook University: The report points out that where coral cover has increased (after bleaching in 2016 and 2017), the new corals are weedy species that are the most susceptible to the inevitable next heatwave. According to the report, one in six reefs surveyed in early 2021 has shown no increase in coral cover. None of the 20 reefs survey by AIMS in the southern region were affected by coral bleaching in 2016, 2017 or 2020. Many of these climate change denying blogs seem to confuse ups and downs in % coral cover with “reef growth” or “coral growth”. The reefs are not growing or shrinking – that’s a geological process that occurs over centuries or more. Growth rates of individual corals is not a conventional way to assess the condition of reefs. Another source of confusion in these blogs is relative versus absolute changes in coral cover. For example, an increase from 10 to 12% is often misrepresented as a 20% improvement, instead of a 2% gain (and an absolute change, up or down, of 2% is well within the measurement error).REFERENCES: [1] Annual Summary Report of Coral Reef Condition 2020/2021. (2021) Australian Institute for Marine Science. [2] Australia State of the Environment Report: Marine environment: 2011–16 in context. (2016) Commonwealth of Australia. [3] Hughes et al. (2017) Global warming and recurrent mass bleaching of corals. Nature. [4] De’ath et al. (2012) The 27–year decline of coral cover on the Great Barrier Reef and its causes. Proceedings of the National Academy of Sciences. [5] Hughes et al. (2019) Global warming impairs stock–recruitment dynamics of corals. Nature. [6] Dietzel et al. (2020) Long-term shifts in the colony size structure of coral populations along the Great Barrier Reef. Proceedings of the Royal Society B.[7] Cheal et. al. (2017) The threat to coral reefs from more intense cyclones under climate change. Global Change Biology."
https://science.feedback.org/review/rain-fell-on-greenland-summit-for-the-first-time-on-record-as-accurately-reported-by-cnn/,1.3,"CNN, by Rachel Ramirez, on 2021-08-19.",,"""Rain fell at the normally snowy summit of Greenland for the first time on record""",,,,,"Reviewers’ Overall Feedback: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Ted Scambos Senior Research Scientist, National Snow and Ice Data Center: It is typical for accuracy for the press – CNN and BBC and many others tend to write about climate such that the events sound more exciting, and less qualified or approximate. The main omission is that the rain event over the whole island was the largest for those days in August, and that the amount is an estimate from a model, based on weather re-analysis (which I think I explained to Rachel [Ramirez, the journalist who wrote the story on CNN]). That the overall ice sheet runoff was seven times higher than ’normal’ (1981-2010 average) is not hard to believe, because runoff tails off abruptly after the first week in August in most years. The event was a warm spike over about 50% of the island, and a lot of the southwestern slope was still in late summer mode. The statement about the crust at Summit Station forming a layer that would enhance run-off is a slight misquote: increased melting on the flanks of the ice sheet has led to thick ice layers that allow greater runoff. We should retain our stance that this was a major climate anomaly for Greenland and that the public was appropriately informed about the event — it is not an exaggeration to say it was an extreme event. The later Twitter reports of other melting events in the 1930s and 1950s do not include the Summit Station area, and that analysis of the GISP-2 and GRIP cores, and many others, show that melting (or rain, which would look like a melt event) is rare in the ‘dry snow zone’ of Greenland — hence the name. Kent Moore Professor, University of Toronto: The article is highly factual. One issue that we have is the lack of data over the Greenland Ice Sheet (both spatially and temporally). Thus some of the claims, although backed by the limited data, are valid; we can’t be sure that we may have missed similar outliers. For example, we can’t be sure that a rain event of the type described did not occur in the period before observations were made or may have occurred somewhere on the ice sheet before in a region without any observations. Xavier Fettweis Research scientist, University of Liege: The numbers and statistics given in the CNN article are based on a report from NSIDC which is: using outputs of the regional climate model MAR (from ULiège – Belgium) forced by the reanalysis ERA5 to give statistics at the scale of the whole ice sheet showing measurements (temperature and rainfall) at Summit. According to this paper, MAR is one of the internationally recognized models to quantify the surface mass balance of the Greenland ice sheet, and only outputs of models like this can give statistics such as the one listed in the CNN article.” Mira Berdahl Postdoctoral Scholar, University of Washington: This article is meant for a general audience and does well to emphasize the fairly drastic effects of climate change on the Greenland ice sheet. However, there are a few statements throughout, (e.g., global sea level rose permanently by 1.5 millimeters as a result), which I find slightly frustrating. I wouldn’t, for example, claim sea level rise is permanent (on what time scale?). Also, there should be more care taken to distinguish between rain events and melt events at the summit. I worry these could be confused if not explicitly explained. Also, I think the mention of polar bears, while interesting, is fairly tangential to this story. Overall, the story is worth getting out there, it is true that rain did fall for the first time in recorded history at the summit."
https://science.feedback.org/review/a-2014-study-showed-that-the-us-corn-belt-is-one-of-the-biggest-primary-producers-on-earth-in-july-but-didnt-show-that-it-produces-more-oxygen-than-the-amazon/,Inaccurate,"Facebook, Facebook users, 2021-09-05","""the US corn crop, at its peak, produces 40% more oxygen than the Amazon rainforest.""",,"Inaccurate: The 2014 paper “Global and time-resolved monitoring of crop photosynthesis with chlorophyll fluorescence” uses a new technique to study cropland productivity around the world, but it doesn’t examine oxygen emissions. The paper also doesn’t account for the productivity of natural ecosystems like rainforests. Therefore the paper cannot show that US Corn Belt produces more oxygen than the Amazon rainforest overall. Misleading: The 2014 paper shows that the maximum gross primary productivity (GPP) in the US Corn Belt achieved in July 2009 exceeded the GPP of any other region on Earth. The claim is misleading as it wrongly implies that the study concluded that the US Crop Belt was more productive year-round than the entire Amazon and that this productivity would result in the largest amount of oxygen emissions. ","A remote sensing technique known as sun-induced chlorophyll fluorescence is used by scientists to measure gross primary productivity—the capacity of plants to absorb carbon dioxide through photosynthesis—over large regions. A 2014 study did show that, per unit area, the US Corn Belt is the most productive cropland on Earth during summer in the northern hemisphere. However, the study did not compare the productivity of natural ecosystems with that of croplands, nor did it measure the amount of oxygen produced by these environments.","""This satellite image shows the photosynthesis of America's 100 million acre Corn crop. Further research found the US corn crop, at its peak, produces 40% more oxygen than the Amazon rainforest. Thank you farmers.""",,"Summary: A series of Facebook posts (such as this one) claiming that the United States Corn Belt produces 40% more oxygen than the Amazon rainforest went viral in September 2021. This claim is based on a 2014 study in Proceedings of the National Academy of Sciences that received wide attention at the time (see here, here, or here). The study attempted to understand how a new remote sensing technique could improve the knowledge we have of how croplands around the globe are growing and incorporating carbon from the air. This technology, called Sun-induced Chlorophyll Fluorescence, measures the emission of a small amount of near-infrared light by the chlorophyll molecule when it receives sunlight. This infrared radiation is emitted in all directions and can be detected from space by a satellite, giving the scientists an overview of how much photosynthesis is occurring on the ground at a given place and a given time. With this technique, scientists can estimate gross primary productivity, which is the amount of carbon that plants take from the atmosphere through photosynthesis to grow and develop. As the authors of the study wrote: “Here we demonstrate that new space-based observations of chlorophyll fluorescence, an emission intrinsically linked to plant biochemistry, enable an accurate, global, and time-resolved measurement of crop photosynthesis, which is not possible from any other remote vegetation measurement. Our results show that chlorophyll fluorescence data can be used as a unique benchmark to improve our global models, thus providing more reliable projections of agricultural productivity and climate impact on crop yields.” In addition to the main conclusion that this technique works well, the scientists noticed that the productivity of certain large cropland areas, such as the US Corn Belt or the Indo-Gangetic Plains in India, was underestimated in previous studies. In their study, the maximum value of sun-induced chlorophyll fluorescence worldwide is achieved in the US Corn Belt in July, at approximately 5 g CO2/m²/d. In contrast, South American croplands are estimated to produce a maximum of about 2.9 g CO2/m²/d in February (Southern hemisphere summer). Climate Feedback reached out to the first author of the study, Luis Guanter, who refuted the claim: “Our study had nothing to do with oxygen, but with plant gross primary production (GPP, amount of carbon absorbed by the plants through photosynthesis). During the June-July period the US Corn Belt shows in general higher rates of greenness (leaf chlorophyll content x plant biomass) and hence chlorophyll fluorescence (a proxy for photosynthesis) per unit surface than the Amazon forest, as it is shown in Figure 1. It is probably true that the US Corn Belt is fixing more carbon from the atmosphere in June-July than the entire Amazon forest for the same time period, since the US Corn Belt represents a large extension of high and dense plants growing at the same time.” Figure 1 – Global map of maximum monthly sun-induced chlorophyll fluorescence for 2009. From Guanter et al. (2014) The claim that the US Corn Belt is overall more productive than the Amazon is inaccurate and misleading as it wrongly implies that the study concluded that the US Crop Belt was more productive year-round than the entire Amazon and that this productivity would result in the largest amount of oxygen emissions. Conclusion: The paper determines whether the new Chlorophyll Fluorescence technique could be useful for remotely measuring cropland gross primary productivity. Using this technique, the authors observed that the US Crop Belt exhibited the highest level of productivity worldwide in July 2009. Based on this result, they concluded that the US Corn Belt holds the world record for gross primary productivity, specifically during that month. However, the paper did not study oxygen production, and there’s no evidence that these plants produce more oxygen throughout the entire year compared to other areas like the Amazon rainforest. For these reasons, the claim that the US Corn Belt is producing more oxygen than the Amazon is inaccurate and unsupported by the research it cites.Scientists’ Feedback: [Guanter is the first author of the scientific article on which the Facebook meme relied] “Our study had nothing to do with oxygen, but with plant gross primary production (GPP, amount of carbon absorbed by the plants through photosynthesis). Based on our analysis, the area-integrated GPP of the crops in the US Corn Belt is huge during their growing season (June-July), as a huge amount of highly productive plants are growing quickly and at the same time. During this June-July time, the GPP peak for the US Corn Belt seems to be higher than that of the Amazon for the same time period. Of course, this is not true anymore if we averaged for the whole year (not only June-July), and in any case, the atmospheric carbon absorbed by the crops in summer is returned to the atmosphere later through respiration.” “What we meant is that during that June-July period the US Corn Belt shows in general higher rates of greenness (leaf chlorophyll content x plant biomass) and hence chlorophyll fluorescence (a proxy for photosynthesis) per unit surface than the Amazon forest, as it is shown in this figure. It is probably true that the US Corn Belt is fixing more carbon from the atmosphere in June-July than the entire Amazon forest for the same time period since the US Corn Belt represents a large extension of high and dense plants growing at the same time. Apparently, the drop in atmospheric CO2 associated with this growth can also be seen in time series of CO2 data produced with satellites measuring concentrations of greenhouse gases. All this carbon is returned to the atmosphere after the summer. But again, there is no mention of the Amazon region in our article.”Reference Guanter et al. (2014). Global and time-resolved monitoring of crop photosynthesis with chlorophyll fluorescence. Proceedings of the National Academy of Sciences"
https://science.feedback.org/review/sea-temperatures-around-the-great-barrier-reef-have-increased-over-the-last-150-years-contrary-to-claim-at-wattsupwiththat/,Inaccurate,"Climate Change Dispatch, Climate Realism, Watts Up With That?, David Mason-Jones, 2021-08-28","""Great Barrier Reef Sea Surface Temperature: No Change In 150 Years""",,"Factually inaccurate: Over the past decades, many studies have shown that the global sea surface temperature has risen. In the Great Barrier Reef region, observations unambiguously show a warming over the past 150 years.Cherry-picking: The claim is based on a unique one-month dataset from the late 19th century. Comparing temperatures taken over the period of just one month then and now isn’t enough to conclude on an overall trend over a period of decades. In addition, measurement tools, techniques, and calibration methods have evolved since then and this needs to be taken into account. ","Over the last 150 years, global sea surface temperature has been on the rise. Given that climate is defined by the weather conditions over a long period of time, one particular month or period of a given year can be warmer (or colder) than expected (outlier). Reliably determining a long-term trend in climate change across decades requires comparing temperature measurements across decades. Differences in calibration between modern-day temperature-measuring tools and those used centuries ago also mean that they cannot be compared without accounting for those differences.","""Great Barrier Reef Sea Surface Temperature: No Change In 150 Years.  [...] If the sea surface temperature of the Great Barrier Reef has been trending upwards then a 150-year comparison should be sufficient to confirm it. When compared with today’s readings, it shows no upward trend.""",,"Review: An article written by David Mason-Jones for Wattsupwiththat claims that sea temperatures around the Great Barrier Reef have not changed over the last 150 years. The claim was repeated in another article at ClimateRealism by Anthony Watts. Together, the articles received around 7,000 interactions on social media according to CrowdTangle, a social media analytics tool. In his article, Mason-Jones bases his claims on a post published by Dr. Bill Johnston in his blog. Johnston, a former research scientist at the New South Wales Department of Natural Resources, uncovered an old dataset from 1871 recorded by a marine expedition along the Australian coastline. This dataset, Johnston claims, exhibits the same temperature as measured in current times, which he thinks proves that the sea surface temperature did not change and therefore that global warming is not threatening the Great Barrier Reef. However, Johnston’s conclusion that sea surface temperatures haven’t changed is incorrect. Measurements by both the Australian Bureau of Meteorology and the Hadley Centre for Climate Prediction and Research[1] show that the sea surface temperatures are rising around the world, including around the Great Barrier Reef. The temperature anomalies averaged globally and in the Great Barrier Reef region are shown in figure 1 below.Figure 1 – Sea surface temperature anomalies over the last century in the Great Barrier Reef region (top) and globally (bottom). Anomaly values are defined with respect to the 1961-1990 temperature mean. (Source: Bureau of Meteorology) In addition to these direct temperature measurements, other observations confirm that the ocean has warmed[2]: geographical areas with a given temperature and precipitation type, or climate zones, are shifting towards the high latitudes (northward in the northern hemisphere, southward in the southern)[3], fish species distribution, seabirds migration patterns, or sea turtle breeding periods are changing, and more and more coral reefs are bleaching[4]. All these observations are consistent with a warming of the ocean and inconsistent with the claim that seawater temperature has not changed for 150 years. Thanks to this very large body of evidence, the IPCC was able to conclude in its latest assessment report that: “it is now very likely that global mean Sea Surface Temperature changed by 0.88°C from 1850-1900 to 2011-2020, and 0.60°C from 1980 to 2020. The tropical ocean has been warming faster than other regions since 1950, with the fastest warming in regions of the tropical Indian and western Pacific Oceans”[5]. Furthermore, the method used by Dr. Johnston to come to his conclusion is flawed. As Ken Caldeira, senior scientist at the Carnegie Institution for Science, explains: “One cannot establish trends in variable systems with single measurements, [especially when] somebody made measurements in 1871 with a thermometer that may or may not have been appropriately calibrated.” In other words, the measurements used by Dr. Johnston, which were taken 150 years ago, are likely to be affected by specific biases (for example, biases that arise due to the method of measurement[6]), and such biases aren’t accounted for in his comparisons with modern-day measurements. Furthermore, measurements that were taken over a period of one month wouldn’t reliably represent temperature changes over a period of several decades. Because outliers happen, certain periods in time may be warmer or cooler than expected. Temperature records from a single month that could have been particularly warm aren’t reliable evidence of any overall, long-term trend.Scientists’ Feedback: Ken Caldeira Senior Scientist, Carnegie Institution for Science: David Mason-Jones and Bill Johnston are apparently arguing that because somebody took a measurement in 1871 with a thermometer that may or may not have been appropriately calibrated, that decades of observations with carefully calibrated instruments should be ignored. Further, assuming the measurements of 150 years ago were done well, a warming trend over the past 150 years is entirely consistent with a warm month 150 years ago. One cannot establish trends in variable systems with single measurements. I do like to respect expertise. The temperature records developed by NOAA and other organizations were developed by teams of (mostly) Ph.D. scientists who publish their methods and results in peer-reviewed journals. If Bill Johnston wants his theories to be taken seriously, he should write them up and submit them to a high-quality peer-reviewed journal. It is typical of conspiracy theorists to say they can’t get their work published because there is a vast conspiracy trying to suppress the truth. On the other hand, it might just be the case that amateur conspiracy theorists are wrong.REFERENCES: 1 – Rayner (2003) Global analyses of sea surface temperature, sea ice, and night marine air temperature since the late nineteenth century. Journal of Geophysical Research 2 – Lough and Hobday (2011). Observed climate change in Australian marine and freshwater environments. Marine and Freshwater Research. 3 – Lough (2008). Shifting climate zones for Australia’s tropical marine ecosystems. Geophysical Research Letters 4 – Poloczanska et al. (2007). Climate change and Australian marine life. Oceanography and marine biology 5 – Fox-Kemper et al. (2021) Ocean, Cryosphere and Sea Level Change. In: Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press 6 – Smith and Reynolds (2002). Bias corrections for historical sea surface temperatures based on marine air temperatures. Journal of Climate "
https://science.feedback.org/review/solar-forcing-is-not-the-main-cause-of-current-global-warming-contrary-to-claim-by-alex-newman-in-the-epoch-times/,Incorrect,"Newsmax, The Epoch Times, The Western Journal, Alex Newman, 2021-08-16",The Sun and not human emissions of carbon dioxide may be the main cause of warmer temperatures in recent decades. There is a systemic bias in UN IPCC's data selection.,,"Incorrect: Solar irradiance variations have a very small impact on Earth’s current climate change. There is a very large consensus of scientific evidence showing that human emissions of greenhouse gases are the main cause of current climate change. The hypothesis that the Sun is responsible for climate change is inconsistent with real-world observations. Misleading: There’s no evidence that the IPCC’s conclusions are the result of bias. The scientific consensus about the cause of climate change is built on a significant number of publications (many thousands for the IPCC reports, for example), decades of studies, and methods that are shared and accepted by the scientific community.","Changes in solar irradiance have a very small influence on current climate compared to the effect induced by CO2 and other greenhouse gases. Ideas, methods and data sets used by scientists to study the various climate drivers are frequently discussed in the scientific literature and in the IPCC reports. Based on the body of evidence available, the scientific community concluded that solar variations don’t have any noticeable influence on the climate change observed in recent decades.","The change in the Sun’s irradiance are a plausible and important factor that can explain most of the observed changes in the thermometer data [and] depending on which published data and studies you use, you can show that all of the warming is caused by the sun. There is a systemic bias in UN IPCC's data selection.","1 – Lockwood & Fröhlich (2007). Recent oppositely directed trends in solar climate forcings and the global mean surface air temperature. In Proceedings of the Royal Society of London A: Mathematical, Physical and Engineering Sciences. 2 – Solanki et al. (2004). Unusual activity of the Sun during recent decades compared to the previous 11,000 years. Nature. 3 – Lean & Rind (1999). Evaluating sun–climate relationships since the Little Ice Age. Journal of Atmospheric and Solar-Terrestrial Physics. 4 – Lockwood (2008). Recent changes in solar outputs and the global mean surface temperature. III. Analysis of contributions to global mean air surface temperature rise. In Proceedings of the Royal Society of London A: Mathematical, Physical and Engineering Sciences. 5 – Santer et al. (2013). Human and natural influences on the changing thermal structure of the atmosphere. Proceedings of the National Academy of Sciences. 6 – Hegerl & Wallace (2002) Influence of patterns of climate variability on the difference between satellite and surface temperature trends. Journal of Climate. 7 – Bindoff, et al. (2013) Detection and attribution of climate change: From global to regional. Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change 8 – USGCRP, 2017: Climate Science Special Report: Fourth National Climate Assessment, Volume I [Wuebbles et al.]. U.S. Global Change Research Program. 9 – Doran & Zimmerman (2009) Examining the scientific consensus on climate change. Eos, Transactions American Geophysical Union. 10 – Anderegg et al. (2010) Expert credibility in climate change. Proceedings of the National Academy of Sciences. 11 – Cook et al. (2013) Quantifying the consensus on anthropogenic global warming in the scientific literature. Environmental research letters. 12 – Verheggen et al. (2014) Scientists’ views about attribution of global warming. Environmental science & technology. 13 – Cook et al. (2016) Consensus on consensus: a synthesis of consensus estimates on human-caused global warming. Environmental Research Letters. 14 – IPCC, 2013: Summary for Policymakers. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Stocker et al. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. Figure SPM.5 15 – IPCC, 2021: Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Masson-Delmotte et al.]. Cambridge University Press. In Press.","The claim that the Sun and not human emissions may be the main cause of warmer temperatures in recent decades has been made in a newspaper article written by Alex Newman and published in The Epoch Times on 16 August 2021. The article and its claims have been repeated in several articles including one at Newsmax. In the Epoch Times article, Newman additionally claimed that a new scientific paper proves a systematic bias in the International Panel on Climate Change (IPCC)’s workflow, accusing it of supporting an unscientific agenda and ignoring data that contradict a “chosen narrative”. But solar irradiance cycles and its influence on the climate are well-understood by scientists and the evidence shows clearly that solar variability cannot account for the recent climate change[1-3]. The Sun’s activity has been monitored since the beginning of the 20th century, and even if its irradiance (the amount of solar energy reaching the Earth) shows important yearly fluctuations, statistically it hasn’t shown an overall increase in the last decades (Figure 1 below). On the contrary, irradiance has decreased since the 60s (see the graph below) while global temperature increased, proving the lack of correlation between the two variables[4], and undermining the claim made in Newman’s article and the authors of the study he cited. Figure 1 – Comparison of the global surface temperature changes (red) and the Sun’s energy that Earth receives (yellow) in watts per square meter since 1880. One can see that since the 1960s, the global temperature and solar activity have varied in opposite directions. Source: NASA/JPL-Caltech Another line of evidence to consider is that if variations in the Sun’s irradiance were the cause of recent warming at the surface of the Earth, the entire atmosphere should see its temperature change accordingly, including the upper layers. But this is not what the scientific community observed. As the scientific literature[5-7] and satellite data show (see Figure 2), the temperature in the lower stratosphere (high altitude) falls while the temperature of the lower troposphere (low altitude) rises. This observation invalidates the hypothesis that the Sun is the driving factor of the global surface temperature increase we observe while it is consistent with the hypothesis that greenhouse gases are the cause. Figure 2 – Data from the Met Office Hadley Center showing global temperature variations in the upper atmosphere (top graph) and in the lower atmosphere (bottom graph) since the 1960s. We observe a warming at the surface and a cooling above, which is consistent with the effect of added greenhouse gases in the atmosphere and inconsistent with the hypothesis of a solar influence. Contrary to what is claimed by Newman and his guests about its supposed bias against the solar hypothesis, the IPCC is mandated to compile the knowledge produced by the entire scientific community and cautiously evaluate the scientific merit of any new contribution. Therefore contributing scientists consider every potential cause of climate change, including anthropogenic (human-caused) and natural causes. As mentioned in the U.S. Fourth National Climate Assessment[8], “between 93% to 123% of observed 1951-2010 warming was due to human activities” as shown in Figure 3 below. That anthropogenic factors can explain up to 123% of the warming observed is due to the fact that there are also cooling effects of some drivers, such as volcanic eruptions or changes in land use. The cooling effects compensate for some of the warming effects of increased atmospheric CO2 concentration by human emissions. This shows that natural forcings are accounted for in the IPCC’s or U.S. National Climate Assessment’s reports, solar forcings simply happen to be weaker. Figure 3 – Time evolution in effective radiative forcings (ERFs) across the industrial era for anthropogenic and natural forcing mechanisms. The ERF measures the net heat gain or loss in the Earth’s climate system. Well-mixed greenhouse gases (WMGHG) are the long-lived gases that have a strong impact on climate and include carbon dioxide, methane, nitrous oxide, and different kinds of chlorofluorocarbons. From the U.S. Fourth National Climate Assessment[8]. The same considerations are taken into account in the latest IPCC report, where all the forcing factors are compiled and their specific contributions assessed (see Figure 4). As mentioned in the sixth IPCC assessment report, compared to 1750, solar (-0.02 W/m²) driver is considered as very minor compared to carbon dioxide (+2.16 W/m²). Figure 4 – Observed warming contribution for each kind of driver. We can see that part of the global warming caused by human emission is masked by an aerosol effect. Details can be found in the last IPCC Summary: for Policymakers[15]. In the Epoch Times article, Newman also claims that “scientific views have been deliberately suppressed by the IPCC”, “that data sets are being selected that support the IPCC view while data contradicting it have been excluded”. A review of the literature shows that an overwhelming majority of scientists agree with the conclusions that the IPCC releases every five years in their Assessment Reports. This scientific consensus has been consistently measured for more than a decade[9-13]. The citation in the last IPCC report of a paper written by Connolly, who is attacking the IPCC for its supposed “confirmation bias” in Newman’s article, shows that relevant research papers are scientifically evaluated and duly considered. The ACRIM (Active Cavity Radiometer Irradiance Monitor) data sets that Newman and his guests claim were ignored by the IPCC appear in numerous studies cited in the report (the acronym itself is used 14 times in the fifth assessment report published in 2013[14]). It is notably written in this report that there is a reason why the signal produced by ACRIM exceeds the other sources for the Sun irradiance measurements, which may be a reason why it is no longer used as a reference: “The increase in excess of 0.04% over the 27-year period of the ACRIM irradiance composite, although incompletely understood, is thought to be more of instrumental rather than solar origin. The irradiance increase in the ACRIM composite is indicative of an episodic increase between 1989 and 1992 that is present in the Nimbus 7 data.”Scientists’ Feedback: Timothy Osborn Professor, University of East Anglia, and Director of Research, Climatic Research Unit: [This comment comes from a previous review of a similar claim.] There is strong evidence that solar forcing cannot explain much of the observed warming at all. The “fingerprint” of solar forcing does not match the observed changes at all, neither over time nor space. Solar forcing would warm both the stratosphere and the surface of the Earth, whereas CO2 warms the surface (and the troposphere) but cools the stratosphere. Using radiosondes and (more recently) satellites, we have observed a warming surface and troposphere together with a cooling stratosphere. See Santer et al (2013)[5] for one of many studies providing this evidence. Figure 5 – Zonal-mean atmospheric temperature trends in satellite observations from January 1979 to December 2012 showing warming of the lower atmosphere (troposphere) and cooling of the upper-atmosphere (stratosphere), from Santer et al (2013)[5] Britta Voss Postdoctoral Research fellow, U.S. Geological Survey: [This comment comes from a previous review of a similar claim.] Solar forcing is much smaller than CO2 forcing. As this figure from the latest IPCC report shows, CO2 radiative forcing (1.68 W/m2) dwarfs solar forcing (0.05 W/m2). Along with other greenhouse gases, CO2 dominates the total radiative forcing when all positive and negative factors are taken into account. Figure 6 – Radiative forcing estimates in 2011 relative to 1750. Values are global average radiative forcing, partitioned according to the emitted compounds or processes that result in a combination of drivers. Source IPCC AR5 Patrick Brown, Assistant Professor, San Jose State University: [This comment comes from a previous review of a similar claim.] Careful analysis that attempts to take into account all major factors and their evolution in time indicates that anthropogenic increases in greenhouse gasses account for more than 100% of the observed warming on the century timescale (requiring cancellation from cooling influences). See the summary graphic from Carbon Brief, below."
https://science.feedback.org/review/despite-2021-being-a-good-year-for-coral-health-coral-in-the-great-barrier-reef-has-declined-over-the-past-decade-and-is-threatened-by-climate-change-contrary-to-claims-by-peter-ridd/,Inaccurate,"Climate Change Dispatch, The Australian, Watts Up With That?, Peter Ridd, 2021-07-21",“The amount of coral on the Great Barrier Reef is at record high levels”; those claiming the reef is threatened by climate change are alarmists,,"Inaccurate: Numerous scientific studies show a decrease, not an increase, in coral growth over the past decade. International scientific organizations are not ignoring the improvement in coral communities, and acknowledge the influence of periods with low disturbance on the ability of damaged reefs to recover. Misrepresents source: Peter Ridd misuses data from the Australian Institute of Marine Science in a graph showing how coral cover in the Great Barrier Reef has changed over time. Although the data show an improvement in the amount of coral covering the reef in 2021 compared to previous years, coral cover is not at a record high since 1985 for any region of the Great Barrier Reef.","Coral reefs comprise a small, but invaluable oceanic ecosystem, because they provide protection from storms and sturges, host wildlife, are a dense source of food and have a strong economic value for local communities. The growth rate and overall health of coral reefs are very sensitive to environmental conditions, including water temperature, pH, and extreme weather events. Warming water temperatures and increasing CO2 concentrations in the ocean often cause coral bleaching events, eventually resulting in the death of large fractions of numerous coral reefs around the world. However, some coral reefs can recover from these extreme events and adapt to changing conditions if they are given enough time and the appropriate conditions. ","“The amount of coral on the Great Barrier Reef is at record high levels”; “Coral growth rates have, if anything, increased over the past 100 years”; those claiming the reef is threatened by climate change are alarmists",,"The claim that the amount of coral in the Great Barrier Reef has increased over the past century and reached a record high in 2021 was published on 23 July 2021 in an article published by Peter Ridd, a former physicist at James Cook University. The article was published on several websites, including Climate Change Dispatch, Watts Up With That, and The Australian, and together received more than 10,000 interactions on social media according to the social media analytics tool Crowdtangle. In the article, Ridd claims that the release of the latest annual report of the Australian Institute of Marine Sciences on the Great Barrier Reef shows a record high level of coral covering the reef. He uses this observation to claim that scientists who state that coral reefs are threatened by climate change are alarmists. These claims are not supported by scientific evidence and are based on misrepresentations of scientific data and a flawed understanding of coral reef science. For example, Ridd shows a figure allegedly from the latest Australian Institute of Marine Science (AIMS) report to support his claim that the amount of coral in the Great Barrier Reef reached a record high in 2021, but Ridd’s figure is neither consistent with the figures published in the AIMS report[1], nor with the scientific literature. Contrary to the claim, the recent AIMS report for the three regions of the Great Barrier Reef showed strong variation in coral cover across years, but no record high in 2021, as claimed in Ridd’s article (see Figure 1). Furthermore, scientific studies show a significant decrease in the amount of coral and coral growth rate since the 1980’s[2-5]. Moreover, scientific studies consistently show that the amount of coral cover and the growth rate of coral are negatively impacted by global warming. As stated in De’ath et al. (2012)[2], “over 1985-2012, […] we show a major decline in coral cover from 28% to 13.8% (0.53%/y), a loss of 50.7% of initial coral cover.” In addition, as described in van Woesik et al.[3], “Recent increases in temperatures appear to have caused the slowing of coral growth rates on the near shore Great Barrier Reef, from an average of 15.2 mm/yr in 1988 to 12.8 mm/yr in 2003, a decline of 1.02%/yr, which has been attributed to a corresponding increase in sea-surface temperature”. Figure 1 – Comparison between Ridd’s figure (top) and the data from the AIMS report (bottom) with data given for each of the three Great Barrier Reef regions showing no record high nor historic maximum in 2021. In his article, Ridd also claims that scientists “generally downplayed or ignored” the reefs capacity to recover from bleaching or extreme weather events, however, scientific studies on coral reefs acknowledge the capability for the reefs to recover and grow after such events[7-9]. Doing so, Ridd neglects to address the complexity of the coral reef diversity, species dynamics and differences around the globe, and misleads the reader into thinking scientists ignore these facts. As discussed in the AIMS report, the main hypothesis for the rapid recovery of the Great Barrier reefs during 2021 is that “2021 has been a low disturbance year”, and that a strong increase in fast growing Acropora corals created a shift in the population distribution of coral. These species easily colonize new territory and grow quickly, but they are also more susceptible to wave damage, coral bleaching, and predators, meaning that even if coral cover increases, the reef has not totally recovered from the last bleaching events. Peter Ridd also claims, “The science institutions have been claiming that there have been three disastrous bleaching events in the past five years, which does not accord with the latest statistics,” and, “while there have been three events, they occurred in largely different regions in each year. The reef has thus effectively had one major bleaching event in the past five years and the previous major event was in 2002.” Ridd’s statements are contradictory and misleading. Scientists identified five global coral bleaching events in the Great Barrier Reef over the last decade, which occurred in 2010, 2015, 2016, 2017 and 2020. Some scientists group the worldwide bleaching events from 2015 to 2017 into a single one, but others consider them to be independent events given the differences in intensity and geographic characteristics of events in 2016 and 2017 (see the figure below). These data confirm the occurrence of three distinct coral bleaching events in the Great Barrier Reef over the last five years[10]. One can see on the map that several reefs have been affected by two or even the three bleaching events. Figure 2 – Maps of the last three bleaching events that occured on the Great Barrier Reef. From ARC Centre for Excellence in Coral Reef Studies Finally, Ridd states that scientists use these bleaching events to spread a message of doom, hypothetically ignoring the “real” state of the Great Barrier and preparing headlines to deceive the public about the risks of climate change. Almost all coral reef scientists agree that climate change will affect coral reef health and resilience[11], it is wrong to claim that the messages scientists try to convey are of doom. As specified by the latest IPCC report about coral reefs, it is known with high confidence that ocean warming and acidification will “enhance the reef dissolution, affect the coral species distribution and lead to community change”[11]. The main message that the scientific community conveys is that coral reefs will continue to be endangered if environmental conditions keep changing in the shallow waters where most coral reefs live. As Box 5.5 in the latest IPCC report states: “Altogether, coral reefs of the future will not resemble those of today because of the projected decline and changes in the composition of corals and associated species in the remaining reefs (high confidence). The very high vulnerability of coral reefs to warming, ocean acidification, increasing storm intensity and Sea Level Rise under climate change (AR5 WG2), including enhanced bioerosion (high confidence) point to the importance of considering both mitigation and adaptation for coral reefs”[11]. For decades, scientists have highlighted the fact that coral reefs are very sensitive to their direct environmental conditions, and that if the water temperature increases and the pH of the sea water keeps changing due to global warming, corals will bleach and die faster than they can regenerate. According to two Australian coral reef specialists, coral reefs are capable of resilience, and they can recover from extreme events and bleaching if given enough time. Professor Terry Hughes, director of the Centre of Excellence for Coral Reef Studies at James Cook University, stated in a 2020 Guardian article, “It’s not too late to turn this around with rapid action on emissions…But business-as-usual emissions will make the Great Barrier Reef a pretty miserable place compared to today.” David Wachenfeld, chief scientist at the Great Barrier Reef Marine Park Authority added in the same article, “No one climate event will kill the Great Barrier Reef, but each successive event creates more damage. Its resilience is not limitless, and we need the strongest possible action on climate change.”LEARN MORE If you want to read more about coral reef recovery, bleaching events or other fact-checked claims made by Peter Ridd, you can follow these links : A fact-check article on a very similar claim made by Peter Ridd in 2019 The Australian Coral Reef Society’s statement regarding Ridd’s “questionable claims”REFERENCES: [1] Annual Summary: Report of Coral Reef Condition 2020/2021. (2021). Australian Institute for Marine Science. [2] De’ath et al. (2012). The 27–year decline of coral cover on the Great Barrier Reef and its causes. Proceedings of the National Academy of Sciences, 109(44), 17995-17999. [3] van Woesik et al. (2015) Keep up or drown: adjustment of western Pacific coral reefs to sea-level rise in the 21st century.Royal Society Open Science.2: 150181. [4] Anderson et al. (2017) Variation in growth rates of branching corals along Australia’s Great Barrier Reef. Scientific Reports 7, 2920. [5] Davis et al. (2021) Global coral reef ecosystems exhibit declining calcification and increasing primary productivity. Communications Earth & Environment 2, 105. [6] Cooper et al. (2008) Declining coral calcification in massive Porites in two nearshore regions of the northern Great Barrier Reef. Global Change Biology.14, 529–538. [7] Roth et al. (2018). Coral reef degradation affects the potential for reef recovery after disturbance. Marine Environmental Research, 142, 48-58. [8] Hoegh-Guldberg (2006). Complexities of coral reef recovery. Science, 311(5757), 42-43. [9] Gilmour et al. (2013). Recovery of an isolated coral reef system following severe disturbance. Science, 340(6128), 69-71. [10] Eakin et al. (2019) The 2014–2017 global-scale coral bleaching event: insights and impacts. Coral Reefs 38, 539–545. [11] IPCC Special Report Ocean & Cryosphere section 5.3.4 p 507 and box 5.5 p 539-540"
https://science.feedback.org/review/youtube-video-falsely-claims-that-climate-models-systematically-over-estimated-warming-and-that-we-are-heading-towards-an-ice-age/,Inaccurate,"Suspicious0bservers, Ben Davidson, 2021-05-05","""The official observed temperatures are coming consistently below the scary global warming numbers""; ""Melting polar ice triggers ice age""",,"Inaccurate: The claim that climate models consistently overestimate global warming is inaccurate. Retrospective studies have found that climate models skillfully forecasted the evolution of global surface temperatures over the past few decades.  Misrepresents sources: Ben Davidson quoted numerous studies to support his claim. However, he misrepresented these sources: the analyses did not conclude that models are inaccurate, nor that an ice age would be coming. ",Climate scientists use models to simulate Earth's climate system and project the rate of global warming caused by human activities. State-of-the-art climate models have successfully forecasted global average surface temperatures over the past few decades.,"""The official observed temperatures are coming consistently below the scary global warming numbers""; ""Models fail to predict the future and the past due to bias, uncertainties, questionable data and unappreciated natural forcing""; ""Melting polar ice triggers ice age""",,"The claim that climate models fail to predict the future or reproduce the past was published in a YouTube video by Ben Davidson on his channel, Suspicious0bservers, which has more than 500,000 subscribers. This video has been watched more than 57,000 times since it was published on May 5, 2021. In the video, Davidson makes numerous false claims about climate models as explained in this review. He shows screenshots of titles and abstracts from recent climate science publications, which he misinterpreted to support his conclusion. The core claim of the video is that “At no point have the climate models accurately predicted the future. The official observed temperatures are coming consistently below the scary global warming numbers”. However, this claim is contradicted by the fact that scientists found climate models skillfully forecast the evolution of global surface temperatures over the past few decades (see a previous Climate Feedback review here). For example, a 2019 study by Hausfather et al. found that climate models published between 1970 and 2007 “were generally quite accurate in predicting global warming in the years after publication, particularly when accounting for differences between modeled and actual changes in atmospheric CO2 and other climate drivers”[1] (read scientists’ comments belowfor further information). To support his claim that scientists overestimate global warming, Davidson argues that climate models are too sensitive to CO2, which means that the increase in global temperature forecasted for a given increase in atmospheric CO2 concentration is too high. Davidson refers to a 2020 study by Zhu et al. which shows that a recent climate model doesn’t accurately forecast past temperatures from the Eocene (50 millions years ago), predicting much warmer temperatures at the time than expected[2]. Scientists understand that some, but by no means all, of the most recent climate models show a high equilibrium climate sensitivity, which is defined as the long-term response of global mean surface temperature to a doubling of atmospheric CO2 concentrations[3]. This sensitivity to CO2 is poorly constrained, with a likely range of 1.5°C to 4.5°C, according to the IPCC Fifth Assessment Report. It’s a fact that some of the latest climate models have a sensitivity higher than 4.5°C, with values up to 5.6°C[3, 4].For example, the model tested in the Zhu et al. study has a sensitivity of 5.3°C. As a result, these models simulate stronger warming and have difficulties reproducing the observed warming trend. However, according to a 2020 study by Tokarska et al., this is the case for only a third of the models participating in the Sixth Coupled Model Intercomparison Project (CMIP6), which will form the basis for the upcoming Sixth Assessment Report of the IPCC[3]. Conversely, other CMIP6 models with climate sensitivity values that are within the IPCC likely range show global warming trends that are consistent with past global temperature observations. Moreover, as this study shows, “projected future warming is correlated with the simulated warming trend during recent decades, enabling us to constrain future warming based on consistency with the observed warming”. The study concludes that, taking this into account, “observationally constrained CMIP6 warming is consistent with previous assessments based on CMIP5 models”. Later on in the video, Davidson claims that, “recently half of Arctic warming was blamed on ozone loss… It told us that the heat that has been blamed on carbon all these years is a fantasy”. To support his claim that CO2 is actually not responsible for global warming, he displays a 2020 paper by Polvani et al. demonstrating that chemicals that destroy the ozone layer, such as chlorofluorocarbon (CFC’s), contributed to warming in the Arctic[5]. While it is true that these ozone depleting substances have the potential to warm the atmosphere, their effect on Arctic temperatures is weaker than the one induced by CO2 rising concentration, contrary to Davidson’s interpretation. As the authors of the study warn, “it is important to place ozone depleting substances in the context of the other anthropogenic forcings. The largest radiative forcing is associated with CO2, and it is three times larger than the radiative forcing from ozone depleting substances, over the 1955–2005 period” (see the figure below). Radiative forcing (RF) describes the net change in the energy balance of the Earth system in response to some imposed perturbation (for example, a change in CO2 concentration in the atmosphere). It is expressed in watts per square meter and averaged over a period of time, with positive RF leading to a warming and negative RF to a cooling. Radiative forcing is valuable for comparing the influence on global mean temperature of most individual agents affecting Earth’s radiation balance (e.g. specific greenhouse gases, aerosols, solar irradiance). Figure 1—Radiative forcing of greenhouse gases for 1955-2005. From Polvani et al. (2020)[5]Another misleading claim made by Davidson is that “the data itself has come under major questions by the world’s number one climate journal… The urban heat island effect adds on a major source of doubt…”. In this statement Davidson is suggesting that the rise in global temperature recorded is inaccurate and biased by the fact that temperatures are “naturally” getting higher in the cities due to urbanization. According to him, global warming is thus overestimated. He relies on a study by Zhang et al. published in March 2021 in Journal of Climate that quantifies the urbanization contribution on global land annual mean and extreme temperature records[6]. Cities do experience much warmer temperatures than nearby rural areas, especially at night or in winter, because urban building materials trap heat. This phenomenon is called Urban Heat Island (UHI). This urbanization effect influences temperature measurements locally, and scientists are well-aware that it needs to be properly identified and removed in temperature data series in order to ensure that global warming is accurately measured and not overestimated. According to the IPCC Fifth Assessment Report, “global adjusted data sets likely account for much of the UHI effect present in the raw data”[7]. Overall, adjustments to temperature data reduce the apparent global warming. At the global scale, the IPCC report argued that the uncorrected urbanization influences contribute no more than 10% to the centennial global land averaged temperature trends. As described in Zhang et al., “the urbanization effect on the trends of annual mean and extreme temperature indices series in East Asia is generally the strongest, which is consistent with the rapid urbanization process in the region over the past decades, but it is generally small in Europe during the recent decades”. After discrediting climate models predicting future global warming, Davidson claims that “the changes we are seeing are going to trigger an ice age. Melting the ice at the pole affects the heat transport in the ocean and triggers rapid cooling towards ice-age conditions”. He cites a study by Starr et al. published in January 2021 that links the melting of Antarctic icebergs and the onset of glacial periods[8]. This claim is inaccurate and misrepresents the results of the study it is based on. As discussed belowby Ian Hall, from Cardiff University, a co-author of the study, the study’s conclusion doesn’t apply in the warm conditions we are currently experiencing. On the contrary, the natural rhythm of ice age cycles may be disrupted as the Southern Ocean will likely become too warm for Antarctic icebergs to travel far enough to trigger the changes in ocean circulation required for an ice age to develop. This pattern is the exact opposite of the claim made by Davidson. The second part of the video is devoted to the claim that “climate has much more to do with sun, volcanoes and cosmic rays modulation than is allowed in the climate models”. This statement is inaccurate as there is strong evidence that solar forcing cannot explain much of the observed warming at all (see below , and previous Climate Feedback reviews here and here). Scientist’s Feedback: “At no point have the climate models accurately predicted the future” Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: [Comment from a previous evaluation of a similar claim] While models can never be a perfect representation of the Earth’s system, they do an excellent job of reproducing many aspects of the Earth’s climate, from rainfall and wind patterns to storm and hurricane formation and warming of the climate. In a 2019 paper we evaluated the performance of 17 historical climate model projections published between 1970 and 2001[1]. We found that 10 of those 17 projected a rate of future temperature change nearly identical to what actually happened in the real world in the years after they were published, while four of the models projected too much warming and three models too little warming[1]. This is particularly impressive for the 1970s-era models, which were published at a time when evidence of observed global warming was limited (and some even thought – based on limited observations – that the world was modestly cooling). Figure 2—Observed surface temperature change (HadCRUT5 – black line) compared to climate model projections from the years after the model was published (colored lines). Adapted from Hausfather et al. 2019 [1].“Oversensitivity to CO2” [Comment from a previous evaluation of a similar claim.] We and others have shown recently that almost all of the high climate sensitivity models in fact tend to overestimate recent warming[3], and taking that into account suggests that many of the new CMIP6 models are biased high, and that future warming is similar to what it was in earlier models. While it is correct that we are seeing models with high climate sensitivity, the evidence is growing that there are issues with at least some of these models. [Comment from a previous evaluation of a similar claim.] It is correct that the most recent versions of some climate models estimate more warming for a given increase in CO2 concentrations. It is also correct that how clouds are represented in these models is the likely reason for these higher estimates. However, it does not report all the science available on this topic and its claims are thus misleading. Available studies that have looked at what these new model projections mean have found that models with higher warming are worse in capturing global warming trends over the past decades, making their projections of very high warming less probable[9]. This is an important context that was omitted. [Comment from a previous evaluation of a similar claim.] The most advanced, state-of-the-art predictions of the sensitivity of Earth’s climate to increasing carbon dioxide are based on multiple lines of evidence: observations, the paleoclimate record, theory, and models of varying complexity[10]. Based on this evidence, climate scientists estimate a likely range of the planetary warming resulting from a doubling of atmospheric carbon dioxide: 2.6-3.9 C (or 4.7-7 F). Climate models produce a wider range of the severity of planetary warming in response to increasing carbon dioxide[11]. This is primarily because their simulation of cloud processes is highly variable, with some models performing better or worse than others. However, a variety of independent evidence taken together reveals how clouds throughout the planet will likely behave as the climate warms, allowing scientists to predict future temperature changes with more precision than climate models simulate[10].“Data itself has come under major questions” Jennifer Francis Senior Scientist, Woods Hole Research Center: [Comment from a previous evaluation of a similar claim] Adjustments are made for good reasons. One of the most common ones is toaccount for a station located in a growing city, where the urban heat island effect would add spurious warming. In most cases the adjustments reduce, not increase, the warming in the record. Victor Venema Scientist, University of Bonn, Germany: [Comment from a previous evaluation of a similar claim] The adjustments are scientifically important, but rather modest for the global mean temperature.The adjustments make the estimated warming smaller, not larger. Below are, for example, the raw and adjusted warming signals of the NASA GISS dataset. The how and why is discussed in this post. For example, if the surrounding of a station becomes more urban this often causes a warming that is local and needs to be removed to estimate the amount the world has truly warmed. Figure 3— Evolution of raw (red line) and adjusted (black line) temperatures. From Gavin Schmidt.“The changes we are seeing are going to trigger an ice age” Ian Hall Professor, Cardiff University: [Comment from a previous evaluation of a similar claim] Our paper is unambiguous and not relevant for modern/future climate change in this way, and reporting it as so is fundamentally misinterpreting our findings. In fact, in the press release for the study, we emphasise that our findings are specifically related to natural “Milankovitch” cycles in orbital forcing, however with current human greenhouse-gas emissions and increasing global temperatures, the Southern Ocean is likely too warm for icebergs to be transported as described in the paper and melt in the regions necessary for the chain of events we highlight to be triggered. Our study does not say or imply that an ice age is coming. It does emphasise the importance of understanding iceberg trajectories and melt patterns in developing the most robust predictions of their future impact on ocean circulation and climate. Moreover, it is well established that the onset of a glacial period has only ever, and can only ever, occur when atmospheric CO2 is below a certain threshold. When atmospheric CO2 concentration is too high, the orbital forcing which favours an ice age is simply not enough to cause an ice age. Under the current orbital configuration, a CO2 concentration of below pre-industrial levels would be required for an ice age to begin[12].“The climate has much more to do with sun, volcanoes and cosmic rays modulation” Peter Neff Assistant Research Professor, University of Minnesota: [Comment from a previous evaluation of a similar claim] This is easily disproven. Solar variability does not exert warming that matches observed temperature increases. See US National Climate Assessment 4, Figure 2.1 below. Figure 4— Human and natural influences on global temperatures. From US National Climate Assessment.REFERENCES: 1 – Hausfather et al. (2019) Evaluating the Performance of Past Climate Model Projections. Geophysical Research Letters. 2 – Zhu et al. (2020) High climate sensitivity in CMIP6 model not supported by paleoclimate models. Nature Climate Change 3 – Tokarska et al. (2020) Past warming trend constrains future warming in CMIP6 models. Science Advances. 4 – Meehl et al. (2020) Context for interpreting equilibrium climate sensitivity and transient climate response from the CMIP6 Earth system models. Science Advances. 5 – Polvani et al. (2020) Substantial twentieth-century Arctic warming caused by ozone-depleting substances. Nature Climate Change. 6 – Zhang et al. (2021) Urbanization Effects on Estimates of Global Trends in Mean and Extreme Air Temperature. Journal of Climate. 7 – IPCC Fifth Assessment report. Observations : Atmosphere and Surface. 8 – Starr et al. (2021) Antarctic icebergs reorganize ocean circulation during Pleistocene glacials. Nature. 9 – Andrews et al. (2020) Historical simulations with HadGEM3‐GC3.1 for CMIP6. Journal of Advances in Modeling Earth Systems. 10 – Sherwood et al. (2021) An Assessment of Earth’s Climate Sensitivity Using Multiple Lines of Evidence. Review: of Geophysics. 11 – Zelinka et al. (2020) Causes of Higher Climate Sensitivity in CMIP6 Models. Geophysical Research Letters. 12 – Tzedakis et al. (2012) Determining the natural length of the current interglacial. Nature Geoscience."
https://science.feedback.org/review/gregory-wrightstone-article-in-the-washington-times-presents-list-of-false-and-misleading-statements-about-the-impacts-of-co2-and-climate-change-co2-coalition/,-1.8,"The Washington Times, CO2 Coalition, by Gregory Wrightstone, on 2021-04-21.",,"""There is no climate emergency""",,,,"1 – Hughes et al. (2017) Coral reefs in the Anthropocene. Nature. 2 – Hughes et al. (2017) Global warming and recurrent mass bleaching of corals. Nature. 3 – Brierley and Kingsford (2009) Impacts of Climate Change on Marine Organisms and Ecosystems. Current Biology. 4 – Handmer et al. (2012) Chapter 4 – Changes in Impacts of Climate Extremes: Human Systems and Ecosystems. Special Report of the IPCC. 5 – Gasparrini et al. (2015) Mortality risk attributable to high and low ambient temperature: a multicountry observational study. The Lancet. 6 – Gasparrini et al. (2017) Projections of temperature-related excess mortality under climate change scenarios. The Lancet Planetary Health. 7 – Franzke et al. (2020) Risk of extreme high fatalities due to weather and climate hazards and its connection to large-scale climate variability. Climatic Change. 8 – Haque et al. (2012) Reduced death rates from cyclones in Bangladesh: what more needs to be done? Bulletin of the World Health Organization 9 – Kaufman et al. (2020). A global database of Holocene paleoclimate records. Scientific Data. 10 – Burke et al. (2018) Pliocene and Eocene provide best analogs for near-future climates. PNAS. 11 – Schleussner et al. (2018). Crop productivity changes in 1.5 °C and 2 °C worlds under climate sensitivity uncertainty. Environmental Research Letters. 12 – Mbow et al. (2019) IP Food Security. In: Climate Change and Land: an IPCC special report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems. IPCC report. 13 – Rosenzweig et al. (2014). Assessing agricultural risks of climate change in the 21st century in a global gridded crop model intercomparison. PNAS. 14 – Moore et al. (2017) New science of climate change impacts on agriculture implies higher social cost of carbon. Nature. 15 – Piao et al. (2020). Characteristics, drivers and feedbacks of global greening. Nature Reviews Earth & Environment, 1(1), 14-27. 16 – Peñuelas et al. (2017) Shifting from a fertilization-dominated to a warming-dominated period. Nature Ecology & Evolution. 17 – Marcott et al. (2013) A Reconstruction of Regional and Global Temperature for the Past 11,300 Years. Science. 18 – Kaufman et al. (2020) Holocene global mean surface temperature, a multi-method reconstruction approach. Scientific Data. 19 – Degroot et al. (2020) Towards a rigorous understanding of societal responses to climate change. Nature. 20 – Fischer and Knutti (2015) Anthropogenic contribution to global occurrence of heavy-precipitation and high-temperature extremes. Nature Climate Change. 21 – Zhang et al. (2014) Nitrogen and phosphorous limitations significantly reduce future allowable CO2 emissions, Geophysical Research Letters. 22 – De Graaff et al. (2006) Interactions between plant growth and soil nutrient cycling under elevated CO2: a meta-analysis. Global Change Biology. 23 – Lesk et al. (2016) Influence of extreme weather disasters on global crop production. Nature. 24 – Ray et al. (2019) Climate change has likely already affected global food production. Plos One. 25 – National Academies of Sciences, Engineering, and Medicine (2016) Attribution of extreme weather events in the context of climate change. The National Academies Press. 26 – Zhu et al. (2016) Greening of the Earth and its drivers. Nature Climate Change. 27 – Friedlingstein et al. (2020) Global carbon budget 2020. Earth Syst. Sci. Data. 28 – Humphrey et al. (2018) Sensitivity of atmospheric CO2 growth rate to observed changes in terrestrial water storage. Nature. 29 – Yuan et al. (2019) Increased atmospheric vapor pressure deficit reduces global vegetation growth. Science Advances. 30 – Büntgen et al. (2021) Recent European drought extremes beyond Common Era background variability. Nature Geoscience. 31 – Overpeck and Udall (2020) Climate change and the aridification of North America. PNAS. 32 – Abram et al. (2021) Connections of climate change and variability to large and extreme forest fires in southeast Australia. Communications Earth & Environment. 33 – Perkins et al. (2012) Increasing frequency, intensity and duration of observed global heatwaves and warm spells. Geophysical Research Letters. 34 – Perkins-Kirkpatrick (2020) Increasing trends in regional heatwaves. Nature Communications. 35 – Andela et al. (2017) A human-driven decline in global burned area. Science.","Reviewers’ Overall Feedback: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. This op-ed contains so many statements that give readers the wrong impression about the impacts of CO2 and global warming. For example, CO2 levels and temperatures were markedly higher than today’s levels during the part of Earth’s history for which we have geologic proxy measurements. However, it’s also true that during most of that 500 million years, mammals did not even exist, let alone humans. During some of that ancient history, continents near the equator were too hot to support life, while tropical vegetation flourished at what is now the poles. It is fallacious to suggest that a near-instant return to these conditions would be anything less than catastrophic for humanity. This article from NOAA summarizes Earth’s CO2 and climate history for a non-technical audience, and this article provides more detail. Although much of Wrightstone’s op-ed consists of statements presented in a misleading context (like above), some of it is downright false. For example, Wrightstone states that our current global average temperatures are remarkable “only if your record is limited to the last 150 years or so.” That is not correct. The prevailing understanding in paleoclimatology is that our current global average temperatures are some of the highest since before the last Ice Age more than 12,000 years ago[9]. If current warming trends continued under the RCP8.5 emission scenario, then by mid-next century we would likely achieve temperatures not seen since the early Eocene, more than 50 million years ago (Burke et al., 2018, see Figure 1)[10]. As described in Burke et al. (2018), “Under the Representative Concentration Pathway 8.5 (RCP8.5) emission scenario, by 2030 CE, future climates most closely resemble Mid-Pliocene climates, and by 2150 CE, they most closely resemble Eocene climates. Under RCP4.5, climate stabilizes at Pliocene-like conditions by 2040 CE. Pliocene-like and Eocene-like climates emerge first in continental interiors and then expand outward.”[10] Figure 1—Temperature trends from the past 65 million years before present and potential geohistorical analogs of the future climate system. From Burke et al. (2018)[10]. Wrightstone confuses correlation with causation when he discusses the fact that over the past century, global agricultural productivity has increased and weather-related deaths have decreased. We cannot thank anthropogenic climate change for this. Rather, better infrastructure and better health care have reduced the number of people who die from environmental factors such as weather. Progress in crop science and technology (as well as unsustainable depletion of the biosphere) have enabled a steady upward trend in crop production, outweighing any marginal effects of CO2 and warming. Higher CO2 and temperature can aid crop yields in temperate regions, but it comes at the expense of yields in more vulnerable developing tropical regions. It is ethically indefensible that Wrightstone celebrates potential gains for agriculture in the global North while ignoring the numerous studies that describe damages in the global South. For example, Schleussner et al. (2018) conclude that “Even when accounting for the full effects of CO2 fertilisation in crop models, median local tropical yields for wheat and maize are still found to be negatively affected”[11]. They predict that the magnitude of this negative effect will double between 1.5C warming and 2C warming. The other logical fallacies in Wrightstone’s article are too numerous to list here. Without wanting to resort to ad hominem arguments, I find it difficult to believe that Wrightstone (who works in the fossil fuel industry in the extraction of shale oil and gas) is making these arguments in good faith. Rather, this appears to be an intentionally misleading article assembled by someone who, as a geoscientist, understands the technical details but who is using them to distract and confuse rather than to educate the public. Alexis Berg Research Associate, Harvard University: This article recycles old tropes such as “it’s been warm before”, “CO2 levels have been higher in the past” (millions of years ago!), “CO2 is plant food”, “warming is good for ecosystems/humans”, “so far impacts are small, so they will remain small”, etc. All these pseudo-arguments have been addressed many times before (see examples here, here, and here). This article is clearly motivated, misleading and biased. It presents some facts that are technically true – e.g., in the context of Earth’s geological history, we are in a cold, low-CO2 period (at least for now!) – but that are irrelevant to the issue of global warming: we care about changes from current conditions, to which human civilization is adapted. The article also contains factually erroneous claims (see annotations below). Katrin Meissner Professor, University of New South Wales: This article is an aggregation of false statements. It also includes a few partially right statements, but these are taken out of context and presented in a misleading way. It is written in a provocative and arrogant tone, the argumentation is based on lies. Each paragraph contains at least a misleading statement. Although high CO2 concentration is beneficial to some plant growth, the impact of climate change on the growth is mostly detrimental[12-14]. The increase in crop production is mostly linked to fertilizer and agriculture practices, not to the growth in CO2. In fact, there is evidence that climate change has already had detrimental consequences on food production[14], and this may get worse in the future[12]. Yes, there have been higher CO2 levels in the atmosphere, but this was way before humans appeared on our planet. The current CO2 levels, and the rate of change, are way above what the human race has experienced. CO2 in the atmosphere is there for a very long time (not each molecule individually but the concentration perturbation). This is what generates an “emergency”, because there is no going back. Annotations: The statements quoted below are from the video; comments are from the reviewers (and are lightly edited for clarity). “The science and data strongly support that our planet’s ecosystems are thriving and that humanity is benefiting from modestly increasing temperature and an increase in carbon dioxide.” ; “Earth’s ecosystems and inhabitants are thriving because of increasing CO2 and rising temperatures not in spite of them.” There is no science nor is there any data that globally support the assertion that ecosystems are thriving or that humanity would benefit from increasing temperature or increasing carbon dioxide. There are literally tens of thousands scientific publications that indicate that ecosystems are increasingly being degraded due to climate change and other impacts[1-4]. Many people have lost their lives during heat waves or climate change caused natural disasters[5,6]. Alexis Berg Research Associate, Harvard University: It’s true that vegetation has been increasing globally in the last 40 years (since we have satellite measurements). Models suggest CO2 fertilization is the main contributor to the growth of forests and natural ecosystems[15]. Warming has beneficial effects in high-latitude, temperature-limited regions (e.g., Arctic greening), but opposite in the Tropics. Direct human management (agriculture, afforestation) also plays a role in some regions[15]. However, further warming could start having more negative effects on global vegetation, while the beneficial impacts of CO2 could run into some limitations (e.g., nitrogen limitation)[16]. Note as well that current warming levels already have very noticeable negative impacts on marine ecosystems (i.e., coral reefs)[1-3]. “These facts refute the claim that Earth is spiraling into one man-made climate catastrophe after another.” There is no claim of any “spiraling”, there is just a very robust assessment that greenhouse gas concentrations are rising, that they cause rapid climate change, and that the societal consequences of these changes (economy, health, etc.) will be disastrous for a large part of the world’s human population in the near future[4-7]. “Concentrations of this gas are slightly less than 420 parts-per-million (ppm), or one-sixth the average historic levels of 2,600 ppm for the last 600 million years” To compare with the last 600 million year average is irrelevant. Levels are unprecedented with respect to the time that humans have lived on Earth. Katrin Meissner Professor, University of New South Wales: This statement is partially correct. The average historic level was not 2600 ppm, but there were periods of times when CO2 was very high, likely as high as 1500-2000ppm. The ecosystems and biogeochemistry were adapted to these conditions, and they looked very different from today. There were no humans, many of the mammals around us did not exist. Not to mention that the sun’s energy output was slightly smaller during that time. Changing the present day world into a “dinosaur world” within a century would not be good news for the ecosystems we depend on, or for us. Alexis Berg Research Associate, Harvard University: This is a silly point. Yes it was hotter, with more CO2, hundreds of millions of years ago, but humans – mammals! – weren’t there. We care about change now. 420ppm is unprecedented in the last million years at least. By the same token one could say that during the last 600 million years the Earth was mostly ice-free (no ice caps) – so we shouldn’t care if the ice caps melt now (i.e., 70 m of sea-level rise). “Increases in carbon dioxide in the last 150 years, largely from the burning of fossil fuels, have reversed a dangerous downward trend in the gas’ concentration. During the last glacial period, concentrations nearly reached the “line of death” at 150 parts per million, below which plants die. Viewed in the long-term geologic context, we are actually CO2 impoverished.” Katrin Meissner Professor, University of New South Wales: Plants have adapted to lower CO2 concentrations, for example with the appearance of C4 plants. Also, the CO2 concentrations have varied between similar minima during glacials and maxima during interglacials over the past 800,000 years. All the minima are well above 150 ppm. Alexis Berg Research Associate, Harvard University: The last part is not untrue, but irrelevant. Pre-industrial (around 1800) CO2 was 280ppm. For the last 10,000 years (human civilization) it has been around that value, increasing slightly – not decreasing – until modern emissions began. Even without current CO2 emissions and associated warming, there would be no threat of imminent ice age or very low CO2 conditions. “The first 250 years of that warming preceded 20th century CO2 increases and were necessarily 100% naturally driven.” The author makes the frequent mistake of mixing natural variability (the slight warming after the Little Ice Age) and current warming, which is due to greenhouse gas forcing[17]. These processes are well understood by climate scientists. In fact there is no alternative explanation for the recent rapid warming, as described in this Climate Feedback review. “Longer-term data reveal multiple warming periods since the end of the last major ice age 10,000 years ago, each warmer than today.” Alexis Berg Research Associate, Harvard University: Following the last ice age (20 thousand years) and deglaciation, current (Holocene) global CO2 and climate conditions were reached around 10 thousand years ago. Global temperatures kept slightly increasing until the Holocene maximum, around 7 thousand years ago, and then slowly decreased, until the abrupt warming of the last 150 years. The recent reconstruction by Kaufman et al. (2020) indicates that “The warmest 200-year-long interval took place around 6500 years ago when global temperature was 0.7 °C (0.3, 1.8) warmer than the 19th Century (median, 5th, 95th percentiles).” Whether or not we are already there, the fact is that modern warming is going to lead to global climate conditions several times warmer than that (e.g., if we get to +3 or 4°C of global warming). Figure 1—Global mean temperature of the last 12,000 years using different methods to reconstruct past global mean surface temperature (colored lines). The black line indicates instrumental data from 1900-2010. From Kaufman et al (2020)[18]. “There is a strong correlation between the rise and fall of temperature and the ebb and flow of civilizations. During the last three warm periods dating back 6,000 years to the advent of the first great civilizations, humanity prospered and great empires arose. Intervening cold periods brought crop failure, famine, and mass depopulation. History advises us to welcome warmth and fear cold.” Katrin Kleemann Visiting Scholar, Ludwig Maximilian University of Munich: The examples mentioned here are vague, it is unclear which cold periods or which incidents of crop failure, famine, or population loss the author refers to. It is also unclear which “civilizations” the author is referring to. While it is true that past societies experienced natural climate change, these were regional and smaller in magnitude than present-day global warming. Nevertheless, the climate change during periods, such as the Late Antique Little Ice Age or the Little Ice Age, was profound enough to alter human life. It is, of course, deterministic to argue that the climate was the only factor that brought about crop failure, famine, or population loss. In reality, several factors come together that can then lead to crop failure or famine: for instance, inadequate planning, social upheaval, economic struggles, conflicts with other groups, etc.[19]. Past scholarship has focused a lot on the collapse of societies; however, recent scholarship has discovered that past societies and communities often were resilient in the face of modest climate change. Despite the climatic change, these societies or communities maintained their structure, function, and identity. Some societies adapted to the new, often colder, climatic regime and even managed to exploit the opportunities created by the shift in environmental circumstances[19]. The climate change faced by societies during the Late Antique Little Ice Age or the Little Ice Age was modest compared to the much greater magnitude of climate change that we are facing in the present and future due to the warming that our greenhouse gas emissions are causing. In the present, we are already experiencing what it looks like to live in a warming world – heat waves, rising temperatures on land and in the oceans, wildfires, to mention but a few, have devastating consequences for millions of people around the planet[19]. There is no such “strong correlation”. The rise and fall of social systems is affected by many factors and climate may be one of them. In most cases, there is insufficient evidence to explain the fall of past societies with a single factor. More importantly, none of the past “civilizations” had similarly large global populations and similarly high dependence on stable environmental conditions. Heat waves are becoming more frequent and more severe in many parts of the world. They even occur in the ocean and are one of the key drivers for the loss of tropical coral reefs. “Modestly warming temperature and increasing carbon dioxide lead to longer growing seasons and more productive harvests. The world’s remarkable ability to increase food production year after year is attributable to mechanization, agricultural innovation, CO2 fertilization, and warmer weather. Crop and food production has seen only positive effects from relatively small changes in the global climate.” Katrin Meissner Professor, University of New South Wales: Plants cannot live on CO2 alone. Those plants that profit from higher CO2 will need more water to maintain their larger growth and to compensate for larger evaporators-transpiration due to increased heat. They will therefore be more vulnerable to changes in precipitation patterns, and to aridification, which will be one of the consequences of higher CO2 levels in many regions[20]. They will also need more nutrients, which are not necessarily available[21,22]. Other plants do not profit from higher CO2, and their photosynthesis rates have been shown to decrease under higher CO2. More importantly, higher CO2 has been shown to reduce the nutritional quality of some plants we depend on, such as wheat[14]. Modestly warming temperature indeed leads to longer growing seasons and modest warming and increasing carbon dioxide can lead to more productive harvests (depending on the local conditions). However, with global warming, heatwaves and droughts are increasing in frequency and intensity[20]. Increases in extreme weather events can have strong negative effects on crop productivity and are expected to negatively impact food production[23]. Crop and food production as well as human settlements are also threatened by the increasing risk of wildfires due to global warming. Alexis Berg Research Associate, Harvard University: It is complicated to separate all factors contributing to crop yield changes, but there is evidence suggesting that global warming is already negatively impacting global food production, at least in some regions[24]. Note that crop yields respond not only to mean climate, but also to extreme events (e.g., heat waves, droughts) that get more intense and/or frequent with warming[23]. Of course, further warming makes it only more likely that negative impacts will start occurring. “Contrary to sensational media reports, extreme weather-related deaths in the U.S. have decreased more than 98% over the last 100 years. Twenty times as many people die from cold as from heat, according to a worldwide review of 74 million temperature-related deaths by Dr. Antonio Gasparrini and a team of physicians. Global warming saves lives.” Antonio Gasparrini Senior Lecturer, London School of Hygiene and Tropical Medicine: I think Mr. Wrightstone refers to an article I published some time ago, where we showed that indeed cold is currently associated with a much higher mortality[5]. However, this does not mean that the decrease in cold-related deaths expected with the warming of the planet will offset the heat-related increase in the future. Actually, from the evidence we have gathered so far by a follow-up study on an even larger dataset , it seems that this is not true unless in mild warming scenarios that require strict mitigation strategies[6]. Katrin Meissner Professor, University of New South Wales: This statement is false, based on fatality data from NOAA. Alexis Berg Research Associate, Harvard University: Moot point. The concern about global warming doesn’t stem from the direct impact of atmospheric conditions on human lives or deaths, but rather from its impact on the environmental factors that support society – water resources, natural and cultivated ecosystems, ecosystem services, etc. Note, however, that an increase in humid heat could lead to literally lethal atmospheric conditions during heatwaves in parts of the Tropics under a high-warming scenario. “During this period of increasing CO2 and slight warming, we have seen increasing food production, soil moisture, crop growth, and a “greening” of the Earth. All the while droughts, forest fires, heat waves, and temperature-related deaths have declined substantially.” Unfortunately, droughts, forest fires and heat waves are increasing world-wide, and so do temperature-related deaths[6,25]. The statements made here are invented by the author and entirely “at odds with reality”. The earth has indeed been greening in the past decades, and this has been attributed primarily to the increasing CO2 concentrations[26]. Terrestrial ecosystems have sequestered about 30% of anthropogenic CO2 emissions, and this land sink has retarded climate change[27]. However, as global warming progresses, negative impacts of especially heat and drought are increasing. In fact, we are already seeing the first signs of a decline in the land CO2 sink and increasing extreme heatwaves and droughts seem to be the most important reason[16,28,29]. Katrin Meissner Professor, University of New South Wales: Droughts and aridification have increased in many regions of the world. For example in Europe and North America[30,31]. Forest fires have increased and now show the fingerprint of global warming, e.g. in Australia[32] and the Arctic. Heat waves have increased in frequency, intensity and duration[33]. Alexis Berg Research Associate, Harvard University: I am not aware of any study showing an increase in soil moisture over the last decades (soil moisture is exceedingly difficult to measure globally). Heat waves have demonstrably increased[34]. Global burnt area has decreased globally over the last 20 years, yes (by 25%), but that signal is dominated by agricultural intensification and expansion, which replaces naturally-burning grasslands and savannah, in particular in the Tropics[35]. Some regions clearly show warming-influenced growth in wildfires in natural ecosystems (e.g., Western US, high latitudes). Changes in drought frequency/intensity are complex and hard to estimate – warming may not cause more droughts but may make existing ones worse. But in any case, the consensus is certainly not that there has been any “substantial decline” in droughts in recent decades. “Yes, there has been some warming, but it has been minuscule compared to the temperature change all of us experience in the course of a day.” Katrin Meissner Professor, University of New South Wales: The overall global warming that has been observed so far is small compared to the diurnal temperature difference we experience every day. But this is also a meaningless statement. We could take our daily food intake as an example. Most of the minutes of the day we eat nothing. During dinner, we might eat a pizza and drink a beer and therefore absorb 2000 calories within 20 minutes. Our intake throughout the day varies between 0 and 1000 calories per 10 minutes, assuming that our breakfast and lunch is a bit less calorific. Compared to a range between 0 and 1000, 10 calories is nothing – I therefore suggest we should all constantly eat 10 calories every 10 minutes throughout the day, on top of our normal intake, and let’s see what this will do to our health. UPDATES: 9 June 2021: Two of Amber Kerr’s statements were updated to explain that current global average temperatures are some of the highest since before the last Ice Age and to clarify the results discussed from Burke et al. (2018)[10]."
https://science.feedback.org/review/wall-street-journal-article-repeats-multiple-incorrect-and-misleading-claims-made-in-steven-koonins-new-book-unsettled-steven-koonin/,-1.7,"The Wall Street Journal, by Mark P. Mills, on 2021-04-25.",,"""‘Unsettled’ Review: The ‘Consensus’ On Climate""",,,,"1 – Kjeldsen et al. (2015) Spatial and temporal distribution of mass loss from the Greenland Ice Sheet since AD 1900. Nature. 2 – Frederikse et al. (2018) A Consistent Sea-Level Reconstruction and Its Budget on Basin and Global Scales over 1958–2014. Journal of Climate. 3 – Frederikse et al. (2020) The causes of sea-level rise since 1900. Nature. 4 – Dangendorf et al. (2019) Persistent acceleration in global sea-level rise since the 1960s. Nature Climate Change. 5 – Horton et al. (2018) Mapping Sea-Level Change in Time, Space, and Probability. Annual Review of Environment and Resources. 6 – IPCC (2014) Climate Change 2014: Summary: for Policymakers. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. 7 – Ortiz-Bobea, et al. (2021) Anthropogenic climate change has slowed global agricultural productivity growth. Nature Climate Change. 8 – Doerr and Santín (2016) Global trends in wildfire and its impacts: perceptions versus realities in a changing world. Philosophical Transactions of the Royal Society B. 9 – Bowman et al. (2020) Vegetation fires in the Anthropocene. Nature Reviews Earth & Environment. 10 – Gonzalez et al. (2018) Chapter 25: Southwest. In Impacts, Risks, and Adaptation in the United States: Fourth National Climate Assessment, Volume II. 11 – Hausfather et al. (2020). Evaluating the performance of past climate model projections. Geophysical Research Letters. 12 – Mouginot and Rignot (2019). Forty-six years of Greenland Ice Sheet mass balance from 1972 to 2018. PNAS. 13 – Church and White (2011) Sea-Level Rise from the Late 19th to the Early 21st Century. Surveys in Geophysics. 14 – Jevrejeva et al.(2014) Trends and acceleration in global and regional sea levels since 1807. Global and Planetary Change. 15 – Ray and Douglas (2011) Experiments in reconstructing twentieth-century sea levels. Progress in Oceanography. 16 – Hay et al. (2015) Probabilistic reanalysis of twentieth-century sea-level rise. Nature. 17 – Dangendorf et al. (2019), Persistent acceleration in global sea-level rise since the 1960s. Nature Climate Change. 18 – Blunden and Arndt (2019). State of the Climate in 2018. Bulletin of the American Meteorology Society. 19 – Nerem et al. (2018) Climate-change–driven accelerated sea-level rise detected in the altimeter era. PNAS. 20 – Kopp et al. (2016) Temperature-driven global sea-level variability in the Common Era. PNAS. 21 – Walker et al. (2021) Common Era sea-level budgets along the U.S. Atlantic coast. Nature. 22 – Bamber et al. (2019) Ice sheet contributions to future sea-level rise from structured expert judgment. PNAS. 23 – Yang et al. (2014) Spatial and temporal patterns of global burned area in response to anthropogenic and environmental factors: Reconstructing global fire history for the 20th and early 21st centuries. Journal of Geophysical Research: Biogeosciences. 24 – Williams et al. (2019) Observed Impacts of Anthropogenic Climate Change on Wildfire in California. Earth’s Future. 25 – Abatzoglou and Williams (2016) Impact of anthropogenic climate change on wildfire across western US forests. PNAS. 26 – Goss et al. (2020) Climate change is increasing the likelihood of extreme autumn wildfire conditions across California. Environmental Research Letters. 27 – Abram et al. (2021) Connections of climate change and variability to large and extreme forest fires in southeast Australia. Communications Earth & Environment. 28 – Feurdean et al. (2020) Recent fire regime in the southern boreal forests of western Siberia is unprecedented in the last five millennia. Quaternary Science Reviews. 29 – Jones et al. (2020) Climate Change Increases the Risk of Wildfires. ScienceBrief Review. 30 – Gensini and Brooks (2018) Spatial trends in United States tornado frequency. npj Climate and Atmospheric Science. 31 – Elsner et al. (2018) Increasingly Powerful Tornadoes in the United States. Geophysical Research Letters. 32 – Diffenbaugh et al. (2013) Robust increases in severe thunderstorm environments in response to greenhouse forcing. PNAS. 33 – Hoogewind et al. (2017) The Impact of Climate Change on Hazardous Convective Weather in the United States: Insight from High-Resolution Dynamical Downscaling. Journal of Climate. 34- Brooks et al. (2014) Increased variability of tornado occurrence in the United States, Science. 35 – Marvel et al. (2019) Twentieth-century hydroclimate changes consistent with human influence. Nature. 36– Diffenbaugh et al. (2015) Anthropogenic warming has increased drought risk in California. PNAS. 37 – Williams et al. (2020) Large contribution from anthropogenic warming to an emerging North American megadrought. Science. 38 – Kossin et al. (2020) Global Increase in Major Tropical Cyclone Exceedance Probability over the Past Four Decades. Proceedings of the National Academy of Sciences. 39 – Liu et al. (2019) Causes of large projected increases in hurricane precipitation rates with global warming. npj Climate and Atmospheric Science. 40 – Knutson et al. (2020)Tropical Cyclones and Climate Change Assessment: Part II: Projected Response to Anthropogenic Warming. Bulletin of the American Meteorological Society. 41 – Hsiang et al. (2017) Estimating economic damage from climate change in the United States. Science. 42 – Lüthi et al. (2008). High-resolution carbon dioxide concentration record 650,000–800,000 years before present. Nature. 43 – Foster et al. (2017). Future climate forcing potentially without precedent in the last 420 million years. Nature Communications. 44 – Mills et al. (2019) Modelling the long-term carbon cycle, atmospheric CO2, and Earth surface temperature from late Neoproterozoic to present day. Gondwana Research. 45 – Siegert et al. (2020) What ancient climates tell us about high carbon dioxide concentrations in Earth’s atmosphere. Grantham Institute Briefing Note 13, Imperial College London.","Reviewers’ Overall Feedback: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: The Wall Street Journal article reviewing Dr. Steven Koonin’s new book is a mix of factually correct, correct but misleading, and inaccurate statements. It seems to be cherry-picking different datasets and factoids to downplay the severity of future climate impacts. For example, while Koonin mentions that global area burned by fires is decreasing, he is conflating purposefully set agricultural fires (which are decreasing) with wildfires that are increasing in many regions due to climate change. Similarly, he highlights one dataset that suggests some ambiguity about whether the rate of sea level rise today exceeds that of the 1940s, while ignoring four other datasets that show clear modern acceleration (see below). Finally, his criticism that climate models have poor skill in “retroactive prediction” ignores the fact that climate models published since the 1970s were quite accurate in projecting the warming that actually occurred in the years after they were published, as we discuss in our recent paper[11]. This book review uncritically regurgitates an assortment of misleading and/or outright false claims that presumably appear in the underlying volume. As has been thoroughly emphasized by scientists here and elsewhere, climate change is clearly increasing the frequency and/or severity of different kinds of extreme weather events in the United States and elsewhere (including heat waves), has indeed resulted in an accelerating rate of sea level rise, and has very large societal and economic implications. Twila Moon Research Scientist, University of Colorado, Boulder: Many conclusions highlighted in this article are examples of cherry-picking information and failing to provide the context of change. In other instances, statements are fully wrong and unsupported by scientific research. Kerry Emanuel Professor of Atmospheric Science, MIT: Early in the review, the novelist Michael Chrichton is quoted as saying “If it’s consensus, it isn’t science. If it’s science, it isn’t consensus. Period.” But those making policy would be foolish not to go with a scientific consensus; anything else would almost by definition be subjective. What is the point of quoting Chrichton if not to cast doubt on the value of scientific consensus? The existence of a consensus is not at all tantamount to the idea that the “science is settled”. Annotations: The statements quoted below are from the article; comments are from the reviewers (and are lightly edited for clarity). ”Greenland’s ice sheet isn’t shrinking any more rapidly today than it was eighty years ago.” Twila Moon Research Scientist, University of Colorado, Boulder: This statement is untrue. The per year average ice loss during 2003-2010 is roughly 2.5 times higher than during 1900-2003. This is evident in the following figure from Kjeldsen et al.[1] Figure 3 — Surface elevation change rates in Greenland during 1900-1983 (a), 1983-2003 (b), and 2003-2010 (c). The numbers listed below each panel are the integrated Greenland-wide mass balance estimates expressed as gigatonnes per year and as millimetre per year GMSL (global mean sea level) equivalents. From Kjeldsen et al. 2015[1]. If we look in more detail at changes over 1972-2018, we can further see that the ice sheet was mostly in balance (gain about the same amount of snow/ice in winter as is lost in summer) during the 1970s and 1980s[12]. It was only in the mid-1990s that Greenland ice loss began to increase more substantially. Over the last 20 years, ice loss has been rapid and large, creating measurable sea level rise, which we experience as increases in coastal erosion, flooding, problems with water and sewer systems at the coasts, and saltwater inundation of freshwater sources. ”The rate of sea-level rise has not accelerated.” Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: This statement is inaccurate; all observational sea level rise (SLR) datasets show rapid acceleration in recent years, and most now show sea levels rising faster than at any point since records began in the early 1900s. Reconstructing past changes in global sea levels is far from a simple task. While high-quality satellite measurements with global coverage have been available since the early 1990s, prior to that researchers had to rely on tide gauges scattered around the world. These tide gauges primarily cover coastal regions, leaving it up to researchers to figure out how best to fill the gaps. Tide gauges are also subject to factors that can complicate the interpretation of local sea level changes, namely subsidence (sinking land) or isostatic rebound (rising land due to melting glaciers). The IPCC 5th Assessment Report featured three estimates of global sea level rise[6]: from Church and White[13], Jevrejeva[14], and Ray and Douglas[15]. Two additional SLR datasets – Hay et al.[16] and Dangendorf et al.[17] – have been published in recent years. All five of these datasets are shown in the figure 5 below (coloured lines), along with satellite altimeter measurements (in black) after 1993. Figure 4— Estimates of global mean sea level from 1992-2006 (in millimetres), and 20-year average rate of global sea level rise (mm/year) from various references. From Carbon Brief. Recently, there has been some debate around whether the current rate of SLR exceeds that experienced back in the 1940s. Three of the five datasets (Dangendorf, Hay, and Church and White) suggest that the current rate of sea level rise – as measured by accurate satellite altimeters – is around 50% faster than was experienced in the 1940s. The Ray and Douglas dataset suggests that current rates of SLR measured by satellite altimeters are modestly above the 1940s peak, while one of the five – Jevrejeva – suggests that the current rate of SLR is below that of the 1940s. However, even the authors of the Jevrejeva dataset suggest in their accompanying paper that a longer view of sea level – from 1800 to present – still suggests that “the rate of sea level rise is increasing with time”[14]. There is also evidence of accelerating SLR over the post-1993 period when high-quality satellite altimetry data is available. According to the 2018 State of the Climate report[18], acceleration in SLR during the post-1993 period is around 0.1mm each year; this means that the rate of SLR is increasing by 1mm per year each decade. For more details, see my discussion of sea level rise acceleration at Carbon Brief. Thomas Frederikse Postdoctoral researcher, Jet Propulsion Laboratory/California Institute of Technology: Satellite measurements, which started in 1993, show a clear acceleration in sea level [19]. Also, if we go further back in time, tide-gauge observations show that sea levels are persistently accelerating since the 1960s[4], and overall, the observed sea-level rise during the 20th century is higher than during any other century over the last 3000 years[20,21]. [Comment from a previous evaluation of a similar claim] This is literally the opposite of what a growing body of recent evidence has shown. Research actually shows that rates of global sea level rise have accelerated in recent years[19], and estimates regarding the upper end of plausible further sea level rise over the coming century have actually increased considerably as the non-linear contribution by continental ice sheets comes into clearer focus[22]. So, if anything, sea level rise is becoming more of a problem than previously thought. ”The extent of global fires has been trending significantly downward.” Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: This statement is accurate but misleading. The vast majority of fires globally are purposefully set for agricultural clearing, and these have declined in recent years. Conflating all fires with forest and wildfires is not helpful in understanding changing drivers of fire risk. A 2014 study suggests that in the tropics climate change may have also reduced the area burned over the past 50 years, due, in part, to wetter conditions[23]. However, they find that climate change has likely increased fire risk in the high latitudes and mid-latitudes over recent decades. Figure 5 —Contribution of different factors in changes since 1900 in forest-fire area globally (a) and for different regions : (b) northern high latitudes (>55°N), (c) northern extratropics (55°N to 30°N), (d) tropics (30°N to 20°S), and (e) southern extratropics (>20°S). Effects of climate change (including changes in temperatures and precipitation) are shown by the vertical stripes. Human land management activity is shown by the diagonal stripes, while the effect of CO2 fertilization and nitrogen deposition is shown by the dots. From Yang et al. (2014)[23]. Hotter and drier conditions have been a major factor in the increase in areas burned by wildfires in many regions – such as the western US – in recent years. For example Williams et al. (2019) found that in California, “nearly all of the increase in summer forest‐fire area during 1972–2018 was driven by increased VPD [vapor pressure deficit]” driven by climate change[24]. Earlier work by Abatzoglou and Williams (2016) found that fuel aridity – driven by observed warming and drying – was the major driver of enhanced fire activity in the Western US[25]. For more details, see my Carbon Brief analysis of the role of climate change in US wildfires. [Comment from a previous evaluation of a similar claim] Overall trends in area burned globally are strongly driven by decreases in intentional agricultural burning in tropical areas, which is not related to climate change. In regions where non-agricultural fires occur naturally (including the western United States[24-26], eastern Australia[27], and the Siberian Arctic[28], there is strong evidence that climate change has already increased the severity and extent of wildfire[29]. [Comment from a previous evaluation of a similar claim] The observed decline in global average area burned has been misused numerous times to support false claims about the role of climate change in wildfire trends. Climate change as well as human activities affect global fire activity (see here for a summary and update on Doerr and Santin, 2016[8]). The overall global decrease is mostly driven by less fire in what used to be more extensive savannahs and grasslands and is largely due to the human driven removal of flammable vegetation. In quantitative terms, fire in those grassy ecosystems account for around 70% of the total global area burnt, so the reduction in fire activity here outweighs the increase in burned area that we are seeing in other parts of the world over the last two decades where fires have greater impacts such as Canada, parts of the USA or Siberia. In other words, where humans have not converted flammable landscapes to less or-non flammable landscapes by removing or changing the vegetation, warming temperatures are, overall, associated with an increase in fire activity. A very thorough global analysis of trends and fire knowledge overall has been made by Bowman et al. in 2020[9]. Gary Yohe Professor of Economics and Environmental Studies, Wesleyan University: Fires are local events whose regional patterns of intensity and frequency fit well into risk-based calibrations. They can also be perfect examples of a new troubling tendency in which several types of impacts attributed to climate change show up at the same place at the same time, feeding on each other combining forces to produce still greater extremes – something that long-term trends of one type of climate change impact simply cannot explain. Take, for example, the 2020 California fire experience. Only three of the state’s largest 20 fires (in terms of acres burned) had burned prior to 2000, but nine of the biggest 10 have occurred since 2012. That is, moving toward the next decade, extreme fires were becoming more likely and more intense. In 2017, 9,270 fires burned a record 1.5 million acres. The Mendocino Complex fire the next year became the “largest wildfire in California history.” And then came 2020. A new largest fire in California history, the Complex fire, started in August of 2020. Soon after came the 3rd, 4th, 5th, and 6th largest in history. By October 3, these five conflagrations had combined with nearly 8,000 other more “ordinary” fires to kill 31 people and burn more than four-million acres; and, on that day, all five were still burning at the same time. Why is this happening? It is becoming clear that nature can produce combinations of influences on local environmental conditions. Many of the 2020 fires in California were caused by literally thousands of dry lightning strikes that fed into a witches’ brew of simultaneous conditions that have all been linked to global warming: the end of a multi-year record drought all-time record heat punctuated July, August, and much of September widespread tinderbox stands of dead trees from multi-year and growing infestations of bark beetles decades of normal warming that had extended the western fire season by some 75 days ”tornado frequency and severity are also not trending up; nor are the number and severity of droughts.” Kerry Emanuel Professor of Atmospheric Science, MIT: Koonin sets up a strawman in claiming that tornado frequency and severity are not trending up. The scientific consensus on this is that we simply do not have the data to determine trends in tornadoes, and what little theoretical work has been done on this suggests that severity might go up and frequency might go down, but again there is no real consensus. [Comment from a previous evaluation of a similar claim] There is relatively little evidence in either direction at this point in time regarding global or even regional trends in tornado frequency/intensity. This is largely due to sparse and temporally inhomogeneous historical records in the United States, and virtually non-existent records in other regions. There is some evidence of regional shifts in tornado frequency[30], and perhaps an increase in overall tornado “power” in the United States[31], but in general there is an absence of strong evidence regarding this claim. Future projections regarding climate change and tornado risk are of somewhat low confidence, but there is evidence that atmospheric environments favorable for severe convective storms (which are the types of storms capable of producing tornadoes) may increase in the future due to climate warming[32,33]. Andreas Prein Project Scientist, National Center for Atmospheric Research: [Comment from a previous evaluation of a similar claim] It is not clear if climate change will make U.S. tornadoes worse or more frequent. The observational record does not show any significant change in the frequency of U.S. tornadoes in the last 60 years but there is a tendency that more tornadoes occur during big outbreak days[34] and there are spatial shifts in the occurrence of tornadoes[30]. Whether these changes are related to climate change is, however, unclear. ” the number and severity of droughts are also not trending up.” [Comment from a previous evaluation of a similar claim] Observed spatial trends in global hydroclimate over the past century have been consistent with those expected from human influence in the climate system[35]. In many mid-latitude and subtropical regions, this has indeed included an increase in the frequency/intensity of drought[36,37]–but in other regions (such as the Northern Hemisphere high latitudes), this includes an increase in moisture availability and decrease in drought (as expected from climate model simulations). Therefore, it doesn’t really make sense to make blanket statements regarding overall global drought trends, since only some places are expected to get drier (and others wetter) in a warming climate.“Humans have had no detectable impact on hurricanes over the past century” Kerry Emanuel Professor of Atmospheric Science, MIT: This statement is flat out wrong. In the first place, the theoretically predicted trends would not have been detectable in the sparse and noisy hurricane record until recently, and in fact they HAVE recently been detected. The most up-to-date research published in the Proceedings of the National Academy of Sciences demonstrates an increase in the proportion of hurricanes that become major hurricanes (Category 3-5) globally, supporting theoretical predictions that date back to 1987 (see figure below)[38]. Figure 6—The proportion of major hurricane intensities to all hurricane intensities globally from 1979-2017. Data is binned into 3-year periods. The proportion of global major hurricanes increased by 25% over the 39-year time period analyzed. From Kossin et al. (2020)[38]. Furthermore, the phrase “in the past century” is telling nothing since no one familiar with the global record of tropical cyclones would look at data prior to 1980; it is just way too poor to be able to detect trends. [Comment from a previous evaluation of a similar claim] While there remains no strong evidence for an increase in tropical cyclone (hurricane) frequency on a global basis, there is evidence that the most intense tropical cyclones are indeed becoming stronger in terms of maximum wind speeds and minimum central pressure[38] and are producing more extreme rainfall[39]. In fact, these trends are consistent with predictions regarding tropical cyclone behavior due to global warming: there is a strong expectation that the maximum potential intensity of hurricanes will increase due to rising ocean temperatures, even as the overall frequency of such storms does not change greatly or perhaps even decreases[40]. ”Global crop yields are rising, not falling.” Frances Moore Assistant Professor, University of California Davis: While global crop yields are rising, this does not constitute evidence that climate change is not adversely affecting agriculture. IPCC estimates are that increased heat and drought resulting from anthropogenic warming will slow the rate of yield growth, not reverse it[6]. Given a growing population and rising incomes, this will place increasing strain on the global food supply. A recent paper by Ortiz-Bobea et al. (2021) found that anthropogenic warming since 1961 removed the equivalent of 7 years of productivity growth[7]. The effect is substantially more severe in warmer regions such as Africa and Latin America and the Caribbean. Moreover, the authors concluded that “Global agriculture has grown more vulnerable to ongoing climate change”. David Lobell Associate Professor, Stanford University: This statement implies that people are claiming global crop yields are falling, which is false. it also is a logical fallacy to say that if things aren’t causing a net decrease then it isn’t a concern. One could say the economy is larger than it was 30 years ago, so nothing hurting the economy is a concern. Or global health is better, so a pandemic is no big deal. ”The net economic impact of human-induced climate change will be minimal through at least the end of this century.” Gary Yohe Professor of Economics and Environmental Studies, Wesleyan University: It is impossible to support a statement like this because economic damages are very dependent on unpredictable investments in adaptation and because sectoral coverage of the aggregate economy is woefully incomplete. A much more honest statement should read something like this from the IPCC Fifth Assessment: “there is low to medium confidence in attribution of climate change influence on a few sectors… Risks of global aggregate impacts are moderate for additional warming between 1°C to 2°C compared to 1986–2005… Aggregate economic damages accelerate with increasing temperature (limited evidence, high agreement) but few quantitative estimates have been completed for additional warming around 3°C.” Since 2014, more comprehensive studies have offered still incomplete portraits of the correlations between distributions of net economic damage (not just fitted values) along alternative global development pathways and increases in global mean temperature[41]. See figure below : Figure 7 — Estimates of total direct damages across all sectors from climate change on the U.S. economy. The x-axis refers to temperature change (°C) for 2080-2099 relative to 1980-2010. From Hsiang et al. 2017[41]. ”while global atmospheric CO2 levels are obviously higher now than two centuries ago, they’re not at any record planetary high—they’re at a low that has only been seen once before in the past 500 million years.” Scott Wing Curator and Research Scientist, Department of Paleobiology, Smithsonian Institution: This statement is incorrect. CO2 levels were lower than today’s at every glacial maximum for the last 800,000 years[42], as revealed by ice core records (see Figure 8 below). Figure 8 — Past CO2 concentration obtained from air trapped in ice cores from Antarctica. From https://keelingcurve.ucsd.edu For times before ice cores (>800,000 years) CO2 levels have to be inferred less directly from geochemical or biological proxies. These proxies have larger uncertainties associated with them than direct measurements or ice cores. Still, today’s levels are thought to be similar to those for the Pliocene and late Miocene, 2-10 million years ago. Of course polar ice caps were much smaller and sea levels much higher when CO2 was as high as it is now. Going farther back atmospheric CO2 concentrations becomes less certain, but probably it was higher than present during much of the long warm period prior to Antarctic glaciation beginning 34 million years ago and going back to the last major ice age in the Carboniferous, about 300 million years ago[43]. Lee Kump Professor, PennState University: This statement is misleading. Yes, atmospheric CO2 levels have been much higher than they are now in the VERY DISTANT geological past. But 500 million years ago the sun was dimmer than today, and high CO2 levels compensated for low irradiance. As the sun has become brighter over the history of our planet, CO2 levels in general have fallen, keeping our planet habitable[44]. So statements like “record planetary high” are meaningless. What’s meaningful is that at over 400 parts per million, the atmosphere today has a carbon dioxide level that Earth hasn’t seen in the last 2-5 million years, and climates at that time were warmer than today, ice sheets were smaller, and sea level was higher. Various scenarios for fossil-fuel burning take us above 1000 ppm in the next several decades, a level not seen for over 50 million years and at a time without ANY significant ice sheets on the planet and a much warmer climate (at least 10°F warmer on a global average). Figure 9— Estimates for atmospheric CO2 concentration (colored lines) during the last 420 millions years, based on different proxies. Average error shown as light grey bands. From Mills et al.[44] Dana Royer Professor, Wesleyan University: The fact that CO2 levels have been higher in the past[45] should not be used as evidence that humans are not changing the climate or that we should not be concerned about our near future. Statements like the one above are common for climate skeptics, but they widely miss the mark for two main reasons: If we continue on our current trajectory, global temperatures will soon reach levels not experienced since the time when ice sheets (like on Antarctica and Greenland) were absent. This was a “very” different Earth, and one humans have no experience living in. The “rate” of climate change is faster than all documented climate change events in the geologic record. The fastest rates of change that we know about (in thousands of years) are associated with mass extinctions. Our current rate of change is hundreds of years. This is scary and does not bode well.CORRECTION (2 JUNE 2021) This review was updated in order to correct an error made in interpreting the Greenland Ice Sheet mass balance figure from Kjeldsen et al[1]. The Greenland Ice Sheet didn’t lose more mass during 2003-2010 than during all of 1900-2003 combined as previously written. Rather, the figure shows that the per year average ice loss during 2003-2010 is roughly 2.5 times higher than during 1900-2003."
https://science.feedback.org/review/bidens-climate-plan-doesnt-say-anything-about-limiting-meat-consumption-contrary-to-daily-mail-fox-news-claim/,Inaccurate,"Daily Mail, Emily Crane, 2021-04-22",Biden’s climate plan limits meat consumption by 90%; “Biden's climate plan could limit you to eat just one burger a MONTH” ,,Inaccurate: President Joe Biden’s climate plan to reduce greenhouse gas emissions in half by 2030 doesn’t include any statements about limiting meat consumption.,"In April 2020, President Joe Biden announced a climate plan to halve greenhouse gas emissions in the US by 2030. The plan doesn’t include any statements about limiting red meat consumption. The climate plan primarily focuses on investing in carbon pollution-free energy sources, reducing carbon pollution in transportation, and enhancing carbon sinks, such as forests and agricultural soils. ",Biden’s climate plan limits meat consumption by 90%; “Biden's climate plan could limit you to eat just one burger a MONTH” ,,"Review: The claim that President Joe Biden’s climate plan could limit meat consumption appeared in an article published by the Daily Mail in April 2021 and was repeated in numerous Twitter and Facebook posts. A version of this claim also appeared on Fox News, but the outlet recently apologized for airing misinformation. These claims received hundreds of thousands of interactions on Facebook and other social networks. Although few specifics have been announced, Biden’s climate plan aims to cut US greenhouse gas emissions in half by 2030. The plan doesn’t include any statements about limiting meat consumption, contrary to implications made in the Daily Mail article. For example, the article includes a graphic stating “What will be required to meet Joe’s green targets: cut 90% of red meat out diet, only eat 4lbs a year”. However, the speculative claims made in the Daily Mail article aren’t based on Biden’s climate plan, but rather on an unrelated 2020 study from the University of Michigan on meat consumption. As stated in a 22 April 2021 White House Fact Sheet, the climate plan aims to reduce greenhouse gas emissions in half by 2030 through investments in carbon pollution-free energy sources, reducing carbon pollution in transportation, and investing in carbon sinks, such as forests and agricultural soils. The plan also aims to cut emissions and reduce costs for families by upgrading the efficiency and electrification of buildings through heat pumps, induction stoves, and following modern energy codes. According to an AP fact-check, “Martin Heller, one of the authors of the University of Michigan study, confirmed in an email to The Associated Press that there was no connection between the research and Biden’s climate plan”. On April 26, 2020, the United States Department of Agriculture spokesperson said that there is no truth to the claim that Biden’s climate plan limits red meat consumption, in an article published by The Hill. “This is a fabrication. There is no such effort or policy that exists by this Administration. It’s not a part of the climate plan nor the emissions targets. It is not real” As reported in a Politico article, Agriculture Secretary Tom Vilsack stated during a virtual briefing hosted by the North American Agricultural Journalists, “There is no effort designed to limit people’s intake of beef coming out of President Biden’s White House or USDA”. UPDATE 30 April 2021: This post was updated to state that the Daily Mail article claimed that Biden’s climate plan could limit meat consumption."
https://science.feedback.org/review/video-promoted-by-john-stossel-for-earth-day-relies-on-incorrect-and-misleading-claims-about-climate-change/,-1.8,"Stossel TV, by David Legates, Patrick Michaels, John Stossel, on 2021-04-17.",,"""Are we doomed?""",,,,,"Reviewers’ Overall Feedback: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Andrew King Research fellow, University of Melbourne: This video is misleading in so many ways it’s hard to know where to begin. For a start there’s a repeated assertion that climate “alarmists” won’t enter debate on climate change, but there are many examples of renowned climate scientists such as Gavin Schmidt, Michael Mann and David Karoly entering into debates with climate change denialists. Many scientists have found such debates to be unhelpful as they give the false impression of balance despite there being broad consensus among climate scientists that human greenhouse gas emissions have caused at least 1°C of global warming to date. In these debates, climate denialists recycle the same flawed arguments even though they have been debunked many times (see here). On the issue of being able to adapt to 5°C of global warming, while humans are resilient to some change, we know that, especially in the developing world, capacity to adapt to climate change is limited. A slew of recent studies has demonstrated that even at 2°C of global warming the impacts of climate change would be pervasive and devastating. Many studies show that severe heatwaves, which already kill many thousands of people in the current climate, would become much more deadly even with relatively little additional global warming, let alone 5°C of warming (for example, Saeed et al. (2021)[9]. In order to adapt to global warming humans require that the planet’s ecosystems also survive, but with only another 1°C of global warming the vast majority of the world’s coral reefs would be damaged beyond recognition[10]. Severe heat-induced bleaching and ocean acidification, both of which are linked to human-induced climate change, are damaging the world’s reefs already[11]. Hundreds of millions of people globally rely on there being healthy coral reefs[12], but even beyond 1.5°C global warming the survival of the world’s reefs is at threat. There are many, many other ways in which going beyond another 1°C of global warming would be extremely damaging, including extreme and continued sea level rise[13], and the increased possibility of triggering major disruptions to the Earth system with irreversible consequences (for example, this Nature article). The notion that society could adapt to, or even thrive, at 5°C of global warming is fanciful. Misinformation that masks the threats that global climate change poses has the potential to slow down our efforts to tackle this problem. It is vital that society is guided by the science and acts to reduce greenhouse gas emissions so future generations don’t pay the price.Timothy Osborn Professor, University of East Anglia, and Director of Research, Climatic Research Unit: This video has little scientific credibility. It builds up false strawmen about climate change and then pretends to demolish them with flawed reasoning and cherry-picked statements. Here are some examples: 1. The suggestion that the evidence for climate change is not being debated is false — evidence is continually being weighed up during the research process and in scientific publications and then in scientific assessment processes such as the IPCC. 2. The claim that sea levels have been rising for 20,000 years is false. It is likely that sea levels fell slightly over the last 2,000 years until the last century when they began rising and have recently accelerated. See Barnett et al. (2019)[14]. 3. The claim that because Netherlands have reduced coastal flooding means that the world could simply adapt to a global temperature rise of 5 degrees Celsius has no support at all. There is ample evidence for the colossal impacts that such an unprecedented rate of climate change would have and the evidence is that it would be overwhelmingly damaging. The evidence is summarised in the IPCC’s ‘reasons for concern’[15].Victor Venema Scientist, University of Bonn, Germany: The video is mostly innuendo, tossed together with incorrect and misleading claims and impossible expectations. A clear example of a misleading statement is describing the figure below as “the water has been rising for approximately 20,000 years”, while until recently the sea level in the age we built our infrastructure was remarkably stable (see figure 2). Figure 2—Created by Robert A. Rohde from published data and incorporated into the Global Warming Art project. Annotations: The statements quoted below are from the video; comments are from the reviewers (and are lightly edited for clarity). Claim: “Even if the planet warmed by 5 degrees, humans can adjust. People in Holland did… Are you telling me that people in Miami are so dumb that they are just going to sit there and drown?” … “the water has been rising for approximately 20,000 years and probably will continue” “but we can adapt, like Holland has.” Benjamin Horton Professor, Earth Observatory of Singapore: [Comment from a previous evaluation of a similar claim] False. Comparison of long tide gauge records and multi-centennial to millennial scale sea-level reconstructions from the same region indicates that the rate of rise during the instrumental period (since ~1850 CE) was significantly faster than it was during the late Holocene (the 4000–2000 years prior to ~1850 CE). The data demonstrate that an acceleration in the rate of sea-level rise occurred[16]. Patrick Brown Assistant Professor, San Jose State University: From approximately 20,000 years ago to approximately 4,000 years ago, there was a very large rise in sea level (approximately 125 meters or 410 feet) that occurred as the Earth emerged from the last glacial maximum (due to orbital changes). The fact that this occurred is largely irrelevant to the question of how much disruption multi-meter sea level rise (See figure below from Oppenheimer et al., 2019)[17] over the next several centuries will inflict on our current society. It is of course the case that various adaptation options are on the table (see figure below from Oppenheimer et al., 2019)[17]. The appropriate question is whether it costs more (in the broadest sense of the word cost) to reduce CO2 emissions or by continuing to emit indefinitely and choosing only adaptation. There are sufficient fossil fuels available to completely melt the Greenland and Antarctica ice sheets and raise global sea levels approximately 60 meters or 200 feet[18]. This would represent an astronomical cost much larger than the cost to transition to a near-zero emissions energy system[19]. Thus, relying 100% on adaptation fails the cost-benefit test in the long term. Claim: “the alarmists say hurricanes and other storms are getting worse. No they aren’t. You can take a look at all the hurricanes around the planet, we can see them since 1970 thanks to global satellite coverage and we can measure their power and we can add up their power. And there is no significant increase whatsoever. There is no relationship between hurricane activity and the surface temperature of the planet.” Kerry Emanuel Professor of Atmospheric Science, MIT: The most up-to-date research published in the Proceedings of the National Academy of Sciences demonstrates an increase in the proportion of hurricanes that become major hurricanes (Category 3-5) globally, supporting theoretical predictions that date back to 1987 (see figure below)[3]. As explained in a previous review, the latest consensus papers published in 2019 by Knutson et al. show a strong consensus that tropical cyclones will become more intense (but not necessarily more frequent) as the climate warms[2]. There is also a unanimous consensus that tropical cyclones will produce more rain, and in places with sufficient rain measurements, there is strong evidence for heavier rain events[2]. Figure 3—The proportion of major hurricane intensities to all hurricane intensities globally from 1979-2017. Data is binned into 3-year periods. The proportion of global major hurricanes increased by 25% over the 39-year time period analyzed. From Kossin et al. (2020)[4]. Patrick Brown Assistant Professor, San Jose State University: While there are no substantial trends in the global frequency of total hurricanes, major hurricanes or accumulated cyclone energy over the past few decades[20], it would be premature to say that there is no relationship between global mean surface temperature and global hurricane activity (broadly defined). For instance, know that there is a stronger relationship between surface temperature and hurricane rain rates than there is between surface temperature and hurricane wind speeds. The IPCC 2019 summarizes hurricane (or tropical cyclone, TC) projections going forward in the following paragraph: “Tropical cyclones (TCs) projections for the late 21st century are summarised as follows: 1) there is medium confidence that the proportion of TCs that reach Category 4-5 levels will increase, that the average intensity of TCs will increase (by roughly 1-10%, assuming a 2°C global temperature rise), and that average TCs precipitation rates (for a given storm) will increase by at least 7% per degree Celsius of sea surface temperature warming, owing to higher atmospheric water vapour content, 2) there is low confidence in how global TC frequency will change, although most modelling studies project some decrease in global TC frequency and 3) sea level rise will lead to higher storm surge levels for the TCs that do occur, assuming all other factors are unchanged (very high confidence).”[21] Claim: ”The Obama administration’s model projects that the amount of global warming that would be saved if we were going to go to zero emissions tomorrow (which would put us back to the stone age) would be 0.14°C. So no real effect on the climate.” Patrick Brown Assistant Professor, San Jose State University: This is a number corresponding to the United States acting in isolation. The United States currently represents about 14% of annual new CO2 emissions. So of course, eliminating only that portion of emissions will not solve the problem. However, if all the governments in the world were to act in coordination to bring emissions down to near zero, then global temperatures will stop increasing. The amount of global warming avoided from going to zero emissions globally (compared to burning all fossil fuels) is closer to 8 degrees Celsius which equates to approximately 22 degrees Fahrenheit over land. So global programs to limit emissions make an enormous difference. This is exactly why this process is mediated through entities like the United Nations – because it is a collective action problem that requires international cooperation. Claim: “The idea of carbon dioxide being pollution that just does harm and threatens the food supply is a myth. If you are really concerned about the plants, more carbon dioxide makes them not just grow faster but also makes them more water efficient. CO2 is a greenhouse gas but it also helps feed the world.” Sara Vicca Postdoctoral research fellow, University of Antwerp: The claim is misleading. Plants need CO2 to grow and they often grow better when the CO2 concentration increases. However, this fact is often abused to claim that increasing CO2 concentrations is mainly positive, while it also has several adverse effects. Increasing CO2 causes ocean acidification, which negatively affects marine life and threatens to disrupt the marine food web. And of course elevated CO2 warms the planet, thereby generating a cascade of effects from melting of glaciers and sea level rise to altered precipitation patterns and increasing frequency and intensity of extreme weather events such as heatwaves and droughts. These in turn threaten water and food supplies, and as climate change progresses, this is also likely to undo much of the beneficial effect that CO2 has on plant growth[5-8]. Patrick Brown Assistant Professor, San Jose State University: It is true that increases in atmospheric CO2 make photosynthesis more efficient and have resulted in ‘greening’ trends observable from space. See, for example, the IPCC statement below[7]. “Globally, greening trends have increased over the last 2-3 decades by 22-33%, particularly over China, India, many parts of Europe, central North America, southeast Brazil and southeast Australia (high confidence). This results from a combination of direct and indirect factors (i.e. CO2, fertilisation, extended growing season, nitrogen deposition […])” However, this CO2 fertilization effect is just one of a myriad of influences on crop productivity and quality. Global crop models take into account many potential changes (including the fertilization effect from CO2) and tend to indicate that the net effect of increased CO2 (including its climate affects) will cause yields to decrease[5]: “At the global scale, Iizumi et al. (2018) used a counterfactual analysis and found that climate change between 1981 and 2010 has decreased global mean yields of maize, wheat, and soybeans by 4.1, 1.8 and 4.5%, respectively, relative to preindustrial climate, even when CO2 fertilisation and agronomix adjustments are considered.”[22] Also, increased atmospheric CO2 tends to decrease the nutritional quality of crops[5,22]. Kristie Ebi Professor, University of Washington: Higher CO2 concentrations reduce the nutrient density of major cereal crops, including wheat and rice. At CO2 concentrations expected later this century, protein declines about 10%, micronutrients about 5%, and B-vitamins about 30%[23]. This matters because there are more than 2 billion people worldwide with micronutrient deficiencies (Micronutrient Deficiency – Our World in Data). This is significantly higher than the numbers of people who are food insecure. Estimates of the numbers of people potentially affected are in the hundreds of millions. [The idea that increased CO2 so far is helping feed the world is an exaggeration as explained by Professor Philip Robertson in a previous review:] G Philip Robertson Professor, Michigan State University: In general, CO2 has had a positive effect on crop growth, but it’s impossible to separate historical effects from the greater effects of genetics and nitrogen and other inputs. However, it’s generally considered to be a fraction of those. We know better future effects because we have CO2 fertilization experiments in the field comparing present to future CO2 levels. Those experiments suggest that corn may have about a 1% gain [because of increased CO2] and soybeans 3-4 times that. However, these gains will almost certainly be offset by yield declines associated with the temperature increases caused by elevated CO2, which are well known. Historically, it’s worth noting that we had elevated CO2 long before we had the green revolution, and crop yields didn’t increase much until the green revolution. You can see this in graphs of average US corn yields from 1900. Source: University of Nebraska-Lincoln Claim: “It is not the case that we “have twelve years to act” Patrick Brown Assistant Professor, San Jose State University: I agree with the sentiment that there is very weak evidence that crossing 1.5°C represents some unique tipping point into catastrophe. This claim is made in regards to a 2018 Intergovernmental Panel on Climate Change report[24]. That report was on the impacts associated with global warming of 1.5°C (2.7°F) above preindustrial levels as well as the technical feasibility of limiting global warming to such a level. In 2018, the year 2030 was 12 years away and 2030 was deemed the earliest year in which the 1.5°C threshold could be crossed. The media coverage of the report did often portray it as saying we have 12 years (until 2030) to act on climate else catastrophe would ensue but the report did not actually make such claims. The report was not tasked with defining a level of global warming which might be considered to be catastrophic (or any other alarming adjective). Rather, the report was tasked with evaluating the impacts of global warming of 1.5°C (2.7°F) above preindustrial levels, and comparing these to the impacts associated with 2.0°C (3.6°F) above preindustrial levels as well as evaluating the changes to global energy systems that would be necessary in order to limit global warming to 1.5°C. To summarize, the IPCC’s literature review found that impacts of global warming at 2.0°C are worse than at 1.5°C[24]. There was no claim by the IPCC that we have 12 years to avoid catastrophe. Therefore, I do not take issue with the Facebook video portraying this framing as a myth.REFERENCES: 1 – Lambeck et al. (2014) Sea level and global ice volumes from the Last Glacial Maximum to the Holocene. PNAS. 2 – Knutson et al. (2020) Tropical Cyclones and Climate Change Assessment: Part II: Projected Response to Anthropogenic Warming. Bulletin of the American Meteorological Society. 3 – Kossin et al. (2020) Global increase in major tropical cyclone exceedance probability over the past four decades. PNAS. 4 – Liu et al. (2019) Causes of large projected increases in hurricane precipitation rates with global warming. npj Climate and Atmospheric Science. 5 – Moore et al. (2017) New science of climate change impacts on agriculture implies higher social cost of carbon. Nature. 6 – Terrier et al. (2019) Nitrogen and phosphorus constrain the CO2 fertilization of global plant biomass. Nature Climate Change. 7 – Shukla et al. (2019) Technical Summary:, 2019. In: Climate Change and Land: an IPCC special report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems. IPCC report. 8 – Mbow et al. (2019) IP Food Security. In: Climate Change and Land: an IPCC special report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems. IPCC report. 9 – Saheed et al. (2021) Deadly Heat Stress to Become Commonplace Across South Asia Already at 1.5°C of Global Warming. Geophysical Research Letters. 10 – Hughes et al. (2017) Coral reefs in the Anthropocene. Nature. 11 – Hughes et al. (2017) Global warming and recurrent mass bleaching of corals. Nature. 12 – Pendleton et al. (2016) Coral Reefs and People in a High-CO2 World: Where Can Science Make a Difference to People? Plos One. 13 – Nauels et al. (2019) Attributing long-term sea-level rise to Paris Agreement emission pledges. PNAS. 14 – Barnett et al. Late Holocene sea level. Past Global Changes. 15 – O’Neill et al. (2017) IPCC reasons for concern regarding climate change risks. Nature Climate Change. 16 – Kopp et al (2016) Temperature-driven global sea-level variability in the Common Era. PNAS. 17 – Oppenheimer et al. (2019) Sea Level Rise and Implications for Low-Lying Islands, Coasts and Communities. In: IPCC Special Report on the Ocean and Cryosphere in a Changing Climate. 18 – Winkelmann et al. (2015) Combustion of available fossil fuel resources sufficient to eliminate the Antarctic Ice Sheet. Science Advances. 19 – Brown et al. (2020) Break-even year: a concept for understanding intergenerational trade-offs in climate change mitigation policy. Environmental Research Communications. 20 – Blunden and Arndt (2020) State of the Climate in 2019. Bulletin of the American Meteorological Society. 21 – IPCC (2019) Technical Summary. In: IPCC Special Report on the Ocean and Cryosphere in a Changing Climate. 22 – Iizumi et al. (2018) Crop production losses associated with anthropogenic climate change for 1981–2010 compared with preindustrial levels. International Journal of Climatology. 23 – Zhu et al. (2018) Carbon dioxide (CO2) levels this century will alter the protein, micronutrients, and vitamin content of rice grains with potential health consequences for the poorest rice-dependent countries. Science Advances. 24 – IPCC (2018) Summary for Policymakers. In: Global Warming of 1.5°C. An IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty. World Meteorological Organization."
https://science.feedback.org/review/a-third-of-antarctic-ice-shelf-risks-collapse-at-4c-above-pre-industrial-levels-as-accurately-described-in-cnn-article/,Accurate,"CNN, Amy Woodyatt, 2021-04-09","""A third of Antarctic ice shelf risks collapse as our planet warms""",,Accurate: A recent study found that 34% of the Antarctic ice shelf was at risk of collapse at 4°C above pre-industrial levels.  Lacks context: The claim doesn’t provide a timescale for when this collapse might occur or mention that not all ice shelves are susceptible to collapse. ,Ice shelves are floating sheets of ice that are connected to land masses. They gain and lose surface ice over time depending on snowfall and atmospheric and ocean temperatures. A recent study found that 34% of the Antarctic ice shelf is vulnerable to collapse under a future climate scenario that is 4°C above pre-industrial levels. ,"""A third of Antarctic ice shelf risks collapse as our planet warms""","1 – Gilbert and Kittel (2021) Surface melt and runoff on Antarctic ice shelves at 1.5°C, 2°C and 4°C of future warming. Geophysical Research Letters.","Review: The claim that “A third of Antarctic ice shelf risks collapse as our planet warms” appeared in a CNN article and CNN Climate Instagram post published in April 2021, receiving more than 22,000 interactions on Facebook and Instagram, according to the social media analytics tool CrowdTangle. The claim is based on a study recently published in Geophysical Research Letters that estimated surface melt and runoff on Antarctic ice shelves under three future global warming scenarios[1]. Ice shelves are floating sheets of ice that are connected to land masses. They gain and lose ice at their surface over time depending on a variety of factors, including snowfall and the temperature of the atmosphere and the ocean. Ice shelves grow when snowfall accumulates on their surface and shrink when surface ice melts during the summer. This balance between ice gain and loss is referred to as the surface mass balance. While ice shelves don’t directly contribute to sea level rise, they play a critical role in holding back glaciers. If ice shelves collapse, glacial ice can flow more easily into the ocean, contributing to sea level rise. One way ice shelves can collapse is through a process called hydrofracture. This occurs when surface melt runs into gaps in the ice shelf during warmer months. When this water freezes, it expands, causing fractures and potentially the disintegration of the ice shelf. In the recent study, scientists modeled ice melt, runoff, and the surface mass balance of Antarctic ice under three global warming scenarios: 1.5°C, 2°C, and 4°C above pre-industrial levels. As Dr. Ella Gilbert, the lead author of the study describes below, 34% of the area of the Antarctic ice shelf is vulnerable to collapse under the 4°C scenario, consistent with the claim (see figure 1). Figure 1—Average ice shelf runoff for the entire Antarctic ice shelf (Antarctica) and three regions of the ice shelf (Antarctic Peninsula, East Antarctica, and West Antarctica) from 1980 to 2100. Colors represent different model simulations and the black line shows the mean of all models. Ice shelf runoff was modeled for three future climate scenarios (1.5°C, 2°C, and 4°C above pre-industrial levels) and the time periods of these are indicated in Antarctica panel. From Gilbert and Kittel (2021)[1]. While the article and Instagram post accurately described results of the study, scientists who reviewed this claim thought it could benefit from a bit more detail. Specifically, they note that not all ice shelves are susceptible to collapse and that the article didn’t specify a timeline for when collapse of the Antarctic ice shelf might occur. Scientists’ Feedback: Ella Gilbert Research Scientist, British Antarctic Survey: Overall I think the Instagram post isn’t inaccurate, maybe just omits some of the details. CNN did actually write a pretty good article about the paper, I guess the nuances just got a bit lost in the Instagram post. One of the main conclusions of the study is that 34% of ice shelf area​ is susceptible to hydro-fracturing driven collapse at 4 degrees above pre-industrial temperatures. This value increases from 9% in the historical period to 14% and 18% at 1.5 and 2 degrees, respectively. That means that keeping warming to 2 degrees results in a halving of the ice shelf area at risk. The caveats are that many ice shelves are dynamically stable and therefore unlikely to collapse unless their dynamical regime is altered (e.g. by very large calving events), which is virtually impossible for some ice shelves (for example the George VI ice shelf is surrounded on three sides by rock, making it extremely resilient to change despite high melt rates. We identify 4 ice shelves – the Larsen C, Wilkins, Pine Island and Shackleton ice shelves to be most vulnerable at 4 degrees. Twila Moon Research Scientist, University of Colorado, Boulder: The statement in the Instagram post and article headline is accurate but incomplete. The research looked at ice shelf stability under a range of future warming scenarios, finding more vulnerability at higher temps (future increase of 4C especially). So one point of the paper is the importance of limiting Earth warming. Other details that aren’t reflected with the short published statement is the timescale of collapse. So much about ice loss on Earth is about how quickly ice is lost. Not including this information can leave the audience to make any number of assumptions. I found that the article itself was good at providing accurate information. There is still a missing time elements in some cases, but the article has much more detail on both the research article and how that connects with other science findings, such as the urgent need for action to limit future warming. I didn’t note anything that I think requires specific clarification, as I felt the article overall was appropriate. READ MORE: The first author of the paper, Dr. Ella Gilbert, wrote several articles summarizing the study’s findings for Carbon Brief and The Conversation."
https://science.feedback.org/review/in-viral-turning-point-usa-video-candace-owens-and-charlie-kirk-falsely-claim-there-is-no-evidence-of-global-warming-and-scientists-dont-know-the-cause/,Inaccurate,"Turning Point USA, Candace Owens, Charlie Kirk, 2021-04-11","There is no factual data to back up global warming; real scientists don’t know whether CO<sub>2</sub>, solar sunspots or natural activity cause global warming",,"Factually inaccurate: It is a measured fact that Earth has warmed over the past century, as shown by atmospheric and oceanic temperature records.   Incorrect: : Anthropogenic emissions of CO2 and other greenhouse gases are the leading cause of global mean temperature rise in the industrial era. Solar activity plays only a minor role in current climate changes, and is not a major contributor to the global warming trend observed over the past decades. ","Scientists have unequivocally demonstrated increases in the temperature of the Earth’s atmosphere and oceans over the past century. The rate of global warming has been accelerating since the 1980s, and the last decade was the warmest on record. Global warming also affects the melting of sea and land ice, and induces changes in ecosystems, such as species migration to higher latitudes or higher elevations. Numerous scientific studies established a clear link between human-caused increases in greenhouse gases and global warming.","They changed it from global warming to climate change. Do you know why ? Because, when scientists are looking into global warming, there was no factual data to back up their argument. Real scientists are still debating whether CO<sub>2</sub> or solar sunspots or natural variability cause global warming",,"Review: The claim appeared in a video posted on Facebook and Instagram by Turning Point USA, a partisan organization that advocates for conservative policies on high school, college, and university campuses The video, featuring Charlie Kirk, founder of Turning Point USA, and Candace Owens, received more than 640,000 views on Facebook alone since it was published on 11 April 2021. First, there is no evidence to support the claim that “they changed from global warming to climate change”. Climate scientists use both terms in the scientific literature, as they refer to two distinct, but causally-related phenomena. Global warming describes the long-term trend of increasing average global temperature, whereas climate change refers to changes in the various measures of climate. These measures include temperature, as well as precipitation, wind patterns, drought prevalence, and the occurrence of other extreme events. In 2005, the National Academy of Sciences stated that “the phrase ‘climate change’ is growing in preferred use to ‘global warming’ because it helps convey that there are changes in addition to rising temperatures”[1]. There’s no evidence that a complete shift in terminology took place, and there’s no reason to do so, contrary to the video’s claim. Second, many lines of scientific evidence unambiguously demonstrate that the Earth’s surface is experiencing rapid global warming. The first line of evidence is the continuous record of surface temperatures recorded at thousands of weather stations worldwide. Some records date back to the early eighteenth century. When averaged together, these data indicate a clear increasing trend in the Earth’s surface temperature. According to the 2018 IPCC report, “Human activities are estimated to have caused approximately 1.0°C of global warming above pre-industrial levels, with a likely range of 0.8°C to 1.2°C”[2]. And the rate of global warming is accelerating, as stated in NOAA’s latest report, “the global annual temperature has increased at an average rate of 0.08°C (0.14°F) per decade since 1880 and over twice that rate (+0.18°C / +0.32°F) since 1981”. Furthermore, some of the warmest years in the 141-year record occurred in the last decade, with 2016 being the warmest and 2020 being the second warmest (see figure below). Figure—Global temperature anomaly data relative to the 20th century average temperature from the Global Historical Climatology Network-Monthly data set and International Comprehensive Ocean-Atmosphere Data Set. These data sets show consistent global warming trends. From NOAA. Another line of evidence of global warming is the increase in ocean heat content observed by scientists over the past decades. The increased concentration of heat-trapping greenhouse gases in the atmosphere generated an energy imbalance in the Earth’s climate system of almost 1 W m−2 [3]. This means that Earth radiates less energy to space than it receives from the Sun, essentially less heat is going out, than is going in. Over 90% of this excess heat accumulates in the ocean because of its large heat capacity compared to the atmosphere. Over the past decades, scientists have observed an increase in ocean heat content. Specifically, each decade has been warmer than the preceding decade in terms of ocean heat content, and 2020 hit a record high (see figure below). Figure—Global upper 2000 m ocean heat content (OHC) from 1958 through 2020. The histogram presents annual anomalies relative to a 1981-2010 baseline, with positive anomalies shown as red bars and negative anomalies as blue. Units : Zetta Joules (ZJ, equals to 1021 Joules). From Advances in Atmospheric Science. According to Cheng et al. (2021), “the most recent data indicate that the ocean heat content in the upper 2000 m layer of the world’s oceans has increased with a mean rate of 5.7 ± 1.0 ZJ yr−1 for the 1958−2020 period”[4]. (The unit is in ZettaJoules, which is equivalent to 1021 Joules, that is millions of millions of billions). The authors also found that there is a more rapid increase that began in the 1980s. The average annual increase from 1986 to 2020, is almost eight times larger than the linear rate from 1958~1985. Sea level rise, which scientists have observed since 1900, is another line of evidence that global warming is occuring[5]. Sea level rise is caused, in part, by the thermal expansion of the oceans and, in part, by the melting of glaciers on land. In addition to rising temperatures of Earth’s atmosphere and oceans, global warming has caused land and sea ice to melt. “Over the last decades, global warming has led to widespread shrinking of the cryosphere”, as stated in a special report on the ocean and cryosphere released by the IPCC[6]. “Most glaciers are shrinking (high confidence), the Greenland and Antarctic ice sheets are losing mass (high confidence), sea ice extent in the Arctic is decreasing (very high confidence), Northern Hemisphere snow cover is decreasing (very high confidence), and permafrost temperatures are increasing (high confidence).” Multiple studies demonstrated that ecosystems are also responding to global warming in numerous ways[7]. For example, many ecosystems experience earlier springs and later falls compared to the 20th-century averages. Global warming is also driving large-scale shifts in species distributions, as many animals and plants are moving higher in elevation and latitude to find suitable habitats[8]. Finally, the claim that real scientists don’t know whether CO2 or solar sunspots or natural variability causes global warming is incorrect. According to the IPCC, the current scientific consensus is that variations in solar activity only play a very small role in Earth’s recent climate[9]. Human-produced greenhouse gases are the primary cause of global warming trends and their effects are much stronger than those due to recent variations in solar activity. The human-caused drivers of global warming and climate change are well understood and reflect decades of research on the topic[10]. For example, an analysis of the major factors that influence global surface temperatures, and how their effects change over time, found that human-caused increases in greenhouse gas emissions account for 100% of the warming trends observed over the past century, given that humans also cause cooling effects such as the emissions of particles (aerosols) (see figure below). Figure—The estimated role of different factors influencing global surface temperatures from 1850 to 2017. Observed temperatures are shown in black dots. Global warming over the past 150 years was primarily driven by greenhouse gas emissions (red). Solar activity (yellow) is a minor contributor and follows the Sun’s natural 11-year cycle. From Carbon Brief. The role of human activity in the increase in global CO2 concentration is also unquestionable. Scientists are now able to track fossil fuel emissions by measuring the level of radioisotope carbon-14 (14C) in the air[11]. This natural isotope has a half-life of 5,700 years and is widely used in archeological studies for dating. Fossil fuels are completely devoid of 14C, because they have been buried for millions of years, and have lost all of it through radioactive decay. Therefore, the degree of 14C-depletion of the CO2 in air samples reflects the contribution from fossil fuel combustion. Kirk dismisses the significance of the scientific consensus on the subject of human-caused global warming, but scientific consensus is important insofar as it reflects the consensus of evidence that supports or refutes competing hypotheses, and scientists with expertise on the subject are able to assess the evidence. In the case of climate change, the evidence accumulated over the past few decades is consistent with the explanation that human activities are the cause of the observed increases in global temperature. Kirk says that “we don’t vote on gravity, we don’t vote on Newton’s second law, we prove it”. But this is also a misunderstanding of how science works. Scientists do not “prove” that a hypothesis is valid in the mathematical sense of the term, instead they propose all the hypotheses that could explain a given phenomenon (here the increase in global temperature) and then they collect data to evaluate whether the data is consistent or inconsistent with each hypothesis. For instance, the hypothesis that solar activity explains current global warming trends was ruled out since, among other pieces of evidence, the entire atmosphere hasn’t warmed[12], which would be the case if that hypothesis was true. The hypothesis that natural variation within the climate system explains global warming was also ruled out, as no natural mechanism has been found that could explain the trends observed over the past century. In addition, a natural cycle coming from the ocean for instance would redistribute heat in the ocean and not simply increase the amount of heat in the oceans as observed. Contrary to Kirk’s assertion, it is the failure to disprove the theory of gravity that led scientists to accept its validity. The same is true for global warming: hypotheses stating that “there is no warming” or that “warming is caused by something else other than human activity” fail to propose a verifiably valid explanation for the warming trends observed, making the human-influence explanation the only valid one. Scientists’ Feedback: Baird Langenbrunner Associate Editor, Nature Climate Change: There has been very clear and measurable warming since this time period [industrial revolution]—this has been confirmed time and time again using station data and satellite measurements and it matches well with predictions based on increases in greenhouse gas concentrations. Even in the brief periods when the surface temperature warms less quickly, the oceans continue to warm, which together with the atmosphere accounts for all the extra heat predicted by increased greenhouse gas concentrations. Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: This claim is not accurate. Global temperature datasets, developed by a number of independent research groups, show robust warming in the troposphere and at the Earth’s surface. The radiative effect of carbon dioxide has also been observed[13]. Considering multiple lines of evidence, the IPCC concluded that it is “extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century.” More recent analysis of satellite data shows that tropospheric warming from the satellite record is pronounced and cannot be explained by natural climate variability alone[14]. Gavin Schmidt Director, NASA Goddard Institute for Space Studies: There is indeed overwhelming evidence for warming in the last century. [The] claim that no one knows the attribution of this to human impacts is not a valid description of the state of knowledge. There are indeed plenty of studies that use statistical or model-based fingerprints to assess this and they overwhelmingly find a dominance of human activities over natural forcings or internal variability. For the more recent period (1950 onwards) the claims are even stronger—that effectively all the warming is caused by human activity with only a ~10% uncertainty due to internal variability.UPDATE 20 May 2021: Charlie Kirk has issued a correction saying that their claims were false (see the screenshot below). The video has now been deleted.REFERENCES: 1 – The National Academy of Sciences (2005) Understanding and responding to climate change. 2 – IPCC (2018) Summary: for Policymakers. IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways. 3 – Trenberth et al. (2014) Earth’s energy imbalance. Journal of Climate. 4 – Cheng et al. (2021) Upper Ocean Temperatures Hit Record High in 2020. Advances in Atmospheric Science. 5 – Frederikse et al. (2020) The causes of sea-level rise since 1900. Nature. 6 – IPCC (2019) Framing and context of the report. IPCC Special Report on the Ocean and Cryosphere in a Changing Climate. 7 – Weiskopf et al. (2020) Climate change effects on biodiversity, ecosystems, ecosystem services, and natural resource management in the United States. Science of the Total Environment. 8 – Burrows et al. (2011) The Pace of Shifting Climate in Marine and Terrestrial Ecosystems. Science. 9 – IPCC (2013) Anthropogenic and natural radiative forcing. Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. 10 – Hegerl and Zwiers (2011) Use of models in detection and attribution of climate change, Wires Climate Change. 11 – Basu et al. (2020) Estimating US fossil fuel CO2 emissions from measurements of 14C in atmospheric CO2, PNAS. 12 – Ogawa et al. (2014) Upper atmosphere cooling over the past 33 years, Geophysical Research Letters. 13 – Feldman et al (2015) Observational determination of surface radiative forcing by CO2 from 2000 to 2010, Nature. 14 – Santer et al. (2017) Tropospheric Warming Over The Past Two Decades, Scientific Reports."
https://science.feedback.org/review/deserts-cool-the-planet-by-reflecting-solar-radiation-to-space-vegetated-areas-have-an-overall-warming-effect-so-planting-trees-in-deserts-doesnt-necessarily-cool-the-planet-the-guardian/,Inaccurate,"The Guardian, Steve Rose, Ties Van der Hoeven, 2021-03-20","""Deserts are heat producers, reflecting around 60% to 70% of the solar energy that falls on them straight back into the atmosphere.""; ""If we want to do something about global warming, we have to do something about deserts.""",,"Inaccurate: Deserts reflect solar radiation to space through the atmosphere, cooling the planet. Vegetated areas have an overall warming effect on the planet because they absorb sunlight and increase atmospheric water vapor. Claim in The Guardian article that we need to plant forests in the desert to combat climate change isn’t accurate.","Deserts reflect solar radiation to space through the atmosphere. Because solar radiation isn’t absorbed by the atmosphere, deserts have a cooling effect on the planet. While vegetated areas can reduce temperatures at the ground level locally due to evapotranspiration, they have an overall warming effect on the planet because they absorb more sunlight and heat than deserts. That being said, preventing forests from being cut is an effective way to limit global warming via another mechanism: preventing the carbon stored in trees from being released into the atmosphere.","""Deserts are heat producers, reflecting around 60% to 70% of the solar energy that falls on them straight back into the atmosphere."" ; ""In addition to sequestering carbon, green areas also help cool the planet"" ; Vegetation reduces temperature and solar reflection, creating a stable climate; ""If we want to do something about global warming, we have to do something about deserts.""","1 – Pierrehumbert (1995) Thermostats, Radiator Fins, and the Local Runaway Greenhouse. Journal of the Atmospheric Sciences. 2 – Goffner et al. (2019) The Great Green Wall for the Sahara and the Sahel Initiative as an opportunity to enhance resilience in Sahelian landscapes and livelihoods. Regional Environmental Change. 3 – Charney (1975) Dynamics of deserts and drought in the Sahel. Quarterly Journal of the Royal Meteorological Society. 4 – Yosef et al. (2018) Large-scale semi-arid afforestation can enhance precipitation and carbon sequestration potential. Scientific reports. 5 – Kemena et al. (2018) Atmospheric feedbacks in North Africa from an irrigated, afforested Sahara. Climate Dynamics. 6 – Pausata et al. (2016) Impacts of dust reduction on the northward expansion of the African monsoon during the Green Sahara period. Earth and Planetary Science Letters. 7 – Muschitiello et al. (2015) Arctic climate response to the termination of the African Humid Period. Quaternary Science Reviews. 8 – Davies et al. (2015) The impact of Sahara desertification on Arctic cooling during the Holocene. Climate of the Past.9 – Keller et al. (2014) Potential climate engineering effectiveness and side effects during a high carbon dioxide-emission scenario. Nature Communications.","Review: The claim that deserts warm the planet was published in an article by The Guardian in March 2021, which received more than 30,000 interactions on Facebook according to the social media analytics tool CrowdTangle. The article makes several inaccurate or misleading claims about the role deserts play in global warming and climate change. Specifically, the article makes the inaccurate claim that “Deserts are heat producers, reflecting around 60% to 70% of the solar energy that falls on them straight back into the atmosphere”. As the reviewers describe below, deserts cool rather than warm the planet[1]. Deserts reflect solar radiation to space, meaning it isn’t absorbed by the atmosphere. The article also claims that areas covered by vegetation cool the planet, however, these dark areas can have a warming effect on the planet because of their albedo effect, which describes how much sunlight is absorbed versus reflected. While vegetated areas can have a cooling effect at the ground level in local regions due to evaporation, they have a warming effect in terms of the global energy balance by increasing atmospheric water vapor, as the reviewers describe below. Furthermore, planting trees has an indirect cooling effect as the trees absorb CO2 while they grow, however, if these habitats are lost through harvesting, natural disasters, or other events, this CO2 will be released. The effects of vegetated areas on temperature are complex and vary between regions. Scientists’ Feedback: “Deserts are heat producers, reflecting around 60% to 70% of the solar energy that falls on them straight back into the atmosphere.” Matthew Huber Professor, Purdue University: Deserts reflect sunlight through the atmosphere TO SPACE, where it is lost from the atmosphere. Thus deserts cool the planet. Sunlight is transmitted through the atmosphere, not absorbed. Raymond Pierrehumbert Professor, University of Oxford: The statement that “Deserts are heat producers” is absolutely wrong. It is true that they reflect back 60-70% of the sunlight but the reflected light absolutely does not get absorbed by the atmosphere. It just goes right back to space where it came from, and this happens efficiently over deserts since the skies tend to be clear and cloud free. Further, when the surface of the desert heats up, the infrared it radiates gets out to space easily, because the air is very dry and cloud free. Taken together, deserts cool the planet, they don’t warm it. The claim in the Guardian article that, “Deserts are heat producers, reflecting around 60% to 70% of the solar energy that falls on them straight back into the atmosphere,” misunderstands the impact of reflection on the planetary energy balance, as well as the role of deserts in global climate. Reflection (or albedo) is a cooling mechanism, not a warming one. Deserts would be even hotter if the sand were black. Because solar radiation that reaches the surface cannot be transmitted through the solid earth, it can only be absorbed at the surface (where the energy is used to evaporate water or raise the temperature of the ground), or the light can be reflected away. Of the light that is reflected upward, most of it passes through the atmosphere and is lost to space, as if it never existed. This is for the same reason light from the Sun coming “downward” reached the surface in the first place– Earth’s atmosphere, especially in the dry subtropics–is rather transparent to solar radiation. If instead a small amount of solar radiation is absorbed by the atmosphere on its passage upward (or downward), this is still not much different than if it had been absorbed directly at the surface anyway. That absorbed energy is still in the coupled surface-atmosphere system. Reflection does not create a source of “new” energy, which of course must be conserved. Although tropical deserts are hot locally, they are unique regions for the energy balance of the planet. Not only does desert sand have a high albedo, but the hot surface also emits infrared radiation strongly to space through a relatively dry and cloud-free atmosphere. This lack of greenhouse trapping also helps deserts get cold at night. In fact, because the Saharan and Arabian desert regions are bright and effectively lose infrared energy (both cooling mechanisms), the annual mean top-of-atmosphere net radiation is negative over those regions (see figure below), which is unusual for a land region near the equator. Over the Amazon in South America, for example, the outgoing thermal radiation is instead relatively low due to the high moisture content and energy emanating from cold cloud tops. Figure 1—Annual-mean planetary albedo, outgoing thermal (longwave) radiation, and net top-of-atmosphere radiation from CERES EBAF averaged from 2005-2015. Net radiation is incoming solar minus outgoing solar (reflection) minus outgoing thermal (emission) radiation. Radiative heating/cooling in the tropics is tightly coupled to vertical motion. The net radiative loss over the large deserts is balanced largely by atmospheric heat transport in the form of air with a high potential temperature flowing in at high altitudes, and descending while being heated adiabatically. This branch of the Hadley circulation continuously provides warm air to the lower atmosphere through subsidence and carries moisture out of the region in near-surface equatorward outflow. The desert surface also has limited evaporation, and so these regions get quite hot, yet are so-called “radiator fins”for the low latitudes that cool the planet[1]. Indeed, the moist part of the deep tropics would be close to a runaway greenhouse state, in isolation, if not for heat transport to the extra-tropics and emission to space from the dry zones in between. “In addition to sequestering carbon, green areas also help cool the planet.” Matthew Huber Professor, Purdue University: Green areas have lower albedo than shiny, high albedo deserts, thus their impact on the solar part of the energy budget is warming. Raymond Pierrehumbert Professor, University of Oxford: Greening would take up some carbon, but “sequestering” is the wrong word since the carbon isn’t very securely stored. It is right near the surface where it can easily oxidise back to CO2. The ability of land practices to cause more carbon uptake is real, but the effect is exaggerated in terms of the proportion of the climate problem it can deal with. But green areas do not cool the planet. By absorbing more sunlight, they actually warm the planet. The statement confuses the local surface energy balance with the global balance. By providing a moist and shaded surface, the evaporation helps cool the ground locally. However, the evaporation just moves heat to another part of the atmosphere. Further, a sufficiently green moist area can cause warming by increasing atmospheric water vapour, though the amount of warming depends on what kind of clouds form, and where. (Clouds reflect sunlight, but both water vapour and clouds add to the greenhouse effect). “In areas covered by vegetation, much of that solar energy is instead used in evapotranspiration: the process of condensation and evaporation by which water moves between plants and the atmosphere.” Matthew Huber Professor, Purdue University: It is true that locally most sunlight in these regions drives evaporation, not local sensible heating. But this latent heat gain is transferred into latent heat release and warming in convergence (raining) regions, it is not lost to the energy budget of the tropics. Raymond Pierrehumbert Professor, University of Oxford: Yes, evapotranspiration increases, but this only causes local cooling, which is made up for where the energy of the water vapour is released, when it condenses back into the ocean. On the balance, evaporation does not cause a cooling of the planet. Evapotranspiration can move energy away from the local surface, but it cannot move energy into outer space! Only infrared radiation or reflection of sunlight can do that. “ ‘If vegetation comes back, you increase cover, you reduce temperature, you reduce solar reflection, you start creating a stable climate,’ says Van der Hoeven. ‘If we want to do something about global warming, we have to do something about deserts.’ ” Matthew Huber Professor, Purdue University: Since deserts reflect back solar radiation and are associated with dryer upper atmosphere (and hence a reduced water vapor greenhouse effect) deserts are a vital part of maintaining a relatively cool tropical mean temperature. Raymond Pierrehumbert Professor, University of Oxford: It is absolute rubbish to say that “If we want to do something about global warming, we have to do something about deserts.” There may be local benefits to greening a desert, in terms of the local environment or food production, but deserts cool the planet as a whole, they don’t warm them. Whether human interventions can produce a “stable” greened climate is controversial. The great greening of the Sahara that happened some thousands of years ago was driven by changes in the Earth’s orbital characteristics, which the proposed human interventions don’t duplicate. Coming back to local afforestation/reforestation and greening efforts in arid places such as Africa or Australia, which have either been proposed or are currently being implemented [e.g., Green the Sinai in the Guardian article, The Great Green Wall (see e.g., Goffner et al., 2019[2])], the goal is usually to geoengineer regional climate toward wetter conditions, which may come with many benefits for local populations. It is also reasonable to expect that in some areas there will be local cooling due to enhanced evapotranspiration and cloud cover, despite the reduced surface albedo due to the darker (vegetated) surface. The reduction in surface albedo could shift the tropical rainbelt known as the Inter Tropical Convergence Zone northward, bringing rainfall to the desert, a biogeophysical feedback recognized by Charney in the 1970s[3]. However, the broader climate effects and sustainability of such efforts, even if scaled up beyond the Sinai domain, are complicated. Modeled climate impacts of such proposals even locally are complex, with Sahara greening altering local atmospheric circulation, such as the African easterly jet and the intensity of the monsoon winds in the Sahel (e.g., Yosef et al. 2018; Kemena et al. 2018[4,5]), or changing dust fluxes (as is important during past “Green Sahara” episodes)[6]; that dust also contain iron and other nutrients that fertilize the ocean, which could affect productivity in other regions. The self-sustainability of this geoengineering is also in question, since much of the evapo-transpired water is precipitated in areas removed from the greening project (e.g., Kemena et al. 2018[5]). Because the desertification/greening in Africa can have impacts globally, even in the polar regions[7,8], more comprehensive assessments with Earth system models are needed before deployment, in addition to discussions of ethics and geopolitics. For example, in Keller et al. (2014), afforestation experiments actually increase global temperature due to albedo reductions (see figure below) highlighting potential far-field side effects of such proposals[9]. Figure 2—Plots taken from Keller et al. (2014), showing changes in surface air temperature, carbon inventories, primary productivity, and surface albedo, in climate engineering experiments using the University of Victoria Earth system model (UVic) of intermediate complexity[9]."
https://science.feedback.org/review/solar-geoengineering-isnt-happening-or-damaging-the-planet-aircraft-contrails-are-formed-by-water-vapor-not-chemicals/,Incorrect,"Geoengineering Watch, Dane Wigington, 2021-03-10","""The intentional dimming of direct sunlight by aircraft dispersed particles, a form of global warming mitigation known as “Solar Radiation Management”, has and is causing catastrophic damage to the planet’s life support systems.""",,Incorrect: Aircrafts produce contrails when water vapor from jet exhaust condenses at high altitudes. Scientists agree that there is no evidence of chemtrails or solar geoengineering. ,"Solar geoengineering describes hypothetical strategies to combat global warming by reflecting sunlight away from the Earth. There is no scientific evidence that solar geoengineering is happening or having catastrophic effects on the planet or human health. There is also no scientific evidence of aircraft chemtrails. Instead, aircrafts produce contrails when water vapor from jet exhaust mixes with the atmosphere and condenses at high altitudes.","""Global climate engineering operations are a reality. Atmospheric particle testing conducted by GeoengineeringWatch.org has now proven that the lingering, spreading jet aircraft trails, so commonly visible in our skies, are not just condensation as we have officially been told. ... The intentional dimming of direct sunlight by aircraft dispersed particles, a form of global warming mitigation known as “Solar Radiation Management”, has and is causing catastrophic damage to the planet’s life support systems. The highly toxic fallout from the ongoing geoengineering operations is also inflicting unquantifiable damage to human health.""","1 – Shearer et al. (2016) Quantifying expert consensus against the existence of a secret, large-scale atmospheric spraying program. Environmental Research Letters. 2 – Kärcher (2018) Formation and radiative forcing of contrail cirrus. Nature. 3 – Trisos et al. (2018) Potentially dangerous consequences for biodiversity of solar geoengineering implementation and termination. Nature Ecology & Evolution.4 – Parker and Irvine (2018) The Risk of Termination Shock From Solar Geoengineering. Earth’s Future.","Review: The claims that climate engineering is happening and causing catastrophic damage to the planet’s life support systems was published in a YouTube video by Dane Wigington of Geoengineering Watch. The video received more than 155,000 views, as of 24 March 2021. These claims were also repeated in an article published by Health Impact News. The video incorrectly claims that climate engineering is happening and that jet aircraft trails are not condensation, but dispersed particles that dim direct sunlight to mitigate the effects of global warming. Claims such as these are often referred to as “chemtrails”. Contrary to these claims, atmospheric chemists and geochemists agree that there is no scientific evidence of “chemtrails”, “covert geoengineering”, or a secret large-scale atmospheric program to mitigate climate change[1]. Aircraft engines produce condensation trails, or contrails, as hot, humid exhaust mixes with the atmosphere at altitudes of 8 – 13 km. Specifically, water vapor from the jet exhaust condenses and may freeze at high altitudes, where there is a lower vapor pressure and temperature than the exhaust. As described in a Scientific American article, “this mixing process forms a cloud very similar to the one your hot breath makes on a cold day”. A 2018 study provides additional details about the process of contrail formation, “Depending on surrounding atmospheric conditions, contrails can be short- or long-lived. Long-lived contrails are those that remain for at least 10 min—defined by the World Meteorological Organization as Cirrus homogenitus—and are the only man-made type of ice clouds”.[2] As Doug MacMartin notes below, contrails are essentially artificial cirrus clouds, which are wispy, hair-like clouds found at high altitudes. The video also claims that Solar Radiation Management (SRM) “has and is causing catastrophic damage to the planet’s life support systems”. SRM, or solar geoengineering, describes hypothetical strategies to combat global warming by reflecting sunlight away from the Earth. “Possible methods include reducing heat-trapping clouds, sending a giant sunshade up into orbit or releasing aerosols into the stratosphere,” according to a Carbon Brief article. While some studies suggest that SRM could negatively impact biodiversity, which subsequently affects human health, others find that some of the risks of solar geoengineering can be minimized[3,4]. Currently, conversations about SRM strategies, or albedo modification, are purely theoretical. “We are confident that there is no currently active program to actually test or implement albedo modification outdoors,” wrote David Keath. Therefore, the video’s claims that SRM is happening and causing catastrophic damage are also incorrect. Scientists’ Feedback: Douglas MacMartin Senior Research Associate, Cornell University: All of these claims are pure fantasy. The alternative hypothesis to their supposed conspiracy (which would require cooperation from hundreds of thousands of people in every single country on the planet) is the rather mundane belief that clouds are made of water, and since jet fuel is hydrocarbon, burning it produces water vapour as well as cloud condensation nuclei, and thus produces contrails; basically an artificial cirrus. The SRM for global warming mitigation would involve putting things like sulfate (which wouldn’t leave trails) much higher into the atmosphere than any current aircraft can fly. If that was being done, it would be trivially detectable from satellite observations. We also know with 100% certainty that (a) the aircraft contrails they see aren’t geoengineering, and (b) no-one is doing geoengineering."
https://science.feedback.org/review/destruction-of-the-amazon-forest-very-likely-contributes-to-global-warming-as-accurately-described-in-the-national-geographic-article/,1,"National Geographic, by Craig Welch, on 2021-03-11.",,"""First study of all Amazon greenhouse gases suggests the damaged forest is now worsening climate change""",,,,1 – Covey et al. (2021). Carbon and Beyond: The Biogeochemistry of Climate in a Rapidly Changing Amazon. Frontiers in Forests and Global Change. 2 – Baccini et al. (2017). Tropical forests are a net carbon source based on aboveground measurement of gain and loss. Science. 3 – Zemp et al. (2017). Self-amplified Amazon forest loss due to vegetation-atmosphere feedbacks. Nature Communications. 4 – Scott et al. (2018). Impact on short-lived climate forcers increases projected warming due to deforestation. Nature Communications. 5 – Hubau et al. (2020). Asynchronous carbon sink saturation in African and Amazonian tropical forests. Nature. 6 – Nobre et al. (2016). Land-use and climate change risks in the Amazon and the need of a novel sustainable development paradigm. PNAS. 7- Lovejoy and Nobre (2018). Amazon tipping point. Science Advances. ,"Reviewers’ Overall Feedback: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. The article is good overall, although there are two small issues. First, the title seems to overestimate the results. The scientific study the National Geographic article is based on cannot account for all of the climate forcers, as there are no Amazon basin wide estimates (as clearly stated in the study). This drawback could potentially change the overall warming effect, and therefore the title seems to exaggerate. However, it is true that to look at the climatic effect of the Amazonian rain forest, one should not only look at CO2. Second, when the article says the moisture respired by plants falls as rain again, one should say only 50% falls as rain again, according to Zemp et al. (2017)[3]. When the article says: “But until recently, no one had attempted to understand that balance”, I’m not sure if the author is claiming that the study authors are the only ones who assessed this balance, as Scott et al., 2018 conducted the first global approach taking into account Amazonia[4]. Richard Houghton Senior Scientist Emeritus, Woodwell Climate Research Center: Even considering CO2 alone, the Amazon basin is likely a carbon source rather than a sink, according to Baccini et al. (2017)[2]. Based on satellite-measurement of carbon stocks, we could already conclude that the forests of Brazil and Latin America were losing more carbon than they were accumulating. However, the Baccini et al. study did not specifically quantify Amazonian forests, and did not consider other greenhouse gases. The main contribution of this new study is that the forests of the Amazon basin are adding to climate change, not helping to slow it. And the conclusion is based on a comprehensive analysis of several greenhouse gases. Overall this is an informative article, for the most part accurately reporting the findings of a recent review[1]. However, the original headline and photo caption (since updated) suggested that the Amazon is “no longer storing carbon for our planet” – which is inaccurate given the 150-200 billion tonnes of carbon the rainforest is still estimated to store and recent observations showing that in most years carbon storage in undisturbed areas is for the moment still growing (Hubau et al., 2020)[5]. The headline and caption also didn’t initially make it clear enough that the higher emissions are primarily driven by human disturbance rather than natural feedbacks to climate change. The difference between disturbance-driven emissions and natural feedbacks is an important point to be clear on because several steadily worse milestones – a net warming feedback from across the whole Amazon due to direct human disturbances, undisturbed areas transitioning from carbon sinks to sources due to climate change, and a deforestation or warming-induced ‘tipping point’ beyond which a large-scale regime shift to savannah becomes inevitable – are often conflated in popular discussion of climate change and the Amazon rainforest. While this review suggests the former may be close or passed, undisturbed rainforest may take another couple of decades to become a persistent carbon source[5] and the ‘dieback’ tipping point could occur beyond 20-40% deforestation (vs. ~17% now) or ~4°C of global warming[6,7]. If the Amazon had become a net warming forcing, but this was still human-driven, then this means this may still be reversible by mitigating disturbance, whereas a transition to net positive feedbacks from undisturbed rainforest would not be easily reversible. Although the increased focus on non-carbon dioxide forcings in the Amazon is welcome, it is also not mentioned in this article that part of the reason for the mainstream focus on carbon is that other forcing agents, such as methane, tend to be quite short-lived, reducing their long-term effect and making carbon storage the dominant factor for long-term climate change. There is some debate too over the ideal timescale and accounting method for comparing the contribution of short-lived climate forcers to carbon dioxide, but in contrast to the study, the article does not get into the issue of timescales and how it could affect the study’s conclusion. As a result, the article still lacks some extra context on forcing timescales and why some other climate scientists might disagree with the overall conclusion on this basis. The updated article does a good job overall though at conveying the uncertainties discussed in the review, making it clear that net warming due to the Amazon is not yet confirmed, and also illustrates the Amazon’s biogeochemical complexity and the many ways it can interact with climate change."
https://science.feedback.org/review/atlantic-ocean-circulation-system-is-slowing-down-as-accurately-described-in-the-new-york-times-article/,1.5,"The New York Times, by Jeremy White, Moises Velasquez-Manoff, on 2021-03-02.",,"""In the Atlantic Ocean, Subtle Shifts Hint at Dramatic Dangers""",,,,"1 – Caesar et al. (2021) Current Atlantic Meridional Overturning Circulation weakest in last millennium. Nature Geoscience. 2 – Duchez et al. (2016) Drivers of exceptionally cold North Atlantic Ocean temperatures and their link to the 2015 European heat wave. Environmental Research Letters. 3 – Josey et al. (2017) The Recent Atlantic Cold Anomaly: Causes, Consequences, and Related Phenomena. Annual Review of Marine Science. 4 – Rahmstorf et al. (2015) Exceptional twentieth-century slowdown in Atlantic Ocean overturning circulation. Nature Climate Change. 5 – Caesar et al. (2018) Observed fingerprint of a weakening Atlantic Ocean overturning circulation. Nature. 6 – Collins et al. (2019) Extremes, Abrupt Changes and Managing Risk. In: IPCC Special Report on the Ocean and Cryosphere in a Changing Climate.","Reviewers’ Overall Feedback: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. This article is well-written, and the visuals are outstanding. It is a very strong piece of science communication. That being said, there is at least one error. The author mistakenly conflates the long-term warming hole with the shorter-term North Atlantic cold anomaly. The two phenomena have very different timescales and are likely driven by different mechanisms. The long-term warming hole that is the focus of the NYT article may have been driven by the Atlantic Meridional Overturning Circulation (AMOC) slowdown as discussed, but the 2015 cold anomaly that was linked to European heat waves was a shorter-term phenomena that was likely caused by successive winters with extreme heat loss, as opposed to an AMOC slowdown. Indeed, in the study by Duchez et al. that was linked to in the NYT article, the authors state “It is important to distinguish between this long-term warming hole and the short term 2015 cold anomaly that is the focus of our study.”[2] Unfortunately, the authors of the NYT article missed this distinction and conflated the two phenomena. To be fair, this is an easy mistake to make! Many of our own colleagues have confused the two phenomena at first glance. For more information on the causes of the recent, short-term North Atlantic cold anomaly, see this review article[3]. Marcos Fontela Postdoctoral researcher, Institute of Marine Research (IIM-CSIC): It is a very powerful and insightful article. The article has awesome graphics and good selection of quotes, although it would be very nice to have the comments from the lead author of the article (L. Caesar). The article has very good, up-to-date references. Some minor comments: 1) As was already pointed by Dan Jones on twitter, they mixed the decadal-scale cold blob and the short-term subpolar North Atlantic 2015 cold anomaly. 2) In the article sometimes the distinction between the Gulf Stream and AMOC is not very clear. It’s true that sometimes the AMOC is called the Gulf Stream System, but because the AMOC is a network of currents, we should keep in mind that Gulf Stream and AMOC are not synonyms. There are more currents in the AMOC and they are not only in the surface-subsurface layer. Stefan Rahmstorf Professor, Potsdam University: The article provides a very good and credible overview of recent scientific findings regarding the Atlantic Meridional Overturning Circulation (AMOC) and nicely covers science history all the way back to discoveries in the 16th Century. It properly describes the relationship between Gulf Stream and AMOC, and it uses beautiful visualisations. One minor comment, it describes our recent study as providing “reconstructions of sea temperature around the North Atlantic, some going back 1,600 years”, whilst what we mostly provided are proxy data series for AMOC strength from the sediments at the bottom of the Atlantic, most of which are unrelated to temperature. But that is just one sentence in an otherwise great article. Generally speaking, the article is sound and has numerous sources of scientists to equilibrate the debate. There are only a few things that are maybe exaggerated and not clearly explained in my opinion, e.g.: The estimate that the AMOC has weakened by 15% is not in Rahmstorf et al. (2015)[4], but in Caesar et al. (2018)[5]. Also, the sentence “Hurricanes derive their energy from heat in the water” is a bit misleading when referring to mid-latitude storms. The fact that a weakening AMOC might enhance their probability is mainly due to strengthening of equator-pole temperature gradient. Consensus is low on the paper cited in the article. Why not refer to the IPCC chapter 6.7 special report on extremes, abrupt changes, and managing risks in the ocean and cryosphere in a changing climate instead to find consensus on potential climatic impacts?[6] Annotations: The statements quoted below are from the article; comments are from the reviewers (and are lightly edited for clarity). “Scientists at the U.K.’s National Oceanography Centre have somewhat counterintuitively linked the cold blob in the North Atlantic with summer heat waves in Europe. In 2015 and 2018, the jet stream, a river of wind that moves from west to east over temperate latitudes in the northern hemisphere, made an unusual detour to the south around the cold blob. The wrinkle in atmospheric flow brought hotter-than-usual air into Europe, they contend, breaking temperature records.” Here, the decadal-scale warming hole that is possibly linked to AMOC slowdown has been conflated with the shorter-term cold anomaly that featured record low North Atlantic sea surface temperatures in 2015. The authors of the U.K.’s National Oceanography Centre study are careful to make this distinction in their article: “It is important to distinguish between this long-term warming hole and the short-term 2015 cold anomaly that is the focus of our study.”[2] The long-term warming hole that is the focus of this New York Times article is not the same thing as the short-term 2015 cold anomaly. The two phenomena have very different timescales and different causes. Current understanding suggests that the short-term 2015 cold anomaly was caused by successive winters with extreme heat loss, i.e. it was largely driven by changes in air-sea heat exchange. The longer-term warming hole may have been caused by the AMOC slowdown, as discussed in this article. For more information on the 2015 cold anomaly and its causes, see this review article led by Simon Josey[3]. ““That was not predicted,” said Joel Hirschi, principal scientist at the centre and senior author of the research. It highlights how current seasonal forecasting models are unable to predict these warm summers. And it underscores the paradox that, far from ushering in a frigid future for, say, Paris, a cooler North Atlantic might actually make France’s summers more like Morocco’s.” As in the paragraph above, here the long-term warming hole has been conflated with the short-term North Atlantic cold anomaly, which are phenomena with very different timescales and causes. Predicting future short-term North Atlantic cold anomalies and subsequent possible heat waves would be done using seasonal forecasting models. Predicting the longer-term impacts of an AMOC slowdown would be done using climate models run under different emissions scenarios. Conflating the two mechanisms and timescales has resulted in some confusion in this part of the article."
https://science.feedback.org/review/scientists-didnt-announce-impending-environmental-catastrophes-every-decade-since-the-1970s/,Inaccurate,"Facebook, Facebook users, 2021-02-20","Science said in the: 70s, another ice age in 10 years; 80s, acid rain will destroy all crops in 10 years; 90s: the ozone layer will be destroyed in 10 years; 2000’s the ice caps will be gone on 10 years",,"Factually inaccurate: Over the past few decades, scientists have studied and discussed major environmental concerns, such as acid rain, ozone layer destruction, and melting ice caps. However, the majority of scientists didn’t claim that these environmental issues would cause drastic, short-term catastrophes, such as the destruction of all crops in ten years. Misrepresent sources: The claim misrepresents the perspective of most scientists on these environmental issues. Specifically, a few of the alleged consequences of these environmental issues stemmed from a small number of scientists, or would take far longer than a decade to occur.","Over the past century, scientists have studied climate change, acid rain, ozone layer depletion, and melting ice caps, as well as other environmental issues. Scientific understanding of the mechanism behind these events and their potential consequences has increased significantly through observational studies, experiments, and model simulations. Early warnings related to these environmental issues led to national and international regulations aimed at mitigating them, such as acid rain, ozone depletion, and climate warming.",”Government funded science: 70’s: another ice age in 10 years; 80’s: acid rain will destroy all crops in 10 years; 90’s: the ozone layer will be destroyed in 10 years; 2000’s the ice caps will be gone on 10 years”,"1 – Peterson et al. (2012). The myth of the 1970s global cooling scientific consensus. Bulletin of the American Meteorology Society. 2 – Rasool and Schneider (1971). Atmospheric Carbon Dioxide and Aerosols: Effects of Large Increases on Global Climate. Science. 3 – Charney et al. (1979). Carbon dioxide and climate : a scientific assessment. National Academy of Science. 4 – Sherwood et al. (2020). An Assessment of Earth’s Climate Sensitivity Using Multiple Lines of Evidence. Reviews of Geophysics. 5 – O’Neill (1988) Acid Rain: A Selective Bibliography. California Polytechnic State University. 6 – Irving (1990) NAPAP Acid Rain Conference improves scientific consensus, discounts extremes. EOS. 7 – National Acid Precipitation Assessment Program (1991) Acidic deposition: state of science an technology. 8 – Irving (1983) Acidic Precipitation Effects on Crops: A Review and Analysis of Research. Journal of environmental quality. 9 – Barse et al. (1985) Effect of air pollution and acid rain on agriculture: an annotated bibliography. United State Department of Agriculture. 10 – United State Environmental Protection Agency (2020) The Legacy of EPA’s Acid Rain Research. 11 – WMO/UNEP (1994) Scientific Assessment of Ozone Depletion. 12 – Prather et al. (1990) Global impact of the Antarctic ozone hole: Dynamical dilution with a three‐dimensional chemical transport model. Journal of Geophysical Research – Atmospheres. 13 – Prather et al. (1996) The ozone layer: The road not taken. Nature. 14 – Newman et al. (2009). What would have happened to the ozone layer if chlorofluorocarbons (CFCs) had not been regulated? Atmospheric Chemistry and Physics. 15 – IPCC (2001) Climate Change 2001: Synthesis Report. 16 – IPCC (2007) Climate Change 2007: Synthesis Report. 17 – Velicogna (2009) Increasing rates of ice mass loss from the Greenland and Antarctic ice sheets revealed by GRACE. Geophysical Research Letters – The Cryosphere.","Review: The claim that government funded scientists have announced catastrophic short-term environmental effects every decade since the 1970s have been repeated in hundreds of Facebook posts such as this one. In the 1970s, the majority of climate studies projected global warming The claim that scientists announced a forthcoming ice age in the 1970s is a popular myth frequently used by those who want to cast doubt on what climate scientists say today about global warming. However, as stated in Peterson et al. (2008), “a review of the climate science literature from 1965 to 1979 shows this myth to be false. The myth’s basis lies in a selective reading of the texts both by members of the media at the time and by some observers today. In fact, emphasis on greenhouse warming dominated the scientific literature even then”.[1] Only a few scientific studies predicted global cooling. For instance, in the often-cited Rasool and Schneider (1971) paper, the authors simulated the cooling effect of aerosols (suspended particles in the air) if their concentration were to increase significantly in the future[2]. However, it’s incorrect to claim there was a scientific consensus predicting global cooling and an imminent ice age. On the contrary, by the end of the 1970s scientists agreed that greenhouse gases were the dominant forcing of the global climate changes happening currently[1]. The few ice-age predictions were abandoned shortly thereafter. Furthermore, actions taken since the 1970s to reduce aerosol emissions resulting from industrial activity have strongly limited the cooling effect of aerosols on the climate. Contrary to the claim’s suggestions, observed global warming patterns are well-aligned with most of the predictions made by scientists in the 1970s. In its 1979 report, the U.S. National Academy of Sciences concluded, “when it is assumed that the CO2 content of the atmosphere is doubled and statistical thermal equilibrium is achieved, the more realistic of the modeling efforts predict a global surface warming of between 2°C and 3.5°C, with greater increases at high latitudes”.[3] This is in close agreement with the latest estimation of Earth’s climate sensitivity, ranging 2.6-3.9°C[4]. In conclusion, the claim emphasizes a prediction from a minority of studies and neglects the scientific consensus that emerged in the 1970s on the role of greenhouse gasses as a major driver of global warming. In the 1980s, scientists thought acid rain contributed to lake acidification and forest dieback The claim that scientists projected the destruction of all crops within ten years due to acid rain is a misinterpretation of the scientific debate that occurred in the early 1980s. At the time, acid rain caused by nitrogen dioxide (NO2) and sulfur dioxide (SO2) emissions from coal power electricity plants and other sources was a major environmental concern. Scientists hypothesized that these emissions were responsible for lake acidification and the dying of forests in Europe and North America, resulting in numerous studies on the topic[5]. The U.S. National Acid Precipitation Assessment Program (NAPAP) was launched in 1980 to guide national debate on clean-air legislation. Researchers spent a decade studying atmospheric deposition and its effects on aquatic and terrestrial ecosystems. Irving (1990) explained, “when NAPAP was initiated in 1981, scientific opinion on acid rain was divided. The issue was viewed by some as a rapidly intensifying disaster requiring immediate remediation, and by others as a speculative hypothesis without sufficient substantiation. Most scientific opinion now lies well inside both of these two positions”[6]. The first NAPAP report concluded that acid rain damaged certain lakes and streams in the eastern United States and Canada, and contributed to the decline of high-elevation red-spruce forests[7]. Contrary to the claim, scientists didn’t project that all crops would be destroyed by acid rain within ten years. In a paper published in 1983, Irving indicated that an “analysis of the current literature concludes that the effects of acidic precipitation on crops appear to be minimal and that when responses are observed, they may be positive or negative”[8]. A couple of years later, a report from the U.S. Department of Agriculture reached the same conclusion, “acid rain seems to be far less damaging to agriculture (if damaging at all) than the gaseous pollutants”[9]. Gaseous pollutants, such as SO2 and NO2, and acid rain originate from similar sources: man’s pollutant emissions into the atmosphere. Adoption of policies like the Clean Air Act in the U.S., and the Geneva Convention on Long-Range Transboundary Air Pollution in Europe led to a drastic reduction of industrial SO2 and NO2 emissions, mitigating the effects of acid rain. For example, average annual ambient concentrations of SO2 decreased 93% between 1980 and 2018 in the U.S.[10]. In conclusion, the claim is misleading and doesn’t reflect the research and scientific discussions about acid rain that occurred in the 1980s. In the 1990s, the ozone layer over the Antarctic was thinning dramatically in spring The claim that scientists said the ozone layer would be destroyed in ten years is an exaggeration related to the discovery of the ozone hole. In the early 1980s, ground-based and satellite measurements revealed that the stratospheric ozone layer was thinning over the South Pole every spring. The reduction in ozone concentration was coined “ozone hole” metaphorically. The hole refers to the area in which ozone concentrations drop below the historical threshold of 220 Dobson Units. This observation raised concerns because stratospheric ozone protects Earth’s surface from the Sun’s harmful ultraviolet radiation. From 1980 through the early 1990s, the ozone hole rapidly grew in area and depth, with ozone depletion of up to 60%. Contrary to the claim, the ozone hole is essentially a seasonal, regional-scale phenomenon in the Antarctic, although anomalous ozone decreases of about 4 – 5% per decade were also observed in the midlatitudes of both hemispheres[11]. In 1990, a simulation study showed that “as the vortex breaks down and the ozone hole is dispersed, significant depletions to column ozone, of order 10 Dobson units (3%) occur as far north as 40°S during austral summer”[12] . This study also concluded that 70% of the initially prescribed ozone deficit is replenished through stratospheric chemistry by the end of the year. A global and abrupt destruction of the ozone layer was, however, not projected in ten years. During the 1980s, scientists discovered that human-made chemicals, such as chlorofluorocarbons (CFCs, used in refrigerators and aerosol spray), facilitated the destruction of the ozone layer. The global recognition of the destructive potential of CFCs led to the 1987 Montreal Protocol, a treaty that phased out the production of ozone-depleting chemicals. As a result, annual ozone holes roughly stabilized in the early 21st century. A lack of action would have led to severe ozone depletion, with increased levels of solar UV radiation levels at the Earth’s surface. Prather et al. (1996) modeled the ozone response to continued growth of the ozone-depleting substances without the Montreal Protocol, and calculated a globally-averaged total ozone depletion of 10% by 1999[13]. A more complex simulation estimates that in the absence of regulation, 17% of the globally-averaged column ozone would have been destroyed by 2020, and 67% by 2065, in comparison to 1980[14]. Also, “large ozone depletions in the polar region become year round rather than just seasonal as is currently observed in the Antarctic ozone hole”. When taking into account the impact of the Montreal Protocol, the authors predicted that the ozone layer would recover by 2050-2060[14]. In conclusion, the claim is incorrect based on observations of the ozone hole and the projections made about ozone depletion in the 1990s. In the 2000s, studies projected that polar ice caps could melt over millennia The claim that scientists projected the imminent melting of ice caps is an overstatement that does not reflect current research or scientific understanding. The fate of the Arctic and Antarctic ice sheets is the subject of numerous observational studies and simulation research because of their contributions to sea-level rise. Unlike ice caps, sea ice does not raise sea-level when it melts, but has declined dramatically in the Arctic. In addition, the poles are warming at a rate nearly three times faster than the global average. Due to different geographical settings, the Arctic and Antarctic ice sheets respond differently to the rise in global temperatures. In 2001, the Intergovernmental Panel on Climate Change (IPCC) third assessment report concluded, “The Antarctic ice sheet as a whole is likely to increase in mass during the 21st century. However, the West Antarctic ice sheet could lose mass over the next 1,000 years with an associated sea-level rise of several meters”[15]. In contrast, the report stated, the Greenland ice sheet is likely to lose mass during the 21st century and contribute a few centimeters to sea-level rise. Scientists projected more significant losses in ice sheet mass over millennial time scales, as the ice sheets continue reacting in response to climate warming. As stated in the IPCC report, “Ice sheet models project that a local warming of larger than 3°C, if sustained for millennia, would lead to virtually a complete melting of the Greenland ice sheet with a resulting sea-level rise of about 7 meters”. Authors of the IPCC report acknowledged an incomplete understanding of some of the underlying processes. Based on more recent observations, the 2007 IPCC report concluded that the risk of additional contributions to sea-level rise from both the Greenland and possibly Antarctic ice sheets “may be larger than projected by ice sheet models and could occur on century time scales”[16]. At the time, polar ice sheets were shown to be losing mass at an accelerating rate by the end of the 2000s[17]. In conclusion, the claim is incorrect, as the possibility of an abrupt melting of ice caps wasn’t considered in the 2000s."
https://science.feedback.org/review/the-scientific-research-facility-haarp-cannot-create-natural-disasters-or-influence-human-thoughts-and-movements-contrary-to-online-claims/,Incorrect,"Gaia, Anonymous, 2020-12-11","HAARP may deliberately create destruction on a global scale, causing earthquakes, cyclones, flooding, snowstorms, around the world; HAARP may be attacking the citizens of the world telepathically, influencing thoughts with low frequency vibrations",,"Incorrect: The Gaia article leaves the reader with an extremely poor understanding of how the High-frequency Active Auroral Research Program (HAARP) works. The facility is a high-frequency (shortwave radio) transmitter and doesn’t transmit low-frequency vibrations, as stated in the Gaia article. HAARP analyzes physics phenomena in the uppermost part of the atmosphere (known as the ionosphere) by studying the small heating effects the transmitter creates there that last for only a few seconds. Thus, it cannot affect human thought processes or movements in any way. Inadequate support: There is no scientific evidence provided to support the claims made in the Gaia article about HAARP’s ability to cause natural disasters or control human behaviors. The Gaia article cited an article by the U.K. tabloid The Express and another Gaia article as supporting evidence for the natural disasters claim, but these are not scientific or peer-reviewed sources. The claim that HAARP can control minds is purportedly supported by a “leaked classified government file”, but the article provided no direct link or reference to this file. ","The High-frequency Active Auroral Research Program (HAARP) is a research facility that uses a high-power, high-frequency transmitter to study the physical properties and behaviour of the highest point of the atmosphere, the ionosphere. One example of natural phenomena that HAARP studies is the aurora borealis, also known as the northern lights. Radio transmissions from HAARP only cause small effects in the ionosphere that last for a brief span of a few seconds. There is no evidence that HAARP can cause natural disasters or influence with human movements and thoughts.","The HAARP organization may deliberately create destruction on a global scale, causing earthquakes, cyclones, flooding, snowstorms, and other disasters, around the world; The HAARP facility may be attacking the citizens of the world telepathically, influencing thoughts with low frequency vibrations; ""it is possible to control human movements, glandular functions, and specific mental manifestations using electromagnetic stimulation.""","1 – McCoy et al. (2018) Haarp, a Powerful Active Ionospheric Laboratory Open for International Research. 42nd COSPAR Scientific Assembly. 14-22 July 2018, Pasadena, California, USA 2 – Todd Pedersen (2015) HAARP, the most powerful ionosphere heater on Earth. Physics Today. 3 – Inan et al. (2004) Multi‐hop whistler‐mode ELF/VLF signals and triggered emissions excited by the HAARP HF heater. Geophysical Research Letters. 4 – Piddyachiy et al. (2011) DEMETER observations of the ionospheric trough over HAARP in relation to HF heating experiments. Journal of Geophysical Research: Space Physics","Review: The claim appeared in an article published by Gaia in mid-December 2020, receiving more than 16,000 interactions on Facebook according to the social media analytics tool Crowdtangle. The High-frequency Active Auroral Research Program (HAARP) is a research facility operated by the University of Alaska Fairbanks[1]. It transmits high-frequency radio signals into the highest point of the atmosphere, the ionosphere, using 360 radio transmitters and 180 antennas. The facility covers about 14 hectares (0.14 kilometers squared) near the town of Gakona, Alaska, which is about 250 kilometers northeast of Anchorage, Alaska’s largest city. The radio signals are partially absorbed between 100 kilometers and 350 kilometers in altitude, accelerating electrons in the ionosphere and briefly “heating” it up[2]. By analyzing how radio waves interact with electrons in the ionosphere[3,4], researchers at HAARP are able to study phenomena, such as the effects of the aurora borealis, or northern lights, on radio systems and aircraft communications at high altitudes. HAARP has previously been the subject of conspiracy theories, but “claims in the Gaia article about HAARP’s ability to cause natural disasters or control human behaviors are false,” said Robert McCoy, director of the Geophysical Institution at the University of Alaska Fairbanks. “HAARP is a high-frequency transmitter (basically a shortwave radio),” he explained. “It is used to conduct experiments on a 100 x 100 kilometer patch of the overhead ionosphere. Transmissions from HAARP only cause small effects in the ionosphere that last a few seconds. In addition, the facility is operated only a few hours each year. The amount of high-frequency energy coming from amateur radio operators around the world almost certainly exceeds transmissions from HAARP. HAARP cannot affect any of the natural phenomena mentioned in the article, such as earthquakes and snowstorms, and there is no way it can interact with humans or influence them.” HAARP produces only small heating effects in the ionosphere. It therefore cannot influence natural phenomena like cyclones or hurricanes, which occur in the much lower-altitude (7 kilometer) troposphere and generate orders of magnitude more energy. In a 2018 U.S. News article, McCoy said that HAARP is “not a weapon, and it couldn’t be”. “The way high-frequency radios work is that the atmosphere is transparent to those signals. If we made this (facility) 10 times bigger and tried, we still couldn’t affect the weather. Minds? Electrical signals in the mind are very low-frequency. HAARP is very large-frequency; the waves are meters-long. So there’s no way they could control minds,” he explained. Former HAARP Chief Scientist Chris Fallen said in a 2017 news article published on the University of Alaska Fairbanks website that HAARP attracts more attention than the average scientific research facility, likely because of its focus on an obscure area of the atmosphere called the ionosphere. This has led to misunderstandings about the purpose of the HAARP facility, he explained. “HAARP cannot control the weather, contrary to one conspiracy theory. It has too little power and affects a different part of the atmosphere. Neither can it manipulate our brains, as alleged by another theory. Generally, space physicists focus on regions more than 60 miles (nearly 97 kilometers) above our heads, where HAARP’s radio waves are 100 times weaker than those from mobile phones.” Scientists’ Feedback: Robert McCoy Director, Geophysical Institute, University of Alaska:HAARP has previously been the subject of conspiracy theories, but claims in the Gaia article about HAARP’s ability to cause natural disasters or control human behaviors are false. HAARP is a high-frequency transmitter (basically a shortwave radio). It is used to conduct experiments on a 100 x 100 kilometer patch of the overhead ionosphere. Transmissions from HAARP only cause small effects in the ionosphere that last a few seconds. In addition, the facility is operated only a few hours each year. The amount of high-frequency energy coming from amateur radio operators around the world almost certainly exceeds transmissions from HAARP. HAARP cannot affect any of the natural phenomena mentioned in the article, such as earthquakes and snowstorms, and there is no way it can interact with humans or influence them. READ MORE Learn more about this topic by reading this post by the University of Alaska Fairbanks"
https://science.feedback.org/review/breitbart-article-makes-numerous-false-claims-about-the-impacts-of-climate-change-based-on-global-warming-policy-foundation-post-delingpole-goklany/,-2,"Breitbart, by James Delingpole, Indur Goklany, on 2021-02-07.",,"""Study Disputes That Earth Is in a ‘Climate Emergency’""",,,,"1 – IPCC (2014) Climate Change 2014: Summary: for Policymakers. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. 2 – National Academies of Sciences, Engineering, and Medicine (2016) Attribution of extreme weather events in the context of climate change. The National Academies Press. 3 – Swain et al. (2020) Attributing extreme events to climate change: A new frontier in a warming world. One Earth. 4 – Knutson et al. (2020) Tropical Cyclones and Climate Change Assessment: Part II: Projected Response to Anthropogenic Warming. Bulletin of the American Meteorological Society. 5 – Liu et al. (2019) Causes of large projected increases in hurricane precipitation rates with global warming. npj Climate and Atmospheric Science. 6 – Allamano et al. (2009) Global warming increases flood risk in mountainous areas. Hydrology and Land Surface Studies. 7 – Franzke et al. (2020) Risk of extreme high fatalities due to weather and climate hazards and its connection to large-scale climate variability. Climatic Change. 8 – Gonzalez et al. (2018) Chapter 25: Southwest. In Impacts, Risks, and Adaptation in the United States: Fourth National Climate Assessment, Volume II. 9 – Nabuurs et al. (2013) First signs of carbon sink saturation in European forest biomass. Nature Climate Change. 10 – De Graaff et al. (2006) Interactions between plant growth and soil nutrient cycling under elevated CO2: a meta-analysis. Global Change Biology. 11 – Mbow et al. (2019) IP Food Security. In: Climate Change and Land: an IPCC special report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems. IPCC report. 12 – Moore et al. (2017) New science of climate change impacts on agriculture implies higher social cost of carbon. Nature. 13 – Moore and Lobell (2015) The fingerprint of climate trends on European crop yields. PNAS. 14 – Diffenbaugh (2020) Verification of extreme event attribution: Using out-of-sample observations to assess changes in probabilities of unprecedented events. Science Advances. 15 – Swain et al. (2020) Attributing Extreme Events to Climate Change: A New Frontier in a Warming World. One Earth. 16 – Haque et al. (2012) Reduced death rates from cyclones in Bangladesh: what more needs to be done? Bulletin of the World Health Organization 17 – Kossin et al. (2020) Global increase in major tropical cyclone exceedance probability over the past four decades. PNAS. 18 – Vohra et al. (2011) Global mortality from outdoor fine particle pollution generated by fossil fuel combustion: Results from GEOS-Chem. Environmental Research. 19 – Zhang et al. (2019) Ozone Pollution: A Major Health Hazard Worldwide. Frontiers in Immunology. 20 – Patz et al. (2005) Impact of regional climate change on human health. Nature. 21 – Mitchell et al. (2016) Attributing human mortality during extreme heat waves to anthropogenic climate change. Environmental Research Letters. 22 – Gensini & Brooks (2018) Spatial trends in United States tornado frequency. npj Climate and Atmospheric Science. 23 – Elsner et al. (2018) Increasingly Powerful Tornadoes in the United States. Geophysical Research Letters. 24 – Diffenbaugh et al. (2013) Robust increases in severe thunderstorm environments in response to greenhouse forcing. PNAS. 25 – Hoogewind et al. (2017) The Impact of Climate Change on Hazardous Convective Weather in the United States: Insight from High-Resolution Dynamical Downscaling. Journal of Climate. 26 – Marvel et al. (2019) Twentieth-century hydroclimate changes consistent with human influence. Nature. 27 – Diffenbaugh et al. (2015) Anthropogenic warming has increased drought risk in California. PNAS. 28 – Williams et al. (2020) Large contribution from anthropogenic warming to an emerging North American megadrought. Science. 29 – Abatzoglou and Williams (2016) Impact of anthropogenic climate change on wildfire across western US forests. PNAS. 30 – Williams et al. (2019) Observed Impacts of Anthropogenic Climate Change on Wildfire in California. Earth’s Future. 31 – Goss et al. (2020) Climate change is increasing the likelihood of extreme autumn wildfire conditions across California. Environmental Research Letters. 32 – Abram et al. (2021) Connections of climate change and variability to large and extreme forest fires in southeast Australia. Communications Earth & Environment. 33 – Feurdean et al. (2020) Recent fire regime in the southern boreal forests of western Siberia is unprecedented in the last five millennia. Quaternary Science Reviews. 34 – Jones et al. (2020) Climate Change Increases the Risk of Wildfires. ScienceBrief Review. 35 – Bowman et al. (2020) Vegetation fires in the Anthropocene. Nature Reviews Earth & Environment. 36 – Doerr and Santín (2016) Global trends in wildfire and its impacts: perceptions versus realities in a changing world. Philosophical Transactions of the Royal Society B. 37 – Beillouin et al. (2020) Impact of extreme weather conditions on European crop production in 2018. Philosophical Transactions of the Royal Society B. 38 – Tigchelaar et al. (2018) Future warming increases probability of globally synchronized maize production shocks. PNAS. 39 – Mehrabi and Ramankutty (2019) Synchronized failure of global crop production. Nature Ecology & Evolution. 40 – Chatzopoulos et al. (2020) Climate extremes and agricultural commodity markets: A global economic analysis of regionally simulated events. Weather and Climate Extremes. 41 – Hall et al. (2014) Understanding flood regime changes in Europe: a state-of-the-art assessment. Hydrol. Earth Syst. Sci. 42 – Murphy et al. (2013) Climate-driven trends in mean and high flows from a network of reference stations in Ireland. Hydrological Sciences Journal. 43 – Birsan et al. (2005) Streamflow trends in Switzerland. Journal of Hydrology. 44 – Solin (2008) Analysis of floods occurrence in Slovakia in the period 1996–2006. J. Hydrol. Hydromech. 45 – Vormoor et al. (2015) Climate change impacts on the seasonality and generation processes of floods – projections and uncertainties for catchments with mixed snowmelt/rainfall regimes. Hydrol. Earth Syst. Sci. 46 – Lawrence and Hisdal (2011) Hydrological projections for floods in Norway under a future climate. 47 – Pall et al. (2019) A Climatology of Rain-on-Snow Events for Norway. Journal of Climate. 48 – Madsen et al. (2014) Review of trend analysis and climate change projections of extreme precipitation and floods in Europe. Journal of Hydrology. 49 – Nerem et al. (2018) Climate-change–driven accelerated sea-level rise detected in the altimeter era. PNAS. 50 – Bamber et al. (2019) Ice sheet contributions to future sea-level rise from structured expert judgment. PNAS.","Reviewers’ Overall Feedback: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. This article uses a single poorly-sourced, non-peer reviewed report as a basis for making numerous misleading and in multiple instances demonstrably false claims regarding climate change and its global implications. Kerry Emanuel Professor of Atmospheric Science, MIT: The article is mostly inaccurate and uniformly misleading. For example, in declaring that hurricane frequency is not increasing, it neglects to mention that there was never a consensus prediction that the frequency of all hurricanes would increase, or in stating that weather-related deaths are decreasing fails to mention that the reasons for that have nothing to do with climate change but rather with rapidly improving warnings and preparedness. This is a biased and purposely misleading article that contradicts evidence-based scientific literature. The authors did not care to cross-check the claims made by Mr. Goklany nor to set them in the broader context of the scientific evidence about climate change and impacts (e.g. IPCC reports)[1]. The article’s scientific credibility is very low. The author cherry-picks data, makes broad generalizations and characterizations based on incomplete or flimsy reasoning, and repeatedly misinterprets technological and economic progress in justifying false claims and misinformation minimizing global warming impacts. Annotations: The statements quoted below are from the article; comments are from the reviewers (and are lightly edited for clarity). “according to a study for the Global Warming Policy Foundation” It is important to note that the purported “study” that is the subject of this article is not actually a study in any meaningful sense of the word. It is written by a single author who is not a physical or climate scientist, contains no previously unpublished data, and has not been peer-reviewed. This is not a “study”. It is a single-author, non-peer reviewed opinion piece that cherry-picks, misinterprets and conflates previous findings. “Most extreme weather phenomena have not become more extreme, more deadly, or more destructive.” There is an extensive and growing body of evidence showing that many kinds of extreme weather have increased in magnitude and/or frequency as the climate has warmed. Evidence is strongest regarding increases in extreme heatwaves and extreme precipitation events[14], but there is also extensive evidence regarding increasing intensity of other physical event types such as droughts, wildfires, and hurricanes (especially in specific regions). Indeed, there is now an entire sub-field of climate science, known as “extreme event attribution,” devoted to understanding how climate change is affecting the occurrence and intensity of extreme weather-related events[15]. Kerry Emanuel Professor of Atmospheric Science, MIT: Globally, the leading causes of mortality from weather phenomena during the period 1981-2020, in order, are drought, tropical cyclones, heat waves, floods, and convective storms. For most of these, when normalized by population, there are either no significant trends or downward trends[7]. In most, if not all, cases, this is attributable to improved emergency management. For example, there have been large decreases in tropical cyclone fatality thanks to far better warning, more and better evacuations, and in some places like Bangladesh, the massive construction of evacuation shelters[16]. Weather is taking fewer lives, but when one looks at damage the story is quite different. Since the early 1970s there has been a 380% increase in global weather-related damage normalized each year by world domestic product. Some of this is demographic; for example, there has been a 200% increase in coastal population, but much of the rest is owing to worse weather disasters, as measured by damage. From a strictly meteorological perspective, the latest consensus papers published in 2019 by Knutson et al. show a strong consensus that tropical cyclones will become more intense (but not necessarily more frequent) as the climate warms[4], and a paper published by Kossin in 2020 shows that the fraction of high intensity tropical cyclone observations has been increasing (see figure below)[17]. Figure 2—The proportion of major hurricane intensities to all hurricane intensities globally from 1979-2017. Data is binned into 3-year periods. The proportion of global major hurricanes increased by 25% over the 39-year time period analyzed. From Kossin et al. (2020)[17]. There is also a unanimous consensus that tropical cyclones will produce more rain, and in places with sufficient rain measurements, there is strong evidence for heavier rain events[4]. There is also strong evidence for an increase in the incidence of drought in some regions[1]. In a nutshell, deaths from extreme weather events are indeed decreasing but this is because of improving warnings, evacuations, and shelters, mostly in the developing world. There is strong evidence that weather events globally are becoming more destructive and more extreme[1]. “Empirical evidence directly contradicts claims that increased carbon dioxide has reduced human wellbeing. In fact, human wellbeing has never been higher” Jennifer Francis Senior Scientist, Woods Hole Research Center: The increase in atmospheric carbon dioxide does not directly affect human health, but it does directly cause increased global temperature and ocean acidification, and both of these are having major detrimental effects on human and ecosystem wellbeing. Carbon dioxide increase does not directly affect human well being, but the main process responsible for increasing CO2 is also responsible for air pollution that does directly affect human health[18,19]. In addition, many environmental consequences from anthropogenic greenhouse gas emissions and global warming have heavy costs in terms of human lives and life quality, for example heatwaves, famines due to drought, increase/expansion in infectious diseases[20,21]. There are “More hot days and fewer cold days” This is essentially the only scientifically accurate claim I can discern in the entire article. ”Cyclones/hurricanes [are not] more intense or frequent” While it is true that there remains no strong evidence for an increase in tropical cyclone (hurricane) frequency on a global basis, there is evidence that the most intense tropical cyclones are indeed becoming stronger (in terms of maximum wind speeds and minimum central pressure[17] and are producing more extreme rainfall[5]. In fact, these trends are consistent with predictions regarding tropical cyclone behavior due to global warming: there is a strong expectation that the maximum potential intensity of hurricanes will increase due to rising ocean temperatures, even as the overall frequency of such storms does not change greatly or perhaps even decreases[4]. “Tornadoes [are not] increas[ing] and becom[ing] more intense” There is relatively little evidence in either direction at this point in time regarding global or even regional trends in tornado frequency/intensity. This is largely due to sparse and temporally inhomogeneous historical records in the United States, and virtually non-existent records in other regions. There is some evidence of regional shifts in tornado frequency[22], and perhaps an increase in overall tornado “power” in the United States[23], but in general there is an absence of strong evidence regarding this claim. Future projections regarding climate change and tornado risk are of somewhat low confidence, but there is evidence that atmospheric environments favorable for severe convective storms (which are the types of storms capable of producing tornadoes) may increase in the future due to climate warming[24,25]. ”Droughts [are not] more frequent and intense” Observed spatial trends in global hydroclimate over the past century have been consistent with those expected from human influence in the climate system[26]. In many mid-latitude and subtropical regions, this has indeed included an increase in the frequency/intensity of drought[27,28]–but in other regions (such as the Northern Hemisphere high latitudes), this includes an increase in moisture availability and decrease in drought (as expected from climate model simulations). Therefore, it doesn’t really make sense to make blanket statements regarding overall global drought trends, since only some places are expected to get drier (and others wetter) in a warming climate.There has been no increase in the area burned by wildfire; the area peaked in the mid-19th century This is highly misleading, as it conflates different types of fire (many of which are not wildfires to begin with). Overall trends in area burned globally are strongly driven by decreases in intentional agricultural burning in tropical areas, which is not related to climate change. In regions where non-agricultural fires occur naturally (including the western United States[e.g., 29-31], eastern Australia[32], and the Siberian Arctic[33], for example) there is strong evidence that climate change has already increased the severity and extent of wildfire[34]. The statement that “Area burned by wildfire increasing — No (area peaked in mid-19th century)” is misleading in its implication that climate change is not making wildfires worse or more extreme and deadly. The overall global decrease is mostly driven by less fire in what used to be more extensive savannahs and grasslands and is largely due to the human driven removal of flammable vegetation. In quantitative terms, fire in those grassy ecosystems account for around 70% of the total global area burnt, so the reduction in fire activity here outweighs the increase in burned area that we are seeing in other parts of the world over the last two decades where fires have greater impacts such as Canada, parts of the USA or Siberia. In other words, where humans have not converted flammable landscapes to less or-non flammable landscapes by removing or changing the vegetation, warming temperatures are, overall, associated with an increase in fire activity. A very thorough recent global analysis of trends and fire knowledge overall is here[35]. And very importantly, associated with these regional increases, we have also seen a rise in fire impacts, for example in the number of fatalities. As reported in our wildfire trend analysis, in the period 1994-2014, an average of 71 deaths per year had been recorded in wildfire disasters recorded in the International Disaster Database[36]. Since 2015 this has risen to 122 deaths per year. The observed decline in global average area burned has been misused numerous times to support false claims about the role of climate change in wildfire trends. Climate change as well as human activities affect global fire activity (see here for a summary and update on Doerr and Santin, 2016[36]. “Cereal yields [are not] decreasing”; “they have tripled since 1961”; “Food supplies per capita [are not] decreasing” — they “increased 31 per cent since 1961” This is also misleading because crop yield increase since the 1960s is related to the massive increase in nitrogen fertilization and agricultural industrialization. However, studies have shown that extreme events made more likely by global warming are associated with losses in crop yields[37-39] and peaks in crop prices[40]. There are no “Land area and beaches shrinking, coral islands submerged”, instead there has been “marginal expansion” Ryan Sriver Associate Professor, University of Illinois: Observed expansion of beach areas is mainly due to human intervention and coastal management, not climate change. ”mortality from ‘Extreme Weather Events’ has declined by 99 per cent since the 1920s” No reference to this claim. On the contrary, scientific attribution studies such as Mitchell et al. 2016 show clear impacts of extreme events on excessive mortality[21]. ”fewer people are dying from heat; death rates from climate-sensitive diseases like malaria and diarrhoea have decreased (since 1900 malaria death rates have declined 96 per cent); hunger rates have declined; poverty has declined (GDP per capita has quadrupled since 1950 even as CO2 levels have sextupled); life expectancy has more than doubled since the start of industrialisation; health adjusted life expectancy has increased” All of these have multiple confounding factors (e.g. technological, health and economical development) so that these changes cannot be directly linked to CO2, but also do not invalidate negative effects of climate change. As such, this statement is simply misleading. [You can read this review to learn more about climate change impacts on health.] “Almost everywhere you look, climate change is having only small, and often benign, impacts. The impact of extreme weather events ― hurricanes, tornadoes, floods and droughts ― are, if anything, declining.” This contradicts the evidence presented in dozens of scientific contributions, and summarized in IPCC reports[1]. Jennifer Francis Senior Scientist, Woods Hole Research Center: This statement can be characterized as wishful thinking — contradicts all science-based evidence. It is misleading to state that flood magnitudes do not increase. Trend analyses of flood magnitudes in Europe have shown increases, decreases and no change depending on the location[41]. For example, increases have been observed in Ireland (during 1976–2009), Switzerland, Slovakia (for small catchments of 5–150 km2) and Norway (for rainfall-dominated catchments)[6,42-45]. Snowmelt floods, on the other hand, have been observed to decline in flood magnitude for Norway[45,46]. Rain-on-snow events (including floods caused by rain-on-snow) have been observed to increase at high elevations and decrease at low elevations, for Norway[47]. Future projections of flood magnitudes also show increases, decreases and no trends, depending on the location, catchment properties and flood-generating process. It is therefore misleading to state that flood magnitudes do not increase in the future. Madsen et al. (2014) write: “With respect to hydrological projections of changes in flood frequency at the catchment scale, both positive and negative changes in extreme discharge are projected. Increases in peak discharges are projected for sub-basins in the Scheldt and Meuse in Flanders (Boukhris and Willems, 2008, Willems et al., 2010), for catchments in Denmark (Sunyer et al., 2010, Madsen et al., 2013), for Bavaria and Baden-Württemberg (Hennegriff et al., 2006) and Saxony-Anhalt (Hattermann et al., 2011) in Germany, for western, mid-northern and all of coastal Norway (Lawrence and Hisdal, 2011), for the Hron catchment in Slovakia (Hlavcová et al., 2007), in coastal, southern areas in Sweden (Bergström et al., 2012), and in many catchments within the UK (Reynard et al., 2001, Reynard et al., 2010, Prudhomme et al., 2003, Kay et al., 2006, Kay and Jones, 2012).”[48] “Death rates from such events have declined by 99% since the 1920s.” So mortality rates from hurricanes and tornadoes have decreased since the 1920s until now. Is this because these storms are more “benign” now than they were in the past as the author suggests, or is it because we are now much better at forecasting and preparing for them now than we were 100 years ago (before the invention of computers)? “Even sea-level rise — predicted to be the most damaging impact of global warming — seems to be much less of a problem than thought, according to to the study’s findings.” This is literally the opposite of what a growing body of recent evidence has shown. Research actually shows that rates of global sea level rise have accelerated in recent years[49], and estimates regarding the upper end of plausible further SLR over the coming century have actually increased considerably as the non-linear contribution by continental ice sheets comes into clearer focus[50]. So, if anything, sea level rise is becoming more of a problem than previously thought. “A recent study showed that the Earth has actually gained more land in coastal areas in the last 30 years than it has lost through sea-level rise.” Jennifer Francis Senior Scientist, Woods Hole Research Center: Please provide this peer-reviewed study by a legitimate practicing environmental scientist to support this counterintuitive statement. This statement is false. The Earth has perhaps gained more “sandy beaches” along coastal areas according to the study cited. However, this is primarily due to coastal management, not sea-level rise. In fact, the authors of that study find large beach erosion in protected coastal areas (ie. regions without human intervention)[51]. “Nitrogen fertilisers and carbon dioxide fertilisation have together increased global food production by 111 per cent.” These are cherry-picked and highly misleading. The article cites increasing cereal yields as a reason why climate change is not a problem, but ignores the large evidence base showing that rising temperatures are damaging crop yields and slowing yield growth[11-13]. Moreover, benefits from CO2 fertilization saturate whereas damages from warming accelerate over time[9], meaning extrapolation from the historical record is not meaningful. To claim that nitrogen fertilizers are a benefit of fossil fuels is an extremely tortured logic and misleading in the extreme – synthetic fertilizers have very little to do with the question of how much to reduce energy generation from fossil fuels."
https://science.feedback.org/review/noaa-shows-clear-global-warming-trends-over-the-past-58-years-based-on-radiosonde-data/,Inaccurate,"Facebook, Facebook users, 2021-01-29","“The 58 year net gain of global temperature is zero. We are simply in a cyclical, normal ebb and flow of temperature.”",,"Inaccurate: Clear global warming trends of Earth’s ocean, land, lower and atmosphere have been observed over the past 58 years as well as over longer time periods. Radiosonde data collected from 1958 to 2019 also shows a pattern of warming in the lower atmosphere (troposphere).","Clear global warming trends of Earth’s ocean, land, lower and atmosphere have been observed over the past 58 years as well as over longer time periods. Radiosondes are used to collect upper air measurements from the troposphere and stratosphere. Most data comes from weather services that launch radiosondes at the same time all over the world to generate standardized observations that can be used to evaluate global trends in weather and climate. Radiosonde and satellite data from 1958 to 2019 demonstrate global warming.","NOAA graph doesn’t show a full record of radiosonde temperature data; ""the warming that has taken place in the last 37 years was preceded by a 21 year ""cooling"" period. The 58 year net gain of global temperature is zero. We are simply in a cyclical, normal ebb and flow of temperature.""",,"Review: The claim that there has been no increase in global temperature over the past 58 years was published by numerous users on Facebook in late January and early February 2021 (see example here), receiving thousands of interactions on the platform. This claim is incorrect, as data from NOAA has clearly demonstrated strong global warming trends over the past 58 years, as well as over longer timescales (see figure below)[1-3]. Figure 1—Global temperature anomaly data of Earth’s ocean and land surface relative to the 20th century average temperature from the Global Historical Climatology Network-Monthly data set and International Comprehensive Ocean-Atmosphere Data Set. These data sets show consistent global warming trends. From NOAA. The posts also make the incorrect claim that “we are simply in a cyclical, normal ebb and flow of temperature”. As stated in the IPCC 2014 report, “Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia.”[1] The Fourth National Climate Assessment also states, “Global annually averaged surface air temperature has increased by about 1.8°F (1.0°C) over the last 115 years (1901–2016). This period is now the warmest in the history of modern civilization. The last few years have also seen record-breaking, climate-related weather extremes, and the last three years have been the warmest years on record for the globe.”[2] The posts imply that NOAA is hiding radiosonde data because they released a graph from the past 37 years even though they had 58 years of data. However, the posts don’t show the graph or provide any references to support this claim. Although it is unclear from the posts, this claim may have originated from a 2016 blog post that claimed, “NOAA Radiosonde Data Shows No Warming For 58 Years”. This claim is false, as radiosonde data from 1958 to 2019 show a clear trend of global warming[4]. A radiosonde is a small instrument suspended from a large balloon that transmits data on pressure, temperature, and relative humidity. NOAA uses radiosondes to assess long-term temperature trends in some regions of the Earth’s atmosphere, including the troposphere and lower-stratosphere. Radiosonde data from 1958 to 2019 shows that the global warming rate of the troposphere is 0.18°C per decade[4]. These warming trends are also evident from satellite data (see figure below)[4,5]. Figure 2—Global annual temperature anomalies for the lower troposphere from radiosondes (top) and satellites (bottom) from 1958 to 2019. Adapted from Ades et al. (2020)[4]. Human-caused greenhouse gas emissions are expected to warm the lower troposphere while cooling the upper layers of the atmosphere[6]. This is because the lower troposphere acts as an insulating blanket that traps and re-emits infra-red radiations near the Earth’s surface. As more greenhouse gases are emitted into the atmosphere, more heat is trapped in the lower troposphere, resulting in a cooling effect in the upper layers of the atmosphere. Scientists’ Feedback: Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: This claim is false. Full time series of radiosonde (balloon-borne) temperature measurements (since 1958) are not new and are frequently depicted in routine climate reports. For example, in the State of the Climate in 2019 Report (on NOAA’s website), Figure 2.7 (in Global Climate, Figure reproduced above as Figure 2) shows the data since 1958 in a NOAA dataset (RATPAC vA2). The rate of warming over both the full period (1958 – 2019) and the satellite era (1979 – 2019) are noted in Table 2.3 (see table below). Both time periods show rapid warming of the Earth’s lower atmosphere (the troposphere). Similar data was shown in the report a decade ago (here)[7]. It is true that global atmospheric and surface warming is not perfectly linear and global temperature was relatively flat over 1958 – 1980. This feature is reproduced by climate models and is driven by human and volcanic emissions of aerosols (which tend to cool the planet). This is demonstrated, for example, in the Fourth National Climate Assessment (see interactive Figure 2.1). Global warming is not a myth and is evident in a wide variety of geophysical measurements of the Earth’s atmosphere, oceans, and cryosphere. “Radiosonde temperature data” are taken by weather balloons and NOAA’s “RATPAC” temperature record, which began in 1958, was published in 2005[8] and is currently on the NOAA website. Since “global warming” usually means near the surface where we live, here are NOAA weather balloon temperatures from the surface up to about 5.5 km (18,000’). Temperatures at the NOAA weather balloon stations have increased by about 1 °C (1.8 °F) since 1958 (see figure below).This Facebook post is misleading to say that NOAA “just released that they have 58 years” of this data, because it has been public for at least 15 years. That data shows about 1 °C (1.8 °F) warming since 1958, so the Facebook post is wrong to say “the 58 year gain of global temperature is zero”. It misleads readers by making up things that aren’t true. Unfortunately, there aren’t many weather-balloon stations and they usually launch from land, missing the ~70 % of Earth’s surface is ocean. Weather balloons are useful, but don’t give the most complete picture of global warming. That comes from weather stations, ships and buoys combined. Here is the 1880—2020 NOAA temperature record that shows the clear warming pattern since 1958 and before. Victor Venema Scientist, University of Bonn, Germany: The claim seems to be about NOAA’s radiosonde temperature dataset RATPAC, which includes data from 1958 to the present. That dataset currently spans 62 years, suggesting that the meme is 4-5 years old. NOAA’s RATPAC homepage gives four publications from 2003 and 2005 that showed data starting in 1958. In this case, the 37-year period would end in 2016, and the 37 years could correspond to a graph comparing radiosondes to the satellite retrievals, which start in 1979. Another reason the author of the claim may have seen data plotted starting in 1979 is that the more recent data is more reliable. The claim does not accurately describe the warming of the Earth. The land warming estimate of NOAA’s Global Historical Climate Network version 4 can be found below[9]. Clearly there was warming over the full period and the variations are not cyclical. The period 1958 to 1979, where the author of the claims that there is as much cooling as there is warming in the latter period is not warming. The reason for this is well understood: a fast increase in air pollution from a rapid expansion of fossil fuel use[10]. The above graph shows the temperature over land at the surface. The claim does not specify which temperature dataset they are referring to. It could describe the upper air temperature at the 850 mbar pressure level of RATCAP shown below[9]. Even at the 200 mbar level there is no warming and at the 50 mbar level the atmosphere is cooling. The warming at the surface and the cooling higher up are one of the predicted signatures of global warming due to an increase in greenhouse gases. Global warming refers to the warming at surface level. The station dataset is a much better way to estimate this. Not only are station observations made with better instruments of a higher quality than the one-use radiosonde data, but we also have many more stations, which gives a better estimate of the average warming, especially in the Southern Hemisphere. The longer period for which we have station data helps see that cycles the claim talks about are not an accurate description of global warming.REFERENCES: 1 – IPCC (2014) Climate Change 2014: Summary: for Policymakers. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. 2 – Wuebbles et al. (2017) Executive summary. In: Climate Science Special Report: Fourth National Climate Assessment, Volume I. 3 – Neukom et al. (2019) No evidence for globally coherent warm and cold periods over the preindustrial Common Era. Nature. 4 – Ades et al. (2020) Global Climate. Bulletin of the American Meteorological Society. 5 – Santer et al. (2017) Tropospheric Warming Over The Past Two Decades. Scientific Reports. 6 – Santer et al. (2013) Human and natural influences on the changing thermal structure of the atmosphere. PNAS. 7 – Blunden et al. (2011) State of the Climate in 2010. Bulletin of the American Meteorological Society. 8 – Free et al. (2005) Radiosonde Atmospheric Temperature Products for Assessing Climate (RATPAC): A new data set of large‐area anomaly time series. Journal of Geophysical Research. 9 – Menne et al. (2018) The Global Historical Climatology Network Monthly Temperature Dataset, Version 4. Journal of Climate. 10 – Haustein et al. (2019) A Limited Role for Unforced Internal Variability in Twentieth-Century Warming. Journal of Climate. UPDATES: 8 February 2021: This post was updated to include comments from Mark Richardson and Victor Venema."
https://science.feedback.org/review/prageru-post-by-william-happer-uses-flawed-reasoning-to-claim-that-climate-models-always-fail/,Incorrect,"PragerU, William Happer, 2021-01-24"," ""climate models that attempt to predict the future temperature of the planet...don’t work. They haven’t worked in the past. They don’t work now.""; ""the number of factors that influence climate—the sun, the earth’s orbital properties, oceans, clouds, and, yes, industrial man—is huge and enormously variable""; ""CO2 is a minor contributor to the warming of the earth""",,"Incorrect: Climate models can account for a variety of factors that influence Earth’s climate, including land, atmosphere, ice, and human activities. The effects of these factors can vary depending on the climatic pattern being evaluated. For instance, greenhouse gas emissions have a strong effect on global warming, whereas the Sun and the Earth’s orbital properties do not influence the global temperature over the timescales relevant to current warming trends. Climate models don’t need to perfectly capture every parameter to accurately model the average global temperature. State-of-the-art climate models have accurately reproduced past climatic patterns and forecasted future global warming trends. Human caused emissions of CO2 are a significant driver of global warming.","A variety of factors influence Earth’s climate, such as land, atmosphere, and ice, but not all aspects need to be perfectly modeled to produce useful forecasts of global temperature in climate models. State-of-the-art climate models have successfully forecasted global average surface temperatures over the past few decades.","""climate models that attempt to predict the future temperature of the planet...don’t work. They haven’t worked in the past. They don’t work now.""; ""the number of factors that influence climate—the sun, the earth’s orbital properties, oceans, clouds, and, yes, industrial man—is huge and enormously variable""; ""We can’t predict what effect the atmosphere is going to have on future temperatures because we can’t predict cloud formations""; ""Compared to water—H20, carbon dioxide—CO2—is a minor contributor to the warming of the earth""","1 – Hausfather et al. (2019) Evaluating the Performance of Past Climate Model Projections. Geophysical Research Letters. 2 – Shakun et al. (2012) Global warming preceded by increasing carbon dioxide concentrations during the last deglaciation. Nature. 3 – Feldman et al. (2015) Observational determination of surface radiative forcing by CO2 from 2000 to 2010. Nature. 4 – Santer et al. (2013) Human and natural influences on the changing thermal structure of the atmosphere. PNAS. 5 – IPCC (2014) Climate Change 2014: Summary: for Policymakers. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. 6 – Hayhoe et al. (2017) Climate models, scenarios, and projections. In: Climate Science Special Report: Fourth National Climate Assessment, Volume I. 7 – Gillet et al. (2021) Constraining human contributions to observed warming since the pre-industrial period. Nature Climate Change. 8 – Held and Soden (2000) Water Vapor Feedback and Global Warming. Annual Review of Energy and the Environment. 9 – Sherwood et al. (2021) An Assessment of Earth’s Climate Sensitivity Using Multiple Lines of Evidence. Review of Geophysics. 10 – Zelinka et al. (2020) Causes of Higher Climate Sensitivity in CMIP6 Models. Geophysical Research Letters. 11 – Chen et al. (2019) Advancements in Hurricane Prediction With NOAA’s Next‐Generation Forecast System. Geophysical Research Letters. 12 – Rappaport et al. (2009) Advances and Challenges at the National Hurricane Center. Weather and Forecasting. 13 – Cangialosi (2019) National Hurricane Center Forecast Verification Report. 14 – Rosenblum and Eisenman (2017) Sea Ice Trends in Climate Models Only Accurate in Runs with Biased Global Warming. Journal of Climate. READ MORE Carbon Brief published an in-depth article about how climate models work. UPDATES: 28 January 2021: This post was updated to clarify two sentences. 1 February 2021: This post was updated to include comments from Timothy Myers.","Review: The claim that climate models don’t work was published by William Happer in a post by PragerU, a group that has published misinformation in the past on a series of topics and boasts more than 4.5 billions views for the content it disseminates. The core claim of the post is that “the climate models that attempt to predict the future temperature of the planet … don’t work” and “over the last 30 years, one climate prediction after another – based on computer models – has been wrong”. However, this claim is contradicted by the fact that climate models have been found to skillfully forecast the evolution of global surface temperatures over the past few decades. In addition, the post doesn’t provide any evidence to support its claims. A 2019 study found that climate models published between 1970 and 2007 “were generally quite accurate in predicting global warming in the years after publication, particularly when accounting for differences between modeled and actual changes in atmospheric CO2 and other climate drivers”[1] (see figures 1, 2 and 3 below). These observations directly contradict the claim in the PragerU post. Read scientists’ comments below for further information. Figure 1 —A comparison of climate projections (black) from a model published in 1988 to observed differences in temperature relative to a 1958-1987 baseline (temperature anomaly). The black lines represent high (A), moderate (B), and low (C) emissions scenarios. From Hausfather et al. (2019)[1]. In support of this claim, Happer’s post provides several arguments. CO2 concentration changes are driving current climate warming, not H2O One argument is that “compared to water (H2O), carbon dioxide (CO2) is a minor contributor to the warming of the earth”. In reality, CO2 is a key driver of the current warming of global temperature due to its direct greenhouse effect (absorbing infra-red radiations) and its indirect effect called the water-vapour feedback. Both CO2 concentrations and water vapour feedback are already taken into account in state-of-the-art climate model simulations. Numerous scientific studies demonstrated that human-caused emissions of CO2 are the key driver of global warming over the past century[2,3,4]. As stated in a 2014 IPCC report, “Anthropogenic greenhouse gas emissions have…led to atmospheric concentrations of carbon dioxide, methane and nitrous oxide that are unprecedented in at least the last 800,000 years. Their effects…are extremely likely to have been the dominant cause of the observed warming since the mid-20th century.”[5] While natural factors, such as water vapor, do affect Earth’s climate, “Human emissions of carbon dioxide (CO2), methane (CH4), and other greenhouse gases now overwhelm the influence of natural drivers on the external forcing of Earth’s climate,” as stated in the 4th National Climate Assessment[6]. As described by Dr. Mark Zelinka below, “CO2 causes warming, and the warmer atmosphere contains more moisture, further enhancing Earth’s greenhouse effect”. The post is incorrect in stating that CO2 is a “minor contributor” to global warming and misleads readers by ignoring the fact that water vapour concentrations do not control variations in temperature but act as a feedback instead. The climate is a complex system, but not all aspects need to be perfectly modeled to produce useful forecasts of global temperature Another argument implies that Earth’s climate is too complex to be accurately modelled: “the number of factors that influence climate—the sun, the earth’s orbital properties, oceans, clouds, and, yes, industrial man—is huge and enormously variable”. While the earth’s orbital properties are important to explain past climate variations over timescales ranging from thousands to hundreds of thousands of years, they do not vary fast enough to have had any influence on the past hundred years of climate change. Dr Michael Wehner explains: “The number of factors influencing the climate is large, but they do not all affect the climate in equal ways. Climate models routinely include solar luminosity variations and orbital properties as external drivers. Human influences including atmospheric composition and land usage changes are similarly included as external drivers.” The post also uses flawed reasoning to conclude that climate models are wrong in general based on cherry-picking one example of a weather model that didn’t accurately capture the path of a single hurricane. In addition to being logically flawed, this argument confuses weather and climate. This is the same issue with the post’s claim that “Trying to figure out what two fluids will do in interaction with each other on a planetary scale over long periods of time is close to impossible”. However, forecasting the evolution of global temperatures does not require to perfectly model the behaviour of every water and air particle. Instead, it requires a proper understanding of forcings (change in solar radiations, greenhouse gases) and internal feedbacks (like the water vapour feedback and others). These feedback modulate the magnitude of the expected warming, but will not lead to a cooling for instance. This is akin to the “impossible expectations” argument, a technique used to deny climate change as explained in the book chapter The Five Types of Climate Change Denial Argument by Haydn Washington. Background on the author of the claim: William Happer is a retired physicist who did not lead scientific research on climate change. He co-founded the political advocacy organization CO2 coalition, and has previously made misleading statements about climate models and the impact of rising CO2. Scientists’ Feedback: The statements quoted below are from the post; comments are from the reviewers (and are lightly edited for clarity). “[Climate models] don’t work”; “the number of factors that influence climate—the sun, the earth’s orbital properties, oceans, clouds, and, yes, industrial man—is huge and enormously variable.” Mark Zelinka Research Scientist, Lawrence Livermore National Laboratory: All of these processes (and many others) are included in models, allowing them to simulate the climate. This assertion is simply wrong. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: This is not accurate; while models can never be a perfect representation of the Earth’s system, they do an excellent job of reproducing many aspects of the Earth’s climate, from rainfall and wind patterns to storm and hurricane formation and warming of the climate. In a 2019 paper we evaluated the performance of 17 historical climate model projections published between 1970 and 2001[1]. We found that 10 of those 17 projected a rate of future temperate change nearly identical to what actually happened in the real world in the years after they were published, while four of the models projected too much warming and three models too little warming[1]. This is particularly impressive for the 1970s-era models, which were published at a time when evidence of observed global warming was limited (and some even thought – based on limited observations – that the world was modestly cooling). Figure 2—Observed surface temperature change (HadCRUT5 – black line) compared to climate model projections from the years after the model was published (colored lines). Adapted from Hausfather et al. 2019[1]. Walter Hannah Climate Model Developer, Lawrence Livermore National Lab: While modelling the climate system involves dealing with a lot of uncertainty, solar activity and Earth’s orbit do not contribute much uncertainty. Making climate projections often revolves around a set of assumptions about anthropogenic emissions. These are often idealized, like a 1% increase in CO2 per year, but that does not make the results invalid. We can still learn a lot about the response of clouds and ocean circulation from studying these idealized experiments that can inform our response to the changing climate. Michael Wehner Senior Scientist, Lawrence Berkeley National Laboratory: The number of factors influencing the climate is large, but they do not all affect the climate in equal ways. Climate models routinely include solar luminosity variations and orbital properties as external drivers. Human influences including atmospheric composition and land usage changes are similarly included as external drivers. Ocean models are part of coupled climate models such as in the publicly available CMIP global climate models. Clouds are also part of the atmospheric components in these climate models. While clouds are the largest source of uncertainty, they are simulated well enough that this statement has no merit in my opinion. Timothy Myers Postdoctoral Researcher, Lawrence Livermore National Laboratory: The overall claim that “[climate models] don’t work” is illogical, vague, and seems to imply, hyperbolically, that the models have no use whatsoever. Climate models are imperfect representations of nature that represent just one tool scientists use to understand how and why Earth’s climate varies. Climate models are good at simulating some physical processes and deficient in their simulation of other processes. Simply because the climate is complex does not mean we cannot reasonably model or understand it. “Compared to water—H20, carbon dioxide—CO2—is a minor contributor to the warming of the earth.” Mark Zelinka Research Scientist, Lawrence Livermore National Laboratory: This is a well-worn trope that Dr. Happer unfortunately uses to mislead. Water vapor acts as a strong amplifier of warming initiated by CO2. I think of water vapor molecules as soldiers and CO2 as the commander. The commander decides to invade and the soldiers do most of the work. The soldiers do not randomly decide to invade. Similarly, water vapor cannot randomly decide to increase in the atmosphere. Rather, CO2 causes warming, and the warmer atmosphere contains more moisture, further enhancing Earth’s greenhouse effect – a textbook amplifying feedback. Michael Wehner Senior Scientist, Lawrence Berkeley National Laboratory: This statement is incorrect. This misses the point. Increases in CO2 affect the energy balance leading to more atmospheric moisture. Climate models incorporate the radiative properties of both compounds. This statement is incorrect. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: This is an incredibly misleading – and incorrect – statement. Water vapor is a powerful greenhouse gas, but it’s also one that is temperature limited. Water vapor has a very short lifetime in the atmosphere, so adding more water vapor by itself cannot effectively cause long-term climate warming. CO2, on the other hand, lasts for centuries to millennia in the atmosphere, and accumulates. Our best estimate is that around 100% of observed warming since the late 1800s is attributable to human emissions of CO2 and other greenhouse gases[7]. However, water vapor does have a role in that warming, but as a feedback rather than a forcing[8]. Higher temperatures caused by rising atmospheric CO2 increase the amount of water vapor in the atmosphere by increasing evaporation and by higher air temperatures allowing more water vapor to be present. This additional atmospheric water vapor enhances the warming from CO2 (and other greenhouse gases), but would not be in the atmosphere without their warming effects[8]. Walter Hannah Climate Model Developer, Lawrence Livermore National Lab: Water is more abundant and a more powerful greenhouse gas. However, the residence time of water vapor in the atmosphere is very short compared to CO2, and the spatial distribution of water is much less homogenous than atmospheric CO2. If humans were to emit a lot of water instead of CO2 it would be rained out rather quickly. With large and constant water vapor emissions we probably would see a change in the localized climate. None of this contradicts the fact that CO2 can also have an impact on the climate. Our CO2 emissions will elevate the atmospheric concentration for hundreds of years and contribute a small, but persistent, downward radiative flux over the whole planet. That small contribution is enough to be concerned about even if you can find other things that make it seem “too small”. Timothy Myers Postdoctoral Researcher, Lawrence Livermore National Laboratory: This is misleading and excessively vague. Water vapor is the primary and most abundant greenhouse gas in the atmosphere, and water in its liquid form in the oceans has an enormous capacity to retain and redistribute heat. Without water vapor, the planet would be much colder. But the increase of CO2 and other greenhouse gases due to human activity is the primary reason why the planet has warmed since the middle of the 20th century. “We can’t predict what effect the atmosphere is going to have on future temperatures because we can’t predict cloud formations.” Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: Clouds are one of the big areas of uncertainty in projecting future climate change, as they form on scales too small to directly simulate in climate models. Uncertainties in how clouds will change in a warming world is one of the main reasons why we are uncertain if doubling CO2 concentrations will warm the world by 2C or as much as 4.5C at equilibrium. However, suggesting that these cloud uncertainties mean that we can’t predict future changes is quite misleading. As discussed earlier, it’s clear that our climate models have performed quite skillfully in predicting the changes we’ve actually seen in the real world after they were published. A somewhat cloudy crystal ball is, after all, much better than no crystal ball at all. Walter Hannah Climate Model Developer, Lawrence Livermore National Lab: The biggest source of error in climate projections is how certain cloud types will react. This is a very active area of research right now, and probably will be for the next decade. However, I do not know of any credible climate scientist that feels that clouds could reverse the warming trend we expect from CO2. It’s possible that clouds will make the climate less sensitive than we thought, but that should not alleviate our concerns about the impact of global warming. For example, even a strong negative cloud feedback will not remedy the problem of ocean acidification from CO2, which is likely to be a very serious problem in the future. Mark Zelinka Research Scientist, Lawrence Livermore National Laboratory: Dr. Happer has correctly identified a key uncertainty in models’ predictions of future temperature – how clouds will respond to warming. This is a big reason why the scientific community tries to constrain models’ predictions using observations of how clouds respond to warming. We do not blindly accept model results as truth – we constantly evaluate them against observations, allowing us to hone our estimates of future warming. That said, we do not know *nothing* about future temperature — instead we have a range of plausible outcomes, all of which suggest a warmer future. Michael Wehner Senior Scientist, Lawrence Berkeley National Laboratory: Recent state of the art cloud system resolving models do very well in simulating intense storms and the cloud formations associated with them. Timothy Myers Postdoctoral Researcher, Lawrence Livermore National Laboratory: This is false. We know that Earth’s temperature will continue to rise as greenhouse gas emissions increase unabated. The most advanced, state-of-the-art predictions of the sensitivity of Earth’s climate to increasing carbon dioxide are based on multiple lines of evidence: observations, the paleoclimate record, theory, and models of varying complexity[9]. Based on this evidence, climate scientists estimate a likely range of the planetary warming resulting from a doubling of atmospheric carbon dioxide: 2.6-3.9 C (or 4.7-7 F). Climate models produce a wider range of the severity of planetary warming in response to increasing carbon dioxide[10]. This is primarily because their simulation of cloud processes is highly variable, with some models performing better or worse than others. However, a variety of independent evidence taken together reveals how clouds throughout the planet will likely behave as the climate warms, allowing scientists to predict future temperature changes with more precision than climate models simulate[9]. “A major aspect of climate involves the complicated interaction between two very turbulent fluids: the atmosphere, which holds large amounts of water (think rain and snow), and the oceans, which cover fully 70% of the earth’s surface…We can’t predict either side of the atmosphere/ocean equation.” Walter Hannah Climate Model Developer, Lawrence Livermore National Lab: We can (and we do) predict both of these systems reasonably well. Coupled models often produce strong regional errors, but this does not invalidate the basic conclusion about the concerning amount of warming we expect from elevated CO2. Michael Wehner Senior Scientist, Lawrence Berkeley National Laboratory: This statement is misleading. Climate science is a statistical one and we can simulate the statistical behavior of the relevant aspects of the climate quite well. In fact, simulations of future climate made in the 1990s have been shown to predict the present day warming very well. Furthermore, climate models are extensively independently evaluated by analysts not involved in model development. Clearly some aspects of climate model simulations can be improved, but the global energy budget is well simulated by nearly all models. Timothy Myers Postdoctoral Researcher, Lawrence Livermore National Laboratory: This is false. Many aspects of both the atmosphere and ocean are predictable, though the degree of predictability varies depending on the process in question. A recent study finds that “climate models published over the past five decades were generally quite accurate in predicting global warming in the years after publication”[1]. If models can’t predict the path of a hurricane, they can’t predict climate over the last 30 years, “one climate prediction after another – based on computer models – has been wrong.” Mark Zelinka Research Scientist, Lawrence Livermore National Laboratory: This is another well-worn trope. Dr. Happer has unfortunately confused weather and climate in this statement. The accuracy of weather forecasts – and in particular extreme events like hurricanes – can be degraded by poor data about the current state of the atmosphere that gets fed into the models. These issues are very different from those that affect climate model predictions – namely, how clouds and humans will respond in the future. Secondly, the nature of weather forecasts (“what is the probability of rain in my city tomorrow afternoon?”) are very different from climate projections (“how much warmer on average will the 2050s be in California?”). It is also worth mentioning that hurricane track forecasting is becoming extremely skillful, in contrast to Dr. Happer’s assertion. Cherry picking a bad hurricane track forecast to throw shade on climate model projections is like claiming Tom Brady isn’t going to the Hall of Fame because he burned his breakfast yesterday. Michael Wehner Senior Scientist, Lawrence Berkeley National Laboratory: I think that the National Hurricane Center would beg to differ. Hurricane track forecasting has improved dramatically over the past few decades and has led to substantially reduced fatalities[11,12]. The statement is a (false) assertion, without any evidence. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: Modern weather models – which share many parts of their code with our long-term climate models – are actually quite good at predicting hurricane tracks[13]. Moreover, the fact that our prior model projections have proven quite accurate at estimating how much warming actually occurred gives us confidence that our models – while imperfect – are accurate enough to get a good sense of how much warming to expect in the future if we keep emitting CO2 and other greenhouse gases. Figure 3—Historical temperatures (colored lines) and the last generation of climate models (black line shows the model average, with the grey shaded area representing the range across all the models). From: https://www.carbonbrief.org/state-of-the-climate-2020-ties-as-warmest-year-on-record Walter Hannah Climate Model Developer, Lawrence Livermore National Lab: Let’s think about this idea that “computer models are always wrong”. Computer models do amazingly well at a lot of things, but it is also very easy to find little things that they do not do well at. It is not fair to judge all weather and climate models based on only the things they do wrong. One model might not rain enough in one area of the globe, but even if it gets it mostly correct everywhere else people will criticize the model for being “wrong”, which is completely unfair. Hurricane forecasts are another good example where they can be right most of the time, only to then be harshly judged when they get the hurricane track wrong. We care about these small errors because they can potentially mean an unexpected loss of life or property, but to use blanket statements about all computer models being wrong is simply dishonest or naïve. Timothy Myers Postdoctoral Researcher, Lawrence Livermore National Laboratory: This is an illogical statement and misleading. The author is conflating weather forecasting of a hurricane with long-term climate prediction, and more fundamentally, he is conflating weather with climate. As the American Meteorological Society states, climate is defined as “The slowly varying aspects of the atmosphere–hydrosphere–land surface system. As distinguished from climate, weather consists of the short-term (minutes to days) variations in the atmosphere.” Simply because some weather forecasts are inaccurate does not imply that changes in climate are unpredictable. Climate model projections are not intended to forecast changes in the atmosphere as precisely as the particular path of a single hurricane. Some of the main elements of the climate that models are used to predict are changes in large-scale patterns of temperature, humidity, precipitation, and wind. It’s false to say that “Over the last 30 years, one climate prediction after another — based on computer models — has been wrong”. Models accurately predict some climate changes and imprecisely predict others, with some overpredictions and some underpredictions. For example, a recent study finds that “climate models published over the past five decades were generally quite accurate in predicting global warming in the years after publication”[1]. To take another example, climate models tend to underestimate the rapid Arctic sea ice decline observed in recent decades[14]."
https://science.feedback.org/review/video-interview-of-ian-plimer-at-sky-news-falsely-claims-that-a-new-study-announces-an-incoming-ice-age-partly-based-on-an-incorrect-daily-mail-headline/,-2,"Sky News Australia, Daily Mail, by Ian Plimer, on 2021-01-13.",,"""“Earth's climate is 'cyclical' as new study claims an ice age is coming”""",,,,"1 – Starr et al. (2021) Antarctic icebergs reorganize ocean circulation during Pleistocene glacials. Nature. 2 – Keeling (1979). The Suess effect: 13Carbon-14Carbon interrelations. Environment International. 3 – Eide et al. (2017). A global estimate of the full oceanic 13C Suess effect since the preindustrial. Global Biogeochemical Cycles. 4 – Meehl et al. (2020). Context for interpreting equilibrium climate sensitivity and transient climate response from the CMIP6 Earth system models. Science Advances. 5 – Shakun et al. (2012). Global warming preceded by increasing carbon dioxide concentrations during the last deglaciation. Nature. 6 – (2011) Climate past and future. Nature Geosciences. 7 – Feldman et al. (2015). Observational determination of surface radiative forcing by CO2 from 2000 to 2010. Nature. 8 – IPCC (2014) Climate Change 2014: Summary: for Policymakers. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. 9 – Caeser et al. Observed fingerprint of a weakening Atlantic Ocean overturning circulation. Nature. 10 – Peterson et al. (2008) The myth of the 1970s global cooling scientific consensus. Bulletin of the American Meteorological Society. 11 – Keigwin et al. (2018) Deglacial floods in the Beaufort Sea preceded Younger Dryas cooling. Nature Geoscience. 12 – Broecker et al. (2010) Putting the Younger Dryas cold event into context. Quaternary Science Reviews. 13 – Huybers et al. (2006) Links between annual, Milankovitch and continuum temperature variability. Nature. 14 – Markonis et al. (2013) Climatic Variability Over Time Scales Spanning Nine Orders of Magnitude: Connecting Milankovitch Cycles with Hurst–Kolmogorov Dynamics. Surveys in Geophysics. 15 – Sigman et al. (2000) Glacial/interglacial variations in atmospheric carbon dioxide. Nature. 16 – Archer et al. (2005). A movable trigger: Fossil fuel CO2 and the onset of the next glaciation. Geochemistry, Geophysics, Geosystems. 17 – Tzedakis et al. (2012). Determining the natural length of the current interglacial. Nature Geoscience. 18 – Bader et al. (2020). Global temperature modes shed light on the Holocene temperature conundrum. Nature Communications. 19 – Kaufman et al. (2020). Holocene global mean surface temperature, a multi-method reconstruction approach. Scientific Data. 20 – Ganopolski et al. (2016). Critical insolation–CO 2 relation for diagnosing past and future glacial inception. Nature. 21 – Lisiecki et al. (2005). A Pliocene‐Pleistocene stack of 57 globally distributed benthic δ18O records. Paleoceanography. 22 – Petit et al. (1999). Climate and atmospheric history of the past 420,000 years from the Vostok ice core, Antarctica. Nature. 23 – Hönisch et al. (2009). Atmospheric carbon dioxide concentration across the mid-Pleistocene transition. Science. 24 – Cui et al. (2020). A 23 m.y. record of low atmospheric CO2. Geology. 25 – Rubino et al. (2013) A revised 1000 year atmospheric δ13C‐CO2 record from Law Dome and South Pole, Antarctica. Journal of Geophysical Research: Atmospheres.","Reviewers’ Overall Feedback: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Twila Moon Research Scientist, University of Colorado, Boulder: This video is chock full of false and misleading information, and presented in a way to make the correct scientific information seem like a farce. For example, the direct link between human emissions of carbon dioxide and global warming is very well established[8]. The physics and chemistry of this link has been understood for well over 100 years, and science continues to affirm it. In another example, projections of the Earth’s future temperature – created through the efforts of thousands of scientists across the globe – show that the planet will continue to warm under all scenarios of continued emissions of heat-trapping gases. There will NOT be a sudden natural cooling over the coming centuries. Humans are warming the planet, and human actions will continue to be the primary control on future temperature trends for the Earth. Peter Neff Assistant Research Professor, University of Minnesota: This fawning, biased interview with Sky’s favorite denier missed the point of the new paper about Antarctic iceberg and freshwater forcing on ocean circulation[1]. If they’d only read the Daily Mail article about this work, they’d see this statement: “Over the past three million years the Earth has regularly plunged into ice age conditions, but at present is currently situated within an interglacial period where temperatures are warmer. However, it may not happen again in the same way, due to the impact of human-created CO2 emissions warming the world.” For Plimer to think that human activities don’t affect planetary energy balance means he possesses arrogance that far eclipses his understanding of Earth’s climate system. Alexis Berg Research Associate, Harvard University: The starting point of the segment is an article in the Daily Mail, which mistakenly claims scientists are now warning of an incoming ice age, in a new study[1]. The study in question does no such thing, of course (which is actually clear if you read, not even the study, but the Daily Mail article itself), but the host and his guest, Ian Plimer, are not ones to care for such details and are all too happy to seize on this misleading, sensationalist headline to then deliver the usual mix of cherry-picked, out-of-context, and flatly wrong elements that have been addressed many times before, such as “climate has varied before”, “not unprecedented”, and “it’s the sun”. Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: In this video Cory Bernardi and well known climate science denier Ian Plimer deliberately misrepresent the findings of a recent article published by Starr et al. in Nature[1]. They imply that the mechanism proposed in the paper, ie., a reorganisation of the Atlantic Overturning cell due to changes in Antarctic iceberg-derived freshwater fluxes during glacial periods can somehow be applied to the present day and as a result, that a glacial period is imminent. This is patently absurd – the described mechanism is one feedback in a series that are required for a glacial inception and cannot simply be applied in isolation to the present day climate in which we have dramatically increased concentrations of atmospheric CO2, a potent greenhouse gas. Ian Plimer of course ignores this – claiming that climate is cyclical and that no one has ever proven anthropogenic CO2 to have driven global warming. Both claims have been extensively debunked here at Climate Feedback on previous occasions (see reviews here, here, and here), but to offer a brief refutation of the first point: The Earth’s climate is indeed cyclical over time-periods of multiple millennia and are driven primarily by the Earth’s orbital cycles. It is true that we are currently in a warm interglacial period and that up until the late 19th and early 20th Centuries, the world was gradually cooling again (see this figure by Ed Hawkins). However, the magnitude of greenhouse gases we have emitted into the atmosphere and the rate at which we have done so has been sufficient to overpower this natural cycle and warm the Earth considerably. Even with a slow down (which we have observed and even expect in a warming world)[9], or even shutdown of the Atlantic overturning circulation, this warming will continue as long as concentrations of greenhouse gases increase. Dan Jones Physical Oceanographer, British Antarctic Survey: This video features a large number of incorrect statements. Many of these statements are myths that have been debunked again and again. In the video, Plimer and the anchor suggest that climate scientists in the 1970s predicted an ice age. This is not an accurate summary of scientific thinking in the 1970s. Peterson et al. (2008) showed that global warming was a prominent hypothesis in that decade[10]. They claim that “We are getting towards the end of a warm period. The peak of the warmth was about 5,000 years ago and we are heading to the next inevitable ice age.” There is no evidence for this claim. Plimer is essentially stating, without evidence, that the climate system will continue operating just as it has for hundreds of thousands of years. This statement ignores the fact that the climate system changes that we have already observed have the fingerprints of human activity all over it (e.g., the stratosphere is cooling, which is a characteristic pattern of global warming). You cannot explain recent warming since the 1850s without including human-driven carbon dioxide emissions. They claim, “No one has ever shown that human emissions of carbon dioxide drive global warming.” This is a misleading statement that ignores the entire history of climate science. We have known since the time of the US Civil War (the UK Victorian Era) that carbon dioxide acts as a greenhouse gas. If more carbon dioxide is added to the atmosphere, then more energy will arrive at Earth’s surface. Adding energy to the climate system will change it; that extra energy does not simply vanish. Notably, we cannot explain warming since the 1970s using natural factors alone; we have to consider anthropogenic greenhouse gas emissions to explain this decadal scale warming. Ian Plimer has strong connections to the Australian mining industry, which has a personal stake in preserving our current fossil-fuel heavy energy system. This was not disclosed during the interview, as Plimer was simply presented as a geologist. In the interview, Plimer suggests that the Australian Bureau of Meteorology is only using relatively short records of the past few decades to understand climate change. This statement ignores how climate science operates. The scientists working at the bureau will also be familiar with the literature on long-term climate change; it is disingenuous to suggest that they somehow don’t have access to or an understanding of the data and literature on long-term climate cycles. Plimer goes on an irrelevant rant about the education system, suggesting that anyone who disagrees with him is somehow poorly educated. This is an example of the “No true Scotsman” logical fallacy and is incorrect reasoning. David Battisti Professor of Atmospheric Sciences, University of Washington: It is old news (50+ years) that glacial cycles are due to changes in insolation (not CO2) that are due to variations in the orbit of the Earth around the Sun, and that these glacial cycles have time scales of 40,000 -100,000 years. Many of the statements in this video make it clear that the commentator (Plimer) does not understand the scientific article, which relates to a potential feedback that may operate in glacial cycles. But the main thrust of the comments made in the interview concern whether changes in CO2 impact climate, whether humans are responsible for the increases in CO2, and the impacts of the increased CO2 on climate. The reviewer asks for 5 papers that show these links. I will simply note that the all 5 IPCC Assessment reports document the overwhelming evidence (thousands of peer reviewed papers) that: (i) CO2 is increasing due to burning of fossil fuels, that (ii) the warming of the planet seen since 1850 is much greater than can be explained by solar forcing, but it is entirely consistent with the warming expected due to the observed increase in CO2 and changes in atmospheric aerosols (also due to human activity). Michael Lockwood Professor of Space Environment Physics, University of Reading: The idea of an ice age being triggered by global warming appears to be an extrapolation of what happened at the end of the last ice age in an interval called the Younger Dryas. As the world emerged from the last ice age it was pitched back into this further cold interval (named after a flower that thrived in the cold throughout Europe at the time). There have been a number of theories of its origin, of which some are now generally discounted, such as a comet impact. It is known that as the world warmed, a huge meltwater lake (Lake Agassiz) formed on the north American continent, the remnants of which today are the Great Lakes. A disruption of the Atlantic MOC (i.e. the Gulf stream) by the escaping cold, salt-free meltwater may have caused a temporary reverse in the global warming and a temporary return to ice age conditions[11]. Whatever the mechanism, it is thought such an event is likely to have been an inevitable consequence of the end of the glaciation[13]. As an analogy and predictor for what might happen because of present global warming, it is of no relevance whatsoever: the global warming involved in causing the Younger Dryas was that at the end of an ice age – the ice sheets that melted were vast and reached down to temperate latitudes (in the UK it reached Oxford!). The video invokes solar changes as a cause of ice ages. This is wrong. They are intimately connected by changes in Earth’s orbit around the Sun – the so called “Milankovich cycles”[13,14]. These are indeed cycles and it is certainly true that Earth will return to another ice age. It is also true that another ice age is “due” in the sense that the present interglacial (warm period), the holocene, has been unusually long. The quip about it happening on a Tuesday hides the central fallacy here. The Milankovich cycles are extremely long and what is “due” on their timescales is far, far into the future even on the timescale of anthropogenic global climate change which has been centuries (but is now rapidly turning to decades). The video says carbon dioxide rose at the start of ice ages. This is not true. We know well how the abundances of all atmospheric gases, including CO2, changed during ice ages from analysis of air bubbles in ice sheets and dating when that ice formed[15]. Carbon dioxide fell during the ice ages – not because it had any causative role in forming the ice age (as explained, above they are caused by changes in Earth’s orbital characteristics), rather, because colder water can store more carbon dioxide and because much carbon dioxide became locked into the ice and no longer took part in the carbon cycle exchanges between the atmosphere and the oceans and biosphere. We know this was a response and not a cause because the CO2 changes lag, not precede, the temperature changes. Lastly, asking for 5 papers that show that anthropogenic carbon dioxide is causing global warming reveals a complete failure of understanding of the science – indeed of science in general. It is like asking for 5 papers that prove that a pain in your stomach, head or chest is due to cells on your body in which the cell division (which is part of the normal replacement and replication procedure in growth and repair) has gone into overdrive: in other words, what we refer to in a shorthand as a cancer. Our knowledge of cancer and its causes does not rest on 5 papers, nor can it be summed up in 5 papers. It rests on thousands and thousands of papers which cancer experts knit together into a coherent understanding. It is exactly the same with climate change science. Annotations: The statements quoted below are from the article; comments are from the reviewers (and are lightly edited for clarity). “Cardiff University has released a study on the ice ages, It claims that icebergs melting in the Antarctic may actually trigger a reaction that plunges Earth into an ice age.” Ian Hall Professor, Cardiff University: This statement ignores the key finding from our study – we find that the climate systems response to Antarctic icebergs is highly sensitive to where they melt. We specifically describe the sequence of events which occurred during past interglacial to glacial conditions over the last 1.5 million years. Alexis Berg Research Associate, Harvard University: The authors of the study did not say that – as the Daily Mail notes itself. Paleoclimate scientists understand that the cyclical ice ages of the last million years or so are linked to small, cyclical changes in the Earth’s orbit, but the exact mechanistic details are not fully understood: the new Nature paper that the Daily Mail reports on, suggests a role for changes in the spatial patterns of iceberg melt in the inception of past ice ages. It doesn’t say current melt is going to trigger a new ice age: as the Daily Mail itself writes, “The impact of human-created CO2 emissions could make the Southern Ocean too warm for Antarctic icebergs to reach, bringing an end to this 1.6 million year cycle of ice ages starting with melting icebergs, study authors warned.” So, kind of the opposite actually. So the article headline is plain wrong, and so is the premise of the Sky News segment. “But I thought alarmists were telling us that our approach to climate was leading us into believing that we’re the direct cause of global warming and we’re all going to boil and now we’re saying the ice age is coming again.” Ian Hall Professor, Cardiff University: Our paper is unambiguous and not relevant for modern/future climate change in this way, and reporting it as so is fundamentally misinterpreting our findings. In fact, in the press release for the study, we emphasise that our findings are specifically related to natural “Milankovitch” cycles in orbital forcing, however with current human greenhouse-gas emissions and increasing global temperatures, the Southern Ocean is likely too warm for icebergs to be transported as described in the paper and melt in the regions necessary for the chain of events we highlight to be triggered. Our study does not say or imply that an ice age is coming. It does emphasise the importance of understanding iceberg trajectories and melt patterns in developing the most robust predictions of their future impact on ocean circulation and climate. “What’s going on is cycles – we’re getting towards the end of a warm period, the peak of the warmth was about 5000 years ago, and we are heading for the next inevitable ice age.” Ian Hall Professor, Cardiff University: “What’s going on is cycles” is at least a reference to our paper. However, the paper does not deal with modern (post-industrial) climate timescales. The statement by Ian Plimer is not supported by the majority of scientific evidence regarding the duration of the ‘present interglacial’. Plimer here is lacking an understanding of the concept of thresholds. It is well established that the onset of a glacial period has only ever, and can only ever, occur when atmospheric CO2 is below a certain threshold. When atmospheric CO2 concentration is too high, the orbital forcing which favours an ice age is simply not enough to cause an ice age. For example, a study by Archer and Ganapolski (2005) found that no glacial inception will occur with atmospheric CO2 concentrations above 400 ppm[16]. Tzedakis et al. (2012) go on to show that under the current orbital configuration, a CO2 concentration of below pre-industrial levels would be required for an ice age to begin[17]. Hypothetically, if atmospheric CO2 was lower than around 240 ppm, we might have seen the inception of an ice age develop at some point over the coming several millennia. However, as we approach atmospheric CO2 concentrations of double this, caused by human greenhouse-gas emissions, the scientific consensus is clear: we are not currently heading for an ice age. Regarding the “5000 year cooling trend” alluded to by Plimer, it is important to recognise that this is still an active area of research. Whether the Holocene was characterised by a long-term cooling or warming trend is a more complex question than this comment suggests. It is in fact likely that different temperature trends prevailed over different regions[18]. Whilst Holocene climate variability is an interesting exercise in our understanding of the climate system, it is important to remember that regardless of whether there was a long-term cooling or warming trend over the Holocene, the warming we have experienced since the industrial era is unprecedented in its rate – this is not part of some long-term trend, it is very clearly an anthropogenic perturbation of the climate system. Alexis Berg Research Associate, Harvard University: It’s true that we are in an interglacial period, the Holocene, which, prior to the abrupt warming of the past century, had been warmest around 6000 years ago, as far as paleo-climate scientists can reconstruct. However, owing to recent man-made warming, there’s every indication that current temperatures are now on par with the warmest temperatures of even that period[19], and they will continue to increase because of greenhouse gas emissions, to a level (for instance, +3 degrees compared to pre-industrial temperatures) probably not seen in the last couple million years. So we are not headed into an ice age any time soon. In fact, a study in Nature showed that, even without man-made CO2 emissions and warming, the next orbitally-driven ice age would probably not have happened before another 50,000 years (which is a bit unusually long)[20]; and given current man-made warming, now it won’t happen for another 100,000 years[19,20]. “We’ve had 6 major ice ages, during which we’ve had glaciations and warmer periods – all of that happened before humans were on planet earth.” Ian Hall Professor, Cardiff University: It is not clear where Plimer got the number 6 from here. Using a conservative definition of an ice age, there have been at least 10 in the last 1 million years, with over 50 since the development of a substantial northern hemisphere ice sheet[21]. Peter Neff Assistant Research Professor, University of Minnesota: Causes of past climate fluctuations are relatively well understood, paced by slight changes in Earth’s orbit around the sun (Milankovitch cycles). That human emissions of greenhouse gases are currently trapping heat and warming the planet is accepted fact. Our activities now exert more control on Earth’s climate than orbital variations, and will override any coming ice age based on orbitally-induced decreases in the amount of incoming solar radiation. “Every single major ice age started when we had more CO2 in the atmosphere than now.” Ian Hall Professor, Cardiff University: Again, it is not clear where this claim comes from, it is simply not supported by any existing records of atmospheric CO2 over the Pleistocene[22,23]. The highest CO2 concentration recorded in ice core records (0 – 800 thousand years ago) is around 300 ppm[22]; the highest Pleistocene CO2 reconstructed using geochemical proxies (boron isotopes) is similar, around 300ppm[23]. Indeed, over the past 23 million years, CO2 has never reached atmospheric concentrations as high as today, maxing out at around 350 ppm during the mid-Miocene[24]. “No-one has ever shown that human emissions of carbon dioxide drive global warming. If you think it has been shown, please give me the 5 scientific papers that show this.” Ian Hall Professor, Cardiff University: Among the vast scientific literature on this topic, the following 5 papers are a good starting point: How do we know that the increased atmospheric CO2 concentrations are from humans burning fossil fuels? The Suess effect[2,3]. How do we know that this CO2 drives global warming? Our understanding of the physics of radiative forcing date back at least to the work of Svente Arrhenius (1859 – 1927). This is not a contentious topic in the modelling of Earth’s climate system. From the simple to the sophisticated, our models of the climate system are unequivocal[4], as are the geological data[5,6]. Alexis Berg Research Associate, Harvard University: This rhetorical and, frankly, absurd point by Ian Plimer (and others) has been addressed before in other reviews. Yes, there is no one silver bullet argument, but multiple lines of evidence. In a way it’s a akin to a murder trial: sure, there is no one videotape absolutely “proving” that CO2 killed the victim, but we know CO2 was there, had the means and the motive (it’s a greenhouse gas), there’s even partial eye witness account (showing the increase in greenhouse effect in observations)[7], there is DNA evidence (~climate modeling shows CO2 explains the warming well) and all the other possible suspects (sun, volcanoes, etc) have solid alibis. So the case has been solved for a while now[7]. Peter Neff Assistant Research Professor, University of Minnesota: This is an easily verified falsehood. Plimer should be aware of work by Australian colleagues at the Commonwealth Science and Industrial and Research Organization (CSIRO) that shows how carbon dioxide emissions have rapidly increased in the last 150 years, using Antarctic ice and bubbles of old air trapped inside (locked in as snowflakes trap air between their fingers and are buried). The Law Dome research site in Antarctica is a keystone in our understanding of the atmospheric carbon budget going back the last 2000 years. I was a leader of the most recent scientific expedition to this important location, and can verify that the work of Plimer’s fellow Australian’s at this site is world class (see here). Not only is a ~40% increase in carbon dioxide observed in the last 150 years, but the stable isotope of carbon, 13-C has declined over that period. That definitively indicates that the carbon dioxide being emitted comes from a source depleted in 13-C, which provides clear evidence for attribution of industrial period carbon dioxide variations to human activity (fossil fuel hydrocarbons are depleted in 13-C). See figure 6 of Rubino et al., 2013 below[25]. “People have very little outdoor experience…We have a city-based population that doesn’t read the scientific literature, that has had no life experience.” Peter Neff Assistant Research Professor, University of Minnesota: Plimer goes on to make absurd arguments based on common cultural tropes and lines of division, suggesting that those living in cities and having “very little outdoor experience.” This has nothing to do with one’s understanding and experience of climate and has no relevance to the science of climate change and the unprecedented warmth that Australia’s Bureau of Meteorology reports year after year. Given our understanding of the factors at play, it is clear that human emissions of greenhouse gases is trapping excess heat in the atmosphere, causing warming that is particularly impacting Australia by way of extreme drought and severe fires. Australia’s temperature has been rapidly rising since this new anthropogenic warming emerged in the last ~century. The climate of the deep past is immaterial here, as this time is not analogous to the working of Earth’s climate system today, as any geologist would know if they were properly educated at a modern, degree-granting institution of higher education. From the Australian Government Bureau of Meteorology.“Most of [the cycles in climate] are driven by… the sun.” Peter Neff Assistant Research Professor, University of Minnesota: This is again, easily disproven. Solar variability does not exert warming that matches observed temperature increases. See US National Climate Assessment 4, Figure 2.1 below."
https://science.feedback.org/review/rates-of-global-sea-level-rise-have-accelerated-since-1900-contrary-to-bloggers-claims/,Inaccurate,"NoTricksZone, Watts Up With That?, Kenneth Richard, Pierre L. Gosselin, 2021-01-11",“there has not been a long-term distinctive change in sea level rise rates in the last 120 years”,,"Factually inaccurate: Global sea level has risen at an increased pace since industrialization, with the fastest rates of sea level rise occurring in the late 20th century. Cherry-picking: The article only reports average rates of global sea level rise from two time periods and two studies, while ignoring all the other available data demonstrating that rates of sea level rise have accelerated since the 1990s.","The rate of global sea level rise has changed over the past 120 years and accelerated since the early 1990s, based on tide gauge and satellite data. Current sea level rise primarily results from glacial ice melting and the expansion of seawater as it warms due to human-caused global warming.","“A new analysis of global sea level rise rates concludes the rising trend was 1.56 mm/yr−¹ from 1900-2018. This is the same rate as for 1958-2014 (1.5 mm/yr−¹), indicating there has not been a long-term distinctive change in sea level rise rates in the last 120 years. Neither of these trends would appear to correlate well with the linearly accelerated rise in CO2 emissions since the 1940s.”","1 – Frederikse et al. (2018) A Consistent Sea-Level Reconstruction and Its Budget on Basin and Global Scales over 1958–2014. Journal of Climate. 2 – Frederikse et al. (2020) The causes of sea-level rise since 1900. Nature. 3 – Dangendorf et al. (2019) Persistent acceleration in global sea-level rise since the 1960s. Nature Climate Change. 4 – Horton et al. (2018) Mapping Sea-Level Change in Time, Space, and Probability. Annual Review of Environment and Resources. 5 – Slangen et al. (2016) Anthropogenic forcing dominates global mean sea-level rise since 1970. Nature Climate Change 6 – Church and White (2011). Sea-Level Rise from the Late 19th to the Early 21st Century. Surveys in Geophysics.","Review: The claim that rates of sea level rise haven’t significantly changed in the past 120 years appeared in blog posts published by NoTricksZone and ‘Watts Up With That?’ in January 2021. Contrary to the claim, scientific studies show that rates of global sea level rise have changed over time and accelerated, notably since the 1990s, primarily due to glacial ice melting and the expansion of seawater as it warms[1-4]. To evaluate how the rate of sea level rise has changed over time, scientists evaluate long-term trends in mean sea level, primarily based on data from tide gauges and satellites. They can then use these observations to calculate whether this rate has increased, decreased, or remained the same over time. These studies consistently show a distinct pattern of accelerated rates of global mean sea level (GMSL) rise since the 1990s (see figure 1)[2,3]. Figure 1—Global mean sea level (GMSL) trend in mm per year from 1900 to 2015, based on data from tide gauges and satellites. From Dangendorf et al. (2019)[3]. Instead of evaluating all available scientific studies exploring rates of global sea level rise, the bloggers only present data from two time periods and two papers, ignoring everything else and drawing a misleading conclusion. Furthermore, the bloggers do not calculate the rate of acceleration in GMSL. Doing so would indicate that GMSL has accelerated at a rate of about 0.012 mm yr-2 from 1900 to 2018, as Frederikse, the author of the study on which the bloggers rely, describes below. Therefore, the bloggers’ claims are inaccurate and based on cherry-picked data. While the overall rate of GMSL has accelerated since 1900, the rate of change also varies over time. Specifically, there were higher rates of sea level rise during the 1940s and since the 1990s and lower rates of sea level rise in the 1920s and 1970s(see figure 1)[2,3]. One study demonstrates that the rate of GMSL has accelerated over the past two decades, estimating that from 1993 to 2018 GMSL rose 3.35 mm per year, more than double the average rate from 1900-2018[2]. These estimates of accelerated rates of sea level rise are supported by additional scientific studies. For instance, Dangendorf et al. (2019) describes, “the pace of GMSL has been accelerating since 1993, which is consistent with independent estimates of increasing mass contributions from Greenland and Antarctica over the last two decades.”[3] An analysis from 14 studies that estimates rates of GMSL using satellite and tide gauge data also show clear patterns of accelerated rates since 1993 (see figure 2)[4]. Figure 2 – Rates of sea level rise over the 20th century (green) and since 1992 (blue). The time windows for each paper cited are as follows: (a) 1993–2014; (b) 1993–2014; (c) 1993–2010; (d) 1993–2009; (e) 1901–1990 (green), 1993–2012 (blue); ( f ) 1901–1990; (g) 1901–1990 (green), 1993–2010 (blue); (h) 1900–1999 (green), 1993–2009 (blue); (i) 1900–2009; ( j) 1901–1990 (green), 1993–2009 (blue); (k) 1992–2010; (l) 1993–2010; (m) 1904–2003; (n) 1880–1990. From Horton et al. (2018)[4]. While rates of GMSL have changed over time, there has been an unambiguous rise in sea level over time, as measured by tide gauges and satellites (see figure 3). Figure 3 – Changes in global mean sea level from 1880 – 2014. Sea level variations are caused by a variety of natural and human-caused factors. While land mass movements and ocean circulation patterns influence sea levels, human-induced climate change is accelerating the rate of sea level rise[5]. Specifically, greenhouse gas emissions have increased global temperatures, causing ice sheets to melt and oceans to thermally expand. For example, one study found that the rate of sea level rise since 2000 resulting from the expansion of seawater as it warms “is significantly greater than at any moment in the twentieth century.”[2] Scientists’ Feedback: Thomas Frederikse Postdoctoral researcher, Jet Propulsion Laboratory/California Institute of Technology: This text cherry-picks two trend estimates of global sea levels (one number from 1900-2018 and one number from 1958-2014) to ‘show’ there’s no acceleration in global sea level since 1900. That is false. Global sea levels have accelerated since 1900, something that the authors could have calculated themselves by fitting a second-order polynomial through the time series of global sea level, which are publicly available. That simple calculation gives a significant and positive acceleration in global sea level of 0.012 +/- 0.004 mm yr-2 over 1900-2018. Instead, the article just takes two numbers and draws conclusions without looking into the actual numbers. The article also discusses the lack of direct correlation between CO2 emissions and global sea levels, due to the above-average rates of sea level and glacier mass loss in the 1930s. This is an oversimplification of the physics behind global sea levels, since many more processes than just CO2 affect global sea levels. As a result, such a clear correlation is not expected. For example, the above-average rate around ~1930 can be traced down to regional heatwaves in the Arctic region, causing a lot of ice melt[3], while a large part of the slowdown in the rate of global sea-level rise can be tracked down to retention of water behind newly-constructed dams[6]. In conclusion, this article cherry-picks numbers to claim there’s no acceleration in global sea level. Benjamin Horton Professor, Earth Observatory of Singapore: A review paper I wrote shows that for every paper that calculated present day sea level rise there is a clear increase in rate[4]."
https://science.feedback.org/review/scientific-studies-established-clear-links-between-human-caused-increased-in-atmospheric-co2-and-global-warming-patrick-moore/,Incorrect,"Instagram, Patrick Moore, 2020-12-16",“It’s a good thing that we are putting some more carbon dioxide in the atmosphere. The scientific method has not been applied in such a way as to prove that carbon dioxide is causing the Earth to warm.”,,"Incorrect: Scientific studies find that human-caused increases in atmospheric CO2 levels and other greenhouse gases are the primary driver of global warming. Flawed reasoning: Increased atmospheric CO2 levels increased plant growth in some regions of the world, but the argument that CO2 is not harmful to the planet because it facilitates plant growth is flawed. Human-caused increases in atmospheric CO2 can negatively affect natural ecosystems and human society by causing global warming, ocean acidification, and sea level rise. ","Atmospheric CO2 levels have increased by 47% since 1850, due to agricultural development, the burning of fossil fuels, and other human activities. Since 1950, approximately 100% of the global warming trend is attributed to increased CO2 emissions. Although CO2 has increased plant growth in some regions of the world, it can also negatively impact natural ecosystems and human societies.","“It’s a good thing that we are putting some more carbon dioxide in the atmosphere.  If we bring it up to a higher level than it is today, we will get, immediately, an increase in the growth of crops and trees, which is not a bad thing. The scientific method has not been applied in such a way as to prove that carbon dioxide is causing the Earth to warm.”","1 – IPCC (2014) Climate Change 2014: Summary: for Policymakers. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. 2 – Shakun et al. (2012) Global warming preceded by increasing carbon dioxide concentrations during the last deglaciation. Nature. 3 – Feldman et a. (2015) Observational determination of surface radiative forcing by CO2 from 2000 to 2010. Nature. 4 – Friedlingstein et al (2019) Global carbon budget 2019. Earth System Science Data. 5- Zhu et al. (2016) Greening of the Earth and its drivers. Nature Climate Change. 6 – Wuebbles et al. (2017) Executive summary. In: Climate Science Special Report: Fourth National Climate Assessment, Volume I. 7- Moore et al. (2017) New science of climate change impacts on agriculture implies higher social cost of carbon. Nature. 8- De Graaff et al. (2006) Interactions between plant growth and soil nutrient cycling under elevated CO2: a meta-analysis. Global Change Biology. 9 – Doney et al (2009) Ocean acidification: The other CO2> problem. Annual Review of Marine Science. 10 – Mbow et al. (2019) IP Food Security. In: Climate Change and Land: an IPCC special report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems. IPCC report. 11 – Harries et al. (2001) Increases in greenhouse forcing inferred from the outgoing longwave radiation spectra of the Earth in 1970 and 1997. Nature.","Review: These claims appeared in a video featuring Patrick Moore, an industry consultant, which has received more than 13,000 views since it was published on Instagram in December 2020. Contrary to what is claimed, the scientific evidence clearly demonstrates a causal link between atmospheric CO2 concentrations and global warming[1-4]. Furthermore, although carbon dioxide can increase plant growth in some environments, it can also negatively impact natural ecosystems and human societies by causing global warming, imbalancing the carbon cycle, and driving weather extremes[1,4,5]. Pre-industrialization atmospheric CO2 levels were around 280 parts per million (ppm)[1]. Since 1950, the burning of fossil fuels, agricultural development, and other human-caused land-use changes have led to steady increases in atmospheric CO2. Today, atmospheric CO2 exceeds 400 ppm (see figure below). Figure—The Keeling Curve, a daily record of global atmospheric CO2, shows relatively stable CO2 concentrations from 1700 to 1950, as measured by ice-cores. After 1950, CO2 concentrations rose rapidly from 300 to over 400 ppm, as measured at the Mauna Loa Observatory. From Scripps Institute of Oceanography. Alongside these increases in atmospheric CO2, global land and ocean temperatures have steadily increased (see figure below). Figure—Global temperature anomaly data relative to the 20th century average temperature from the Global Historical Climatology Network-Monthly data set and International Comprehensive Ocean-Atmosphere Data Set. These data sets show consistent global warming trends. From NOAA. As stated in a 2014 IPCC report, “Anthropogenic greenhouse gas emissions have increased since the pre-industrial era, driven largely by economic and population growth, and are now higher than ever. This has led to atmospheric concentrations of carbon dioxide, methane and nitrous oxide that are unprecedented in at least the last 800,000 years. Their effects, together with those of other anthropogenic drivers, have been detected throughout the climate system and are extremely likely to have been the dominant cause of the observed warming since the mid-20th century.”[1] And the 2017 US National Climate Assessment states, “This assessment concludes, based on extensive evidence, that it is extremely likely that human activities, especially emissions of greenhouse gases, are the dominant cause of the observed warming since the mid-20th century. For the warming over the last century, there is no convincing alternative explanation supported by the extent of the observational evidence.”[6] An analysis of the factors that influence global surface temperatures found that anthropogenic increases in greenhouse gas emissions account for more than 100% of the warming trends observed since 1850 (see figure below). Figure—The estimated role of different factors influencing global surface temperatures from 1850 to 2017. Observed temperatures are shown in black dots. Global warming over the past 150 years was primarily driven by greenhouse gas emissions (red). From Carbon Brief. While increased levels of CO2 have increased plant growth in some regions of the world, these effects also decrease with increasing CO2 concentrations[7]. In addition to CO2, plants require water and other nutrients to grow. Scientific studies show the effects of CO2 on plant growth depend on the availability of other nutrients, such as phosphorus and nitrogen[8]. The plant growth benefits of CO2 can also be outweighed by negative climate impacts, such as increasing water stress, heat stress, and ocean acidification[9,10]. In order to assess the overall impact of CO2 on the planet, all known effects of CO2 on land ecosystems and human societies should be evaluated together. Scientists’ Feedback: [Comment from a previous evaluation of a similar claim.] First, greenhouse gases are well studied, and their properties are nonnegotiable: They absorb and re-emit longwave radiation, whether they’re in a laboratory setting or in the real atmosphere. To back this up with historical evidence, scientists have known since the 1860s that CO2 is a greenhouse gas and since the 1890s that this will affect the heat budget of the Earth through warming. Even then, these claims were based on empirical evidence, and they’re supported by decades of laboratory research. Second, the link between increased greenhouse gas concentrations and warming continues to be supported by research in the last two decades. One study from 2001 used satellites to measure the type of energy entering and exiting Earth’s atmosphere and concluded that increases in greenhouse gases were responsible for extra heat measured between 1970 and 1997[11]. The authors state that their results “provide direct experimental evidence for a significant increase in the Earth’s greenhouse effect that is consistent with concerns over radiative forcing of climate.” (Here, the term “radiative forcing” refers to the extra energy trapped in the atmosphere by greenhouse gases, cause warming.) A more recent study arrived at similar conclusions, confirming predictions of the greenhouse effect in Earth’s atmosphere and providing “empirical evidence of how rising CO2 levels … are affecting the surface energy balance.”[3] In other words, rising CO2 was linked directly to warming, even when things like plant uptake of CO2 were considered. [Comment from a previous evaluation of a similar claim.] The primary empirical evidence that greenhouse gasses cause global warming is the absorption (as a function of wavelength of radiation) of gasses like CO2, CH4 and N2O. This was discovered in 1859 by John Tyndall and has become a part of fundamental physics. Anyone can check this empirical relationship at any time with an absorption spectroscopy device. The empirical evidence that increases in greenhouse gas concentrations (from fossil fuel burning) are the primary cause of century-scale warming is that observed global temperatures have risen in line with what would be expected from the observed increase in greenhouse gas concentrations and observations of natural drivers of climate change (e.g. solar output and volcanic eruptions) indicate that natural drivers are not causing warming. [Comment from a previous evaluation of a similar claim.] This is the usual misleading argument that if CO2 is good for plants, it cannot be bad for the climate. CO2 is needed for plant growth (along with water, nutrients, and energy from the sun)—but it does not change the fact that CO2 is a greenhouse gas. It increases the radiative forcing of the planet and leads to warming, as observed over the last century[5]. [Comment from a previous evaluation of a similar claim.] CO2 is indeed fundamental for most life on Earth. Plants need CO2 to grow and they are at the base of the food chain. However, this fact is often abused to claim that increasing CO2 concentrations is mainly a good thing. Although plant growth is often stimulated by increasing CO2 concentrations, CO2 also causes ocean acidification and warms the planet, thereby generating a cascade of effects from melting of glaciers and sea level rise to altered precipitation patterns and increasing frequency and intensity of extreme weather events such as heatwaves and droughts[1,9,10]. These in turn threaten water and food supplies, and as climate change progresses, this is also likely to undo much of the beneficial effect that CO2 has on plant growth[10]."
https://science.feedback.org/review/the-clothing-industry-produces-3-to-10-of-global-greenhouse-gas-emissions-as-accurately-claimed-in-patagonia-post/,Accurate,"Instagram, Patagonia, 2020-11-30",“The clothing industry contributes up to 10% of the pollution driving the climate crisis.”,,"Accurate: Scientific studies and analytical reports from the United Nations and charitable organizations estimate that the fashion industry contributes 3 to 10% of global greenhouse gas emissions.  Lacks specifics: The claim does not specify the type of pollution the fashion industry is contributing to nor the source of this information. However, it likely refers to greenhouse gas emissions, primarily CO2, that drive climate change.  ","Globally, the fashion industry is estimated to contribute 3 - 10% of the greenhouse gas emissions that are causing climate change, based on scientific studies and reports from the United Nations and charities. The clothing industry has a variety of other environmental impacts, including intensive water use, water pollution through dying and textile production, and pesticide and herbicide pollution through the agricultural production of cotton. Microplastics, which are shed primarily from synthetic textiles during washing, are also polluting the oceans, potentially negatively impacting human health and natural ecosystems.",“The clothing industry contributes up to 10% of the pollution driving the climate crisis.”,"1 – Hertwich and Peters (2009) Carbon Footprint of Nations: A Global, Trade-Linked Analysis. Environ. Sci. Technol. 2 – Ivanova et al. (2015) Environmental Impact Assessment of Household Consumption. Journal of Industrial Ecology. 3 – Chen and Burns (2006) Environmental Analysis of Textile Products. Clothing and Textiles Research Journal. 4 – De Falco et al. (2019) The contribution of washing processes of synthetic clothes to microplastic pollution. Scientific Reports. 5 – Ivar do Sul and Costa (2013). The present and future of microplastic pollution in the marine environment. Environmental Pollution. 6 – Fischedick et al. (2014) Industry. In: Climate Change 2014: Mitigation of Climate Change. Contribution of Working Group III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. 7 – Huang et al. (2016) Energy-related GHG emissions of the textile industry in China. Resources, Conservation and Recycling. 8 – Boucher and Friot (2017) Primary Microplastics in the Oceans: A Global Evaluation of Sources. IUCN. 9 – Mair et al. (2016) Global inequities and emissions in Western European textiles and clothing consumption. Journal of Cleaner Production. 10 – Ivanova et al. (2017) Mapping the carbon footprint of EU regions. Environmental Research Letters.","Review: The claim appeared in an Instagram post published by the clothing company Patagonia in late November 2020, and has received more than 502,000 views. Although the post does not indicate the source of the claim, scientific studies estimate that clothing contributes 3 to 10% of greenhouse gas emissions that drive climate change[1,2]. In addition, clothing production and use causes water pollution, pesticide pollution, and the release of microplastics into the ocean that can negatively impact human health and natural ecosystems[3-5]. The environmental impact of clothing has increased since 2000, primarily due to the rise of “fast fashion,” which refers to the production of inexpensive, rapidly produced clothing that follows the latest fashion trends. As described in a 2014 IPCC report, “during the period 2000–2005, the advent of ‘fast fashion’ in the UK led to a drop in prices, but an increase in sales equivalent to one third more garments per year per person with consequent increases in material production and hence industrial emissions.”[6] In 2017, the Ellen MacArthur Foundation, a charitable organization in the UK, published a report exploring the environmental impact of the fashion industry based on analyses from McKinsey & Company and contributions from more than 100 experts at academic institutions and in the fashion industry. While not a peer-reviewed publication, the report found that clothing sales doubled from 2000 to 2015, whereas the average number of times a garment is worn decreased by 36% (see figure below). Figure—Global clothing sales and utilization from 2000 to 2015. From the Ellen MacArthur Foundation A new textiles economy: Redesigning fashion’s future (2017). Numerous scientific studies have estimated the greenhouse gas emissions (GHG) attributed to clothing and the fashion industry. For example, a study evaluating the carbon footprint of individuals in various nations found that clothing contributed 1 to 6% to the per capita GHG footprint in 70 countries in 2001[1]. In Hong Kong, clothing contributed 28% to per capita GHG[1]. A 2015 study found that clothing consumption in European households contributed 3.5% of the carbon footprint, 4.3% of the land footprint, 4.7% of the material footprint, and 5% of the water footprint in 2007 (see figure below)[2]. Figure—Contribution of clothing and other factors to the carbon (orange), land (green), material (yellow), and water (blue) footprint of EU households. Contributions to the environmental footprint, the quality of products bought (expenditure per capita), and the footprint intensity. From Ivanova et al. 2015[2]. Another study that analyzed the environmental impact of the textile industry in China found that it contributed 4 to 8 billion tons of GHG from 200 to 2011 (see figure below), and estimated a contribution of 18.5 billion tons of GHG emissions in 2020[7]. Figure—Textile production and GHG emissions from various energy sources for the textile industry in China. From Huang et al. (2016)[7]. Some sources, including the Ellen MacArthur Foundation report and the United Nations Environment Programme (UNEP), estimate the global fashion industry contributes 1.2 billion tonnes of CO2 equivalent or 8 to 10 percent of global carbon emissions. In addition to GHG emissions, the fashion industry has been linked to a variety of other environmental impacts, including intensive water and pesticide use as well as pollution to water, air, and soil[3-6]. As described in a report from the UNEP, “The fashion industry is the second-biggest consumer of water and produces 20 per cent of global wastewater.” For instance, a single pair of jeans consumes 3,781 liters of water, according to a Levi Strauss & Co. life cycle assessment. Clothing also contributes to global microplastic pollution in the ocean, primarily through the washing process. One study estimates that synthetic clothing contributes 35% of microplastic pollution in oceans, with approximately 124 to 308 mg released for each kg of washed fabric[4]. An IUCN report, estimates that synthetic textiles consume 42,534 kilotons of plastic each year, a portion of which end up in the ocean[8]. Additional waste from the fashion industry occurs when clothes are discarded or incinerated. According to the Ellen MacArthur report, only 13% of clothes are recycled and less than 1 percent are recycled into new clothing. In contrast, the report estimates that 73% of clothing goes to landfills or is incinerated (see figure below). Figure—The global material flow of clothing in 2015. From the Ellen MacArthur Foundation A new textiles economy: Redesigning fashion’s future (2017). In addition to environmental impacts, the fashion industry also impacts human health and wellbeing. For example, a 2016 study found the demand for clothing and textiles often depends on low-cost labor, primarily in Brazil, Russia, India, and China[9]. Overall the claim, “the clothing industry contributes up to 10% of the pollution driving the climate crisis” is accurate, as it falls within 1 to 10% range of estimates for GHG emissions in scientific studies and organization reports. In addition, clothing production and consumption can be an energy- and water-intensive process that causes water pollution, microplastic release, and human health impacts. Scientists’ Feedback: Simon Mair Lecturer, University of Bradford: I’d say this is accurate. Typically studies put clothing between 3-10% of greenhouse gas emissions. There’s a brief write up of this in my thesis (section 2.3.3 page 42-43). This is aging now, but I see no reason the core estimates would have changed. This slightly more recent paper also puts clothing in the same range[9]. Ten percent is probably at the higher end of estimates, but still has a solid basis in the science. The issue with carbon footprint estimates is that they are very sensitive to different assumptions, methods, and/or data, so a 10% range is probably within an acceptable margin of error. Chris K. Y. Lo Associate Professor, The Hong Kong Polytechnic University: The claim [that the fashion contributes] up to 10% [of pollution driving the climate crisis] is not very far from the United Nations’ research estimate, which is 8%. Elisa Tonda, Head of the Consumption and Production Unit at the UN Environment Programme (UNEP), one of the 10 UN bodies involved in the Alliance, explained the urgency behind its formation in a UN News article: “The global production of clothing and footwear generates 8% of the world’s greenhouse gas emissions and, with manufacturing concentrated in Asia, the industry is mainly reliant on hard coal and natural gas to generate electricity and heat. If we carry on with a business-as-usual approach, the greenhouse gas emissions from the industry are expected to rise by almost 50% by 2030.” However, I have no access to the UN environment programme original report to confirm how this number was calculated. There is a more recent claim from our field that was published in a report authored by McKinsey & Company and Global Fashion Agenda, which estimates the fashion industry contributes roughly about 4% of the global emission. From a study that investigated the total emission of fashion and textiles production in China, the figure is even higher, assuming that China is responsible for 40 to 50% of global fashion and textiles production over the past 10 years[7]. This study projected the GHG emissions based on China’s government electricity, and combustion data using different energy sources. The China textile industry (50% of global production) is at 18.486 billion CO2 tons in 2020. This figure is surprisingly high. If it’s true, the global fashion and textiles GHG emission would be around 18.46 billion tons doubled, which is 36.9 billion tons in the best case scenario, which is close to 10 times higher than the 2nd source stated. Based on the energy consumption of textiles and fashion production in China, the pollution is very serious. The annual GHG pollution composition is just the tip of an iceberg. The microplastic problem causing water pollution is accumulating, and the negative effects to our ecosystem and human health is long lasting. It is far more devastating than GHG emission in a particular year."
https://science.feedback.org/review/brush-rake-attachments-are-primarily-used-to-pile-up-heavy-forest-debris-as-part-of-active-thinning-harvesting-and-removal-projects/,Misleading,"Facebook, Facebook users, 2018-11-21",“this is [...] a brush rake. It's used for clearing underbrush and debris from the forest floor that builds up and creates fuel for wild fires. Now you can stop looking stupid trying to make fun of Trump telling California to rake the forest.”,,Misleading: Brush rakes mount to the front of machines and are used to pile up heavy woody debris that accumulates after blow down events or as part of active timber harvesting or thinning projects. They are not used throughout forests across the U.S. to broadly perform fuel removal.,"Brush rakes are attachments for the front of a wheeled or tracked machines that are used to push woody debris and large vegetation into piles. They are typically used as part of active, labor-intensive thinning, harvesting, removal, and restoration projects—not to rake large areas or clear live brush.",“this is what the United States Department of Agriculture Forestry Service calls a brush rake. It's used for clearing underbrush and debris from the forest floor that builds up and creates fuel for wild fires. Now you can stop looking stupid trying to make fun of Trump telling California to rake the forest.”,,"Review: The claim appeared alongside the photo below in a Facebook post that was published in November 2018 and recently shared widely on the platform. To date, the post was shared 84,000 times, according to the social media analytics tool CrowdTangle. The post states, “this is what a United States Department of Agriculture Forestry Service calls a brush rake. It’s used for clearing underbrush and debris from the forest floor that builds up and creates fuel for wild fires.” A brush rake is an attachment for the front of a wheeled or tracked machine that is used to push woody debris and large vegetation into piles. According to the USDA Forest Service, raking is “the process of pushing slash or residues into piles, generally windrows, with a brush rake or a towed rake implement.” In forestry, slash and residues refer to woody debris that are left in the forest after a logging or timber harvesting event. Brush rakes are typically used in active thinning, harvesting, and reforestation projects, as the USDA Forest Service described in an email to Climate Feedback: “Brush rakes are attachments, usually on bulldozers but can also be attached to smaller skid-steers or even rubber tired tractors. In Hazardous Fuels work they are typically used to create machine piles when there is very heavy fuel loading such as after a blow down event or after timber harvest or thinning where there is a lot of large, woody material on the ground; they can move the material into piles or windrows so they can be disposed of later, usually by burning the piles. Unlike a standard blade that would also move the soil, the brush rake mostly just moves the vegetation and while the machinery does disturb the soil, it does a better job of not removing the soil than using a conventional blade. Leaving the soil on site is critical for replanting or reseeding in areas where reforestation is desired.” While the post might imply that brush rakes are used throughout forests across the country to clear woody debris, their use is limited depending on the terrain and vegetation type. As the reviewer describes below, brush rakes are often used in the southeastern U.S. to clear rapidly growing hardwood trees. In contrast, it is difficult to use brush rakes to manage fuel loads in some regions of the western U.S. where the topography is steep and the vegetation differs. As Christine McMorrow, Resource Management Communications for CALFIRE stated in an email to Climate Feedback, “Brush rakes are used to remove brush to both prepare for reforestation, but also to reduce fuels. They aren’t used much on the fireline, but I’ve seen them around. They have a role and can be useful in very brushy areas. CAL FIRE has a few that are used in the Southern Region.” Overall, the post accurately refers to the attachment as a brush rake, but misrepresents the contexts in which it is most often used and incorrectly implies that it could be used to significantly reduce fuel loading across California. Scientists’ Feedback: Malcolm North Research Ecologist, US Forest Service: The picture is of a brush rake attachment on the front of a D4 Caterpillar tractor, which is used to reduce fuels in the SE US (the reason why it’s pictured amongst longleaf pine). It doesn’t get much use in the western U.S., including California, because the topography is generally steeper (limiting where it can operate) and fuels are different in the SE where rapid regrowth, particularly of hardwoods, means you need something that can comb and rip the regrowth out. In the western U.S., brush rakes are a tool commonly used in the construction of fire lines, where the litter and duff are raked away to expose mineral earth. It’s called a McLeod rake. In sum, the mental picture and definition of a brush rake differs between the southeastern and western US, in part because fuels are different and because of operational constraints."
https://science.feedback.org/review/guardian-article-on-arctic-methane-emissions-lacks-important-context-jonathan-watts/,-1,"The Guardian, by Jonathan Watts, on 2020-10-27.",,"""'Sleeping giant' Arctic methane deposits starting to release, scientists find""",,,,"1-McGinnis et al. (2006) Fate of rising methane bubbles in stratified waters: How much methane reaches the atmosphere?, Journal of Geophysical Research: Oceans 2-Wallmann et al. (2018) Gas hydrate dissociation off Svalbard induced by isostatic rebound rather than global warming, Nature Communications 3-Saunois et al. (2020) The Global Methane Budget 2000–2017, Earth System Science Data 4-Jackson et al. (2020) Increasing anthropogenic methane emissions arise equally from agricultural and fossil fuel sources, Environmental Research Letters 5-Westbrook et al. (2009) Escape of methane gas from the seabed along the West Spitsbergen continental margin, Geophysical Research Letters 6-Berndt et al. (2014) Temporal Constraints on Hydrate-Controlled Methane Seepage off Svalbard, Science 7-Kretschmer, et al. (2015) Modeling the fate of methane hydrates under global warming, Global Biogeochemical Cycles 8-Archer (2015) A model of the methane cycle, permafrost, and hydrology of the Siberian continental margin, Biogeosciences 9-Steinle et al. (2015) Water column methanotrophy controlled by a rapid oceanographic switch, Nature Geoscience 10-Mau et al. (2017) Widespread methane seepage along the continental margin off Svalbard – from Bjørnøya to Kongsfjorden, Scientific Reports 11-Lund Myhre et al. (2016) Extensive release of methane from Arctic seabed west of Svalbard during summer 2014 does not influence the atmosphere, Geophysical Research Letters 12-Pohlman et al. (2017) Enhanced CO2 uptake at a shallow Arctic Ocean seep field overwhelms the positive warming potential of emitted methane, PNAS 13-Shakhova et al. (2014) Ebullition and storm-induced methane release from the East Siberian Arctic Shelf, Nature Geoscience 14-Thornton et al. (2020) Shipborne eddy covariance observations of methane fluxes constrain Arctic sea emissions, Science Advances 15-Berchet et al. (2016) Atmospheric constraints on the methane emissions from the East Siberian Shelf, Atmospheric Chemistry and Physics 16-Tohjima et al. (2020) Estimation of CH4 emissions from the East Siberian Arctic Shelf based on atmospheric observations aboard the R/V Mirai during fall cruises from 2012 to 2017, Polar Science 17-Thornton, et al. (2016) Methane fluxes from the sea to the atmosphere across the Siberian shelf seas, Geophysical Research Letters 18-Christensen et al. (2019) Tracing the climate signal: mitigation of anthropogenic methane emissions can outweigh a large Arctic natural emission increase, Scientific Reports","Reviewers’ Overall Feedback: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Frans-Jan W. Parmentier Associate Professor, Lund University & University of Oslo:This article’s claim that methane deposits in the Arctic Ocean are starting to be released, awakening a “sleeping giant”, cannot be supported by the limited observational data. Besides, even if these newly found seeps are increasing, they are located too deep in the ocean to have a significant impact on the concentration of methane in the atmosphere. First of all, a newly discovered source is not the same as a changing source. Second, these findings are not unexpected nor the first of their kind in the Arctic. Gas hydrates are commonly found along continental slopes at depths where high pressures and low temperatures allow for their existence. The presence of hydrates to the west of high-arctic Svalbard is well-known[5]. These hydrates have been studied extensively and occur at a similar depth as the recent findings reported by the Guardian. This makes for an ideal comparison to understand what’s going on in the Laptev Sea. The gas hydrates near Svalbard have been venting methane for at least 3,000 years, induced by geological processes rather than global warming[2], while methane release varies with the seasons[6]. Similar processes may be at play for the gas hydrate deposits found in the Laptev Sea. This underlines the need to monitor methane seeps over a long time period before rushing to the conclusion that they are increasing due to recent climate change. Model studies show that the impact of climate change on gas hydrates will be a slow process, over timescales from centuries up to a millennium[7,8]. Most importantly, the ocean is an efficient filter for methane when the water is more than 100 m deep[1]. When bubbles rise up towards the surface, methane quickly dissolves into the ocean water and is removed through oxidation[1,9]. Since the hydrates near Svalbard and in the Laptev Sea are located below a depth of 300 m, they are unlikely to influence atmospheric concentrations—even when they start to destabilize. Although the article in the Guardian acknowledges that most methane dissolved into the ocean water, the researchers also report that “methane levels at the surface were four to eight times what would normally be expected and this was venting into the atmosphere”. Elevated methane levels are not uncommon in the ocean, also near Svalbard[9]. More than a thousand gas seeps have been documented along the coast of Svalbard[10] (just six were reported by the recent expedition in the Laptev Sea). Despite the widespread release of methane into the ocean off the coast of Svalbard and extensive monitoring with land-based, ship-based and airborne methods, no significant impact on the atmosphere has been found[11]. In fact, the small amount of methane that is released at hotspots is offset by an enhanced uptake of CO2 in the same area[12]. It should be noted that the researchers interviewed by the Guardian have previously suggested very high emissions from the shallower parts of the Laptev Sea and nearby seas[13], where methane can escape to the atmosphere in larger quantities. However, three independent studies that tried to confirm those results showed that those estimates were overestimated by about a factor of five[14,15,16]. While high methane concentrations have been detected near seeps in the Laptev Sea[17], these elevated concentrations are highly localized, which makes them less important at the regional scale[14]. The article in the Guardian grossly exaggerates a small source that is unlikely to increase, while using frightening metaphors of the awakening of a “sleeping giant”. This draws attention away from genuine feedbacks in the Earth system such as the release of carbon from permafrost thaw, the deterioration of global ecosystems, and the rapid loss of sea ice. Anthropogenic methane emissions are roughly 50 to 70 times larger than emissions from the Arctic Ocean, and we can compensate for Arctic methane release by reducing anthropogenic emissions with present-day technology[18]. That’s the real giant that we can and should tackle, rather than hypothetical sea monsters. Ben Poulter Research Scientist, NASA:The article claims that frozen methane, stored in ocean sediments in the Arctic, has become destabilized and is being emitted to the atmosphere. The article generally overlooks the fact that 1) the methane emitted from the sediments does not escape to the atmosphere because it is oxidized in the water column, 2) the methane fluxes the research crew are measuring have been detected in previous cruises and are not an indicator of a rapid change, and 3) this work has been disputed previously through independent studies using atmospheric, or top-down, constraints to measure the Arctic methane budget. Paul Overduin Senior Scientist, Alfred Wegener Institute:The words “starting” and “triggering” tacitly assume that the beginning of a process was observed (i.e., that has not taken place until now). The article provides no evidence to support this assumption. “Triggering” connotes a small impulse leading to an explosive result—this word choice is not neutral, but highly suggestive. The article then softens the claim of a new release/source relevant to climate: “…most of the bubbles were currently dissolving…”, “…findings were preliminary” and “…will not be confirmed until they return”. The article then goes on to contradict the assumption of “starting”: methane emissions have been observed before (“the third source of methane emissions from the region”, “previously reported the gas is being released”, “second year in a row”). No differentiation is provided between previous and current observations. Important context is omitted: such methane emissions are observed at many locations on Arctic slopes and could be expected at this location. Currently, Arctic methane sources are a small contribution to atmospheric methane. The source of the methane observed in this story is of central importance in judging whether it is sensitive to climate change or likely to be large enough to affect climate. Only one mention of the source is made: “gas hydrate”, without any background. This is a very understudied part of a region that is most strongly affected by climate change. It is tremendously challenging for science to fund research and every new observation is of value and should be analyzed thoroughly and soberly, in context. David Archer Professor, University of Chicago:Putting these new methane emissions into a global context, they are much smaller than emissions fluxes from tropical wetlands, the main natural source. This means that unless Arctic methane fluxes blow up by a factor of 100 or more, they won’t play a huge role in global warming. I was relieved by the first quote in the article, beginning “At this moment, there is unlikely to be any major impact on global warming…,” but I was less happy with a later quote, “Potentially they can have serious climate consequences, but we need more study before we can confirm that.”"
https://science.feedback.org/review/sea-ice-loss-due-to-climate-change-is-the-biggest-threat-to-polar-bear-survival-and-has-already-led-to-declines-in-some-polar-bear-subpopulations-contrary-to-climate-realism-video-m/,Misleading,"Climate Realism, Heartland Institute, Andy Singer, 2020-10-23"," “In 1950, there were around 10,000 polar bears globally. Today, polar bear populations are near 39,000. Polar bear populations are increasing dramatically as the planet has warmed.”",,"Factually inaccurate: The current global polar bear population is estimated to be 20,000 to 26,000 bears distributed among 19 subpopulations, not 39,000 as claimed.  Fails to grasp significance of observation: Polar bears were heavily harvested in the 1950s and 1960s. An increase in polar bear population size since the 1950s does not demonstrate that polar bears are not affected by climate change, but rather that an agreement was signed in 1973 stating that harvesting should be done at sustainable levels. Inadequate support: There is no scientific evidence provided to support the claims made in the video or the figure showing increases in the global polar bear population size over time.","Loss of sea ice habitat caused by climate change is the most important threat to the long term survival of polar bears. Of the 19 subpopulations of polar bears, two have already experienced declines due to losses in sea ice. It is difficult to estimate trends in the global polar bear population; however, trends at the subpopulation level from 2019 show that four subpopulations declined, five were stable, and only two increased.","“In 1950, there were around 10,000 polar bears globally. Today, polar bear populations are near 39,000. That alone pokes a hole in the whole plight of the polar bears story. Polar bear populations are increasing dramatically as the planet has warmed.”","1 – Stirling et al (2012) Effects of climate warming on polar bears: a review of the evidence. Global Change Biology. 2 – Stern et al (2016) Sea-ice indicators of polar bear habitat. The Cryosphere. 3 – Regehr et al (2016) Conservation status of polar bears (Ursus maritimus) in relation to projected sea-ice declines. Biology Letters. 4 – Bromaghin et al (2015) Polar bear population dynamics in the southern Beaufort Sea during a period of sea ice decline. Ecological Applications. 5 – Lunn et al (2016) Demography of an apex predator at the edge of its range: impacts of changing sea ice on polar bears in Hudson Bay. Ecological Applications. 6 – Wiig et al (2015) Ursus maritimus. The IUCN Red List of Threatened Species. 7 – Derocher et al (2013) Rapid ecosystem change and polar bear conservation. Conservation Letters. 8- Harvey et al. (2017) Internet blogs, polar bears, and climate-change denial by proxy. BioScience. 9 – Hunter et al (2010) Climate change threatens polar bear populations: a stochastic demographic analysis. Ecology. 10 – Molnar et al. (2020) Fasting season length sets temporal limits for global polar bear persistence. Nature Climate Change. UPDATES: 30 October 2020: This post was updated to include additional comments from Ian Stirling.","Review: The claims appeared in a Facebook video published in October 2020 by “Climate Realism”, a project run by the Heartland Institute, which has a history of publishing climate information inconsistent with findings from the scientific community. The video suggests that global warming is not a threat to polar bears because the global polar bear population increased in size since 1950. Contrary to this claim, scientific evidence demonstrates that sea ice loss induced by climate change is currently the greatest threat to the long-term survival of polar bears[1-3]. Polar bears rely on sea ice to hunt seals (their primary prey), mate, establish dens, and move to new regions seasonally[2]. Loss of sea ice is occurring in almost all polar bear subpopulations. Scientists can evaluate the effects of climate change on polar bears by correlating local losses in sea ice habitat with polar bear subpopulation size. Several studies using this approach found that loss of sea ice has already negatively affected some subpopulations, including Western Hudson Bay and Southern Beaufort Sea (see figure below)[4,5].Figure—Estimated size of the Western Hudson Bay polar bear subpopulation using data from capture-recapture models from 1984-2011. From Lunn et al. 2016[5]. In addition to declines in population size, loss of sea ice also affects polar bear body condition and survival rates. “Long-term monitoring studies in Canada suggest that polar bear body condition, survival and population growth rates are all negatively impacted by declines in the availability of sea ice habitat and there are no data to suggest that polar bears are thriving in areas where sea ice has significantly declined,” said Gabrielle Lamontagne, a communication advisor for Environment and Climate Change Canada. The trend of the global polar bear population is unknown, according to the IUCN Red List[6], however trends can be observed at the subpopulation scale. The current global polar bear population is estimated to be 20,000 to 26,000 bears, which are distributed among 19 subpopulations[6,7]. Of the 19 subpopulations measured by the IUCN Polar Bear Specialist Group, only two increased, four declined, and five were stable in 2019. The other subpopulations did not have enough data to demonstrate short or long-term trends (see figure below). Figure—Geographic distribution, size, and trends of 19 polar bear subpopulations measured by the IUCN Polar Bear Specialist Group. Colors reflect subpopulation trends in 2019. Shape and size represent subpopulation size, measured in the number of bears. Adapted from the IUCN Polar Bear Specialist Group. These data directly contradict the video’s estimate that the global polar bear population is 39,000 bears. Although there is no scientific source cited in the video, the inaccurate number was most likely drawn from a blog published by Susan Crockford in March 2019. As stated in Harvey et al. (2018), “as of this writing, Crockford has neither conducted any original research nor published any articles in the peer-reviewed literature on the effects of sea ice on the population dynamics of polar bears.”[8] While the global polar bear population may have increased from 1950 to today, data on polar bear populations was limited or non-existent prior to the late 1970s, as described by the reviewers below. During this time, hunting, killing, and capturing polar bears were the biggest threats to their survival. In 1973, the Agreement on the Conservation of Polar Bears was signed to address these practices[7]. Specifically, Article II of the agreement states, “Each Contracting Party shall take appropriate action to protect the ecosystems of which polar bears are a part, with special attention to habitat components such as denning and feeding sites and migration patterns, and shall manage polar bear populations in accordance with sound conservation practices based on the best available scientific data.” This agreement likely led to an increase in the global polar bear population in the 1970s[9]. But as stated in Hunter et al. (2015), “there is no evidence that these increases continued, and such recoveries, where they occurred, are irrelevant to the effects of recent changes in the availability of sea ice”[9]. Overall, the claims made in the video are not consistent with scientific evidence demonstrating that loss of sea ice habitat due to climate change is the biggest threat to the long-term survival of polar bears[10]. Some subpopulations of polar bears have already declined due to losses in sea ice. The claim that the global polar bear population is 39,000 bears is unsupported and inconsistent with current evidence. Scientists’ Feedback: Andrew Derocher Professor, University of Alberta: [comment from a previous evaluation of a similar claim] There are 19 subpopulations of polar bears across the Arctic. Four are likely decreasing (according to the IUCN/SSC Polar Bear Specialist Group – of which I am a member). Five are likely stable and two are likely increasing. The remainder are unknown. If one considers the “global” population as if there is 1 population in the Arctic, the claim of “growing” cannot be supported. While we have zero data on polar bear abundance until the late 1970s, polar bears were commercially harvested until ca. 1973 when the Agreement on the Conservation of Polar Bears was signed that introduced harvest controls. Polar bears, while based on poor or no data, were heavily depleted in the 1950s-1960s. So, from 1970 to 2020, polar bear populations overall increased. This of course ignores areas that have now declined (Western Hudson Bay, Southern Hudson Bay, Southern Beaufort Sea) and M’Clintock Channel that was severely overharvested post-1973. It’s a word game. Past increases were due to harvest controls. Current declines are due to climate change associated loss of sea ice[1,2,3]. Ian Stirling Adjunct Professor, University of Alberta: First, and most importantly, there never was a factual basis for the “estimate” in 1950 as no population studies of polar bears had been done anywhere in the Arctic at that time. The number was a genuine “guestimate”, i.e., simply a guess based on what little was known before there had been any population surveys or research on the relationship between the polar bears and seals. Another important additional ecological aspect was that in 1950, no one realized how enormous the populations of ringed and bearded seals were around the circumpolar Arctic or, consequently, what their potential might be for supporting much larger populations of polar bears than were normally seen not too far offshore where some humans traveled regularly. As serious quantitative population-level surveys began in the late 1960s and early 1970s, in response to the heavy overharvesting that had taken place in several populations, mainly through the 1960s and into the early 70s. Much of this new research was facilitated by increased research budgets and the development of more effective and safer immobilization drugs which, together, made the first quantitative studies of a few populations possible. So, although no one has any factual idea about the size of the circumpolar population of polar bears in 1950, it seems pretty clear that the total guestimate of 10,000 was likely low, even in the face of heavy overharvest of some populations. However, given that there were simply no quantitative data with which to estimate population size in 1950, the only accurate statement that can be made is that we simply don’t know. [the following comment is from a previous evaluation of a similar claim] As for real numerical information on polar bears, if anyone wants to know how much can be said with as much reliability as is possible, they should go to the web site for the IUCN Polar Bear Specialists Group (which I am also a member of). Note on the left hand side there are headings that give estimates and summaries (with references) of knowledge for all the 19 populations. The estimates for some populations are labelled as current, outdated, and nonexistent for others, particularly in Russia, so it is not technically possible to have a “total estimate”. In reality, it is the status and trends of the 19 individual populations that count. Several populations, such as those in western and southern Hudson Bay, and the southern Beaufort Sea are confirmed unequivocally, from long-term data, to have declined significantly as a direct result of climate warming causing steady loss of sea ice[4,5]. Some other populations are likely also declining, just judging from the extent of the steady loss of ice but we lack long-term data with which to make that assessment, and a couple are doing OK, such as Foxe Basin and Davis Straight, and one seems to be increasing (M’Clintock Channel). However, unless we are able to stop global warming and maybe even start to cool the planet, all populations will decline severely and some will be lost forever[9,10]. The steady loss of sea ice in all subpopulation regions is well summarized by Stern and Laidre[2]. Dr. Derocher and I also published a review a few years ago that gives the state of knowledge about the effects of climate warming on polar bears[1]."
https://science.feedback.org/review/climate-change-can-make-it-harder-for-the-amazon-rainforest-to-grow-back-from-deforestation-but-that-does-not-mean-40-of-it-will-now-turn-into-a-savanna/,Imprecise,"The Guardian, Fiona Harvey, 2020-10-05",“Amazon near tipping point of switching from rainforest to savannah”,,"Misrepresents a complex reality: Some Amazon forests exist in climates that can support both savannas and rainforests. While it is possible that some Amazon forests may recover as savanna instead of rainforest after deforestation, this is a natural phenomenon that is not new.  Lacks specifics: The claim is supported by the study it is based on, but may be misunderstood by readers without sufficient context. The study describes whether a deforested area might recover as savanna rather than rainforest as climate changes. However, the study authors note in their paper that they overlook other components that may impact how a forest responds to climate change, such as the ability for trees to cope with water stress.","Some Amazon forests occur in climates that can also support savannas, and this natural phenomenon is not recent. The stability of rainforests can be influenced, in part, by the ability of trees to regulate rainfall on a regional scale. If disturbed on a large scale, then, some rainforests might regrow as savannas. Severe climate change may result in some regions in the Amazon becoming increasingly unsuitable for rainforests, while other regions are predicted to become more suitable. ","“Amazon near tipping point of switching from rainforest to savannah. As much as 40% of the existing Amazon rainforest is now at a point where it could exist as a savannah instead of as rainforest. Any shift from rainforest to savannah would still take decades to take full effect, but once under way the process is hard to reverse. Rainforests are highly sensitive to changes in rainfall and moisture levels, and fires and prolonged droughts can result in areas losing trees and shifting to a savannah-like mix of woodland and grassland.”",1 – Staal et al. (2020) Hysteresis of tropical forests in the 21st century. Nature Communications. 2 – Nepstad et al. (1994) The role of deep roots in the hydrological and carbon cycles of Amazonian forests and pastures. Nature.3 – Nepstad et al. (2007) Mortality of large trees and lianas following experimental droughts in an Amazon forest. Ecology. 4 – Balch et al. (2015) The susceptibility of Southeastern Amazon Forests to fire: Insights from a large-scale burn experiment. BioScience. 5 – Segovia et al. (2020) Freezing and water availability structure the evolutionary diversity of trees across the Americas. Science Advances. 6 – Dexter et al. (2018) Inserting tropical dry forests into the discussion on biome transitions in the tropics. Frontiers in Ecology and Evolution.,"Review: The claims appeared in an article published by The Guardian on 5 October 2020, which has received more than 65,000 interactions on Facebook according to the social media analytics tool CrowdTangle. These claims are based on a study recently published in Nature Communications, which maps potential distributions of tropical forests based on recent and severe climate change models[1]. Specifically, the Guardian article claims, “As much as 40% of the existing Amazon rainforest is now at a point where it could exist as a savannah instead of as rainforest,” which can be misleading to readers without additional context as it might imply that 40% of the Amazon rainforest is currently at a tipping point. This statement does not appear in the study the article is based on[1]. Instead, the study examines how resilient forests are to deforestation in current and future climates. In addition, this claim might incorrectly suggest that the Amazon rainforest did not have the possibility of existing as a savanna before. As described in the study, some forests in the Amazon occur in climates that can also host savannas[1]. The stability of forests is influenced by rainfall levels and the ability of forests to regulate rainfall at a regional scale through forest-rainfall feedback (see figure below). This feedback describes the process of trees extracting water from the soil and releasing it into the air through photosynthesis. When a forest is lost, the feedback is also lost, reducing rainfall. As a result, the vegetation that grows back can be different than what was present previously. Figure—The forest-rainfall feedback affects the stability of forest distributions. Under high rainfall conditions, forests are stable (green). Under intermediate rainfall, land can exist as bistable forest, where it is either forest (yellow, bottom) or non-forest (grassland or savanna; yellow, top). Under low rainfall conditions, only non-forest exists (red). At a regional scale, the forest-rainfall feedback can impact the minimal (top) and maximal (bottom) extent of the forest. From Staal et al. (2020)[1]. The study explored how rainfall and rainfall-forest feedback affect forest resilience to recent climate (2003-2014) and late 21st century climate (2071-2100) under a severe climate change scenario (SSP5-8.5). Under severe climate change, the authors found, “an area of 1.91 million km2 changes from unsuitable to suitable (i.e. either stable or bistable) for forest, whereas an area of 2.37 million km2 changes from suitable to unsuitable,” (see figure below)[1]. This means that some current forests could convert to savanna after deforestation, particularly under future climate change. The article in The Guardian notes this when it says, “They also looked at what was likely to happen if greenhouse gas emissions kept rising, and found that the ability of forests to grow back once trees were lost would be much reduced.” But other statements in the article fail to make it clear that this is contingent on a deforestation event. Figure—(a) Minimal (green) and maximal (beige) forest distributions under recent climate (2003-2014). (b) Minimal (green) and maximal (beige) forest distributions under severe climate in the late 21st century (2071-2100). (c) Changes in forest distribution between current and late 21st century climate. Red areas are suitable for stable forests under recent climate, but become unsuitable for forests in the late 21st century due to low rainfall levels. Blue areas are unsuitable for forests under recent climate, but become suitable for forests in the late 21st century due to higher rainfall levels. From Staal et al. (2020)[1]. While the Staal et al. (2020) study predicts potential changes in forest distribution in South America based on projected rainfall levels as well as rainfall-forest feedback, it also acknowledges limitations of their approach. For instance, the study does not account for other factors that might affect forest resilience to climate change, such as the ability of trees to cope with water stress, as the reviewers describe below[2-5]. The article in The Guardian also claims, “Any shift from rainforest to savannah would still take decades to take full effect, but once under way the process is hard to reverse,” and “Rainforests are highly sensitive to changes in rainfall and moisture levels, and fires and prolonged droughts can result in areas losing trees and shifting to a savannah-like mix of woodland and grassland.” While these statements might be correct, they were not explicitly explored in the study the article was based on[1]. As noted by the reviewers below, long-term experiments are needed to evaluate how the Amazon forest responds to environmental disturbances, such as low rainfall. Scientists’ Feedback: Arie Staal Researcher, Utrecht University: As much as 40% of the existing Amazon rainforest is now at a point where it could exist as a savannah instead of as rainforest. This statement is supported by our study, but it may cause misunderstanding[1]. The phrasing “is now at a point” might cause people to believe that part of the Amazon possibly existing as savanna was not the case before, and something has changed so that a transition could be imminent. That is not what we state in our study. The fact that some forests exist in a climate that can also support savanna is a natural phenomenon; while it does create the potential for large-scale switches to savanna, we don’t mean to say that 40% of the Amazon rainforest is on the brink of collapse. But again, the above statement in itself is not a false representation of our work. Any shift from rainforest to savannah would still take decades to take full effect, but once under way the process is hard to reverse. This is based on a statement that I gave to the Guardian in which I meant that in case a shift would occur at a particular location, the process would probably take a few decades. The words “full effect” might be understood as if the statement applies to large scales (such as 40% of the Amazon), which is stretching my original intention, although it could still be true. Here I should add that this statement goes beyond our present study – we did not investigate such time scales or trajectories. It is context that is based on existing (but uncertain) evidence in the literature. The second part of the sentence is fine. In summary, I would say that this statement is not false, but rather speculative. Rainforests are highly sensitive to changes in rainfall and moisture levels, and fires and prolonged droughts can result in areas losing trees and shifting to a savannah-like mix of woodland and grassland. A better phrasing would have been “Rainforests can be [highly] sensitive to…” or “Some rainforests are [highly] sensitive to…”. Other than that nuance, I consider the statement to be correct and consistent with our results. The resulting ecosystem will be distinct from natural savannas regarding biodiversity, but resemble them in structure. In short, the devil is in the detail. These claims made in the Guardian are not false, but without proper context they can be prone to misunderstanding. Daniel Nepstad Executive Director and President, Earth Innovation Institute: The statement “As much as 40% of the existing Amazon rainforest is now at a point where it could exist as a savannah instead of as rainforest” is very misleading. It implies that something has changed—that rainfall is declining across the entire Amazon—when it has not. Dry season length and air temps have increased in parts of the eastern and SE Amazon, where deforestation is concentrated. We are not seeing big reductions in rainfall over the largely forested center and west of the Amazon. The Staal et al. (2020) paper is simply pointing out something we have known for a long time. We find natural savannas (cerrados) and closed canopy forest across a large range of annual rainfall. The savannas of Alter do Chão, near Santarem (that captured international media attention last year when they caught fire) are there because of the sandy soil of that region. They are surrounded by tall, dense forests—with annual rainfall of about 2000 mm. The Staal et al. (2020) paper has left land-use and fire outside of the study and is basically saying that climate-change-driven shifts in the boundaries between savanna and closed canopy forests move slowly and are shaped by the influence of the forest itself on evapotranspiration and rainfall patterns. My own experiments have demonstrated that the Amazon forest is remarkably tolerant of drought and fire, partly because it is deeply-rooting and hard to burn[2,3,4]. Amazon forests can tap soil moisture stored to at least 12 meters depth. That is how they get through dry years. See this blog I wrote about these experiments. Luciana Alves Assistant Researcher, University of California, Los Angeles: First, I would like to say that the paper’s authors (Staal et al.) were very careful with the interpretation of their findings, always highlighting throughout the paper that the projections are a “first-order approach to provide useful insights”, and that they did not take into account other important factors affecting the distribution of tropical forests, specifically the ability of trees to cope with water stress by changing carbon allocation patterns and making adjustments to water-use efficiency due to increased CO2 and temperature. To run their models, the authors assumed all tropical forests are similar, i.e., their level of resilience to disturbance is the same, independent of distinct evolutionary histories[5], composition, and distribution of tree traits conferring resilience or resistance to strong disturbance events. Specifically, about the claim published in The Guardian piece that “As much as 40% of the existing Amazon rainforest is now at a point where it could exist as a savannah instead of as rainforest“, I believe it is an oversimplification. To be fair, I did not find that statement in the paper. Although the climatic conditions may not be stable to support rainforests, drier areas within tropical America are currently covered by tropical dry and transitional forests; most importantly, tropical dry forests actually occur in drier areas than savannas in South America[5,6]. The other claims: “Any shift from rainforest to savannah would still take decades to take full effect, but once under way the process is hard to reverse,” and “Rainforests are highly sensitive to changes in rainfall and moisture levels, and fires and prolonged droughts can result in areas losing trees and shifting to a savannah-like mix of woodland and grassland.” Yes, any shift will take decades to take effect, but it is not really clear for me why bi-stable states are not possible to be maintained in the paper’s modelling approach if one takes into account the other important factors mentioned above shaping the resilience of tropical forests. There are still open questions on the mechanisms driving changes in tropical forests in response to multiple stressors (such as climate change, fire and deforestation). Adam Pellegrini University Lecturer, University of Cambridge: The Staal et al. article raises interesting questions about the resilience (i.e., ability to recover from a disturbance) of tropical rainforests. Ultimately, however, we need experimental tests of the ability of forests to recover from extreme perturbations by drought and fire, which can take years to produce meaningful results. Consequently, we are left with much uncertainty about how tree communities may respond to a changing climate: species better equipped to tolerate drought and fire may colonize, and physiological adaptations like resprouting could assist in tree recovery (to just name a few factors). Undoubtedly trees will die in the future, and tropical forests are especially vulnerable to drought and fire; however, we know from fire experiments in savannas that when fire is excluded, forests can regrow, and they do so on the order of decades. Whether the ability of forests to regrow after fire will be hampered by climate change remains the golden question. UPDATES: 16 Oct. 2020: The details of this post were updated to clarify that the article is not misleading, but some statements could be misinterpreted by readers without additional context."
https://science.feedback.org/review/article-by-the-daily-caller-oversimplifies-drivers-of-wildfires-and-downplays-role-of-climate-change-chris-white/,-1,"The Daily Caller, by Chris White, on 2020-09-13.",,"""Wildfires Will Become Worse Thanks To Decades-Old Liberal Policies, Says Fire Expert Who Predicted Uptick In Blazes""",,,,"1 – Stephens et al. (2005) Federal forest-fire policy in the United States. Ecological Applications. 2 – Gonzalez et al. (2018) Chapter 25: Southwest. In Impacts, Risks, and Adaptation in the United States: Fourth National Climate Assessment, Volume II. 3 – Steel et al. (2015) The fire frequency‐severity relationship and the legacy of fire suppression in California forests. Ecosphere. 4 – Donato et al. (2006) Post-wildfire logging hinders regeneration and increases fire risk. Science. 5 – Abatzoglou and Williams (2016) Impact of anthropogenic climate change on wildfire across western US forests. PNAS. 6 – Williams et al. (2019) Observed impacts of anthropogenic climate change on wildfire in California. Earth’s Future. 7 – Williams et al. (2014) Correlations between components of the water balance and burned area reveal new insights for predicting forest fire area in the southwest United States. International Journal of Wildland Fire. 8 – Anderson (2006) Chapter 17: The use of fire by Native Americans in California. Fire in California’s Ecosystems. 9 – Weber et al. (2020) Spatiotemporal trends in wildfires across the western United States. Remote Sensing. 10 – Littell et al. (2018) Climate change and future wildfire in the western United States: An ecological approach to nonstationarity. Earth’s Future.11 – Turner et al. (2011) Decadal trends in net ecosystem production and net ecosystem carbon balance for a regional socioecological system. Forest Ecology and Management.","Reviewers’ Overall Feedback: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: The causes of the increase in burned area in the western US in recent decades – and the record-setting fires of 2020 – are complex, driven by a mix of a changing climate, a 100-year legacy of overzealous fire suppression in forests adapted for frequent low-level fires, more people living in highly flammable wildland urban interface areas, and at times a counterproductive role of some environmental regulations. However, this article glosses over much of this complexity, presenting a simple but misleading narrative that land management rules enacted by the Clinton administration set the stage for the destructive fires we are experiencing today. In reality, the large fuel build up we have seen in some western forests dates from well before the Clinton administration. Restrictions on logging only play a minor role, as most forests were not regularly logged and traditional logging is not a particularly effective form of fuel management. Large, mature trees are at relatively low fire risk; the problem is smaller pre-commercial trees and undergrowth that can allow fires to burn hotter and reach into the canopy of larger trees. Cutting down mature trees in many cases exacerbates the growth of denser and less fire-resistant replacement vegetation. Thinning of smaller trees, brush removal, and controlled burns are the most effective means of fuel reduction, and historically the timber industry has had little involvement in these activities. At the same time, it is quite clear that a changing climate has played a large role in increasing fuel aridity and making conditions ripe for the severe fires we are experiencing today. The recent Fourth National Climate Assessment suggested that up to half the increase in burned area since the 1980s can be attributed to changing climate conditions, and recent work finds a clear link between climate change and increased burned area in the California Sierras[2,5,6]. While some uncertainties remain, this article highlights voices that are unrepresentative of the growing consensus among both climate and wildfire scientists on the role of climate in recent wildfire activity. It is clear that we need improved forest management – more thinning of pre-commercial trees, brush removal, and controlled burns – to reduce fuel loading in western US forests and make up for the US Forest Service’s misguided legacy of fire suppression. And there are certainly cases where environmental rules have gotten in the way of effective forest management and need to be streamlined. But blaming the increase in fire activity solely on environmental regulation is a misrepresentation that minimizes other important factors and ignores the complex history of forest management in the western US. The article paints recent fires in the western US as stemming from “Liberal” legislative efforts during the 1990s to protect old forests from unsustainable logging rather than from climate change. A large body of scientific research shows that year to year variability in regional burned area is strongly affected by summer air temperatures (see figure below). Figure—Correlation between annual forest burned area and maximum daily temperature anomalies during the summer months (June, July, and August) in the southwest US from 1984-2013. Adapted from Williams et al. (2014)[7]. Rising regional temperatures exponentially increase the atmospheric vapor pressure deficit (VDP), which causes forests to become drier and more flammable, contributing to the conflagrations currently observed in the region[5]. Other factors also contribute to this current problem, such as more people living and playing in urban-proximate forests, as well as a century of fire suppression leading to fuel accumulation in dry forests with historically frequent fire[1,2]. Nevertheless, climate change is a key driver of recent increases in fire activity across the western USA[2,5,6]. This article’s focus on criticizing liberal policies in general and President Clinton in particular does not do justice to this highly complex issue. Fire suppression in western forests has been pursued in earnest for roughly a century, long predating Clinton’s terms as president. Likewise, the 1973 Endangered Species Act (protecting the spotted owl and other forest-dwelling species) was signed by a Republican president. Policymakers of all affiliations have worsened (or failed to solve) the West’s difficult wildfire problems. The article does make some valid points, such as the fact that decades of fire suppression has created a dangerous disequilibrium in western forests with massive fuel loads of crowded trees and dense brush. The article is also on the right track in mentioning that logging could have (and may yet still) play a role in reducing this fuel load. But, like most of the article, this argument is oversimplified. Logging strategies differ depending on whether the goal is profit, fire prevention, wildlife habitat, or some combination thereof. Furthermore, many of the fire-prone areas in question are too rugged and remote for any commercially viable logging operation. The article’s statements about prescribed burns are generally correct but incomplete. Prescribed burning is now (belatedly) recognized as a crucial management tool that has been underutilized due to bureaucratic obstacles and lack of incentives. Unfortunately, it is not possible to fix the problem by immediately and drastically increasing annual prescribed burn acreage. Many forests are now too dense; prescribed burns would become infernos that destroy human life and property, leaving a charred wasteland instead of a clean forest floor. Although there is no clear way out of this conundrum, fire experts are actively working on it. Native American controlled burning techniques are receiving an overdue resurgence of interest[8]. The most problematic part of the article is the climate change section. It misleadingly says that “climate change has almost nothing to do with fire kindling gathering across the forest floors.” True, but that is not the point. Climate change dries out the fuel and increases air temperatures, making fires more likely to start, more likely to spread, and more likely to reach catastrophic intensities. This seems to be what happened when the Creek Fire in Fresno County suddenly exploded into a conflagration during the record-breaking heat wave of 6 Sep. 2020. Climate change may also gradually kill trees via direct effects (temperature, drought) or indirect effects (pests, pathogens), creating an even more flammable landscape. Experts do debate the relative contribution of poor forest management vs. climate change in creating the significant positive trend in acreage burned and numbers of large fires in recent decades in the West[9]. It’s not a simple or homogenous question, because fires in some forest types are more “fuel-limited” while fires in other forest types are more “climate-limited”[3]. But most peer-reviewed studies on this topic have identified climate change as an important factor over broad swaths of Western land area and vegetation types. For example, Abatzoglou and Williams (2016) estimated that climate change has already roughly doubled the acreage of forest fires in the Western US (comparing 1984-2015 to historical background levels)[5]. This trend is expected to accelerate: Littell et al. found that by 2040, “statistical climate‐fire models project large increases in area burned,” ranging from 43% to 240%, for the large majority of Western vegetation types. (Fuel-limited vegetation types, a minority of the total, were not expected to burn more)[10]. In conclusion, this Daily Caller article addresses an important topic in a superficial way, making some reasonable arguments but glossing over important details. The dismissal of climate change as a contributing factor to Western wildfires contradicts the best available evidence and appears to be politically rather than scientifically motivated. 1) The article neglects the voluminous literature that connects increased frequency of large fires, increased area burned, and increased fire severity to climate. 2) The article focuses on one ecosystem type (seasonally dry mixed conifer forests with mixed severity fire regimes) where the impact of climate change has been exacerbated by fuel accumulation due to fire suppression, and misleadingly conflates this one factor with the increase in large fire frequency, size and severity across the region in a diverse array of ecosystems that are not affected by fire suppression in the same way. It ignores that fire is increasing throughout the region, regardless of whether it is burning in ecosystems that have been changed by fire suppression or not. Many of the largest fires that are directly impacting communities in California and around the West are not burning in these seasonally dry forests. 3) The article conflates the effects of prescribed fire with the effects of logging on fuels. It ignores the fact that past logging focused on larger diameter trees, which are more profitable, rather than the removal of small diameter trees. Removing small diameter trees while leaving large diameter mature trees can enhance seasonally dry forests’ resilience to fire and other climate change impacts, and result in greater stability of their stored carbon, but is not usually profitable without significant public subsidies. Logging that maximizes removal of the most profitable timber can increase long term fire risk[4]. 4) The article ignores the fact that spotted owls became endangered because most of their old growth habitat had already been logged over. Today, the challenge is to get mechanical fuels treatments and prescribed fire onto the landscape at scale in ways that can enhance the resilience of owls and other species’ habitat to climate change. Annotations: The statements quoted below are from the article; comments are from the reviewers (and are lightly edited for clarity). Bob Zybach Bob Zybach works at the Heartland Institute, a conservative think-tank. According to PBS Frontline, “Few entities have worked harder to instill doubt in American minds about the science of climate change than the Heartland Institute.” Those numbers dropped between 1991 and 2000 and continued dropping The drop really began around 1988 (see figure below)[11]. Figure—Annual harvest removals in the Pacific Northwest region of the US from 1985 to 2007. From Turner et al. (2011)[11].They’ve gone and left hundreds of thousands of acres of burnt timber, a fire bomb waiting to happen, standing in place The suggestion here seems to be that burned areas should have been salvage logged to reduce the risk of future fire. A seminal study from southern Oregon found that salvage logging not only reduced seedling establishment, but importantly increased fine and coarse fuels on the ground, likely increasing fire risk[4]. Zybach is not convinced. “The lack of active land management is almost 100 percent the cause,” he told the DCNF, noting that climate change has almost nothing to do with fire kindling gathering across the forest floors. Other researchers share his skepticism. This statement is misleading. While climate change might not strongly affect the accumulation of “fire kindling,” it plays a huge role in how dry and flammable forests become during summer. A recent study published in the prestigious Proceeding of the National Academy of Sciences found: “Although numerous factors aided the recent rise in fire activity, observed warming and drying have significantly increased fire-season fuel aridity, fostering a more favorable fire environment across forested systems. We demonstrate that human-caused climate change caused over half of the documented increases in fuel aridity since the 1970s and doubled the cumulative forest fire area since 1984.” Also see this for further discussion on the topic: https://www.pnas.org/content/113/42/11649. Global warming may contribute slightly Again, Abatzoglou and Williams (2016) show that “Although numerous factors aided the recent rise in fire activity, observed warming and drying have significantly increased fire-season fuel aridity, fostering a more favorable fire environment across forested systems. We demonstrate that human-caused climate change caused over half of the documented increases in fuel aridity since the 1970s and doubled the cumulative forest fire area since 1984.”[5] Fuel aridity alone can explain about 75% of the year to year variability in burned area across the West and climate change is causing large parts of the region to become more arid."
https://science.feedback.org/review/climate-change-forest-management-and-several-other-causes-contribute-to-wildfire-severity-and-total-area-burned-in-the-western-united-states/,Misleading,"Facebook, Facebook users, 2020-09-09",“Forest fires are caused by poor management. Not by climate change.”,,"Misrepresents a complex reality: The causes and behaviors of wildfires in the western US are influenced by a variety of factors, including weather conditions, climate change, past fire suppression practices, and an increase in the number of people living near wildlands.  Incorrect: Scientific studies demonstrate clear links between climate change, hotter and drier conditions, and an increase in dry vegetative fuel load, drastically increasing the amount of forest fire area in the western US.","In addition to land management practices, the severity of wildfires in the western US is influenced by extreme heat, drought, and the amount of dry vegetative fuel, which are all linked to human-caused climate change. Climate change is not the only factor that affects fire behavior, but it is an important one. Since 1984, the forest fire area in the western US likely doubled due to climate change.",“Forest fires are caused by poor management. Not by climate change. While fire behavior is affected by weather and climate...fires around the state of California do not happen because of climate change; they are caused because of an unsustainable fuel load and failed environmental practices.” ,"1 – Abatzoglou et al. (2016) Impact of anthropogenic climate change on wildfire across western US forests. PNAS. 2 – IPCC (2014) Climate Change 2014: Summary: for Policymakers. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. 3 – National Academies of Sciences, Engineering, and Medicine (2016) Attribution of extreme weather events in the context of climate change. The National Academies Press. 4 – Diffenbaugh (2020). Verification of extreme event attribution: using out of-sample observations to assess changes in probabilities of unprecedented events. Science Advances. 5 – Swain et al. (2020) Attributing extreme events to climate change: A new frontier in a warming world. One Earth. 6 – Swain et al. (2018) Increasing precipitation volatility in twenty-first-century California. Nature Climate Change. 7 – Dong et al. (2019) Mechanisms for an amplified precipitation seasonal cycle in the U.S. west coast under global warming. Journal of Climate. 8 – Westerling. (2016) Increasing western US forest wildfire activity: sensitivity to changes in the timing of spring. Philosophical Transactions of the Royal Society B. 9 – Jolly et al. (2015) Climate-induced variations in global wildfire danger from 1979 to 2013. Nature Communications. 10 – Goss et al. (2020) Climate change is increasing the risk of extreme autumn wildfire conditions across California. Environmental Research Letters. NOTES This fact check is available at IFCN’s 2020 US Elections FactChat #Chatbot on WhatsApp. Clickhere, for more.","Review: The claim that the forest fires currently burning in the western United States are caused by poor forest management and not climate change appeared in multiple Facebook posts published in September 2020. While forest management practices, specifically fire suppression, have increased the fuel load, scientific evidence also links climate change to hotter and drier conditions, which increase the amount of dry vegetative fuel and the total area burned in the western US[1]. Forest management efforts like thinning and prescribed burns are important to restore forests to the lighter fuel loads that existed before the fire suppression policies of the 20th century, says Valerie Trouet, an associate professor at the University of Arizona. But climate change is also a key contributor to fire severity today. As described in Abatzoglou and Williams (2016), “human-caused climate change caused over half of the documented increases in fuel aridity since the 1970s and doubled the cumulative forest fire area since 1984” (see figure below)[1]. Figure—Western US forest fire area on a logarithmic scale compared to standardised fuel aridity, with data points during the 1984-1999 (blue dots) and 2000-2017 (red dots) periods highlighted. Map insert shows the western US forest areas. From Abatzoglou et al. (2016)[1]. Several states in the western US, including California, Oregon, and Washington, are currently experiencing extreme drought (see figure below). August was also the hottest month on record for California. These conditions, combined with strong winds, increased the severity of the current wildfires. In addition to climate and weather, factors such as past fire suppression (causing fuel accumulation over time) and people living in closer proximity to wildlands also influence wildfire behavior, as described by the reviewers below. For a more in-depth discussion of how climate change influences wildfires in California, see our 2018 post: A discussion with experts on California wildfire links to climate change. UPDATE (8 October 2020): Stossel TV claimed this review was inappropriately used to apply a “Missing Context” flag to their video on Facebook. This claim is based on a misrepresentation of our process, and of the assessments of the scientists who contributed to this review. For an explanation of how we rated their video, read our post published here. Scientists’ Feedback: Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: [Comment from a previous evaluation of a similar claim] The claims that climate plays no role in natural disasters and wildfires fly in the face of a large peer-reviewed scientific literature showing clear links between climate change and extreme heat events, drought, and extreme rainfall as well as links between hotter and drier conditions and wildfire areas burned in many regions of the world[2-5]. All three factors – buildup of vegetation due to fire suppression, more people living in the wildland-urban interface, and hotter and drier conditions have contributed to severe wildfires in regions like the western US in recent years. A 2016 study showed that climate change is responsible for over half the increase in fuel aridity (drier fuel load), and has doubled the cumulative forest area burned[1]. Rising average global temperatures have led to higher spring and summer temperatures, which in turn have led to earlier spring snowmelt. Further, there is evidence that climate change is causing winter rains to come later in autumn, and stop earlier in spring[6,7]. This is extending the area and time periods in which forests become combustible, and in parts of California, fire season is now 50 days longer than in 1979[8,9]. Stefan Doerr Professor, Swansea University: [Comment from a previous evaluation of a similar claim] Several global climate trends promote fire: increased temperature, frequency, intensity and/or extent of heatwaves, droughts and extreme winds. This is very well established and summarised in the IPCC (2014) report[2,3].Climate change has led to an increase in area burned in regions where fires burn more intensely and have a greater impact (e.g. western USA and Canada)[1,10]. Daniel Swain Climate Scientist, University of California, Los Angeles: [Comment from a previous evaluation of a similar claim] This is misleading and incorrect as stated. While the legacy of 20th century forest management policies, as well as urban incursion into the wildlands, are indeed relevant in some areas, research has shown that such non-climate factors cannot account for the enormous increase in area burned by wildfire both in the broader American West and California specifically. In fact, drying of vegetation due to climate change is responsible for about half of the observed increase in western U.S. forest fire area burned over the past several decades[1]. More specifically in California, observed warming and drying more than doubled the occurrence of extreme fire weather conditions between 1979 and 2018—a trend that is attributable to human-caused climate change[10]."
https://science.feedback.org/review/western-us-wildfires-are-not-the-result-of-widespread-arson/,Inaccurate,"We The Governed, Glen Morgan, 2020-09-10","a distressing number of the [West coast] fires are not accidents, and willful arson is the cause.",,"Factually Inaccurate: Rumors that the widespread wildfires burning in California, Oregon, and Washington were started by arsonists are unfounded and contradicted by documentation of other causes of ignition.","Recent wildfires on the West Coast have been ignited by a number of sources, including lightning, power lines, and even a smoke machine at a party. Their severity is the result of strong winds and intense drought driven by a dry summer and record warmth, which is part of an ongoing human-caused warming trend.","it appears that a distressing number of these fires are not accidents, and willful arson is the cause.",,"Rumors like this one have spread widely, accusing extremists and protestors of starting the fires that are currently burning across California, Oregon, and Washington. Some of these rumors cite isolated incidents like the arrest of a Washington man at a fire in the median of a divided highway, which was quickly contained. However, multiple authorities responding to fires have stated that reports of widespread arson are false rumors. In Oregon, the Portland office of the FBI posted a statement asking the public to “help us stop the spread of misinformation”. Reports that extremists are setting wildfires in Oregon are untrue. Help us stop the spread of misinformation by only sharing information from trusted, official sources. Reports that extremists are setting wildfires in Oregon are untrue. Help us stop the spread of misinformation by only sharing information from trusted, official sources. pic.twitter.com/ENc4c3kjep — FBI Portland (@FBIPortland) September 11, 2020 — FBI Portland (@FBIPortland) September 11, 2020 The Douglas County Sheriff’s Office similarly posted to its Facebook page: “Rumors spread just like wildfire and now our 9-1-1 dispatchers and professional staff are being overrun with requests for information and inquiries on an untrue rumor that 6 Antifa members have been arrested for setting fires in Douglas County, Oregon. This is not true! Unfortunately, people are spreading this rumor and it is causing problems.” The Jackson County Sheriff’s Office posted: “We are inundated with questions about things that are fake stories. One example is a story circulating that varies about what group is involved as to setting fires and arrests being made. This is not true! When official information about the investigation is available it will be on reputable government, fire and law enforcement internet sites and social media pages.” The Oregonian has reported that an arson investigation is underway for the Almeda fire in Oregon, but quotes the Ashland police chief as saying, “One thing I can say is that the rumor it was set by Antifa is 100% false information. We have some leads, and none of it points in that direction.” At a 15 September news conference, Clackamas County Sheriff Craig Roberts said,“I want the public to completely understand that our office has no intelligence or information about any group committing any crimes. No arrests have been made associated with any group.” Asked about rumors of people planting gas cans or cutting down power poles that had been confirmed to be false, Sheriff Roberts said, “Let me give you an example of how things get spun out of control: We had some good Samaritans that actually saw a gas can in a suspicious place that just happened to be left behind. Just on their own, they said, ‘You know what, I’m going to take this and put it in a place so nobody has access to it.’ They hid it, next thing you know, somebody saw them doing that, the thing became suspicious, I called in our terrorism task force folks, they tracked it down, and they’re actually good Samaritans that are delivering water to the fire folks to help, and they were trying to do just a good deed.” Another set of claims focuses on a 14 September arrest in Portland of a man suspected of using Molotov cocktails to start several brush fires along the freeway. All of these fires were quickly extinguished, and are unrelated to wildfires in the state. According to the Portland Police Bureau: “East Precinct officers were dispatched with Portland Fire and Rescue to a report of multiple fires burning along the west side of the I-205 freeway. Portland Fire and Rescue extinguished three of them while passing community members put out the other three. All were caught early. No one was injured and no structures were burnt.” Oregon’s Riverside Fire is currently listed on InciWeb as human-caused, but Portland’s KOIN news reported that the Clackamas County Sheriff stated, “There’s a lot of concern that different organized groups might be involved in setting these fires. I can tell you that we have no evidence of that and that’s why we want to make perfectly clear that we’re looking at each and every tip that comes in. At this point, we have nothing to substantiate that there’s any group that is out there setting fires.” Human ignitions include accidents related to abandoned campfires or sparks from vehicles or other machinery. The Whitney Fire in Oregon was started by a downed powerline. Causes of other major fires in Oregon and Washington have not been determined. In California, meanwhile, the largest fires started during dry lightning storms in mid-August. California’s Dolan Fire, which has burned over 120,000 acres, is an exception. The Monterey County Sheriff’s Office arrested a man near the location of that fire’s origin and he has been charged with arson on forest land, battery, and cultivating marijuana, although the cause of the fire has not yet been officially determined. While steps to prevent ignitions are important when wildfire risk is high, it’s the dry conditions that make fires possible and determine their potential intensity, with subsequent weather conditions (such as winds) also playing an important role in wildfire behavior. Just as attempted arson would be unsuccessful in a wet forest, any type of ignition can lead to a large wildfire when fuels are extremely dry. Wildfire outbreaks don’t typically correlate with a specific ignition type (excepting lightning storms) but rather with weather conditions amidst drought. Much of Northern California, Oregon, and Washington are currently in severe to extreme drought after a dry and warm summer. August, for example, was the warmest on record for California and the tenth warmest for Oregon. August in both states was among the 30 driest on record. Combined with recent unfavorable winds, these conditions are responsible for the severity of the current fires. Across the American West, fuel aridity—the measure of how dry vegetation is on the landscape—has been increasing over time due to warming temperatures.[1] To learn more about the relationship between climate change and fire behavior in California, specifically, read our 2018 post on this topic: A discussion with experts on California wildfire links to climate change. Additionally, some rumors have used US-only maps to argue that fires suspiciously stop at the US-Canada border or at the US-Mexico border. This is false, and satellite data show (see below) that there are several fires in southern British Columbia, as well. Additional information on active fires can be found on British Columbia’s wildfire dashboard. A much smaller area of Canada is currently experiencing drought conditions, limiting fire risk. 1- Abatzaglou and Williams (2016) Impact of anthropogenic climate change on wildfire across western US forests, PNAS UPDATES: 16 September 2020: This post was updated with additional details. 18 September 2020: This post was updated with additional details. NOTES This fact check is available at IFCN’s 2020 US Elections FactChat #Chatbot on WhatsApp. Clickhere, for more."
https://science.feedback.org/review/planting-trees-can-help-mitigate-some-aspects-of-climate-change-but-it-cannot-solve-all-environmental-crises/,Lacks context,"8 Billion Trees, Pamela Anderson, 2020-08-23",“Trees provide a solution to almost all environmental crises we're facing. Trees reverse climate change by cleaning carbon from the air.”,,"Lack of context: Trees can absorb and store carbon, thus mitigating some effects of climate change, but tree planting alone cannot solve climate change because the amount of CO2 absorbed by forests is far less than the amount humans emit. As a result, tree planting needs to be complemented with other more effective solutions such as reducing fossil fuel emissions and avoiding deforestation.  Misrepresents a complex reality: The effects of tree plantings as a climate solution vary depending on tree species, tree age, geographic location, and how efforts are implemented. "," Trees provide a variety of ecosystem services, such as absorbing and storing carbon, that can help mitigate environmental crises and climate change. However, that alone is not sufficient to halt climate change. Reducing fossil fuel emissions and avoiding deforestation are necessary climate solutions, to which planting trees could provide additional benefits.",“Trees provide a solution to almost all environmental crises we're facing. Trees reverse climate change by cleaning carbon from the air.”,"1 – Lewis et al. (2019) Comment on “The global tree restoration potential.” Science. 2 – Griscom et al. (2017) Natural climate solutions. PNAS. 3 – Griscom et al. (2020) National mitigation potential from natural climate solutions in the tropics. Phil. Trans. R. Soc. B. 4 – Holl et al. (2020) Tree planting is not a simple solution. Science. 5 – Korner (2017) A matter of tree longevity. Science. 6 – Friedlingstein et al. (2019) Global carbon budget 2019. Earth System Science Data. 7 – Nabuurs et al. (2013) First signs of carbon sink saturation in European forest biomass. Nature Climate Change. 8 – Fuss et al. (2018) Negative emissions—Part 2: Costs, potentials and side-effects. Environmental Research Letters. 9 – Chazdon et al. (2019) Restoring forests as a means to many ends. Science.","Review: Initiatives to plant trees as a climate solution have sprouted up around the world over the past few years. One of these initiatives, 8 Billion Trees, recently published a video on Facebook featuring Pamela Anderson claiming that “trees provide a solution to almost all environmental crises we’re facing.” While planting trees can help mitigate some ongoing environmental crises, reducing fossil fuel emissions and avoiding deforestation are the most important climate solutions, as described by the reviewers below[1-4]. For example, an assessment of natural climate solutions strategies in Latin America, Africa, and Asia found that protecting forests, peatlands, and mangroves provided twice the climate mitigation potential as reforestation efforts (see figure below). From Griscom et al. (2020)[3]. The video also claims that “trees reverse climate change by cleaning carbon from the air.” Trees remove carbon from the air as they grow and can store carbon for long periods of time, however they only absorb a fraction of the carbon emitted by humans each year[5], and as such, it is incorrect to say that this approach can “reverse” climate change. “Global fossil fuel emissions totaled about 9.5 Gt C per year from 2009-2018, while Earth’s land ecosystems (i.e., forests, grasslands) sequestered about 3.2 Gt C per year from the atmosphere[6],” said Logan Berner, Assistant Research Professor at Northern Arizona University. “Thus, burning fossil fuels emitted about three times as much carbon each year as was taken up by all of Earth’s land ecosystems!” In addition, the amount of carbon sequestered by forests saturates over time and varies depending on tree species, tree age, and geographic location, as well as numerous other factors[2,4,7,8]. Although trees provide a variety of ecosystem services by stabilizing soil, preventing flooding, and creating and connecting habitat for a broad range of species[2,4], they can only mitigate some effects of climate change, not “reverse” or address “all environmental crises”, as claimed in the video. Tree plantings can also fail to deliver their intended climate benefits if efforts are not effectively designed, implemented, or monitored properly over time, as the reviewers describe below. Scientists’ Feedback: Erle Ellis Professor, University of Maryland, Baltimore County: [Comment from a previous evaluation of a similar claim] Tree growth can only slow down carbon accumulation in the atmosphere, not stop it. Ultimately, the only solution to climate change is to stop burning fossil fuels, which in turn requires a transition to inexpensive clean energy. Karen Holl Professor, University of California, Santa Cruz: [Comment from a previous evaluation of a similar claim] As Dr. Brancalion and I discuss in our brief article and a subsequent article that is currently in review, increasing tree cover is part of the solution to climate change but it is just one piece of the puzzle[4]. The most important steps are first reducing greenhouse gas emissions and second protecting existing forests and other high carbon storage ecosystems (e.g. wetlands). A few key points here: First, planting trees is not going to solve the problem of climate change if we don’t reduce greenhouse gas emissions. As temperatures rise and precipitation patterns change, large areas are becoming unsuitable habitat for trees due to direct water stress and indirectly through fires and insect outbreaks. Moreover, some existing forests are slowing in their capacity to uptake carbon[7]. Second, it is important to protect existing forests first. Existing forests, rain forests in particular, store large amounts of carbon both above- and below-ground. As a restoration ecologist who has spent over 25 years studying how to restore forests, I know that it is nearly impossible to restore exactly what was there before, and it makes much more ecological and economic sense to protect existing forests so that should be the priority. Yet, large scale forest clearing continues worldwide. For example, in the U.S. the Trump administration is proposing to allow logging in the Tongass National Forest, at the same time that they have expressed support for the Trillion Trees Act. Temperate rain forests store huge amounts of carbon. Likewise, in Brazil there are extensive efforts to restore the Atlantic forest ecosystem in southeastern Brazil at the same time that deforestation and forest fires have increased substantially in the past couple of years. Efforts should focus on reducing the drivers of deforestation and enforcing existing legislation that protects forest. Third, it is important to distinguish between tree planting and increasing tree cover or forest cover. Many forests are able to recover on their own if degrading factors are removed, so often it is not necessary to plant trees[9]. Allowing for natural recovery should be the first option for restoring forests, as it is more ecologically and economically sound. If it is necessary to plant trees either due to slow recovery or for socioeconomic reasons then the focus should be on restoring tree cover over the long-term. Many of these large-scale planting schemes focus on the number of trees put in the ground without considering who is going to care for and monitor the trees and whether the social conditions are in place for the trees to not be cleared. This has led to many massive tree planting failures. It also means that the cost of planting trees is substantially underestimated. The cost needs to include not only growing the seedling, digging the hole and planting the tree, but management such as clearing competitive vegetation and monitoring the outcomes of tree planting over the longer term. [Comment from a previous evaluation of a similar claim] The carbon sequestered in existing forests is far, far larger than planted trees, which further emphasizes that stopping deforestation should probably be a much higher priority than planting new forests. In addition, it will take decades for planted trees to store substantial amounts of carbon, which means that tree planting solutions are not a fast climate solution. By contrast, any effort that reduces fossil fuel or deforestation emissions are immediate climate solutions that benefit the atmosphere today and in the future. READ MORE Climate Feedback published an insight article exploring the potentials and limitations of tree planting as a climate solution."
https://science.feedback.org/review/article-by-cnn-exaggerates-studys-implications-for-future-greenland-ice-loss/,-1,"CNN, by Brandon Miller, Max Claypool, on 2020-08-14.",,"""Greenland's ice sheet has melted to a point of no return, according to new study""",,,,1 – King et al. (2020) Dynamic ice loss from the Greenland Ice Sheet driven by sustained glacier retreat. Communications Earth & Environment.2 – Aschwanden et al. (2019) Contribution of the Greenland Ice Sheet to sea level over the next millennium. Science Advances. 3 – Pattyn et al. (2018) The Greenland and Antarctic ice sheets under 1.5 °C global warming. Nature Climate Change. 4 – Horton et al. (2020) Estimating global mean sea-level rise and its uncertainties by 2100 and 2300 from an expert survey. npj Climate and Atmospheric Science.,"Reviewers’ Overall Feedback: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Stefan Rahmstorf Professor, Potsdam University: While most of this article is correct, I have to give it a low credibility rating because the attention-grabbing headline conclusion is not supported by the study the article is about: “Greenland’s ice sheet has melted to a point of no return, and efforts to slow global warming will not stop it from disintegrating.” What the paper actually finds is well described in its press release: “Even if humans were somehow miraculously able to stop climate change in its tracks […] the ice sheet would continue to shrink for some time.”[1] The key phrase here is “for some time”. Based on the study, I conclude that the time scale meant here is decades, maybe a century. However, complete loss of the ice sheet would take about a millennium even with unmitigated warming, and the process which decides over the complete ice loss is surface melt—not the ice discharge by glaciers flowing into the ocean at the margins of the ice sheet, which the study is about. When the ice sheet shrinks, it will withdraw further and further from the coast and ice discharge into the ocean will become less important. This is shown by model simulations that continue all the way until complete ice loss. The study reported on here is an observational study looking at ice flow changes in the past decades, not a model projection for future ice loss. It does not provide evidence about the eventual fate of the Greenland ice sheet. The impression given by many media articles, namely that the Greenland ice sheet is already doomed to be lost completely, is not supported by the evidence in the paper. While the concern about Greenland ice loss is certainly very serious and justified, the conclusion that it is already doomed is an over-interpretation of the results of this study. Twila Moon Research Scientist, University of Colorado, Boulder: The article correctly notes most measurements and facts and figures. However, it fails to provide nuance in critical areas regarding how quickly ice may be lost, whether this is a new scientific insight, and the role of human climate action in determining the future of Greenland ice loss (and associated sea level rise). Luke Trusel Assistant Professor, Pennsylvania State University: Greenland ice sheet melt and its discharge of ice into the ocean has increased over the last few decades, making it one of the largest contributors to global sea level rise. This is important and concerning, and there’s a clear human fingerprint on Greenland ice sheet mass trends. The referenced study by King and coauthors represents important new observations of Greenland’s mass loss and the large increases that have recently occurred[1]. However, the CNN article’s suggestion that Greenland has passed a tipping point is not well established. For example, a paper published in Nature Climate Change in 2018 by Pattyn and coauthors found that the tipping point (that is, the point where potentially irreversible change is set in motion) would be in the neighborhood of 1.5 to 2°C warming above pre-industrial[3]. We’re close, but not quite there yet. In my opinion, the most important point that is missing in the article is that our emissions trajectories *right now and in the next few decades* are critical for determining the rates and magnitudes of mass loss and sea level contributions from the Greenland ice sheet. Lower emissions mean a lower likelihood of reaching a tipping point, as well as lower amounts of warming in the atmosphere and ocean. Less warming means lower rates of mass loss from the Greenland ice sheet and enables greater opportunity for humans to respond to changing sea levels[3]. Annotations: The statements quoted below are from the article; comments are from the reviewers (and are lightly edited for clarity). melted to a point of no return, and efforts to slow global warming will not stop it from disintegrating Stefan Rahmstorf Professor, Potsdam University: While the Greenland ice sheet is certain to shrink further even without further warming, it is not at all clear whether it has crossed the point where it will be lost completely. The new study by King et al. has not examined this issue and does not say anything about it[1]. Neither does their press release, which states: “Even if humans were somehow miraculously able to stop climate change in its tracks […] the ice sheet would continue to shrink for some time.” It does not say “until it’s gone.” Twila Moon Research Scientist, University of Colorado, Boulder: It is correct that there is no longer a reasonable scenario in which the Greenland Ice Sheet is fully stabilized or gains significant ice. However, this statement ignores the very important matter of how quickly ice is lost. An excellent recent study by Aschwanden et al. demonstrates what a dramatic difference there is in ice loss under a low emissions scenario v. a high emissions scenario[2]. The critical matter right now (which has already been understood by glaciologists for some time) is not whether or not we lose ice from Greenland but how quickly ice is lost. dumps more than 280 billion metric tons of melting ice into the ocean each year Twila Moon Research Scientist, University of Colorado, Boulder: Yes, this is accurate. The Greenland Ice Sheet began consistently losing ice year-after-year around the turn of the 21st century and this number is close to the recent average for annual ice loss. greatest single contributor to global sea level rise Twila Moon Research Scientist, University of Colorado, Boulder: Scientists may quibble over this. Glaciologists usually divide Earth’s ice into 3 categories: Greenland Ice Sheet, Antarctic Ice Sheet, all other glaciers/ice caps. The amount of ice lost annually from Greenland is now very similar to that lost each year from the “all other glaciers/ice caps” category. it has caused a measurable change in the gravitational field over Greenland Twila Moon Research Scientist, University of Colorado, Boulder: Measuring changes in gravity is one important method used to determine how much ice is lost (or gained). There actually does not need to be a large change in ice mass for it to create a measurable change in the gravitational field. So it is a bit misleading to suggest that “measurable change in the gravitational field” is synonymous with “massive” ice loss. It is not. But it IS true that Greenland has lost a lot of ice in recent years. In fact, 2012 and 2019 both set records for ice loss within the historical record. Sea levels are projected to rise by more than 3 feet by the end of the century Stefan Rahmstorf Professor, Potsdam University: This is only true under a very high global warming scenario (about 4 °C global warming by 2100). For a mitigation scenario in line with the Paris agreement, experts expect a likely range of 30-65 cm rise by 2100 (relative to 1986–2005). See Horton et al. 2020[4]. Coastal states like Florida, and low-lying island nations are particularly vulnerable. Just 3 feet of sea level rise could put large areas of coastline underwater Stefan Rahmstorf Professor, Potsdam University: This is a completely valid concern. Rising seas already cause major problems and this will get ever worse during the course of this century. The question of whether the Greenland Ice Sheet is doomed to disappear completely in the end or eventually stabilizes at a smaller size concerns the very long term; it has no bearing on what happens in this century. Twila Moon Research Scientist, University of Colorado, Boulder: It’s useful to note that sea levels will not rise the same everywhere. Some coastal locations will experience much more or less sea level rise than the global average. For example, the U.S. Gulf Coast will experience more sea level rise than the global average. the ice sheet is retreating in rapid bursts, leading to a sudden and unpredictable rise in sea levels, making it difficult to prepare for the effects Twila Moon Research Scientist, University of Colorado, Boulder: I do not agree with this statement. Ice sheet edge retreat is not a direct measure of ice mass loss. Even if ice edge retreat happens in bursts, we cannot determine from that measure how much total ice will be lost each year. Also, sea level rise is the result of a combination of changes that include land ice melt, ocean heat causing ocean volume to increase, and local vertical land motion. I would argue that the current spread in future projections of sea level rise is not highly influenced by Greenland glacier retreat rates. Entire coasts of ice are retreating at once due to climate change Twila Moon Research Scientist, University of Colorado, Boulder: Correct. There is widespread retreat of the ice edge around all of the Greenland Ice Sheet. This is well documented."
https://science.feedback.org/review/the-long-term-survival-of-polar-bears-is-threatened-by-loss-of-sea-ice-due-to-global-warming-new-study-confirms-henry-fountain/,Correct,"The New York Times, Henry Fountain, 2020-07-20","""Global warming is driving polar bears toward extinction""",,Correct: Sea-ice loss due to global warming is threatening polar bear survival and reproduction according to numerous studies and recently confirmed in a new scientific article forecasting sea ice extent for different CO2 emissions scenarios.,"Sea-ice loss due to global warming is the most important threat to long-term survival and reproduction of polar bears. Under a high greenhouse gas emissions scenario, all but a few polar bear subpopulations are at risk of extinction by 2100. In the moderate greenhouse gas emissions scenario, some polar bear subpopulations could persist through the century.","""Global warming is driving polar bears toward extinction. Polar bears could become nearly extinct by the end of the century as a result of shrinking sea ice in the Arctic if global warming continues unabated.""",1 – Molnar et al. (2020) Fasting season length sets temporal limits for global polar bear persistence. Nature Climate Change. 2 – Stirling et al (2018) Effects of climate warming on polar bears: a review of the evidence. Global Change Biology. 3 – Stern et al (2016) Sea-ice indicators of polar bear habitat. The Cryosphere. 4 – Bromaghin et al (2015) Polar bear population dynamics in the southern Beaufort Sea during a period of sea ice decline. Ecological Applications. 5 – Lunn et al (2016) Demography of an apex predator at the edge of its range: impacts of changing sea ice on polar bears in Hudson Bay. Ecological Applications. 6 – Regehr et al (2010) Effects of earlier sea ice breakup on survival and population size of polar bears in Western Hudson Bay. The Journal of Wildlife Management. 7 – Obbard et al (2016) Trends in body condition in polar bears (Ursus maritimus) from the Southern Hudson Bay subpopulation in relation to changes in sea ice. Arctic Science. 8 – Hamilton et al (2014) Projected polar bear sea ice habitat in the Canadian Arctic Archipelago. PLoS One. 9 – Castro de la Guardia et al (2013) Future sea ice conditions in western Hudson Bay and consequences for polar bears in the 21st century. Global Change Biology. 10 – Regehr et al (2016) Conservation status of polar bears (Ursus maritimus) in relation to projected sea-ice declines. Biology Letters. 11 – Stirling et al (1999) Long-term trends in the population ecology of polar bears in western Hudson Bay in relation to climatic change. Arctic. 12 – Pilfold et al (2016) Mass loss rates of fasting polar bears. Physiological and Biochemical Zoology. 13 – Durner et al (2017). Increased Arctic sea ice drift alters adult female polar bear movements and energetics. Global Change Biology. 14 – Smith et al (1975) The breeding habitat of the ringed seal (Phoca hispida). The birth lair and associated structures. Canadian Journal of Zoology. 15 – Stirling et al (2004) Implications of warm temperatures and an unusual rain event for the survival of ringed seals on the coast of Southeastern Baffin Island. Arctic. 16 – Stirling (2002) Polar bears and seals in the Eastern Beaufort Sea and Amundsen Gulf: a synthesis of population trends and ecological relationships over three decades. Arctic. 17 – Kingsley (1979) Fitting the von Bertalanffy growth equation to polar bear age–weight data. Canadian Journal of Zoology. 18 – Theimann et al (2008) Polar bear diets and arctic marine food webs: insights from fatty acid analysis. Ecological Monographs. 19 – Laidre et al (2018) Historical and potential future importance of large whales as food for polar bears. Frontiers in Ecology and the Environment.,"Review: The claim has appeared in multiple media outlets, including The New York Times, The Guardian, BBC, Forbes, and Time, and has been shared on Facebook more than 18,000 times in total, according to Crowd Tangle. The claim is based on a study published July 2020 that projected range-wide declines in polar bear subpopulations under moderate and high greenhouse gas emissions scenarios due to losses of sea-ice habitat[1]. The article in The New York Times accurately describes results from this study. Sea-ice loss is currently the most important threat to the long-term survival of polar bears[2,3]. Polar bears rely on sea ice to feed on seals (their primary prey), mate, establish dens, and move throughout their range[2,3]. During the summer, sea-ice melt forces polar bears ashore where they often fast for months at a time due to inadequate food supplies[1]. While polar bears have energy reserves that facilitate their survival and ability to recruit cubs (i.e., lactation) during these fasts, body reserves are also limited[1]. Loss of sea-ice habitat has already led to lower survival, reproduction, and body condition in some polar bear subpopulations, including the southern Beaufort Sea, Western Hudson Bay, and Southern Hudson Bay populations[4-7]. To estimate how and when sea-ice loss will impact survival and reproduction in 13 polar bear subpopulations, Molnár et al. (2020) calculated how long polar bears could fast before adult survival and cub recruitment rapidly declined. Although data about how sea-ice loss affects population demographics is limited for most subpopulations, Molnár et al. used data from a subpopulation (Western Hudson Bay) as a baseline because it already experienced extended periods of fasting as a result of sea-ice declines (see figure below). Figure—Annual extent of sea ice in the Western Hudson Bay polar bear subpopulation derived from PMW data. Gray lines represent the daily extent of sea ice each year from 1979 – 2016 measured by satellite observations. Colored curves represent the means of the daily extent, with each color capturing a different time period: 1979-1988 (blue), 1989-1999 (green), 2000-2009 (yellow), and 2010-2016 (red). The study authors then calculated the energy needs of fasting polar bears for 13 subpopulations based on this baseline, while using sensitivity analyses to account for uncertainties and differences among subpopulations[1]. Molnár et al. then estimated losses of sea ice under moderate and high greenhouse gas emissions scenarios (RCP4.5 and RCP8.5, respectively) to project when declines in adult female and male survival and cub recruitment passed critical thresholds. As described in the study, “with high greenhouse gas emissions, steeply declining reproduction and survival will jeopardize the persistence of all but a few high-Arctic subpopulations by 2100. Moderate emissions mitigation prolongs persistence but is unlikely to prevent some subpopulation extirpations within this century,” (see figure below)[1]. Figure—Timelines of risk for when cub recruitment and adult survival of male and female polar bears will begin declining in 13 subpopulations across the species range. Subpopulations are listed along the y-axis and colored by ecoregion. Effects on adult female survival (orange), adult male survival (blue), and cub recruitment (magenta) are shown for each subpopulation under moderate (a) and high (b) greenhouse gas emissions scenarios. As the reviewers explain below, The New York Times article accurately describes results from this study. In addition, this study is consistent with previous scientific studies predicting declines in polar bear subpopulations with continued loss of sea ice due to global warming[8-13]. Scientists’ Feedback: The article is accurate and summarizes our findings very well. I only have one extremely minor comment, which doesn’t affect the overall accuracy of this article. In the second paragraph, the author writes that “the loss of sea ice would force the animals onto land and away from their food supplies for longer periods”. In some cases (e.g. the Beaufort Sea populations), the animals may choose not to go on land but instead follow the ice as it retreats over the Arctic Basin. As these are deep, dark, unproductive waters, the effect is therefore the same as going on land (food-deprivation), and this omission does not affect the overall accuracy of the article. I read the NYT article and thought it represented the findings well. Andrew Derocher Professor, University of Alberta: The statement of “nearly extinct” is consistent with the findings of Hamilton et al. (2014) which stated “Under business-as-usual climate projections, polar bears may face starvation and reproductive failure across the entire Archipelago by the year 2100.”[8] Further, the study concluded with “Nevertheless, by 2100 all regions of the study area may cross the critical point-of-no-return, putting the persistence of the CAA [Canadian Arctic Archipelago] polar bear populations in jeopardy.” This study examined the Canadian Arctic Archipelago populations where sea ice is expected to persist the longest. Castro de la Guardia et al. (2013) examined sea ice in Hudson Bay and that study stated “Our predictions suggest that the habitat of polar bears in WH [Western Hudson Bay] will deteriorate in the 21st century. Ice predictions in A1B [medium greenhouse gas emissions] and A2 [high greenhouse gas emissions] suggest that the polar bear population may struggle to persist after ca. 2050. Predictions under B1 [low greenhouse gas emissions] suggest that reducing GHG emissions could allow polar bears to persist in WH throughout the 21st century.”[9] Thus, the Molnár et al. study is supported by both Hamilton et al. (2014) and Castro de la Guardia et al. (2013)[1,8,9]. The time frame and approach in these two studies is similar to that of Molnár et al. and use a fasting duration limit relative to sea ice loss estimation. Regehr et al. (2016) stated “The estimated probabilities that reductions in the mean global population size of polar bears will be greater than 30%, 50% and 80% over three generations (35–41 years) were 0.71 (range 0.20–0.95), 0.07 (range 0–0.35) and less than 0.01 (range 0 – 0.02), respectively.”[10] Given that Molnár et al. consider a much longer timeframe and that it considers a severe climate change scenario (RCP 8.5) as the upper bound, the study is consistent with Regehr et al. (2016). They also examined a lower climate change scenario (RCP 4.5), which shows impacts on polar bears that would be consistent with projected changes noted by Regehr et al. (2016).[1,10] The statements about extended fasting, shorter feeding period, and traveling more, are consistent with the broader literature addressed in the review by Stirling and Derocher (2012) and both empirical and projection studies by Stirling et al. (1999), Lunn et al. (2016), Pilfold et al. (2016), and Durner et al. (2017)[11,5,12,13]. In summary, I find that the statement is consistent with the published work being addressed and that the statement overall is consistent with the broader peer-reviewed literature on polar bears. Ian Stirling Adjunct Professor, University of Alberta: Overall, I would say Molnar et al. 2020 should be regarded as scientifically correct, quantitative in terms of the data analyzed, and analytically supported[1]. I started and maintained the long-term monitoring of the polar bear population in Western Hudson Bay (WH). My early results were clear enough by the late 1990s for the analyses to be the first to confirm the negative effects of climate warming on polar bears. WH is the longest continuous data base on the effects of climate warming on polar bear abundance, survival, and reproduction anywhere in the Arctic. When I initially started the long-term monitoring of polar bears there it was because I wanted to learn more about the amount of natural variation inherent in the polar marine ecosystem because of its obvious importance to conservation practises. I had already seen the results of large scale interannual changes in the ecosystem on polar bears and ringed seals in the Arctic (Beaufort Sea) and on Weddell seals in the Antarctic and those experiences were enough to convince me that understanding more about natural fluctuations in the ecosystem was something we really needed to know a lot more about. It was only by the mid-1990s (the period identified by Molnar) that we began to realize from our data that something else was going on besides possible natural cycles and, because we had a long-term database, and the ability to continue the monitoring, that we were able to identify and confirm what was happening because of climate warming. I think it is fair to say that the physiological parameters with respect to reproduction and body condition, etc. measured in WH could be reasonably applied to polar bears elsewhere. What such focused models projecting into the future do not take into account overall though of course is that the whole arctic marine ecosystem (and the interrelationships of all species) is changing because of climate warming and the speed of such changes will likely accelerate as time progresses so exactly what might happen specifically to polar bears as an icon species becomes more difficult to predict precisely the farther out we get. That said, the modelling approach remains invaluable for what it clearly indicates is coming our way soon, regardless. I think a major strength of the Molnar paper is that it correctly assesses the populations (for which there are sufficient data) independently rather than as a single world population[1]. That appears to be the major weakness in the Hamilton et al. (2014) paper, which comes to the same conclusion as Molnar (see their Conclusion: s/Significance statement) but is based mainly only on bears in the Canadian Arctic Archipelago and treats the subpopulations resident there as a single population and not as several independent populations[8]. Still, the fact that these two papers basically come to a more or less identical conclusion, via different routes and levels of analysis is interesting. While I think the Molnar paper is quite correct overall, I think it overlooks two important ecological situations which don’t weaken their overall conclusions but could have given them a bit more ecological depth of understanding of some important qualifications for some populations and might have been important to include, though the space restrictions in journals like Nature might preclude doing so. In my opinion, a common flaw in almost all (if not all) the big overview papers that predict bears having problems loss of ice because of climate warming and then becoming extinct, or nearly so, by some date is that they tend to make a 1:1 relationship between the area of ice and its decline and the subsequent decline in the bears for nutritional reasons. However, ecologically, the relationship is much more complicated and geographically variable than a simple 1:1 relationship. Ringed seals, which are the major food source of polar bears throughout their range are reliant on having hard wind blown snow over the breathing holes of the adult females in their prime breeding habitat for giving birth to their young[14]. With the warmer weather and rain that will appear in most areas, probably at significantly increased levels well before 2100, the devastating decline in ringed seal reproduction and survival will have an immediate negative effect on the bears’ nutrition, survival, and reproduction[15]. We already know that reproductive failure of ringed seals (as seen on decadal scale intervals in the southern Beaufort Sea[16]) causes immediate and very strong negative effects on reproduction and survival of young polar bears as well as lowering the body condition in adults[17]. If such levels of loss of ringed seal pups is significant because of climate for several years in some populations, the negative effects on the bears there will be significant. Also, there are major differences in the availability of different prey species for polar bears in different populations[18]. In particular, the role of some of these prey species to provide carrion in some populations that could help a smaller number of bears survive for a protracted period has been overlooked. For example, the potential for walrus populations (which will be less negatively impacted by climate warming in some areas) to provide a long-term potential food source, at predictable locations, for both predation and scavenging in several areas. Similarly, where whale carcasses resulting from natural mortality occur in predictable locations, they may provide a long-term food source for bears in areas such as Chukotka[19]."
https://science.feedback.org/review/greenhouse-gases-cause-global-warming-by-trapping-infra-red-radiations-not-by-causing-more-holes-in-the-ozone-layer/,Incorrect,"Instagram, Otis Holland, 2020-07-11",Greenhouse gases emitted into the ocean are causing more holes in the ozone layer … “the ozone layer has holes in it causing global temperature to rise”,,"Incorrect: Global warming is caused by anthropogenic emissions of greenhouse gases, particularly CO2, which trap infra-red radiation and cause the atmosphere to retain heat, not by greenhouse gases creating holes in the ozone.Factually inaccurate: Chlorofluorocarbons, halons, and other ozone-depleting substances cause holes in the stratospheric ozone layer, not the greenhouse gas CO2, which was referred to in the post by stating it is emitted into the ocean. Ozone-depleting substances were limited in 1987, preventing the formation of more and deeper holes in the ozone.","It is a common misconception that Global Warming would be due to holes in the ozone layer caused by Greenhouse gases (GHG). Instead, GHGs warm the Earth’s surface by trapping infra-red radiations, limiting the natural process by which the Earth’s surface cools. Holes in the stratospheric ozone layer are caused by anthropogenic emissions of chlorofluorocarbons (CFC), halons, and other ozone-depleting substances. Reductions in ozone-depleting substances due to the Montreal Protocol have prevented the formation of more and deeper ozone holes.",“the green house gasses that have been emitted into the ocean over that last 150 years would still be releasing slowly and causing more and more holes in the ozone layer as time goes on … the ozone layer has holes in it causing global temperature to rise. It would be so easy to plant a small tree of keep plants in you house or in your garden. This could create more oxygen and build up the ozone layer. ”,"1 – IPCC (2014) Climate Change 2014: Summary for Policymakers. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. 2 – World Meteorological Organization (2018) Executive Summary: Scientific Assessment of Ozone Depletion: 2018. Global Ozone Research and Monitoring Project–Report No. 58. 3 – World Meteorological Organization (2018) Chapter 5: Stratospheric ozone changes and climate. Global Ozone Research and Monitoring Project–Report No. 58. 4 – Banerjee et al. (2020) A pause in Southern Hemisphere circulation trends due to the Montreal Protocol. Nature. 5 – Solomon et al. (2016) Emergence of healing in the Antarctic ozone layer. Science. 6 – Morgenstern et al. (2008) The world avoided by the Montreal Protocol. Geophysical Research Letters. 7 – Kroeger et al. (2014) Reforestation as a novel abatement and compliance measure for ground-level ozone. PNAS.","Review: The claim appeared in an Instagram post published by Otis Holland in July 2020. The post states that greenhouse gases that are emitted into the ocean, referring to CO2[1], cause holes in the ozone. Contrary to the claim, stratospheric ozone depletion is caused by anthropogenic emissions of chlorofluorocarbons (CFCs), halons, hydrochlorofluorocarbons, and other ozone-depleting substances[2]. These long-lived substances, which are found in aerosol spray cans, refrigerants, and industrial pollutants, break down ozone molecules causing holes in the ozone layer. While ozone can affect climate, the rise in global temperature is the result of human-caused emissions of CO2, methane, nitrous oxide, and other greenhouse gases that trap and re-emit infra-red radiation, not by causing holes in the ozone layer as claimed (see figure below)[1,3,4]. Figure—The estimated role of different factors influencing global surface temperatures from 1850 to 2017. Observed temperatures are shown in black dots. Global warming over the past 150 years was primarily driven by greenhouse gas emissions (red), not ozone (purple). From Carbon Brief. Contrary to the claim that holes in the ozone layer will become more prevalent over time, scientific studies have found that the Antarctic ozone is recovering[4,5]. According to the 2018 WMO/UNEP Scientific Assessment of Ozone Depletion, global and Antarctic ozone concentrations are projected to recover to 1960 levels by the end of the century, assuming future compliance with the Montreal Protocol, which limits the use of ozone-depleting substances (see figure below)[2]. Figure—Comparisons of total ozone observations (red points and lines) and chemistry climate models (black lines with grey regions showing uncertainty) for the globe (top) and Antarctic (bottom). Annual global total ozone is averaged over 60°N to 60°S latitudes, whereas Antarctic total ozone is averaged over 60°S to 80°S latitudes. Models project that ozone concentrations will return to levels observed in the 1960s by 2100, assuming future compliance with the Montreal Protocol. Black lines with arrows indicate the years that ozone abundances are projected to return to values observed in 1980. Adapted from World Meteorological Organization (WMO) Executive Summary: Scientific Assessment of Ozone Depletion (2018)[2]. In 1987, the United Nations passed an international treaty, the Montreal Protocol, to limit the use of CFCs and other ozone-depleting substances[6]. Models of the Arctic ozone demonstrate that the Montreal Protocol has prevented the formation of a deeper ozone hole, as well as additional holes (see figure below). Figure—Observed and modeled column ozone in the Arctic. Satellite observations from the Ozone Monitoring Instrument in March 2011 (a). Models of Arctic Ozone show projected changes in the ozone with (b) and without (c) the Montreal Protocol. From World Meteorological Organization (WMO) Executive Summary: Scientific Assessment of Ozone Depletion (2018)[2]. While planting trees in your house or garden to increase oxygen can potentially influence ground-level ozone, this approach will not alter stratospheric ozone on human life timescales[7]. Overall, the claim does not accurately describe the mechanism of global warming or the causes and trends of ozone depletion."
https://science.feedback.org/review/article-by-michael-shellenberger-mixes-accurate-and-inaccurate-claims-in-support-of-a-misleading-and-overly-simplistic-argumentation-about-climate-change/,-1,"Forbes, by Michael Shellenberger, on 2020-06-28.",,"""On Behalf Of Environmentalists, I Apologize For The Climate Scare""",,,,"1 – IPCC (2014) Climate Change 2014: Summary: for Policymakers. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. 2 – National Academies of Sciences, Engineering, and Medicine (2016) Attribution of extreme weather events in the context of climate change. The National Academies Press. 3 – Diffenbaugh (2020). Verification of extreme event attribution: using out of-sample observations to assess changes in probabilities of unprecedented events. Science Advances. 4 – Swain et al. (2020) Attributing extreme events to climate change: A new frontier in a warming world. One Earth. 5 – Ceballos et al. (2015) Accelerated modern human–induced species losses: Entering the sixth mass extinction. Science Advances. 6 – Dirzo et al. (2014) Defaunation in the Anthropocene. Science. 7 – Young et al. (2016) Patterns, causes, and consequences of Anthropocene defaunation. Annual Review of Ecology, Evolution, and Systematics. 8 – Ceballos et al. (2017) Biological annihilation via the ongoing sixth mass extinction signaled by vertebrate population losses and declines. PNAS. 9 – Stona et al. (2018) Co-extinctions annihilate planetary life during extreme environmental change. Scientific Reports. 10 – IPBES (2018) The IPBES assessment report on land degradation and restoration. 11 – Barnosky et al. (2011) Has the Earth’s sixth mass extinction already arrived? Nature. 12 – Urban (2015) Accelerating extinction risk from climate change. Science. 13 – Barnosky et al. (2012) Approaching a state shift in Earth’s biosphere. Nature. 14 – Wake and Vredenburg (2008) Are we in the midst of the sixth mass extinction? A view from the world of amphibians. PNAS. 15 – Andela et al. (2017) A human-driven decline in global burned area. Science 16 – Doerr et al. (2016) Global trends in wildfire and its impacts: Perceptions versus realities in a changing world Philosophical Transactions of the Royal Society B. 17 – Schoennagel et al. (2017) Adapt to more wildfire in western North American forests as climate changes. PNAS. 18 – Abatzoglou et al. (2016) Impact of anthropogenic climate change on wildfire across western US forests. PNAS. 19 – Goss et al. (2020) Climate change is increasing the risk of extreme autumn wildfire conditions across California. Environmental Research Letters. 20 – U.S. Global Change Research Program (2018) Impacts, risks, adaptation in the United States: Fourth National Climate Assessment, Volume II. 21 – Behrenfeld et al. (2006) Climate-driven trends in contemporary ocean productivity. Nature. 22 – Dangendorf et al. (2019) Persistent acceleration in global sea-level rise since the 1960s. Nature Climate Change. 23 – Lyra et al. (2016) Sensitivity of the Amazon biome to high resolution climate change projections. Acta Amazonica. 24 – Wang et al. (preprint, in review) ESD Reviews: mechanisms, evidence, and impacts of climate tipping elements. Earth System Dynamics. 25 – Yang et al. (2014) Spatial and temporal patterns of global burned area in response to anthropogenic and environmental factors: Reconstructing global fire history for the 20th and early 21st centuries. Journal of Geophysical Research: Biogeosciences. 26 – Swain et al. (2018) Increasing precipitation volatility in twenty-first-century California. Nature Climate Change. 27 – Dong et al. (2019) Mechanisms for an amplified precipitation seasonal cycle in the U.S. west coast under global warming. Journal of Climate. 28 – Westerling. (2016) Increasing western US forest wildfire activity: sensitivity to changes in the timing of spring. Philosophical Transactions of the Royal Society B. 29 – Jolly et al. (2015) Climate-induced variations in global wildfire danger from 1979 to 2013. Nature Communications. 30 – Le Quere et al. (2019) Drivers of declining CO2 emissions in 18 developed economies. Nature Climate Change. UPDATES: 9 July 2020: This post has been updated with additional references clarifying the discussion on the sixth mass extinction within the scientific community. 10 July 2020: This post has been updated to include a comment from Kerry Emanuel.","Reviewers’ Overall Feedback: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: Shellenberger’s article promoting his new book “Apocalypse Never” includes a mix of accurate, misleading, and patently false statements. While it is useful to push back against claims that climate change will lead to the end of the world or human extinction, to do so by inaccurately downplaying real climate risks is deeply problematic and counterproductive. Shellenberger’s claims that climate plays no role in natural disasters and wildfires fly in the face of a large peer-reviewed scientific literature showing clear links between climate change and extreme heat events, drought, and extreme rainfall as well as links between hotter and drier conditions and wildfire areas burned in many regions of the world[1-4]. Shellenberger also falls into the trap of seeing a single technology (nuclear) as the one true solution to climate change, and mistakenly sees denigrating other clean energy technologies as the best way to promote it. The real world involves messy trade-offs and uncertainties, and decarbonization will involve a range of different technological solutions across industries and geographies rather than a single panacea. For more details on each, see my comments below. Stefan Doerr Professor, Swansea University: The article argues that society has been misled about causes and consequences of climate change, which has led to “climate alarmism.” The author advocates that we should be less concerned about climate change than many environmentalists argue. Whilst the latter is relative depending on how concerned an individual is and which specific (and perhaps extreme) view this aligns with, some of the supporting statements in the article related to wildfire are (i) inaccurate for key facts supporting argumentation, or (ii) omit important information that leads to flaws in the conclusions. “Climate change is not making natural disasters worse”. This is incorrect for wildfires. Several global climate trends promote fire: increased temperature, frequency, intensity and/or extent of heatwaves, droughts and extreme winds. This is very well established and summarised in the IPCC (2014) report[1,2]. “Fires have declined 25% around the world since 2003″. It is correct that the total global area burned has OVERALL declined over the last decades, BUT this is incorrectly used to argue that climate change is not affecting wildfires. The overall decrease is largely due a substantial reduction in flammable vegetation in African grasslands arising from human land use changes. Climate change has led to an increase in area burned in regions where fires burn more intensely and have a greater impact (e.g. western USA and Canada)[18,19]. This is omitted, leading to a false perception. “The build-up of wood fuel and more houses near forests, not climate change, explain why there are more, and more dangerous, fires in Australia and California”. Partially correct[17], but the assertion that the climate change related factors outlined above do not also contribute to increasingly “dangerous fires” is fundamentally flawed. It is comparable to suggesting that smoking alone and not obesity is responsible for an increased risk of cardiovascular disease. Both factors are clearly important. Daniel Swain Climate Scientist, University of California, Los Angeles: The article presents a mix of out-of-context facts and outright falsehoods to reach conclusions that are, collectively, fundamentally misleading. The author claims to reference specific sources, including “the IPCC, the Food and Agriculture Organization of the United Nations (FAO), [and] the International Union for the Conservation of Nature (IUCN).” However, the author’s claims are broadly unsupported by any of these authoritative bodies[1]. Gerardo Ceballos Professor, Universidad Nacional Autonoma de Mexico: This is not a scientific paper. It is intended, I guess, to be an article for the general public. Unfortunately, it is neither. It does not have a logical structure that allows the reader to understand what he would like to address, aside from a very general and misleading idea that environmentalists and climate scientists have been alarmist in relation to climate change. He lists a series of eclectic environmental problems like the Sixth Mass Extinction, green energy, and climate disruption. And without any data nor any proof, he discredits the idea that those are human-caused, severe environmental problems. He just mentions loose ideas about why he is right and the rest of the scientists, environmentalists, and general public are wrong. Being objective, this is a really bad article. It will cause confusion among the public—perhaps that is his idea. He indicates, with no data, that we are not in the Sixth Mass Extinction. I will explain here why he is wrong. For a long time, we have been aware that our activities have caused the extinction of many species. The case of the dodo, the first human-caused extinction in modern times (1600 AD) is relatively well-known for the general public[5]. In the last decade, there has been a plethora of scientific studies that have carefully analyzed the current extinction rates and have compared them with the natural or background rates occurring in the last million years[6-8]. Evolution of life proceeds as a dynamic balance of the extinction and speciation processes. While some species become extinct others are generated by speciation events. Under normal times, when Earth is not suffering a global catastrophe, the normal extinction rate is called the “background extinction rate.” However, in the last 600 million years life has experienced 5 mass extinctions, where most species on Earth have disappeared. These mass extinctions were each caused by a natural catastrophe, such as a meteorite, or happened over thousands or hundreds of thousands of years, causing the extinction of 70 to 90% of all living species. In 2015, I showed with my colleagues from the National Autonomous University of Mexico and Stanford University that we have entered the Sixth Mass Extinction (see figure below)[5]. Figure—Cumulative vertebrate species that have gone extinct or extinct in the wild according to IUCN data from 2012. Dashed black line represents the background extinction rate. From Ceballos et al. (2015)[5]. The 543 species of vertebrates (mammals, birds, reptiles, amphibians, and fishes) that were lost over the last 120 years would have become extinct in 10,000 years under the background extinction rates prevailing in the last million years. In other words, in the last century we lost in one year the same number of species that would have been lost in 100 years! We and other scientific groups have also shown that the extinction crisis is more severe because hundreds of millions of populations of animals and plants have disappeared in the last 40 years[5-9]. Those extinctions are accelerating, threatening the ecosystems that support life on Earth. If the current extinction crisis continues unchecked, we will lose entire ecosystems and the critical services they provide, including the proper combination of the gases of the atmosphere that make life on Earth possible, provision of fresh water, pollination and pest and disease control[8]. Jennifer Francis Senior Scientist, Woods Hole Research Center: Many statements are half-truths or based on cherry-picked information. Some are outright false. For example, it’s ludicrous to state “climate change is not making natural disasters worse.” An abundant and rapidly growing body of peer-reviewed scientific research identifies numerous ways that climate change is increasing the likelihood and intensity of various extreme weather events, exacerbating coastal flooding, and destroying ecological systems[1,2,6,18,19]. “Humans are not causing a ‘sixth mass extinction’” An exceptionally rapid loss of species is occurring and expected to continue. Climate change is not the only factor responsible—pollution, habitat deterioration, over fishing and hunting, and invasive species are also contributing. Human fingerprints are all over these factors[5-14]. “Climate change is not making natural disasters worse” This statement is refuted by numerous peer-reviewed scientific studies[1-4]. While disasters related to non-climate-change events (such as volcanoes, earthquakes, tsunamis) have not increased in frequency, those associated with climate change have tripled in frequency since the 1980s (see figure below). Figure—The number of geophysical, meteorological, hydrological, and climatological natural events that occurred globally from 1980-2017. From NatCatSERVICE. “Fires have declined 25% around the world since 2003” This is true in terms of a global average, mainly because forests have been cut down and replaced with agricultural land and because of fire suppression activities[15]. Some areas, however, are experiencing more frequent, larger, and more damaging fires—such as the U.S. western states, Alaska, northern Canada, and northern Eurasia[18,19]. This statement is misleading at best. “Carbon emissions are declining in most rich nations and have been declining in Britain, Germany, and France since the mid-1970s” This is true, but it’s in large part because high-emission industries have been moved to developing countries. Global carbon emissions are still increasing steadily (see figure below). “The build-up of wood fuel and more houses near forests, not climate change, explain why there are more, and more dangerous, fires in Australia and California” Both factors are contributing to increased fires[16]. Ryan Sriver Associate Professor, University of Illinois: First off, it is largely an opinion piece and many of the claims are unverifiable or written in a way that is misleading, such as: “Fires have declined 25% around the world since 2003”. What exactly does this mean, the number of fires, duration, area burned, etc.? Another such misleading claim is “Climate change is not making natural disasters worse”. Again, what natural disasters is the author referring to with this blanket statement, and what time frame, the last 5 years, 20 years, 100 years? The claim is vague and misleading in particular for climate and weather extremes. Temperature and precipitation extremes are getting worse with global warming leading to more severe and widespread heatwaves and drought[1-4]. This is well documented in the community assessments and observations, such as the 4th National Climate Assessment[20]. In addition, oceans are getting warmer and the atmosphere is wetter, which—combined with global sea-level rise—is making the flooding and precipitation damages from tropical cyclones and hurricanes more severe[1,2,21,22]. Finally, there is essentially no mention of arguably the biggest risk of climate change: sea-level rise! The only statement I see is the claim: “Adapting to life below sea level made the Netherlands rich not poor.” This statement acknowledges that sea-level rise is indeed happening and that adaptation will make nations better off economically. Statements such as these are dangerous and misleading. Sea-level rise poses a major threat to coastal communities with global socio-economic implications, and we are already seeing the negative impacts in more frequent and severe flood events in the US. These damages will only worsen as the polar ice sheets continue to melt, with potentially catastrophic effects on coastal cities and ecosystems, real estate markets, insurance industries, human migration, and national security. Kerry Emanuel Professor of Atmospheric Science, MIT: In his article, Michael Shellenberger claims that “climate change is not making natural disasters worse”. This begs the question of what exactly is meant by “natural disasters”, but no matter how one defines them, this statement is patently false. Let us assume that Shellenberger is defining natural disasters as deaths from events that could conceivably have a climate connection, such as floods, droughts, and hurricanes. In the period between 1900 and 2020, global deaths from these disasters have declined steeply. There is little question about why this has happened, and it is the immensely gratifying effects of greatly improved warnings, evacuations, and resilience. For example, in Bangladesh, where a single storm killed as many as 500,000 people in 1970, the government and non-governmental organizations have built many emergency evacuations shelters that have saved arguably millions of people in subsequent cyclones that have been meteorologically as bad or worse. If there is a climate change signal, it would appear as a lessening of this happy trend toward decreased fatalities, but it would be very difficult if not impossible to extract such a signal. We do not know from this data whether climate change is decreasing the rate of decline of deaths from natural disasters or not. If, on the other hand, we look at economic damage, normalized by world domestic product, the signal is equally clear but in the other direction….damages from weather-related natural disasters have been increasing greatly. One could plausibly argue that this is because of a global migration toward risky coastal regions, and so it is not unequivocal that this increase is owing to climate change. The cleanest way to look at climate effects on natural phenomena is to look at the phenomena themselves. Here there is strong and mounting evidence that climate change is increasing precipitation extremes (floods and droughts), conditions for wildfires, and the incidence of strong hurricanes[1,2]. Whichever way one looks at it, Shellenberger’s statement is not defensible. Annotations: The statements quoted below are from the article; comments are from the reviewers (and are lightly edited for clarity). as an energy expert…invited by the Intergovernmental Panel on Climate Change (IPCC) to serve as Expert Reviewer of its next Assessment Report Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: This credential sounds much more impressive than it actually is. Anyone who wants to can sign up as an expert reviewer for the IPCC. The Amazon is not “the lungs of the world” Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: While this phrase was inaccurately spread in some news stories earlier this year, climate scientists – and the majority of activists – have never claimed this to be the case. There is, however, a real danger that a combination of logging and climate change could transition much of the Amazon to a savannah-like ecosystem this century[23,24]. Climate change is not making natural disasters worse Daniel Swain Climate Scientist, University of California, Los Angeles: On the whole, this claim is incorrect. While there are clearly certain types of natural disasters unaffected by climate change (earthquakes and volcanic activity, for example), and certain kinds of disasters for which there is an absence of evidence regarding a detectable influence from climate change (tornadoes, for example), there is a long and growing list of extreme event/disasters types regarding which the scientific literature strongly supports links to climate change. These include, but are not limited to: extreme heatwave intensity and frequency, drought intensity, wildfire extent and severity, and the flood hazards associated with tropical cyclones/hurricanes (both from oceanic storm surge and freshwater flooding associated with heavy precipitation). Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: This is patently false. While there are some types of natural disasters with no (volcanoes, earthquakes) or very limited (tornadoes) climate links, others such as extreme heat events, droughts, and extreme rainfall have clear attribution to climate changes. The US National Academy of Science published a report in 2016 on the role of climate change in extreme events that is quite helpful in understanding where linkages are – and are not – well understood[2]. This figure from the report shows our understanding and attribution of climate change impacts on extreme events, by event type. Fires have declined 25% around the world since 2003 Daniel Swain Climate Scientist, University of California, Los Angeles: I cannot speak to this specific statistic, but I emphasize that it is largely irrelevant in context and certainly misleading, since it conflates both climate and non-climate related factors. There are strong links between climate change and wildfire extent and severity in many regions globally. It’s less clear whether there are links between climate change and wildfire frequency, but that’s not really the relevant metric here. Instead, climate change is clearly modulating the characteristics of wildfire in many regions—broadly increasing the dryness and flammability of vegetation, and allowing fires to become more intense and to burn more extensive areas. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: This statement is accurate but misleading. The vast majority of fires globally are purposefully set for agricultural clearing, and these have declined in recent years. Conflating all fires with forest and wildfires – as Shellenberger does – is not helpful in understanding changing drivers of fire risk. A 2014 study in the Journal of Geophysical Research by Dr. Jia Yang at Auburn University and colleagues suggests that in the tropics climate change may have also reduced the area burned over the past 50 years, due, in part, to wetter conditions[25]. However, they find that climate change has likely increased fire risk in the high latitudes and mid-latitudes over recent decades. Figure—Contribution of different factors in changes since 1900 in forest-fire area globally and for different regions. Effects of climate change (including changes in temperatures and precipitation) are shown by the vertical stripes. Human land management activity is shown by the diagonal stripes, while the effect of CO2 fertilization and nitrogen deposition is shown by the dots. From Yang et al. (2014)[25]. Hotter and dryer conditions have been a major factor in the increase in areas burned by wildfires in many regions – such as the western US – in recent years. The amount of land we use for meat — humankind’s biggest use of land — has declined by an area nearly as large as AlaskaZeke Hausfather Director of Climate and Energy, The Breakthrough Institute: This statement is accurate (according to FAO data) and represents an important decoupling of land use and livestock production in spite of increasing global meat consumption – though some of the reduction is offset by increased land use for agricultural crops for animal feed. That said, there are large climate impacts of meat consumption apart from land use, and growing meat consumption is still driving deforestation in areas like the Amazon even as overall pasture use shrinks. So while peak pasture is certainly a positive thing, it does not translate into notable reductions in emissions to-date, as emissions from land use changes have remained largely unchanged. It does not – as Shellenberger seems to suggest – in any way indicate that climate change is a less serious problem than commonly thought, just that it’s possible to mitigate our impacts by changing practices and technologies. The build-up of wood fuel and more houses near forests, not climate change, explain why there are more, and more dangerous, fires in Australia and California Daniel Swain Climate Scientist, University of California, Los Angeles: This is misleading and incorrect as stated. While the legacy of 20th century forest management policies, as well as urban incursion into the wildlands, are indeed relevant in some areas, research has shown that such non-climate factors cannot account for the enormous increase in area burned by wildfire both in the broader American West and California specifically. In fact, drying of vegetation due to climate change is responsible for about half of the observed increase in western U.S. forest fire area burned over the past several decades[18]. More specifically in California, observed warming and drying more than doubled the occurrence of extreme fire weather conditions between 1979 and 2018—a trend that is attributable to human-caused climate change[19]. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: Here Shellenberger sets up a false dichotomy. All three factors – buildup of vegetation due to fire suppression, more people living in the wildland-urban interface, and hotter and dryer conditions have contributed to severe wildfires in regions like the western US in recent years. For example, there is a strong year-to-year relationship between fuel aridity – driven by hotter and dryer conditions – and area burned in the western US. Figure—Western US forest fire area on a logarithmic scale compared to standardised fuel aridity, with datapoints during the 1984-1999 (blue dots) and 2000-2017 (red dots) periods highlighted. Map insert shows the western US forest areas. From Abatzoglou et al. (2016)[13]. A 2016 study showed that climate change is responsible for over half the increase in fuel aridity (drier fuel load), and has doubled the cumulative forest area burned[18]. Rising average global temperatures have led to higher spring and summer temperatures, which in turn have led to earlier spring snowmelt. Further, there is evidence that climate change is causing winter rains to come later in autumn, and stop earlier in spring[26,27]. This is extending the area and time periods in which forests become combustible, and in parts of California, fire season is now 50 days longer than in 1979[28,29]. From 4th National Climate Assessment, based on data from Abatzoglou et al. (2016)[13,15]. Carbon emissions are declining in most rich nations and have been declining in Britain, Germany, and France since the mid-1970sZeke Hausfather Director of Climate and Energy, The Breakthrough Institute: This claim substantially overstates the long-term success that rich countries have had in decarbonizing their economies. Rich nations as a whole (using OECD nations as the grouping of rich countries) emit 25% more CO2 today than they did in the mid 1970s. While a number of countries (Germany, France, UK) do emit less today than in the 1970s, their experience is not generalizable to rich countries as a whole. These calculations also do not include emissions associated with increased consumption of goods produced in places like China, which matters quite a bitin recent decades. Figure—Countries’ consumption (orange line) and production (blue) emissions as a percent of their 1990 emissions. The grey area represents the difference between the two. Based on data from the Global Carbon Project. Chart by Carbon Brief. OECD emissions as a whole have declined around 10% since 2007, with 18 (of 37) OECD countries experiencing sustained reductions in emissions. This is encouraging progress, and shows that absolute decoupling (growing economy with falling emissions) is possible – even taking changes in consumption-based emissions into account. Figure—Changes in CO2 emissions from fossil fuel combustion for 18 countries with declining emissions during 2005-2015. From Le Quere et al. (2019)[30]. Wood fuel is far worse for people and wildlife than fossil fuels Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: Shellenberger is correct here that burning wood in cookstoves in the developing world is terrible for the climate, human health, and nature. Replacing it with fossil fuels – or even better, grid-connected electricity – is an important step in reducing indoor air pollution and black carbon emissions. To the extent that modern biomass is used to replace fossil fuels for electricity generation, it is quite controversial and opposed by most environmental advocates. It also represents only a small fraction of the clean energy added globally each year – the vast majority of which is from solar, wind, and nuclear. Preventing future pandemics requires more not less “industrial” agriculture Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: There is broad agreement in the epidemiological and virological studies of zoonoses that the most important factor in the development of new zoonotic diseases is land-use change. The development of wild lands, whether caused by agricultural extensification, mining, or other factors, simultaneously shrinks the habitat of wildlife and brings that wildlife in close proximity to human settlements. To the extent that agricultural intensification reduces pressure on wildlands, it can help reduce risk of future pandemics. However interesting, this argument has little to do with climate impacts. As a result, half of the people surveyed around the world last year said they thought climate change would make humanity extinct. And in January, one out of five British children told pollsters they were having nightmares about climate change.Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: Climate change will not cause the end of the world, and scientists can do more to push back against misleading popular narratives about human extinction. At the same time, minimizing the impacts of climate change through misleading or cherry-picked examples – as Shellenberger does at times in this article – is not a particularly effective response. 100% renewables would require increasing the land used for energy from today’s 0.5% to 50%Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: While renewable sources use more land (and there are other reasons why 100% renewables – vs. a more expansive 100% clean energy – is not necessarily the best policy goal, this substantially overstates the required land. Accounting for land use from generation, resource production (e.g. mining), and resource transport, studies find that solar requires 3.6x more land, wind 5.8x more land, and hydro 26x more land than fossil fuels. This increase in required land area is important – particularly for countries like Japan where land availability is limited – but is far lower than the 100x land increase Shellenberger inaccurately claims. Greenpeace didn’t save the whales, switching from whale oil to petroleum and palm oil didZeke Hausfather Director of Climate and Energy, The Breakthrough Institute: Neither restrictions nor substitutes were the primary factor in the decline in industrial whaling during the 20th century. Scarcity was. Modern whaling vessels and technology hunted most whale populations into near-extinction and as that occurred, whaling fleets and catch declined. Whales have come back because of restrictions (enacted after whaling declined substantially as populations dwindled) and the fact that we do now have substitutes for almost everything we hunted whales for."
https://science.feedback.org/review/study-evaluates-natural-and-human-causes-of-recent-rapid-warming-rate-at-the-south-pole/,Accurate,"The New York Times, Henry Fountain, 2020-06-29",Surface air temperatures at the bottom of the world have risen three times faster than the global average since the 1990s.,,"Accurate: Recorded temperatures at the South Pole weather station increased three times as much as the global average between 1989 and 2018. This is a statement about one station at the South Pole, specifically, and not broadly representative of global warming in Antarctica as a whole.","This statement accurately describes data analyzed in a recently published scientific study. As the article also explains, that study concluded that the temperature trend at this specific location was boosted by natural variability, and is not representative of the current human-caused climate change across Antarctica.","Surface air temperatures at the bottom of the world have risen three times faster than the global average since the 1990s[...] While the warming could be the result of natural climate change alone, the researchers said, it is likely that the effects of human-caused warming contributed to it.","1- Clem et al. (2020) Record warming at the South Pole during the past three decades, Nature Climate Change 2- Simpkins et al. (2014) Tropical Connections to Climatic Change in the Extratropical Southern Hemisphere: The Role of Atlantic SST Trends, Journal of Climate 3- van der Broeke and van Lipzig (2003) Factors Controlling the Near-Surface Wind Field in Antarctica, Monthly Weather Review: 4- Kowk and Comiso (2002) Spatial patterns of variability in Antarctic surface temperature: Connections to the Southern Hemisphere Annular Mode and the Southern Oscillation, Geophysical Research Letters 5- Marshall and Thompson (2016) The signatures of large‐scale patterns of atmospheric variability in Antarctic surface temperatures, JGR Atmospheres","This statement is based on recent study published by Clem et al. in Nature Climate Change[1]. (The study’s first author also described it in an article for The Conversation.) The study analyzed temperature data from the Amundsen-Scott South Pole Station, and then analyzes Southern Hemisphere weather patterns to evaluate the causes of the recent warming rate. Averaged over the 30-year period from 1989 to 2018, annual mean temperatures at the South Pole station have increased at a rate of about 0.61°C per decade. South Pole temperature data (top) and running 30-year trend calculation (bottom). Source: Clem et al./Nature Climate Change Over that same time period, global average surface temperatures have increased 0.6°C, equating to a rate of 0.2°C per decade. So it’s accurate to say that South Pole temperatures have increased at three times the global average. Calculated temperature change from 1989 to 2018.Source: NASA But it’s important to note that this is a statement about the South Pole, specifically, and not broadly representative of Antarctica as a whole. As illustrated in the figure below, other Antarctic stations recorded a slower rate of warming, while others have even cooled over this time period. Unlike the Arctic, which has seen a widespread and rapid rate of warming, the Antarctic experiences particularly variable weather patterns. These are driven by natural oscillations of regional ocean surface temperatures and atmospheric circulation[2,3,4,5]. Temperature change since 1989 for 20 Antarctic stations.Source: Clem et al./Nature Climate Change To understand why the South Pole station experienced such rapid warming in recent years, Clem et al.[1] analyzed wind patterns. They found that the last 30 years saw a higher frequency of winds from the warmer Weddell Sea rather than the colder interior of East Antarctica. In climate model simulations, they found that the observed trend is high compared to most simulated warming trends caused by human-caused greenhouse gas emissions. Clem et al.[1] concludes that the South Pole station warming trend likely requires a significant contribution from natural variability. Specifically, they find a correlation between sea surface temperature patterns in the tropical Pacific Ocean and the wind pattern that brings warmer air to the South Pole. They write, “While radiative forcing from greenhouse gas increases probably intensified the recent South Pole warming, the observed trend remains within the upper bounds of natural variability inferred from unforced, pre-industrial simulations and can be explained via a strong cyclonic anomaly in the Weddell Sea resulting from coupling of negative [Interdecadal Pacific Oscillation] and positive [Southern Annular Mode] during the twenty-first century.”"
https://science.feedback.org/review/climate-scientists-agree-that-human-caused-greenhouse-gas-emissions-are-primarily-responsible-for-climate-change-contrary-to-claims-in-clear-energy-alliance-video/,Incorrect,"Clear Energy Alliance, Mark Mathis, 2020-06-10","The scientific consensus on whether global warming is human caused is not 97 percent, it’s less than 1 percent. There is no way to measure the human impact on climate change.",,Factually inaccurate: Studies analyzing the peer-reviewed scientific literature show that the vast majority of climate scientists (and research) conclude that anthropogenic factors are primarily responsible for climate change.  Misunderstanding of science: The claim that human impacts on climate change cannot be measured or separated from natural causes contrasts with many lines of evidence demonstrating that human influences far outweigh natural effects.,The vast majority of climate scientists agree that anthropogenic factors are primarily responsible for climate change. Numerous scientific studies and summary reports demonstrate that natural and human influences on the climate can be studied and quantified.,"The scientific consensus on whether global warming is human caused is not 97 percent, it’s less than 1 percent. There is no way to separate natural climate cycles from man made influences such as the burning of fossil fuels. Consequently, there is no way to measure the human impact. If we are having an impact, the question is how much? The honest answer is we just don’t know.","1 – Anderegg et al. (2010) Expert credibility in climate change. PNAS. 2 – IPCC (2014) Climate Change 2014: Summary: for Policymakers. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. 3 – Doran et al. (2009) Examining the scientific consensus on climate change. Eos. 4 – Santer et al. (2013) Human and natural influences on the changing thermal structure of the atmosphere. PNAS. 5 – Feldman et a. (2015) Observational determination of surface radiative forcing by CO2 from 2000 to 2010. Nature. 6 – Cook et al. (2013) Quantifying the consensus on anthropogenic global warming in the scientific literature. Environmental Research Letters. 7 – Cook et al. (2016) Consensus on consensus: a synthesis of consensus estimates on human-caused global warming. Environmental Research Letters. 8 – Wuebbles et al. (2017) Executive summary. In: Climate Science Special Report: Fourth National Climate Assessment, Volume I 9 – IPCC, 2013: Summary for Policymakers. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change 10 – Powell (2015) Climate scientists virtually unanimous: anthropogenic global warming is true. Bulletin of Science, Technology and Society. 11 – Rosenberg et al. (2010) Climate change: a profile of US climate scientists’ perspectives. Climatic Change. 12 – Schmidt et al. (2014) Reconciling warming trends. Nature Geoscience. UPDATES: 26 June 2020: This post was updated to include a comment from William Anderegg.","Review: The claims appeared in a Facebook video published by Clear Energy Alliance in June 2020, and has received more than 90,000 views since it was published. The vast majority of climate scientists agree that human-caused greenhouse gas emissions are responsible for most of the change in global climate over the past century[1,2,3]. Climate scientists can also separate natural and man made influences on the climate and quantify anthropogenic impacts, contrary to claims made in the video[2,4,5]. In the video, Mark Mathis states that the scientific consensus that Earth’s recent warming is mostly man made is less than one percent, not 97 percent. This claim contradicts several scientific studies that have found 90 to 100 percent of scientists agree that anthropogenic factors are the main cause of recent climate change[1,3,6,7]. For example, a study by Anderegg and colleagues found that “97 – 98% of the climate researchers most actively publishing in the field surveyed here support the tenets of ACC [Anthropogenic Climate Change] outlined by the Intergovernmental Panel on Climate Change, and (ii) the relative climate expertise and scientific prominence of the researchers unconvinced of ACC are substantially below that of the convinced researchers.”[1] These results are consistent with findings from a study conducted by Cook et al. (2013), which was discussed in the video. The scientific consensus of climate experts on human contributions to climate change is not less than 1 percent as claimed. According to the IPCC, “It is extremely likely that more than half of the observed increase in global average surface temperature from 1951 to 2010 was caused by the anthropogenic increase in greenhouse gas concentrations and other anthropogenic forcings together.”[2] The 2017 US National Climate Assessment report states, “This assessment concludes, based on extensive evidence, that it is extremely likely that human activities, especially emissions of greenhouse gases, are the dominant cause of the observed warming since the mid-20th century. For the warming over the last century, there is no convincing alternative explanation supported by the extent of the observational evidence.”[8] Contrary to several claims made in the video, human influences on climate change can be separated from natural causes and measured, as the reviewers describe below[2,4,5]. For example, the IPCC demonstrates that anthropogenic drivers of global warming far outweigh the effects of solar forcing (see figure below)[9]. Figure—Radiative forcing estimates in 2011 relative to 1750. Values are global average radiative forcing, partitioned according to the emitted compounds or processes that result in a combination of drivers. Source IPCC AR5[9]. Finally, the video presents a figure comparing climate model predictions to balloon and satellite measurements. This figure, created by Dr. John Christy, suffers from a number of issues that ultimately mislead readers about differences between the balloon and satellite measurements and climate model predictions. It focuses on temperatures in the mid-troposphere, above the Earth’s surface, and plots the data in a highly misleading way, as described by the reviewers below. The measurements also stop at 2011, omitting the past 9 years of data. In addition, the figure does not show the distribution of error in the balloon and satellite measurements or the spread of model predictions, exaggerating discrepancies between the two. Scientists’ Feedback: William Anderegg Associate Professor, University of Utah: The video’s claims that the scientific consensus on whether climate change is human-caused is less than 1 percent is utterly false. The video completely misrepresents and misleads about one of the studies on scientific consensus, while completely ignoring that multiple independent studies done by different research teams across the world have separately arrived at consensus levels of 97% or greater. Our study arrived at a 97-98% estimate in 2010[1]. A separate study by Doran & Kendall-Zimmermann found very similar levels of consensus using entirely different methods[3]. Still another study estimated >99% consensus[10]. An entirely different study placed the consensus at over 94%[11]. Thus, there are multiple, independent studies that validate and confirm the Cook et al results[7]. The claims made in this video about the scientific consensus are blatantly false and completely at odds with the peer-reviewed literature. James Renwick Professor, Victoria University of Wellington:[Comment from a previous evaluation of a similar claim.] There are very reliable numerical estimates of the human contribution to warming, as detailed in the last IPCC report. The headline statement from IPCC AR5 was “It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century.” Gavin Schmidt Director, NASA Goddard Institute for Space Studies:[Comment from a previous evaluation of a similar claim.] There is indeed overwhelming evidence for warming in the last century. [The] claim that no one knows the attribution of this to human impacts is not a valid description of the state of knowledge. There are indeed plenty of studies that use statistical or model-based fingerprints to assess this and they overwhelmingly find a dominance of human activities over natural forcings or internal variability. For the more recent period (1950 onwards) the claims are even stronger—that effectively all the warming is caused by human activity with only a ~10% uncertainty due to internal variability. Patrick Brown Assistant Professor, San Jose State University:[Comment from a previous evaluation of a similar claim.] Careful analysis that attempts to take into account all major factors and their evolution in time indicates that anthropogenic increases in greenhouse gasses account for more than 100% of the observed warming on the century timescale (requiring cancellation from cooling influences). See the summary graphic from Carbon Brief, below. Figure—The estimated role of different factors influencing global surface temperatures from 1850 to 2017. Observed temperatures are shown in black dots. Global warming over the past 150 years was primarily driven by greenhouse gas emissions (red). From Carbon Brief. Comments on figure comparing models to balloon and satellite data Victor Venema Scientist, University of Bonn, Germany:[Comment from a previous evaluation of a similar claim.] John Christy has shown this plot for many years on his blog and in congressional hearings. If it were a robust result, it would be scientifically interesting, however in all these years Christy has not published a scientific article on his claims, and colleagues have had to reverse-engineer how it was made. One thing that is clear is that due the 5-year averages the strong warming in the last 3 years is strongly suppressed in this plot. Due to the averaging of the balloon datasets and the satellite datasets, the large uncertainty in the observations is no longer visible. It is not good practice to align measurements and models by selecting only one year that happened to have been warm; to reduce the influence of such an arbitrary choice scientists normally use a longer period to align different datasets. Several of these problems have been discussed at RealClimate, but unfortunately Christy has not updated his graph. Climate models inform us about long-term warming and have not been developed for short-term predictions, which are strongly influenced by fluctuations from, for example, El Niño. The timing of El Nino is not predictable more than a year in advance. This problem is even more the case for the upper air temperatures shown here by John Christy than for the surface temperature. The uncertainty of climate models results for short-term prediction is expected to be about twice the model spread of the CMIP models. Gavin Schmidt Director, NASA Goddard Institute for Space Studies:[Comment from a previous evaluation of a similar claim.] As I’ve discussed on RealClimate, Christy makes a number of minor and one major choice in his graph that all combine to exaggerate the discrepancy between models and observations of the mid-troposphere changes. The major issue is that he does not show the structural errors in the observations, nor does he compare to the spread in the model output. Better graphs that do not make those partial choices are available: This is not to say that there are no discrepancies—there are, just not as dramatic as Christy claims. The bulk of the trends in the models for this metric are above what is reported, but with any discrepancy, there are multiple potential causes which all need to be looked at[12]. 1) the observations may be wrong, 2) the models may be wrong, 3) the experiments may not have been realistic, or 4) the comparison is flawed. While #4 has historically been the case for many satellite-model comparisons in the past, it is no longer much of a problem. However, #1 remains a distinct possibility—and ongoing revisions to these datasets often give rise to systematic shifts in the trends. #2 is also possible—though assuming the only issue must relate to climate sensitivity is naive. But #3 is a known problem—the CMIP5 simulations did not have sufficient volcanoes, and did not predict the decrease in solar activity over the last decade or so[12]. Ignoring #1 and #3 in favor only of a claim about #2 is not good science. Note too that on other metrics the models are ok, or don’t shift as quickly as observed (sea ice, Hadley cell expansion, etc.)—only discussing issues where the bias is one specific way, is again a very partial approach."
https://science.feedback.org/review/article-in-the-guardian-misleads-readers-about-sensitivity-of-climate-models-by-narrowly-focusing-on-single-study-jonathan-watts/,-1,"The Guardian, by Jonathan Watts, on 2020-06-13.",,"""Climate worst-case scenarios may not go far enough, cloud data shows""",,,,1 – IPCC (2013) Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. 2 – Williams et al. (2020). Use of short‐range forecasts to evaluate fast physics processes relevant for climate sensitivity. Journal of Advances in Modeling Earth Systems. 3 – Palmer (2020). Short-term tests validate long-term estimates of climate change. Nature. 4 – Andrews (2020) Historical simulations with HadGEM3‐GC3.1 for CMIP6. Journal of Advances in Modeling Earth Systems. 5 – Tokarska et al. (2020). Past warming trend constrains future warming in CMIP6 models. Science Advances. 6 – Forster et al. (2020) Latest climate models confirm need for urgent mitigation. Nature Climate Change. 7 – Knutti et al. (2017) Beyond equilibrium climate sensitivity. Nature Geoscience. 8 – IPCC (2007) What explains the current spread in models’ Climate Sensitivity Estimates? UPDATES: 22 June 2020: This post was updated to include a comment by Mark Zelinka,"Reviewers’ Overall Feedback: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Richard Betts Professor, Met Office Hadley Centre & University of Exeter: Equilibrium climate sensitivity (ECS) is a very important topic of great interest, but also complex and still subject to considerable uncertainty and ongoing research. The article does recognise the uncertainty in the latest models and quotes a leading scientist in this regard, but the headline and first two sentences overstate the scientific confidence and give the impression of a more substantial update to scientific understanding than is actually the case. The caveat in the second sentence reads as if the high ECS in the new models is provisionally accepted and merely needs further checking, rather than being something that the modellers are not yet sure about either way. The article is not clear on the uncertainty in the previous estimates of ECS and gives the impression that there was previously a fairly precise estimate of “around 3°C”, but in fact that was already fairly uncertain, as explained by the IPCC[1]. The latest research would be more accurately characterised as still not yet ruling out high climate sensitivity that was previously thought possible but relatively unlikely, rather than suggesting that high climate sensitivity is now more likely than previously believed. Mark Richardson Research Associate, Colorado State University/NASA JPL: This article’s main theme is broadly accurate. Many new climate models, which better fit satellite cloud measurements, have a high value of “climate sensitivity.” It includes important doubts about how “such a high figure does not fit with historical records”. Technical errors like confusing the national origin of a model and the description of a provided percentage don’t affect these main conclusions. Readers should be aware that this article is slanted to the “shock” and “surprise” of these results and misses context from past work, such as the uncertainty ranges provided in past UN climate reports. However, the article is clear about these being mostly model results, reports how only around a quarter of these new models show very high sensitivity, and mentions the counterbalance of evidence from the historical record. Taken together I mark this article as “accurate”, with elements that are “exaggerating” and “imprecise/unclear”. Reto Knutti Professor, ETH Zürich: The main problem with this Guardian article is not incorrect statements, but that it is cherry picking one single result, misinterpreting it, surround it by strong quotes from people who have no expertise in that area, thereby painting a doomsday scenario (“modelling suggests climate is considerably more sensitive to carbon emissions than thought”) that is highly misleading and completely unsupported by the evidence. The oversimplification is in two steps, the first in a Nature comment on the original paper[3]. Here Tim Palmer is incorrect in saying that the results of the original paper “support the estimates [for climate sensitivity]”[2,3]. The fact that the new high climate sensitivity model does well on six hour forecasts does not imply a) that the model is fine in general, and does not imply b) that it is the only model that is capable of doing that. The relationship between short-term forecasts and climate feedbacks is not demonstrated, and the evidence from hundreds of other papers on the topic is ignored. On a) the agreement on short-term forecasts simply means that this model is doing this particular thing well. However, this particular model is one of the two worst in simulating the warming over the past 40 years. It shows basically no warming globally until 1980 or 1990, even cooling over land, and a massive surge after about 1990[4]. The details are likely complicated, but are probably related to too-strong feedbacks (high climate sensitivity), compensated by too strong aerosol cooling until 1990, a hypothesis put forward ages ago in energy balance models. Indeed the Guardian piece mentions that, but only briefly at the end. On b) as pointed out by others, nobody has demonstrated that the high sensitivity is related to short-term forecast skill in these newer models. Everything is different in the new model, so the improvement may have come from some other change. One would have to demonstrate that many versions of that model with low climatology are doing significantly worse on short-term forecasts, and would have to demonstrate that this is also true for models from other centers. The fact that one particular test cannot rule out a high climate sensitivity does not make it likely. It simply means that we do not know. But there are other lines of evidence that point to the canonical 2-4.5°C range. One is the recent warming since 1950 or so, the other is paleoclimate estimates, the third is process understanding and feedback estimates from cloud data and surface observations We and others have shown recently that almost all of the high climate sensitivity models in fact tend to overestimate recent warming[5], the Met Office model being one of the two worst, and taking that into account suggests that many of the new CMIP6 models are biased high, and that future warming is similar to what it was in earlier models. While it is correct that we are seeing models with high climate sensitivity, the evidence is growing that there are issues with at least some of these models. In summary, the Guardian article is cherry-picking a single technical paper and over-interpreting it as being relevant for the prediction of long term warming, without sufficient context on the vast amount of literature that does not support such a conclusion. Joeri Rogelj Professor, Centre for Environmental Policy at Imperial College London: The article correctly reports that the most recent versions of some climate models estimate more warming for a given increase in CO2 concentrations. It is also correct in highlighting that how clouds are represented in these models is the likely reason for these higher estimates. However, it does not report all the science available on this topic and its claims are thus misleading. The article suggests that the only information currently available from scientific studies is that things look much worse, and that otherwise more research is needed to understand whether this is really the case. However, available studies that have looked at what these new model projections mean have found that models with higher warming are worse in capturing global warming trends over the past decades, making their projections of very high warming less probable[4]. This is important context that was omitted from the article. Paulo Ceppi Senior Lecturer, Imperial College London: The article suggests that new modelling results have led scientists to revise their understanding of the role of clouds for climate change. This is misleading. Current scientific consensus is that clouds will amplify warming, but most evidence does not point towards an extreme amplifying effect. So while extreme high warming scenarios cannot be entirely ruled out, there is no convincing evidence that the amplifying effect of clouds is stronger than we previously thought. While the new Nature paper cited in the article is thought-provoking[2], its significance is overstated, and the paper should have been discussed in the context of other recent evidence that does not support the high-sensitivity modelling results. Piers Forster Professor, University of Leeds: In this article there is some science on the latest climate models and their cloud feedbacks that have been reported before. However, quotes by Rockstrom and the writer [Watts] are unsupported opinions that make misleading interpretations of the new science that warming will be worse than we thought. These claims are not supported by other lines of evidence showing our estimates of warming rates have been stable over time. Mark Zelinka Research Scientist, Lawrence Livermore National Laboratory: I would characterize the article as overstating the importance of a single result from a single model without sufficient context. A highly sensitive model might have a great-looking climatological state and perform really well on short-term weather forecasts, but even a broken clock is right twice a day. This is hyperbole of course: This is an excellent model and by no means “broken”, but it remains to be rigorously shown that this model is giving a more accurate picture of our future than what we previously thought. More generally, the consequences of continued greenhouse gas emissions are dire enough if climate sensitivity is in line with the existing scientific consensus; whether this new more sensitive model is more accurate is mostly immaterial to that fact. Annotations: The statements quoted below are from the article; comments are from the reviewers (and are lightly edited for clarity). “Worst-case global heating scenarios may need to be revised upwards in light of a better understanding of the role of clouds, scientists have said.” Richard Betts Professor, Met Office Hadley Centre & University of Exeter: This appears to be based on the view of a scientist who was not involved in developing the new models. A quote later in the article shows that a scientist with a leading role in the latest models is much more cautious and said it needs more research before conclusions can be drawn. Piers Forster Professor, University of Leeds: There is no consensus in the community what these would be. Different scientists have different views, so there is no standard worst-case scenario to revise, see our CCC blog. “Recent modelling data suggests the climate is considerably more sensitive to carbon emissions than previously believed” Richard Betts Professor, Met Office Hadley Centre & University of Exeter: This statement is not correct. Equilibrium Climate Sensitivity (ECS) has always been quite uncertain, and the high values in the new models are within the range previously thought possible, although relatively unlikely. A value of around 5°C in some of the CMIP6 models is outside the “likely range” of ECS assessed in the IPCC 5th Assessment Report (AR5), but it is still not in the AR5 “very unlikely” range of above 6°C[1]. The recent studies cited in this report conclude that the high ECS values cannot be ruled out by the methods used in those studies, but they do not conclude that high ECS is more likely than previously believed. Piers Forster Professor, University of Leeds: The latest models might also be over sensitive[6]. “25% of them show a sharp upward shift from 3C to 5C in climate sensitivity” Richard Betts Professor, Met Office Hadley Centre & University of Exeter: It’s not clear what this statement is based on, as no source is given. Although several CMIP6 models produce an ECS above the upper end of the range of the CMIP5 models, this range was 1.2°C – 4.7°C so it is not clear where the description of a shift from 3°C to 5°C comes from. Mark Richardson Research Associate, Colorado State University/NASA JPL: I don’t see where this statement comes from either. The top 25% of models out now have climate sensitivity of about 4.8°C or above, so one part of this statement gives a broadly accurate summary. But several of those are new versions of models that previously had climate sensitivity quite a bit higher than 3°C, so there wasn’t a “shift” of those models. “For 40 years, it has been around 3C” Richard Betts Professor, Met Office Hadley Centre & University of Exeter: Actually the estimates of Equilibrium Climate Sensitivity (ECS) have long been around 1.5°C – 4.5°C, with higher values still thought possible. The IPCC 5th Assessment Report judged that there was up to a 10% chance of ECS being greater than 6°C, and the likelihood of an ECS of 5°C was assessed as less than 33% but more than 10%[1]. Piers Forster Professor, University of Leeds: I completely agree with Richard Betts, and in fact the latest models agree very well with this range of ECS in general[6]. “He said climate sensitivity above 5C would reduce the scope for human action to reduce the worst impacts of global heating. “We would have no more space for a soft landing of 1.5C [above preindustrial levels]. The best we could aim for is 2C,” he said.” Mark Richardson Research Associate, Colorado State University/NASA JPL: This is a fair interpretation of the consequences: climate sensitivity of 5°C would make it almost impossible to achieve the stated temperature targets. But there is still plenty of evidence for climate sensitivity being in the historically likely 1.5 – 4.5°C range, so this should be kept in mind. “the EU’s Community Earth System Model” Mark Richardson Research Associate, Colorado State University/NASA JPL: The Community Earth System Model is from US institutions, but it’s accurate to say that it’s from “leading research bodies” and has a high climate sensitivity. “Previous IPCC reports tended to assume that clouds would have a neutral impact because the warming and cooling feedbacks would cancel each other out.” Mark Richardson Research Associate, Colorado State University/NASA JPL: “Assume” is ungenerous—this was based on calculations using physics and the available observations. For example, in 2007 they looked at how climate model clouds affected their climate sensitivity and talked about a “very large inter-model spread”, i.e., you could get net warming or cooling, and we didn’t have the information to rule out either[8]. Reto Knutti Professor, ETH Zürich: IPCC does not “assume”, they quantify based on observations and models. And while cloud feedbacks are uncertain, in 2013 the conclusion was already that the overall effect was likely positive (i.e., contributing to warming), specifically only 17% probability for it being negative (cooling).[1] IPCC AR5 WG1 page 592: “Based on the preceding synthesis of cloud behaviour, the net radia­tive feedback due to all cloud types is judged likely to be positive. This is reasoned probabilistically as follows. First, because evidence from observations and process models is mixed as to whether GCM cloud feedback is too strong or too weak overall, and because the positive feedback found in GCMs comes mostly from mechanisms now sup­ported by other lines of evidence, the central (most likely) estimate of the total cloud feedback is taken as the mean from GCMs (+0.6 W m–2 °C–1). Second, because there is no accepted basis to discredit individual GCMs a priori, the probability distribution of the true feedback cannot be any narrower than the distribution of GCM results. Third, since feed­back mechanisms are probably missing from GCMs and some CRMs suggest feedbacks outside the range in GCMs, the probable range of the feedback must be broader than its spread in GCMs. We estimate a probability distribution for this feedback by doubling the spread about the mean of all model values in Figure 7.10 (in effect assuming an additional uncertainty about 1.7 times as large as that encapsu­lated in the GCM range, added to it in quadrature). This yields a 90% (very likely) range of −0.2 to +2.0 W m–2 °C–1, with a 17% probability of a negative feedback.”[1] “But in the past year and a half, a body of evidence has been growing showing that the net effect will be warming. This is based on finer resolution computer models and advanced cloud microphysics.” Mark Richardson Research Associate, Colorado State University/NASA JPL: I think this is generally fair: the available satellite data in particular have shown that clouds seem to act in a way that coincides with higher climate sensitivity. The fusion of satellite data with climate models has been vital for this. “Scientists caution that this is a work in progress and that doubts remain because such a high figure does not fit with historical records.” Richard Betts Professor, Met Office Hadley Centre & University of Exeter: It’s correct to have included this, but the message here seems less confident than that conveyed by the headline and opening sentence. “Catherine Senior, head of understanding climate change at the Met Office Hadley Centre, said more studies and more data were needed to fully understand the role of clouds and aerosols. “This figure has the potential to be incredibly alarming if it is right,” she said. “But as a scientist, my first response is: why has the model done that? We are still in the stage of evaluating the processes driving the different response.” Richard Betts Professor, Met Office Hadley Centre & University of Exeter: It’s correct to have included this statement from a leading authority on the new models, but the headline and opening sentence of the article do not reflect the caution given here. “The more we learn, the more fragile the Earth system seems to be and the faster we need to move,” he said. “It gives even stronger argument to step out of this Covid-19 crisis and move full speed towards decarbonising the economy.” Piers Forster Professor, University of Leeds: In fact the more we learn, quite often we find that nature is quite robust, even when trying our best to destroy it, see our CCC blog."
https://science.feedback.org/review/video-from-prageru-makes-several-incorrect-and-misleading-claims-about-climate-change-richard-lindzen/,-2,"PragerU, by Richard Lindzen, on 2020-05-08.",,"""Climate Change: What Do Scientists Say""",,,,"1 – IPCC (2007) Summary: for Policymakers. In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. 2 – IPCC (2014) Climate Change 2014: Summary for Policymakers. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. 3 – Hausfather (2017) The extent of the human contribution to modern global warming is a hotly debated topic in political circles, particularly in the US. Carbon Brief. 4 – Neukom et al. (2019) No evidence for globally coherent warm and cold periods over the preindustrial Common Era. Nature. 5 – Friedlingstein et al (2019) Global carbon budget 2019. Earth System Science Data. 6 – Doney et al (2009) Ocean acidification: The other CO2 problem. Annual Review of Marine Science. 7 – Mbow et al. (2019) IP Food Security. In: Climate Change and Land: an IPCC special report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems. IPCC report. 8- Tubiello et al. (2007). Crop and pasture response to climate change. PNAS. 9 – Nolan et al (2018) Past and future global transformation of terrestrial ecosystems under climate change. Science. 10 – Burke et al (2018) Pliocene and Eocene provide best analogs for near-future climates. PNAS.","Reviewers’ Overall Feedback: Katrin Meissner Professor, University of New South Wales: If you watched this video, you have unfortunately wasted 5 minutes of your day. Richard Lindzen is reiterating a few wrong statements on climate change that have been debunked repeatedly in the past (e.g. “there is no evidence that CO2 emissions are the dominant factor” of climate change)[1,2]. He is also very skilled at presenting a few statements on climate change that are right in a misleading way, so that the overall message becomes wrong (“climate is always changing”, “there are many reasons why the climate changes”). He misrepresents the way the IPCC works. He also claims that there is a significant number of specialists (a whole “group”) sharing his “understanding” of climate science, which is also not true. Patrick Brown Assistant Professor, San Jose State University: There are many inaccuracies contained within the video in question. The text below deals with just the first one of them. At the 8 second mark, Dr. Lindzen claims that the climate has changed “remarkably little” over the past 30 years without any reference to what “remarkably little” is relative to. When put in proper context, it is not true that the climate has changed “remarkably little” over the past 30 years. Over the past 30 years, the global average temperature has warmed by about 0.7 degrees Celsius (red line from 1990 to 2020 in the global temperature dataset below): Source: NASA GISTEMP: https://data.giss.nasa.gov/gistemp/graphs_v4/ Now we want to put this 0.7 degrees Celsius warming over 30 years in context of other large climate changes in earth’s history. Some of the largest and fastest global climate changes in the geological record are associated with the Milankovitch cycles. The most recent Milankovitch cycle transition was that from the last glacial maximum about 20,000 years ago (when about a mile of ice was on top of Boston) to the Holocene climate starting about 10,000 years ago and this transition was characterized by a global warming of about 5 degrees Celsius. Thus, this rather dramatic climate change was characterized by a rate of change of 5 degrees Celsius over 10,000 years or 0.005 degrees Celsius per year[9]. Now we can put the global warming of the past 30 years in context. 0.7 degrees Celsius over 30 years is 0.023 degrees Celsius per year. So the warming of the past 30 years has been about 5 times (0.023/0.005 = 4.6) faster than the warming that occurred over the transition from the last glacial maximum to the preindustrial climate. I have made an animation placing contemporary global warming in the context of previous climate changes: Contemporary Global Warming placed in geological context. https://t.co/DMuiKptjPi pic.twitter.com/WI4jRQhrs4 — Patrick T. Brown (@PatrickTBrown31) August 20, 2018 Below is a static graph of a similar analysis: Source: Burke et al (2018)[10]. Additionally, Dr. Lindzen implicitly supports his claim of “remarkably little” warming with a misleading figure. At the 18-second mark, the video shows a graph of what I believe are satellite-derived monthly temperature anomalies. However, this time period has been cherry-picked to show “remarkably little” warming. Below is their graph overlain on the full satellite record (which began in 1978). The full satellite record shows that extending their graph in either direction (forward or backward in time) would reveal a clear warming trend. Source: University of Alabama Huntsville: https://www.nsstc.uah.edu/climate/ When these satellite derived temperature products (RSS and UAH in the graph below) are displayed as annual values and plotted on the same axis as the instrumental temperature datasets (Met Office, NASA and NOAA in the graph below), they largely agree with each other. In particular, they all show the same large (in a geological context) rate of warming over the past several decades: Source: Carbon Brief. Overall, Dr. Lindzen makes both a verbal claim and a visual claim that the rate of contemporary global warming is small, and both claims are false. Sara Vicca Postdoctoral research fellow, University of Antwerp: CO2 is indeed fundamental for most life on Earth. Plants need CO2 to grow and they are at the base of the food chain. However, this fact is often abused to claim that increasing CO2 concentrations is mainly a good thing. Although plant growth is often stimulated by increasing CO2 concentrations, CO2 also causes ocean acidification and warms the planet, thereby generating a cascade of effects from melting of glaciers and sea level rise to altered precipitation patterns and increasing frequency and intensity of extreme weather events such as heatwaves and droughts[5-8]. These in turn threaten water and food supplies, and as climate change progresses, this is also likely to undo much of the beneficial effect that CO2 has on plant growth[8]. I would say this claim is thus misleading in the context of this video."
https://science.feedback.org/review/low-solar-activity-has-little-effect-on-earths-climate-contrary-to-claim-in-the-sun/,Incorrect,"The Sun, Chris Pollard, 2020-05-13","""The sun has gone into ‘lockdown’ which could cause freezing weather, earthquakes and famine, say scientists""",,Incorrect: Solar activity cycles have little effect on the Earth’s climate and are not related to earthquakes or volcanic eruptions.  Inadequate support: The article does not provide references to support predictions about solar activity and its effects on climate.,"Although solar activity is currently in a quiet phase, this is typical of the 11-year cycle in the Sun’s energy output. The effect of low solar activity on the Earth’s climate is small compared to global warming caused by greenhouse gas emissions."," “The sun has gone into ‘lockdown’ which could cause freezing weather, earthquakes and famine, say scientists. Nasa scientists fear it could be a repeat of the Dalton Minimum, which happened between 1790 and 1830 — leading to periods of brutal cold, crop loss, famine and powerful volcanic eruptions.”",1 – Feulner et al (2010) On the effect of a new grand minimum of solar activity on the future climate on Earth. Geophysical Research Letters. 2 – Love et al (2013) Insignificant solar‐terrestrial triggering of earthquakes. Geophysical Research Letters. 3 – Benestad (2013) Are there persistent physical atmospheric responses to galactic cosmic rays? Environmental Research Letters. 4 – Palle et al (2016) Earth’s albedo variations 1998–2014 as measured from ground‐based earthshine observations. Geophysical Research Letters.,"Review: This claim appeared in multiple outlets including The Sun, PJ Media, and the New York Post, and has been viewed on Facebook more than 40.5 million times in the past week. This claim, along with several others made in the article, contradict or are unsupported by scientific evidence. While the Sun varies in energy output in approximately 11 year cycles, this cycle has little effect on Earth’s climate, particularly compared to global warming caused by greenhouse gas emissions[1]. The claim “Nasa scientists fear it could be a repeat of the Dalton Minimum, which happened between 1790 and 1830 — leading to periods of brutal cold, crop loss, famine and powerful volcanic eruptions,” is unsupported and contrasts with scientific evidence showing no relationship between low solar activity and Earth’s climate[1]. The latest sun cycle forecast data shows a solar minimum occurring this year (see figure below), but there is no evidence of a prolonged “grand minimum” occurring, as the reviewers explain below. Source: NOAA. The article relies on a quote from Dr. Tony Phillips stating that “Solar Minimum is under way,” but the quote does not mention temperature, earthquakes, or famine. Contrary to this claim, NASA explains, “the current scientific consensus is that long and short-term variations in solar activity play only a very small role in Earth’s climate. Since 1750, the warming driven by greenhouse gases coming from the human burning of fossil fuels is over 50 times greater than the slight extra warming coming from the Sun itself over that same time interval.” A study evaluating the relationship between low solar activity and Earth’s climate found that a grand solar minimum may offset -0.3°C at most, a decrease much smaller than the warming expected from greenhouse gas emissions (see figure below)[1]. Figure – Rise of global temperature for two different emission scenarios (A1B, red, and A2, magenta). The dashed lines show the slightly reduced warming in case a Maunder-like solar minimum should occur during the 21st century. The blue line represents global temperature data. Source: PIK. The article is misleading to readers by suggesting the volcanic eruption of Mount Tambora in 1815 was linked to the Sun’s activity. The article claims, “NASA scientists fear it could be a repeat of the Dalton Minimum, which happened between 1790 and 1830 — leading to periods of brutal cold, crop loss, famine and powerful volcanic eruptions…On April 10, 1815, the second-largest volcanic eruption in 2,000 years happened at Mount Tambora in Indonesia, killing at least 71,000 people.” However, as the reviewer explains below, this eruption was not related to solar activity and the article provides no support for its claim of a link. There is also no scientific evidence to support the claim that a solar minimum can cause earthquakes, as claimed in the headline[2]. According to the USGS, “it has never been demonstrated that there is a causal relationship between space weather and earthquakes. Indeed, over the course of the Sun’s 11-year variable cycle, the occurrence of flares and magnetic storms waxes and wanes, but earthquakes occur without any such 11-year variability.” Although solar activity is currently low, this is typical of the 11-year cycle. There is no scientific evidence to support the claims that low solar activity can cause freezing weather, famine, earthquakes, and volcanic eruptions. UPDATE (22 May 2020):After this post was published, the headlines and bodies of articles in The Sun and the New York Post were corrected to clarify that low solar activity does not cause brutal cold, crop loss, famine, or volcanic eruptions. These articles now include disclaimers saying previous versions of the articles included misleading claims. UPDATE (27 May 2020):After this post was published, the headline and body of an article in The Daily Mail was corrected to clarify that solar activity cycles have little effect on the Earth’s climate. Scientists’ Feedback: Rasmus Benestad Senior scientist, The Norwegian Meteorological institute:There are indeed some indications that the solar activity is declining, e.g. as seen from the sunspot number during the most recent solar max in ~2014. Figure – Updated sunspot record shows a lower number of sunspots during the most recent solar maximum. The solar minima, on the other hand, tend to be on a similar level with few sunspots, and we are currently heading into a solar minimum as is typical every ~11 years. Source: http://sidc.oma.be/silso/DATA/SN_m_tot_V2.0.txt Claim: “Sunspot counts suggest it is one of the deepest of the past century. The sun’s magnetic field has become weak, allowing extra cosmic rays into the solar system.” This sentence is also consistent with the sunspot record, but the solar max in ~1885 was almost on the same level as the recent solar max in ~2014. The solar maxima in ~1805 and ~1817 were at lower levels, however. Claim: “Nasa scientists fear it could be a repeat of the Dalton Minimum, which happened between 1790 and 1830 — leading to periods of brutal cold, crop loss, famine and powerful volcanic eruptions.” The implication of this sentence is not supported by science. In 1815, there was a big volcanic eruption (Tambora in Indonesia) which was responsible for a drop of temperature (the year without summer) and poor crop yields, but it was completely unrelated to the solar activity. There is anecdotal evidence for low temperatures in Europe in 1816, but there is little data from the rest of the world available from that time. The longest ongoing instrumental temperature record is the Central England Temperature (CET), shown in the figure below, and it suggests that while 1816 was cold, there were also other years with colder or comparable summer temperatures. There is little reliable information to say whether the cold summers in England are part of a global phenomenon. We know today that England can have a cold summer without the rest of the planet being cold. Figure – Central England Temperature: June-July-August mean. Source: http://hadobs.metoffice.com/hadcet/cetml1659on.dat Claim: “Temperatures plummeted by up to 2C over 20 years, devastating the world’s food production.” The implications of this sentence are misleading since it suggests that these changes are due to changes in solar activity. There are no convincing links between solar activity/cosmic rays and climate variations[1,3]. If there were a strong connection between solar activity and climate, that would indeed be interesting, as it would suggest that our climate is quite sensitive to external forcing. The climate sensitivity is influenced by amplifying feedback mechanisms, such as changes in snow/ice-cover (changed albedo) or changes in atmospheric humidity (water vapour is a greenhouse gas). However, many of these feedback mechanisms act on changes in temperature, and would play a role for any type of forcing—also anthropogenic forcing. In that sense, there is no reason to think that a sensitivity to solar activity would rule out sensitivity to greenhouse gases—quite the opposite. The global warming trend in the last decades cannot be explained in terms of solar activity because there has not been any trend in solar activity. There is additional evidence that the trend cannot be due to galactic cosmic rays (GCRs) because (a) there has been no trend in GCRs, (b) the warming has been strongest during the polar night (winter in the Arctic) and at nighttime, where the mechanisms proposed for GCR is absent (changes in cloudiness and albedo), (c) there is no trend in the global albedo[4]. Georg Feulner Senior Scientist, Potsdam Institute for Climate Impact Research (PIK): Claim: “leading to periods of brutal cold, crop loss, famine and powerful volcanic eruptions.” While there were volcanic eruptions coinciding with the Dalton Minimum, there is no evidence whatsoever to suggest that solar activity causes volcanic eruptions! The volcanic eruptions during that time, and in particular the eruption of the Tambora in 1815, did cause the climate to cool and affected harvests, but this had little to do with the low solar activity of the Dalton Minimum. Studies also show that most of the cooling was due to volcanic aerosols, and that even a prolonged solar minimum could not offset future warming from human greenhouse gas emissions[1]. Claim: “On April 10, 1815, the second largest volcanic eruption in 2,000 years happened at Mount Tambora in Indonesia, killing at least 71,000 people. It also led to the so-called Year Without a Summer in 1816 — also nicknamed “eighteen hundred and froze to death” — when there was snow in July.” Again, these are the effects of the Mount Tambora eruption which has no connection to the low solar activity at that time. Doug Biesecker, Space Weather Prediction Center, NOAA:[Comment from a previous evaluation of a similar claim in February 2020.][Dr. Biesecker was co-chair of NOAA’s Solar Cycle 25 Prediction Panel.] There is no evidence we are headed into a grand minimum. With Cycle 25 predicted to be similar to Cycle 24 [2009-2020], we do not see anything approaching a grand minimum, at least not in the near future. What we cannot say is what Cycle 26 will look like—mainly because no one has a demonstrated method for predicting that far ahead. As for solar minimum, the panel only addressed the timing of minimum, not the intensity. However, it would be fair to say that no one on the panel expects an extreme minimum. Based on the panel prediction of minimum occurring in April of 2020 (+/-6 months), we would expect this minimum to be very similar to the last minimum between Cycles 23 and 24."
https://science.feedback.org/review/the-global-polar-bear-population-is-threatened-by-loss-of-sea-ice-contrary-to-pragerus-video-claim/,Incorrect,"PragerU, Anonymous, 2020-05-05",The polar bear population has been growing. Polar bears are thriving even where sea ice is diminishing.,,Cherry-picking: There is no scientific evidence that the global polar bear population is growing and there is evidence that several subpopulations are declining. Only two of the 19 polar bear subpopulations are likely increasing in size. The claim does not discuss data from other subpopulations that are declining or stable.  Incorrect: The claim that “Polar bears are thriving even where sea ice is diminishing” runs counter to scientists’ understanding: sea ice loss due to climate change is recognized as the most important threat to the long-term survival of polar bears.,There is no scientific evidence that the global polar bear population is growing in size. Climate change induced losses in sea ice habitat is the most important threat to polar bear survival. Two polar bear subpopulations have already been negatively impacted by sea ice loss.,The polar bear population has been growing. The polar bear population is higher than it's been in over 50 years. Polar bears are thriving even where sea ice is diminishing.,1 – Stirling et al (2012) Effects of climate warming on polar bears: a review of the evidence. Global Change Biology. 2 – Stern et al (2016) Sea-ice indicators of polar bear habitat. The Cryosphere. 3 – Regehr et al (2016) Conservation status of polar bears (Ursus maritimus) in relation to projected sea-ice declines. Biology Letters. 4 – Derocher et al (2013) Rapid ecosystem change and polar bear conservation. Conservation Letters. 5 – Hunter et al (2010) Climate change threatens polar bear populations: a stochastic demographic analysis. Ecology. 6 – Bromaghin et al (2015) Polar bear population dynamics in the southern Beaufort Sea during a period of sea ice decline. Ecological Applications. 7 – Lunn et al (2016) Demography of an apex predator at the edge of its range: impacts of changing sea ice on polar bears in Hudson Bay. Ecological Applications. 8 – Regehr et al. (2018) Integrated population modeling provides the first empirical estimates of vital Rates and abundance for polar bears in the Chukchi Sea. Scientific Reports. UPDATES: 19 May 2020: This post was updated to correct the publication dates for two references.,"Review: The claims appeared in a Facebook video by PragerU in May 2020, and has received more than 1 million views since it was published. There is no scientific evidence that the entire polar bear population has been growing, contrary to what this video claims. Of the 19 subpopulations measured by the IUCN Polar Bear Specialist Group, only two are likely increasing over the short-term. Currently, sea ice loss due to climate change is the most important threat to polar bears, contradicting the claim that “polar bears are thriving even where sea ice is diminishing”[1-3]. The global polar bear population is currently estimated to be approximately 20,000 – 25,000 bears, distributed among 19 subpopulations[4]. There is no scientific evidence that the global polar bear population is growing as the video claims, as the reviewers describe below. In 2019, two small polar bear subpopulations were estimated to have increased, four declined, and five were stable. The other subpopulations did not have enough data to demonstrate short or long-term trends (see figure below). Figure—Geographic distribution, size, and trends of 19 polar bear subpopulations measured by the IUCN Polar Bear Specialist Group. Colors reflect subpopulation trends in 2019. Shape and size of the circle represent subpopulation size, measured in number of bears. Adapted from the IUCN Polar Bear Specialist Group. Prior to the late 1970s, data on polar bear populations was limited or non-existent, as described by the reviewers below. During this time, hunting, killing, and capturing polar bears were the biggest threats to their survival until an agreement was signed to control these practices in 1973[4]. This agreement likely led to an increase in the global polar bear population in the 1970s[5]. But as stated in Hunter et al. (2010), “there is no evidence that these increases continued, and such recoveries, where they occurred, are irrelevant to the effects of recent changes in the availability of sea ice.”[5] More recent data from several subpopulations shows stable or declining trends in polar bear population size over time (see figures below). Figure—Estimated size of the Western Hudson Bay polar bear subpopulation using data from capture-recapture models from 1984-2011. From Lunn et al. 2016[7]. Figure—Estimated size of the Chukchi Sea polar bear subpopulation using capture data from 2009-2011, 2013, and 2015-2016. From Regehr et al. 2018[8]. The most important threat to the long-term survival of polar bears is the loss of sea ice habitat due to climate change[1-3]. Polar bears rely on sea ice to hunt seals (their primary prey), mate, establish dens, and move to new regions seasonally[2]. Loss of sea ice is occurring in almost all polar bear subpopulations and has already negatively affected some subpopulations[6,7]. “Long-term monitoring studies in Canada suggest that polar bear body condition, survival and population growth rates are all negatively impacted by declines in the availability of sea ice habitat and there are no data to suggest that polar bears are thriving in areas where sea ice has significantly declined,” said Gabrielle Lamontagne, a communication advisor for Environment and Climate Change Canada. In 17 of the 19 polar bear subpopulations, sea ice is retreating earlier in the spring. Sea ice is advancing later in the fall in 16 subpopulations. For example, in the Hudson Bay subpopulation, scientists found that earlier break-up of sea ice was associated with lower rates of survival for all age classes of female polar bears (see figure below). Figure—Estimated survival of female polar bears aged 1 – 19 years old declines as sea ice breaks up earlier in the year. Live-recapture and dead-recovery data was collected in the Hudson Bay subpopulation from 1984 – 2011. From Lunn et al. 2016[7]. Overall, the claims that the polar bear population is growing and that polar bears are thriving in areas where sea ice diminishing are not supported by scientific evidence. Scientists’ Feedback: Andrew Derocher Professor, University of Alberta: For the claims, and the “inconvenient facts”: “The polar bear population has been growing.” – Incorrect. There are 19 subpopulations of polar bears across the Arctic. Four are likely decreasing (according to the IUCN/SSC Polar Bear Specialist Group – of which I am a member). Five are likely stable and two are likely increasing. The remainder are unknown. However, one of the unknown subpopulations is likely also decreasing but the Government of NWT won’t release the analyses showing that it has declined as well. If one considers the “global” population as if there is 1 population in the Arctic, the claim of “growing” cannot be supported. For the claim that “The polar bear population hasn’t been this high in over 50 years”—well, if one wants to start the numbers at the pre-1973 start point, perhaps this one is OK because while we have zero data on polar bear abundance until the late 1970s, polar bears were commercially harvested until ca. 1973 when the Agreement on the Conservation of Polar Bears was signed that introduced harvest controls. Polar bears, while based on poor or no data, were heavily depleted in the 1950s-1960s. So, from 1970 to 2020, fine, polar bear populations overall increased. This of course ignores areas that have now declined (Western Hudson Bay, Southern Hudson Bay, Southern Beaufort Sea) and M’Clintock Channel that was severely overharvested post-1973. It’s a word game. Past increases were due to harvest controls. Current declines are due to climate change associated loss of sea ice[1,2,3]. For the claim that “Polar bears are thriving even where sea ice is diminishing”—again, this is spin. In Western Hudson Bay, Southern Hudson Bay, and Southern Beaufort Sea, population declines are associated with sea ice loss (lower survival, lower successful reproduction that lead to abundance declines). Some polar bear populations are doing OK and are experiencing some sea ice loss. We know, however, that that pattern cannot be sustained. The Barents Sea polar bears appear to be doing OK yet they are losing sea ice at high rates. Why are they doing OK and others are not? That area has a very large area of continental shelf/shallow water. Polar bear habitat is widespread. It is experiencing the highest rate of sea ice loss in days of cover per decade of the 19 polar bear populations. We’ve just not hit the point where their habitat is affected enough to cause problems. It will happen. Regardless, this area has seen many changes (e.g. loss of maternity den areas, loss of habitat). I worked in the Barents Sea for 7 years—this population will lose with the current trend in sea ice. Ian Stirling Adjunct Professor, University of Alberta: The sources the video cites are nonsense scientifically and, worse, deliberately misrepresent the facts. As for real numerical information on polar bears, if anyone wants to know how much can be said with as much reliability as is possible, they should go to the web site for the IUCN Polar Bear Specialists Group (which I am also a member of). Note on the left hand side there are headings that give estimates and summaries (with references) of knowledge for all the 19 populations. The estimates for some populations are labelled as current, outdated, and nonexistent for others, particularly in Russia, so it is not technically possible to have a “total estimate”. In reality, it is the status and trends of the 19 individual populations that count. Several populations, such as those in western and southern Hudson Bay, and the southern Beaufort Sea are confirmed unequivocally, from long-term data, to have declined significantly as a direct result of climate warming causing steady loss of sea ice[6,7]. Some other populations are likely also declining, just judging from the extent of the steady loss of ice but we lack long-term data with which to make that assessment, and a couple are doing OK, such as Foxe Basin and Davis Straight, and one seems to be increasing (M’Clintock Channel). However, unless we are able to stop global warming and maybe even start to cool the planet, all populations will decline severely and some will be lost forever[5]. The steady loss of sea ice in all subpopulation regions is well summarized by Stern and Laidre[2]. Dr. Derocher and I also published a review a few years ago that gives the state of knowledge about the effects of climate warming on polar bears[1]. READ MORE We wrote a review on a picture published by National Geographic, in which scientists explain that it was unclear whether this particular polar bear was a victim of climate change. In another Climate Feedback review of a Financial Post article, scientists explained that the claim “polar bears are thriving” rather than being threatened by losses in Arctic sea ice misrepresents scientific research on this topic."
https://science.feedback.org/review/article-in-business-insider-accurately-describes-results-from-a-study-estimating-up-to-3-billion-people-could-live-in-much-warmer-temperatures-by-2070/,0.3,"Business Insider, by Sarah Al-Arshani, on 2020-05-05.",,"""3 billion people — up to half the current global population — could be living in unbearable heat in 50 years""",,,,1 – Xu et al (2020) Future of the human climate niche. PNAS. 2 – Riahi et al (2011) RCP 8.5—A scenario of comparatively high greenhouse gas emissions. Climatic Change.3 – Fujimori et al (2017) SSP3: AIM implementation of Shared Socioeconomic Pathways. Global Environmental Change.,"Reviewers’ Overall Feedback: Marten Scheffer Professor, Wageningen University: [Prof. Scheffer was an author of the study that was the topic of this article.] It is slightly misleading to compare the future amount of people under severe climate stress to the current total population, as in the meantime the global population will have grown. It is not wrong, but it somehow suggests half the people get in severe climate trouble whereas it would be one third (for the high end forcing scenario). Steven Sherwood Professor, University of New South Wales: The study does not address temperatures that are “survivable,” only those which humans evidently prefer and thrive in. We know the warmer temperatures are not unsurvivable because people have been surviving in them for millenia. Thus the story is misleading and overhyped. It appears that the fault for this lies more with overzealous statements by some of the ecologists than the journalist who wrote the story. Nonetheless the warmer temperatures will be more difficult and undoubtedly lead to all kinds of problems, and it is valuable to have this new study highlighting that past societies in these climates have not progressed in the same way as those in cooler climates. So I applaud the study and the choice to write about it, they just needed to stay to what they’d actually shown. Andrew King Research fellow, University of Melbourne: Overall, this article provides a fair representation of the study it’s based on. It accurately portrays the study’s main results in the headline, key points and throughout the text. I think the focus of the article on the worst-case scenario ahead of more likely scenarios may not be the most helpful, but this is at least explicit in the article. As Xu et al. note[1], the analyses are statistical associations not process-based understanding of the multiple drivers of the location of human settlements over time. The authors note there are many variables they did not investigate because data were not available; this does not mean the variables are unimportant. Some of these variables are likely also to be associated with geographic location of humans, crops, and livestock. It would be interesting to hear from agricultural specialists about variables related to the geographic location of crops (such as growing degree days, day length, timing of precipitation, and others). The perspectives of anthropologists on the drivers of successful human settlements also would be interesting. The scenario in the main text combines RCP 8.5 and SSP 3, resulting in very high greenhouse gas emissions, leading to greater climate change in 2100 than in other scenarios. The Paris Agreement committed governments to significantly reduce their GHG emissions, decreasing the probability of RCP 8.5."
https://science.feedback.org/review/diesel-cars-are-a-major-source-of-no2-emissions-in-european-cities-contrary-to-online-claim/,Flawed reasoning,"Tichys Einblick, Holger Douglas, 2020-04-12",The drop in NO<sub>2</sub> content has only been “slight”. So it cannot be the evil diesel engine cars that are “choking” our cities.,,"Inadequate support: The article does not provide any scientific evidence to support its claims about recent trends in car traffic and NO2 emissions in Stuttgart, Germany.  Flawed reasoning: The argument that diesel engine cars are not polluting cities because NO2 concentrations haven’t changed even though traffic has declined is flawed. Studies show that diesel car emissions are a major contributor of nitrous oxide emissions in European cities. ","Road transport accounts for almost half of nitrous oxide emissions in European cities, including Stuttgart, Germany. Scientific studies have shown that diesel-fueled vehicles are the primary source of nitrous oxide emissions from road transport in Europe.","Although car traffic in the German city of Stuttgart has decreased significantly due to COVID-19, the drop in NO<sub>2</sub> content has only been “slight”. So it cannot be the evil diesel engine cars that are “choking” our cities.","1 – Driscoll et al. (2018) Real world CO2 and NOx emissions from 149 Euro 5 and 6 diesel, gasoline and hybrid passenger cars. Science of the Total Environment. 2 – Degraeuwe et al. (2017) Impact of passenger car NOx emissions on urban NO2 pollution – Scenario analysis for 8 European cities. Atmospheric Environment. 3 – Sims et al. (2014) Transport. In: Climate Change 2014: Mitigation of Climate Change. Contribution of Working Group III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. 4 – UNEP 2013. Drawing down N2O to protect climate and the ozone Layer. A UNEP Synthesis Report. United Nations Environment Programme (UNEP). 5 – Reay et al. (2012) Global agriculture and nitrous oxide emissions. Nature Climate Change. 6 – Khaniabadi et al. (2016) Exposure to PM10, NO2, and O3 and impacts on human health. Environmental Science and Pollution Research. 7 – Pleijel et al. (2016) A method to assess the inter-annual weather-dependent variability in air pollution concentration and deposition based on weather typing. Atmospheric Environment.","Review: This claim appeared in Tichys Einblick and NoTricksZone in April 2020 and has been shared over 8,500 times since it was published. The article does not provide scientific evidence to support their claims that car traffic has “significantly” decreased and NO2 has only slightly declined in response to the novel coronavirus (SARS-CoV-2). The argument that reductions in car traffic, but stable NO2 levels mean that diesel cars do not pollute cities is flawed. Although NO2 concentrations can fluctuate over time and space, several scientific studies that measured sources of NO2 emissions in European cities demonstrate that road traffic and diesel cars, in particular, are major contributors of NO2 emissions[1,2,3]. Nitrous oxides (NOx) are a family of air pollutants that includes seven chemical compounds. According to a report published by the United Nations, nitrogen oxide is “the most significant ozone-depleting substance emission and the third most important greenhouse gas.”[4] Nitrous oxide (N2O) and nitrogen dioxide (NO2) are the most prevalent pollutants in the air. These compounds are produced by human activities, including agriculture, fuel combustion, and industrial processes[4,5]. By diminishing air quality, nitrous oxides can impact human health. For example, Khaniabadi et al. (2016) state, “approximately 5–7% of the lung cancers among ex-smokers and non-smokers can be associated with exposure to high levels of air pollutants containing NO2 or vicinity to roads with heavy-traffic.”[6] As described by the reviewer below, NO2 concentrations are challenging to measure over short time periods (e.g. weekly, monthly) because they are influenced by season, weather patterns (e.g. wind, temperature), and man-made emissions[3,7]. Despite this variation, scientific studies have found that road traffic accounts for 47% of annual nitrous oxide emissions in European cities, including Stuttgart (see figure below). Figure—Annual nitrous oxide emission (NOx) of 30 European cities. Pie charts show the share of emissions attributed to different sources. Source EU Science Hub. The article in which the claim appeared does not specify how car traffic and NO2 concentrations were measured in Stuttgart or over what time period, providing no adequate support for the claim that car traffic has declined “significantly” or that “the drop in NO2 content has only been ‘slight’.” A separate article claims there has been a 37% reduction in car traffic at the Am Neckartor station in Stuttgart when comparing data from March 2020 to March 2019. While these estimates support a decline, there is still car traffic on the road and this data is only from a single station. Furthermore, the claim that diesel cars do not pollute cities contradicts available scientific evidence showing diesel cars are responsible for the vast majority of NO2 emissions in urban environments. To determine the amount of air pollution attributed to different vehicle types, O’Driscoll et al (2018) measured real world NOx emissions from diesel, gasoline, and hybrid passenger vehicles sold in Europe using portable emissions measurement systems. Diesel cars produced, on average, 8 – 11 times more NOx in urban environments than gasoline cars, depending on the European emissions standard category (see figure below). The authors also estimated that, “gasoline vehicles delivered an 86 – 96% reduction in NOx emissions compared to diesel cars.”[1] Figure—In urban areas, diesel cars (green) emit 8 – 11 times more NOx than gasoline cars (blue). Cars are grouped by European emission standards (G6: Euro 6 Gasoline, G5: Euro 5 Gasoline, D6: Euro 6 Diesel, D5: Euro 5 Diesel). Adapted from O’Driscoll et al. (2018)[1]. This study is consistent with data from across 33 European cities, which identified diesel cars as the primary source of NOx emissions from road traffic (see figure below). Figure—Across Europe, diesel cars are the major source of annual nitrous oxide (NOx) emissions from road traffic. Source EU Science Hub. Overall, these data directly contradict the claim that diesel cars are not polluting cities. Scientists’ Feedback: Tim Butler Research Group Leader, Institute for Advanced Sustainability Studies: Firstly, it’s very well established that urban NO2 concentration is highly influenced by both weather conditions and nearby emissions. For example, on a still day, pollution will accumulate, leading to higher concentrations near the emission sources, while on a windy day, pollution will be quickly blown away, leading to relatively lower concentrations near the emission sources. The chemical lifetime of NO2 is also shorter during warm, sunny days, and longer in winter, when the days are shorter and darker. For these reasons, European air quality legislation specifies ambient NO2 limit values in terms of the annual mean concentration. By measuring the annual mean, the seasonal variations and the short term fluctuations due to weather are averaged out, and a more reliable indication of the exposure at the measurement locations is obtained. Man-made NO2 emissions are primarily from combustion sources. This combustion may be in industrial facilities, residential heating units, or the internal combustion engines which still power most vehicles. The relative mix of these sources can vary between cities, but on average road traffic is thought to account for about half of the man-made NO2 in most European cities. Regarding the claims in the article, these are vague and hard to verify. The reduction in traffic in Stuttgart is supposed to have decreased “significantly”, but this is not quantified in the article. The article also claims that the air quality has “hardly changed”, but does not specify what this means. Over which period? Compared to what? By how much exactly? The article mentions a pre-restriction measurement of 40 µg/m3 NO2 concentration at the station Am Neckartor (only for a 2-month period), but doesn’t give a number for post-restriction. Without many actual numbers backing things up, the reasoning behind the claims in the article appears weak. I visited the website of the Amt für Umweltschutz of the city Stuttgart, to look for some recent reports on traffic and air quality, and found the following article. Apparently the amount of traffic at the Am Neckartor site has reduced by about a third due to the restrictions. Perhaps that’s “significant”, but it’s not a complete shutdown. This article also discusses a reduction in the measured NO2 concentration at that site, and gives a number of possible reasons, including the Coronavirus restrictions. Rightly, this article is cautious about interpreting these short-term variations in NO2, since the legal limit value is defined as an annual average, and we are only in April now. 2020 still has 8 months to go."
https://science.feedback.org/review/claim-that-co2-is-cooling-the-planet-is-misleading-anthropogenic-co2-emissions-overall-cause-global-warming/,Imprecise,"Express, Sebastian Kettley, 2020-02-18",Global warming slowing down? 'Ironic' study finds more CO<sub>2</sub> has slightly cooled the planet,,"Flawed reasoning: Human-caused CO2 emissions can enhance plant growth and increase absorption of atmospheric CO2 that causes global warming, thus acting as a negative feedback. This negative feedback can reduce the amount of global warming, but has not cooled the planet as claimed in this headline.  Misrepresents source: The review paper the claim is based on does not show that CO2 has “cooled the planet”, but that CO2 absorption by plants leads to a smaller global temperature increase than would otherwise occur.","Human-caused CO2 emissions are responsible for approximately 100% of the global warming trend observed since 1950. Although enhanced plant growth absorbs some of the CO2 emitted by human activities, reducing the amount of global warming that can occur, this negative feedback has not caused warming to slow in recent years.","Global warming slowing down? 'Ironic' study finds more CO<sub>2</sub> has slightly cooled the planet[...] The process, known as evapotranspiration, occurs when plants consume the heat-trapping greenhouse gas and release water. Much like humans sweating on a hot day, evapotranspiration can have a cooling effect on the air. In other words, with more carbon dioxide feeding plant growth, the planet is slightly cooler than otherwise expected.","1 – Piao et al (2019) Characteristics, drivers and feedbacks of global greening. Nature Reviews Earth & Environment. 2 – Zhu et al. (2016) Greening of the Earth and its drivers. Nature Climate Change. 3 – Piao et al (2006) Effect of climate and CO2 changes on the greening of the Northern Hemisphere over the past two decades. Geophysical Research Letters. 4 – Yuan et al (2017) Vegetation changes and land surface feedbacks drive shifts in local temperatures over Central Asia. Scientific Reports.5- De Graaff et al. (2006) Interactions between plant growth and soil nutrient cycling under elevated CO2: a meta-analysis. Global Change Biology.","Summary: The claim, which appeared as the headline of an article published by Express in February 2020, uses flawed reasoning to argue that the rate of global warming has slowed because plants absorbed CO2 emitted by human activities in some regions around the world. Global land and ocean temperatures continue to rapidly increase, contrary to the article headline of a change in the rate of warming (see figure below). Figure—Global temperature anomaly data relative to the 20th century average temperature from the Global Historical Climatology Network-Monthly data set and International Comprehensive Ocean-Atmosphere Data Set. These data sets show consistent global warming trends. From NOAA. The article misrepresents findings of the review paper it is based on. The paper describes how CO2 uptake by plants acts as a negative feedback, reducing the potential rate of warming by removing some CO2 from the atmosphere[1,2]. Increased plant growth can also reduce local land surface temperatures in some regions where the cooling effects of evapotranspiration outweigh the warming effects of greener canopies reflecting less sunlight back to space. As described in Piao et al (2019), “In warm regions such as the tropics and subtropics, evaporative cooling effects are generally larger than albedo warming effects, leading to a net cooling effect when vegetation greenness increases.”[1] In other regions, albedo warming effects outweigh evaporative cooling, increasing local land surface temperatures[1,3,4]. According to the article, Jarle Bjerke of the Norwegian Institute for Nature Research explained: “It is ironic that the very same carbon emissions responsible for harmful changes to climate are also fertilising plant growth which in turn is somewhat moderating global warming.” Although this negative feedback has lessened the temperature increase of global warming caused by anthropogenic CO2 emissions (“somewhat moderating global warming”), it has not “cooled the planet” or caused a recent reversal in temperature trend, as claimed in the article’s headline. While the headline of the Express article is wrong in claiming this feedback cools the planet, the body of the article gets it right when saying “with more carbon dioxide feeding plant growth, the planet is slightly cooler than otherwise expected.” This is not a new discovery, but a long-understood function of the Earth’s carbon cycle—a portion of the CO2 we emit is absorbed by land plants and by the ocean rather than accumulating in the atmosphere. Finally, greening effects of anthropogenic CO2 are expected to weaken or disappear over time with continued global warming[1,3]. UPDATE (27 April 2020): After this post was published, the headline of the article in Express was corrected. The body of the Express article was also edited to clarify that the planet is not cooling. Specifically, the author clarified that the greening trends caused by CO2 emissions are only observed in certain parts of the world, such as the tropics and sub-tropics. He added the following sentences, “Although the effect has not cooled the planet, the planet is slightly cooler than otherwise expected,” and “Unfortunately, the overall effects of CO2 emissions are overwhelmingly contributing to the planet’s rising temperatures.” Finally, he clarified that greening trends are expected to decline over time by adding, “In time, however, the positive effects of CO2 are expected to weaken in the face of human-led global warming.”"
https://science.feedback.org/review/human-activities-have-dramatically-increased-atmospheric-co2-levels-causing-imbalances-in-the-global-carbon-cycle/,Incorrect,"I Love Carbon Dioxide, Cole Ryan, 2020-04-12",Human additions of CO<sub>2</sub> are in the margin of error of current measurements and the gradual increase in CO<sub>2</sub> is mainly from oceans degassing as the planet slowly emerges from the last ice age.,,"Factually inaccurate: Human activities have increased atmospheric CO2 levels from 280 ppm to more than 400 ppm since industrialization, which is an increase greater than the margin of error of current measurements. Oceans presently serve as a sink for CO2, not a source.  Misleading: Humans have caused an unprecedented rise in atmospheric CO2 levels in the last 800,000 years. This is because the natural flows in the global carbon cycle were previously in balance. ","Atmospheric CO2 has increased rapidly as a result of human activities. Although human-caused emissions of CO2 are small relative to natural flows into and out of the atmosphere, the human contribution has caused an imbalance in the global carbon cycle that jeopardizes land and ocean ecosystems.",Human additions of CO<sub>2</sub> are in the margin of error of current measurements and the gradual increase in CO<sub>2</sub> is mainly from oceans degassing as the planet slowly emerges from the last ice age.,"1 – IPCC (2007) Summary for Policymakers. In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. 2 – IPCC (2014) Climate Change 2014: Summary for Policymakers. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. 3 – Gruber et al (2019) The oceanic sink for anthropogenic CO2 from 1994 to 2007. Science. 4 – Friedlingstein et al (2019) Global carbon budget 2019. Earth System Science Data. 5 – Doney et al (2009) Ocean acidification: The other CO2 problem. Annual Review: of Marine Science.6 – Zhao et al (2006) Estimating uncertainty of the WMO mole fraction scale for carbon dioxide in air. Journal of Geophysical Research.","Summary: The claim appeared in multiple outlets, including Watts Up With That, the Daily Signal, and a Facebook post published by I Love Carbon Dioxide in April 2020. While human additions of CO2 are small relative to natural processes, atmospheric CO2 measurements are currently much higher than pre-industrialization CO2 levels and not within the “margin of error of current estimates,” as described by the reviewers below[1,2]. The ocean does release CO2, but scientific evidence demonstrates that oceans have absorbed approximately 23% of global anthropogenic CO2 emissions since the Industrial Revolution, thus serving as a net sink rather than a source of CO2[3,4]. This claim also fails to recognize that human-induced CO2 emissions have caused imbalances in the global carbon cycle. Pre-industrialization atmospheric CO2 levels were around 280 parts per million (ppm)[2]. Since 1950, the burning of fossil fuels, agricultural development, and other human-caused land-use changes have led to steady increases in atmospheric CO2. According to the IPCC, “This has led to atmospheric concentrations of carbon dioxide, methane, and nitrous oxide that are unprecedented over at least the last 800,000 years.”[1,2]Today, atmospheric CO2 exceeds 400 ppm, as shown in the figure below. Figure—The Keeling Curve, a daily record of global atmospheric CO2, shows relatively stable CO2 concentrations from 1700 to 1950, as measured by ice-cores. After 1950, CO2 concentrations rose rapidly from 300 to over 400 ppm, as measured at the Mauna Loa Observatory. From Scripps Institute of Oceanography. Pre-industrialization atmospheric CO2 levels remained relatively constant because the global carbon cycle was balanced. In other words, the amount of CO2 being released into the atmosphere from natural sources, such as the ocean and respiring organisms, was balanced by the amount of CO2 absorbed from the atmosphere. Human-caused increases in CO2 emissions have created an imbalance in the global carbon cycle, where more CO2 is being released than can be absorbed by natural carbon sinks (see figure below). Excess CO2 in the atmosphere warms the planet and excess CO2 in the oceans causes acidification that jeopardizes marine ecosystems[1,2,5]. Figure—The global carbon cycle from 2009 to 2018 shows that human contributions to atmospheric CO2 outweigh the amount of carbon cycled each year, leading to an annual budget imbalance of 2 GtCO2. From The Global Carbon Budget 2019. Scientists’ Feedback: Peter Landschützer Group Leader, Max Planck Institute for Meteorology: First of all, the claim that current changes in atmospheric CO2 are within the uncertainty of measurements is absurd. Since pre-industrial times atmospheric CO2 levels increased from roughly 280 ppm to now roughly 412 ppm (globally on January 2020) with growth rates currently exceeding 2 ppm/yr. These atmospheric CO2 (as well as other trace gas) measurements are highly accurate with errors estimated at 0.07 ppm[6]. Secondly, the claim that the increase results as “the Planet emerges from the last ice age” is wrong for multiple reasons. Firstly, ice-core atmospheric CO2 records suggest that such a strong increase (from 280ppm to 412 ppm) is unprecedented in the last 800,000 years. Secondly, these records also show that the speed at which atmospheric CO2 increases is unprecedented in the ice-core record history. Finally, the ocean degassing CO2 is causing this “gentle and welcome” increase is fundamentally wrong and not supported by observations. While the anthropogenic perturbation might be small compared to the large natural carbon fluxes in the ocean , they are well detectable from measurements[1,2]. Current science suggests that the ocean is taking up (NOT releasing) roughly 2.5 PgC/yr of carbon from the atmosphere which corresponds to roughly 23% of annual human CO2 emissions[3,6]. This is supported by observation-based estimates using the partial pressure of CO2 collected in the Surface Ocean CO2 Atlas, repeat hydrography measurements of the dissolved inorganic carbon content, and estimates based on atmospheric inversions[1,4]. In summary, there are multiple, independent measurement-based flux estimates that highlight that the ocean is a significant net CO2 sink. [Comment from a previous evaluation of a similar claim.] Global human emissions are indeed only a small percentage of what ecosystems cycle, but the reasoning is completely flawed. Regarding the impact on climate, it is the net emissions that matter, not the amount of carbon that is being cycled over and over. Terrestrial ecosystems take up and re-emit about 12 times more CO2 than humans emit, and oceans cycle about 9 times more CO2 than we emit. BUT! This carbon uptake and release is more or less balanced at the annual scale, and net ecosystem emissions are even negative. Without these ecosystems, atmospheric CO2 concentration would have risen even more as a consequence of fossil fuel burning; the CO2 concentration in the air would already be around 550 ppm (instead of the current ~400 ppm). Hence, it is absolutely misleading to compare amounts of CO2 cycling through the ecosystems with human CO2 emissions in this context. If anything, the CO2 cycling through the ecosystems should be taken as a reason to safeguard them: if we lose these carbon sinks, CO2 in the air will increase no matter what we do."
https://science.feedback.org/review/human-induced-increases-in-greenhouse-gases-are-the-primary-driver-of-global-warming-contrary-to-claims-in-cfact-article/,Incorrect,"CFACT, Jay Lehr, 2020-04-08",They tell us that we are the primary forces controlling earth temperatures by the burning of fossil fuels and releasing their carbon dioxide. I hope my readers can recognize the absurdity of their claims. … increasing sunspots are linked to increases in earth temperature,,Incorrect: Anthropogenic increases in greenhouse gas emissions account for 100% of the rapid global warming trends observed after 1950. Solar forcing cannot exclusively explain climate change patterns. Inadequate support: None of the article’s claims that argue the Sun is responsible for current global warming are supported by published research. ,The effects of CO2 and other greenhouse gas emissions far outweigh the effects of solar forcing on global warming. 100% of the global warming trends observed after 1950 can be attributed to anthropogenic factors.,They tell us that we are the primary forces controlling earth temperatures by the burning of fossil fuels and releasing their carbon dioxide. I hope my readers can recognize the absurdity of their claims. … increasing sunspots are linked to increases in earth temperature.,"1- Feldman et al (2015) Observational determination of surface radiative forcing by CO2 from 2000 to 2010. Nature. 2 – Santer et al (2017) Tropospheric warming over the past two decades. Scientific Reports. 3 – Hausfather (2017) The extent of the human contribution to modern global warming is a hotly debated topic in political circles, particularly in the US. Carbon Brief. 4 – IPCC, 2013: Summary for Policymakers. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change 5 – Li et al (2018) Multiresolution analysis of the relationship of solar activity, global temperatures, and global warming. Advances in Meteorology.","Summary: The claim appeared in an article published by CFACT in April 2020. This claim directly contradicts ample scientific evidence showing that human-caused increases in greenhouse gas emissions, such as CO2, have been the primary driver of global warming[1,2]. Feldman et al (2015) demonstrate that “increasing atmospheric CO2 concentrations between 2000 and 2010 have led to increases in clear-sky surface radiative forcing,” (as seen in the figure below)[1]. When radiative forcing is positive, the Earth absorbs more energy from the Sun than it radiates back to space, causing warming. The authors describe that “Fossil fuel emissions and fires contributed substantially to the observed increase… If CO2 concentrations continue to increase at the current mean annual rate of 2.1 ppm per year, these spectroscopic measurements will continue to provide robust evidence of radiative perturbations to the Earth’s surface energy budget due to anthropogenic climate change.” Figure—Increases in CO2 concentrations measured by CarbonTracker 2011 (CT2011) have led to increases in CO2 surface forcing observed at experimental sites in the continental South Great Plains (SGP). From Feldman et al. 2015[1]. Anthropogenic drivers of global warming far outweigh the effects of solar forcing[3,4]. As described in the 2013 IPCC report, “Greenhouse gases contributed a global mean surface warming likely to be in the range of 0.5°C to 1.3°C over the period 1951 to 2010. The contribution from natural forcings is likely to be in the range of −0.1°C to 0.1°C.” These findings contrast with claims made in the CFACT article that the shape of the Earth’s orbit, tilt of the Earth relative to the Sun, and the Sun itself are the main drivers of current climate change. While these mechanisms can cause climate changes over long time periods (e.g. in 20,000 and 100,000 year cycles), these processes occur too slowly to drive patterns of global warming observed in the past 100 years. Specifically, the article claims that “increasing sunspots are linked to increases in earth temperature,” however, this claim is not supported by scientific evidence. Li et al (2017) analyzed the relationship between the number of sunspots and global warming and found that “solar activity is not a representation of the driving force of the upward trend of global temperature after the industrial age. The Granger causality test results demonstrate that the phenomenon of global warming is caused by excessive CO2 emissions.”[5]. Figure—The monthly average number of sunspots (left) and global surface temperature time series from the Goddard Institute for Space Studies (right). Although sunspot number varies in approximately 11 year cycles, global temperature has steadily increased since 1950. While natural and anthropogenic factors can affect changes in the climate, multiple lines of scientific evidence demonstrate that recent global warming trends can be attributed to human-caused increases in greenhouse gas emissions and not to the Sun[1,3,4]. Scientists’ Feedback: Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: [Comment from a previous evaluation of a similar claim.] Global temperature datasets, developed by a number of independent research groups, show robust warming in the troposphere and at the Earth’s surface. The radiative effect of carbon dioxide has also been observed[1]. Considering multiple lines of evidence, the IPCC concluded that it is “extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century.” More recent analysis of satellite data shows that tropospheric warming from the satellite record is pronounced and cannot be explained by natural climate variability alone[2]. [This comment comes from a previous review of a similar claim.] Careful analysis that attempts to take into account all major factors and their evolution in time indicates that anthropogenic increases in greenhouse gasses account for more than 100% of the observed warming on the century timescale (requiring cancellation from cooling influences). See the summary graphic from Carbon Brief, below. Figure—The estimated role of different factors influencing global surface temperatures from 1850 to 2017. Observed temperatures are shown in black dots. Global warming over the past 150 years was primarily driven by greenhouse gas emissions (red). From Carbon Brief[3]. Britta Voss Postdoctoral Research fellow, U.S. Geological Survey: [This comment comes from a previous review of a similar claim.] Solar forcing is much smaller than CO2 forcing. As this figure from the 2013 IPCC report shows, CO2 radiative forcing (1.68 W/m2) dwarfs solar forcing (0.05 W/m2)[4]. Along with other greenhouse gases, CO2 dominates the total radiative forcing when all positive and negative factors are taken into account. Figure—Radiative forcing estimates in 2011 relative to 1750. Values are global average radiative forcing, partitioned according to the emitted compounds or processes that result in a combination of drivers. Source IPCC AR5[4]."
https://science.feedback.org/review/scientists-observe-most-widespread-bleaching-event-ever-recorded-at-the-great-barrier-reef/,Accurate,"ABC News, Michael Slezak, Penny Timms, 2020-04-06",The Great Barrier Reef is experiencing the most widespread bleaching ever recorded,,"Accurate: For the first time, coral reefs in the northern, central, and southern regions of the Great Barrier Reef were affected by bleaching at the same time. At the time, there is no peer-reviewed study yet to fully document this bleaching event; it should be verified by underwater observations in the coming months.","Increased sea surface temperatures boosted by climate change have triggered five mass bleaching events in the Great Barrier Reef since 1998. In March 2020, scientists conducted aerial surveys and found that all three regions of the Great Barrier Reef were affected by bleaching, making this the most geographically widespread bleaching event observed to date.","The Great Barrier Reef is currently experiencing the most widespread bleaching ever recorded, with 60 per cent of reefs across all three regions affected, according to a detailed survey of the system.",1 – Hughes et al. (2020) We just spent two weeks surveying the Great Barrier Reef. What we saw was an utter tragedy. The Conversation. 2 – Ainsworth et al. (2016) Climate change disables coral bleaching protection on the Great Barrier Reef. Science. 3 – Hughes et al. (2017) Global warming and recurrent mass bleaching of corals. Nature.4 – Hughes et al. (2018) Ecological memory modifies the cumulative impact of recurrent climate extremes. Nature.,"Summary: The claim that “The Great Barrier Reef is experiencing the most widespread bleaching ever recorded” appeared in several media outlets, including an article published by ABC News in April 2020. This claim is based on data collected from aerial surveys conducted in March 2020, which found that 60% of coral reefs across all three regions of the Great Barrier Reef had moderate or severe levels of bleaching[1]. Bleaching occurs when corals expel algae and photosynthetic pigments from their tissues[2]. Although some coral species can recover from light levels of bleaching, severe bleaching can lead to mass mortality of corals[2,3]. Increased sea surface temperatures caused by climate change have triggered five mass bleaching events in the Great Barrier Reef since 1998[3,4]. These events occurred in 1998, 2002, 2016, 2017, and 2020[2,3,4]. In March 2020, Terry Hughes and James Kerry conducted aerial surveys of 1,036 reefs along the Great Barrier Reef in Australia. For the first time, they observed bleaching in the northern, central, and southern regions of the Great Barrier Reef, consistent with the claim that this is the most widespread bleaching event recorded. In addition, “2020 is the second-worst mass bleaching event of the five experienced by the Great Barrier Reef since 1998,” Hughes wrote in The Conversation[1]. About a quarter of the coral reefs the scientists measured were severely bleached, where more than 60% of the corals in each reef were affected by bleaching. The aerial data collected by Hughes will be verified by underwater observations in the coming months. Although this data is currently not peer-reviewed, it does support the claim that this is the most widespread bleaching event recorded in the Great Barrier Reef. Scientists’ Feedback: Terry Hughes Professor, ARC Centre of Excellence for Coral Reef Studies, James Cook University: The claim published by ABC that bleaching in 2020 is more widespread than earlier bleaching events (and second in intensity to 2016) is correct. It comes from the article I wrote in The Conversation on Tuesday, April 6[1]. My article provides three maps that show “For the first time, severe bleaching has struck all three regions of the Great Barrier Reef – the northern, central and now large parts of the southern sectors. The north was the worst affected region in 2016, followed by the centre in 2017.” The maps show unbleached reefs in green, and severely bleached reefs in red. Figure—Surveys of the Great Barrier Reef show the location and severity of bleaching events in 2016, 2017, and 2020. Red circles indicate the most severe bleaching, whereas green circles represent little or no bleaching. Although 2016 was the most severe bleaching event ever recorded, the impacts were primarily in the northern regions. In 2020, severe bleaching was observed across all three regions of the Great Barrier Reef. From The Conversation."
https://science.feedback.org/review/the-antarctic-ozone-layer-is-recovering-but-the-independent-claim-fails-to-grasp-significance-of-study-it-relies-on/,Mostly accurate,"The Independent, Louise Boyle, 2020-03-26",The ozone layer is healing,,"Correct: Scientific studies have shown that the Antarctic ozone is recovering.  Fails to grasp significance of observation: The study the claim is based on analyzed changes in atmospheric circulation patterns influenced by the Antarctic ozone hole, not the recovery of the ozone hole itself. ","The Antarctic ozone layer is healing and has the potential to recover to 1960 levels by the end of the century. Atmospheric circulation trends in the Southern Hemisphere, which are driven by ozone depletion, have also paused or reversed. These changes are attributed, in large part, to reductions in ozone-depleting substances, such as chlorofluorocarbons.","The ozone layer is continuing to heal and has the potential to fully recover, according to a new study","1 – Banerjee et al. (2020) A pause in Southern Hemisphere circulation trends due to the Montreal Protocol. Nature. 2 – Solomon et al. (2016) Emergence of healing in the Antarctic ozone layer. Science. 3 – SPARC/IO3C/GAW (2019) SPARC/IO3C/GAW Report on long-term ozone trends and uncertainties in the stratosphere. I. Petropavlovskikh, S. Godin-Beekmann, D. Hubert, R. Damadeo, B. Hassler, V. Sofieva (Eds.), SPARC Report No. 9, GAW Report No. 241, WCRP-17/2018. 4 – World Meteorological Organization (2018) Executive Summary: Scientific Assessment of Ozone Depletion: 2018. Global Ozone Research and Monitoring Project–Report No. 58. 5 – Morgenstern et al. (2008) The world avoided by the Montreal Protocol. Geophysical Research Letters. 6 – Rigby et al. (2019) Increase in CFC-11 emissions from eastern China based on atmospheric observations. Nature. 7 – Dhomse et al. (2019) Delay in recovery of the Antarctic ozone hole from unexpected CFC-11 emissions. Nature Communications. 8 – Dhomse et al. (2019) Estimates of ozone return dates from Chemistry-Climate Model Initiative simulations. Atmospheric Chemistry and Physics. 9 – World Meteorological Organization (2018) Chapter 3: Update on global ozone: Past, present, and future. Global Ozone Research and Monitoring Project–Report No. 58. 10 – Thompson et al. (2012) The mystery of recent stratospheric temperature trends. Nature. 11 – World Meteorological Organization (2018) Chapter 5: Stratospheric ozone changes and climate. Global Ozone Research and Monitoring Project–Report No. 58. 12 – Thompson & Solomon (2002) Interpretation of recent Southern Hemisphere climate change. Science. 13 – Polvani et al. (2011) Stratospheric ozone depletion: The main driver of twentieth-century atmospheric circulation changes in the Southern Hemisphere. American Meteorological Society. UPDATES: 8 April 2020: This post was updated to include a comment by Antara Banerjee.","Summary: The claim that “The ozone layer is continuing to heal and has the potential to fully recover” appeared in an article published by The Independent in March 2020, and has been shared on Facebook more than 11,000 times. The claim relies on a study recently published in Nature by Banerjee et al.[1]. Previous studies have demonstrated that global total ozone is recovering and has the potential to fully recover by the end of the century[2,3,4], providing support for this claim. However, scientists emphasize that the article misrepresents the focus of the Banerjee paper, as described in their comments below. The claim and study it is based on focus on the Antarctic ozone layer, which has shown patterns of healing in response to reductions in ozone-depleting substances, such as chlorofluorocarbons (CFCs)[1-4]. But rather than showing that the Antarctic ozone is healing, Banerjee et al. (2020) demonstrate that atmospheric circulation trends that were driven by ozone depletion have paused or reversed in the Southern Hemisphere[1]. Scientists’ Feedback: William Seviour Senior Lecturer, University of Exeter: The claim that “the ozone layer is healing and has the potential to fully recover” I believe is accurate. I’ll break this claim into its two parts. First, whether the ozone layer is healing: The focus of the article and paper is on Antarctic ozone, and there have now been some studies suggesting we are starting to see a healing signal there. This is quite tricky to detect because there is a lot of natural variability from year-to-year. Solomon et al. (2016) was probably one of the first[2]. Trends are a bit clearer looking at ozone over the whole globe (not just Antarctica). The SPARC LOTUS report is a good reference here—Fig. 1 of the Executive summary shows increasing ozone trends after 1997 in most places[3]. Figure—Satellite and ground-based records show ozone trends (% change in ozone amount) at different levels in the stratosphere before 1997 (top row) compared to post-2000 (bottom row). Columns represent different latitudes around the world: southern latitudes (left), tropical latitudes (middle), and northern latitudes (right). Note the trends in ozone concentrations are negative pre-1997 (upper panel), but neutral and positive post-2000 (bottom panel). From the SPARC LOTUS report (2019)[3]. Second, the potential to fully recover: The authoritative reference on this subject is the latest (2018) WMO/UNEP Scientific Assessment of Ozone Depletion—e.g. see Figure ES-1 of the Executive Summary[4]. This shows that ozone concentrations (both global and Antarctic) are projected to recover to 1960 levels by the end of this century. Figure—Comparisons of total ozone observations (red points and lines) and chemistry climate models (black lines with grey regions showing uncertainty) for the globe (top) and Antarctic (bottom). Annual global total ozone is averaged over 60°N to 60°S latitudes, whereas Antarctic total ozone is averaged over 60°S to 80°S latitudes. Models project that ozone concentrations will return to levels observed in the 1960s by 2100, assuming future compliance with the Montreal Protocol, which is an international treaty designed to limit ozone-depleting substances, and an increase in greenhouse gas emissions following the RCP-6.0 scenario@. Black lines with arrows indicate the years that ozone abundances are projected to return to values observed in 1980. Adapted from World Meteorological Organization (WMO) Executive Summary: Scientific Assessment of Ozone Depletion (2018)[4]. The evidence linking ozone recovery to reductions in CFCs is very strong, so this claim is accurate. There have been a series of papers, such as Morgenstern et al. (2008), looking at “world avoided” scenarios without the Montreal Protocol and they all show much larger ozone depletion[5]. There has been some recent evidence of violations in the Montreal Protocol with production of a particular CFC (CFC-11) linked to China[6]. Dhomse et al. (2019) has suggested that this violation might delay ozone recovery if it continues[7]. My main criticism of the article is that it largely misses the point of the paper. The paper is not directly about whether the ozone layer is healing, but whether atmospheric circulation changes that have been attributed to ozone depletion are pausing or reversing. Plenty of previous studies (linked above) have looked at recovery of ozone trends, but looking at the circulation trends is new. The fact that the paper shows they are reversing is good news because these changes have been linked to droughts over Australia for instance. I think this Guardian article does a better job at focusing on the winds, not just the ozone. In summary, I think the article is accurate but does not do a very good job of focusing on the results of the paper. Paul Young Lecturer, Lancaster University: The claim that “the ozone layer is healing and has the potential to fully recover” is broadly accurate, backed up by several studies. In general, the best sources of information for those interested in the state of the ozone layer, and the levels and emissions of the synthetic substances that can harm it, are the 4-yearly scientific reports produced under the auspices of the World Meteorological Organisation (WMO) and United Nations Environment Program (UNEP). These reports are written by scientists from all over the world, who assess and review the body of scientific evidence in the peer-reviewed literature. The most recent of these reports was published in 2018[4]. For the specific case of the Antarctic ozone hole, the WMO/UNEP report concluded that there is evidence to show that the hole is beginning to shrink in size, all as a result of the actions of the 1987 Montreal Protocol (and its amendments), which has strong controls on the emissions of halogen-containing ozone depleting substances. However, it is important to note that the ozone hole still continues to appear in southern hemisphere spring every year, and will likely continue to do so beyond the middle of this century (e.g., see Dhomse et al., 2019)[8]. This is because of the long lifetime of many ozone depleting substances in the atmosphere, meaning that they persist even after emissions are essentially zero (e.g. chlorofluorocarbons, CFCs). As the Banerjee et al. Nature paper discusses, the Antarctic ozone hole has also been an important driver of southern hemisphere (SH) climate change, sometimes in a way that is opposite to the effects of the most important human-emitted greenhouse gas, CO2[4]. One of the most important ways in which the ozone hole has impacted SH climate is through pulling the SH jet stream more towards the poles. Among other effects, this has led to a poleward (=southward) trend in rainfall, since the jet stream is basically synonymous with where storms happen. Consistent with the emergence of healing of the ozone hole, their work demonstrates that the ozone hole-driven climate effects are beginning to reverse. In terms of recovery of the world-wide ozone layer, the story is a little more nuanced. As the UNEP/WMO report notes (chapter 3), there is no statistically significant recovery of the total amount of ozone[9]. Detection of recovery is hampered by large, natural year-to-year variability in the atmosphere (“the weather”), which in turn drives large ups and downs in the ozone layer. Nevertheless, one place where the ozone layer is showing clear signs of recovery is the upper stratosphere, which is 35-45km, or ~20-30 miles, up. The recovery here is being driven both by the gradual decreases in ozone depleting substances, but also a slow down in the chemical reactions that destroy ozone. This slowdown is because the upper atmosphere is cooling due to the increases in greenhouse gases (e.g. Thompson et al. (2012); see Box 5-1 of the WMO/UNEP report for an explanation)[10,11]. A. R. Ravi Ravishankara Distinguished Professor, Colorado State University: The findings of the paper are not unexpected since this is what should happen as the ozone hole is starting to heal. The indicators that the ozone hole is showing signs of healing has been known for a few years. This paper shows that the trends in tropospheric circulation due to the ozone hole not getting bigger and showing some healing is detectable. This is great. I want to change the phraseology of the paper. The ozone hole is not really “healing,” it is not getting worse and has stayed just as bad for the past few years as the equivalent effective stratospheric chlorine (EESC) has been nearly constant. I hasten to add that the ozone hole is one indicator of the ozone layer depletion. It is just that the ozone hole is a large signal that is periodic. So, the consequences of its changes are much larger than the global ozone layer depletion starting its course towards its pre-ozone depleting gases state. So, one should expect to detect these changes due to ozone hole changes (but it is really not getting better—just not getting worse!) The Ozone Layer Assessments have clearly indicated that the ozone hole and its “recovery” is least influenced by climate changes. It has also shown that the EESC controls the ozone hole well into the future, unlike the global ozone layer changes that are more influenced by climate change (especially stratospheric cooling and the chemical activity of “climate gases” such as methane and N2O). So, I wonder how circulation changes play out in the future globally. This paper has mixed up the issues between the global ozone layer and the ozone hole. So, I hasten to add that there are no indicators of the changes in tropospheric climate from the global ozone layer depletion or its changes. One should ask what is happening in the Arctic ozone changes (larger depletions than globally but less than the ozone hole) in the Northern winter/spring. That would be nice to know. There has been much written about the “world avoided” by not continuing to increase ODS and the influence of the Montreal Protocol. So, one should also ask what major tropospheric climate changes have been avoided by the Montreal Protocol. I was surprised to not see anything about it. Also, it is important to know that the ozone hole is still pretty large. It is to be expected to continue for decades. The EESC is not changing much. Their Figure 1a shows the small change in EESC. The responses shown in the paper should be viewed as responses due to the absence of continued increases in the ozone hole. I wonder what the circulation changes signals would be when there are sudden stratospheric warmings and hence much smaller ozone holes (i.e., if we focused only on the sudden warming years). Lastly, I want to note that chemically, the ozone hole is not linearly dependent on EESC. That is why it appeared only in the 1980s and one would expect the changes to be small as long as the EESC is still high. Antara Banerjee CIRES Visiting Postdoctoral Fellow, University of Colorado Boulder: Indeed, our study supports this claim. There already exists observational evidence that the actions of the Montreal Protocol in 1987 have led to declines in atmospheric concentrations of ozone-depleting substances (the CFCs). The production and consumption of these substances was banned by the treaty in an effort to prevent further destruction of the ozone layer. This seems to have been effective: there have been signs that the ozone layer is recovering[2,4]. Measurements show that ozone in the upper stratosphere outside of the polar regions has been increasing by 1-3% per decade since around 2000. The Antarctic ozone hole – the most severe example of ozone depletion – has also started to shrink since around 2000, even though the hole is still occurring every year. In the last few decades of the 20th century, there have been some striking changes in the large-scale wind patterns of the Southern Hemisphere during summertime. Notably, the midlatitude jet stream has been shifting towards the South Pole and the tropics have been widening[12]. Antarctic ozone depletion has been shown to be the main driver of these changes[11,13]. The new finding in our paper is that these trends in the Southern Hemisphere circulation have stopped, and might even be reversing, since around the year 2000. Crucially, we use model simulations to attribute this lack of trends to the reduction in ozone-depleting substances due to the Montreal Protocol and the healing of the Antarctic ozone hole. This is therefore yet another sign, this time in the wind patterns, of the effects of the Montreal Protocol. NOTES @: A Representative Concentration Pathway (RCP) is a greenhouse gas concentration trajectory used by the IPCC. RCP-6.0 is an intermediate scenario in which radiative forcing stabilizes at 6.0 W m-2 after 2100."
https://science.feedback.org/review/deforestation-can-facilitate-the-emergence-and-spread-of-some-infectious-diseases/,Mostly accurate,"Now This, Lani Chan, Tom McKenna, 2020-03-20",Deforestation has made humans more vulnerable to pandemics,,"Correct: Scientists have established direct and indirect links between deforestation and the emergence and spread of some infectious diseases.  Misrepresents a complex reality: The effects of deforestation on disease dynamics are complex and multifaceted. Scientists do not fully understand how anthropogenic land use changes, including deforestation, affect human vulnerability to pandemics. ","Deforestation can facilitate the emergence and spread of infectious diseases by creating habitats well suited for disease vectors and increasing connectivity between humans and wildlife. However, the effects of deforestation, and other land use changes, on human vulnerability to pandemics is a complex process that is not entirely understood.","Deforestation has made humans more vulnerable to pandemics. Years of scientific research shows that deforestation has led to a rise in the spread of diseases affecting humans. By reducing the amount of available habitat, species are forced into smaller, shared areas, and brought into closer contact with cities and towns.","1 – Patz et al. (2004) Unhealthy landscapes: Policy recommendations on land use change and infectious disease emergence. Environmental Health Perspectives. 2 – MacDonald and Mordecai (2019) Amazon deforestation drives malaria transmission, and malaria burden reduces forest clearing. PNAS. 3 – Jones et al. (2008) Global trends in emerging infectious diseases. Nature. 4 – Wolfe et al. (2005) Bushmeat hunting, deforestation, and prediction of zoonotic disease. Emerging Infectious Diseases. 5 – Plowright et al. (2015) Ecological dynamics of emerging bat virus spillover. Proceedings of the Royal Society B. 6 – Afelt et al. (2018) Bats, coronaviruses, and deforestation: Toward the emergence of novel infectious diseases? Frontiers in Microbiology. 7 – Weiss & McMichael (2004) Social and environmental risk factors in the emergence of infectious diseases. Nature Medicine. 8 – Epstein (2001) Climate change and emerging infectious diseases. Microbes and Infection. 9 – Patz et al. (1996) Global climate change and emerging infectious diseases. JAMA.","Summary: The claim that “deforestation has made humans more vulnerable to pandemics” appeared in a Facebook video published by NowThis Future in March 2020, receiving more than 140,000 views in the first 10 days after it was posted. Scientific studies have established links between deforestation and the emergence and spread of infectious diseases, providing support for this claim[1,2,3]. However, the effects of deforestation on human vulnerability to pandemics are complex and multifaceted. As a result, scientists do not fully understand this process, as the reviewers describe in their comments below. More than two-thirds of emerging infectious diseases come from wildlife, including HIV, Ebola, and SARS[3]. Deforestation can directly increase the likelihood that a pathogen will be transferred from wildlife species to humans through the creation of suitable habitats for vector species. For example, clearing forest patches in the Brazilian Amazon created moist environments ideal for a mosquito species that is the primary vector of malaria in the region[2]. As described in MacDonald and Mordecai (2019), “Our results suggest [that] a 10% increase in deforestation leads to a 3.3% increase in malaria incidence,” (see the figure below)[2]. Figure—Annual area of forest loss within a given municipality in the Brazilian Amazon increased the incidence of malaria, measured by the number of reported malaria cases by municipality from 2003 to 2015. Adapted from MacDonald and Mordecai (2019)[2].Habitat destruction and fragmentation due to deforestation can also increase the frequency of contact between humans, wildlife species, and the pathogens they carry[1]. This can occur through direct transfer of pathogens from animals to humans or indirectly through cross-species transfer of pathogens from wildlife to domesticated species[1]. By reducing the availability of natural habitats, some wildlife species are driven to find new food resources in urban and suburban areas[4,5]. These patterns are consistent with the claim that “species are forced into smaller, shared areas, and brought into closer contact with cities and towns.” As described in Alfet et al. (2018), “Houses and barns offer shelter for cave-dwelling bats while orchards and fields attract frugivorous bats. This attractive effect of anthropized environments on bats with differing biological needs results in a higher concentration and biodiversity of bat-borne viruses. This increases the risk of transmission of viruses through direct contact, domestic animal infection, or contamination by urine or feces.”[6] The construction of logging roads is another aspect of deforestation that can facilitate the emergence and spread of infectious diseases. Logging roads have been linked to increases in bushmeat consumption as well as travel between rural and urban areas[4]. Wildlife markets for consumption, medicine, trophies, and pets bring many wildlife species together, creating opportunities for disease spillover from animals to humans. As described in a study by Wolfe et al. (2005), “Increasing densities of human populations in urban centers close to bushmeat hunting areas and the increasing rates of movement of people between village, town, and city, will increase R0 [the reproduction number of an infection] and the risk for new epidemic zoonoses”.[4] Increases in human population growth and density drive deforestation, as well as a variety of other land use changes that influence the emergence and spread of infectious diseases, potentially making humans more vulnerable to pandemics[1,3,7]. Although scientists have established some connections between deforestation and infectious diseases, many effects in this complex process remain unresolved. Scientists’ Feedback: Kate JonesProfessor of Ecology & Biodiversity, University College London & David Redding MRC UKRI/Rutherford Fellow, University College London: I don’t think the system is as simple as deforestation causes diseases—it is a pretty complex and not well understood process. Land use change probably does act to change the composition of the species that humans are exposed to—and this may change the transmission dynamics between people and wildlife and cause jumps to be more likely. For example, deforestation for economic activity such as mining and agricultural development can create open sunlight areas with abundant rainfall, the ideal habitat for the main malaria vector in the Amazon region, Anopheles darlingi. We are changing the transmission dynamics between wildlife and people by converting landscapes, developing agriculture, and moving domestic species into areas that we haven’t before, exposing ourselves to new pathogens. Over two thirds of human infectious diseases are originally from animals, including diseases such as HIV, Lassa fever, and Ebola. It is likely that the new coronavirus also spilled over into humans from wildlife, potentially from a live wildlife market, although this is still being investigated. We are also moving wildlife around the world like never before and mixing species in wild animal markets—creating new virus cocktails. Rapid uncontrolled urbanisation combined with international travel and trade is facilitating the emergence and re-emergence of viruses. Jessie Abbate Post-doctoral Research Associate, French Institute of Research for Development: I think everything in this is true. Climate change, including deforestation which drives it, is a key driver of cross-species transmission which is where zoonotic emerging diseases come from[8,9]. The more often this happens, the more chances there are that a pathogen which normally is adapted to its natural animal host but happens to be randomly good at transmitting between humans will do so. READ MORE Several other media outlets have covered the science linking deforestation and wildlife habitat destruction to infectious disease pandemics. A National Geographic article describes how deforestation can facilitate the spread of novel diseases from wildlife species to humans. A recent article in Scientific American discusses how we can use knowledge about the effects of deforestation on infectious diseases to better prepare for viral outbreaks, such as the coronavirus."
https://science.feedback.org/review/global-data-contradict-claim-of-no-acceleration-in-sea-level-rise/,Inaccurate,"Watts Up With That?, Willis Eschenbach, 2020-03-08",The long-term tide gauge datasets are all in agreement that there is no acceleration,,Factually Inaccurate: Quantitative analysis of global data clearly demonstrates that sea level rise has accelerated.  Misrepresents a complex reality: This claim focuses primarily on individual tide gauge stations rather than a global compilation while failing to account for causes of regional variation.,"Peer-reviewed global analyses of both tide gauge and satellite data have demonstrated that sea level rise has, in fact, accelerated in recent decades.","The long-term tide gauge datasets are all in agreement that there is no acceleration, neither in the early nor in the recent parts of the records. Yes, they often porpoise a bit above and a bit below the trend line, but there is no evidence of any CO2-caused recent increase in the rate of sea-level rise. The satellite dataset, on the other hand, is a splice of a selected four of the nine available satellite sea-level datasets. The changes in trend seem to be associated with the splices. Unfortunately, this spliced record is both too short and too fractured to draw any conclusions about acceleration.","1- Woodworth et al. (2010) A Note on the Nodal Tide in Sea Level Records, Journal of Coastal Research 2- Dangendorf et al. (2019) Persistent acceleration in global sea-level rise since the 1960s, Nature Climate Change 3- Kopp et al. (2016) Temperature-driven global sea-level variability in the Common Era, PNAS 4- WCRP Global Sea Level Budget Group (2018) Global sea-level budget 1993–present, Earth System Science Data 5- Dangendorf et al. (2017) Reassessment of 20th Century Global Mean Sea Level Rise,PNAS.","This article on the blog “Watts Up With That?” attempts to show that sea level rise is not accelerating by removing “underlying cycles” in the data that are incorrectly assumed to be tidal cycles. The author smooths a selection of individual coastal sea level records and simply looks for visible acceleration. This fails to account for regional variation in sea level or to measure acceleration with an actual calculation. In fact, a proper quantitative analysis of global data—even after this smoothing process—would clearly show acceleration. The article also claims that satellite sea level data cannot show acceleration because of problems lining up data from different satellites with overlapping mission timeframes. However, the article describes none of the processing procedures that scientists use to correct biases between instruments and instead falsely claims that scientists “simply picked some convenient records from the group above, spliced them together, and called it a valid record fit for all purposes”. In reality, rigorous analysis of satellite data also demonstrates that sea level rise has accelerated. Scientists’ Feedback: Thomas Frederikse Postdoctoral researcher, Jet Propulsion Laboratory/California Institute of Technology: There’s a lot that goes disastrously wrong in this analysis. The idea is to use a variant of EMD (empirical mode decomposition) to remove cycles in sea-level data to find out whether there’s an acceleration in sea level. While EMD and its variants are powerful tools, there’s one big issue: it does not quantify the presence or non-presence of an acceleration. It is just another approach to low-pass filter a data set. Low-pass filtering is basically drawing a smooth curve through a noisy data set. An acceleration, on the other hand, is a well-defined phenomenon. We say that there’s an acceleration when we fit a second-order polynomial (a parabola) to the data and the quadratic coefficient is positive. There are rigorous mathematical tools available to determine the presence or absence of accelerations in sea-level records, which are of course not shown here. The article just shows some smoothed sea-level curves from tide gauges, and it is up to the reader to quantify the presence or non-presence of an acceleration. This of course does not make sense, as we do have good statistical methods to objectively determine this. Then from a purely visual inspection, it’s claimed that because of the multi-decadal cycles in sea-level records—which are falsely attributed to tides (see Woodworth et al.[1] for more details)—we cannot detect an acceleration in the 27-year-long satellite record of sea level. This is a classic and wrong extrapolation. At first, only a few isolated tide-gauge records are discussed. Mainly because of ocean dynamics, local and regional sea level shows large decadal and multi-decadal variations, and therefore it is indeed difficult to find an acceleration in a single tide gauge record. Only European and US tide-gauge records are shown. Because these tide gauges are relatively close to the places where most of the ice melt that has driven sea-level changes since ~1900, they will see much less sea-level rise from ice melt than the global mean due to gravity and solid-Earth effects. Therefore, without explicitly taking this into account, we cannot say anything about global sea levels based on records in Europe and North America alone. When all available tide-gauge records are combined to compute global sea levels, a clear acceleration in sea level since 1900 is visible[2]. Combined with longer proxy records, the data shows that global sea levels have risen at a faster pace than any other century over the last 3,000 years, and that the 21st-century rate of global sea level is already three times as high as the twentieth-century rate[3]. Secondly, the satellite record: Contrary to tide gauges, satellites do cover the global oceans (except some small parts around the poles due to the specific satellite orbits). Regional sea level can show all sorts of decadal fluctuations due to weather and ocean dynamics, which is some sort of redistribution of sea level, but this cancels out on a global scale. Tides, for example, don’t add or remove water from the oceans. Therefore, it’s much easier to detect an acceleration in global sea level. We also track where the extra water is coming from with in-situ floats and satellite gravity observations. These observations tell us remarkably accurately that the acceleration in global sea level is driven by accelerated ice mass losses from Greenland and Antarctica, and due to accelerating thermal expansion because the oceans absorb almost all the excess heat that gets trapped due to the Greenhouse effect (see this paper[4] for all the numbers). Summarizing, we can determine an acceleration in sea level from altimetry and we know what’s causing it. Benjamin Horton Professor, Earth Observatory of Singapore: [This comment is taken from a previous evaluation of a similar claim.] There is so much evidence from satellites, tide gauges, and geological records to show sea-level is rising[5]. For example, from my research, we have shown that the 20th-century rise was extraordinary in the context of the last three millennia—and the rise over the last two decades has been even faster[3]."
https://science.feedback.org/review/global-warming-and-the-covid-19-pandemic-are-unrelated-issues-one-will-not-protect-us-from-the-other-life-site-news/,Flawed reasoning,"LifeSite News, Andrea Widberg, 2020-03-17","If we want to protect ourselves from the coronavirus, we must back away from all the climate change efforts we've been making",,"Flawed reasoning: The article containing this claim fails to acknowledge that disease outbreaks and global warming occur at very different time scales. In addition, it failed to calculate the magnitude of global warming that would be necessary to have a significant effect on the COVID-19 pandemic.  Misrepresents a complex reality: The article containing this claim omits the other factors that actually drive COVID-19 transmission, including the level of existing immunity within a population and population density. ","Some preliminary scientific publications report that SARS-CoV-2 may be less prevalent or less contagious in warm and humid climates. However global warming does not occur at a pace or magnitude that would prevent further SARS-CoV-2 propagation. In addition, scientists emphasize that virus propagation primarily depends on other factors such as existing immunity and there is currently no way to reliably predict the spread of COVID-19 on a warmer Earth.","If we want to protect ourselves from the coronavirus, we must back away from all the climate change efforts we've been making","1 – Wang et al. (2020) High Temperature and High Humidity Reduce the Transmission of COVID-19. SSRN (pre-publication). 2 – Sajadi et al. (2020) Temperature, Humidity and Latitude Analysis to Predict Potential Spread and Seasonality for COVID-19. SSRN (pre-publication). 3 – Li et al. (2019) Global patterns in monthly activity of influenza virus, respiratory syncytial virus, parainfluenza virus, and metapneumovirus: a systematic analysis. The Lancet. 4 – Baker et al. (2019) Epidemic dynamics of respiratory syncytial virus in current and future climates. Nature Communications. 5 – Luo et al. The role of absolute humidity on transmission rates of the COVID-19 outbreak. medRxiv (pre-publication). 6 – Frieden and Lee. (2020) Identifying and Interrupting Superspreading Events—Implications for Control of Severe Acute Respiratory Syndrome Coronavirus 2. Emerging Infectious Diseases. 7 – Wang et al. (2020) Evolving Epidemiology and Impact of Non-pharmaceutical Interventions on the Outbreak of Coronavirus Disease 2019 in Wuhan, China. medRxiv (pre-publication). 8 – Liu et al. (2020) The reproductive number of COVID-19 is higher compared to SARS coronavirus. Journal of Travel Medicine. 9 – Biggerstaff et al. (2014) Estimates of the reproduction number for seasonal, pandemic, and zoonotic influenza: a systematic review of the literature. BMC Infectious Diseases. 10 – Viboud et al. (2006) Influenza in tropical regions. PLoS Medicine. 11 – Bloom-Feshbach et al. (2013) Latitudinal variations in seasonal activity of influenza and respiratory syncytial virus (RSV): a global comparative review. PLoS One. 12 – Li et al. (2019) Global patterns in monthly activity of influenza virus, respiratory syncytial virus, parainfluenza virus, and metapneumovirus: a systematic analysis. The Lancet Global Health. 13 – Tamerius et al. (2011) Global influenza seasonality: reconciling patterns across temperate and tropical regions. Environmental Health Perspectives. 14 – Memish et al. (2020) Middle East respiratory syndrome. The Lancet. 15 – Shaman and Kohn. (2009) Absolute humidity modulates influenza survival, transmission, and seasonality. Proceedings of the National Academy of Sciences. 16 – Hansen et al. (2005) Earth’s energy imbalance: Confirmation and implications. Science. 17 – Van Doremalen et al. (2020) Aerosol and Surface Stability of SARS-CoV-2 as Compared with SARS-CoV-1. New England Journal of Medicine. 18 – Wang et al. (2020) Temperature significant change COVID-19 Transmission in 429 cities. medRxiv (pre-publication).","Summary: An article published on 17 March 2020 on Life Site News claims that “[i]f we want to protect ourselves from the coronavirus, we must back away from all the climate change efforts we’ve been making.” However, scientists who reviewed this claim unanimously reject this conclusion, explaining that global warming and virus seasonality are two phenomena of different time scales so that one cannot be harnessed to control the other. They also point out the paucity of data regarding SARS-CoV-2 transmission. This claim is based on the unpublished findings of several research groups, which recently reported a possible effect of local temperature and humidity on the transmission of SARS-CoV-2, the coronavirus responsible for the current pandemic of COVID-19. A team in China published a preprint article comparing the transmission of SARS-CoV-2 in different Chinese cities, relating it to local temperature and humidity levels[1]. Their overall conclusion was that the virus is transmitted more efficiently in colder and drier environments. Similarly, a study led by researchers from the University of Maryland observed that most SARS-CoV-2 transmission occurs along a latitude corridor where temperatures averaged 5-11°C[2]. Based on these results, the author of the Life Site News article suggested that a warmer Earth would mitigate the transmission of SARS-CoV-2 and that stopping current efforts to limit global warming would be an appropriate response to COVID-19 propagation. Scientists who reviewed this claim unanimously rejected this conclusion, citing flawed reasoning. It is true that certain viruses have a transmission advantage at certain times of the year. Examples of seasonality can be seen with the influenza virus and the respiratory syncytial virus which peak preferentially during colder months in temperate regions[3,4]. Many direct or indirect factors can explain seasonality. For example, UV radiation tends to be more intense during the warmer season, leading to more rapid deterioration of virus particles, while higher humidity may hamper their dissemination in the air, as explained in this news article by Science. However, Prof. Mohammad Sajadi, a virologist at the University of Maryland School of Medicine and first author of one of the research pre-prints mentioned in the Life Site News article[2], specifies that “in tropical and subtropical regions, seasonal respiratory viruses can be present year-round and cause several peaks of infection”. Because the outbreak of COVID-19 is very recent, the data are still scant: “there is a chance that SARS-CoV-2 transmission will be somewhat weakened by summer temperatures if it behaves like the Influenza virus does, but at this point we really do not know enough to say that”, explains Dr. Devin Kirk who investigates the effect of climate change on infectious diseases at Stanford University. While some pre-print studies predict a decline in the rate of spread of COVID-19 in warmer climates, others disagree[5]. And recent outbreaks in tropical countries such as Singapore and Brazil confirm that temperature or humidity alone is not sufficient to prevent COVID-19 epidemics. Consistently, several reviewers emphasized that other factors besides temperature or humidity are actually the dominant drivers of the current pandemic. “At this stage, the fact that there is no population immunity means we will likely see significant spread of the virus, even in warmer climates,” highlights Dr. Rachel Baker, a researcher in epidemiology and environmental studies at Princeton University. Micaela Martinez, an infectious disease specialist at Columbia University, shares this view: “Currently, environmental factors, such as temperature and humidity, will likely be overridden by the fact that so much of the world is susceptible to this infection and can act as kindling to allow this pandemic to grow.“ Therefore, active efforts to mitigate virus propagation that target human behavior and to develop treatments are more likely to offer an effective solution. Even if the virus were less virulent under warmer or more humid conditions, it will still jump from one person to another in cases of close contact, warns Prof. Akiko Iwasaki, an immunobiologist at Yale University: “Even in warm and humid conditions, people should still wash hands and practice social distancing measures. If someone sneezes close to you, no amount of temperature and humidity can prevent droplet spray containing the virus from coming into contact with your face.” The scientists who reviewed this claim also unanimously rejected the idea that allowing global warming to intensify may be a valid response to the COVID-19 pandemic. Global warming occurs at a completely different pace than the progression of epidemics. Current average global temperatures are 1°C higher relative to the early 20th century. This rise in Earth’s average temperature would therefore have no impact on disease epidemics “because there are significant lag times in the climate’s response to human behavior. Were we to cease climate change mitigation efforts now, the effects would only be felt 40 years down the line,” Dr. Baker says. Finally, based on available data, there is inconsistency between the magnitude of global warming and the rise in temperature that would be required to stop SARS-CoV-2 transmission. One of the studies that the Life Site News article is based on reports that a 1°C increase in ambient temperature correlates with a 0.0383 decrease in the SARS-CoV-2 reproduction number (R0)@[1]. Recent reports suggest an initial average reproduction number of 2.8 to 3.8[6,7,8], while a meta-analysis indicates that the reproduction number of seasonal influenza is around 1.28[9]. Based on the same premises and publications referenced in the Life Site News article, and assuming a linear correlation, a staggering increase of between 39°C and 66°C would be required to reduce SARS-CoV-2 propagation down to the level of the seasonal flu if one were to solely rely on temperature. At this point, the Earth would be entirely uninhabitable to humans. In conclusion, there is no basis whatsoever to claim that “backing away from climate change efforts” would help “protect ourselves from the coronavirus”. Scientists’ Feedback: Micaela MartinezAssistantProfessor, Mailman School of Public Health, Columbia University: In my expert opinion, as a specialist on infectious diseases seasonality and also a professor in climate change and human health, I can say that the logic behind this statement is inaccurate because: It is wrongly assuming that long-term changes in global surface temperature (i.e., climate change) are equivalent to changes in the weather seasonally. It is the weather (which operates on a shorter time scale) that is important to consider when evaluating transmission of coronavirus. We are still very early on in this pandemic and it will take multiple seasons (i.e., years) to properly evaluate how weather conditions may influence transmission. Currently, environmental factors, such as temperature and humidity, will likely be overridden by the fact that so much of the world is susceptible to this infection and can act as kindling to allow this pandemic to grow. Mohammad Sajadi Associate Professor , University of Maryland School of Medicine: Those seeking to roll back climate change efforts in part because of our findings of the potential seasonality of the SARS-CoV-2 neither understand climate science nor virology. Seasonal viruses have the potential to significantly affect every part of the planet, but at different times[10,11,12,13]. In the Arabian Peninsula, MERS was unable to have significant community transmission (majority of outbreaks were in the hospital)[14]. The solution is not for everyone to go and live in a desert environment, or create a planet that is inhospitable to countless forms of life. I believe we can find a more efficient solution to this problem than ruining the planet for future generations. [It] is our prediction, based on what we have seen thus far, [that regions with warmer/more humid climate will see less COVID-19 than colder/drier regions]. However, in tropical and subtropical regions, seasonal respiratory viruses can be present year round, and cause several peaks of infection, so a more accurate picture would be to do a yearly tally and comparison of the areas. From what I have read, with global warming, different areas will be affected differently. If the R0 [the basic reproduction number]@ will change with different temperatures as we hypothesize (and shown by a different group), then changes in the temperatures/humidity could increase risk for certain areas and decrease those for others. Rachel Baker Postdoctoral Research Associate, Princeton Environmental Institute: There appear to be two main themes in the article. One suggesting that if the virus is sensitive to temperature, we should abandon efforts to mitigate climate change. The second, suggesting some individual actions to promote sustainability such as reusable bags, straws, or taking public transport should be altered to lower individual risk. To address the first theme: we currently have only a limited understanding of the virus’s link with climate drivers. However, other coronaviruses as well as influenza and RSV (respiratory syncytial virus) all exhibit seasonal cycles that appear to be climate-driven[4,15]. It may well be that the virus is sensitive to warmer temperatures. However, there are several other factors that also affect transmission. Most importantly, at this stage, the fact that there is no population immunity means we will likely see significant spread of the virus even in warmer climates. Furthermore, because there are significant lag times in the climate’s response to human behavior, were we to cease climate change mitigation efforts now the effects would only be felt 40 years down the line[16] — not the most practical option for helping limit the current pandemic. To address the second theme: the virus has been shown to survive for hours to days, depending on the surface[17]. While there have been no specific studies on plastic bags versus cloth bags, my guess is carrying your own bag is less risky than touching a plastic bag that may have been sitting out in the store for days, with similar logic applying to straws. Of course, during this phase of the pandemic, individual changes to behavior are required to reduce disease transmission, including minimizing travel. Devin Kirk Postdoctoral Scholar, Stanford University: The author of [this claim] argues throughout the article that “if we want to protect ourselves from the coronavirus, we must back away from all the climate change efforts we’ve been making.” There are several inaccuracies and illogical arguments throughout this article. First, I’ll cover the foundation of their argument: the link between temperature and SARS-CoV-2 transmission. They use three different manuscripts to support their point that SARS-CoV-2 is negatively affected by warming temperatures. None of these three manuscripts are peer-reviewed, and each has what I would consider significant flaws that makes me doubt their conclusions. A couple notes on the different papers: Wang, J. et al.[1] Their country-level analyses use number of cases, even though that is likely to depend more on timing since introduction or number of tests being run than climate. To determine the effects of summer weather on COVID-19 transmission, they are extrapolating far beyond their data to July temperatures. The pattern between temperature and transmission in Chinese cities here could easily be unimodal rather than the linear model they fit. Sajadi, M. et al.[2] They claim that [COVID-19] is establishing in the 30-50 degree north corridor at similar weather patterns (5-11°C), and that there is a lack of establishment based on where there is travel and we should expect it. However, Scandinavia is getting cases and is out of this weather range, Mexico is out of this range and likely doesn’t have cases due to limited testing (according to the head of internal medicine at the ABC Medical Center in Mexico City), Australia is growing, Southeast Asia is growing now, Toronto isn’t in the weather range. Wang, M. et al.[18] Epidemiological data and their R0 proxy are relatively limited, especially spatially. Weather data (using just the capital of a province) is limited. It does not appear they are controlling for factors like population size. In summary, none of the three pre-print manuscripts the author relies on to link transmission to temperature are peer-reviewed and each has flaws in my opinion. There is a chance that SARS-CoV-2 transmission will be somewhat weakened by summer temperatures if it behaves like the Influenza virus does, but at this point we really do not know enough to say that. Moreover, this (also not yet peer-reviewed) pre-print analyzes data and finds that changes in temperature “will not necessarily lead to declines in COVID-19 case counts”[5]. At this point, there aren’t peer-reviewed papers regarding temperature’s effects on SARS-CoV-2, and we probably won’t know if it has an effect until temperatures really start to warm. I think the best explainer about what we do or do not know about temperature’s effects on SARS-CoV-2 is found in this blog post by Marc Lipsitch, the director of the Center for Communicable Disease Dynamics at Harvard. Marc Lipsitch is easily one of the global leaders in the field, so in my opinion that blog post carries a lot of weight. He concludes that seasonality will probably not lead the disease to go away on its own. Finally, I just want to note the pretty ridiculous logical argument that if higher temperatures harm SARS-CoV-2 transmission (which, as I explain above, we do not know yet), this means that climate change is good for us to protect from the disease. This is a bad argument because climate change operates over a relatively very long time scale compared to the speed of this pandemic. Even if extremely high temperatures decreased viral transmission, we may need over a hundred years of global warming to get to those kinds of temperatures. It simply doesn’t make sense. Akiko Iwasaki Professor, Yale School of Medicine: The claim that we should promote global warming to counter coronavirus is absurd. Global warming happens very slowly: 0.86°C increase [from] 1880 – 2012. Even if we did everything possible to increase global temperature fast, this will have dire consequences on Earth without having any impact on COVID-19 spread. While high temperature and humidity will likely reduce airborne transmission rate, the virus will still spread through direct contact or through contaminated surfaces. Even in warm and humid conditions, people should still wash hands and practice social distancing measures. If someone sneezes close to you, no amount of temperature and humidity can prevent droplet spray containing the virus from coming into contact with your face. Jeffrey Shaman Professor, Mailman School of Public Health, Columbia University: There’s no basis for that assertion. Halting global warming will not stop the spread of this virus. Sounds like an effort to advance an anti-climate change agenda. NOTES @: The reproduction number R0 describes how many individuals a contagious person will infect. For instance, a R0 of 2 means that each person will on average infect two other individuals. The reproduction number is not a constant as it highly depends on the epidemiological and environmental context. READ MORE Full Fact also fact-checked similar claims that warmer weather will stop the outbreak of the novel coronavirus, explaining that “even if it ultimately turns out to be a seasonal virus, it is unlikely to behave like similar viruses in the short term. This is because it is so new that very few people are immune from it.” Health Feedback has produced a number of other claim reviews on COVID-19. You can view them here."
https://science.feedback.org/review/temperature-trends-in-the-u-s-are-consistent-with-warming-around-the-world-contrary-to-electroverse-claim-cap-allon/,Flawed reasoning,"Electroverse, Cap Allon, 2020-01-22",Historical data of temperature in the U.S. destroys global warming myth,,Flawed reasoning: The U.S. occupies a very small percentage of the world. Global warming trends cannot be determined based on local daily temperature records in a small number of locations. ,"Land surface, sea surface, and atmospheric temperature data all show trends of global warming. The warming trend observed over the past century is correlated with increased levels of CO2.  ","Historical data destroys the global warming myth, and people are waking to it. According to NOAA’s own historical data, of the 50 U.S. state all-time record high temperatures, 23 were set during the 1930s, while 36 occurred prior to 1960 — climate change proponents are feeding us a fairy tale, and I’m sick of it.",1- Santer et al (2017) Tropospheric warming over the past two decades. Scientific Reports. 2- Hausfather et al. (2017) Assessing recent warming using instrumentally homogeneous sea surface temperature records. Science Advances. 3- Neukom et al. (2019) No evidence for globally coherent warm and cold periods over the preindustrial Common Era. Nature. 4- King (2017). Attributing Changing Rates of Temperature Record Breaking to Anthropogenic Influences. Earth’s Future. 5- Donat et al. (2016). Extraordinary heat during the 1930s US Dust Bowl and associated large-scale conditions. Climate Dynamics. 6- Feldman et al (2015) Observational determination of surface radiative forcing by CO2 from 2000 to 2010. Nature.,"Summary: The claim that historical temperature data in the U.S. “destroy the global warming myth” appeared in an article published by Electroverse in January 2020, receiving almost 1,500 shares on Facebook since then. By focusing solely on maximum daily temperature records in one small region of the world, the claim uses flawed reasoning to argue that global warming is a myth. Even if the U.S. showed steady or cooling temperature trends, this would not prove that global warming isn’t happening given warming elsewhere. Scientific studies have demonstrated consistent warming trends around the world (see the figures below)[1,2]. As described in Neukom et al. (2019), “the warmest period of the past two millennia occurred during the twentieth century for more than 98 percent of the globe.”[3] Figure—Global temperature anomaly data relative to the 20th century average temperature from the Global Historical Climatology Network-Monthly data set and International Comprehensive Ocean-Atmosphere Data Set. These data sets show consistent global warming trends. From NOAA. Historical data from NOAA clearly shows a warming trend in the U.S. as well from January 1895 to December 2019 (see the figure below). Figure—Monitoring networks of temperature anomalies relative to baseline temperatures in the contiguous U.S. (USCRN, ClimDiv, USHCN) from January 1895 to December 2019 show consistent warming trends. From NOAA. The global warming trends in the U.S. are “noisier” than the global data set, primarily because the U.S. only occupies ~2 percent of the world and regional, natural oscillations in temperature are more apparent. Although the specific claim that “of the 50 U.S. state all-time record high temperatures, 23 were set during the 1930s, while 36 occurred prior to 1960” is consistent with NOAA data, this data does not follow maximum temperature trends observed in other regions around the world. King (2017) describes, “Many heat records in the central U.S. still date from the 1930s Dust Bowl period when unusual atmospheric flow and very dry spring periods allowed severe heat extremes to develop (Donat et al., 2016), but in most other parts of the world, current temperature records date from the last few decades.”[4,5] Furthermore, local daily temperature records are not suitable measurements for assessing global warming trends. This claim relies on maximum temperature records collected at a single station in each state. Temperature data from a single station can be influenced by several factors, including time of day the measurement was taken, the angle of the sun, and instrument variation, as Victor Venema explains in the comments below. Lastly, maximum temperature records do not necessarily reflect the warmest years on record nor the average number of warmest days for each state. For example, although the 1930s were relatively warmer than the 1920s and 1960s, it was not warmer than the past two decades. In conclusion, the fact that some local daily heat records were set in the 1930s can not be used as evidence that a warming trend is not happening at the global scale. Scientists’ Feedback: Victor Venema Scientist, University of Bonn, Germany: The post does not support the erroneous claim that historical data destroys the global warming myth. It did not even look at global warming, in other words it did not look whether the global mean temperature shows a long-term increase. The post looked at station data in America, which only covers about 2% of the Earth. Global warming is about the globe. America is known for the Dust Bowl in the 1930, which produced many heat records. While we also expect heat waves to increase, the relationship between the average temperature and record temperatures is complicated, if records would not increase that would not invalidate the increase in the mean. That would require study of the mean temperature. The post did not look at the mean temperature, but at the maximum temperature. Also the minimum temperature shows many record cold temperatures in the first half of the period, which the post conveniently did not mention. Records are rare and hard to measure. For that reason alone they are more spread out over the measurement period and show a less clear trend than the mean temperature. The post looked at raw data, which is not well suited to study warming. For example modern automatic weather stations measure a somewhat smaller temperature than traditional Cotton Region Shelters. You can see this by making side by side measurements with both instruments. In as far as this difference is due to the sun influencing the temperature observations it will be larger for summer temperatures, for the maximum temperature and especially for heat waves and droughts. Global warming is about actual warming, not about changes in the instrumentation. It is just a post on the internet, not a scientific study. In a scientific study the authors would have had to describe exactly what they did. It is not even clear what a record in a certain US state means in this post. Is this one station in a state having a record or the average temperature over the state having a record? For all of the above reasons the claim about global warming does not fit to the presented evidence and would never hold up in the scientific literature, which the authors bypass to directly deceive their readers most of whom will not be aware of the above problems. Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: [Comment from a previous evaluation of a similar claim.] Global temperature datasets, developed by a number of independent research groups, show robust warming in the troposphere and at the Earth’s surface. The radiative effect of carbon dioxide has also been observed[6]. Considering multiple lines of evidence, the IPCC concluded that it is “extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century.” More recent analysis of satellite data shows that tropospheric warming from the satellite record is pronounced and cannot be explained by natural climate variability alone[1]. [Comment from a previous evaluation of a similar claim.] World temperatures measurements began in the 1800s and show a warming burst since the 1970s. Last year we checked with satellite scans of the ocean, confirming the accuracy of the surface measurements[2]. Global warming is a measured fact."
https://science.feedback.org/review/co2-can-increase-plant-growth-in-greenhouses-while-also-negatively-affecting-ecosystems-and-human-societies-mike-adams-natural-news/,Flawed reasoning,"Natural News, Mike Adams, 2013-06-22","CO2 is a plant nutrient...it’s not a pollutant that threatens human civilization. If CO2 was so terrible for the planet, then installing a CO2 generator in a greenhouse would kill the plants.",,"Flawed reasoning: CO2 can increase plant growth in a greenhouse, but the argument that CO2 is not harmful to the planet because plants don’t die is flawed. To assess the overall impact of CO2 emissions on “human civilization”, effects on ecosystems and human societies should also be taken into account. Misleading: Plants require CO2, water, and other nutrients to grow. Although CO2 emissions can increase plant growth in some regions, they also increase heat stress, water stress, and pest prevalence. ","CO2 can increase plant growth but its effects, which decrease with higher concentrations, are limited by the availability of other plant nutrients, such as nitrogen and phosphorus. CO2 emissions can negatively impact natural ecosystems through global warming—e.g. by increasing evaporation and drying up soils in some regions or increasing heavy precipitation in others.","CO2 is a plant nutrient...it’s not a pollutant that threatens human civilization as has been ridiculously claimed by global warming doomsday pushers. CO2 actually increases plant yields, accelerates ""re-greening"" and improves reforestation of the planet. If CO2 was so terrible for the planet, then installing a CO2 generator in a greenhouse would kill the plants.","1- Zhu et al. (2016) Greening of the Earth and its drivers. Nature Climate Change. 2- Mbow et al. (2019) IP Food Security. In: Climate Change and Land: an IPCC special report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems. IPCC report. 3- Rosenzweig et al. (2014). Assessing agricultural risks of climate change in the 21st century in a global gridded crop model intercomparison. PNAS. 4- Moore et al. (2017) New science of climate change impacts on agriculture implies higher social cost of carbon. Nature. 5- Zhang et al. (2014) Nitrogen and phosphorous limitations significantly reduce future allowable CO2 emissions, Geophysical Research Letters. 6- De Graaff et al. (2006) Interactions between plant growth and soil nutrient cycling under elevated CO2: a meta-analysis. Global Change Biology. 7- Shakun et al. (2012) Global warming preceded by increasing carbon dioxide concentrations during the last deglaciation. Nature. 8- Tubiello et al. (2007). Crop and pasture response to climate change. PNAS.","Summary: The claim that CO2 is a plant nutrient and not a pollutant appeared in an article published by Natural News in June 2013, and has gone viral in 2020 with over 1.6 million shares on Facebook over the past three months. This claim uses flawed reasoning to argue that elevated levels of CO2 are not bad for the planet because it doesn’t kill plants in a greenhouse. Although CO2 can increase plant growth in a greenhouse, this effect does not necessarily apply to more complex natural environments where the benefits of CO2 can be outweighed by nutrient limitation and negative climate impacts, such as increasing water stress, heat stress, and the prevalence of pests and pathogens. In order to assess the overall impact of CO2 on the planet, all known effects of CO2 on land ecosystems and human societies should be evaluated, instead of focusing on just one aspect as this claim does[1,2,3,4]. Vegetation has absorbed some of the CO2 emitted by human activities and converted it into leaf biomass, particularly in southeast North America, the northern Amazon, Europe, Central Africa, and Southeast Asia, as seen in the figure below[1]. Figure- Increased CO2 emissions have increased plant growth (leaf area index (LAI)) around the world. From Zhu et al. (2016)[1]. But in addition to CO2, plants require water and other nutrients to grow. Scientific studies show the effects of CO2 on plant growth depend on the availability of other nutrients, such as phosphorus and nitrogen, as seen in the figure below[2,5,6]. Figure- Under high concentrations of CO2 (RCP8.5), crop models (GGCMs) predict that nitrogen (N) stress will reduce crop yields (%) in 2070-2099 relative to yields from 1980 to 2010. From Mbow et al. (2019)[2]. CO2 emissions are also predicted to produce less nutritional crops and reduce crop yields over time[2]. “While increased CO2 is projected to be beneficial for crop productivity at lower temperature increases, it is projected to lower nutritional quality,” according to the IPCC report on food security[2]. Because CO2 emissions contribute to global warming, crop yields are predicted to decline with increasing temperatures due to increases in heat stress, water stress, and the persistence of pests and pathogens, as seen in the figure below[3,4]. Figure- A meta-analysis of 56 studies predicts that crop yields for maize, rice, wheat, and soy decline as temperatures increase relative to local baseline growing-season temperatures. From Moore et al. (2017)[4]. More broadly, increases in plant growth due to increased CO2 emissions may be offset by negative effects on land ecosystems due to rising global temperatures, prolonged droughts, and increases in intense rainstorms[2,6]. In tropical and semi-arid regions, even moderate increases in temperature could lead to drier conditions that induce water stress, disrupt plant reproduction, and reduce crop yields[7]. Nitrogen stress due to soil degradation is predicted to result in even greater declines in crop yields in the tropics[2]. Additionally, the effects of climate change are not limited to terrestrial plant productivity. Impacts on weather extremes, coastal infrastructure, human health, and marine ecosystems—among other things—are also relevant to the question of whether CO2 is a “pollutant that threatens human civilization”, in the article’s words. Scientists’ Feedback: Pierre Friedlingstein Professor, University of Exeter: [Comment from a previous evaluation of a similar claim.] This is the usual misleading argument that if CO2 is good for plants, it cannot be bad for the climate. CO2 is needed for plant growth (along with water, nutrients, and energy from the sun)—but it does not change the fact that CO2 is a greenhouse gas. It increases the radiative forcing of the planet and leads to warming, as observed over the last century[6]. Frances Moore Assistant Professor, University of California Davis: [Comment from a previous evaluation of a similar claim.] In a meta-analysis of over 1,000 studies of the effects of climate change on agriculture, we find that, while CO2 is beneficial for crops, this effect rapidly decreases with increasing concentrations[4]. The net effects of climate change on agriculture, including both the benefits of CO2 fertilization and the negative effects of warming, is negative for almost all regions. The effects of CO2 emissions on agriculture cost approximately $8.5 per ton, even accounting for the positive effects of CO2 fertilization. Sara Vicca Postdoctoral research fellow, University of Antwerp: [Comment from a previous evaluation of a similar claim.] Plants don’t only need CO2 and water, but also nutrients like nitrogen and phosphorus. If the latter are not sufficiently available, plants may not respond to elevated CO2 at all[5,6]. Moreover, climatic changes (and particularly extreme events) are an important threat to ecosystems and to the land carbon sink[2,3,7,8]. Alexis Berg Research Associate, Harvard University: [Comment from a previous evaluation of a similar claim.] Yes, we are seeing an increase in vegetation around the world, with satellites showing up to 50% of the land surface greening over the last 30 years, most of it being indeed attributed to increased atmospheric CO2[1]. This is not a surprise. This vegetation increase is consistent with the fact that we know that about a quarter of our CO2 emissions is being taken up by the land biosphere (another quarter going into the oceans, and the remainder staying in the atmosphere). This greening is taken into account in climate models. The real question is how long this greening is going to go on (there are already indications that it is slowing down), as we expect that as climate warms further, adverse impacts on ecosystems may start to offset the positive impact of increased atmospheric CO2—particularly in places where regional climate is moving away from the “comfort zone” of current ecosystems. Amber Kerr Researcher, Agricultural Sustainability Institute, University of California, Davis: [Comment from a previous evaluation of a similar claim.] CO2 is not a pollutant in the sense of being acutely toxic to life, but this framing is highly misleading. Water is also non-toxic and essential to life on Earth, but too much water in the wrong places can be devastating."
https://science.feedback.org/review/electroverse-article-incorrectly-claims-the-sun-is-behind-climate-change/,Incorrect,"Electroverse, Roger Higgs, 2020-03-11","the IPCC is wrong − the sun, not CO2, drove modern global warming",,"Misleading: Many things the article claims climate scientists ""assume"" are actually conclusions supported by extensive research and evidence. This includes the role of CO2 and other greenhouse gases in driving global warming. Inadequate Support: The article's claims are not supported by published research. Of the two papers cited in the article, one does not support the article's claim and the other was criticized by scientists for errors in its methods.","This article presents a long list of inaccurate claims, but focuses on the idea that the Sun—rather than human-caused greenhouse gas emissions—is responsible for global warming. The available evidence and research clearly shows that this claim is incorrect. Measured patterns of warming, and monitoring of incoming solar energy, rule out the Sun as the source of warming.","the IPCC is wrong − the sun, not CO2, drove modern global warming",,"The article mentions cosmic rays, claiming that changes in cosmic ray nucleation of clouds (via solar magnetic activity) can explain global warming. The effect of cosmic rays has been studied extensively1,2, leading to the conclusion that cosmic rays have not correlated with global cloud cover or temperature. Pierce and Adams conclude that: “changes in cloud condensation nuclei from changes in cosmic rays during a solar cycle are two orders of magnitude too small to account for the observed changes in cloud properties; consequently, we conclude that the hypothesized effect is too small to play a significant role in current climate change”1, While Agee et al conclude: “the observational results presented, showing several years of disconnect between Galactic Cosmic Rays and lower-troposphere global cloudiness, add additional concern to the cosmic ray–cloud connection hypothesis.” An experiment at CERN that directly tested the ability of cosmic rays to nucleate cloud droplets found that “variations in cosmic ray intensity do not appreciably affect climate through nucleation in the present-day atmosphere.”3 The 2013 IPCC report summarized research on this topic when it stated, “Cosmic rays enhance new particle formation in the free troposphere, but the effect on the concentration of cloud condensation nuclei is too weak to have any detectable climatic influence during a solar cycle or over the last century.”4 The scientists’ comments below explain that besides this cosmic ray hypothesis, the solar radiative forcing fluctuations are also insufficient to explain climate changes over the past decades—in contrast to the radiative forcing due to the increased greenhouse gases released by human activities, which matches the magnitude of the observed warming. 1- Pierce and Adams (2009) Can cosmic rays affect cloud condensation nuclei by altering new particle formation rates?, Geophysical Research Letters 2- Agee et al (2011) Relationship of Lower-Troposphere Cloud Cover and Cosmic Rays: An Updated Perspective, Journal of Climate 3- Dunne et al (2016) Global atmospheric particle formation from CERN CLOUD measurements, Science 4- IPCC (2013) Chapter 7, Climate Change 2013: The Physical Science Basis Patrick Brown Assistant Professor, San Jose State University: [This comment comes from a previous review of a similar claim.] Careful analysis that attempts to take into account all major factors and their evolution in time indicates that anthropogenic increases in greenhouse gasses account for more than 100% of the observed warming on the century timescale (requiring cancellation from cooling influences). See the summary graphic from Carbon Brief, below. Source: Carbon Brief Britta Voss Postdoctoral Research fellow, U.S. Geological Survey: [This comment comes from a previous review of a similar claim.] Solar forcing is much smaller than CO2 forcing. As this figure from the latest IPCC report shows, CO2 radiative forcing (1.68 W/m2) dwarfs solar forcing (0.05 W/m2). Along with other greenhouse gases, CO2 dominates the total radiative forcing when all positive and negative factors are taken into account. Figure – Radiative forcing estimates in 2011 relative to 1750. Values are global average radiative forcing, partitioned according to the emitted compounds or processes that result in a combination of drivers. Source IPCC AR5 Timothy Osborn Professor, University of East Anglia, and Director of Research, Climatic Research Unit: [This comment comes from a previous review of a similar claim.] There is strong evidence that solar forcing cannot explain much of the observed warming at all. The “fingerprint” of solar forcing does not match the observed changes at all, neither over time nor space. Solar forcing would warm both the stratosphere and the surface of the Earth, whereas CO2 warms the surface (and the troposphere) but cools the stratosphere. Using radiosondes and (more recently) satellites, we have observed a warming surface and troposphere together with a cooling stratosphere. See Santer et al (2013)* for one of many studies providing this evidence. Figure –Zonal-mean atmospheric temperature trends in satellite observations from January 1979 to December 2012 showing warming of the lower atmosphere (troposphere) and cooling of the upper-atmosphere (stratosphere), from Santer et al (2013)* Santer et al (2013) Human and natural influences on the changing thermal structure of the atmosphere, PNAS Baird Langenbrunner Associate Editor, Nature Climate Change: [This comment is taken from an earlier review of a similar claim.] First, greenhouse gases are well studied, and their properties are nonnegotiable: They absorb and re-emit longwave radiation, whether they’re in a laboratory setting or in the real atmosphere. To back this up with historical evidence, scientists have known since the 1860s that CO2 is a greenhouse gas and since the 1890s that this will affect the heat budget of the Earth through warming. Even then, these claims were based on empirical evidence, and they’re supported by decades of laboratory research. Second, the link between increased greenhouse gas concentrations and warming continues to be supported by research in the last two decades. One study from 2001[1]used satellites to measure the type of energy entering and exiting Earth’s atmosphere and concluded that increases in greenhouse gases were responsible for extra heat measured between 1970 and 1997. The authors state that their results “provide direct experimental evidence for a significant increase in the Earth’s greenhouse effect that is consistent with concerns over radiative forcing of climate.” (Here, the term “radiative forcing” refers to the extra energy trapped in the atmosphere by greenhouse gases, cause warming.) A more recent study[2]arrived at similar conclusions, confirming predictions of the greenhouse effect in Earth’s atmosphere and providing “empirical evidence of how rising CO2 levels … are affecting the surface energy balance.” In other words, rising CO2 was linked directly to warming, even when things like plant uptake of CO2 were considered. 1 – Harries et al (2001) Increases in greenhouse forcing inferred from the outgoing longwave radiation spectra of the Earth in 1970 and 1997, Nature 2 – Feldman et al (2015)Observational determination of surface radiative forcing by CO2 from 2000 to 2010, Nature Mark Richardson Research Associate, Colorado State University/NASA JPL: [This comment is taken from an earlier review of a similar claim.] [These] comments would have been fair in 1896 when Svante Arrhenius calculated that we could cause serious global warming[1]. World temperatures measurements began in the 1800s and show a warming burst since the 1970s. Last year we checked with satellite scans of the ocean[2], confirming the accuracy of the surface measurements. Global warming is measured fact. Working out the culprits has been like Crime Scene Investigation: Physics Edition. Some evidence comes from a facility in Billings, Oklahoma. Parts of air like water vapour and carbon dioxide naturally glow with infrared heat at very specific frequencies. The Billings site has a device that measured an incredibly precise “fingerprint” of the sky’s heating. Investigators reported in 2015[3] that they found fingerprints across the sky with a clear match on the heating trigger. Below the blue line is the file fingerprint for carbon dioxide (CO2) heating, which we release into the air when we do things like burn coal & oil. This file fingerprint comes from basic physics backed by precise lab readings. The red line is the measured fingerprint in the sky over Billings and is a rock solid match. Each spike is extra heat coming down from the extra CO2 molecules that is heating us up. Measurements in Alaska and from satellites[4]confirm this. This is just one slide in the huge folder of empirical evidence showing human activity to be the main cause of recent warming. 1 – Arrhenius (1896)On the Influence of Carbonic Acid in the Air upon the Temperature of the Ground,Philosophical Magazine and Journal of Science 2 – Hausfather et al (2017)Assessing recent warming using instrumentally homogeneous sea surface temperature records, Science Advances 3 – Feldman et al (2015)Observational determination of surface radiative forcing by CO2 from 2000 to 2010, Nature 4 – Harries et al (2001) Increases in greenhouse forcing inferred from the outgoing longwave radiation spectra of the Earth in 1970 and 1997, Nature"
https://science.feedback.org/review/sea-levels-rose-faster-in-the-past-century-than-in-previous-time-periods/,Inaccurate,"American Thinker, Thomas Lifson, 2020-03-07","Sea level rise has been slow and a constant, pre-dating industrialization",,Factually inaccurate: Scientific studies clearly show that rates of sea level rise have increased since industrialization. Misrepresents source: The article incorrectly describes results from a scientific paper published in Geophysical Research Letters (according to an author of that paper) to support its claim that sea level rise is slow and not caused by human factors.,"Sea levels have risen at increased pace since industrialization, with the fastest rates of sea level rise occurring in the late 20th century. At local geographic regions, sea levels can rise faster or slower than the global average, and in the past, these local variations might have been large in magnitude. However, at the global scale, sea levels are rising at an accelerated rate due to human-induced global warming.","Sea level rise has been slow and a constant, pre-dating industrialization ... A study by the University of York found evidence for a period of enhanced pre-industrial sea-level rise of about 2-3 millimetres per year in three locations — Nova Scotia, Maine and Connecticut, which were largely natural, without any human constructions or man-made factors.","1- Kemp et al. (2011) Climate related sea-level variations over the past two millennia. PNAS. 2- Gehrels et al. (2020) A Preindustrial Sea‐Level Rise Hotspot Along the Atlantic Coast of North America. Geophysical Research Letters. 3- Kopp et al. (2016) Temperature-driven global sea-level variability in the Common Era. PNAS. 4- Slangen et al. (2016) Anthropogenic forcing dominates global mean sea-level rise since 1970. Nature Climate Change 5- Dangendorf et al. (2015) Detecting anthropogenic footprints in sea level rise. Nature Communications. 6- Gehrels and Long (2008) Sea level is not level. Geography. 7- Chen et al. (2009) Accelerated Antarctic ice loss from satellite gravity measurements. Nature Geoscience. 8- Meyssignac and Cazenave (2012) Sea level: a review of present-day and recent-past changes and variability. Journal of Geodynamics. 9- Kjeldsen et al. (2015) Spatial and temporal distribution of mass loss from the Greenland Ice Sheet since AD 1900. Nature. 10- Shepherd et al. (2018) Mass balance of the Antarctic Ice Sheet from 1992 to 2017. Nature. 11- Church and White (2006) A 20th century acceleration in global sea‐level rise. Geophysical Research Letters. 12- Jevrejeva et al. (2014) Trends and acceleration in global and regional sea levels since 1807. Global and Planetary Change. 13- Watson et al. (2009) Unabated global mean sea-level rise over the satellite altimeter era. Nature Climate Change. 14- Nerem et al. (2018) Climate-change–driven accelerated sea-level rise detected in the altimeter era. PNAS. 15- Kemp et al. (2009). Timing and magnitude of recent accelerated sea-level rise (North Carolina, United States). Geology. 16- Woodworth et al. (2009) Evidence for the accelerations of sea level on multi‐decade and century timescales. International Journal of Climatology 17- Church and White (2011). Sea-level rise from the late 19th to the early 21st century. Surveys in Geophysics. 18- Gehrels and Woodward (2013). When did modern rates of sea-level rise start? Global and Planetary Change. 19- Sallenger et al (2012) Hotspot of accelerated sea-level rise on the Atlantic coast of North America. Nature Climate Change. 20- Kopp et al. (2013) Does the mid-Atlantic United States sea level acceleration hot spot reflect ocean dynamic variability? Geophysical Research Letters. 21- Garner et al. (2018) Evolution of 21st Century Sea Level Rise Projections. Earth’s Future. UPDATES: 13 March 2020: This post was updated to include a comment by Thomas Frederikse.","Summary: The claim that sea level rise has been slow and constant, pre-dating industrialization appeared in several outlets, including American Thinker and The Global Warming Policy Forum, going viral in March 2020 with nearly 8,000 interactions on Facebook. This claim contradicts ample scientific evidence showing that the rate of sea level rise has increased over time, as seen in the figure below. Figure – Sea level data from the US Atlantic Coast shows an overall rise from 1850 to 2000, with the fastest increases occurring in the 20th century. Adapted from Kemp et al. 2011[1]. Sea level rise is primarily driven by glacial ice melting and the expansion of seawater as it warms. Although natural factors such as land mass movements and ocean circulation patterns influence sea levels, human-induced climate change is accelerating the rate of sea level rise[2,4]. Specifically, greenhouse gas emissions have increased global temperatures, causing ice sheets to melt and oceans to thermally expand, as Margot Saher describes in the reviewer comments below. Natural and anthropogenic drivers of sea level rise also differ across geographic locations. For example, the Atlantic Coast of North America shows faster rates of sea level rise compared to the global average[2]. A recent study found that these rapid rises in sea level occurred in the 20th and 18th centuries[2]. The claim that sea level rise is slow and constant misinterprets the results of this study. Although there were two periods of rapid increases in sea level, there were also periods of limited rise in sea level along the Atlantic Coast, showing the overall rate of sea level rise is not constant. Despite these fluctuations over time and across geographic regions, global average sea level rose faster in the 20th century than in any previous time period. Scientists’ Feedback: Roland Gehrels Professor, University of York: The blog is a misrepresentation of our paper [published in GRL[2]]. Sea-level rise in our study area (the North American Atlantic coast north of Cape Hatteras) has been neither slow nor gradual nor constant. We found that sea-level rise in the 20th century was the fastest (at least in the last 3,000 years—this we also published in PNAS in 2016 in a paper led by Bob Kopp[3]) but there was also a rapid sea-level rise, albeit somewhat slower, in the 18th century. The rates in both centuries are not slow at all; there haven’t been any other centuries in the last 3,000 years that saw similar rates. Sea-level during most of the 19th century did not rise by much, so the sea-level rise is not constant either; there was a clear break between the 18th and the 20th century. What it all means is that there is an underlying natural mechanism in this “hotspot”, which we hypothesize is related to Arctic ice melt and the North Atlantic Oscillation. In the 20th century (and in the future) this mechanism operates IN ADDITION to anthropogenic forcing, which was significant and since 1970 has been the dominant control on global sea-level rise (e.g. Slangen et al. 2016[4]; Dangendorf et al. 2015[5]; Kopp et al. 2016[3]). Our original press release is here: https://www.york.ac.uk/news-and-events/news/2020/research/sea-levels-atlantic/ The last sentence [in our paper] is quite clear (my emphasis in bold here): Our findings suggest that enhanced rates of sea level rise along eastern North America are not only symptomatic of human activity, but might additionally arise from natural processes in the climate system. Benjamin Horton Professor, Earth Observatory of Singapore: Please see the two papers that use a global dataset which clearly shows that the rate of [sea level rise] in the 20th century is faster than anything of the past 2000 and 3000 years respectively[1,3]. Jonathan Gregory Professor, University of Reading and UK Met Office Hadley Centre: I would say that the article in American Thinker is a misrepresentation of the state of science. Furthermore, Dr. Singer’s conclusion (in his second paragraph) is completely untrue. The GRL paper cited[2] doesn’t say anything about the causes of 20th-century global-mean sea-level rise. They are about sea-level change in a particular location. For the global mean, it is generally accepted that 20th-century sea-level change is partly anthropogenic and partly natural[5]. A substantial part of it is due to contraction of glaciers worldwide, beginning before the 20th century, and not likely to be anthropogenic. However, the increasing rate of glacier retreat and warming of the ocean, causing thermal expansion, is probably anthropogenic[4]. It is also generally accepted that sea-level in any particular location can show considerably different trends from the global mean, even for long periods, because of unforced variability in the climate system[3]. Margot Saher Lecturer, Bangor University, Wales, UK: Sea level is not level. Global sea level rises due to thermal expansion and ice melt, but neither of these processes leads to the same amount of sea level rise all over the globe. There are many aspects that cause this: vertical land movement, ocean currents, wind patterns, etc. Gehrels and Long wrote a good introductory text on that, be it applied to the UK[6]. That sea level is rising should surprise nobody; rising CO2 levels in the atmosphere lets the same amount of solar energy in, while letting less long-wave radiation out. It’s a question of simple physics that means the Earth system is warming, which leads to the oceans thermally expanding and ice bodies melting. And these effects have been extensively documented[7-10]. That sea level is not only rising but also accelerating has been found in a plethora of records, both from tide gauges (see figure above)[11,12], satellite measurements[13,14], proxy records[2,15] and combinations thereof[16-18]. The important thing here is that the global average records[17,12] show this increase, as when looking at individual reconstructions, the signal can be dominated by local effects. When looking at an individual record it is important to see it in context. One could, for example, look at the Stockholm tide gauge record (available on PSMSL.org); this shows a sea level drop. Does that prove that sea level isn’t rising at all? No, it means that Sweden is rising up after having been pushed down by the ice sheets of the last glacial period. Does a period of rapid pre-industrial sea level rise on the US east coast, as seen in Gehrels et al. (2020)[2], mean that sea level rise isn’t accelerating? Of course not. It just means that the various factors that determine sea level at that location can result in much more than average sea level rise there, and have done so in the past. This can happen again. And this means its citizens would be well-advised to be even better prepared for future sea level rise than people living in other areas along the US east coast. Thomas Frederikse Postdoctoral researcher, Jet Propulsion Laboratory/California Institute of Technology: Let’s start with the title: ‘New study shows sea level rise has been slow and a constant, pre-dating industrialization’. That statement is wrong, and does not come from the article it’s based on. A comprehensive 2016 studyunambiguously shows using proxy and modern sea-level records that 20th-century global-mean sea-level rise is larger than during any century over the past 3000 years[3]. The scientific article the text refers to sea level along the US East Coast, which is not representative for global sea level at all. Over the last 60 years or so, sea-level rise along the US East coast has been accelerating much faster than the global mean, and is therefore often called a sea-level hotspot[19]. There’s a lot of discussion of its causes[20], and it is not yet known whether this anomaly is human-caused or not. So, the article discusses an anomaly in regional sea level. Regional sea level often deviates a lot from global sea level, so this anomaly does not say much about the global mean sea level, and definitely not about sea level on Pacific islands mentioned in the article. The new study shows that similar anomalous acceleration patterns have happened during the 18th century as well, which implies that the anomalously high rate of sea level along the US east coast is not an indicator of anthropogenic climate change per se. Since this large acceleration comes on top of the global rise in sea level due to climate change[4,5], this study does not refute at all anthropogenic sea-level rise, and the news article deliberately frames it that way, despite the clear message in the conclusions: “Our findings suggest that enhanced rates of sea‐level rise along eastern North America are not necessarily symptomatic of anthropogenic forcing, as was argued in past work[19], but might arise from other forcing mechanisms in the coupled climate system. Our results also suggest that these multidecadal‐centennial periods of low or high sea level might dampen or amplify any future sea‐level signal that is generated by greenhouse‐gas forcing, and should be taken into account in projections of future coastal vulnerability and risk.” It’s in a sense similar to saying after a very hot summer, that because in the 18th century, we also had some hot summer that the climate isn’t changing. After misinterpreting the scientific article, the classic and debunked repertoire of Fred Singer and co is repeated, falsely claiming that sea-level rise projections are constantly being revised downwards. A thorough analysis of all available sea-level projections[21] shows that high-end sea-level rise projections generally project more sea-level rise since the IPCC report in 2007. Finally, the concluding takeaways are all factually wrong: “The takeaways include the realization that sea level rise is gradual and has been going on for centuries, may or may not be related in some small way to CO2 emissions, and can be adapted to because it is so slow.” Sea-level rise is not gradual Sea-level rise has not been going on for centuries Global sea-level rise is caused by CO2-induced thermal expansion of sea water and glacier and ice-sheet mass loss Many coastal locations inside and outside the US already struggle with its consequences"
https://science.feedback.org/review/data-from-glaciers-around-the-world-show-most-are-shrinking-as-a-consequence-of-global-warming/,Inaccurate,"Principia Scientific, IceAgeNow, 2016-11-26",90 percent of the world’s glaciers are growing.,,"Cherry-picking: This claim is based on a single study from 2015 which suggests that the East Antarctic Ice Sheet is growing, and ignores dozens of other published studies which contradict these findings. Furthermore, while the East Antarctic Ice Sheet accounts for over 80% of the world’s ice mass, that does not mean it represents 90% of the world’s glaciers. Overstates scientific confidence: The overall gain or loss of ice from the East Antarctic Ice Sheet is still being investigated. Recently improved satellite-based methods for measuring ice mass offer more accurate estimates, which do not corroborate the claim that this ice sheet is growing.","This claim is an inaccurate representation of a single study’s results, which concluded that the Antarctic Ice Sheet is gaining mass and is therefore not contributing to global sea level rise. Other scientific studies contradict the results of this study. There is also a large body of peer-reviewed research by glacial scientists which concludes that the Antarctic Ice Sheet is, in fact, contributing to sea level rise due to prominent ice loss on the West Antarctic Ice Sheet.",90 percent of the world’s glaciers are growing.,1 – Zwally et al. (2015) Mass gains of the Antarctic ice sheet exceed losses. Journal of Glaciology. 2 – Zemp et al. (2008) Global Glacier Changes: Facts and Figures. UNEP and World Glacier Monitoring Service. 3 – Scambos and Shuman. (2016) Comment on “Mass gains of the Antarctic ice sheet exceed losses” by H. J. Zwally and Others. Journal of Glaciology. 4 – McMillan et al. (2014) Increased ice losses from Antarctica detected by CryoSat-2. Geophysical Research Letters. 5 – Helm et al. (2014) Elevation and elevation change of Greenland and Antarctica derived from CryoSat-2. The Cryosphere.,"An article posted by IceAgeNow.info in November 2016 and republished on the blog Principia Scientific, makes this claim about the world’s glaciers based entirely on a single study published in the Journal of Glaciology in 2015 by Dr. H. Jay Zwally, a scientist at NASA, and colleagues[1]. The claim began trending on Facebook in early 2020 and received 1.6 million views on Facebook over the past 3 months. The study showed that the East Antarctic Ice Sheet (see Figure 1) is gaining ice faster than other parts of the Antarctic ice sheet are losing ice. IceAgeNow’s article claims that since Antarctica represents about 90% of the world’s glacial ice and the East Antarctic Ice Sheet holds the majority of that ice, this means that 90% of the world’s glaciers are growing. However, the article fails to mention conflicting results found in numerous other studies, and therefore presents a biased view of the scientific understanding of this topic. The Zwally paper’s results are, in fact, an outlier among similar studies of the Antarctic ice mass balance* and have been challenged by more recent papers. [*Mass balance is a measure of the overall ice gain or loss in a given year, and these results are given in meters water equivalent to account for varying densities of ice and snow.] Figure 1 – Map of the East and West Antarctic ice sheets (made by Carbon Brief). The Antarctic Ice Sheet holds much of the world’s glacial ice, but glaciers are widespread around the world near the poles and in alpine regions. Glaciers are individual bodies of ice that deform and flow under their own weight, following the topography beneath them. An ice sheet is a continent-spanning region of ice, within which a number of glaciers can be found at its edges. This means that Antarctica’s share of the world’s glacial ice mass is not the same as its share of the world’s number of glaciers. The World Glacier Monitoring Service (WGMS) has reported a clear trend of global glacial ice loss, as shown in Figure 2, for all glaciers and a subset of “reference glaciers” which have been continuously monitored since 1976[2]. Of the 151 glaciers included in the 2018 WGMS measurements, about 12% showed a trend of ice growth. Glaciers can grow either due to reduced losses from melting, sublimation, or calving, or due to increased additions from snowfall. Figure 2 – Cumulative mass balance (overall glacier growth or retreat) from 1945 to 2005 for all glaciers and a subset of continuously monitored “reference” glaciers. Source: World Glacier Monitoring Service[2]. Another figure (Figure 3) from a paper by Ted Scambos of the National Snow and Ice Data Center and Christopher Shuman from NASA’s Goddard Space Flight Center directly displays the differences between the Zwally paper’s results and those of 12 other published studies[3]. The figure compares ice mass changes in the Antarctic Ice Sheet as reported by each study. The Zwally paper’s results, as indicated by the brown rectangle in the figure, present the only data indicating an overall gain in mass to the Antarctic Ice Sheet. Therefore, the Zwally paper’s data are clear outliers to the estimates from other studies which indicate that Antarctic ice mass is declining. Figure 3 – Antarctic Ice Sheet mass balance estimates from studies published from 2012 to 2015. Each box represents the range of error (vertical) and the time span of the data (horizontal). Source: Scambos and Shuman (2015)[3]. Scambos and Shuman pointed to the methods of Zwally et al. as the reason for their vastly different estimates. Satellite methods are widely used to detect changes in elevation of the ice surface, which inform estimates of mass gain or loss over time. To ensure accurate measurements, a reference surface with a well understood elevation is needed for calibration. Zwally’s team used patches of open ocean as their reference surface, which Scambos and Shuman point out could be problematic because a dark surface, such as the ocean, provides a less accurate signal to satellites than do bright surfaces such as ice. The Zwally study also used data from different satellites than the more recent studies, which found much smaller elevation gains[4,5]. The author of the claim reviewed here also fails to recognize that even the Zwally paper’s results illustrate a decreasing snowfall trend, and it predicted that in about 20 years’ time, Antarctica would be losing ice mass and contributing to sea level rise. To wrap up, the IceAgeNow article claims that 90% of the world’s glaciers are growing, but according to the WGMS’s 2018 dataset, only about 12% of glaciers are gaining mass globally[2]. The article cites a single study which supports the claim that the Antarctic Ice Sheet is not contributing to sea level rise and does not consider numerous studies with differing results, therefore presenting a cherry-picked view of the body of research on the subject."
https://science.feedback.org/review/current-climate-warming-is-rapid-and-occurring-on-a-global-scale-unlike-past-periods-of-regional-climate-fluctuations/,Misleading,"PragerU, Patrick Moore, 2020-01-21",Of course the climate is changing. It always has. It always will.,,"Misleading: Misrepresents past climate epochs as similar and comparable to the current pattern of global climate change, though they were significantly smaller in spatial extent, magnitude, and rate of change.","Although periods of regionally warmer and cooler temperatures have been recorded over the last 2,000 years, the patterns of warming and cooling were not globally coherent. In contrast, the current period of climate warming is unprecedented, occurring simultaneously on 98%[1] of Earth’s surface and at a significantly faster rate than past fluctuations in global temperature.","Over the past 2,000 years, the globe has seen the Roman Warm Period, the cooler Dark Ages, the Medieval Warm Period, the Little Ice Age, a gradual 300-year warming. Of course the climate is changing. It always has. It always will.","1 – Neukom et al. (2019) No evidence for globally coherent warm and cold periods over the preindustrial Common Era. Nature. 2 – Neukom et al. (2019) Consistent multidecadal variability in global temperature reconstructions and simulations over the Common Era. Nat. Geosci. 3 – Marcott et al. (2013)A Reconstruction of Regional and Global Temperature for the Past 11,300 Years. Science. 4 – Wuebbles et al. (2017) Executive Summary: in: Climate Science Special Report: Fourth National Climate Assessment, Volume I. U.S. Global Change Research Program, Washington, DC, USA.","This claim made in a viral Instagram post and a video by PragerU states that Earth’s climate has always changed and always will, and cites as evidence past periods of climatic anomaly such as the Roman Warm Period and the Little Ice Age. Although the occurrence of such climate epochs is not disputed—they are well-known from both written records and paleoclimate proxies such as lake sediment cores and tree rings—these periods of climate fluctuation are not comparable to the current pattern of climate warming, contrary to the claim that “of course the climate is changing” today just as it had been in the past. The current period of climate warming is globally coherent, meaning that surface temperature warming is occurring simultaneously across the planet. In contrast, none of the climate epochs over the last 2,000 years were globally coherent, and past climate fluctuations were smaller in magnitude and changed at a slower rate than current surface temperature warming. Although the Little Ice Age (15th-19th century CE) is generally associated with cooler temperatures, the pattern of cooling during this epoch was not globally coherent. Using paleoclimate reconstructions, scientists at the University of Bern demonstrated that the temperature minimums during the Little Ice Age occurred hundreds of years apart in different regions[1]. The eastern Pacific region hit its coldest temperature by the 15th century, while northwestern Europe did not reach its temperature minimum until about 200 years later. The same is true for the other well-known periods of climate fluctuation that have occurred over the last 2,000 years, such as the Medieval Warm period (see Figure 1). In contrast, the same study showed that the current pattern of climate warming is occurring simultaneously across 98% of the planet’s surface (Figure 1c). The spatial and temporal coherence of the current warming period is unprecedented over the last 2,000 years, marking current climate change as fundamentally different from past regional climatic fluctuations. Figure 1 – Years with the warmest (A, B, C) and coldest (D, E) temperatures across the globe, based on paleoclimate reconstructions. Source: Neukom et al. 2019[1]. This study, along with additional paleoclimate reconstructions, shows that the magnitude and rate of temperature change during the current warming period are also significantly greater than what the planet has experienced over the last 2,000 years[2] (Figure 2). Figure 2 – Warming/cooling rates averaged across 51 years and based on paleoclimate records. Modern thermometer records shown in black. (Source: University of Bern.) Robust paleoclimate reconstructions extending even further back—to the beginning of the Holocene 11,000 years ago—show that the current global surface temperature is warmer than it was for 90% of the Holocene, and that the temperature by 2100 is projected to be warmer than the planet has experienced during recorded human history[3]. Furthermore, the rate of warming over the last century is about ten times faster than previous rates of long-term global temperature change in the last million years, even those occurring at the end of ice ages. This shows that the current pattern of climate warming is not comparable to past, natural fluctuations in climate. These findings support a plethora of other evidence that current climate warming is human-caused, not natural[4]."
https://science.feedback.org/review/sea-levels-have-risen-throughout-the-20th-century-contrary-to-claim-in-online-article/,Inaccurate,"Breitbart, Signs of the Times, James Delingpole, Vicki Batts, 2019-05-28",Scientists were caught 'adjusting' sea level data to create false impression of rising oceans,,"Factually Inaccurate: Multiple lines of evidence demonstrate that sea level rise occurred throughout the 20th century. Misleading: The claim that scientists were caught “adjusting” sea level data misrepresents the process scientists use to account for potential errors in historical sea level data. Cherry-picking: The claim highlights a single study, which has been formally refuted. The article does not include any of the research that has clearly shown rising sea levels over time.","Global average sea level has risen throughout the 20th century and continues to rise at an accelerating rate. Sea level rise primarily results from glacial ice melting and the expansion of seawater as it warms. Scientists do not arbitrarily adjust sea level data, but instead compare sea level measurements to stable benchmarks to generate accurate estimates of sea level change over time.",Scientists were caught 'adjusting' sea level data to create false impression of rising oceans [...] Scientists have found that sea levels are stable - and have been for the entirety of the 20<sup>th</sup> century.,,"Summary: The claim that sea levels have remained stable throughout the 20thcentury appeared in several outlets, including Breitbart and Signs of the Times, going viral in early 2020 with more than 800,000 views for the two articles on Facebook over the past three months. It contradicts numerous studies that clearly demonstrate a rise in global mean sea level[1], as you can see in the figure below. A recent IPCC report forecasts that global sea levels will continue to rise throughout the 21st century, with “unavoidable consequences for river runoff and local hazards.” A recent study estimated that global mean sea level (GMSL) rose 1.3 ± 0.2 mm per year from 1902 to 2012[1]. However, sea level rise accelerated between 1993 to 2012, increasing at a rate of 3.1 ± 1.4 mm per year[1]. This acceleration was primarily driven by high rates of sea level rise in the Indian Ocean and Southern Pacific. These findings contrast with the claim that “sea levels are stable,” which was based on a single study from 2017 which analyzed sea level change near three cities, all located along the Indian Ocean (Aden, Karachi, and Mumbai). The process of assessing historical changes in sea level and predicting future changes is complex and involves several key challenges, as described in Horton et al. (2018)[2]: “First, regional and local sea-level changes vary substantially from the global mean[3]. Understanding regional variability is critical to both interpreting records of past changes and generating local projections for effective coastal risk management[3]. Second, uncertainty is pervasive in both records of past changes and in the physical and statistical modeling approaches used to project future changes[4], and it requires careful quantification and statistical analysis.” Sea level changes differ across geographic locations for a variety of reasons. Wind and water density affect ocean circulation patterns, resulting in higher sea levels in some regions and lower sea levels in others. Land masses rise and sink over time as tectonic plates shift and ice sheets melt, reducing weight on the land’s surface. Because of this variation, a single geographic region cannot be used to draw conclusions about sea level stability on a global scale. The claim that “scientists were caught ‘adjusting’ sea level data to create false impression of rising oceans” misrepresents approaches used by scientists to account for potential errors in historical sea level data. Instruments used to measure sea level, called tide gauges, may be replaced or moved to new locations over time. To calculate actual changes in sea level despite movements of the tide gauges, sea level data is compared to a stable benchmark at each sampling site. The process of adjusting data based on benchmarks is not arbitrary, as Thomas Frederikse explains in the reviewer comments below. Figure – Global mean sea level (GMSL; A) and the rate of sea level change (B) based on 322 tide gauges measured from 1902-2012. Each color represents a different approach used to correct for movement of the tide gauges, uneven sampling across geographic regions, or the contribution of glacial ice sheet melt to sea level rise. From Dangendorf et al. (2017)[1]. Scientists’ Feedback: Thomas Frederikse Postdoctoral researcher, Jet Propulsion Laboratory/California Institute of Technology: This claim is utterly false and has been formally refuted[5]. The idea is that tide-gauge measurements show sea level relative to the measuring device. That’d mean, if the device is lifted, or moved to another location, you’d get a jump in your time series. To avoid these jumps, the Permanent Service for Mean Sea Level, the organization that collects a large global database of tide-gauge observations, requires that each record has a complete levelling history attached (called an “RLR diagram”). That means that surveyors regularly check the height of the tide gauge relative to a stable benchmark to ensure that the data shows sea-level changes and not instrument movements. When these movements occur, the levelling data is used to offset the impact of this movement. However, the original data without any adjustments for these instrument movements is also available. Aden [in Yemen] is one of these records for which levelling data is available[6]. The station shows a clear rise in sea level of about 12 cm since ~1900. Now basically, the authors [of the refuted study] call this full levelling data “arbitrary”, come up with some random alternative “adjustments”, not backed by any reasonable argument, and voila, their manipulated sea-level data doesn’t show any sea-level rise anymore. Then they infer from their falsified data, based on this and two other records that global sea level is stable. Sea-level reconstructions, which typically include hundreds of tide-gauge records, unanimously show that sea level has risen by 15 to 25 cm since 1900. Benjamin Horton Professor, Earth Observatory of Singapore: There is so much evidence from satellites, tide gauges, and geological records to show sea-level is rising[1]. For example, from my research, we have shown that the 20th-century rise was extraordinary in the context of the last three millennia—and the rise over the last two decades has been even faster[7]. Jonathan Gregory Professor, University of Reading and UK Met Office Hadley Centre: The paper by Parker and Ollier (2017) [that is cited in the claim] was rebutted by Rickards in the same journal later that year[5]. I understand from colleagues who are more familiar with this literature than me that Parker has published many other papers, some of them under another name of Boretti, containing incorrect analyses and misleading statements. References: 1- Dangendorf et al. (2017) Reassessment of 20th Century Global Mean Sea Level Rise.PNAS. 2- Horton et al. (2018) Mapping Sea-Level Change in Time, Space, and Probability.Annual Review: of Environment and Resources. 3- Milne et al. (2009) Identifying the causes of sea-level change. Nature Geoscience. 4- Church et al. (2013) Sea level change. In Climate Change 2013: The Physical Science Basis. 5- Rickards (2017) Comments on the Paper “Is the Sea Level Stable at Aden, Yemen?” by Albert Parker and Clifford D. Ollier in Earth Systems and Environment.Earth Systems and Environment. 6- Woodworth et al. (2009) Insight into Long Term Sea Level Change Based on New Tide Gauge Installations at Takoradi, Aden, and Karachi. International Hydrographic Review. 7- Kopp et al. (2016) Temperature-driven global sea-level variability in the Common Era.PNAS."
https://science.feedback.org/review/noaa-does-not-fraudulently-adjust-data-to-create-the-illusion-of-a-global-warming-trend-investors/,Inaccurate,"Investors' Business Daily, Anonymous, 2018-03-29","Using complex statistical models, [NOAA] change[s] the data to reflect not reality, but their underlying theories of global warming.",,"Factually Inaccurate: It is not true that data adjustments have falsely created the appearance of a global warming trend. Adjustments to temperature datasets are routinely performed to remove sources of error. Without these adjustments, the global warming trend since the late 1800s would in fact appear greater than it actually is. Many independent datasets support the accuracy and necessity of these adjustments.","Scientists routinely adjust temperature data to correct errors due to weather stations being moved to different locations or instruments being changed.. Historical changes to U.S. stations have caused the number of upward and downward temperature adjustments to be unequal, but this is not representative of the entire world. Overall, adjustments to temperature data reduce the apparent amount of long-term global warming—the opposite of exaggerating it.","Using complex statistical models, [NOAA] change[s] the data to reflect not reality, but their underlying theories of global warming[...] all of their temperature adjustments lean cooler in the distant past, and warmer in the more recent past.",,"Peter Thorne Professor, Maynooth University: [This comment was initially provided in response to a similar claim.] The central tenet of the claim appears to be that NOAA are nefariously adjusting past temperatures to be colder with the effect of making recent temperatures appear warmer. NOAA do, indeed, adjust historical temperature records, but the process by which they do so can hardly be termed nefarious. The data are made available on their website as the original data, the quality controlled and the homogenised versions on a station-by-station basis. The methods by which they undertake the analysis are fully documented in several papers in the peer-reviewed literature available from their website. The code they use to determine the adjustments is made available without restriction via their website. They have participated in a big intercomparison using blind benchmarks of a range of methods1. Their method ranked extremely highly and consistently removed real data issues while having an exceptionally low false detection rate. They followed-up with an in-depth assessment against a range of benchmarks to explicitly assess the performance of the algorithm in the contiguous United States. Both the multi-participant benchmarks and these bespoke benchmarks showed that their method consistently improves the data quality, but also consistently under-estimates the required large-scale adjustment. So, yes, the NOAA analysis cools the past. No, its not some nefarious black magic, just the opposite in fact. And, perhaps most concerningly, everything we know about the method suggests it is adjusting too little and not too much. 1 – Venema et al (2012) Benchmarking homogenization algorithms for monthly data, Climate of the Past Mark Richardson Research Associate, Colorado State University/NASA JPL: [This comment was initially provided in response to a similar claim review.] Raw data show more global warming since 1880 than is reported by NOAA [or shown in other datasets]. This is because NOAA “adjusts” temperature data to fairly compare different measurement times, places, and technologies. The cooling effect of adjustments on global temperatures has been shown lots of times, such as with the graph below for 1880—2013 temperatures. A small group of conspiracy theorists flip this reality by “cherry picking”, which means using a fraction of the data to prop up claims that are false globally. It’s the sort of technique that would insist that this is a 100% blue cherry tree. NOAA scientists know that afternoons tend to be warmer than early mornings so it would be dumb to mix, for example, 1940s morning temperature readings with 2010s afternoon readings without accounting for this. They refuse to do obviously, provably dumb things so they carefully correct the data for a fair comparison. In the U.S., thermometers used to be read largely in the afternoon but now tend to be read in the morning1. This means that adjustments in the U.S. are warming, making it a popular choice for hints at conspiracy. There are ways to judge whether new claims are credible. Firstly, do they mention that global adjustments are cooling overall? Secondly, do they discuss reasons for adjustments including measurement time? If the answer is “no” to either then the author is hiding relevant information or is clueless about the topic and you should be very sceptical. Fortunately the scientific method can reliably test new claims through submissions to scientific journals for peer review, which tends to filter out obvious dumb mistakes like ignoring how afternoons are warmer than early mornings. Blog posts, think tanks and newspapers have no such filter. We know that NOAA’s adjustments improve things since they’re tested and updated whenever issues are found. For example, even a blogger who’s hostile to climate science results published a paper confirming that the NOAA U.S. average temperature changes are solid2. Another study by an independent “red team”, partly funded by a Koch foundation, supported NOAA’s conclusions3. I was involved with a check of NOAA’s ocean record using infrared scans from satellites4. The satellites supported NOAA’s results despite baseless & hysterical accusations that had been thrown at the scientists. After more than a decade of being relentlessly wrong, it’s time to be very careful with any new conspiracy claims aimed at the temperature records. 1-Vose et al (2003) An evaluation of the time of observation bias adjustment in the U.S. Historical Climatology Network, Geophysical Research Letters 2-Fall et al (2011) Analysis of the impacts of station exposure on the U.S. Historical Climatology Network temperatures and temperature trends, Journal of Geophysical Research: Atmospheres 3-Rohde et al (2012) A New Estimate of the Average Earth Surface Land Temperature Spanning 1753 to 2011, Geoinformatics & Geostatistics: An Overview 4-Hausfather et al (2017) Assessing recent warming using instrumentally homogeneous sea surface temperature records, Science Advances Victor Venema Scientist, University of Bonn, Germany: [These comments were initially provided in response to a similar claim.] To estimate how much the world has warmed, other changes need to be removed from the observations made at weather stations, observing ships and buoys. For example, if the surrounding of a station becomes more urban this often causes a warming that is local and needs to be removed to estimate the amount the world has truly warmed. Similarly when such a station moves to a better location, which is cooler, such a cooling jump needs to be removed for an accurate warming estimate. When it comes to the global mean temperature the main effect that needs to be removed is that in the past many sea surface temperature observations were made by hand with buckets and nowadays are made automatically at the water inlet of ships. While the water is hauled on deck and the thermometer adapts to the water temperature, the sea water evaporates and cools. Old measurements are thus 0°C to 0.4°C (0.7°F) too cold. Source: UK MetOffice In the unscientific formulation of [some], this means that the adjustments for this effect make the past warmer and the recent temperatures colder. But overall, the estimated global warming actually becomes smaller when taking into account all the adjustments—the opposite of [that claim]. [See figure in Mark Richardson’s comment above.] The adjustments climatologists make for land station data do make the warming greater. But the ocean adjustments (which reduce the warming trend) are more important for the global average. How large the adjustments need to be depends on how many other changes there were. The adjustments in the United States of America are relatively large, mainly due to two effects. In the past the thermometers were read more often in the afternoon, while nowadays they are read more often in the morning. The estimates of the daily average temperature based on minimum and maximum temperature thermometers are a bit colder in the morning than in the afternoon. A particularly cold morning can affect the observed minimum temperature of two days and a very hot afternoon the maximum temperature of two days. The temperature used to be measured with a thermometer in a Cotton Region Shelters in the USA. Nowadays they are mostly made using an Automatic Weather Station. These Automatic Weather Stations on average measure a lower temperature because they heat up less standing in the sun. The difference is especially large for the maximum temperature and for the summer. Comparing old summer maximum temperature with those of today would not be comparing like with like. And even if we had not invented the thermometer we would know it is warming: Glaciers are melting, from the tropical Kilimanjaro glaciers, to the ones in the Alps and Greenland. Arctic sea ice is shrinking. The growing season in the mid-latitudes has become weeks longer. Trees bud and blossom earlier. Wine grapes can be harvested earlier. Animals migrate earlier. The habitat of plants, animals and insects is shifting poleward and up the mountains. Lakes and rivers freeze later and break up the ice earlier. The oceans are rising."
https://science.feedback.org/review/co2-emissions-from-human-activities-have-imbalanced-the-atmospheric-carbon-budget-significantly-contributing-to-climate-change-contrary-to-online-claim-issues-insights/,Misleading,"Issues & Insights, I&I Editorial Board, 2019-08-26",Less than 5% of carbon dioxide emissions are produced by man [... they] can’t cause 30% of today’s atmospheric carbon dioxide,,"Fails to grasp significance of observation: Human activities produce less carbon dioxide than natural processes, but this does not mean that human-caused emissions are insignificant in the atmospheric carbon budget. Carbon dioxide emissions produced by humans since the beginning of the Industrial Revolution have brought an imbalance to the (previously balanced) global carbon cycle, which has led to an unprecedented rise in atmospheric carbon dioxide concentrations. Misrepresents source: The article leans on findings from the Intergovernmental Panel on Climate Change’s Fourth Assessment Report but uses the results out of context to support an inaccurate statement.","Carbon dioxide is a greenhouse gas released by natural processes as well as by human activities. The rapid rise in carbon emissions from burning fossil fuels beginning during the Industrial Revolution upset the natural balance in the global carbon cycle. Human-caused carbon emissions outpaced the ability of natural carbon sinks to absorb excess carbon dioxide, resulting in a rise in atmospheric concentrations from 280 to about 415 parts per million in 2020.","Less than 5% of carbon dioxide emissions are produced by man. [...] Human carbon dioxide, which is less than 5% of natural carbon dioxide, can’t cause 30% of today’s atmospheric carbon dioxide","1 – Rubino et al (2013)A revised 1000 year atmospheric δ13C‐CO2 record from Law Dome and South Pole, Antarctica, Journal of Geophysical Research: Atmospheres 2 – Climate Change 2014: Synthesis Report of the IPCC Fifth Assessment Report. Contribution of Working Groups I, II, and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. IPCC, Geneva, Switzerland. 3 – Climate Change 2007: Fourth Assessment Report. The physical science basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press. 4 – Peters et al. (2020) Carbon dioxide emissions continue to grow amidst slowly emerging climate policies. Nature Climate Change. UPDATES: 11 Feb. 2020: Michael Henehan reviewed this post for accuracy.","Summary: This claim, which was published in August 2019 on the website Issues & Insights in an article titled “A Short List Of Facts Global Warming Alarmists Don’t Want To Face”, has been viewed more than 105,000 times on Facebook in the last three months. The article argues that, since human emissions of carbon dioxide (CO2) are smaller than the total amount naturally circulating in the atmosphere, they cannot have a great influence on climate change. While it is correct that anthropogenic emissions of CO2 are less than the amount produced and absorbed by natural processes, the author fails to grasp that CO2 emissions produced by human activities are significant because they generate an imbalance between CO2 sources and sinks. CO2 is a greenhouse gas, naturally released by the ocean, by soil, and by respiring organisms. These sources are only one part of the carbon cycle, a process in which CO2 flows between the oceans, solid Earth, biomass, and the atmosphere. So-called sinks, which include the oceans, soil, and vegetation, remove CO2 from the atmosphere. Based on ice core data, scientists have worked out that the concentration of CO2 in parts per million (ppm) hadremained relatively constant for thousands of years. For ten thousand years before the Industrial Revolution, the concentration of CO2 remained between 260 and 280 ppm. During this time, the carbon cycle was balanced. Human activities, such as fossil fuel combustion, changes in land use, deforestation, and cement production, add to the amount of CO2 emitted into the atmosphere. Earth’s natural carbon sinks are unable to absorb the entire volume of CO2 that humans produce. Currently, natural sinks can absorb a little more than half of human CO2 emissions, with half of this amount going into the oceans and half into plants and soil. The remainder of human emissions cannot be absorbed and remain in the atmosphere. As a result, atmospheric CO2 concentrations have risen from around 280 ppm in the eighteenth century to about 415 ppm in 2020. In the 1950s, Charles David Keeling and other scientists began observing CO2 concentrations at Mauna Loa Observatory, which have steadily increased to the present day. The source of the CO2 added to the atmosphere can also be determined from the isotopes of carbon in the air. Themeasured change in atmosphericcarbon-14, carbon-13, and carbon-12 shows that the CO2 added to the atmosphere has come from fossil fuel burning and deforestation, rather than volcanoes or other sources[1]. Figure — The Keeling Curve, from 1700 to the present: The early data was derived from ice cores and the data since 1958 was collected at Mauna Loa Observatory. Credit: University of California San Diego, Scripps Institution of Oceanography, 2020. Source.The very IPCC report that the article cites in fact concluded that “CO2 emissions from human activities are considered the single largest anthropogenic factor contributing to climate change.”[3] And the most recent Fifth IPCC Assessment Report stated that, “About half of the cumulative anthropogenic CO2 emissions between 1750 and 2011 have occurred in the last 40 years (high confidence).”[2] In addition, despite climate change mitigation policies, a recent study in Nature Climate Change revealed that global, anthropogenic CO2 emissions rose again in 2019.[2] The volume of anthropogenic CO2 released today is, therefore, larger than the number mentioned in the Fourth Assessment Report. The vast body of scientific research agrees that recent increases in carbon emissions are due to human activities. The IPCC Fourth Assessment Report succinctly states: “Yes, the increases in atmospheric CO2 and other greenhouse gases during the Industrial Era are caused by human activities.”[3] Similarly, Ralph Keeling, a geochemist at the Scripps Institution of Oceanography at the University of California San Diego wrote: “The rise in CO2 is unambiguously caused by human activity, principally fossil-fuel burning. This is clear from the numbers: We know how much fossil fuel is converted into CO2 each year and emitted into the atmosphere. The CO2 doesn’t all stay there because some enters the ocean and some is taken up by photosynthesis, which ends up in land plants and various types of biomatter. Carbon atoms are not created or destroyed in any of these processes, […]. It’s true that atmospheric CO2 has almost certainly been higher than present in Earth’s distant past, many millions of years ago. But because fossil-fuel burning is not natural, the recent carbon increases in the atmosphere, oceans, and land biosphere cannot be natural either. [….] even though the levels of CO2 in the air may not be unprecedented, the pace of rise probably is. Few if any natural processes can release fossil carbon into the atmosphere as fast as we humans are doing it now via the extraction and burning of fossil fuels.“ (The full quote can be found here.) While an atmospheric CO2 concentration of 415 ppm is not unprecedented in the planet’s 4.5 billion year history, the pace of its recent increase is unprecedented in at least the last 800,000 years, based on data from ice core records.“Increases in CO2 never exceeded 30 ppm [in any previous 1,000-year period in the past 650,000 years]—yet now CO2 has risen by 30 ppm in just the last 17 years.”[3] The IPCC Fifth Assessment Report shows that this can only be attributed to the increased pace of human industrialization, growing economies and populations.[2]"
https://science.feedback.org/review/claims-of-a-coming-30-year-mini-ice-age-are-not-supported-by-science-the-sun/,Incorrect,"Express, The Sun, Harry Pettit, Sean Martin, 2020-02-02",Earth about to enter 30-YEAR ‘Mini Ice Age’,,"Factually Inaccurate: The most recent forecast from NOAA's Space Weather Prediction Center (from December 2019) predicts that the next solar cycle will be similar to the one that is currently ending.  Misleading: Even if an extended ""grand solar minimum"" were to occur, it would not produce marked global cooling.","Scientists cannot predict whether grand solar minimum, which is a decades-long period of lower solar activity, is coming. But even if one occurred, the consequences for average global temperatures would be minimal. Human-caused greenhouse gas emissions will continue to impact average temperatures much more strongly than solar activity cycles.","EARTH could be braced for a ‘mini ICE-AGE' as experts warn a solar minimum could last until the 2050s. [...] According to Nasa, the Sun will reach its lowest activity in over 200 years in 2020.",,"UPDATE (12 Feb. 2020): The Sun has significantly rewritten this article, including changing the headline to “Claim that Earth will enter ‘mini Ice Age’ for 30 years is wrong, top scientists reveal“. It now reads, in part: “One researcher warned that the Sun entering a natural ‘hibernation’ would trigger food shortages and temperature slumps – but current data suggests this is completely untrue.” While the article does not name or link to Climate Feedback’s review, it quotes from Doug Biesecker’s comment below. While some of the original article remains, the author has added qualifiers such as “While the Maunder Minimum occurred during a [grand solar minimum], most scientists think several factors contributed to the cold snap.“ Several articles repeat a claim (seen frequently at certain outletslike The Express) that a “mini ice age”, triggered by an extended period of unusually low solar activity is on the horizon. There are two problems with this claim: 1) the solar prediction does not reflect a consensus of scientists, and 2) an extended period of unusually low solar activity would not cause global cooling. The claim of a coming “grand solar minimum” (a period during which several 11-year solar cycles in a row remain abnormally weak) in this article at The Sun seems to come from interpretations of a June 2019 NASA press release about a single study on the persistent 11-year cycle in solar activity. The press release states: “The forecast for the next solar cycle says it will be the weakest of the last 200 years. The maximum of this next cycle—measured in terms of sunspot number, a standard measure of solar activity level—could be 30 to 50% lower than the most recent one.” The article containing the claim misstates this conclusion, writing that “the Sun will reach its lowest activity in over 200 years in 2020”. While the low point marking the end of the last solar cycle and the start of the next one will occur in 2020, the study did not conclude that the minimum point, specifically, would be the weakest. Rather, it was referring to the 11-year cycle as a whole. More importantly, the most recent major solar cycle forecast came from NOAA’s Space Weather Prediction Center. This group periodically convenes an international panel of solar scientists to create consensus forecasts. The panel’s December 2019 forecast states that the upcoming solar cycle 25 “will be average in intensity and similar to Cycle 24”, which is the solar cycle ending in 2020. Source: NOAA SWPC As for the effects of an extended period of low solar activity on global temperatures, the article warns that it would cause a “mini ice age” and up to 1°C global cooling, a prediction that is attributed to Valentina Zharkova, an astrophysicist at Northumbria University who is quoted in virtually every “mini ice age” news story that gets published. However, as explained in the scientists’ comments below, this does not accurately reflect the best understanding of climate science. The article containing this claim, like others before it, cites as evidence the Maunder Minimum, an approximately 70-year period of low solar activity beginning in the mid-1600s. The article claims that “temperatures plummeted across the globe” during this period. However, the cooler centuries around the Maunder Minimum were largely the result of major volcanic eruptions, not solar activity. The potential impact of a similar extended period of low solar activity is estimated to be only 0.1-0.2°C globally. Doug Biesecker, Space Weather Prediction Center, NOAA: [Dr. Biesecker was co-chair of NOAA’s Solar Cycle 25 Prediction Panel.] There is no evidence we are headed into a grand minimum. With Cycle 25 predicted to be similar to Cycle 24 [2009-2020], we do not see anything approaching a grand minimum, at least not in the near future. What we cannot say is what Cycle 26 will look like—mainly because no one has a demonstrated method for predicting that far ahead. As for solar minimum, the panel only addressed the timing of minimum, not the intensity. However, it would be fair to say that no one on the panel expects an extreme minimum. Based on the panel prediction of minimum occurring in April of 2020 (+/-6 months), we would expect this minimum to be very similar to the last minimum between Cycles 23 and 24. Michael Lockwood Professor of Space Environment Physics, University of Reading: [This comment is taken from an evaluation of a similar statement.] The Maunder minimum [mentioned in the article] was NOT (repeat NOT) a period of decades of freezing weather. It was a period when Europe had a higher fraction of cold winters but summers were, if anything, warmer in the Maunder minimum (as seen, for example, in the central England Temperature measurements) and paleoclimate data show a longer interval of slightly lower global temperatures (often massively misleadingly called the “little ice age”) which began long before the Maunder minimum and didn’t end until after the Maunder minimum was over. The idea that the Maunder minimum gave periods of unremitting cold is just wrong—it is often quoted but it is totally wrong. The Figure below (from Owens et al paper1) shows any drop that could possibly be associated with the Maunder minimum is 0.2 °C (and Owes et al show that is not statistically significant). Figure – A comparison of solar activity and northern hemisphere climate from AD 800 to AD 2016. Top: Sunspot number, from direct telescopic observations (black) and reconstructed on the basis of 14C concentrations in tree trunks (red). Bottom: Northern hemisphere temperature anomaly, ΔT, (relative to the 1961–1990 mean) for paleoclimate reconstructions, as presented in the IPCC fifth assessment report. Colours, from white through red, show the probability density function (PDF), while the white line shows the PDF maximum value (or mode).The blue line shows ΔT from the instrumental record (HadCRUT4). (Source) 1- Owens et al (2017) The Maunder Minimum and the Little Ice Age: An update from recent reconstructions and climate simulations, Journal of Space Weather and Space Climate Georg Feulner Senior Scientist, Potsdam Institute for Climate Impact Research (PIK): [This comment taken from an evaluation of a similar statement.] While regional and seasonal effects might be larger, the expected global temperature response to a future grand solar minimum similar to the Maunder Minimum is a cooling of about 0.1°C. It should be pointed out that this cooling would occur on the background of current anthropogenic warming which is about a factor of 10 larger. To claim that temperatures will fall dramatically is thus not really justified. It is also clear from these numbers that a future grand solar minimum (which would last only for a few decades anyway) would not save us from global warming, as we have shown in a scientific paper and explained here. The marginal temperature differences between warming scenarios with and without a future Maunder Minimum is illustrated here: Figure – Rise of global temperature for two different emission scenarios (A1B, red, and A2, magenta). The dashed lines show the slightly reduced warming in case a Maunder-like solar minimum should occur during the 21st century. The blue line represents global temperature data. Source: PIK."
https://science.feedback.org/review/simple-measurements-demonstrate-that-co2-is-a-greenhouse-gas-tim-ball/,Inaccurate,"Technocracy.news, Tim Ball, 2018-09-13",CO2 is not a greenhouse gas.,,Factually Inaccurate: The behavior of CO2 as a greenhouse gas is a consequence of basic physics and can be confirmed by simple measurements. Flawed Reasoning: The fact that CO2 can act as a feedback to climate changes triggered by other factors in no way shows that it isn't a greenhouse gas.,"Laboratory measurements first established that CO2 is a greenhouse gas in the 1850s—a result that is easily confirmed today. This means that it absorbs radiation at infrared wavelengths, allowing sunlight to pass through to the Earth but trapping heat that is emitted back to space.","The most important assumption behind the AGW theory is that an increase in global atmospheric CO2 will cause an increase in the average annual global temperature. The problem is that in every record of temperature and CO2, the temperature changes first. Think about what I am saying. The basic assumption on which the entire theory that human activity is causing global warming or climate change is wrong[...] In short, CO2 is not a greenhouse gas.",,"Greenhouse gases are gases that allow sunlight to pass through, but absorb infrared radiation (heat) emitted by the Earth back toward space. They do this because the molecules are only excited by radiation at very specific wavelengths (a consequence of quantum mechanics). In greenhouse gases, those wavelengths are mainly found in the infrared portion of the spectrum, rather than the visible or ultraviolet. This behavior was demonstrated in laboratory measurements by physicist John Tyndall in 1859. Since then, it has been confirmed countless times by instruments that measure light spectra. It can even be demonstrated with nothing more than an infrared camera and a candle. Increasing the concentration of CO2 in the atmosphere increases its heat-trapping effect, warming the atmosphere. Humans are doing this today primarily by burning fossil fuels and clearing forests. But in the past, there have been other drivers of warming like the slow-changing cycles in Earth’s orbit that controlled the timing of the ice ages. That initial warming influence was amplified by releases of CO2 into the atmosphere1. Whatever the source, an addition of CO2 to the atmosphere will have the same effect: increasing temperatures by trapping more infrared radiation. 1- Sigman et al (2010) The polar ocean and glacial cycles in atmospheric CO2 concentration, Nature Patrick Brown Assistant Professor, San Jose State University: [This comment is taken from an earlier review of a similar claim.] The primary empirical evidence that greenhouse gasses cause global warming is the absorption (as a function of wavelength of radiation) of gasses like CO2, CH4and N2O. This was discovered in 1859 by John Tyndall and has become a part of fundamental physics. Anyone can check this empirical relationship at any time with an absorption spectroscopy device. The empirical evidence that increases in greenhouse gas concentrations (from fossil fuel burning) are the primary cause of century-scale warming is that observed global temperatures have risen in line with what would be expected from the observed increase in greenhouse gas concentrations and observations of natural drivers of climate change (e.g. solar output and volcanic eruptions) indicate that natural drivers are not causing warming. Baird Langenbrunner Associate Editor, Nature Climate Change: [This comment is taken froman earlier reviewof a similar claim.] First, greenhouse gases are well studied, and their properties are nonnegotiable: They absorb and re-emit longwave radiation, whether they’re in a laboratory setting or in the real atmosphere. To back this up with historical evidence, scientists have known since the 1860s that CO2is a greenhouse gas and since the 1890s that this will affect the heat budget of the Earth through warming. Even then,these claimswere based on empirical evidence, and they’re supported by decades of laboratory research. Second, the link between increased greenhouse gas concentrations and warming continues to be supported by research in the last two decades. One study from 2001[1]used satellites to measure the type of energy entering and exiting Earth’s atmosphere and concluded that increases in greenhouse gases were responsible for extra heat measured between 1970 and 1997. The authors state that their results “provide direct experimental evidence for a significant increase in the Earth’s greenhouse effect that is consistent with concerns over radiative forcing of climate.” (Here, the term “radiative forcing” refers to the extra energy trapped in the atmosphere by greenhouse gases, cause warming.) A more recent study[2]arrived at similar conclusions, confirming predictions of the greenhouse effect in Earth’s atmosphere and providing “empirical evidence of how rising CO2levels … are affecting the surface energy balance.” In other words, rising CO2was linked directly to warming, even when things like plant uptake of CO2were considered. 1 – Harries et al (2001)Increases in greenhouse forcing inferred from the outgoing longwave radiation spectra of the Earth in 1970 and 1997, Nature 2 – Feldman et al (2015)Observational determination of surface radiative forcing by CO2from 2000 to 2010, Nature Mark Richardson Research Associate, Colorado State University/NASA JPL: [This comment is taken from an earlier review of a similar claim.] Global warming is measured fact. Working out the culprits has been like Crime Scene Investigation: Physics Edition. Some evidence comes from a facility in Billings, Oklahoma. Parts of air like water vapour and carbon dioxide naturally glow with infrared heat at very specific frequencies. The Billings site has a device that measured an incredibly precise “fingerprint” of the sky’s heating. Investigators reported in 20151that they found fingerprints across the sky with a clear match on the heating trigger. Below the blue line is the file fingerprint for carbon dioxide (CO2) heating, which we release into the air when we do things like burn coal & oil. This file fingerprint comes from basic physics backed by precise lab readings. The red line is the measured fingerprint in the sky over Billings and is a rock solid match. Each spike is extra heat coming down from the extra CO2 molecules that is heating us up. Measurements in Alaska and from satellites2confirm this. This is just one slide in the huge folder of empirical evidence showing human activity to be the main cause of recent warming. 1 – Feldman et al (2015) Observational determination of surface radiative forcing by CO2 from 2000 to 2010, Nature 2 – Harries et al (2001) Increases in greenhouse forcing inferred from the outgoing longwave radiation spectra of the Earth in 1970 and 1997, Nature Christopher Colose Research Scientist, SciSpace LLC, NASA Goddard Institute for Space Studies: [This comment is taken from an earlier review of a similar claim.] Claims that “CO2 led temperature in the past, therefore cannot have caused it to rise” originated over a decade ago from a misrepresentation of ice core research (that itself has been subject to significant refinements in dating). It was based on the fallacy that since other factors influence climate (in this case, changes in the Earth-Sun geometry) and that the carbon cycle is affected by climate, the converse cannot be true. Of course, this is not logically coherent, and in practice is wrong since the radiative effect of CO2 is well-established. Indeed, CO2 would not be expected to fluctuate on its own 100,000 year timescale on its own, independent of the climate. In fact, more recent research* shows that CO2 still led global temperatures and the full deglacial process, unlike in older literature that examined only Antarctic sites. CO2 has also “led” global temperature on geologic timescales, and is largely responsible for how Earth’s temperature evolved over the last 50 million years. There are many ways to change the partitioning of carbon between the Earth and atmosphere, and how this happens is not relevant for the fact that if more CO2 is in the atmosphere, the planet will get warmer. Today, however, the excess source of carbon to the atmosphere is from humans. Shakun et al (2012) Global warming preceded by increasing carbon dioxide concentrations during the last deglaciation, Nature Lauren Simkins Assistant Professor, University of Virginia: [This comment is taken from an earlier review of a similar claim.] Ice core records of past greenhouse gas and atmospheric temperature change1, coupled with records of ocean temperature and circulation changes2, indicate that there are complex feedbacks between earth-atmosphere-ocean changes that lead to naturally variable greenhouse gas changes. In some cases during past deglaciations, increases in CO2 have lagged methane (CH4) increases and associated atmospheric temperature rise, owing to natural processes that induce greenhouse gas release into the atmosphere. This is not the case for twentieth century and beyond human-induced atmospheric CO2 and temperature increases. Regardless of the source and cause of atmospheric CO2 increase, it will have a warming effect. Basic science does not change; CO2 is a greenhouse gas that is released into the atmosphere by burning of fossil fuels and leads to atmospheric warming. 1- Monnin et al (2001) Atmospheric CO2 Concentrations over the Last Glacial Termination, Nature 2- Skinner et al (2010) Ventilation of the Deep Southern Ocean and Deglacial CO2 Rise, Science Jeremy Fyke Postdoctoral researcher, Los Alamos National Laboratory: [This comment is taken from an earlier review of a similar claim.] In the natural Earth system, CO2 release acted as a feedback of naturally-forced change (e.g. due to millennial-scale, gradual, changes in the Earth’s orbit). Thus, CO2 is clearly established as an important forcer of, for example, ice ages. This demonstrates it’s effectiveness as a radiative gas. Now, of course, the situation is flipped because humans are actively emitting CO2. This is why it is now a “forcer” rather than a “feedback”. This change in no way impacts our century-old understanding of how CO2 warms the climate."
https://science.feedback.org/review/facebook-meme-incorrectly-claims-past-climate-variations-contradict-human-influence-on-current-climate/,Incorrect,"Facebook, Anonymous, 2020-01-02",The idea that 'climate change' is new or is caused by Humans is nonsense.,,"Flawed reasoning: The existence of ""natural"" climate changes in the past does not mean human activities are incapable of causing climate change today. Fails to provide correct physical explanation: Multiple lines of evidence demonstrate that human-caused greenhouse gas emissions are causing global warming.","Many lines of evidence have enabled scientists to conclude that humans are responsible for global warming. Physics dictates that increased concentrations of greenhouse gases in the atmosphere trap additional heat in Earth's climate system, and human-caused emissions of greenhouse gases have increased those concentrations. Climate has changed in the past for a number of reasons, and studying those events helps scientists understand the way the climate system works.",The environment of Earth has been continually changing for 4.5 billion years! The idea that 'climate change' is new or is caused by Humans is nonsense.,,"A meme that has been widely shared on social media claims that human influence on climate is nonsense because the climate has changed in the past. Climate changes in Earth’s past are known because they have been studied by climate scientists and geologists. Past events have been caused by factors such as slow-changing cycles in Earth’s orbit, volcanic activity, and even the gradual motions of plate tectonics1. Part of the understanding of Earth’s climate system comes from the study of past events. That understanding allows scientists to evaluate the climatic effects of human activities. Currently, the concentrations of carbon dioxide and other greenhouse gases are increasing because of human-caused emissions, not something like volcanic eruptions or natural activity. And no matter the cause of increasing carbon dioxide, it results in a stronger greenhouse effect and warmer temperatures. The 2017 US National Climate Assessment summarized the science on the cause of climate change this way: “This assessment concludes, based on extensive evidence, that it is extremely likely that human activities, especially emissions of greenhouse gases, are the dominant cause of the observed warming since the mid-20th century. For the warming over the last century, there is no convincing alternative explanation supported by the extent of the observational evidence.” The actions required to limit further climate change are more complicated than simply establishing a carbon tax. But whatever type of policy is used to encourage the transition, the physics of the climate system dictate that human-caused greenhouse gas emissions must be eliminated to halt the warming trend. If concentrations of greenhouse gases stop increasing, the amount of energy they trap in Earth’s climate system will also stop increasing. 1-Macdonald et al (2019) Arc-continent collisions in the tropics set Earth’s climate state, Science Advances Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: This comment comes from an evaluation of a similar claim. We are well aware that there are climatic fluctuations through geological time. Huge numbers of scientists study how the Earth’s climate has fluctuated before, and we know what caused those changes. Current warming is not related to any natural climate cycle, or process, or astronomic phenomenon. Richard Betts Professor, Met Office Hadley Centre & University of Exeter: This comment comes from an evaluation of a similar claim. The Earth’s climate has always varied, even before humans began to influence it. Climate scientists have always been very clear about this. But human-caused emissions of CO2and other greenhouse gases have now added a new cause of climate change in addition to the existing causes of natural climate variability. Mark Richardson Research Associate, Colorado State University/NASA JPL: This comment comes from an evaluation of a similar claim. Here are logically identical arguments: “England scored goals before Harry Kane, so Harry Kane can’t score goals” Or in American English: “The New England Patriots scored touchdowns before Rob Gronkowski, so Rob Gronkowski can’t score touchdowns”. Or more simply: “Fires happened before humans, so humans can’t cause fires”.So if you agree with this logic and that humans aren’t causing CO2to rise, you also have to believe that Harry Kane and Rob Gronkowski never scored anything and could never score anything, and that no fire has been caused by a human ever.Human-caused global warming, goals by Harry Kane, touchdowns by Rob Gronkowski, and fires set by people are all in the same boat. We have enormous evidence that they exist. Patrick Brown Assistant Professor, San Jose State University: This comment comes from an earlier review of a similar claim. The primary empirical evidence that greenhouse gasses cause global warming is the absorption (as a function of wavelength of radiation) of gasses like CO2, CH4and N2O. This was discovered in 1859 by John Tyndall and has become a part of fundamental physics. Anyone can check this empirical relationship at any time with an absorption spectroscopy device. The empirical evidence that increases in greenhouse gas concentrations (from fossil fuel burning) are the primary cause of century-scale warming is that observed global temperatures have risen in line with what would be expected from the observed increase in greenhouse gas concentrations and observations of natural drivers of climate change (e.g. solar output and volcanic eruptions) indicate that natural drivers are not causing warming. Baird Langenbrunner Associate Editor, Nature Climate Change: This comment comes from an earlier review of a similar claim. First, greenhouse gases are well studied, and their properties are nonnegotiable: They absorb and re-emit longwave radiation, whether they’re in a laboratory setting or in the real atmosphere. To back this up with historical evidence, scientists have known since the 1860s that CO2is a greenhouse gas and since the 1890s that this will affect the heat budget of the Earth through warming. Even then,these claimswere based on empirical evidence, and they’re supported by decades of laboratory research. Second, the link between increased greenhouse gas concentrations and warming continues to be supported by research in the last two decades. One study from 2001[1]used satellites to measure the type of energy entering and exiting Earth’s atmosphere and concluded that increases in greenhouse gases were responsible for extra heat measured between 1970 and 1997. The authors state that their results “provide direct experimental evidence for a significant increase in the Earth’s greenhouse effect that is consistent with concerns over radiative forcing of climate.” (Here, the term “radiative forcing” refers to the extra energy trapped in the atmosphere by greenhouse gases, cause warming.) A more recent study[2]arrived at similar conclusions, confirming predictions of the greenhouse effect in Earth’s atmosphere and providing “empirical evidence of how rising CO2levels … are affecting the surface energy balance.” In other words, rising CO2was linked directly to warming, even when things like plant uptake of CO2were considered. 1 – Harries et al (2001)Increases in greenhouse forcing inferred from the outgoing longwave radiation spectra of the Earth in 1970 and 1997, Nature 2 – Feldman et al (2015)Observational determination of surface radiative forcing by CO2from 2000 to 2010, Nature"
https://science.feedback.org/review/climate-change-bushfires-australia-breitbart-newspunch/,Misleading,"Breitbart, NewsPunch, Paul Joseph Watson, Sean Adl-Tabatabai, Thomas D. Williams, 2020-01-05","the bushfires [in Australia] were caused by arsonists and a series of lightning strikes, not 'climate change'",,"Misrepresents a complex reality: While authorities in Australia are investigating the source of some of the bushfires, this does not preclude other factors from being important for some aspects of these fires. For instance, the magnitude of wildfires is controlled primarily by the conditions of the fuels. Unsupported: The claim that these fires are due to high arson activity is not supported by evidence. Less than one percent of the land burnt in New South Wales and Victoria has been attributed to arson so far.","The important contribution of climate change to fires is not in starting fires (although increases in lightning are possible) but in making fuels drier. The current fires in Australia are not so extreme because fires were sparked, but because 2019 was the hottest and driest year on record, with dry and windy weather patterns in place as the fires burned. The source of ignition for each fire is not relevant to understanding whether climate change contributed to their extent and intensity.","Authorities in Australia have confirmed the bushfires were caused by arsonists and a series of lightning strikes, not 'climate change' as many activists have claimed.","1- Mariani et al (2018) Climate Change Amplifications of Climate‐Fire Teleconnections in the Southern Hemisphere, Geophysical Research Letters 2- Di Virgilio et al (2019) Climate Change Increases the Potential for Extreme Wildfires, Geophysical Research Letters 3- Cai et al (2013) Projected response of the Indian Ocean Dipole to greenhouse warming, Nature Geoscience 4- Cai et al (2009) Positive Indian Ocean Dipole events precondition southeast Australia bushfires, Geophysical Research Letters 5- Dowdy (2018) Climatological Variability of Fire Weather in Australia, Journal of Applied Meteorology and Climatology UPDATE (9 Jan. 2020): The NewsPunch article has been corrected. It now states that “An earlier version of this article incorrectly stated that climate change did not contribute to the bushfires in Australia. While authorities in Australia have blamed arsonists for starting the fires, this does not mean climate change didn’t play a role in making them more extreme”. (20 Jan. 2020): We have added information about the estimated surface burnt that can be tied to arson according to Australian state officials as well as more background information about the global relationship between fires and climate change provided by Dr Matthew Jones.","Dozens of outlets, blogs and social media users have made the claim that climate change has no influence on the bushfires currently burning record areas in Australia because authorities are investigating who or what started some of these fires, suspecting some fires were ignited by people and many more by lightning. This flawed reasoning misunderstands that fires are exacerbated by hot and dry conditions and Australia is currently facing a severe drought amidst increasing temperatures. The temperature trend is linked to human-caused climate change and contributes to drier fuel and soils by increasing evaporation. While conditions were exceptionally warm and dry in southern Australia, there is no evidence to suggest that the current season has seen a higher level of arson, although some bushfires are indeed typically caused by humans (intentionally or not). ABC News queried state officials and found that “Only about 1 per cent of the land burnt in [New South Wales] this bushfire season can be officially attributed to arson, and it is even less in Victoria.” South Australia reported no suspicious fires, and the Queensland Fire and Emergency Services said 3 per cent of the bushfires in the state this season were deliberately lit. In Tasmania, however, the story reports that “21,000 of the 35,000 hectares burnt is a result of deliberately lit fires”. Claims that 183 (or more) arsonists were arrested in connection with the fires have circulated on social media, but multiple fact-checkers have found this to be inaccurate. The number 183 comes from a release from the New South Wales police, describing the number of fire-related legal actions taken between early November and early January. They explain that legal action “ranges from cautions through to criminal charges”, and that only 24 of these relate to deliberately set fires. The others are citations for failing to abide by fire bans, including 47 actions “for allegedly discarding a lighted cigarette or match on land”. A separate fact check from ABC News provides additional context, noting that the number of bushfire arson offenses in 2019 was below the average of the last decade in both Victoria and New South Wales. Regarding the potential influence of climate change so far, the Australian Bureau of Meteorology’s website indicates that “Climate change is influencing the frequency and severity of dangerous bushfire conditions in Australia and other regions of the world, including through influencing temperature, environmental moisture, weather patterns and fuel conditions”. A recent study has identified a “clear trend toward more dangerous [fire] conditions during spring and summer in southern Australia”1. Another study found that “climate change increases the potential for extreme wildfires”2. While a precise attribution study will be needed to quantify the influence of climate change on this specific series of fires in Australia, the above claim prematurely rules out climate change as a factor in the severity of these fires. Conversely, one should not conclude that climate change is the only factor influencing bushfires (you can read more on this at Carbon Brief). For instance, a study has shown that drought and bushfire in Australia are linked to temperature fluctuations in the Indian Ocean3 known as the Indian Ocean Dipole (IOD). Positive IOD events typically result in below average winter-spring rainfall over southern and central Australia, and are often associated with more severe bushfire conditions4, as was the case this season. Stefan Doerr Professor, Swansea University: This statement misleadingly suggests that many activists argue that the fires are “ignited” due to climate change. The “authorities” are focusing here on the ignitions, which are typically lighting, arson, or accidental in each fire season in Australia. (That noted, increases in atmospheric temperature do increase lightning frequency and hence wildfire probability1.) What activists are concerned about is not the “ignitions” per se; there will always be potential sources of ignitions. What most activists (and many scientists) are concerned about is that the extreme intensity and extent of the fires in this fire season are a result of the environmental impact of climate change. The combination of such widespread temperature maxima not recorded before combined with very dry live and dead vegetation following a long and severe drought has allowed the ignitions (be it arson, lightning, or accidental) to conflagrate to fires covering an unprecedented geographic range in recorded history. For example, in New South Wales alone the extent of the area burned in a single fire season is unprecedented in recorded history and so is the severity of the drought in this state. The increased likelihood of extreme drought and high temperatures occurring is consistent with observed recent trends and predictions of the impact of climate change in this region5. [This article concludes: “there is a clear trend toward more dangerous conditions during spring and summer in southern Australia, including increased frequency and magnitude of extremes, as well as indicating an earlier start to the fire season. Changes in fire weather conditions are attributable at least in part to anthropogenic climate change, including in relation to increasing temperatures.” Matthew Jones Senior Research Associate, University of East Anglia: [This comment was provided on behalf of the authors of this article at ScienceBrief, which reviewed the scientific literature on the relationship between climate change and wildfires, globally.] Our review focussed on fire weather, periods of hot, dry and low humidity conditions, exacerbated by strong winds, and described evidence of these types of weather occurring increasingly often in recent decades. We found strong consensus that climate change is increasing the frequency and severity of fire weather. The impact of anthropogenic climate change on fire weather has emerged above natural variability in 22% of the global burnable land area, including Amazonia, western US and Canada, southern Europe and Scandinavia. For Australia, increases in fire weather extremes and extensions of fire weather season have been observed, although attribution studies are not yet able to formally identify anthropogenic climate change beyond the range of natural variability. This is due to the particularly high variability in fire weather in Australia, driven by El Niño Southern Oscillation (ENSO) and other large-scale weather patterns. This is an active area of research and studies including data from the 2019-20 fire season have already commenced. Multiple factors affect wildfire activity and so fire weather does not translate directly to burned area. Burned area has reduced globally over the past two decades, chiefly in regions where savannah has been converted to agriculture. The situation is different in forests, where human incursion has increased burned area and acted as a dual upwards pressure, alongside climate change, on fire risk."
https://science.feedback.org/review/volcanic-co2-emissions-are-known-to-be-much-smaller-than-human-caused-emissions-james-edward-kamis/,Inaccurate,"Principia Scientific, James Edward Kamis, 2018-11-07",Discovery Of Massive Volcanic CO2 Emissions Discredits Global Warming Theory,,Factually Inaccurate: Scientists have established that volcanic emissions are small compared to human-caused emissions.,"This article claims that volcanic sources of carbon dioxide are poorly understood and could well be the cause of modern global warming, rather than human activities. In reality, current annual human-caused emissions are at least 100 times greater than all volcanic emissions.",Discovery Of Massive Volcanic CO2 Emissions Discredits Global Warming Theory [...] All indications are that Earth is currently experiencing another period of strong volcanic activity which is acting to infuse CO2 into our atmosphere thereby challenging the validity of the global warming theory.,,"Carbon dioxide is released into the atmosphere by volcanic eruptions—as well as by passive venting around volcanoes that are not erupting. The amount of CO2 emitted varies from one volcanic feature to another, and varies with time, which makes quantifying global emissions a challenge. However, there are multiple ways of constraining their contribution. The most recent estimate1 puts total global emissions from all volcanic activity at approximately 280 million to 360 million metric tons of CO2 per year. Of this, active eruptions only account for about 2 million metric tons per year. Additionally, there is no evidence that volcanic activity has increased over the last century, while atmospheric CO2 has increased significantly. Human-caused CO2 emissions are much larger than this estimate. Current emissions from fossil fuel burning, industrial processes, and land use change (like deforestation) equal about 39 billion metric tons per year2—at least 100 times greater than the amount released by all volcanic activity, let alone eruptions. Prior to human-caused emissions, Earth’s carbon cycle was in balance. The amount of CO2 released by things like volcanoes, wildfires, and respiration by living things was equal to the amount of atmospheric CO2 taken up by processes like bedrock weathering and photosynthesis. Human-caused emissions are not matched by a human-caused process of CO2 uptake, so this net addition is responsible for the observed increase in atmospheric CO2 since the Industrial Revolution. In addition to these accounting methods for estimating the factors related to the atmospheric CO2 concentration, the source of the CO2 added to the atmosphere can also be determined from the isotopes of carbon in the air. Contrary to the claim in the article, the carbon atoms in volcanic CO2 do have a different isotope ratio than the carbon atoms in fossil fuel CO2. In fact, the very source the article links to support its claim actually explains this. The measured change in atmospheric carbon-14, carbon-13, and carbon-12 shows that the CO2 added to the atmosphere has come from fossil fuel burning and deforestation—not volcanoes or other sources3. 1- Werner et al (2019) Carbon Dioxide Emissions from Subaerial Volcanic Regions (in Deep Carbon, Past to Present) 2- Le Quéré et al (2018) Global Carbon Budget 2018, Earth System Science Data 3- Rubino et al (2013) A revised 1000 year atmospheric δ13C‐CO2 record from Law Dome and South Pole, Antarctica, Journal of Geophysical Research: Atmospheres Tobias Fischer Professor, University of New Mexico: The contribution of volcanoes to the global carbon dioxide (CO2) emissions budget is small1-16 compared to the emission from burning of fossil fuels17. In detail, the contribution of volcanic eruptions can be illustrated by considering recent, well-studied large eruptions, such as the 2014 Holhuraun eruption in Iceland. The massive Holhuraun eruption emitted a cumulative amount of 9,330 kilotons of CO2 (or 9.3 x1012 g CO2)18. The eruption of Etna Volcano in Italy in the year 2006 emitted a cumulative CO2 amount of 644 kilotons (or 0.644 x 1012 g CO2). Another recent and massive eruption was the 2010 Eyjaflallajokul eruption in Iceland that emitted a cumulative amount of CO2 of 5,130 kilotons (or 5.1 x 1012 g CO2)18. While these eruptions have significantly affected local air travel and disrupted the daily lives of the population living in the region, the amount of CO2 emitted is dwarfed by the emissions resulting from human activities. The burning of fossil fuels and production of cement has released 36.3 gigatons of CO2 (or 36,300 x 1012 g CO2) into the atmosphere in 201517. Therefore, the largest CO2 emitting eruption in the past 15 years (Holhuraun in 2014) produced only about 0.026% of the yearly anthropogenic emissions. Indeed, we would need to have about 3,890 such massive eruptions like Holhuraun in one year to produce the equivalent of CO2 emitted due to fossil fuel burning and cement production. However, such large CO2 emitting eruptions are rare and the Holuhraun 2014 eruption is unique in the past 15 years18. The total CO2 emissions for volcanic eruptions for the time frame from 2005 to 2018 was 26.9 megatons (or 26.0 x 1012 g CO2) and, therefore, in an average year only about 2,070 kilotons of CO2 (or 2.0 x 1012 g) are produced from volcanic eruptions18. This means that, during a typical year, volcanic eruptions contribute only about 0.006% of the global anthropogenic CO2 flux. The average CO2 emission of a person living in the USA is about 16 tons of CO2 per year17. Therefore, in any given year volcanic eruptions produce only about as much CO2 as 130,000 Americans, or less than the population of Wyoming—the state with the lowest population in the US. 1- Aiuppa et al (2019) CO2 flux emissions from the Earth’s most actively degassing volcanoes, 2005–2015, Scientific Reports 2- Allard (1992) Global Emissions of helium-3 by subareal volcanism, Geophysical Research Letters 3- Brantley and Koepenick (1995) Measured carbon dioxide emissions from Oldoinyo Lengai and the skewed distribution of passive volcanic fluxes, Geology 4- Burton et al (2013) Deep carbon emissions from volcanoes, Reviews in Mineralogy and Geochemistry: Carbon in Earth 5- Fischer (2008) Volatile fluxes (H2O, CO2, N2, HCl, HF) from arc volcanoes , Geochemical Journal 6- Gerlach (1991) Present-day CO2 emissions from volcanoes, EOS Transactions 7- Hilton et al (2002) Noble gases in subduction zones and volatile recycling, MSA Special Volume: Noble Gases in Geochemistry and Cosmochemistry 8- Kerrick (2001) Present and past nonanthropogenic CO2 degassing from the solid earth, Reviews of Geophysics 9- Le Guern (1982) Les debits de CO2 et de SO2 volcaniques dans l’atmosphere. Translated title: Discharges of volcanic CO2 and SO2 in the atmosphere, Bulletin of Volcanology 10- Williams et al (1992) Global carbon dioxide emission to the atmosphere by volcanoes, Geochimica et Cosmochimica Acta 11- Marty et al (1989) Helium isotopes and CO2 in volcanic gases of Japan, Chemical Geology 12- Marty and LeCloarec (1992) Helium-3 and CO2 fluxes from subaereal volcanoes estimated from Polonium-20 emissions, Journal of Volcanology and Geothermal Research 13- Marty and Tolstikhin (1998) CO2 fluxes from mid-ocean ridges, arcs and plumes, Chemical Geology 14- Moerner and G. Etiope (2002) Carbon degassing from the lithosphere, Global and Planetary Change 15- Sano and Williams (1996) Fluxes of mantle and subducted carbon along convergent plate boundaries, Geophysical Research Letters 16- Shinohara (2013) Volatile fluxes from subduction zone volcanoes: insights from a detailed evaluation of the fluxes from volcanoes in Japan, Journal of Volcanology and Geothermal Research 17- Le Quéré et al (2016), Global Carbon Budget 2016, Earth System Science Data 18- Werner et al (2019) Carbon Dioxide Emissions from Subaerial Volcanic Regions (in Deep Carbon, Past to Present)"
https://science.feedback.org/review/article-falsely-attributes-invented-quotes-to-james-hansen-dmitry-baxter/,Inaccurate,"NewsPunch, Principia Scientific, Your News Wire, Baxter Dmitry, 2018-07-08",Father of Global Warming’ Scientist Finally Admits Theory Is Wrong,,"Factually Inaccurate: The headline and article attribute false quotes to scientist James Hansen, who never said them. Misleading: The article fails to accurately explain the characteristics of the greenhouse gas scenarios used in Hansen's 1988 model simulations, or how those scenarios compare to the emissions that actually occurred since then.","This article falsely attributes quotes to NASA climate scientist James Hansen, when these statements are actually the opinions of others. It also misrepresents 1988 projections of global warming produced by Hansen and his colleagues, which were, in reality, accurate.","‘Father of Global Warming’ Scientist Finally Admits Theory Is Wrong [...] a new study that compares real-world data to the original Scenario B model — finding no correlation — has received Hansen’s backing, with the “Father of global warming” admitting he is “devastated” by the way his data has been used by climate alarmists.",,"This article, republished from NewsPunch (formerly Your News Wire) by Principia Scientific, quotes a Western Journal commentary that itself quotes from a separate blog post and a Wall Street Journal op-ed. Along the way, claims made by other people were turned into quotes attributed to scientist James Hansen—but he never said these things. Versions of this 2018 article have more recently been widely shared on Facebook. The article refers to a “study” analyzing Hansen’s 1988 model simulations that projected future warming, but the source is, in fact, a blog post and Wall Street Journal op-ed rather than a peer-reviewed study. Those sources claim that the 1988 model simulations projected more warming than actually occurred, but they failed to accurately account for the greenhouse gas emission scenarios that were used. Models must use scenarios of future greenhouse gas emissions to project future warming trends, because climate scientists have no way to predict future human actions. In order to evaluate the physics of a climate model, therefore, one must account for any differences between the greenhouse gas emissions scenario used and the emissions that have actually occurred. Hansen’s 1988 simulations used three scenarios: A, B, and C. Careful analysis, as in this Real Climate post shows that Scenario B was closest to the emissions that have occurred, but its emissions were slightly higher than the real world. If Scenario B’s emissions are adjusted to match the real world, the predicted temperature trend does match observed temperatures. Source: Real Climate The claim published by NewsPunch and Principia Scientific is that there is “no correlation” between the model projection and real-world temperatures, but this is false. The article expands on this by claiming that the inaccurate analysis “has received Hansen’s backing”, and that Hansen admitted he was “‘devastated’ by the way his data has been used by climate alarmists”. No source is provided for these statements. The headline of the Western Journal commentary claimed “Father of Global Warming’s Theory Devastated by Actual Data”, but there is no quote in which Hansen supports this claim. The only Hansen quote in any of these articles is taken from an article published by the Associated Press, which was titled “James Hansen wishes he wasn’t so right about global warming”. In this article, Hansen says, “I don’t want to be right in that sense,” in the context of his accurate projections of the warming that has now occurred. So the other statement attributed to Hansen by the NewsPunch and Principia Scientific article—that he “finally admits theory is wrong”—is also invented, as Hansen did not say this."
https://science.feedback.org/review/ice-cube-meme-misrepresents-physics-of-sea-level-rise-to-claim-melting-ice-has-no-effect/,Incorrect,"Facebook, Anonymous, 2019-12-11","[Photo] A little science lesson for the #idiots at the global warming conference. Ice berg melts, ocean level remains the same.",,"Flawed Reasoning: Floating ice that melts does not appreciably raise the water level, but melting land ice—or placing ice cubes in a glass—does.",Global sea level rise is caused primarily by two processes: (1) the expansion of seawater as its temperature increases and (2) the melting of glacial ice on land. It is well known that the melting of floating ice does not play a role.,"A little science lesson for the #idiots at the global warming conference. Ice berg melts, ocean level remains the same.",,"This meme, which has spread widely on Facebook, implies that the science of human-caused global sea level rise is based on the faulty assumption that floating ice raises sea level as it melts. However, a critical step is missing in this set of “before-and-after” photos: the water level before the ice cubes were placed in the measuring cup. The ice on planet Earth—part of what is termed the “cryosphere“—includes sea ice as well as glacial land ice. Sea ice is frozen seawater floating at the surface, not unlike the ice that covers a lake or river in colder winter climates. As such, the freezing and melting of sea ice does not have a significant effect on sea level, though the loss of polar sea ice does have profound impacts on local ecosystems and the Earth’s climate system. But on land, glaciers high in mountains around the world or making up part of the great ice sheets of Greenland and Antarctica, do raise sea level when they melt and flow into the ocean. Some glaciers end on land, with meltwater flowing down rivers to reach the ocean. Other glaciers slide into the ocean directly, calving off large blocks called “icebergs” that drift away as they melt. https://science.feedback.org/wp-content/uploads/2019/12/IMBIE-2-AIS-GrIS.mp4 Source: Ice Sheet Mass Balance Inter-comparison Exercise (IMBIE) Project The melting of an iceberg does not raise sea level significantly, because it is already displacing that volume as it floats. (There is, however, a small additional contribution from the dilution of salty seawater with fresh melt from the iceberg. This adds 2-3% to the volume of displaced seawater.1) But as the land-based portions of glaciers shrink, more and more icebergs and meltwater are added to the ocean, raising sea level. Greenland, for example, lost around 3,800 billion tonnes of ice between 1992 and 2018, while Antarctica lost about 2,700 billion tonnes between 1992 and 2017, together raising global sea level by about 18 millimeters over that timespan2,3. There is also one more process that is a primary contributor to sea level rise: thermal expansion. Like other fluids, seawater expands as its temperature increases. This means that as the oceans warm, their volume expands enough to raise sea level measurably. Satellite measured sea level rise from 1993 through July 2019. 1- Jenkins and Holland (2007) Melting of floating ice and sea level rise, Geophysical Research Letters 2- Shepherd et al (2018) Mass balance of the Antarctic Ice Sheet from 1992 to 2017, Nature 3- Shepherd et al (2019) Mass balance of the Greenland Ice Sheet from 1992 to 2018, Nature UPDATES: 18 Dec. 2019: Two sentences were added to clarify the effect of salinity after Prof. Andrew Shepherd reviewed this post for accuracy."
https://science.feedback.org/review/1977-coming-ice-age-time-magazine-cover-is-a-fake/,Inaccurate,"Facebook, Anonymous, 2019-12-11",When the exact same group of 'experts' who claimed it was global cooling in 1977 now claim it's global warming you can easily see why I am skeptical,,Factually Inaccurate: The 1977 Time magazine cover shown in this image is fake and it is not true that climate science predicted global cooling in the 1970s.,"This meme utilizes a widely circulated fake image purporting to show a 1977 Time magazine story titled ""How To Survive The Coming Ice Age"". The cover is actually from 2007, for a story titled ""The Global Warming Survival Guide"". While a claim of global cooling did appear a couple times in the 1970s in popular media, that did not reflect the understanding of climate scientists at the time.",When the exact same group of 'experts' who claimed it was global cooling in 1977 now claim it's global warming you can easily see why I am skeptical,,"The images included as part of this meme. There are many versions of memes like this one (which is currently being shared widely on Facebook) seeking to disregard the conclusions of climate science on the false premise that the issue of human-caused global warming replaced warnings of global cooling from the 1970s. Most of these memes include this doctored image labeled as a 1977 Time magazine cover for an article titled “How To Survive The Coming Ice Age”. There was no such article or cover in 1977. As Time itself explains here, the penguin cover actually comes from 2007, and an article titled “The Global Warming Survival Guide”. Source: Time The broader claim about climate science also does not match the reality of the 1970s. Two real magazine stories are sometimes cited: a 1974 Time article titled “Another Ice Age?” and a 1975 Newsweek article titled “The Cooling World”. But as the author of that Newsweek story noted in a 2014 post, these didn’t accurately reflect the whole of 1970s climate science. Scientists in the 1970s were studying rising aerosol pollution—tiny particles produced by things like coal-burning plants without pollution controls—that reflects incoming sunlight. Using early climate models, they were working to quantify the cooling influence of this type of pollution. Given that aerosol pollution was rapidly increasing at the time, some studies even warned that its cooling effect could grow if that behavior continued. It did not, however, as pollution controls were introduced. And those same climate models were being used to quantify the warming caused by human-caused greenhouse gas emissions, which was seen as the dominant trend.1 At the same time, scientists were recovering the first ice core records of 100,000-year-long glacial (or “ice age”) periods, enabling them to understand how slow-changing cycles in Earth’s orbit triggered those events in the past. Since those cycles play out over tens of thousands of years, this information did not have direct implications for modern climate change. However, this research was conflated with near-term climate research by some media stories. While the scientific understanding of human-caused global warming progressed significantly in the 1970s, 1980s, and 1990s, the connection between fossil fuel burning and global warming can be traced back as far as the 1890s. Research published in the 1970s shows that this connection continued to be studied. A 1975 paper published in the journal Science2, for example, projected continued warming totalling 0.8°C by 2000—only slightly more than actually occurred. And a prominent US National Academy of Sciences report published in 19793 estimated the warming power of CO2 at 3°C (±1.5°C) for a doubling of the concentration, a number that is still consistent with current scientific understanding. 1- Peterson et al (2008) The Myth of the 1970s Global Cooling Scientific Consensus, Bulletin of the American Meteorological Society 2- Broecker (1975) Climatic Change: Are We on the Brink of a Pronounced Global Warming?, Science 3- National Research Council (1979) Carbon Dioxide and Climate: A Scientific Assessment [This comment is taken from a previous review of similar claim.] From the 1940s to the 1970s, the global surface temperature decreased very slightly. This probably occurred because over that time period the cooling effect from human produced aerosols was slightly larger than the warming effect from human produced greenhouse gasses. A minority of scientists predicted that the cooling effect from increasing aerosols would continue to outweigh the warming effect from increasing greenhouse gasses and that the climate would continue to cool. This idea received some public attention when Time magazine published an article titled “Another Ice Age?” in 1974 (the cover of Time shown [above] is a fake). Regardless, this article did not represent the views of the majority of the scientific literature at the time1. For example, a 1975 paper, published by Wallace Broecker2 contained the following abstract: “If man-made dust is unimportant as a major cause of climatic change, then a strong case can be made that the present cooling trend will, within a decade or so, give way to a pronounced warming induced by carbon dioxide. By analogy with similar events in the past, the natural climatic cooling which, since 1940, has more than compensated for the carbon dioxide effect, will soon bottom out. Once this happens, the exponential rise in the atmospheric carbon dioxide content will tend to become a significant factor and by early in the next century will have driven the mean planetary temperature beyond the limits experienced during the last 1000 years.” This prediction turned out to be remarkably accurate. 1- Peterson et al (2008) The myth of the 1970s global cooling scientific consensus, Bulletin of the American Meteorological Society 2- Broecker (1975) Climatic Change: Are we on the brink of a pronounced global warming?, Science"
https://science.feedback.org/review/abc-article-effectively-illustrates-important-climate-trends-for-australian-readers-tim-leslie-joshua-byrd-nathan-hoad/,1.7,"Australian Broadcasting Corporation, by Joshua Byrd, Nathan Hoad, Tim Leslie, on 2019-12-05.",,"""See how global warming has changed the world since your childhood""",,,,,"This interactive article at ABC allows readers to enter their year of birth and see how temperatures have changed in their lifetime in relatable ways. It also describes projections for future change in Australia, including extremes like heatwaves and bushfires. The article highlights the difference between projections with aggressive emissions reductions and those where emissions continue to increase. Scientists who reviewed this article found that it presents accurate information on these topics and communicates that information effectively.See all the scientists’ annotations in context. You can also install the Hypothesis browser extension to read the scientists’ annotations in context.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Mark Richardson Research Associate, Colorado State University/NASA JPL: This is a sound article with a solid scientific basis, and the most important sources are provided. I judge its accuracy as “high” rather than “very high” because some of the difficulties and uncertainties are glossed over. For example, looking at short periods in a single country can be difficult, and changes in biological systems like coral reefs are very hard to project. Overall I believe the authors have done a good job at accurately distilling the research on a complex topic. Amber Kerr Researcher, Agricultural Sustainability Institute, University of California, Davis: This is one of the best pieces I’ve seen on how climate change will impact a particular country within an individual’s lifetime. The projections they used for temperature increase under mitigation and non-mitigation scenarios are, unfortunately, quite accurate. (We all wish the news weren’t so bad, but it is.) The authors correctly explain how even moderate climate change causes a drastic increase in the number of extremely hot days, which are defined either as days above a certain temperature or as days where the temperature exceeds a certain percentile (usually 99th) of historical data. The authors also correctly explain that the effects of climate change on other natural disasters (such as droughts, floods, and bushfires) are much harder to predict and are not always in a single direction. I found no inaccurate or misleading data in this article. The authors did an excellent job explaining climate variability, climate trends, and future warming in a way that was both scientifically accurate and emotionally compelling. Andrew King Research fellow, University of Melbourne: This article is exceptionally good in delivering accurate information in an engaging way. There are many useful statements made about the effects of climate change on extreme weather globally and in Australia and these have been backed up by links to relevant peer-reviewed literature. Andreas Klocker Physical Oceanographer, University of Tasmania: This is one of the most well-written articles explaining climate extremes which I have read so far. It explains clearly the difference between changes in global mean temperature and extreme events, a topic which can be very confusing to non-scientists. This article is very credible, with references throughout the article backing up the statements made. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from the article; comments are from the reviewers (and are lightly edited for clarity). Small increases in average temperature translate to big increases in the number of extremely hot days, and those hot days have a big impact. Andrew King Research fellow, University of Melbourne: This article uses relevant information on extremes to help show readers the impact of climate change through information less abstract than the global temperature. When the Emergency Leaders for Climate Action approached the Federal Government in April they were drawing on decades of data showing that fire conditions are getting worse. Andrew King Research fellow, University of Melbourne: The Forest Fire Danger Index (FFDI) does indeed point to worsening conditions. It’s worth noting though that it’s very hard to characterise bushfire risk using a single index and the FFDI wasn’t designed with a changing climate in mind. In general, there is a great deal more confidence in projections for extreme weather like heatwaves than there is for bushfire weather. So it’s hotter, and there’s a greater risk of bushfires, but has Australia been getting drier? I mean, there were droughts when you were a kid, right? Well Australia hasn’t been getting drier overall, but where the rain is falling is changing and that is already having a big impact. Andrew King Research fellow, University of Melbourne: This is a great way of communicating a more nuanced change in the climate. As the temperature has increased, so has the ability of scientists to determine whether specific events are linked to climate change. They can now model how likely a specific event would be to occur under historical conditions, compared to the record temperatures we’re experiencing. Andrew King Research fellow, University of Melbourne: This is an accurate description of event attribution. And by the time they turn 50, if globally we had managed to halt our emissions quickly back in the 2020s, the temperature will have begun to stabilise. We’ll still be facing extreme heat, but at a far more manageable level than if we’d done nothing to halt climate change. Andrew King Research fellow, University of Melbourne: The whole section on future climate projections under different scenarios is superbly explained. The information is well delivered and backed up by relevant peer-reviewed literature. UPDATES: 11 December 2019: A comment from Andreas Klocker was received and added after the initial publication."
https://science.feedback.org/review/ian-plimer-op-ed-in-the-australian-again-presents-long-list-of-false-claims-about-climate/,-2,"The Australian, by Ian Plimer, on 2019-11-22.",,"""Let’s not pollute minds with carbon fears""",,,,,"This op-ed in The Australian by Ian Plimer, titled “Let’s not pollute minds with carbon fears”, makes many claims: that polar ice is not melting, that human-caused CO2 emissions can’t cause climate change, that all life on Earth would die if CO2 levels dropped to half of current levels, and so on. None of these things are true. As was the case with three other op-eds written by Plimer that we evaluated previously, reviewers unanimously rated the scientific credibility of this article “very low”. In their comments below, the scientists identify a large number of inaccurate or incorrect statements about the way Earth’s climate system works, how climate has changed during Earth’s history, and what we know about the impacts of continued climate change.See all the scientists’ annotations in context. You can also install the Hypothesis browser extension to read the scientists’ annotations in context. REVIEWERS’ OVERALL FEEDBACK: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Mark Richardson Research Associate, Colorado State University/NASA JPL: This article will mislead readers. It uses nonsense logic, is clueless about the science, and says things which are wrong. Some of these false statements have been obviously wrong for years. One example is claiming “[i]t has never been shown that human emissions of carbon dioxide drive global warming.” This shows cluelessness about decades of important research. Direct measurements1 show that more atmospheric CO2 is causing enough heating to explain the observed warming, and we know that the CO2 rise is caused by us2. Those studies are two of hundreds that have built the overwhelming case that human CO2 emissions are now driving global warming. Climate models are computer programs that crunch equations describing the laws of physics, and they also calculate that rising CO2 is driving the observed warming. They include changes in solar activity, and a study from 20063 found that climate models calculate strong effects of clouds on global warming—they could either amplify or slow CO2-driven warming. It is completely fake of Plimer’s article to say that “[t]he role of the sun and clouds was not considered important by modellers”. Since our CO2 emissions are the main driver of recent warming, we expect a correlation between these emissions and global temperature. By plotting temperature against emissions and using standard statistics we can calculate the correlation, this example is for 1959—2014 (the correlation gets stronger if you use other datasets which extend to 2018). The data show a strong correlation since 1959, with temperatures being higher when cumulative human emissions are higher. It is simple for anyone with basic maths training and an internet connection to check this, and it is false to claim that “in our lifetime, there has been no correlation between carbon dioxide emissions and temperature” as the Australian’s article does. Correlation doesn’t prove that one causes the other but this is a good example of how the Australian’s article is inaccurate, relies on falsehoods, and will mislead readers. 1- Feldman et al (2015) Observational determination of surface radiative forcing by CO2 from 2000 to 2010, Nature 2- Richardson (2013) Comment on “The phase relation between atmospheric carbon dioxide and global temperature” by Humlum, Stordahl and Solheim, Global and Planetary Change 3- Soden and Held (2006) An Assessment of Climate Feedbacks in Coupled Ocean–Atmosphere Models, Journal of Climate Peter Landschützer Group Leader, Max Planck Institute for Meteorology: The entire article is just a list of inaccurate and false claims made by the author, contradicting the best scientific evidence (e.g. from measurement records) we have today. Twila Moon Research Scientist, University of Colorado, Boulder: This article is a laundry list of falsehoods, misleading examples, and facts taken out of context. It is appalling that such a blatantly false article can be published in any credible news outlet today. Martin Singh Postdoctoral Research fellow, Harvard University: This article is a mixture of misdirection, misleading claims, and outright falsehoods. The author attempts to paint a picture of current climate change as simply a continuation of natural changes that have occurred in the past. But this neglects the clear evidence that climate change over the last two centuries has been shown to be largely man-made, that it is much more rapid that anything we have seen in the last two thousand years if not longer, and that it is occurring in the context of a globe with more than 7 billion human inhabitants. The author makes incorrect claims about climate models failing (against what metric?), that climate change cannot be driven by a trace gas (how did we get out of the ice covered state called “snowball Earth”, not to mention the role of carbon dioxide in many examples of climate change over Earth’s history?), that carbon dioxide concentrations were higher at the beginning of the last ice age (they weren’t). Interspersed with these falsehoods are various long interludes about how carbon dioxide is essential for life and helps plants grow. This doesn’t change the fact that the planet is getting warmer, and it doesn’t change the fact that most studies expect agricultural yields to suffer as the world becomes increasingly warmer in spite of the carbon dioxide fertilisation effect. The facts are that human activity has increased greenhouse gas concentrations in the atmosphere to levels not seen for close to a million years. Multiple lines of evidence from observations, modelling, and theory shows us that this increase in greenhouse gas concentrations leads to warming of the globe. As this warming continues, it will lead to sea-level rise, changes to rainfall patterns, and, for higher levels of warming, it may render parts of the world essentially uninhabitable for humans without air conditioning. To deny this strong and robust evidence is irresponsible in the extreme. Katrin Meissner Professor, University of New South Wales: Virtually every single scientific statement in this article is either misleading or downright wrong. Some statements are almost amusing, such as, “there are no carbon emissions. If there were, we could not see because most carbon is black”. The Australian should be ashamed of itself. What next? An opinion piece on the flat Earth theory? Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: This article is an absurd collection of non-sequiturs, distortions, and outright falsehoods that have been thoroughly debunked over the past decade. This is obvious propaganda from someone with close financial ties to the fossil fuel industry. Dan Jones Physical Oceanographer, British Antarctic Survey: This article contains a large number of inaccurate and misleading statements. It is not grounded in our understanding of the Earth system. Mark Eakin Scientist, Coordinator of NOAA’s Coral Reef Watch, National Oceanic and Atmospheric Administration: There are a few points he makes that are true. The other 95% are not. Even those that are true are used to mislead the reader. Alexis Berg Research Associate, Harvard University: Just like previous pieces by the same author (some of which were already addressed by Climate Feedback), this piece is an unorganized collection of the same old misleading “arguments” from climate change deniers that have been addressed thousands of times before, of which there are too many to summarize here. It is frankly appalling that any newspaper that would like to retain some credibility would continue to publish such pieces. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Annotations: The statements quoted below are from the article; comments are from the reviewers (and are lightly edited for clarity). Pollution by plastics, sulphur and nitrogen gases, particulates and chemicals occurs in developing countries. That’s real pollution. Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: Strangely, Ian Plimer uses the “no true Scotsman” logical fallacy here to imply that because these forms of pollution are an issue, carbon pollution is somehow insignificant.There are no carbon emissions Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: So absurd as to almost defy comment. Humans are burning coal, petroleum products, and natural gas. Very basic chemistry tells us that a bi-product of this is the creation of carbon dioxide gas. Peter Landschützer Group Leader, Max Planck Institute for Meteorology: There are plenty of reliable resources (such as the United Nations Inventory Submissions) that readers can check to find out that there are CO2 emissions. Furthermore, in the last paragraph the author states himself that there are emissions (using China as an example). If there were [carbon emissions], we could not see because most carbon is black. Martin Singh Postdoctoral Research fellow, Harvard University: Carbon dioxide, the main gas that makes up “carbon emissions”, is colourless and odourless. Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: Most carbon is not black. Black carbon itself results from incomplete combustion of carbon-based fuel such as fossil fuels or biomass. Ironically, it is also a significant contributor to global warming due to its ability to reduce the albedo of ice-covered areas. Great Barrier Reef bleaching that has really been occurring for hundreds of years Mark Eakin Scientist, Coordinator of NOAA’s Coral Reef Watch, National Oceanic and Atmospheric Administration: The recent paper that made this claim was some of the worst science to be published in a reputable journal in many years. The authors of all of the datasets they misused wrote the editors calling for the paper to be retracted but the journal decided not to do so. Instead, a rebuttal paper1 provides all the reasons why that paper is wrong and should have been retracted. 1- Hoegh-Guldberg et al (2019) Commentary: Reconstructing Four Centuries of Temperature-Induced Coral Bleaching on the Great Barrier Reef, Frontiers in Marine Science Katrin Meissner Professor, University of New South Wales: The reef’s overall habitat status has been downgraded to “poor” for the first time in this year’s Great Barrier Outlook Report, citing hundreds of peer-reviewed papers. The report considers the condition and outlook of coral reef habitats specifically to be very poor in the northern two-thirds. The assessment clearly states the greatest threat to the Great Barrier Reef’s long-term outlook is climate change. fraudulent changing of past weather records Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: A lie, referring to the homogenisation of weather records to remove biases. This is nothing more than a conspiracy theory. For more information on this topic, read our review “NASA did not create global warming by manipulating data”the ignoring of data that shows Pacific islands and the Maldives are growing rather than being inundated Katrin Meissner Professor, University of New South Wales: The dynamics of shorelines of low-lying Pacific Islands are complicated and influenced by many local factors. Climate change and associated sea-level change are the underlying trend that will “win” over long time scales. There are many wiggles and local anomalies that, if taken out of context and analysed over short timescales, might hide the overall trend. For more information on this topic, read our review “Analysis of ‘About Those Non-Disappearing Pacific Islands’”unsubstantiated claims polar ice is melting Alexis Berg Research Associate, Harvard University: What’s unsubstantiated about polar ice melting? We can literally see Arctic sea ice decrease. Regarding ice caps, there are plenty of studies with different methodologies indicating Greenland and at least parts of Antarctica are losing ice1,2. 1- Shepherd et al (2019) Trends in Antarctic Ice Sheet Elevation and Mass, Geophysical Research Letters 2- Groh et al (2019) Evaluating GRACE Mass Change Time Series for the Antarctic and Greenland Ice Sheet—Methods and Results, Geosciences Katrin Meissner Professor, University of New South Wales: This is wrong. Satellite measurements show a decline in Greenland and Antarctica ice mass balances. We’ve had reefs on planet Earth for 3500 million years. They came and went many times. Mark Eakin Scientist, Coordinator of NOAA’s Coral Reef Watch, National Oceanic and Atmospheric Administration: Yes, and when they went away during periods of mass extinctions, they were gone for millions of years. Is Mr. Plimer suggesting doing away with the GBR for millions of years is an appropriate price to pay for short-term fossil fuel profits? The big killer of reefs was because sea level dropped and water temperature decreased Mark Eakin Scientist, Coordinator of NOAA’s Coral Reef Watch, National Oceanic and Atmospheric Administration: No, reefs were lost during major extinction events caused by high levels of CO2 and runaway warming. In the past, reefs thrived when water was warmer and there was an elevated carbon dioxide content of the atmosphere. Peter Landschützer Group Leader, Max Planck Institute for Meteorology: Marine heatwaves have been a major driver of coral bleaching1. 1- Frölicher et al (2018) Marine heatwaves under global warming, Nature Katrin Meissner Professor, University of New South Wales: Today’s reefs are suffering from the fast rates of change. Temperatures are rising too fast to adapt to these changes easily. This results in more frequent and more intense heatwaves and therefore mass bleaching. Much slower warming as in the geological record give ecosystems a chance to adapt. In addition, fast increases in CO2 will reduce carbonate ions in the surface waters which makes the waters more corrosive. If CO2 increases at slower rates, other (slow) feedbacks restore carbonate ions. Reef material is calcium carbonate, which contains 44 per cent carbon dioxide. Reefs need carbon dioxide; it’s their basic food. Peter Landschützer Group Leader, Max Planck Institute for Meteorology: This is not correct. CO2 dissolves in seawater, forming carbonic acid, bicarbonate ion, and carbonate ion. During these reactions, free hydrogen ions are released, which lower the seawater pH and result in ocean acidification. Corals form from calcium carbonate, however, due to the increase of dissolved CO2 in seawater and the resulting increase in hydrogen ion, the dominance of dissolved CO2 species shifts from carbonate ion to bicarbonate ion to maintain chemical equilibrium. This is nicely illustrated in the Bjerrum plot. Therefore, in fact, increasing CO2 levels is not food for corals, but makes the dissolution of CaCO3 more likely. Source: Wikimedia We are not living in a period of catastrophic climate change. The past tells us it’s business as usual. Alexis Berg Research Associate, Harvard University: Absent emission reductions, global mean temperature will likely rise by 3 to 5 °C by 2100 or so. That’s not business-as-usual. It’s a change of geological proportions, almost instantaneous on geological timescales. The last time the Earth was this warm was millions of years ago, and the face of the Earth was markedly different. Katrin Meissner Professor, University of New South Wales: Current CO2 concentrations have not been encountered by Earth for at least 3 million years. Last time the climate was in equilibrium with today’s CO2 concentrations, sea levels were much higher (order of magnitude of 10 meters), temperatures were well beyond the Paris Agreement. The rates of change are unprecedented. Current rates of change in CO2 are at least 10 times faster than in any records of past climate. It has never been shown that human emissions of carbon dioxide drive global warming. Alexis Berg Research Associate, Harvard University: Literally the whole field of climate science for the last 30 years has shown this. Katrin Meissner Professor, University of New South Wales: This is wrong and has been shown in multiple publications, including the IPCC fifth assessment report. Mark Richardson Research Associate, Colorado State University/NASA JPL: Among other evidence, we have directly measured the amount of heating caused by CO2, using instruments pointed at the sky1. We know the CO2 rise is due to human activity, and this heating is sufficient to explain the observed warming. 1- Feldman et al (2015) Observational determination of surface radiative forcing by CO2 from 2000 to 2010, Nature Climate models have been around 30 years. They have all failed. Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: See this previous Climate Feedback review for rebuttal. Alexis Berg Research Associate, Harvard University: Global warming is happening essentially as projected by climate models. The mean warming, the spatial and temporal pattern of that warming, the impact on the water cycle, etc. Mark Richardson Research Associate, Colorado State University/NASA JPL: The models projected warming, with faster warming at the northern high latitudes. This page includes studies showing that Plimer’s statements are inaccurate. Modellers assume carbon dioxide drives climate change Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: This is not an assumption. Modellers simply implement the basic laws of physics and chemistry into these numerical models, which then show what we’ve known for over a century—CO2 is a powerful greenhouse gas, which has the potential to change the climate if its concentration in the atmosphere is significantly increased. Mark Richardson Research Associate, Colorado State University/NASA JPL: This is false. The models include quantum physics and the transfer of heat and radiation according to the laws of physics. They also include things like changing solar activity. That CO2 is the single largest cause of climate change is an output of the calculations. The role of the sun and clouds was not considered important by modellers. They are the major drivers for the climate on our planet. Martin Singh Postdoctoral Research fellow, Harvard University: The role of solar variations is considered in climate-model simulations of the past, and projections of future climate change1. Clouds are considered extremely important by all climate modellers. (See, for example, here.) Variations in solar irradiance have caused only a very small change to the planet’s overall energy balance over the last century or so. On the other hand, greenhouse gas emissions have caused a much larger change to the planetary energy balance, and this has led to global warming. Clouds provide an important feedback to climate change, but they cannot reasonably be described as a “driver” of climate change. There must be some other factor that causes the clouds to change. (E.g. changes in the surface temperature owing to greenhouse-gas emissions). Source: IPCC 1- Matthes et al (2017) Solar forcing for CMIP6 (v3.2), Geoscientific Model Development Mark Richardson Research Associate, Colorado State University/NASA JPL: This is false, and it’s just as false as the last time Plimer claimed this. Solar activity and clouds are included in climate models. Here’s a paper from 2006 talking about how clouds are the largest source of uncertainty in the amount of future global warming1. 1- Soden and Held (2006) An Assessment of Climate Feedbacks in Coupled Ocean–Atmosphere Models, Journal of Climate We emit a trace atmospheric gas called carbon dioxide at a time in planetary history of low atmospheric carbon dioxide. Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: Ian Plimer contradicts himself within the same article, after previously claiming there are no carbon emissions. Peter Landschützer Group Leader, Max Planck Institute for Meteorology: Carbon dioxide levels today have exceeded 400 ppm (see measurements at Mauna Loa), whereas ice-core records show that such levels have not existed in the past 800,000 years (see data here). The geological history of the planet shows major planetary climate changes have never been driven by a trace gas Martin Singh Postdoctoral Research fellow, Harvard University: This is incorrect. Concentrations of CO2 and other trace gases are known to be important for climate change throughout Earth’s history, from the snowball Earth events hundreds of millions of years ago to the ice age cycles of the last million years. (In the latter case, changes in CO2 concentration act as a feedback to changes in Earth’s orbit, but they must be considered in order to explain the observed changes.) Climate change is normal and continual. Mark Richardson Research Associate, Colorado State University/NASA JPL: Plimer’s argument is that “climate change is normal and continual” therefore we can’t or shouldn’t do anything about the current climate change that’s being caused by humans. This is a bit like arguing that radiation is normal and continual, so if there was a risk of someone using nuclear weapons on your city then you shouldn’t try to do anything about that, either. When cycles overlap, climate change can be rapid and large. Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: There is no evidence of any kind to suggest a combination of natural factors is in any way responsible for the current warming we are experiencing. Current warming is over 100% man-made. Sporadic events such as supernovas[…] can also change climate. Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: No1. 1- Dunne et al (2016) Global atmospheric particle formation from CERN CLOUD measurements, Science volcanic eruptions can also change climate. Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: A non-sequitur. Volcanic eruptions cool the climate due to the emission of sulphate aerosols into the upper atmosphere. This is the exact opposite of the current warming we are experiencing. The main greenhouse gas is water vapour[…] Peter Landschützer Group Leader, Max Planck Institute for Meteorology: The IPCC report clearly highlights that CO2 is the most important greenhouse gas regarding the change in anthropogenic radiative forcing since 1750. Source: IPCC Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: This entire paragraph is a non-sequitur. Water vapour’s role as a greenhouse gas is entirely irrelevant to the effect increasing atmospheric CO2 concentrations are having on Earth’s radiative equilibrium. Alexis Berg Research Associate, Harvard University: What’s the point of all this? Is this somehow meant to convince readers that climate scientists don’t know about the water cycle and geophysical fluid dynamics? None of this contradicts the fact that increase greenhouse gas concentrations will warm the climate.Carbon dioxide is a non-condensable atmospheric gas like nitrogen and oxygen Mark Richardson Research Associate, Colorado State University/NASA JPL: This is why it is more important than water vapour in forcing the climate to change. If you add a lot of water vapour to the air, it rains out in hours to days, before it can trap enough heat to warm things up. When we burn fossil fuels, the amount of CO2 in the air will remain higher for at least 100 years. It sticks around for long enough to drive long-term changes in the climate. Martin Singh Postdoctoral Research fellow, Harvard University: Except that, unlike nitrogen and oxygen, carbon dioxide’s molecular structure allows it to absorb infrared radiation, thereby making it a greenhouse gas. Without carbon dioxide, all life on Earth would die Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: And without water, humans would die but we still tend to avoid living under water. Mark Eakin Scientist, Coordinator of NOAA’s Coral Reef Watch, National Oceanic and Atmospheric Administration: This is one of the few things the author gets right. Unfortunately, he forgets the importance of “all things in moderation”. Mark Richardson Research Associate, Colorado State University/NASA JPL: This is ridiculous alarmism and irrelevant. No one proposes removing all carbon dioxide from the atmosphere. It’s just that with more CO2 in the atmosphere, Earth gets hotter and there are consequences of that. Plants need almost three times today’s carbon dioxide content of the atmosphere to thrive. For decades horticulturalists have pumped carbon dioxide into glasshouses to increase yields.Alexis Berg Research Associate, Harvard University: Yes but in the natural world increased CO2 concentration is associated with changes in climate that may be detrimental to plants (warming, changes in precipitation, etc.). In fact, there’s growing evidence that while increasing CO2 has indeed been fertilizing vegetation globally in the last few decades, climate change is starting to negatively impact it. [For more information on this topic, read our review “In CNN interview, William Happer misleads about the impact of rising carbon dioxide on plant life”]In the past, warming has never been a threat to life on Earth. Why should it be now? Alexis Berg Research Associate, Harvard University: Maybe not slow, progressive warming. Abrupt warming probably is. There are past examples of that. Besides, the worry is not about “all life on Earth” (strawman argument): it’s first and foremost about human civilization, which has developed over the last 10,000 years in a very stable climate. A sedentary humanity with 8 billion people is likely going to suffer from a geological-scale +4 °C planetary warming within a couple centuries… Mark Richardson Research Associate, Colorado State University/NASA JPL: There are plenty of studies showing mass extinction events during past warming. Like during the Paleocene-Eocene Thermal Maximum, where warming was slower than today1,2,3. The warming was eventually larger than we’ve seen so far, but it’s up to our policy choices as to whether we want to make things hotter than that extinction event or not. Arcila and Tyler (2017) Mass extinction in tetraodontiform fishes linked to the Palaeocene–Eocene thermal maximum, Proceedings of the Royal Society B Gibbs et al (2006) Nannoplankton Extinction and Origination Across the Paleocene-Eocene Thermal Maximum, Science Yamaguchi and Norris (2015) No place to retreat: Heavy extinction and delayed recovery on a Pacific guyot during the Paleocene–Eocene Thermal Maximum, Geology Mark Eakin Scientist, Coordinator of NOAA’s Coral Reef Watch, National Oceanic and Atmospheric Administration: No, in fact, past extinction of corals occurred at times of high CO2 and runaway warming. if we halved today’s atmospheric carbon dioxide content, all life would die. Peter Landschützer Group Leader, Max Planck Institute for Meteorology: This claim is contradicted by measurements: Ice core records show several periods within the past 800,000 years (see again here) where the carbon dioxide content in the atmosphere was about 200ppm, whereas today we have reached 400ppm (or 0.04% as the author writes below). Our bodies contain carbon compounds. If we were so passionately concerned about our carbon footprint, then the best thing to do is to expire. Mark Richardson Research Associate, Colorado State University/NASA JPL: This is false. The natural carbon cycle keeps atmospheric CO2 amounts approximately in balance. The changes in atmospheric CO2 are almost entirely due to releasing trapped carbon into the air. The single biggest contributor is digging up carbon that’s trapped in fossil fuels and then burning them to release the CO2. A secondary one is releasing carbon trapped in things like forests and peat. Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: This is incorrect unless our bodies were sequestered into an isolated component of the carbon cycle such as buried fossil fuel reserves. Otherwise, carbon is cycled regularly between the different components of the carbon cycle, while as a whole the system is in relative equilibrium. This only changes when we liberate isolated reserves of carbon and add them to the more “active” pools, as we are doing with the extraction and combustion of fossil fuels. In our lifetime, there has been no correlation between carbon dioxide emissions and temperature Mark Richardson Research Associate, Colorado State University/NASA JPL: This is false. Our total emissions correlate strongly with temperature, just as expected. The CDIAC global emissions data are only available until the end of 2014, but the total emissions correlate with global temperature. Over the last 50 years of the datasets the correlation coefficient is 0.93 (where 0 means no correlation and 1 means perfect correlation). after a natural orbitally driven warming, atmospheric carbon dioxide content increases 800 years later Katrin Meissner Professor, University of New South Wales: During natural climate variability, temperature and CO2 are tightly linked, with feedbacks going both ways. Even if in some cases temperature increased before CO2, the majority of warming occurred after the increase in CO2. Rather than atmos­pheric carbon dioxide driving temperature, it is the opposite.Martin Singh Postdoctoral Research fellow, Harvard University: The increase in atmospheric carbon dioxide concentration observed over the last century or so is entirely due to human activity. In fact, the natural world is currently absorbing carbon dioxide from the atmosphere, partly offsetting our emissions. An important question in climate science is the extent to which the natural world (oceans and biosphere) can continue to partially offset our emissions in the future, or if the natural world will become a source of carbon emissions, Geology shows us again there is no correlation between atmospheric carbon dioxide and temperature Katrin Meissner Professor, University of New South Wales: Thats is wrong. Ice cores show a tight correlation between temperature and greenhouse gas concentrations. Proxy records of temperature (blue), CO2 concentration (green), and dust content (red) from an Antarctic ice core.Source: Wikimedia Each of the six major past ice ages began when the atmospheric carbon dioxide content was far higher than at present. Martin Singh Postdoctoral Research fellow, Harvard University: No, the carbon dioxide concentration has not been higher for at least 800,000 years. There have been at least six ice ages in that time. See here. In the past decade China has increased its carbon dioxide emissions by 53 per cent, 12 times Australia’s total carbon dioxide output of 1.3 per cent of the global total.Katrin Meissner Professor, University of New South Wales: The 1.3% become much larger if we look at per capita emissions. And much much larger when we include emissions from exported coal from Australia. Following that logic, I suggest we all stop paying taxes, because our individual contribution is much less than 1.3% and surely would not make a difference?"
https://science.feedback.org/review/bedrock-heat-flow-studies-made-no-claim-about-human-caused-melting-climate-change-dispatch-james-edward-kamis/,Inaccurate,"Climate Change Dispatch, James Edward Kamis, 2018-08-07",[A] series of just-released studies by working-level scientists prove that geological and not atmospheric forces are responsible for melting of Earth’s polar ice sheets.,,Misrepresents source: These studies do not support the article's claim and say nothing that challenges the human cause of glacial ice loss.,"The studies that this article points to make no such claim. This research characterizes the varying temperature conditions at the base of glaciers that cause them to either freeze to the ground or sit on thawed ground. This has important implications for understanding how different portions of the ice sheet will respond to global warming, but it does not explain the glacial ice loss measured over the last century.","In what amounts to dissension from National Aeronautics and Space Administration (NASA) climate change policy, a series of just-released studies by working-level scientists prove that geological and not atmospheric forces are responsible for melting of Earth’s polar ice sheets.",,"This article at Climate Change Dispatch points to two studies published on geothermal heat flow beneath ice sheets to support its claim: one on the Greenland Ice Sheet1 and one on a portion of Antarctica2. However, neither study makes or supports the claim that geothermal heat—rather than human-caused global warming—is the driver of glacial ice loss. The Climate Change Dispatch article was published in August 2018, but has continued to spread across social media and reappear through posts on other websites, leading to more than 40,000 shares on Facebook at the time of this review. In 2017, one of the authors of this study (NASA Jet Propulsion Laboratory Senior Research Scientist Erik Ivins) was contacted by the fact-checking website PolitiFact. Ivins told them: “The study itself is about steady state conditions that would exist at the bottom of the ice sheet for many many millions of years. We think of climate change as occurring 10 years, 100 years, maybe 500 years—our study has nothing to do with those time scales[…] Nothing in our paper has anything to do with climate change.” Geothermal heat flow occurs everywhere on the planet because the interior of the Earth is warmer than the exterior, but heat flow varies based on the geology beneath a location. This can be important for understanding ice sheet behavior, because glaciers that are frozen to the ground typically move more slowly than glaciers with liquid water at their base. Thawed ground beneath glaciers is common because the ice and snow acts as insulation. But variations in geothermal heat flow can influence whether the ground is thawed or frozen, or how much water is produced at the base of a glacier. Therefore, estimates of geothermal heat flow help improve ice sheet models that are used to simulate responses to things like modern global warming. The Greenland study1 evaluated the geologic cause of the pattern of geothermal heat flows around Greenland and concluded that the pattern is likely the result of a hot portion of the Earth’s mantle passing beneath Greenland 50 to 80 million years ago. (That portion of the mantle now lies beneath Iceland.) In the study, the researchers focus on contributing information that will make models more accurate, writing, “[W]e believe the new map provides an important thermal boundary condition for ice-sheet models and will improve the spatial distribution of predicted thawed bed in these models. Our new heat flux map and its uncertainties will help to constrain estimates of basal temperature and the basal thermal state, which in turn, will help to provide more realistic models of ice dynamics and improve the knowledge of subglacial hydrology distribution across Greenland.” The study makes no mention of geothermal heat flow causing a net loss of ice from Greenland over the last century. It does not describe a recent change in geothermal heat flow, but rather a geographic pattern of heat flow with an ancient origin. The Antarctica study2 used model simulations to estimate realistic patterns of heat flow beneath a section of the West Antarctic Ice sheet resulting from a hypothesized hot portion of mantle rock beneath the continent. The authors compared the simulations to existing measurements of heat flow and temperatures and water content at the base of the ice sheet to test whether the simulations were realistic. Like the Greenland study, the Antarctica study said nothing about a potential link between increasing heat flow in the Earth’s crust and recent ice loss. Instead, it describes a geologic condition that has likely existed for tens of millions of years and focuses on informing projections of future ice loss due to global warming. “[B]asal conditions are of major importance to the proper formulation of numerical simulations of ice sheet evolution in a warming climate,” the authors wrote. The Climate Change Dispatch article does not link directly to the study, but instead links to a NASA press release. It also mistakes the headline of the press release for the title of the study. In contrast to the claims in the Climate Change Dispatch article, the NASA press release states, “Although the heat source isn’t a new or increasing threat to the West Antarctic ice sheet, it may help explain why the ice sheet collapsed rapidly in an earlier era of rapid climate change, and why it is so unstable today.” 1- Martos et al (2018) Geothermal heat flux reveals the Iceland hotspot track underneath Greenland, Geophysical Research Letters 2- Seroussi et al (2017) Influence of a West Antarctic mantle plume on ice sheet basal conditions, Journal of Geophysical Research: Solid Earth UPDATES: 24 Nov. 2019: After this post was published, a number of minor edits were made to the title and text to improve clarity."
https://science.feedback.org/review/new-york-times-op-ed-claiming-scientists-underestimated-climate-change-lacks-supporting-evidence-eugene-linden/,-0.8,"The New York Times, by Eugene Linden, on 2019-11-08.",,"""How Scientists Got Climate Change So Wrong""",,,,,"This op-ed by author Eugene Linden, published under the headline “How Scientists Got Climate Change So Wrong”, argues that climate scientists have long underestimated climate change. The article discusses the state of science as far back as the 1950s but focuses on the period since the 1990s, claiming that we are now seeing climate impacts previously thought to be far in the future. Scientists who reviewed the article found that some of the evidence used to support this argument is based on a misrepresentation of the state of scientific knowledge at points in the past. Although the article discusses some topics accurately, such as noting advances in the understanding of ice sheets over the years, it fails to acknowledge many long-accurate predictions that show how useful climate projections have been in warning of the impacts of climate change. In the annotations below, scientists highlight specific reports and studies that don’t match the descriptions given in the article. For example, the article states that the First Assessment Report of the Intergovernmental Panel on Climate Change, published in 1990, concluded that “climate change would arrive at a stately pace”. But if anything, that report projected slightly more rapid warming than what the Earth has experienced so far—partly because humans have emitted a little less greenhouse gas than the scenario used in the report to project warming.See all the scientists’ annotations in context. You can also install the Hypothesis browser extension to read the scientists’ annotations in context.GUEST COMMENTS: Summer Praetorius Research Geologist, (views are my own): The main flaw in the author’s argument that scientists have “underestimated” the rate and severity of climate change is that the author predominantly points to recent extreme events as evidence of what scientists “failed to predict” (such as the heat wave that extended into the Arctic and drove rapid melting of the Greenland Ice Sheet or recent hurricanes). The author implies that scientists did not give the public fair warning about the potential of such events. Firstly, scientists cannot predict the particular extreme events that will unfold decades in the future. What they can and did do (quite accurately in the IPCC assessments) is to provide estimates for long-term projections based on the best available data and models. Against this long-term backdrop of global change will inevitably be the local and regional-scale extreme events and tipping points that are inherently difficult to predict. The author cites one such consensus report from nearly 2 decades ago: “Abrupt Climate Change: Inevitable Surprises”, which in the very title conveys this basic message—climate change will manifest in abrupt and surprising ways. Abrupt climate change by its very nature is difficult to predict. Despite this inherent difficulty, there has been scientific research and progress in trying to assess the likelihood of certain tipping points1. And to try and anticipate early warning signs prior to critical transitions. For example, this study2 and a more recent report from 2013: “Abrupt Climate Change: Anticipating Surprises”3. Secondly, while I do agree that awareness of abrupt climate change and the ways in which long-term changes will increase the severity and probability of extreme events is generally lacking among the wider public, to somehow blame this on the scientists who have been working to understand and disseminate this knowledge for decades is a complete mislocation of blame. The author completely neglects the wider social and political context through which perception of scientific understanding and climate action/adaption has occurred. None of this is to say that scientists knew everything and got it all right decades ago. Of course they didn’t. To quote the author, “Science is a process of discovery. It can move slowly as the pieces of a puzzle fall together and scientists refine their investigative tools.” So, yes, scientists are still actively working to understand more about the dynamics of abrupt climate and potential ways to anticipate inherently “unpredictable” phenomena, all while trying to keep up with the pace of climate change. 1- Lenton et al (2008) Tipping elements in the Earth’s climate system, PNAS 2- Scheffer et al (2012) Anticipating Critical Transitions, Science 3- Abrupt Impacts of Climate Change: Anticipating Surprises, US National Academy of SciencesREVIEWERS’ OVERALL FEEDBACK: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Alexis Berg Research Associate, Harvard University: In my view, this article misrepresents the history of climate science (in particular, what was known from the 70s to 90s) to try to make up a case that climate scientists “got climate change so wrong”, i.e., completely underestimated its pace and amplitude. I found numerous factual errors and mis-interpretations in this presentation. The reality is, since at least the 80s, climate scientists have been making broadly consistent projections (to whomever was listening). The observed pace of warming is on par with these projections—not faster. What’s true is that some impacts of that warming are happening faster than initially anticipated. That includes the melting of polar sea ice and ice caps. The author here focuses a lot on these aspects, but these are just one aspect of climate change, amongst many others—for which changes are unfolding essentially as expected. So, overall, to me this article presents an incomplete and biased view of climate change. I found the title, in particular, very problematic (it may not have been written by the author, though, but instead by the paper). Amber Kerr Researcher, Agricultural Sustainability Institute, University of California, Davis: Most of the specific facts and statistics in this op-ed are correct, but the overall effect is significantly misleading. The author’s central point is that scientists have been drastically underestimating the scope and the pace of climate change until just the past decade or so, and recent events such as permafrost melting, ice cap loss, and extreme weather events have caught them by surprise. This is simply not true. Predictions on the overall pace of global warming, and on its specific effects, have been quite consistent (and broadly accurate) since at least 1990, and in some cases since the late 1970s. For example, the cover story of TIME Magazine on October 19, 1987 was titled “The Heat is On.”1 This article warned the American public that “man-made contributions to the greenhouse effect, mainly CO2 that is generated by the burning of fossil fuels, may be hastening a global warming trend that could raise average temperatures between 2 degrees F and 8 degrees F by the year 2050.” That is, if anything, somewhat higher than current predictions. Similar critiques can be made of Mr. Linden’s claim that economists were universally unconcerned about the costs of climate change. Even in the late 1990s and early 2000s, that was not true. He cites William Nordhaus to make his point, but he doesn’t cite any other economic damage estimates, such as those made by Richard Tol in 20021 or, even more on the pessimistic end, Nicholas Stern in 20062. I especially object to the article’s title: “How Scientists Got Climate Change So Wrong.” It implies that inaction on climate change can largely be blamed on unimaginative scientists conforming to a status quo belief that climate is nearly immovable and human perturbations are insignificant. According to Linden, scientists didn’t think “abrupt climate change” was possible until the publication of some Greenland ice core data in the mid-1990s and a paleoclimate summary report in the early 2000s. That is not really true. Scientists were sounding the alarm about rapid anthropogenic climate change as early as the late 1970s. (I studied with climatologist Stephen Schneider at Stanford in the late 1990s, and he was just as concerned about climate change then as he was a decade later.) This ongoing calamity, in which climate scientists presented well-grounded and deeply worrying predictions to policymakers only to be ignored, was described very well in another NY Times article, “Losing Earth: The Decade We Almost Stopped Climate Change“. Mr. Linden’s goal with this op-ed may have been to drum up increasing public concern for climate change. If so, that is a worthy goal, but I believe he is going about it in the wrong way—by criticizing climate scientists for their supposed timidity and failed predictions, when in fact climate scientists have presented a remarkably consistent series of predictions for at least the past three decades (even if those predictions have fallen on deaf ears). 1- Tol (2002) Estimates of the Damage Costs of Climate Change, Part II. Dynamic Estimates, Environmental and Resource Economics 2- Stern et al (2006) Stern Review: The Economics of Climate Change, HM Treasury Lauren Simkins Assistant Professor, University of Virginia: This article sheds light on how the “worst case” scenarios for future climate and sea level could be worse than previously modeled. The presented science is largely accurate and supports current peer-reviewed scientific literature on the topic. In a few cases, clarification or disclaimers are needed to reflect uncertainty in the current state of ice sheets and their contributions to sea level as some statements in the article portray definitive certainty when that is not entirely the case. Peter Neff Assistant Research Professor, University of Minnesota: To blame the very scientists who identified global warming and continue to monitor its impacts across the world, while ignoring the active efforts in support of disinformation is grossly irresponsible. The author cites many facts, for instance about Antarctic glaciology, but omits important details that expand the timeline of research and warnings back 40 years. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Annotations: The statements quoted below are from the article; comments are from the reviewers (and are lightly edited for clarity). How Scientists Got Climate Change So Wrong Few thought it would arrive so quickly. Now we’re facing consequences once viewed as fringe scenarios. Alexis Berg Research Associate, Harvard University: This is not factually correct. Global warming projections have been essentially the same since at least the Charney report in 19791, and even before that (in the sense that the central estimate of climate sensitivity to CO2 is still the same). Overall warming has proceeded in the real world essentially as projected—not slower, not faster. Many predicted aspects of climate change, such the spatial and temporal pattern of that warming (e.g. more warming over land and at higher latitudes), changes in the water cycle, in extremes events, etc.. are also borne out in observations, at least qualitatively. What’s true is that some impacts of the warming on polar ice, such as decrease in Arctic sea ice, melting of the ice caps in Greenland and Antarctica, are happening faster than predicted early on—but that’s essentially because knowledge of these systems was very limited at the time (and thus predictions were very cautious). Overall it seems to me, if one tries to be objective, that scientists got climate change right for the most part—so far. 1- National Research Council (1979) Carbon Dioxide and Climate: A Scientific Assessment Amber Kerr Researcher, Agricultural Sustainability Institute, University of California, Davis: I agree with Alexis Berg regarding the overall premise of this piece. Overall, climate scientists’ predictions have, on average, been roughly correct for quite a few decades now. This opinion piece by Eugene Linden seems to selectively present historical predictions that turned out to be underestimates, while ignoring those that were right-on or even overestimates. For example, in 1979, James Hansen and others made an educated guess that global temperatures would increase by about 3°C in 2035. That (fortunately) looks like it will turn out to be a significant overestimate. For decades, most scientists saw climate change as a distant prospect. We now know that thinking was wrong. Alexis Berg Research Associate, Harvard University: I am not sure what “decades” this is about. Perhaps in the 60s and 70s. But ever since modeling studies and projections began in earnest, e.g. in the 80s and 90s, projections have indicated significant warming by, for example, 2100. Victor Venema Scientist, University of Bonn, Germany: More than two decades ago (in 1997), Eugene Linden wrote: “Scientists have assumed that any change caused by humans would occur over many decades. They are no longer so sure.” There is some wiggle room, but these two claims mostly do not match. Had a scientist in the early 1990s suggested that within 25 years a single heat wave would measurably raise sea levels, at an estimated two one-hundredths of an inch, bake the Arctic and produce Sahara-like temperatures in Paris and Berlin, the prediction would have been dismissed as alarmist. Alexis Berg Research Associate, Harvard University: Actually, climate models from the first IPCC report in 1990 were projecting more warming than subsequent reports (I believe because they didn’t account for aerosols at the time, which cool the climate, overestimated future CO2 emissions, and didn’t account for ocean dynamics). Amber Kerr Researcher, Agricultural Sustainability Institute, University of California, Davis: The IPCC absolutely was predicting significant and relatively rapid warming in its first report in 1990. Their best estimate was 0.3°C per decade throughout the 21st century (thus, 3.3°C by 2100) under “business as usual emissions,” which of course are higher now than they were then. This is comparable with current estimates. Furthermore, the danger was being reported in the popular press even earlier than 1990. For example, on October 19, 1987, TIME Magazine ran a cover story titled “The Heat is On.” A key quote from that article, paraphrasing climatologist Stephen Schneider, states that “man-made contributions to the greenhouse effect, mainly CO2 that is generated by the burning of fossil fuels, may be hastening a global warming trend that could raise average temperatures between 2 degrees F and 8 degrees F by the year 2050.” That is not exactly a “stately pace.” Victor Venema Scientist, University of Bonn, Germany: Which would have been fair if our understanding of the climate system was not yet sufficient 25 years ago to predict whether heat waves would become worse and by how much. That is not a trivial question, local heat waves are not just determined by the global annual mean temperature. But in the case of climate, this deliberation has been accompanied by inertia born of bureaucratic caution and politics. Victor Venema Scientist, University of Bonn, Germany: No evidence provided. A recent essay in Scientific American argued that scientists “tend to underestimate the severity of threats and the rapidity with which they might unfold” and said one of the reasons was “the perceived need for consensus.” Lauren Simkins Assistant Professor, University of Virginia: The current IPCC projections are not intentionally underestimated. We are still at a stage of discovering new processes that are important to the ice-ocean-climate system. Therefore, taking a step forward of being able to incorporate important processes in models, to varying degrees, limits the uncertainty and magnitude of future changes. For example, recent numerical model work by Robel et al1 has demonstrated the importance of a single ice-destabilizing process in sea-level projections that can increase the magnitude and uncertainty in sea-level scenarios. This is just one example of how a single process or condition impacts the (un)certainty in future sea levels and thus limits community planning that takes into account a large range of scenarios, in particular the high-end scenarios that will be more costly for mitigation infrastructure. 1- Robel et al (2019) Marine ice sheet instability amplifies and skews uncertainty in projections of future sea-level rise, PNAS In 1990, the Intergovernmental Panel on Climate Change, the United Nations group of thousands of scientists representing 195 countries, said in its first report that climate change would arrive at a stately pace Alexis Berg Research Associate, Harvard University: This is simply false. Quoting the summary for policy makers from that first report in 1990: “Based on current models, we predict: under business-as-usual, increase of global mean temperature during the [21st] century of about 0.3 °C per decade (with an uncertainty range of 0.2 to 0.5 °C per decade); this is greater than that seen over the past 10,000 years; under other … scenarios which assume progressively increasing levels of controls, rates of increase in global mean temperature of about 0.2 °C [to] about 0.1 °C per decade.” Like I mentioned above, these early models were actually running even hotter than current models. [The 1990 IPCC report said] that the Antarctic ice sheets were stable Lauren Simkins Assistant Professor, University of Virginia: Although this was the conception, the idea that the Antarctic ice sheet was stable in the 1990s largely stems from a lack of continental scale observations provided by remote sensing and a lack of widespread in situ, on-ice observations. Therefore, late 20th century thought about a stable Antarctic ice sheet stemmed from negative evidence, rather than positive evidence supported by observations. Alexis Berg Research Associate, Harvard University: Again, technically, not true. The report summary indicates that: “The West Antarctic Ice Sheet is of special concern. A large portion of it containing an amount of ice equivalent to about 5m of global sea level, is grounded far below sea level. There have been suggestions that a sudden outflow of ice might result from global warming and raise sea level quickly and substantially”. The report concludes that: “Within the next century it is not likely that there will be a major outflow of ice from West Antarctica due directly to global warming”—but not that it is “stable”. That report also emphasized uncertainties in that respect a whole lot. Peter Neff Assistant Research Professor, University of Minnesota: As Lauren also highlights, the IPCC has struggled to represent the possibility of more rapid collapse of the Antarctic ice sheet, particularly West Antarctica. Antarctica was viewed as more stable before the continent-scale satellite observations beginning in the 1990s and improved glaciological observations. However, Mercer gave a strong, clear warning in the journal Nature in 19781, with the article “West Antarctic ice sheet and CO2 greenhouse effect: a threat of disaster.” His predictions remain a central paradigm in Antarctic glaciology and scientists from the US and UK are currently rushing to the most vulnerable glacier in Antarctica—Thwaites Glacier—to further clarify how much sea level rise may come from this location, and importantly, how fast. The amount of ice at play here is on the order of 10 feet of global mean sea level equivalent. 1-Mercer (1978) West Antarctic ice sheet and CO2 greenhouse effect: a threat of disaster, Nature Relying on the climate change panel’s assessment, economists estimated that the economic hit would be small Alexis Berg Research Associate, Harvard University: The low economic costs of global warming estimated by, for example, W. Nordhaus, have more to do with his methodology (the DICE model and its damage function) than with climate projections themselves. Like I said, models at that time indicated even faster warming. Amber Kerr Researcher, Agricultural Sustainability Institute, University of California, Davis: Not all economists. For example, in the late 1990s and early 2000s, widely cited economist Richard Tol published analyses indicating that doubled CO2 would probably cost at least 0.6% of global GDP by 2100, and quite possibly as much as 1.2% of GDP if climate sensitivity was worse than expected or adaptation was less successful than anticipated1. 1- Tol (2002) Estimates of the Damage Costs of Climate Change, Part II. Dynamic Estimates, Environmental and Resource Economics all of those predictions turned out to be completely wrong Alexis Berg Research Associate, Harvard University: Highly misleading. The author just focused on a subset of predictions (i.e., ice cap stability), and/or, as I indicated above, misrepresented them. Saying “all of those predictions” is thus highly misleading. Amber Kerr Researcher, Agricultural Sustainability Institute, University of California, Davis: Alexis Berg is correct: to say “all these predictions were completely wrong” is a highly exaggerated and cherry-picked conclusion on the author’s part. Most climate predictions from the 1990s have been more or less borne out so far. So far, the costs of underestimation have been enormous. Victor Venema Scientist, University of Bonn, Germany: No evidence provided on whether this was the cost of underestimation or lack of climate action. Hurricane Harvey gave Houston and the surrounding region a $125 billion lesson about the costs of misjudging the potential for floods Victor Venema Scientist, University of Bonn, Germany: This sentence claims that all of the costs of Harvey should be ascribed to science and none of it to Texas or federal politicians, nor to the media. The climate change panel seems finally to have caught up with the gravity of the climate crisis Alexis Berg Research Associate, Harvard University: This is a bit rich, given that the IPCC is precisely the reason we all know about the climate crisis… more to the point, warming projections since the 90s and the first IPCC report have essentially been the same. What has changed is that it is now 2020, and the time window to cut emissions and limit warming to 2°C globally is closing down. Unfortunately, this dose of reality arrives more than 30 years after human-caused climate change became a mainstream issue. Alexis Berg Research Associate, Harvard University: This is misleading and, to be honest, a bit frustrating, given that 5.4°F warming is precisely the warming the IPCC has warned all along (since the 90s) would happen under business-as-usual emissions. The UN is simply restating that this is where we are currently headed. Amber Kerr Researcher, Agricultural Sustainability Institute, University of California, Davis: Alexis Berg is right again. This value (5.4°F or 3.4°C of warming) is in line with what has consistently been predicted for the past 30 years.Conventional wisdom, in the 1950s, on the pace of major climate change: 8,000 years Each large square = 100 years 1960s through the ’80s: Centuries or millenniums 1990s to today: 5 to 50 years Alexis Berg Research Associate, Harvard University: While this graphic may apply to natural climate variations, I would argue that it doesn’t really apply to current, man-made climate change, in the sense that since at least the 70s scientists understood that climate would respond to human CO2 emissions within decades (i.e., not millennia as implied by that graph). Amber Kerr Researcher, Agricultural Sustainability Institute, University of California, Davis: It is not true that climate scientists in the 1970s and 1980s thought that any significant climate changes would take centuries or millennia. On the contrary, 30-40 years ago, the predictions on the extent and pace of climate change were very similar to today’s predictions. This was reviewed exhaustively in another recent NY Times article, “Losing Earth“. Here are a couple representative quotes: “[A 1978 EPA report warned that] fossil fuels might, within two or three decades, bring about “significant and damaging” changes to the global atmosphere.” “[In 1979, a team of scientists calculated that] when carbon dioxide doubled in 2035 or thereabouts, global temperatures would increase between 1.5 and 4.5 degrees Celsius, with the most likely outcome a warming of three degrees.” The evidence in those ice cores would prove pivotal in turning the conventional wisdom. As the science historian Spencer Weart put it: “How abrupt was the discovery of abrupt climate change? Many climate experts would put their finger on one moment: the day they read the 1993 report of the analysis of Greenland ice cores. Before that, almost nobody confidently believed that the climate could change massively within a decade or two; after the report, almost nobody felt sure that it could not.” Alexis Berg Research Associate, Harvard University: This whole section of the article somehow implies that when scientists found out about abrupt climate change events during the last glacial era (i.e., the Younger Dryas event, and Dansgaard–Oeschger events) is when they fully realized climate could change by 2100 rapidly in response to CO2. I don’t believe this perspective is correct. Abrupt climate swings in the last glacial era are not really relevant to our current, interglacial climate (in which they don’t happen), and the projected climate response to CO2 emissions does not involve such processes. In 2002, the National Academies acknowledged the reality of rapid climate change in a report, “Abrupt Climate Change: Inevitable Surprises” Amber Kerr Researcher, Agricultural Sustainability Institute, University of California, Davis: I do not think it is well justified to tie the publication of this 2002 paleoclimate report to a sudden supposed epiphany in the scientific community about how modern emissions of greenhouse gases would affect global temperature. As Alexis Berg and I have said repeatedly above, climate scientists’ warming predictions have generally been right on track, and have not changed much for the past 30-40 years. (In fact, Swedish chemist Svante Arrhenius described the basic cause and effect of fossil-fuel-induced climate change back in the 1890s. That is not a typo—Arrhenius made a roughly correct quantitative calculation 130 years ago.) Victor Venema Scientist, University of Bonn, Germany: The title of the report alone shows that science did warn that taking the climate system into uncharted territories is dangerous. Specific warnings can only be given once a problem is understood. And even today, 17 years later, a substantial portion of the American public remains unaware or unconvinced it is happening. Victor Venema Scientist, University of Bonn, Germany: Science is a global enterprise as knowledge is universal. That the denial of the reality is an Anglo-American phenomenon suggests that the main problem is not science, but American political problems and the US-Australian media. In the early 2000s, ice shelves began disintegrating in several parts of Antarctica, and scientists realized that process could greatly accelerate the demise of the vastly larger ice sheets themselves. Lauren Simkins Assistant Professor, University of Virginia: Antarctic ice shelf collapse is documented from the mid-1990s onward1,2. 1- Vaughan and Doake (1996) Recent atmospheric warming and retreat of ice shelves on the Antarctic Peninsula, Nature 2- Scambos et al (2003) Climate‐induced ice shelf disintegration in the Antarctic Peninsula, in Antarctic Peninsula Climate Variability: Historical and Paleoenvironmental Perspectives Peter Neff Assistant Research Professor, University of Minnesota: Again, Mercer gave a strong, clear warning on this in 1978, with the article “West Antarctic ice sheet and CO2 greenhouse effect: a threat of disaster.”1 He predicted a southward migration of ice shelf collapse, and eventually an irreversible collapse of the West Antarctic ice sheet. This concept was revisited and reconfirmed in 2009 by Bamber et al2. 1-Mercer (1978) West Antarctic ice sheet and CO2 greenhouse effect: a threat of disaster, Nature 2- Bamber et al (2009) Reassessment of the Potential Sea-Level Rise from a Collapse of the West Antarctic Ice Sheet, Science By 2014, a number of scientists had concluded that an irreversible collapse of the West Antarctic ice sheet had already begun Lauren Simkins Assistant Professor, University of Virginia: It is generally true that conditions are suitable for irreversible collapse of the West Antarctic ice sheet via the process called “Marine Ice Sheet Instability” where an initial forcing of ice sheet retreat progresses inland due to a landward-sloping bed that forces marine-based ice sheets to retreat into yet deeper and deeper water. However, there are potential brakes that could halt this ‘irreversible’ retreat including bumps in the bed topography that the ice is sitting on top of that can act as pinning points as well as increased lateral drag at the ice margins that can slow down ice flow and retreat1,2. However, bed topography beneath the ice is not well-resolved and the jury is still out on whether current retreat is truly irreversible. 1- Jamieson et al (2013) Understanding controls on rapid ice‐stream retreat during the last deglaciation of Marguerite Bay, Antarctica, using a numerical model, Journal of Geophysical Research: Earth Surface 2- Gudmundsson et al (2012) The stability of grounding lines on retrograde slopes, The Cryosphere As recently as 1995, [permafrost] was thought to be stable. Alexis Berg Research Associate, Harvard University: Not accurate. The 1990 IPCC report indicates for instance that: “Higher temperatures could increase the emissions of methane at high northern latitudes from decomposable organic matter trapped in permafrost and methane hydrates ” and “Time-scales for thawing the permafrost […] could be decades to centuries, ” For all of the missed predictions, changes in the weather are confirming earlier expectations that a warming globe would be accompanied by an increase in the frequency and severity of extreme weather. Amber Kerr Researcher, Agricultural Sustainability Institute, University of California, Davis: This is actually one of the most difficult aspects of climate change to predict and correctly attribute. Storm behavior is more complicated and harder to model than changes in average temperature or precipitation. Some aspects of “extreme weather” (e.g. number of Category 5 tropical cyclones) may be expected to increase with global warming, but others (e.g. total number of tropical cyclones, or total number of tornadoes) may not be. So it’s best to proceed with caution when tying climate change predictions to extreme weather events."
https://science.feedback.org/review/claim-of-a-coming-ice-age-misrepresents-the-study-it-relies-on/,Incorrect,"Daily Mail, Fox News, Chris Ciaccia, Stacy Liberatore, 2019-10-31",Scientists studying Antarctica sea ice warn a rise in accumulation could spark the next ice age.,,"Misrepresents source: The study this article is based on does not make or support this claim. The study relates to changes in past ice age periods, which were driven by slow-changing cycles in Earth's orbit.  Flawed reasoning: The fact that past changes in Antarctic sea ice extent can help explain natural ice age swings of atmospheric carbon dioxide does not mean that this process is capable of reversing modern human-caused warming.","This article refers to a study of past ice ages, when warming or cooling caused by cycles in Earth's orbit was amplified by increasing/decreasing greenhouse gases. The study does not claim this process can trigger an ice age, nor does it claim that this could reverse modern warming. Scientists expect the world to continue warming if humans continue emitting greenhouse gases.","Scientists studying Antarctica sea ice warn a rise in accumulation could spark the next ice age. Computer simulations show that an explosion in ice circling the frozen desert would act as a lid on the ocean and block it from exchanging carbon dioxide with the atmosphere. This is capable of causing a reverse greenhouse effect, which would ultimately cool the earth and send our planet into an ice age for the first time in over two million years.",,"The claim of a coming ice age was originally made by Stacy Liberatore at the Daily Mail and Chris Ciaccia at Fox News. However, the authors of the study have explained that these stories misunderstand their research, see Dr Jansen’s comment below and Dr Marzocchi’s on Twitter: Once again, we do NOT claim anything like that. Journalists should learn how to read and/or contact the authors of the research before publishing a load of garbage that only confuses people! @stacyliberatore and @DailyMailUK any plans of getting your act together and fixing this? pic.twitter.com/nqFocqVp2K — Dr Alice Marzocchi (@AliceMarzocchi_) October 31, 2019 So yes, today @Chris_Ciaccia from @foxnews published an article that utterly misrepresents our research just published in @NatureGeosci. For the record: our study does NOT in any way suggest that we may presently be heading towards another ice age! *facepalm* — Dr Alice Marzocchi (@AliceMarzocchi_) October 30, 2019 The Fox News article has been corrected, but when shared on social media, both articles are still featured with a text falsely claiming that we are facing another ice age. As of writing, about 70 thousand users have shared or liked each of these two stories on Facebook with the misleading caption. And other blogs such as Technocracy News, The Global Warming Policy Foundation and the Gateaway Pundit have republished the false claim. UPDATE (4 Nov. 2019): Several outlets have now corrected their articles incorrectly warning of a coming ice age including the Daily Mail, Express, Sky.it, CNET and the New York Post. Malte Jansen Assistant Professor, University of Chicago: The paper addresses the physical mechanisms for glacial-interglacial changes in ocean carbon storage. Specifically, we performed simulations that suggest that a global surface cooling (which is imposed in the model) leads to increased Antarctic sea ice, which triggers changes in the deep ocean circulation and leads to increased ocean carbon storage, thus drawing down atmospheric CO2. Some CO2 drawdown is expected simply as a result of the fact that colder water can dissolve more CO2, but we find that the drawdown is significantly stronger than what would be expected from the solubility effect alone, because of the effects of changes in sea ice and circulation. The direct link between global temperature change and ocean carbon storage is important, because it supports the idea of a positive feedback loop, where some initial temperature change leads to a change in ocean carbon storage and hence atmospheric CO2, which then amplifies the initial temperature anomaly. Such a feedback loop likely played an important role in the glacial cycles. Our study does not at all address current climate change, and I don’t think our results have any applicability to current climate change (primarily because of the very different time-scales but also because we are warming from an already warm climate). However, even a wild extrapolation of our results would not suggest that we are heading towards an ice age. I think the confusion may literally have arisen purely from the fact that our title contains the phrase “global cooling” (in reference to the cooling that has occurred when going from interglacial to glacial climate states in the past)."
https://science.feedback.org/review/human-activities-release-far-more-carbon-dioxide-than-volcanoes-do/,Inaccurate,"Facebook, Anonymous, 2019-08-19","That one little burp by Mt. Etna has already put more than 10,000 times the CO2 into the atmosphere than mankind has in our entire time on the Earth",,"Factually inaccurate: Each year, humans emit far more CO2 than all eruptions around the world combined.","It's true that carbon dioxide is among the gases emitted by volcanic activity. However, it's clear from several lines of evidence that human activities are producing far more carbon dioxide, and volcanoes are not responsible for the observed increase in greenhouse gases.","That one little burp by Mt. Etna has already put more than 10,000 times the CO2 into the atmosphere than mankind has in our entire time on the Earth but don't worry, a scam is in the works to tax you for your miniscule footprint…",,"Carbon dioxide is released into the atmosphere by volcanic eruptions—as well as by passive venting around volcanoes that are not erupting. The amount of CO2 emitted varies from one volcanic feature to another, and varies with time, which makes quantifying global emissions a challenge. However, there are multiple ways of constraining their contribution. The most recent estimate1 puts total global emissions from all volcanic activity at approximately 280 million to 360 million metric tons of CO2 per year. Of this, active eruptions only account for about 2 million metric tons per year. Additionally, there is no evidence that volcanic activity has increased over the last century, while atmospheric CO2 has increased significantly. Human-caused CO2 emissions are much larger than this estimate. Current emissions from fossil fuel burning, industrial processes, and land use change (like deforestation) equal about 39 billion metric tons per year2—at least 100 times greater than the amount released by all volcanic activity, let alone eruptions. Prior to human-caused emissions, Earth’s carbon cycle was in balance. The amount of CO2 released by things like volcanoes, wildfires, and respiration by living things was equal to the amount of atmospheric CO2 taken up by processes like bedrock weathering and photosynthesis. Human-caused emissions are not matched by a human-caused process of CO2 uptake, so this net addition is responsible for the observed increase in atmospheric CO2 since the Industrial Revolution. In addition to these accounting methods for estimating the factors related to the atmospheric CO2 concentration, the source of the CO2 added to the atmosphere can also be determined from the isotopes of carbon in the air. Because the carbon atoms in volcanic CO2 have a different isotope ratio than the carbon atoms in fossil fuel CO2, the measured change in atmospheric carbon-14, carbon-13, and carbon-12 shows that the CO2 added to the atmosphere has come from fossil fuel burning and deforestation—not volcanoes3. 1- Werner et al (2019) Carbon Dioxide Emissions from Subaerial Volcanic Regions (in Deep Carbon, Past to Present) 2- Le Quéré et al (2018) Global Carbon Budget 2018, Earth System Science Data 3- Rubino et al (2013) A revised 1000 year atmospheric δ13C‐CO2 record from Law Dome and South Pole, Antarctica, Journal of Geophysical Research: Atmospheres Tobias Fischer Professor, University of New Mexico: The contribution of volcanoes to the global carbon dioxide (CO2) emissions budget is small1-16 compared to the emission from burning of fossil fuels17. In detail, the contribution of volcanic eruptions can be illustrated by considering recent, well-studied large eruptions, such as the 2014 Holhuraun eruption in Iceland. The massive Holhuraun eruption emitted a cumulative amount of 9,330 kilotons of CO2 (or 9.3 x1012 g CO2)18. The eruption of Etna Volcano in Italy in the year 2006 emitted a cumulative CO2 amount of 644 kilotons (or 0.644 x 1012 g CO2). Another recent and massive eruption was the 2010 Eyjaflallajokul eruption in Iceland that emitted a cumulative amount of CO2 of 5,130 kilotons (or 5.1 x 1012 g CO2)18. While these eruptions have significantly affected local air travel and disrupted the daily lives of the population living in the region, the amount of CO2 emitted is dwarfed by the emissions resulting from human activities. The burning of fossil fuels and production of cement has released 36.3 gigatons of CO2 (or 36,300 x 1012 g CO2) into the atmosphere in 201517. Therefore, the largest CO2 emitting eruption in the past 15 years (Holhuraun in 2014) produced only about 0.026% of the yearly anthropogenic emissions. Indeed, we would need to have about 3,890 such massive eruptions like Holhuraun in one year to produce the equivalent of CO2 emitted due to fossil fuel burning and cement production. However, such large CO2 emitting eruptions are rare and the Holuhraun 2014 eruption is unique in the past 15 years18. The total CO2 emissions for volcanic eruptions for the time frame from 2005 to 2018 was 26.9 megatons (or 26.0 x 1012 g CO2) and, therefore, in an average year only about 2,070 kilotons of CO2 (or 2.0 x 1012 g) are produced from volcanic eruptions18. This means that, during a typical year, volcanic eruptions contribute only about 0.006% of the global anthropogenic CO2 flux. The average CO2 emission of a person living in the USA is about 16 tons of CO2 per year17. Therefore, in any given year volcanic eruptions produce only about as much CO2 as 130,000 Americans, or less than the population of Wyoming—the state with the lowest population in the US. 1- Aiuppa et al (2019) CO2 flux emissions from the Earth’s most actively degassing volcanoes, 2005–2015, Scientific Reports 2- Allard (1992) Global Emissions of helium-3 by subareal volcanism, Geophysical Research Letters 3- Brantley and Koepenick (1995) Measured carbon dioxide emissions from Oldoinyo Lengai and the skewed distribution of passive volcanic fluxes, Geology 4- Burton et al (2013) Deep carbon emissions from volcanoes, Reviews in Mineralogy and Geochemistry: Carbon in Earth 5- Fischer (2008) Volatile fluxes (H2O, CO2, N2, HCl, HF) from arc volcanoes , Geochemical Journal 6- Gerlach (1991) Present-day CO2 emissions from volcanoes, EOS Transactions 7- Hilton et al (2002) Noble gases in subduction zones and volatile recycling, MSA Special Volume: Noble Gases in Geochemistry and Cosmochemistry 8- Kerrick (2001) Present and past nonanthropogenic CO2 degassing from the solid earth, Reviews of Geophysics 9- Le Guern (1982) Les debits de CO2 et de SO2 volcaniques dans l’atmosphere. Translated title: Discharges of volcanic CO2 and SO2 in the atmosphere, Bulletin of Volcanology 10- Williams et al (1992) Global carbon dioxide emission to the atmosphere by volcanoes, Geochimica et Cosmochimica Acta 11- Marty et al (1989) Helium isotopes and CO2 in volcanic gases of Japan, Chemical Geology 12- Marty and LeCloarec (1992) Helium-3 and CO2 fluxes from subaereal volcanoes estimated from Polonium-20 emissions, Journal of Volcanology and Geothermal Research 13- Marty and Tolstikhin (1998) CO2 fluxes from mid-ocean ridges, arcs and plumes, Chemical Geology 14- Moerner and G. Etiope (2002) Carbon degassing from the lithosphere, Global and Planetary Change 15- Sano and Williams (1996) Fluxes of mantle and subducted carbon along convergent plate boundaries, Geophysical Research Letters 16- Shinohara (2013) Volatile fluxes from subduction zone volcanoes: insights from a detailed evaluation of the fluxes from volcanoes in Japan, Journal of Volcanology and Geothermal Research 17- Le Quéré et al (2016), Global Carbon Budget 2016, Earth System Science Data 18- Werner et al (2019) Carbon Dioxide Emissions from Subaerial Volcanic Regions (in Deep Carbon, Past to Present) UPDATES: 4 November 2019: This post was updated to include a comment by Tobias Fischer."
https://science.feedback.org/review/letter-to-un-was-not-signed-by-500-experts-on-climate-science-breitbart/,Misleading,"Breitbart, Thomas D. Williams, 2019-09-24",500 Scientists Write U.N.: ‘There Is No Climate Emergency’.... More than 500 scientists and professionals in climate and related fields have sent a 'European Climate Declaration' to the Secretary-General of the United Nations,,"Misleading: The article gives the impression that these 500 signatories are scientists or experts in the field of climate science, but in reality very few have any research experience related to climate change. Most of the signers are engineers, business professionals, or study non-climate topics in other academic fields: signatories in unrelated fields such as philosophy, medicine, and law together outnumbered climate scientists approximately six to one. Many are associated with advocacy groups that oppose the conclusions of climate science, like the Heartland Institute.  Conflates factual statement and opinion: The article presents the unsupported opinions of these signatories as accurate facts about the science of climate change, but they largely ignore or contradict the evidence available in the published research.","The vast majority of those who signed this letter are either scientists without expertise in climate science or are not scientists. Most are professionals who work or worked in other science disciplines or non-science fields such as business and law. Moreover, most of the letter's claims about climate change are contradicted by the available evidence.",500 Scientists Write U.N.: ‘There Is No Climate Emergency’.... More than 500 scientists and professionals in climate and related fields have sent a 'European Climate Declaration' to the Secretary-General of the United Nations,,"The headline describes the signers as “500 scientists”, and they are later described as “500 scientists and professionals in climate and related fields”. Both descriptions are false, as the list contains many people who are not scientists, and more importantly, almost none of them have research experience related to climate change. Ten fact-checking organizations, including Climate Feedback, reviewed the credentials of a little over 200 of the signatories but could only confirm that 2 had published research in atmospheric or climate science, which means at least 200 of the 500 are not scientists with relevant expertise. And by our count, more of the signatories are math professors, business executives, economists, engineering professors, medical professionals, or individuals primarily engaged in advocacy than individuals who have published in atmospheric or climate science. The largest single group of signers—approximately 60 of the 200 we reviewed from the US, Canada, Brazil, Norway, Sweden, Denmark, Belgium, France, and Germany—includes academics in the physical sciences, such as physics, chemistry, or geology. However, we could not confirm that any have published research relevant to climate change, so they are making a point outside their domain of expertise—as if a geologist made authoritative comments about your health that are contradicted by scientific research. Of the 200 signers we checked, 40% are retired or professors emeritus, indicating they are not actively involved in scientific research and may not be up to date on the latest findings. The affiliations of several of the signers are misleading. For example, Professor Waheed Uddin is listed as an “expert in climate modeling” and “former advisor UN”. However, a public profile of Prof. Uddin describes him as “previously a pavement expert for the United Nations”. At least two signers list themselves as an “IPCC Expert Reviewer”, but this title can be claimed by any member of the public who signs up to receive drafts of IPCC report chapters and submits comments. German fact-checker Correctiv discovered several individuals listed as professors whose titles could not be verified. The letter’s claims about climate science are also unsupported by scientific research or data and were shown to be inaccurate or misleading in a review by climate scientists. Amber Kerr Researcher, Agricultural Sustainability Institute, University of California, Davis: While reviewing the claims related to agriculture, I noted that only 26 out of the 506 signatories (5%) were professionals in biology, ecology, or environmental science. I suspect that the vast majority of signatories had little direct knowledge or understanding of this part of the petition that they signed. This made me curious to delve more deeply into the makeup of the signatory list. I usually try to steer clear of any ad hominem tactics, and instead evaluate claims solely on their own merits. However, the fact that this group is vocally promoting themselves as “knowledgeable and experienced scientists and professionals in climate and related fields” made me wonder if that claim is actually supported by the signatories’ credentials. In a word, the answer is no. I categorized all 506 signatories according to their self-identified field of expertise. Only 10 identified as climate scientists, and 4 identified as meteorologists. (Together, that’s 2.8% of the total.) Signatories in totally unrelated academic fields (for example, psychology, philosophy, archaeology, and law) outnumbered climate scientists by two to one. The most prevalent groups of signatories were geologists (19%) and engineers (21%)—many of whom were implicitly or explicitly involved in fossil energy extraction. Most of the rest were physicists, chemists, and mathematicians. A large fraction of the signatories were not scientists, but rather business executives, writers, activists, and lobbyists (totaling 11.3%). I also noticed a peculiar omission in the list of signatories: women. Among the 506 names, only 24 were female names (with another 15 that were initials-only or unisex). That means that about 95% of the signers were men. Even for male-heavy fields such as geology and engineering, this is a staggering imbalance. I suspect that the imbalance may have been heightened by the fact that the signers skewed heavily toward the older generation – for example, there were 79 emeritus professors on the list (16% of the total). Again, I’d prefer to evaluate claims on their own merits. But if the ECD group is going to tout their own credentials, then it needs to be pointed out that a large fraction of their 506 signatories have credentials like “Peter Champness, Radiologist, Australia”; “Patrick Mellett, architect and CEO”; and “Fintan Ryan, Retired Senior Airline Captain” (to say nothing of the dozens and dozens of fossil fuel employees)."
https://science.feedback.org/review/photo-meme-of-sydney-harbour-incorrectly-claims-no-sea-level-rise-has-occurred/,Inaccurate,"Facebook, Anonymous, 2018-10-12",Unprecedented climate change has caused sea level at Sydney Harbour to rise approximately 0.0 cm over the past 140 years.,,"Factually Inaccurate: Measurements at this location show that sea level rise has occurred.  Misrepresents a Complex Reality: Because tides rise and fall along the coast, a pair of photos taken at different tide phases cannot show you whether long-term sea level rise has occurred.","This meme presents two photos of Fort Denison in Sydney Harbour, claiming they prove that no sea level rise has occurred. However, long-term tide gauge records at that very location (and elsewhere) clearly record sea level rise. These photos do not give the viewer enough information to determine how much sea level rise has occurred.",Unprecedented climate change has caused sea level at Sydney Harbour to rise approximately 0.0 cm over the past 140 years.,"1- White et al (2014) Australian sea levels—Trends, regional variability and influencing factors, Earth-Science Reviews 2- Peltier et al (2017) Comment on “An Assessment of the ICE‐6G_C (VM5a) Glacial Isostatic Adjustment Model” by Purcell et al, Journal of Geophysical Research – Solid Earth","Screenshot illustrating one version of this meme that has been shared online. John Hunter Research Associate, University of Tasmania: The maximum range of the variability in water level due to tides and storm surges at “Sydney Harbour” (the location shown is actually Fort Denison) is around 2 metres (i.e. it varies around mean sea level by around +/- 1 metre). Therefore, if you take a photograph and you don’t quote (or even know) the state of the tide or surge at that time, then all you can say is that the level shown is the mean sea level +/- 1 metre (where I’m here quoting the maximum possible, or limit, of the error; I do this in all of the following). If you take two photographs at different times, then the visual difference between the two water levels only tells you the change in mean sea level to an accuracy of +/- 2 metres. If we suppose that the visual sea level in the two photos is the same (I’d guess that you could only tell this to an accuracy of around 0.5 metres, but let’s ignore this additional error), then all this tells us is that that mean sea level has changed by 0 +/- 2 metres or 0 +/- 2000 mm. If the elapsed time is 140 years (as quoted in the Facebook post), then the rate of sea level rise is constrained to 0 +/- 2000/140 mm/year (or 0 +/- 14 mm/year). This hardly tells us anything useful about mean sea-level rise. The tide-gauge record from Fort Denison is discussed by White et al1. The paper summarises earlier estimates of relative sea-level rise (i.e., the sea-level rise relative to the land, or in other words, sea level rise as “seen” by a tide gauge) as: “You et al. (2009) estimated rates of relative sea level rise at Fort Denison of 0.63 ± 0.14 mm/yr for 1886–2007, 0.93 ± 0.20 mm/yr for 1914–2007 and 0.58 ± 0.38 mm/yr for 1950–2007. Mitchell et al. (2000)estimated a trend of 0.86 mm/yr for 1914–1997.“ Clearly, the “result” from the two photos of Fort Denison (0 +/- 14 mm/year) provides no information which could improve or disprove the results quoted by White et al. You should note that the error estimates quoted by White et al1 (which are presumably +/- 1 standard deviation) are not exactly comparable with the error limits that I have quoted (which would be +/- several standard deviations). However, my statement still stands—the “result” from the two photos of Fort Denison provides no information which could improve or disprove the results quoted by White et al1. Table 4 in White et al[1] gives their own estimate of relative sea-level rise at Fort Denison (here called “Sydney”) as 0.8 mm/year over the period 1966 to 2010, which is broadly consistent with the earlier estimates that they quoted. This is low, but just consistent with the Australian average of 1.5 +/- 0.6 (s.d.) mm/year. In the Discussion of White et al[1], they provide the following caution: “The detailed description of the Sydney Fort Denison tide gauge and its data (Hamon, 1987) highlights a number of uncertainties and potential problems in the earlier parts of this record. Some of these may be related to chart digitising problems and some to registration errors, both physical and in the data recording. Great care should be taken in interpreting a single long record, no matter how much care was taken with it at the time of digitisation and in post-processing. The scales of the phenomena discussed here are of the order of several hundred to thousands of kilometres ….. so we should not rely on single records for predicting long-term and large-spatial-scale phenomena.“ So—don’t take just one tide-gauge record as indicative of global sea level. Thomas Frederikse Postdoctoral researcher, Jet Propulsion Laboratory/California Institute of Technology: In the last 140 years, global mean sea level has risen by about 15 cm. Not sure about my eyes, but detecting a 15cm sea-level difference from these pictures seems difficult. What you could see on the picture is the dark brownish band that is much larger on the right picture than on the left. Assuming that this brownish band denotes the tidal range, the right picture has been taken at low tide, while the left picture has been taken at a much higher tidal level. In Sydney, the typical tidal range is about 1 meter. Therefore, if you compare two pictures to derive sea level changes, the odds are that you’re comparing tidal levels rather than long-term sea-level changes. The catch with sea level is that it’s not just the mean level that rises, but the high tide level will also rise. Therefore, without detailed information on the exact timing of the picture and a tidal chart, one simply cannot derive decimeter-accuracy estimates of sea-level change from these two pictures. Then to sea level in Sydney. At Fort Denison, which is the building in the picture, we have two long tide gauge records. One that covered 1886-1993, and one that started in 1915 and is still measuring today. I’ve plotted both individual records and the average of them. Both the records clearly show that sea level is rising in Sydney, and that the rate of the rise is increasing. However, the 20th-century rate in Sydney is about 0.8 mm/yr, which is smaller than the global mean of ~1.4 mm/yr. There are many processes that cause sea level to rise at different rates over the globe. For Sydney, one of the processes that cause a below-average rate of sea level is Glacial Isostatic Adjustment. During the last glacial cycle, large parts of the Earth were covered by thick ice sheets, often more than a kilometer thick. The solid Earth below these ice sheets deformed under this load. Eventually, these ice sheets have melted, but the Earth is still recovering from these loads, which still causes the Earth’s shape to change. For Sydney, this means that the Earth is lifting up by about 0.3 mm/yr[2], which could explain a part of the difference. Long story short: from these pictures, one cannot conclude that sea level in Sydney has risen by 0.0 cm. In fact, two independent tide gauge records show that sea level in Sydney has risen by about 12 cm since the end of the 19th century."
https://science.feedback.org/review/telegraph-article-misleads-with-false-balance-mixing-in-unsupported-and-inaccurate-claims-sarah-knapton/,-1.7,"The Telegraph, by Sarah Knapton, on 2019-10-15.",,"""Climate change: fake news or global threat? This is the science""",,,,,"This article in The Telegraph attempts to discuss the science of observed global warming and the factors responsible. However, mixed in with some accurate factual statements are claims that give readers the impression that the answers are unknown, and climate science is “up for debate”. For example, the article presents the views of one person who claims carbon dioxide has little to do with temperature change, pointing instead to water vapor. Several sentences following this note that water vapor in the atmosphere is controlled by temperature, and so cannot drive a warming trend. However, this is framed as “one scientist says” vs. “some other scientists say”, creating the appearance of scientific debate that doesn’t exist. So even though the article includes some accurate quotes from climate scientists, overall it elevates many inaccurate claims that are not supported by evidence—like claiming that scientists “have misrepresented the data in the past” or that “solar activity is more likely to influence today’s climate than carbon dioxide”.See all the scientists’ annotations in context. You can also install the Hypothesis browser extension to read the scientists’ annotations in context.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: This article is a prime example of false equivalence, putting fringe figures side by side with mainstream scientific findings while failing to distinguish between their respective credibility. It is rife with numerous factual errors and misrepresentations. Anyone unfortunate enough to read it will understand less of the science – as actually appears in peer-reviewed publications and conferences – not more. Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: While this article contains good science and accurate quotes from relevant experts, it also suffers from many inaccuracies and misleading statements. The author misleadingly presents a “he said, she said” comparison of well-established science and fringe denier memes that have been thoroughly debunked many times before. This creates a sense of false balance and doubt in the reader which is not present in the scientific literature. Peter Thorne Professor, Maynooth University: The article includes many scientifically relevant observations (e.g. that the world is warming and that humans are responsible) and includes a number of relevant quotes from respected scientists. But then it places this cheek-to-jowl with long-rebutted arguments and assertions that serve to significantly reduce its credibility. Dredging up long-rebutted talking points and presenting them alongside established scientific knowledge uncritically is not helping to inform the reader. Ed Hawkins Principal Research Fellow, National Centre for Atmospheric Science: The article is full of misleading statements, inaccurate assumptions, and interpretations, and is of very low credibility overall. Some simple fact-checking with climate science experts would have easily avoided the errors being made. Where the author has interviewed climate science experts then the science is presented accurately by those experts. Irene Brox Nilsen Researcher, Norwegian Water Resources and Energy Directorate: The article re-iterates many refuted misconceptions about climate change. For example, claiming that “the only thing CO2 does in the climate system is make the planet greener”. This does not apply to the whole climate system; for regions experiencing drying, plant growth will be limited by the availability of water1. Second, results are taken out of context and/or written in an ambiguous way. For example: “[Sea level rise] is projected to rise another one to four by 2100”. No unit is stated here, but because the previous sentence gave numbers in inches, one would think the sea level is projected to rise 1-4 inches, instead of 1-4 FEET, which is the case according to SROCC2. 1- Wramneby et al (2010) Hot spots of vegetation‐climate feedbacks under future greenhouse forcing in Europe, Journal of Geophysical Research: Atmospheres 2- IPCC (2019) Special Report on the Ocean and Cryosphere in a Changing Climate Victor Venema Scientist, University of Bonn, Germany: This Telegraph article mixes sections accurately reporting on the science with sections describing bizarre claims and smears from the darkest corners of the internet as if they were a valuable part of a scientific debate. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Annotations: The statements quoted below are from the article; comments are from the reviewers (and are lightly edited for clarity). can today’s climate models be trusted when scientists have misrepresented the data in the past? Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: A strangely (deliberately?) vague swipe at climate science. The author presents no evidence that scientists have intentionally misrepresented “the data” in the past, or which data this refers to (either here, or later in the article). The planet’s average ground temperature has risen by around 1.62F (0.9C) Peter Thorne Professor, Maynooth University: The latest estimates would place this closer to 1 degree C. Mainly as a result of the run of recent warm years. global temperatures have risen between 0.23F (0.13C) and 0.34F (0.19C) per decade Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: This is conflating temperatures at the surface with temperatures 2 miles up in the lower troposphere, which are very different things. Surface temperature records from NASA, NOAA, Hadley, Berkeley Earth, Cowtan and Way, and Copernicus have trends ranging from 0.17C to 0.21C per decade between 1990 and 2018. The two lower tropospheric records, UAH and RSS, have trends of 0.13C and 0.22C per decade, respectively. However the warming trend is slower than most climate models have forecast Peter Thorne Professor, Maynooth University: This is demonstrably untrue. Firstly, the models from the early 1990s have proven remarkably correct in predicting how surface temperatures have subsequently evolved. But, more prescient is to look at current models. The ability of climate models when run with historical changes in important forcings through 2004 and then on to present with a plausible scenario is impressive. The single realisation that is the real-world clearly sits well within the spread of solutions predicted by the models. (See e.g.) Updated comparison of simulations of past climate (CMIP5) with observed global temperatures (HadCRUT4) up to and including 2018. pic.twitter.com/B96pURwOa2 — Gareth S Jones (@GarethSJones1) February 8, 2019 Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: This is generally not accurate. When we looked at past climate model forecasts, most were pretty close to what was actually observed. See my Carbon Brief article on the subject for details. Here is a comparison between observations and the climate models featured in the last IPCC assessment report (CMIP5). Observations are well within the envelope of model projections and, in recent years, are quite close to the multimodel mean: In 1990 the United Nation’s Intergovernmental Panel on Climate Change (IPCC) predicted that temperatures would rise by 0.54F (0.3C) per decade. Skeptics argue that the forecasts were too high because they relied too heavily on the impact of carbon dioxide (CO2). Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: The IPCC First Assessment Report projected surface temperature changes of around 0.26C per decade between 1990 and 2017. This compares to observed temperature changes of around 0.19C over the same period. However, the first IPCC report projected that the radiative forcing from greenhouse gases would increase around 55% faster than was actually observed. We can’t expect modelers to have a crystal ball to predict future emissions; indeed, even a perfect physics-based model of the Earth’s climate would produce incorrect results if you get future emissions 50% off. When this mismatch is taken into account, the IPCC First Assessment Report projections are nearly identical to observations. Yet, some scientists argue that the gas is not capable of producing the extreme temperature rises seen in recent decades. Victor Venema Scientist, University of Bonn, Germany: In the same way some “scientists” claim quantum mechanics is wrong. Single scientists are not a source of reliable scientific information, especially after searching them out for holding views that reject the scientific understanding of the world. Normally the reporting in the science section of a reputable newspaper would be based on the overwhelming evidence presented in high quality peer reviewed scientific journals. In its 5th assessment report in 2013, the IPCC estimated that human emissions are probably responsible for more than half of the observed increase in global average temperature from 1951 to 2010. But it means a chunk of the rise is coming from elsewhere. Peter Thorne Professor, Maynooth University: This is a gross misrepresentation of the assessment. The relevant finding is: “It is extremely likely that more than half of the observed increase in global average surface temperature from 1951 to 2010 was caused by the anthropogenic increase in greenhouse gas concentrations and other anthropogenic forcings together. The best estimate of the human-induced contribution to warming is similar to the observed warming over this period.” (My italicisation.) The reporter has picked up a commonly used trick to quote just the first sentence of the key finding. The full finding clearly falsifies the assertion here. The best estimate remains that all the warming seen since the mid-20th Century is down to us. Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: This is deceptive. Most published work suggests human activities are responsible for all, if not more than 100% of observed warming. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: In its 2013 fifth assessment report, the IPCC stated in its summary for policymakers that it is “extremely likely that more than half of the observed increase in global average surface temperature” from 1951 to 2010 was caused by human activity. By “extremely likely”, it meant that there was between a 95% and 100% probability that more than half of modern warming was due to humans. This somewhat convoluted statement has been often misinterpreted as implying that the human responsibility for modern warming lies somewhere between 50% and 100%. In fact, as NASA’s Dr. Gavin Schmidt has pointed out, the IPCC’s implied best guess was that humans were responsible for around 110% of observed warming (ranging from 72% to 146%), with natural factors in isolation leading to a slight cooling over the past 50 years. For more details, see my Carbon Brief explainer on why the best-estimate of the human contribution is around 100% of observed warming. Even ExxonMobil’s own scientists predicted in 1982 that the increase in greenhouse gas concentrations and warming we would see by now if we the world did not curtail fossil fuel burning. [sic]Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: And, critically, they were largely correct! at the end of recent ice ages, the concentration of carbon dioxide in the atmosphere started to rise only after temperatures began to climb. Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: This is misleading. The way it is written incorrectly suggests that warming simply causes an increase in atmospheric CO2. The author has not acknowledged the positive feedback whereby as the Earth warms, the ocean releases more carbon to the atmosphere, reinforcing the warming. There is also methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons and sulphur hexafluoride. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: All of which have had their atmospheric concentrations dramatically increased by human emissions, similar to CO2. But by far the largest greenhouse gas is water vapour, which makes 95 per cent of the total. Peter Thorne Professor, Maynooth University: But water vapour is a feedback and not a long-term forcing. The amount of water vapour in the atmosphere is driven by the temperature (for every 1K increase 7% more water can be held) and water has too short lifetime in the atmosphere (think precipitation). Scientists such as Dr Willie Soon, a solar astrophysicist at the Harvard-Smithsonian Center for Astrophysics, have shown that as water vapour rises, so does temperature. It is why cloudless nights are so chilly. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: The water vapor feedback is one of the main positive feedbacks in the climate system. It has been well understood for much of the century that increased temperatures will increase the amount of water vapor in the atmosphere, trapping additional heat. This is by no means a controversial topic in the scientific community, fringe views by Willie Soon notwithstanding. Water vapor cannot be a forcing because of its extremely short atmospheric lifetime in the troposphere. Adding a bunch of additional water vapor won’t cause long-term changes, as it will quickly precipitate out. However, the absolute amount of water vapor in the atmosphere is strongly determined by the temperature; warm the planet (e.g. by increasing CO2 concentrations) and you will end up with more water vapor in the air. This is why water vapor is a feedback rather than a forcing. This RealClimate post provides some good background on the role of water vapor as a climate feedback. Correlation does not equal causation Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: Climate change science is not based on correlation! The physics of the greenhouse effect is well established. Why this quote was included is a mystery. CO2 is not powerful in that sense, the only thing it does in the system is make the planet greener. Irene Brox Nilsen Researcher, Norwegian Water Resources and Energy Directorate: This may be true for certain regions in the mid-latitudes, but it presents a limited view of the Earth system. For regions experiencing drying, plant growth will be limited by the availability of water. Reafforestation at high latitudes (due to a combination of warming and less grazing) changes the albedo, which feeds back to warming the local climate. See for instance Wramneby et al (2010)1: “In the Scandinavian Mountains, reduced albedo resulting from the snow‐masking effect of forest expansion enhanced the winter warming trend. In central Europe, the stimulation of photosynthesis and plant growth by “CO2 fertilization” mitigated warming, through a negative evapotranspiration feedback associated with increased vegetation cover and leaf area index. In southern Europe, increased summer dryness restricted plant growth and survival, causing a positive warming feedback through reduced evapotranspiration.” (abstract) 1- Wramneby et al (2010) Hot spots of vegetation‐climate feedbacks under future greenhouse forcing in Europe, Journal of Geophysical Research: Atmospheres Carbon Dioxide is playing a minor role in the total greenhouse effect. Peter Thorne Professor, Maynooth University: Carbon dioxide is the major contributor to changes in long-lived climate forcers since the industrial revolution.Dr Willie Soon’s comparison of temperature data and water vapour [Figure] Peter Thorne Professor, Maynooth University: This follows the physical expectation that water vapour scales with temperature. The temperature change is driving the changes in water vapour (maintaining quasi-constant relative humidity) and not vice-versa. So they are correlated but for precisely the opposite reason than is being reported here. Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: After including a quote about correlation not being equivalent to causation, this figure is an odd inclusion as there is no explanation as to its purpose other than to (apparently) illustrate the correlation between water vapour and temperature. Yet other scientists claim this is a red herring because of the positive feedback loop created by water vapour. Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: This entire article is a mess of false equivalency. It is not a case of “some scientists say this, while others say this”. There is the scientific consensus (the so-called 97%) and then there are a few fringe scientists such as Willie Soon who have been comprehensively proven to produce poor work riddled with errors.1 Benestad et al (2015) Learning from mistakes in climate research, Theoretical and Applied Climatology it’s virtually impossible to get funded for work that disputes climate change through other channels [other than oil companies] Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: There are whole academic research programs focused on exploring the role of natural variability on the climate. It’s hard to get funded if your ideas are extremely fringe—e.g. if you argue that CO2 is not a greenhouse gas—but not if you are a legitimate researcher exploring the role of natural factors in the changing climate. Indeed, the whole discipline of paleoclimatology is focused on just that. Even the BBC has admitted to Ofcom that the corporation is now biased on the matter because it no longer thinks there is a counter-argument. Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: In the same way they are biased towards believing the Earth is round, right? Victor Venema Scientist, University of Bonn, Germany: In the same way they are biased towards believing vaccines do not cause autism? Peter Thorne Professor, Maynooth University: The more pernicious issue that pervades media reporting of not just climate change but also many other fields of science and other issues is the false-balance paradigm that this article itself falls foul of repeatedly. One of the main areas of contention is the existence of two strange climate episodes known as The Medieval Warm Period (MWP) and the Little Ice Age. The MWP lasted from about 950 to 1250AD, and temperature records appear to show it was even hotter than today Peter Thorne Professor, Maynooth University: These periods are now well understood to be, at best, regional phenomena rather than global-scale changes. Indeed, it is the broad global nature of the recently observed changes that make them unusual. The realisation of these being largely regional phenomena centred on the N. Atlantic region has led to a growing deprecation of these terms. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: There is little evidence in the academic literature that the Medieval Warm Period was warmer than today in terms of global average temperatures. The PAGES 2k Consortium—a group of dozens of paleoclimate researchers from around the world—found1: “There were no globally synchronous multi-decadal warm or cold intervals that define a worldwide Medieval Warm Period or Little Ice Age, but all reconstructions show generally cold conditions between AD 1580 and 1880, punctuated in some regions by warm decades during the eighteenth century. The transition to these colder conditions occurred earlier in the Arctic, Europe and Asia than in North America or the Southern Hemisphere regions. Recent warming reversed the long-term cooling; during the period AD 1971–2000, the area-weighted average reconstructed temperature was higher than any other time in nearly 1,400 years.” 1- Pages 2k Consortium (2013) Continental-scale temperature variability during the past two millennia, Nature Geoscience Irene Brox Nilsen Researcher, Norwegian Water Resources and Energy Directorate: The author uses a common technique of confusing the climate in single region with the global climate. Statments such as this (or “this winter is so cold, we can call climate change off”) are irrelevant because they do not refer to the global climate. Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: Wrong1. 1- Pages 2k Consortium (2019) Consistent multidecadal variability in global temperature reconstructions and simulations over the Common Era, Nature Geoscience But the period has caused a headache for climate scientists because clearly there was no upswell in carbon dioxide that could account for such swift warming. Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: The author fails to mention that we have solid hypotheses for the mechanisms behind both the MWP and LIA that are independent of CO2 forcing, such as changes in solar activity and volcanism. Secondly, it’s foolish to suggest that just because carbon emissions today are the dominant climate forcing, that this must be true at all times in history.frost fairs were held on the Thames when the river froze Peter Thorne Professor, Maynooth University: The cessation of these frost fairs was linked to changes in river management and not to climate change. Skeptics claim such anomalies prove that Earth can quickly warm and cool even in the absence of carbon dioxide, and any warming today may be caused by similar natural events. Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: And climate scientists would agree—a large volcanic eruption will quickly (albeit temporarily) cool the Earth. Critically, there is zero evidence that present day warming is caused by anything other than human activity. Peter Thorne Professor, Maynooth University: Historical variations are well understood to have been caused by changes in solar output, orbital variations, volcanoes and on geological timescales changes in carbon dioxide and continental configuration. None of this remotely disproves the very robust evidence that recent changes are driven almost entirely by our historical emissions of greenhouse gases. in 1995 one scientist at the IPCC – Jonathan Overpeck – wrote an email to a colleague claiming ‘we have to get rid of the Medieval Warm Period.’ Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: While David Deming has made this claim many times in the past, there is no evidence that Overpeck actually ever said this. Victor Venema Scientist, University of Bonn, Germany: I challenge the author to find a source for this smear that satisfies journalistic standards. The ‘hockey stick’ graph [Figure]Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: This is a recent composite figure showing the modern PAGES2K reconstruction (in green) on top of the original MBH ’98 hockey stick graph. If the author was trying to criticize the original figure, showing a modern reconstruction that largely agrees with it is a rather odd choice. it later emerged that its creator Dr Michael Mann had spliced too [sic] datasets together – tree-rings showing temperatures going back hundreds of years, then recent thermometer readings for the more recent decades.Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: This statement is false. Mann never spliced together thermometer readings and paleoclimate proxy records in his 1998 paper. Both were shown on the same graph, but were clearly marked as separate series. Similarly, the author’s claim that Mann’s paleoclimate record was purely based on tree rings is inaccurate. Experts argued that tree-ring data is a hopelessly flawed measure of climate as yearly growth is not just based on temperature but also rainfall, pests, and nutrients in soil. Canadian geologist, Stephen McIntyre discovered[…] Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: There is a worthy discussion to be had on proxy-signal stationarity and the subsequent quality of the climate signal, but then why did the author not consult a dendrochronologist rather than a geologist? The IPCC no longer includes the ‘Hockey stick’ chart in its reports. Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: Completely untrue. AR5 includes several paleoreconstructions of temperature over the last 2,000 years, including those of Michael Mann. Peter Thorne Professor, Maynooth University: Not only does IPCC include a whole family of such estimates but these estimates are now based upon many more sources of data from many more regions of the world. This assertion is verifiably false. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: The latest IPCC report includes a whole family of hockey sticks by a number of different research groups. Since the original Mann paper our understanding of paleoclimate changes has grown dramatically, but the overall picture shows recent warming as unprecedented at least over the past 2,000 years: Irene Brox Nilsen Researcher, Norwegian Water Resources and Energy Directorate: This argument was refuted in 2006: “The fact is there are dozens of other reconstructions. These other reconstructions do tend to show some more variability than MBH98 (the handle of the hockey stick is not as straight), but they all support the general conclusions that the IPCC TAR presented in 2001: the late 20th century warming is anomalous in the last one or two thousand years and the 1990’s are very likely warmer than any other time in the last one or two thousand years.” Yet a study published just this week, by the Bjerknes Centre for Climate Research in Bergen, Norway, found that the natural climate system can change abruptly, without the need for any external forces. Peter Thorne Professor, Maynooth University: This falls foul of the single study fallacy. The basis for our understanding is a holistic assessment of multiple lines of evidence. It would take a spectacular new finding to overturn the enormous and compelling body of evidence that underlies our understanding. Andrew Shepherd Professor, University of Leeds: The study in question is a regional one—on Arctic glaciers—so is entirely consistent with what has already been explained and not an example to the contrary as the opener “Yet” implies. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: Its unclear what study they are referring to here, as they only link to the front page of the Bjerknes Centre. Ironically, the story currently there states that: “A warm period is occurring across the whole world for the first time in at least 2000 years. The cold and warm climatic phases of the past 2000 years were not, as previously assumed, global phenomena. The climate varied greatly from region to region. That’s according to a study by the University of Bern that has just been published in Nature. In contrast to earlier times, current, anthropogenic climate change is occurring across the whole world at the same time.” Some scientists believe that solar activity is more likely to influence today’s climate than carbon dioxide, and Dr Soon has compiled data showing temperature in America, Canada and Mexico rises and falls in line with solar activity.Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: This is a very fringe view in the scientific community. The fact that Soon is cherry-picking three regions instead of looking at global temperatures is a clear sign of the weakness of his argument. He is also using a quite outdated solar irradiance estimate at odds with modern solar research. There is a weak relationship between changes in solar output and global temperatures in the historical temperature record. In fact, the amount of solar energy reaching the Earth has slightly declined since 1970 during the period over which we’ve seen rapid global warming. The figure below shows global temperatures and solar irradiance over the century: Source: NASA We also see a strong anthropogenic fingerprint of warming: the troposphere is warming while the stratosphere is cooling.See my Carbon Brief post on the subject for details. Andrew Shepherd Professor, University of Leeds: Soon’s minority views on sunspots being responsible for global warming are juxtaposed against those of the IPCC that it is not. Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: Once again, after decrying the misuse of correlations earlier in the article, Willie Soon presents nothing more than the covariance of solar irradiance and temperature in one region. Peter Thorne Professor, Maynooth University: Firstly, the correlation isn’t particularly compelling. But secondly, why choose daily high temperature over Mexico? It smacks of a very spectacular cherry-pick. Searching over enough regions and metrics and playing the wiggle matching game, one could likely create similarly impressive graphs for any posited mechanism somewhere on Earth. But that doesn’t mean that there is a meaningful link between the two. Predictions by some scientists that the Arctic would be entirely ice free by 2016 have proven too alarmist Andrew Shepherd Professor, University of Leeds: The “predictions by some scientists” were again personal statements and not the model predictions of the time; even then the experiments done by IPCC suggested mid-century. Today the ice is melting at such a dramatic rate that large shipping companies are considering expanding their routes to the top of the world.Peter Thorne Professor, Maynooth University: Not just large ships. Sailing ships have now circumnavigated the pole in one summer season where once there was perennial multi-year ice Extreme cases of ice melting typically occur once every 250 years Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: Citation? I’m not aware of any such multi-centennial cycle in Arctic sea ice. Andrew Shepherd Professor, University of Leeds: This statement is incorrect; ice cores show that the rapid ice melting in Greenland today is unprecedented in at least the past 350 years1, and when compared to the marine geological record, the rapid ice sheet retreat that is happening in West Antarctica is unprecedented in the present glacial cycle (over 10,000 years)2. 1- Trusel et al (2018) Nonlinear rise in Greenland runoff in response to post-industrial Arctic warming, Nature 2- Konrad et al (2018) Net retreat of Antarctic glacier grounding lines, Nature Geoscience The melting ice has led to global sea level rise of around eight inches since reliable record keeping began in 1880. Irene Brox Nilsen Researcher, Norwegian Water Resources and Energy Directorate: This is correct. IPCC’s special report on Ocean and Cryosphere1 reports an increase of about 16 cm (6.2 in) for the period 1901–1990 and an increase of about 4 cm (1.6 in) for the period 2005–2015, page 4-3: “GMSL from tide gauges and altimetry observations increased from 1.4 mm yr–1 over the period 1901–1990 to 2.1 mm yr–1 over the period 1970-2015 to 3.2 mm yr–1 over the period 1993–2015 to 3.6 mm yr–1 over the period 2005–2015 (high confidence)” 1- IPCC (2019) Special Report on the Ocean and Cryosphere in a Changing Climate It is projected to rise another one to four by 2100. Peter Thorne Professor, Maynooth University: It is projected to rise by 1 to 4 feet, not 1 to 4 inches as implied here. That’s an order of magnitude error. Irene Brox Nilsen Researcher, Norwegian Water Resources and Energy Directorate: IPCC’s special report on Ocean and Cryosphere1 reports projected increases in sea level rise between 17 inches (43 cm) and 33 inches (84 cm). SROCC, page 4-4: “GMSL will rise between 0.43 m (0.29–0.59 m, likely range) (RCP2.6) and 0.84 m (0.61–1.10 m, likely range) (RCP8.5) by 2100 (medium confidence) relative to 1986-2005.” 1- IPCC (2019) Special Report on the Ocean and Cryosphere in a Changing Climate Methane can also raise the acidity of the water and kill off sea creatures as it breaks down. Victor Venema Scientist, University of Bonn, Germany: It does that after breaking down to CO2. It wasn’t until the 1970s that satellites picked up the El Niño Southern Oscillation cycle (ENSO) on a global scale. Peter Thorne Professor, Maynooth University: It wasn’t until the 1970s that satellites picked up anything as there were few to no satellites. But understanding of ENSO has been accruing for at least a century using direct measurements of sea surface temperatures and surface atmospheric pressure. Thus this is misleading. until temperature increases began to slow down after 1998 and remained relatively stable for a period of 15 years Victor Venema Scientist, University of Bonn, Germany: There is no bigger statistical sin than starting the computation of a trend in a year selected because it has a huge peak. All the theory needed to compute the uncertainty of such a trend estimate goes out of the window if you do that. I wish the reader luck finding this “hiatus” in the global temperature series below. It is normal variability around a warming trend. SourceToday, the hiatus is still disputed as it is picked up in the Met Office’s compilation of global temperatures but not in the records compiled by the National Oceanic and Atmospheric Administration (NOAA) and Nasa. Peter Thorne Professor, Maynooth University: There is no justification for this statement. The datasets are too similar to one another to justify such an assertion. The difference is probably due to the way in which these different groups calculate a global average from the worldwide network of weather stations.Peter Thorne Professor, Maynooth University: The major differences between the datasets tend to arise over the oceans and not the land. Adjustments and manipulations Victor Venema Scientist, University of Bonn, Germany: No evidence given for this conspiracy of science against humanity. Conspiracies tend to involve small groups of people working in seclusion on a limited task, not an open group of scientists working on a problem for decades with thousands of scientists all over the world. Contents of the emails suggested scientists had been hiding or manipulating data, preventing people accessing their figures and working to stop papers critical of their findings from being published.Peter Thorne Professor, Maynooth University: These assertions have long been rebutted and yet this is not even alluded to. In one particularly damning email, CRU director Phil Jones said he had used ‘Mike’s Nature trick’ to ‘hide the decline’ in temperatures in the second half of the 20th century. Just like Dr Mann’s ‘hockey stick’ graph he had cut off the tree-ring data just at the point where it stopped showing an upward trend and swapped in thermometer temperatures for recent decades, making them look much warmer. Peter Thorne Professor, Maynooth University: There was and still is good reason to do this scientifically and it is not a “trick”, it is a method which has passed peer-review. In an interview with the BBC after the scandal broke, Dr Jones admitted there had been no statistically significant global warming since 1995 Peter Thorne Professor, Maynooth University: Statistically significant change over any 15 year period in the presence of substantial autocorrelation and year-to-year variability would always be unlikely. The panel was forced to retract a statement in its 2007 report saying all Himalayan glaciers could melt entirely by 2035. Peter Thorne Professor, Maynooth University: The article fails to make clear that this was in an underlying chapter of the impacts and adaptation report and not elevated to the summary for policymakers. It later emerged that many of the alarming claims cited in IPCC reports were not based on science but press releases and unfounded reports made by climate activists Peter Thorne Professor, Maynooth University: The article fails to clarify again the context of where and how these were used. Specifically, they tend to be used in the impacts, adaptation and mitigation reports where regional detail is required and there is often a paucity of peer-reviewed literature. The figure traditionally cited that suggests 97 per cent of climate scientists agree that global warming is man-made was also found to be flawed. A survey which claimed to have questioned 10,257 academics, was found to have winnowed down the sample to just 77. Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: Completely deceptive. Multiple studies have reinforced the scientific consensus on the human impact on global warming. A poll of 1854 members of the American Meteorological Society found the number who believe climate change to be man-made to be 52 per cent. Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: Why mention a poll in which only 13% of respondents were climate scientists and not the several other peer-reviewed studies that support the consensus figure? Climate skeptics argue temperature records have been adjusted in recent years to make the past appear cooler and the present warmer, although the Carbon Brief showed that NOAA has actually made the past warmer, evening out the difference.Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: As the scientist who made the figure in the text here (included below), I can say this is completely incorrect. There is no “evening out of the difference”. Adjustments to global temperatures make the past warmer, not cooler, mostly due to adjustments to ocean temperature records to account from the transition between bucket and engine room intake valve measurements in ships. Adjustments warm the past, reducing the long-term warming trend compared to the raw data. Adjustments have a relatively minimal impact on global temperature trends since 1950. If scientists were trying to adjust the data to show more warming, we are doing it in the wrong direction! Source: Carbon Brief Victor Venema Scientist, University of Bonn, Germany: As the graph shows, warming estimates are smaller after adjustment. This is the opposite of typical baseless claims by climate “sceptics” and makes the conspiracy theory that scientists are manipulating (in the words of the Telegraph) the data rather counterintuitive. Satellite data from Remote Sensing Systems (RSS) in California initially showed temperatures which largely flatlined from 1998, but that data has since been adjusted to show a warming trend.Peter Thorne Professor, Maynooth University: Satellite data records have been shown to be more uncertain than surface records. All major satellite groups who have created multiple versions have at various times adjusted both up and down their estimates of long-term change. Each update reflects new understanding and improved processing. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: At the same time, satellite data from University of Alabama, Huntsville initially showed temperatures rising fast since 1998, but that data has since been adjusted to show a much lower warming trend. There is large structural uncertainty in satellite temperature records, as evidenced by these large adjustments. Surface temperature records, on the other hand, are much more stable and show larger agreement between the research groups that produce them. For details, see my Carbon Brief article on adjustments to satellite data. The difference between recorded temperatures and reported temperatures has been slowly rising in recent years. Peter Thorne Professor, Maynooth University: This is an unsupported assertion and is ignorant to the true process of dataset creation efforts. Estimates of historical changes have been updated but these updates reflect improved knowledge, improved access to observations, and new observational capabilities. Datasets are subject to peer-review and then subsequent review and feedback on a continuous basis by users. No dataset is ever perfect and it is critically important to encourage continuous re-evaluation to ensure the best possible understanding. Confusion peaked in 2014 when surface temperature readings said the year was the hottest on record, while satellites maintained it was cooler than 1998. Victor Venema Scientist, University of Bonn, Germany: Surface temperature responds less to El Niño than the noisy upper air temperatures. As 1998 was a year with a very strong influence of El Niño, it makes sense that the peak was higher for upper air temperatures than for surface temperatures. Although it might appear scientists are ‘cooking the books’, experts say the shifts are necessary to avoid biases from station relocations, instrument changes, the time of day and the heat island effect.Peter Thorne Professor, Maynooth University: Misleading in that the major differences arise in treatment of ocean and not land based records. These are done to ensure that temperature measurements can be compared over time Victor Venema Scientist, University of Bonn, Germany: I work on algorithms to make temperature measurements made over the centuries comparable with each other to make trend estimate more reliable. For people interested in the why and how, I wrote a primer. When the measuring equipment gets old and needs replacing, it often requires re-calibration. Victor Venema Scientist, University of Bonn, Germany: Also, new equipment is regularly calibrated. UPDATES: 18 October 2019: Several comments by Andrew Shepherd were received and added after the initial publication of this post."
https://science.feedback.org/review/letter-signed-by-500-scientists-relies-on-inaccurate-claims-about-climate-science/,-1.8,"Clintel, by Ingemar Nordin, Viv Forbes, Terry Dunleavy, Rob Lemeire, Richard Lindzen, Reynald du Berger, Morten Jodal, Jim O'Brien, Jeffrey Fos, Guus Berkhout, Fritz Vahrenholt, Christopher Monckton, Benoit Rittaud, Alberto Prestininzi, on 2019-09-23.",,"""There is no climate emergency""",,,,,"This letter presenting a short list of claims about climate change boasts a list of “500 scientists and professionals” who have co-signed it. The claims contradict or misrepresent the evidence uncovered by geoscientists, failing to provide support for its conclusions downplaying the threat of climate change.The letter claims, for example, that climate models ignore the benefits of increased CO2 on plant growth. This is false, as many climate models simulate the response of vegetation to increased CO2—and the climate change it causes. And while some outlets described the co-signers as experts in climate science, most are not. As noted in an analysis below, a significant portion of the co-signers are either engineers or professionals in non-technical fields. Only 10 identified themselves as climate scientists. Similar letters have sought to establish credibility with large numbers of co-signers in the past, but evidence is what counts in science.See all the scientists’ annotations in context. You can also install the Hypothesis browser extension to read the scientists’ annotations in context. REVIEWERS’ OVERALL FEEDBACK: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Timothy Osborn Professor, University of East Anglia, and Director of Research, Climatic Research Unit: This statement is unscientific. It ignores well-established understanding of climate and of what causes the climate to change. It makes cherry-picked statements, such as noting that some vegetation grows more with increased CO2 while ignoring the risks of serious damage arising from the climate change that is being caused by the same increase in CO2. The authors of the statement appear to be very unfamiliar with climate science: for example, they do not know that the amount of global warming we have observed is very close to the amount predicted by climate models. Twila Moon Research Scientist, University of Colorado, Boulder: The letter contains direct lies and cherry picks information about carbon dioxide and climate change impacts that are designed to mislead. I am also concerned that many of those who have signed the letter are well known climate deniers and are not actively involved in direct research on climate change and its impacts. Victor Venema Scientist, University of Bonn, Germany: The text is a masterpiece: next to the political opinions expressed, every single sentence is either wrong, insignificant or irrelevant for the question whether climate change is a serious problem for humanity. Given how old the “arguments” are, the authors are clearly not aiming to convince scientists and thus making science more political, while disingenuously claiming to be against that. Amber Kerr Researcher, Agricultural Sustainability Institute, University of California, Davis: Each of the six claims has some element of truth to it (e.g. there is not much evidence that global warming is already making hurricanes more frequent). However, all six claims are presented in a biased and misleading way, giving the incorrect impression that anthropogenic climate change is a benign or beneficial force overall, whereas scientists and economists have repeatedly concluded that climate change is a massive and urgent problem. Giorgio Vacchiano Assistant Professor, Università di Milano: The scientific content is completely inaccurate, undocumented, and fails to bring proof for its claims. The ending of the Little Ice Age in 1850 has no logical link with the fact that the Earth is warming now. Most past climate variations have been slower or less intense as the present one, and if they were as fast or severe they brought about mass extinctions in the biosphere. No explanation or proof is brought on the implausibility or inaccuracy of climate models (whose accuracy or uncertainty is precisely quantified and makes their use better than just random guesses). The last two statements are based on literature and common knowledge, but qualify as cherry-picking because they omit most negative effects of CO2 increase and warming (e.g. other clear trends in extreme events, damage to forests and crops by drought and heat waves). Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Annotations: The statements quoted below are from the article; comments are from the reviewers (and are lightly edited for clarity). A global network of 500 scientists and professionals has prepared this urgent message. Amber Kerr Researcher, Agricultural Sustainability Institute, University of California, Davis: While reviewing the claims related to agriculture, I noted that only 26 out of the 506 signatories (5%) were professionals in biology, ecology, or environmental science. I suspect that the vast majority of signatories had little direct knowledge or understanding of this part of the petition that they signed. This made me curious to delve more deeply into the makeup of the signatory list. I usually try to steer clear of any ad hominem tactics, and instead evaluate claims solely on their own merits. However, the fact that this group is vocally promoting themselves as “knowledgeable and experienced scientists and professionals in climate and related fields” made me wonder if that claim is actually supported by the signatories’ credentials. In a word, the answer is no. The most prevalent groups of signatories were geologists (19%) and engineers (21%)—many of whom were implicitly or explicitly involved in fossil energy extraction. Most of the rest were physicists, chemists, and mathematicians. A large fraction of the signatories were not scientists, but rather business executives, writers, activists, and lobbyists (totaling 11.3%). I also noticed a peculiar omission in the list of signatories: women. Among the 506 names, only 24 were female names (with another 15 that were initials-only or unisex). That means that about 95% of the signers were men. Even for male-heavy fields such as geology and engineering, this is a staggering imbalance. I suspect that the imbalance may have been heightened by the fact that the signers skewed heavily toward the older generation – for example, there were 79 emeritus professors on the list (16% of the total). Again, I’d prefer to evaluate claims on their own merits. But if the ECD group is going to tout their own credentials, then it needs to be pointed out that a large fraction of their 506 signatories have credentials like “Peter Champness, Radiologist, Australia”; “Patrick Mellett, architect and CEO”; and “Fintan Ryan, Retired Senior Airline Captain” (to say nothing of the dozens and dozens of fossil fuel employees). The geological archive reveals that Earth’s climate has varied as long as the planet has existed, with natural cold and warm phases. Victor Venema Scientist, University of Bonn, Germany: That demonstrates that the climate can change. Those past changes also provide science with many independent ways to estimate how much the climate will change due to human emissions of greenhouse gases. Just like people dying naturally is no reason to acquit a murder suspect, the recent warming of the Earth is basically all due to our activities and will only change if we change them. Source: IPCC Twila Moon Research Scientist, University of Colorado, Boulder: It is accurate that the Earth’s climate has experienced natural variability including warm and cold phases. However, the crux is that these changes have NOT happened with human populations at a level even remotely approaching today’s population and development levels. The world population reached 1 billion in ~1800 (link) and climate within the 1000-800 years-before-present timescale was quite stable. Human populations, economies, infrastructure, development have formed during a period of climate stability. The Little Ice Age ended as recently as 1850. Therefore, it is no surprise that we now are experiencing a period of warming Timothy Osborn Professor, University of East Anglia, and Director of Research, Climatic Research Unit: The current period of warming is not because the Little Ice Age ended by 1850. Climate scientists study the causes of warming and cooling period and calculate their effects on our climate. These studies show that natural warming after the Little Ice Age was complete by the late 1800s. The warming from the late 1800s to the present is all due to human-caused climate change, because natural factors have changed little since then and even would have caused a slight cooling over the last 70 years rather than the warming we have observed. See Figures 3b and 6c of Tett et al (2007)1 for example. 1-Tett et al (2007) The impact of natural and anthropogenic forcings on climate and hydrology since 1550, Climate Dynamics Only very few peer-reviewed papers even go so far as to say that recent warming is chiefly anthropogenic. Mitch Lyle Professor, Sr. Research, Oregon State University: This is a gross untruth. Most papers on climate change do not state that recent warming is chiefly anthropogenic because the anthropogenic driver is noncontroversial. Most papers are trying to document how fast change is happening and how it compares to model expectations for fossil-fuel driven global warming. Twila Moon Research Scientist, University of Colorado, Boulder: As noted, this is false. The role of humans is well established, and has been for a number of decades. An example of what the climate would look like without anthropogenic forcing is available in this IPCC figure. Source: IPCC Warming is far slower than predicted. The world has warmed at less than half the originally-predicted rate, and at less than half the rate to be expected on the basis of net anthropogenic forcing and radiative imbalance. Timothy Osborn Professor, University of East Anglia, and Director of Research, Climatic Research Unit: This statement is at odds with comparisons between the warming we have observed and the warming predicted by climate models. These comparisons show good agreement and do not support the claim that warming is far slower than predicted. That the authors of this statement do not know about these published model-data comparisons has led them to make these false statements. For an example of the agreement between observed and predicted warming, see Fig. 4b of Cowtan et al (2015)1 1-Cowtan et al (2015) Robust comparison of climate models with observations using blended land air and ocean sea surface temperatures, Geophysical Research Letters Mitch Lyle Professor, Sr. Research, Oregon State University: The rate is very similar to the projections made by Hansen et al (1988)1. For readers’ information, the largest uncertainty about how the climate will change is how humans will emit in the future. 1- Hansen et al (1988) Global climate changes as forecast by Goddard Institute for Space Studies three‐dimensional model, Journal of Geophysical Research-Atmospheres Victor Venema Scientist, University of Bonn, Germany: The estimates for how much the world will warm due to a doubling of the concentration of carbon dioxide have hardly changed for decades. we are far from understanding climate change Twila Moon Research Scientist, University of Colorado, Boulder: In fact, the basic chemistry and physics of climate change and the greenhouse effect have been well understood for more than a century. Here are a few of those milestones: 1859 – John Tyndall discovers that some gases block infrared radiation. He suggests that changes in the concentration of the gases could bring climate change. 1896 – Svante Arrhenius publishes first calculation of global warming from human emissions of CO2: doubling the CO2 in the atmosphere would raise global temp some 5-6°C (9-11°F) 1897 – Thomas Chamberlin produces a model for global carbon exchange including feedbacks. 1938 – Guy Callendar argues that CO2 greenhouse global warming is underway, reviving interest in the question. 1960s – Charles Keeling accurately measures CO2 in the Earth’s atmosphere and detects an annual rise. The level is 315 ppm. Suki Manabe and Richard Wetherald make a convincing calculation that doubling CO2 would raise world temperatures a couple of degrees. 1977 – Scientific opinion tends to converge on global warming, not cooling, as the chief climate risk in the next century. In addition, [climate models] ignore the fact that enriching the atmosphere with CO2 is beneficial Timothy Osborn Professor, University of East Anglia, and Director of Research, Climatic Research Unit: This statement is wrong: climate models do include the carbon cycle, too (they are then called Earth system models) and these include the effects of increased atmospheric CO2 on vegetation. That the authors of this report do not even know that these effects are included in climate models illustrates how little they really know about climate science. For evidence that CO2 influences are indeed included in IPCC science and projections see e.g. Box 6.4 (“many models now have an interactive carbon cycle”) and Box 6.3 (“The Carbon Dioxide Fertilisation Effect… Elevated atmospheric CO2 concentrations lead to higher leaf photosynthesis and reduced canopy transpiration, which in turn lead to increased plant water use efficiency and reduced fluxes of surface latent heat. The increase in leaf photosynthesis with rising CO2, the so-called CO2 fertilisation effect, plays a dominant role in terrestrial biogeochemical models…”) of IPCC’s Fifth Assessment Report1. 1-IPCC (2013) Climate Change 2013: The Physical Science Basis Mitch Lyle Professor, Sr. Research, Oregon State University: CO2 can be beneficial where plants are water stressed, by preventing loss of water, and in places that are now too cold for growth, like the Arctic. Unfortunately the changes in temperature and water cycle globally will have far more negative effects. CO2 is not a pollutant. Timothy Osborn Professor, University of East Anglia, and Director of Research, Climatic Research Unit: This is only true for a narrow definition of a pollutant. If a pollutant is something that causes adverse effects on natural and human systems, then CO2 is a pollutant when it is increased rapidly in the Earth’s atmosphere and increases the risks of damaging effects. See here for an explanation. Twila Moon Research Scientist, University of Colorado, Boulder: The more important note is that CO2 is a greenhouse gas. Thus, it is able to change the atmosphere’s ability to absorb solar radiation and increase temperatures. [CO2] is essential to all life on Earth. Victor Venema Scientist, University of Bonn, Germany: Nutrients are also essential for life. A farmer can still over-dung their fields. Too much nutrients cause algae blooms and is a major reason for biodiversity losses. The natural CO2 concentration and its natural greenhouse effect are great for life on Earth and keeps the Earth at a pleasant temperature. That does not mean that increasing the CO2 concentration is a good thing. To conclude, this argument makes no sense. More CO2 is beneficial for nature, greening the Earth: additional CO2 in the air has promoted growth in global plant biomass. It is also good for agriculture, increasing the yields of crops worldwide Frances Moore Assistant Professor, University of California Davis: This claim is misleading. In a meta-analysis of over 1,000 studies of the effects of climate change on agriculture[1], we find that, while CO2 is beneficial for crops, this effect rapidly decreases with increasing concentrations. The net effects of climate change on agriculture, including both the benefits of CO2 fertilization and the negative effects of warming, is negative for almost all regions. The effects of CO2 emissions on agriculture cost approximately $8.5 per ton, even accounting for the positive effects of CO2 fertilization. 1- Moore et al (2017) New science of climate change impacts on agriculture implies higher social cost of carbon, Nature Amber Kerr Researcher, Agricultural Sustainability Institute, University of California, Davis: CO2 is not a pollutant in the sense of being acutely toxic to life, but this framing is highly misleading. Water is also non-toxic and essential to life on Earth, but too much water in the wrong places can be devastating. Natural ecosystems The claim that “more CO2 is beneficial for nature” implies that the purpose of nature is simply to produce as much plant biomass as possible, a supposition that would be challenged by every ecologist I know. Dumping a limiting resource into a natural ecosystem is not something to celebrate. In that respect, adding CO2 to the atmosphere is somewhat similar in concept to adding nitrogen and phosphorus to waterways: it stimulates primary production, but it disrupts biogeochemical cycles and species relationships. Although increasing CO2 does tend to stimulate terrestrial plant growth (if you ignore effects of CO2 on temperature and soil moisture), the stimulation is not necessarily a good thing for ecosystems as a whole. CO2 enrichment benefits some plant species while disadvantaging others (due to shifts in competitive dynamics, especially between C3 and C4 plants). Furthermore, plant biomass grown under high CO2 is less digestible, less nutritious, and slower to decompose. Changes in the quality and quantity of plant biomass also have hard-to-predict effects on animal populations, fungal and microbial activity, and soil composition. If only it were as simple as “greening the Earth,” but it’s not. The only silver lining is that, because CO2 does tend to stimulate plant growth, carbon sequestration in plant biomass provides a negative feedback to our CO2 emissions. (This is already accounted for by many models.) But to say that plants help make our CO2 emissions slightly less harmful is not to say that we should be complacent about the emissions in the first place. Agricultural ecosystems Regarding “It is also good for agriculture, increasing the yields of crops worldwide”: There is some truth to this claim, but this description is dangerously oversimplified. First, although controlled studies in the lab, greenhouse, and field do show that CO2 stimulates crop growth and yield, the effect diminishes after several weeks or months of CO2 treatment, once the individual plants acclimate. Many questions still remain about how the “CO2 acclimation effect” works in different species and under different conditions, but it is clear that extrapolating from short-term greenhouse experiments to long-term agricultural production is unwarranted. Second, even aside from the CO2 acclimation effect, it is uncertain how much of the potential gain from CO2 fertilization would be realized in the real world—which not only has other limiting resources such as nitrogen and water, but which would also include higher average temperatures and more extreme events. This is why many scientists who model crop yield under future climate choose not to include the CO2 fertilization effect. (Some choose to report multiple model runs that both do and don’t include the CO2 effect.) Third, and most importantly, the positive and negative effects of climate change on agriculture will not be felt equally around the world. Wealthy temperate regions will not see much harm, and may even see a net benefit, from warmer temperatures and increased CO2. But the opposite will be true of developing regions in the tropics, which do not stand to benefit from warming and will likely suffer from high temperatures and drought. Worldwide, the net effect might be very roughly neutral (probably slightly negative, depending on mitigation and adaptation efforts). But this is not a reason to be complacent, because those who stand to lose the most are also the most vulnerable. In summary, regarding the European Climate Declaration’s claims on plant growth and agriculture, It is both scientifically and ethically indefensible for representatives from wealthy temperate countries to tell the rest of the world that there is nothing to worry about. Timothy Osborn Professor, University of East Anglia, and Director of Research, Climatic Research Unit: This statement is based on selective misuse of evidence. There are benefits of CO2 for vegetation growth (though these benefits are often overstated) but these benefits will likely be limited by nutrient shortage and they may be overcome by changes in climate (e.g. increased drought) caused by the same increases in CO2. For example, IPCC AR5 WGI Chapter 61 reported that “It is very likely… that nutrient shortage will limit the effect of rising atmospheric CO2 on future land carbon sinks”. 1-IPCC (2013) Climate Change 2013: The Physical Science Basis Victor Venema Scientist, University of Bonn, Germany: More leaves is something completely different from beneficial for nature. Twila Moon Research Scientist, University of Colorado, Boulder: Unfortunately, the issue at hand is not isolated to additional CO2 in the atmosphere. Decision makers must address the full suite of changing that occur with climate change, including temperature and precipitation change, nutrient availability, etc. All crops will not respond the same to climate change, but overall global decreases in crop yield and reductions in food security are actually a major concern. This paper1 provides an example of research on the influence of climate change on crop yield. 1-Challinor et al (2014) A meta-analysis of crop yield under climate change and adaptation, Nature Climate Change There is no statistical evidence that global warming is intensifying[…] floods Twila Moon Research Scientist, University of Colorado, Boulder: There is clear evidence that floods due to sea level rise have increased to the present, and are expected to increase more rapidly into the future. Details are available in the new IPCC Special Report on the Ocean and Cryosphere in a Changing Climate. There is no statistical evidence that global warming is intensifying[…] droughts Twila Moon Research Scientist, University of Colorado, Boulder: There have been significant changes in drought, but it has included both increases and decreases. “There is medium confidence that since the 1950s some regions of the world have experienced a trend to more intense and longer droughts, in particular in southern Europe and West Africa, but in some regions droughts have become less frequent, less intense, or shorter, for example, in central North America and northwestern Australia.”1 1-IPCC (2012) Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation CO2-mitigation measures are as damaging as they are costly. For instance, wind turbines kill birds and insects, and palm-oil plantations destroy the biodiversity of the rainforests Mitch Lyle Professor, Sr. Research, Oregon State University: An order of magnitude more birds have been killed by running into buildings and by cats than by wind turbines. This has been debunked for over a decade. There is no climate emergency. Mitch Lyle Professor, Sr. Research, Oregon State University: Temperature change of 0.2 deg C per decade since the 1970s is an emergency. If humans stop emitting CO2 now, it will take another 30 years or so for temperatures to equilibrate with the current atmospheric CO2. We are already seeing significant negative effects, from sea level rise, to floods, to forced human migrations. The effects will only get worse unless we start investing significant effort to stop emitting fossil fuel CO2. we will have ample time to reflect and adapt Twila Moon Research Scientist, University of Colorado, Boulder: This is subjective. But given the scenarios under consideration by the IPCC, they do not suggest that a long delay in action can create the same future result as more immediate action. This can be seen by considering any of the projections that compare RCP2.6, RCP4.5, and RCP8.5."
https://science.feedback.org/review/2c-not-known-point-of-no-return-as-jonathan-franzen-claims-new-yorker/,Incorrect,"The New Yorker, Jonathan Franzen, 2019-09-08",The consensus among scientists and policy-makers is that we’ll pass this point of no return if the global mean temperature rises by more than two degrees Celsius,,"Misleading: While positive feedbacks exist that amplify temperature changes, scientists have not identified a ""point of no return"" at 2°C.","This statement makes a claim about the climate system that does not reflect our best understanding of how it works. The impacts and risks of climate change increase as warming continues, and limiting warming to the 2°C milestone has been chosen as an international goal, but it is not true that scientists expect runaway warming to begin if this milestone is crossed.","Our atmosphere and oceans can absorb only so much heat before climate change, intensified by various feedback loops, spins completely out of control. The consensus among scientists and policy-makers is that we’ll pass this point of no return if the global mean temperature rises by more than two degrees Celsius (maybe a little more, but also maybe a little less)[...] In the long run, it probably makes no difference how badly we overshoot two degrees; once the point of no return is passed, the world will become self-transforming.",,"UPDATE (25 August 2020): This section of the New Yorker article was edited at an unknown date, and now reads: “Some scientists and policymakers fear that we’re in danger of passing this point of no return if the global mean temperature rises by more than two degrees Celsius (maybe more, but also maybe less).” A correction note at the bottom of the article states: “A previous version of this article mischaracterized the scientific consensus around a ‘point of no return.'”Amber Kerr Researcher, Agricultural Sustainability Institute, University of California, Davis: This is not correct. First of all, there is no consensus on what level of warming would be necessary to set off a runaway, exponential greenhouse gas buildup (presumably due to global permafrost melting, methane clathrates disintegrating, and/or continental-scale forest fires). But to the extent that there is a consensus, 2°C is not it. Even a relatively risk-averse assessment of this question, which does recommend trying to limit warming to under 2°C, states that most large-scale destabilizing feedbacks don’t kick in until at least 3°C, and others not until over 5°C1. Second of all, Franzen seems not to realize that climate models already do include feedback loops as a fundamental aspect of climate dynamics. These include water vapor feedback (the most important and least uncertain), ice-albedo feedback, saturation of terrestrial and oceanic carbon sinks, and acceleration of decomposition. The way Franzen discusses feedback loops in his article—as though he is introducing a new insight by including feedback loops as a multiplier on top of climate model output—suggests that he does not understand the details of how climate models work. The second portion of the statement is not only wrong but dangerously misleading. Even apart from the increasing risks of threshold-crossing (per above), it makes a profound difference how badly we overshoot two degrees. Consider the difference between RCP4.5 (an ambitious but realistically achievable scenario in which annual emissions peak in 2040 and go to net zero in 2080) versus RCP8.5 (a do-nothing scenario in which annual emissions are still increasing by 2100). Under RCP4.5, the temperature increase by 2090 is about 2°C, possibly as high as 2.5°C. Under RCP8.5, temperature increase by 2090 is about 4°C, possibly as high as 5°C. All of the following things are credibly predicted to happen under RCP8.5, whereas they would be avoided by RCP4.5: – Large swaths of India may become literally uninhabitable by humans, with sustained wet-bulb temperatures over 35°C2. – Nearly all coral reefs on Earth, including all 29 reefs that are UNESCO World Heritage listed, are likely to experience severe bleaching events annually, leaving them unable to recover3. – Global declines in staple crop production (maize, wheat, rice, soy), not accounting for CO2 fertilization, could be up to 18%, compared to 9% under RCP4.54. These are only three illustrative examples; there are many more. In conclusion, Franzen’s essay shows a lack of understanding of how climate models work. He says that “As a non-scientist, I do my own kind of modelling,” but he seems to be unaware that scientists have already carried out many qualitative and quantitative climate risk assessments, using policy changes and human behavior as variables. His claim that additional warming over 2°C doesn’t matter is scientifically unsound, and his fatalism about human society—though not something that I can assess scientifically—is not a belief that I share. 1- Steffen et al (2018) Trajectories of the Earth System in the Anthropocene, PNAS 2- Im et al (2017) Deadly heat waves projected in the densely populated agricultural regions of South Asia, Science Advances 3- Heron et al (2017) Impacts of Climate Change on World Heritage Coral Reefs : A First Global Scientific Assessment, UNESCO World Heritage Centre 4- Zhao et al (2017) Temperature increase reduces global yields of major crops in four independent estimates, PNAS Charles Koven Staff Scientist, Lawrence Berkeley National Lab: According to our best climate models, which include all of the feedback loops that we can figure out how to put into them, there are not any thresholds beyond which warming will, on its own, spin out of control. It is true that, if the planet reaches higher amounts of warming, then we expect current carbon sinks to weaken and new processes like permafrost thaw to emit greenhouse gases. But at the same time, we also expect that the amount of warming from each additional increment of CO2 that ends up in the atmosphere will weaken as its concentration increases. The surprising result when we couple all of these processes together in models is that these two sets of effects tend to cancel each other out, so that the total amount of warming is roughly proportional to the cumulative amount of CO2 we have emitted. Every bit of carbon that we emit is an extra bit of warming that the planet will experience. The levels of warming that have been set as targets in climate negotiations—like 1.5 or 2 degrees C—are not thresholds beyond which the world will end; they are points where we can try to estimate the impacts and then set as goals that will allow us to avoid some of the worst effects of climate change. If we exceed these goals, then we will certainly experience greater impacts, and there could be surprises that we don’t understand, but there is no reason to expect that warming will become self-sustaining if we fail to keep temperatures below these levels. Patrick Brown Assistant Professor, San Jose State University: There is certainly no consensus among scientists that 2.0°C (3.6°F) global warming above pre-industrial levels represents a “point of no return” for climate change. The dominant feedback in the climate system is the stabilizing feedback known as the Planck Response1 which makes self-perpetuating, run-away warming exceedingly unlikely (at least within the range of temperatures considered under anthropogenic climate change scenarios). There is some speculation that long-term Earth-system feedbacks may become active near 2°C warming2 which would enhance warming to well beyond 2°C in the long run, even without additional anthropogenic greenhouse gas emissions. Nevertheless, we expect the global temperature to depend mostly on cumulative anthropogenic greenhouse gas emissions over the next century and we do not expect to suddenly lose control of the global temperature if the 2°C limit is passed. So what does the 2°C limit mean if it is not a “point of no return”? Two degrees of warming is often thought of as a value after which global warming becomes “dangerous”. The 2°C target was perhaps first made prominent by William Nordhaus in the late 1970s3. He appears to have chosen this amount of warming as it was thought that this might represent the upper boundary of global temperatures that had been experienced during the Holocene Epoch of the past ~10,000 years4. Over the 1980s and 1990s, the conventional wisdom coalesced around 2°C as an amount of warming that should be avoided but there was never a scientific consensus that 2.0°C represented some well-defined bright line where impacts suddenly became much worse or feedbacks suddenly became completely self-perpetuating5. It is perhaps not surprising that it is very difficult to define a single value for “dangerous” warming since the definition of “dangerous” will inevitably depend on the impact being discussed, the geographic location, the timescale, and the risk tolerance. Nevertheless, it is useful to have an official objective to organize mitigation policy around. By 1992, the United Nations Framework Convention on Climate Change adopted the official objective of stabilizing global temperature at a level that would “avoid dangerous anthropogenic interference with the climate system”6 and the 2009 Copenhagen Accord defined this limit to be 2°C7. The 2015 Paris Accord affirmed this 2°C goal but also articulated ambitions for limiting global temperature to 1.5°C8,9. This new ambition for limiting global warming to 1.5°C spurred the IPCC to release a report in late 2018 on the impacts associated with global warming of 1.5°C (2.7°F) above pre-industrial levels as well as the technical feasibility (from an energy systems perspective) of limiting global warming to such a level10. The 2018 IPCC report showed that 1.5°C might be crossed as early as 2030 (12 years after the report was released in 2018) under the current rate of warming. Another important calculation related to 2030 was that in order to avoid 1.5°C in the long run, global CO2 emissions would have to be reduced by 45% by 2030 and reach net zero by 2050. The media coverage of the 2018 IPCC report often reported something to the effect of “The IPCC concluded that we have until 2030 (or 12 years) to avoid catastrophic global warming”. This was not the conclusion of the report11. For one thing, the word “catastrophic” did not appear in the IPCC report. This was because the report was not tasked with defining a level of global warming which might be considered to be catastrophic (or dangerous) but rather was tasked with evaluating the impacts of 1.5°C of warming and comparing them to 2.0°C of warming. The report found that impacts are likely to be measurably worse at 2.0°C of warming compared to 1.5°C of warming. However, the report does not identify any bright-line after which impacts suddenly explode in severity. Most impacts scale with the amount of global warming and the amount of global warming scales with cumulative anthropogenic CO2 emissions. Thus, the severity of impacts can be reduced by reducing anthropogenic CO2 emissions regardless of if/when the 1.5°C or 2.0°C values are passed. The New Yorker article is wrong to assert that there is some bright line at 2.0°C of warming after which we are condemned to catastrophe and human decisions no longer matter. 1- Brown et al(2016) Unforced surface air temperature variability and its contrasting relationship with the anomalous TOA energy flux at local and global spatial scales, Journal of Climate 2- Steffen et al (2018) Trajectories of the Earth System in the Anthropocene, PNAS 3- Nordhaus (1977) Strategies for the control of carbon dioxide, The Efficient Use of Energy Resources 4- Oppenheimer and Petsonk (2005) Article 2 of the UNFCCC: Historical origins, recent interpretations, Climatic Change 5- Shaw (2016) The two degree dangerous limit for climate change 6- UNFCCC (1992) United Nations Framework Convention on Climate Change Report 7- UNFCCC (2009) UNFCCC Conference of Parties: Copenhagen Accord 8- UNFCCC (2015) UNFCCC Adoption of the Paris Agreement. I: Proposal by the President 9-Guldberg et al (2018) Chapter 3: Impacts of 1.5ºC global warming on natural and human systems, In IPCC Special Report on 1.5ºC global warming 10- IPCC (2018) Special Report on 1.5ºC global warming 11- Asayama et al (2019) Why setting a climate deadline is dangerous, Nature Climate Change. Alexis Berg Research Associate, Harvard University: This is inaccurate. I think there is some confusion here. Historically, 2°C has been chosen as some kind of internationally agreed-upon “speed limit” to warming, resulting from a mix of some legacy from earlier scientific discussions about global warming, considerations on the range of past climate variations and analyses of the possible impacts of climate change. For instance see here. So this target doesn’t mean that 1.9°C is safe and 2.1°C or 2.5°C is guaranteed catastrophe. In particular, it doesn’t imply runaway climate change beyond 2°C. Now, last year, a paper came out in PNAS, Trajectories of the Earth System in the Anthropocene1, which did suggest that as early as by 2°C warming, some feedbacks could start kicking in in the climate system that could automatically push the Earth towards a “Hothouse climate”, i.e., 4 or 5°C warming (indeed, a global catastrophe)—feedbacks like methane emissions from melting permafrost, carbon emissions from ecosystem collapse, etc. In other words, the authors suggested that unless we stabilize the climate now at 2°C, then beyond that threshold it would run away uncontrollably towards a hothouse climate, and that the intermediate space between 2 and 5°C, in a way, did not actually exist. It is worth pointing out that, while that possibility can’t be excluded, it does not represent, at least to my knowledge, the consensus amongst scientists. This was a speculative paper intended to highlight, I believe, the high side of the risk distribution.The authors offered, at the time, no real new evidence or climate simulation analysis to substantiate their claims. Climate model simulations, for instance, which do include some of these feedbacks, do not suggest runaway climate change beyond 2°C. So, although the author here doesn’t cite that paper explicitly, what I think happened is that he took the possibility raised somewhat speculatively by this article and interpreted it as certainty and reflecting scientific consensus. This is, I believe, clearly an exaggeration. Unfortunately, since the author also factors in the fact that, in his view, limiting warming to 2°C won’t be possible (it is fair to recognize that it is becoming extremely challenging, as years go by and CO2 accumulates), it leads him to the conclusion that doom is unavoidable, as we’ll cross into beyond-2°C territory and thus will be automatically pushed towards Hothouse climate. This mistaken conclusion that doom is certain is the basis for much of the discussion in the rest of the article on climate actions and priorities and personal attitudes (e.g., hope). 1- Steffen et al (2018) Trajectories of the Earth System in the Anthropocene, PNAS Marcos Fontela Postdoctoral researcher, Institute of Marine Research (IIM-CSIC): The whole essay can be dismantled with a single article: Trajectories of the Earth System in the Anthropocene, published in 2018 Steffen et al1. Biogeophysical feedbacks have different tipping points. Some are in the range of the 2ºC limit, while others would occur at higher temperature anomalies. For example, a critical transition in the Atlantic Meridional Ocean Circulation (AMOC) is not expected unless beyond 3ºC. Potential interactions among the tipping elements of the Earth system could generate tipping cascades, but the farther we stay below 2ºC [or a higher level of warming], the less likely will be the occurrence of tipping cascades. 1- Steffen et al (2018) Trajectories of the Earth System in the Anthropocene, PNAS"
https://science.feedback.org/review/there-is-overwhelming-evidence-that-climate-change-is-human-caused-townhall/,Incorrect,"Townhall, Kurt Schlichter, 2019-09-09","Human-produced carbon might be one of the factors [of climate change], but there’s simply no evidence that it is a significant one.",,"Misleading: The effects of these factors (the sun, volcanoes...) have all been quantified, and human-caused greenhouse gas emissions are clearly the dominant cause of current global warming. Inadequate Support: No research or data is provided to support the author’s assertion.","Natural factors have certainly caused climate changes in the past, but that does not mean human factors are not responsible for climate change now. Observations clearly show that incoming solar radiation and the effects of volcanic eruptions have not changed in a way that could explain global warming. Instead, research has shown that human activities are the cause.","The planet gets hotter, it gets colder, sometimes quickly, sometimes over eons, and there are a bunch of reasons why, like the sun and volcanos. Human-produced carbon might be one of the factors, but there’s simply no evidence that it is a significant one.",,"Patrick Brown Assistant Professor, San Jose State University: [This comment comes from a previous review of a similar claim.] Careful analysis that attempts to take into account all major factors and their evolution in time indicates that anthropogenic increases in greenhouse gasses account for more than 100% of the observed warming on the century timescale (requiring cancellation from cooling influences). See the summary graphic from Carbon Brief, below. Source: Carbon Brief Britta Voss Postdoctoral Research fellow, U.S. Geological Survey: [This comment comes from a previous review of a similar claim.] Solar forcing is much smaller than CO2 forcing. As this figure from the latest IPCC report shows, CO2 radiative forcing (1.68 W/m2) dwarfs solar forcing (0.05 W/m2). Along with other greenhouse gases, CO2 dominates the total radiative forcing when all positive and negative factors are taken into account. Figure – Radiative forcing estimates in 2011 relative to 1750. Values are global average radiative forcing, partitioned according to the emitted compounds or processes that result in a combination of drivers. Source IPCC AR5 Timothy Osborn Professor, University of East Anglia, and Director of Research, Climatic Research Unit: [This comment comes from a previous review of a similar claim.] There is strong evidence that solar forcing cannot explain much of the observed warming at all. The “fingerprint” of solar forcing does not match the observed changes at all, neither over time nor space. Solar forcing would warm both the stratosphere and the surface of the Earth, whereas CO2 warms the surface (and the troposphere) but cools the stratosphere. Using radiosondes and (more recently) satellites, we have observed a warming surface and troposphere together with a cooling stratosphere. See Santer et al (2013)* for one of many studies providing this evidence. Figure –Zonal-mean atmospheric temperature trends in satellite observations from January 1979 to December 2012 showing warming of the lower atmosphere (troposphere) and cooling of the upper-atmosphere (stratosphere), from Santer et al (2013)* Santer et al (2013) Human and natural influences on the changing thermal structure of the atmosphere, PNAS Baird Langenbrunner Associate Editor, Nature Climate Change: [This comment is taken from an earlier review of a similar claim.] First, greenhouse gases are well studied, and their properties are nonnegotiable: They absorb and re-emit longwave radiation, whether they’re in a laboratory setting or in the real atmosphere. To back this up with historical evidence, scientists have known since the 1860s that CO2 is a greenhouse gas and since the 1890s that this will affect the heat budget of the Earth through warming. Even then, these claims were based on empirical evidence, and they’re supported by decades of laboratory research. Second, the link between increased greenhouse gas concentrations and warming continues to be supported by research in the last two decades. One study from 2001[1]used satellites to measure the type of energy entering and exiting Earth’s atmosphere and concluded that increases in greenhouse gases were responsible for extra heat measured between 1970 and 1997. The authors state that their results “provide direct experimental evidence for a significant increase in the Earth’s greenhouse effect that is consistent with concerns over radiative forcing of climate.” (Here, the term “radiative forcing” refers to the extra energy trapped in the atmosphere by greenhouse gases, cause warming.) A more recent study[2]arrived at similar conclusions, confirming predictions of the greenhouse effect in Earth’s atmosphere and providing “empirical evidence of how rising CO2 levels … are affecting the surface energy balance.” In other words, rising CO2 was linked directly to warming, even when things like plant uptake of CO2 were considered. 1 – Harries et al (2001) Increases in greenhouse forcing inferred from the outgoing longwave radiation spectra of the Earth in 1970 and 1997, Nature 2 – Feldman et al (2015)Observational determination of surface radiative forcing by CO2 from 2000 to 2010, Nature Mark Richardson Research Associate, Colorado State University/NASA JPL: [This comment is taken from an earlier review of a similar claim.] [These] comments would have been fair in 1896 when Svante Arrhenius calculated that we could cause serious global warming[1]. World temperatures measurements began in the 1800s and show a warming burst since the 1970s. Last year we checked with satellite scans of the ocean[2], confirming the accuracy of the surface measurements. Global warming is measured fact. Working out the culprits has been like Crime Scene Investigation: Physics Edition. Some evidence comes from a facility in Billings, Oklahoma. Parts of air like water vapour and carbon dioxide naturally glow with infrared heat at very specific frequencies. The Billings site has a device that measured an incredibly precise “fingerprint” of the sky’s heating. Investigators reported in 2015[3] that they found fingerprints across the sky with a clear match on the heating trigger. Below the blue line is the file fingerprint for carbon dioxide (CO2) heating, which we release into the air when we do things like burn coal & oil. This file fingerprint comes from basic physics backed by precise lab readings. The red line is the measured fingerprint in the sky over Billings and is a rock solid match. Each spike is extra heat coming down from the extra CO2 molecules that is heating us up. Measurements in Alaska and from satellites[4]confirm this. This is just one slide in the huge folder of empirical evidence showing human activity to be the main cause of recent warming. 1 – Arrhenius (1896)On the Influence of Carbonic Acid in the Air upon the Temperature of the Ground,Philosophical Magazine and Journal of Science 2 – Hausfather et al (2017)Assessing recent warming using instrumentally homogeneous sea surface temperature records, Science Advances 3 – Feldman et al (2015)Observational determination of surface radiative forcing by CO2 from 2000 to 2010, Nature 4 – Harries et al (2001) Increases in greenhouse forcing inferred from the outgoing longwave radiation spectra of the Earth in 1970 and 1997, Nature Shaun Lovejoy Professor, McGill University: [This comment is taken from an earlier review of a similar claim.] Let’s say you are given only three pieces of information: a) The annual average value of the global temperature from 1880 to 1909 b) The atmospheric CO2 concentration for each year c) The effective climate sensitivity With only this, the temperature over the 104 years between 1909 and 2013 could be incredibly well forecast (black line in the figure below), indeed to about an accuracy of ±0.22 °C (purple lines, 90% confidence limits). This tight limit includes the so-called “pause” of the early 2000s. Knowing only the CO2 therefore allows us to predict the temperature more than 100 years into the future. Given that the total change over this time was 1.1 °C, the prediction is correct to within 20%. We know that the CO2 was anthropogenic, therefore its increase was not caused by a change of temperature. We can conclude that CO2 is responsible for much of the change in temperature over the last century. Figure adapted from Lovejoy (2015), Using scaling for macroweather forecasting including the pause, Geophysical Research Letters"
https://science.feedback.org/review/claim-that-the-earth-has-cooled-since-medieval-or-roman-times-is-false-marc-morano/,Inaccurate,"TFP Student Action, Marc Morano, 2019-08-13","Peer-reviewed studies, geologic records, and all the studies have shown that we have actually cooled since the Roman Warming Period, and likely since the Medieval Warming Period.",,"Factually Inaccurate: Published research actually shows that the last century is the warmest of the last 2,000 years, globally. Fails to grasp significance of observation: The existence of warmer or cooler periods in individual records from a region does not, on its own, represent a global climate event.","There have been regional climate events over the past 2,000 years, which can be seen in records of past climate. However, analysis of global temperatures for this time period shows that current warming is unique in its extent and has exceeded earlier temperatures.","Peer-reviewed studies, geologic records, and all the studies have shown that we have actually cooled since the Roman Warming Period, and likely since the Medieval Warming Period.",,"A recent study1 analyzing a global database of paleoclimate records found that no previous warm or cool period in the last 2,000 years—including the Roman Warm Period and the Medieval Warm Period (also called the Medieval Climate Anomaly)—occurred globally and synchronously. But 20th Century temperatures were the warmest of the last 2,000 years for nearly the entire surface of the Earth. These maps show the timing of the warmest temperatures in named warm periods (or coldest temperatures in named cool periods) over the last 2,000 years. Only the 20th Century warming is global in extent (top right).Source: Neukom et al (2019)1 1- Neukom et al (2019) No evidence for globally coherent warm and cold periods over the preindustrial Common Era, Nature Kevin Anchukaitis Associate Professor, The University of Arizona: 1) Our most up-to-date understanding of global mean temperatures is likely the Last Millennium Reanalysis1. Even accounting for uncertainties, global mean annual temperatures are higher now than any time in the last 2,000 years, with the middle of the 20th century either matching or exceeding Common Era temperatures as well. 2) For the Northern Hemisphere (where we have much better proxy data and a better understanding of the uncertainties), we come to similar conclusions—in Wilson et al (2016)2 we find that the two warmest decades of our reconstruction (from 918 to 2004 CE) were 1994–2003 and 1946–1955. Coming in 3rd place is 1161–1170 CE. So, the latest in large-scale temperature reconstructions do NOT support a claim that temperatures either in the Medieval or Roman periods were warmer than today. 3) Even if these periods were warmer than today (and we currently have no evidence that they were), that would have no bearing on whether CO2 is causing current warming. Current warming is unambiguously caused by CO2 emissions. Past warm and cold periods reflect a mix of internal climate system variability and changes in radiative forcing from volcanoes and solar variability. Current warming is the result of rising atmospheric CO2 concentration, whether or not there were past epochs of widespread warming. 1- Tardif et al (2019) Last Millennium Reanalysis with an expanded proxy database and seasonal proxy modeling, Climate of the Past 2- Wilson et al (2016) Last millennium northern hemisphere summer temperatures from tree rings: Part I: The long term context, Quaternary Science Reviews Rob Wilson Professor, University of St Andrews: Since 2015, several tree-ring based studies of large-scale Northern Hemisphere summer temperatures have shown that the last 10 or 20 year periods are significantly warmer than any other time for the last 1,200 years. A recent study in Nature1 has expanded on this work using a global multi-proxy data-set which suggests that the last 50 years have been warmer than any period of the last 2,000 years. The statement above is therefore incorrect and mis-characterises what is detailed in many studies. In fact, basic conclusions have been rather consistent over the past 20 years—i.e., recent warming is unprecedented for the last millennium (likely for last 2,000), the Sun has almost no detectable attributed impact on climate, and volcanoes have the strongest impact on climate prior to the anthropogenic period. Our knowledge of past climate is better where we have data and poor where we rely on teleconnections and/or interpolation. However, the paleoclimate community and users of the data we generate must appreciate that the 1st millennium of the Common Era is substantially much less constrained than the last 1,000 years and more effort and investment is needed to increase the number of climate proxy records for this earlier period (also the Medieval). Ideally, we should not mix proxy records that express different signals as the climate response to both internal and external forcing varies across different seasons (i.e., summer vs. winter). I would also contentiously add that for the late Holocene, we should minimise the use of proxy archives with poor (>10 years) resolution and substantial (+/- 5-10 years) dating uncertainties. 1- Neukom et al (2019) No evidence for globally coherent warm and cold periods over the preindustrial Common Era, Nature [These comments are taken from a previous review of a similar claim.]"
https://science.feedback.org/review/claim-of-no-us-warming-since-2005-is-directly-contradicted-by-the-data-it-is-based-on/,Inaccurate,"Powerlineblog, Real Clear Energy, WND, James Taylor, John Hinderaker, 2019-08-29",the U.S. Climate Reference Network[...] finds there has been no warming for the past 14 years at least,,"Factually Inaccurate: It is simply false to claim that the data show no warming over that time period. There is a warming trend.  Flawed Reasoning: Even if the US experienced a flat temperature change for 14 years, this would not prove that global warming isn't occurring. The US only covers a small portion of the planet, and a 14-year period is too short to reliably indicate long-term trends over short-term variability.","This article highlights a particular dataset of surface temperature stations in the United States that it says differs from standard datasets, but in reality they match quite closely. Most importantly, the data presented in the article do exhibit a warming trend, making the article's claim simply false.","But a new, improved system to assess surface temperatures established in 2005 by the National Oceanic and Atmospheric Administration, NOAA, indicates otherwise. In fact, the U.S. Climate Reference Network -- comprised of 114 pristinely maintained temperature stations spaced relatively uniformly across the lower 48 states -- finds there has been no warming for the past 14 years at least [...] All of the asserted U.S. warming since 1930 is the product of the controversial adjustments made to the raw data.",,"This article at WND is based on a post by James Taylor at RealClearEnergy and an article at Power Line by John Hinderaker. The WND article, however, was the most widely shared of the three on social media. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: USCRN is a state-of-the-art monitoring network that covers the contiguous US, with pristine-sited triple redundant thermometers sending data automatically via satellite uplinks in real time. It’s an incredibly valuable resource for us to ground-truth temperatures and provides a useful check on the effectiveness of our adjustments to the much-messier weather station network—which is subject to biases from station moves, instrument changes, time of observation changes, and changes in surrounding vegetation or urban form. Since its inception, researchers have compared data from USCRN to the broader weather station network that constitutes our US historical temperature record. We have found that USCRN readings are nearly identical to the US-wide record from the weather station network; if anything, USCRN shows slightly more warming than the existing network (ClimDiv is the old network, USCRN is the new network): Source: NOAA Since it achieved nationwide coverage at the start of 2005, the warming rate (trend) in USCRN annual temperatures is 0.86°F per decade, with uncertainties ranging from -0.58°F to 2.31°F per decade. By contrast, the historical NOAA ClimDiv dataset only shows 0.64°F (ranging from -0.80°F to 2.07°F) per decade. As this is a relatively short time period and only covers around 2% of the surface of the Earth, we shouldn’t read too much into these numbers as an indication of longer-term changes, but we can say that USCRN data is completely consistent with the long-term warming trend, and suggestions that the USCRN “finds there has been no warming for the past 14 years at least” are categorically false. In 2016, I was the lead author on a paper in GRL1 that looked in detail at differences between USCRN and historical weather station networks. We found that not only did USCRN match the weather station network quite well over the full US, but when comparing pairs of nearby USCRN and historical weather stations, the adjustments made by NOAA to historical weather stations bring them into much closer agreement with USCRN stations. This is true even when USCRN stations are not used as part of the adjustment process: Comparing raw and adjusted NOAA data to the USCRN dataset. Source: Hausfather et al (2016)1 1- Hausfather et al (2016) Evaluating the impact of U.S. Historical Climatology Network homogenization using the U.S. Climate Reference Network, Geophysical Research Letters Mark Richardson Research Associate, Colorado State University/NASA JPL: Raw data show more global warming since 1880 than is reported by NOAA [or shown in other datasets]. This is because NOAA “adjusts” temperature data to fairly compare different measurement times, places, and technologies. The cooling effect of adjustments on global temperatures has been shown lots of times, such as with the graph below for 1880—2013 temperatures. A small group of conspiracy theorists flip this reality by “cherry picking”, which means using a fraction of the data to prop up claims that are false globally. It’s the sort of technique that would insist that this is a 100% blue cherry tree. NOAA scientists know that afternoons tend to be warmer than early mornings so it would be dumb to mix, for example, 1940s morning temperature readings with 2010s afternoon readings without accounting for this. They refuse to do obviously, provably dumb things so they carefully correct the data for a fair comparison. In the U.S., thermometers used to be read largely in the afternoon but now tend to be read in the morning1. This means that adjustments in the U.S. are warming, making it a popular choice for hints at conspiracy. There are ways to judge whether new claims are credible. Firstly, do they mention that global adjustments are cooling overall? Secondly, do they discuss reasons for adjustments including measurement time? If the answer is “no” to either then the author is hiding relevant information or is clueless about the topic and you should be very sceptical. Fortunately the scientific method can reliably test new claims through submissions to scientific journals for peer review, which tends to filter out obvious dumb mistakes like ignoring how afternoons are warmer than early mornings. Blog posts, think tanks and newspapers have no such filter. We know that NOAA’s adjustments improve things since they’re tested and updated whenever issues are found. For example, even a blogger who’s hostile to climate science results published a paper confirming that the NOAA U.S. average temperature changes are solid2. Another study by an independent “red team”, partly funded by a Koch foundation, supported NOAA’s conclusions3. I was involved with a check of NOAA’s ocean record using infrared scans from satellites4. The satellites supported NOAA’s results despite baseless & hysterical accusations that had been thrown at the scientists. After more than a decade of being relentlessly wrong, it’s time to be very careful with any new conspiracy claims aimed at the temperature records. [This comment was initially provided as part of a claim review.] 1-Vose et al (2003) An evaluation of the time of observation bias adjustment in the U.S. Historical Climatology Network, Geophysical Research Letters 2-Fall et al (2011) Analysis of the impacts of station exposure on the U.S. Historical Climatology Network temperatures and temperature trends, Journal of Geophysical Research: Atmospheres 3-Rohde et al (2012) A New Estimate of the Average Earth Surface Land Temperature Spanning 1753 to 2011, Geoinformatics & Geostatistics: An Overview 4-Hausfather et al (2017) Assessing recent warming using instrumentally homogeneous sea surface temperature records, Science Advances"
https://science.feedback.org/review/earths-orbit-cannot-explain-modern-climate-change/,Incorrect,"Natural News, Ethan Huff, 2019-08-30","changes in the solar orbit of the earth, along with alterations to the earth’s axial tilt, are both responsible for what climate scientists today have dubbed as “warming”[...]. In no way, shape, or form are humans warming or cooling the planet",,"Flawed Reasoning: Earth's orbital cycles are 20,000 years long—or longer. They cannot explain global warming occurring over a single century.  Factually Inaccurate: Measurements show that incoming solar radiation has not increased over the last century to drive rising temperatures. Instead, greenhouse gas emissions are responsible.","Slowly changing orbital cycles did, indeed, control the timing of ice ages over the last several million years, but they cannot explain the much more rapid climate change seen in the last century. Human-caused greenhouse gas emissions have strengthened Earth's greenhouse effect, and this is clearly the cause of global warming.","[...]changes in the solar orbit of the earth, along with alterations to the earth’s axial tilt, are both responsible for what climate scientists today have dubbed as “warming” (or “cooling,” depending on their agenda). In no way, shape, or form are humans warming or cooling the planet by driving SUVs or eating beef, in other words.",,"This article draws from a NASA webpage explaining the work of Milutin Milankovitch, who developed an explanation for Earth’s ice ages based on calculated cycles in Earth’s orbit. These cycles, Milankovitch reasoned, altered the strength of summer sunlight in the high Arctic, causing great ice sheets to shrink or grow and affecting global climate as a result. The cycles include the shape of Earth’s orbit around the Sun, the angle of tilt of Earth’s axis, and the precession of that axis—like the wobbling of a spinning top. The shortest of these cycles is roughly 20,000 years long, while the shape of the orbit changes over about 100,000 years. The cycles line up with the 40,000 and 100,000-year-long ice ages that occurred over the last 3 million years. The cycles are too long—and change too slowly—to explain the global temperature change measured since the late 1800s. Additionally, the current trend is a gradual decrease of Arctic summer sunlight. Modern warming—which is known to be the result of human-caused greenhouse gas emissions and other human activities—is exceptional in that it has occurred despite that orbital trend1. 1- Kaufman et al (2009) Recent Warming Reverses Long-Term Arctic Cooling, Science Geert Jan van Oldenborgh Senior researcher, KNMI (The Royal Netherlands Meteorological Institute): [This comment comes from a previous review of a similar claim.] Over geological time scales, indeed. However, the rise in temperature of 1 degree Celsius over the last two hundred years is not on a geological time scale, and is not caused by natural phenomena out of our control as suggested here. Both from the negative (there are no natural forcings on the climate that would have produced such heating over the last century) and from the positive (the heating is pretty much what we expect from greenhouse gases minus aerosols) the evidence is very strong that humans are responsible for most of the trend over the last 100 years. Patrick Brown Assistant Professor, San Jose State University: [This comment comes from a previous review of a similar claim.] Careful analysis that attempts to take into account all major factors and their evolution in time indicates that anthropogenic increases in greenhouse gasses account for more than 100% of the observed warming on the century timescale (requiring cancellation from cooling influences). See the summary graphic from Carbon Brief, below. Source: Carbon Brief Britta Voss Postdoctoral Research fellow, U.S. Geological Survey: [This comment comes from a previous review of a similar claim.] Solar forcing is much smaller than CO2 forcing. As this figure from the latest IPCC report shows, CO2 radiative forcing (1.68 W/m2) dwarfs solar forcing (0.05 W/m2). Along with other greenhouse gases, CO2 dominates the total radiative forcing when all positive and negative factors are taken into account. Figure – Radiative forcing estimates in 2011 relative to 1750. Values are global average radiative forcing, partitioned according to the emitted compounds or processes that result in a combination of drivers. Source IPCC AR5 Timothy Osborn Professor, University of East Anglia, and Director of Research, Climatic Research Unit: [This comment comes from a previous review of a similar claim.] There is strong evidence that solar forcing cannot explain much of the observed warming at all. The “fingerprint” of solar forcing does not match the observed changes at all, neither over time nor space. Solar forcing would warm both the stratosphere and the surface of the Earth, whereas CO2 warms the surface (and the troposphere) but cools the stratosphere. Using radiosondes and (more recently) satellites, we have observed a warming surface and troposphere together with a cooling stratosphere. See Santer et al (2013)* for one of many studies providing this evidence. Figure –Zonal-mean atmospheric temperature trends in satellite observations from January 1979 to December 2012 showing warming of the lower atmosphere (troposphere) and cooling of the upper-atmosphere (stratosphere), from Santer et al (2013)* Santer et al (2013) Human and natural influences on the changing thermal structure of the atmosphere, PNAS"
https://science.feedback.org/review/washington-examiner-op-ed-cherry-picks-data-to-mislead-readers-about-climate-models-patrick-michaels-caleb-stewart-rossiter/,-1.6,"The Washington Examiner, Zero Hedge, by Caleb Stewart Rossiter, Patrick Michaels, on 2019-08-25.",,"""The great failure of the climate models""",,,,,"This op-ed article published by The Washington Examiner (and republished by Zero Hedge) claims to provide evidence that climate models are not valid scientific tools able to inform decisions about climate change by focusing on a comparison with specific datasets from the upper atmosphere in the tropics. Scientists who reviewed the article found that it is highly misleading, including a number of false factual assertions, cherry-picking datasets that support their point, failing to account for uncertainties in those datasets, and failing to assess the performance of climate models in an objective and rigorous manner.See all the scientists’ annotations in context. You can also install the Hypothesis browser extension to read the scientists’ annotations in context.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: This article focuses only on specific lines of evidence that climate models disagree with observations. In doing so, the authors ignore research that helps to reconcile differences between models and observations. The authors do not consider alternate datasets and time periods in which models and observations agree. Models are one tool for understanding climate change; their overall credibility does not hinge on one variable, in one domain, over a specific time period, with respect to a set of imperfect observations. Carl Mears Senior Research Scientist, Remote Sensing Systems (RSS): The article contains numerous inaccurate statements, and “cherry-picks” evidence to support its assertion about model accuracy. The article exaggerates the disagreement between the modeled and observed trends in the tropical lower troposphere. Depending on which satellite data set is used, the model-mean trend (1979-2017) in the tropical (30S to 30N) lower tropospheric temperature is 1.73 (RSS dataset) or 2.38 (UAH dataset) times larger than the trends observed by satellites, not 7 times as stated in the article. The article asserts that the satellite and radiosonde temperature records are more accurate than the surface temperature record. I consider this to be unlikely (even though I developed one of the satellite records) as indicated by the smaller spread in trends in the surface record than in the satellite record. The article asserts that the rate of sea level rise has not increased. Recent papers have clearly shown an acceleration in sea level rise, both in satellite altimeter data1 and in a sea level rise reconstruction based on tide gauges2. 1- Nerem et al (2018) Climate-change–driven accelerated sea-level rise detected in the altimeter era, PNAS 2- Dangendorf et al (2019) Persistent acceleration in global sea-level rise since the 1960s, Nature Climate Change Victor Venema Scientist, University of Bonn, Germany: The article makes a large number of claims which have long been known to be wrong. The authors’ ignoring of the counterarguments makes it clear that bypassing the scientific debate and going directly to the public is not helpful for a better understanding of climate change. The main erroneous claim is that numerical climate models are wrong. Even if we would grant them that—or even if we did not have any models—it would still be clear that CO2 would warm the Earth, but we would know less-well how much it warms the Earth, and especially we would know much less about how this changes the rest of the climate system. (How this changes average and severe precipitation and in which regions, how this changes heat waves, the circulation, hurricanes, permafrost, etc.) The risks of climate change would thus be larger without climate models. Mark Richardson Research Associate, Colorado State University/NASA JPL: Measured global temperatures agree pretty well with climate model outputs since 18601 so why does this Washington Examiner article say the opposite? The article’s major argument relies heavily on satellite-based datasets of atmospheric temperatures since the 1970s. These particular satellites were not designed for climate monitoring and unlike with other records, we currently lack enough independent checks of their reliability for climate trends. In the lower atmosphere, for example, processing by Remote Sensing Systems gives about 60% more warming than processing by the University of Alabama Huntsville, even though they use the same raw data. As the developer of a satellite dataset, the Examiner article’s claim that this is the “most reliable” data is not remotely believable to me. The more-uncertain satellite series were preferred over the surface temperature data, based on the baseless accusation that the surface records are “badly compromised” by adjustments to the data, such as those to correct for changes in measurement times, locations and technology. On net, these adjustments shrank reported warming since the 1800s, but the Examiner article incorrectly claims the opposite: “…each serial adjustment has tended to [increase] the warming trend”. The observed global temperature data from different research groups (red, orange, green) keeps agreeing with the climate model range (blue). One adjustment is done because nowadays there are more buoy temperature readings of the ocean, and scientists carefully combined this newer buoy data with older ship-based readings. The Examiner article says that the corrections involved “replacing satellite data with drifting buoys” (untrue) and that such a correction was “guaranteed to put some artificial warming in the data” (untrue, that’s not how the maths works). Independent infrared satellite readings confirm that the new corrections are good, though.2 The Examiner article also talks about two warming periods: a “half-degree from…the first half of the 20th century” and “another half-degree in the last quarter of the century”. This misleads readers since the recent, ongoing warming is about 2-3 times larger than the earlier warming. The warming since 1970 is 0.8-0.9 °C versus the 0.3-0.4 °C in the first half of the 20th century. The Washington Examiner chooses to say that both periods are about the same, at half a degree C (1 °C = 1.8 °F). Later the Examiner cites a UN report by independent scientists to say the “latter half-degree is at least half manmade”, but that’s a bit like saying that the “latter half of the Superbowl is at least half manmade”. While technically true, it could prevent readers from realising that the best estimate is that effectively all of the recent warming is human-caused. The Examiner article misleads in other areas too, such as its claims that measured Arctic warming “runs afoul of basic physics” and “adds non-existent warming” (untrue, about 4 Texas’ area of sea ice extent has melted since the 1970s and buoys and satellites also measure its rapid heating3,4,5). In summary, this article’s conclusions rely heavily on a number of untrue statements, it relies on less-certain datasets and misses vital context. 1- Richardson et al (2016) Reconciled climate response estimates from climate models and the energy budget of Earth, Nature Climate Change 2- Hausfather et al (2017) Assessing recent warming using instrumentally homogeneous sea surface temperature records, Science Advances 3- Boisvert and Stroeve (2015) The Arctic is becoming warmer and wetter as revealed by the Atmospheric Infrared Sounder, Geophysical Research Letters 4- Susskind et al (2019) Recent global warming as confirmed by AIRS, Environmental Research Letters 5- Dodd et al (2014) An Investigation into the Impact of using Various Techniques to Estimate Arctic Surface Air Temperature Anomalies, Journal of Climate Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Annotations: The statements quoted below are from the article; comments are from the reviewers (and are lightly edited for clarity). Computer models of the climate are at the heart of calls to ban the cheap, reliable energy that powers our thriving economy and promotes healthier, longer lives. Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: Assessments of climate change include many lines of evidence. In addition to computer models, observations of many aspects of the climate (e.g. changes in land and sea ice, sea level rise, temperature, humidity, etc.) and paleoclimate evidence is considered. Andrew Dessler Professor, Texas A&M University: No. Climate models are one source of information, but the basis of concern about climate change comes from our understanding of the fundamental physics of the atmosphere. Victor Venema Scientist, University of Bonn, Germany: Also, without numerical computer models we have many lines of evidence that climate change is a problem (basic physics, observed changes, climatic changes in the deep past). The uncertainties and thus the risks would be higher. There would thus be a greater urgency to reduce risks without climate models.[data] show only slight warming, mostly at night and in winter Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: This is something that is also simulated in climate models (larger warming in the minimum daily temperature than the maximum daily temperature). The article the authors reference tends to focus on smaller spatial scales where natural variability plays a larger role. On a global scale, the seasonal asymmetry in warming rates appears to be small. Taking global GISTEMP trends over 1950 – 2018 the range of trends for all seasons is 0.13 – 0.15 degrees C per decade. Lewis and Karoly (2013) Evaluation of Historical Diurnal Temperature Range Trends in CMIP5 Models, Journal of Climate Victor Venema Scientist, University of Bonn, Germany: I would personally not call a warming of the global average temperature of 1°C “slight”, that is considerable warming with clear consequences.there has been no systematic increase in the frequency of extreme weather events, Mark Richardson Research Associate, Colorado State University/NASA JPL: It’s not clear how you judge “systematic increase in the frequency of extreme weather”. Since the 2013 UN IPCC report, we have new data and analysis showing increases in extreme heat and precipitation in many areas due to human-caused global warming. It is misleading not to mention this. Andrew Dessler Professor, Texas A&M University: This is not true. We have good evidence that heat waves are occurring more frequently and that rainfall is falling in more intense events1. These are both things were predicted long ago to occur with global warming. 1- State of the Climate in 2018, Bulletin of the American Meteorological Society Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: This is not as universally true as suggested in this op-ed. Changes in extreme events are difficult to detect and depend on definition and region, but there is evidence for some changes in extreme weather events. For example, evidence is provided for decreases in cold nights, increases in warm days, and increases in heavy precipitation over North America1. 1- IPCC (2013) Climate Change 2013: The Physical Science Basis (Ch. 2, p. 162) Carl Mears Senior Research Scientist, Remote Sensing Systems (RSS): Key Finding from the 4th US National Climate Assessment: “Heat waves have become more frequent and intense, especially in the West. Cold waves have become less frequent and intense across the nation. There have been regional trends in floods and droughts. ”the ongoing rise in sea level that began with the end of the ice age continues with no great increase in magnitude. Mark Richardson Research Associate, Colorado State University/NASA JPL: It misleads readers not to mention the research suggesting accelerated global sea level rise1. While the authors may think a 50-100% acceleration of sea level rise is “no great increase”, readers may misunderstand this. 1- Dangendorf et al (2019) Persistent acceleration in global sea-level rise since the 1960s, Nature Climate Change Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: This is at odds with recent work that finds a “persistent acceleration in global mean sea level rise since the 1960s”1 and the IPCC’s attribution of sea level rise2: “It is very likely that there is a substantial contribution from anthropogenic forcings to the global mean sea level rise since the 1970s. It is likely that sea level rise has an anthropogenic contribution from Greenland melt since 1990 and from glacier mass loss since 1960s. Observations since 1971 indicate with high confidence that thermal expansion and glaciers (excluding the glaciers in Antarctica) explain 75% of the observed rise.” 1- Dangendorf et al (2019) Persistent acceleration in global sea-level rise since the 1960s, Nature Climate Change 2- IPCC (2013) Climate Change 2013: The Physical Science Basis (p. 870) Carl Mears Senior Research Scientist, Remote Sensing Systems (RSS): Acceleration is also seen in data from satellite altimeters1. 1- Nerem et al (2018) Climate-change–driven accelerated sea-level rise detected in the altimeter era, PNAS Let’s find out by comparing the actual temperatures since 1979 with what the 32 families of climate models used in the latest U.N. report on climate science predicted they would be. Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: Considering a larger range of time, Marotzke and Forster (2015)1 generally find good consistency between models and observations. 1- Martozke and Forster (2015) Forcing, feedback and internal variability in global temperature trends, Nature Atmospheric scientist John Christy developed a global temperature record of the lower atmosphere using highly accurate satellite soundings. Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: The authors are referring to microwave sounding instruments, which provide a measure of tropospheric temperature changes. These records are useful, but have substantial uncertainty. In the State of the Climate Report1, various estimates of tropical tropospheric warming had a range of 0.12 – 0.22 K / decade across four datasets (that all use the same underlying satellite data). This is nearly a factor of two difference in the long-term rate of warming. This “structural uncertainty” results because researchers use different approaches to remove known biases that affect long-term trends. No method is perfect, which leads to widely varying estimates of atmospheric warming. 1- Christy et al (2019): Tropospheric Temperature [in “State of the Climate in 2018”], Bulletin American Meteorological Society Victor Venema Scientist, University of Bonn, Germany: This is one of the least reliable warming estimates available. These satellites were not developed to measure temperature, but humidity. The data processing by Christy amplifies measurement uncertainties and several serious errors in the data processing have been found by colleagues. The most serious problem found up to now was not taking into account the orbital decay of the satellites.since 1979 to the most reliable observations — those made by satellites and weather balloons over the vast tropics.Mark Richardson Research Associate, Colorado State University/NASA JPL: These are not the “most reliable” observations. They have the largest issues with lack of independent data to check against, and different groups come up with temperature trends that are far more different than the surface temperature records. Andrew Dessler Professor, Texas A&M University: These are hardly the most reliable measurements. For a description of the tortured history of the satellite measurements, see page 8 of this document. In fact, the surface temperature record is much more reliable and the models agree well with it. It’s as likely that unresolved errors in the satellite record are responsible for the errors as problems in the models. Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: Beware of cherry-picking: It is not established that satellites are the “most reliable” observations, that the tropics are the best domain with which to compare observations or models, or that we should only consider post-1979 satellite era data. Victor Venema Scientist, University of Bonn, Germany: This plot hides the large differences between these highly uncertain estimates by only showing the average. the models predicted seven times as much warming as has been observed Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: The op-ed authors reference the 2017 State of the Climate Report. I helped prepare the “Lower and Mid-Tropospheric Temperature” section and it is unclear where the authors’ statistic comes from (“seven times as much warming…”). The average CMIP5 model warming in the tropical troposphere does outpace observations (by a factor of 1.5 – 3.3, depending on dataset). This issue deserves (and has received) scrutiny.1,2,3,4,5,6 The difference in warming rates between observations and models largely arises in the early 2000s. A number of assessments have concluded that this slowdown in warming in the 2000s is in part due to natural variability (the Earth’s warming was slowed due to climate variability) and forcing (the real world experienced different solar and volcanic aerosol forcing than what was used in the models). Models do simulate natural “hiatus” periods like that experienced in the early 2000s, but, since they are random, they generally do not occur at the same times as in the real world (though some models happened to have a slowdown in warming in the early 2000s). Furthermore, forcing agents (greenhouse gases, aerosols, solar changes) are prescribed to models. Since we do not know the exact evolution of forcing agents for future projections, they are estimated. In this case, the estimated forcing was different than what occurred in the real world. When these issues are taken into account, models and observations are in agreement. Over long periods, when natural variability is a smaller issue, models and observations agree on the rate of warming. Assessments of model projections of climate change show that models have typically been quite skillful (e.g. here). 1- IPCC (2013) Climate Change 2013: The Physical Science Basis (Ch. 9, Box 9.2) 2- Meehl et al (2014) Climate model simulations of the observed early-2000s hiatus of global warming, Nature Climate Change 3- Gleisner et al (2015) Recent global warming hiatus dominated by low‐latitude temperature trends in surface and troposphere data, Geophysical Research Letters 4- Medhaug et al (2017) Reconciling controversies about the ‘global warming hiatus’, Nature 5- Santer et al (2017) Comparing Tropospheric Warming in Climate Models and Satellite Data, Journal of Climate 6- Santer et al (2017b) Causes of differences in model and satellite tropospheric warming rates, Nature Geoscience on average, the projected heating by the models is three times what has been observed. Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: As suggested in the last comment this statistic is quite uncertain (1.5 – 3.3). Some climate models simulate less warming than some satellite datasets. The reason that the average of the CMIP5 models exhibits more warming than observations is in part due to natural variability and problems with the forcing (aerosols, solar changes, etc.) in the models. This is a critical error. Getting the tropical climate right is essential to understanding climate worldwide. Andrew Dessler Professor, Texas A&M University: This is only a critical error because they’re desperate to discredit the models. If the disagreement were in the polar regions, they’d be talking about how important it is to get the polar regions right. Obviously, you want to get everything right, but we live on the surface, so getting that right is the most important—and the models do that. Victor Venema Scientist, University of Bonn, Germany: So apparently the previous paragraph is not just about the upper atmosphere at around 10 km height, but also just about the tropics. That is a tiny remote part of the climate. Most of the atmospheric moisture originates in the tropical ocean, and the difference between surface and upper atmospheric temperature determines how much of the moisture rises into the atmosphere.Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: The relative warming between the surface and the troposphere in both models and observations is in accord with our physical understanding of the tropical atmosphere.1 Po-Chedley et al (2015) Removing Diurnal Cycle Contamination in Satellite-Derived Tropospheric Temperatures: Understanding Tropical Tropospheric Trend Discrepancies, Journal of Climate Carl Mears Senior Research Scientist, Remote Sensing Systems (RSS): Satellite-observed increases in atmospheric moisture content agree with satellite datasets that show more warming.1 1- Mears et al (2015) Intercomparison of total precipitable water measurements made by satellite-borne microwave radiometers and ground-based GPS instruments, Journal of Geophysical Research Globally averaged thermometers show two periods of warming since 1900: a half-degree from natural causes in the first half of the 20th century, before there was an increase in industrial carbon dioxide that was enough to produce it, and another half-degree in the last quarter of the century. Mark Richardson Research Associate, Colorado State University/NASA JPL: The earlier warming (~0.3-0.4 °C) is about a third to a half of the warming since the 1970s (0.8-0.9 °C). They are not comparable, and selecting “the last quarter” of the 20th century to ignore the warming since 2000 misleads readers. Secondly, human activity was sufficient to cause warming in the first half of the 20th century. Victor Venema Scientist, University of Bonn, Germany: To be clear, that is half a degree Celsius, a full degree Fahrenheit. The latest U.N. science compendium asserts that the latter half-degree is at least half manmade. Carl Mears Senior Research Scientist, Remote Sensing Systems (RSS): The recent US National Climate Assessment1 finds that it is extremely likely that more than half of the temperature rise since 1951 is human-caused, and the likely human contribution is 93% to 123%. More than 100% means that the human caused warming would be higher, except that other unrelated changes caused cooling that partially offset the warming. 1- Fourth National Climate Assessment (2018) Part 1, Chapter 3 Victor Venema Scientist, University of Bonn, Germany: The best estimate is that all of the warming is man-made. The first adjustment changed how the temperature of the ocean surface is calculated, by replacing satellite data with drifting buoys and temperatures in ships’ water intake. Mark Richardson Research Associate, Colorado State University/NASA JPL: This isn’t what happened. Satellite data was not replaced, it was never there in the first place. Independent satellite data confirmed that the new corrections are solid.1 1- Hausfather et al (2017) Assessing recent warming using instrumentally homogeneous sea surface temperature records, Science Advances But the thermometer records showed that the warming stopped from 2000 to 2014. Until they didn’t. In two of the four global surface series, data were adjusted in two ways that wiped out the “pause” that had been observed[…] Andrew Dessler Professor, Texas A&M University: This section completely misrepresents the efforts to produce a global-average temperature data set. There are 4 scientific groups producing 4 independent records. They all agree and most of them post their code, so you can see exactly how they do the calculation—there’s certainly nothing nefarious going on. There are adjustments to correct for known issues in the data, but they don’t have much of an effect on the global average temperature record. The warming of the surface record is supported by many independent data: loss of ice all over the globe, warming of the ocean, sea level rise, and, yes, there’s reasonable agreement between the satellite and surface temperature records (see Table 2.3 of the 2018 State of the Climate report1). 1- State of the Climate in 2018, Bulletin of the American Meteorological Society Victor Venema Scientist, University of Bonn, Germany: I had not expected anyone daring to use this argument in 2019. Especially nowadays, you do not need statistics to clearly see that global warming has simply continued. See warming estimate below. The buoy temperatures, which are measured by precise electronic thermistors, were adjusted upwards to match the questionable ship data. Given that the buoy network became more extensive during the pause, that’s guaranteed to put some artificial warming in the data. Mark Richardson Research Associate, Colorado State University/NASA JPL: The direction of this adjustment does not affect the trends. This has been repeatedly checked and is well known. While the article says “that’s guaranteed to put some artificial warming in the data”, it’s actually guaranteed not to do that. Because mathematics. This runs afoul of basic physics. Mark Richardson Research Associate, Colorado State University/NASA JPL: Sure, over ice the surface is limited in how much it can warm. Satellite data and buoys confirm that the Arctic is warming and that the data records needed updating1,2,3. 1- Boisvert and Stroeve (2015) The Arctic is becoming warmer and wetter as revealed by the Atmospheric Infrared Sounder, Geophysical Research Letters 2- Susskind et al (2019) Recent global warming as confirmed by AIRS, Environmental Research Letters 3- Dodd et al (2014) An Investigation into the Impact of using Various Techniques to Estimate Arctic Surface Air Temperature Anomalies, Journal of Climate The second big adjustment was over the Arctic Ocean Victor Venema Scientist, University of Bonn, Germany: This is not an adjustment. Some temperature datasets did not include parts of the Arctic in their estimates of the global mean temperature. Because the Arctic warmed much in this period, these datasets showed less short-term warming. This was taken into account in their uncertainty estimates, which should have been taken into account by people wrongly claiming global warming had stopped between 2000 and 2014. there’s plenty of ice over much of the Arctic Ocean. Now, for example, when the sea ice is nearing its annual minimum, it still extends part way down Greenland’s east coast. Mark Richardson Research Associate, Colorado State University/NASA JPL: There’s still about 5 million sq km of ocean where >15 % is ice covered, but that’s down by ~3 million sq km (4 Texases, if you will). Even if there’s still ice near Greenland. But each serial adjustment has tended to make the early years colder, which increases the warming trend. Mark Richardson Research Associate, Colorado State University/NASA JPL: While this says that adjustments increase the total warming, they actually decrease it since the 1800s. Andrew Dessler Professor, Texas A&M University: This is absolutely wrong. The adjustments to the global average warming REDUCE the trend, not increase it. Shelters in poorer countries are not repainted as often, and darker stations absorb more of the sun’s energy. Victor Venema Scientist, University of Bonn, Germany: This argument would only make sense if the authors assume that these shelters are a century old and never were painted in that time. It’s no surprise that poor tropical countries show the largest warming from this effect. Victor Venema Scientist, University of Bonn, Germany: This wrong claim may be the clearest example of why it is a problem that Michaels and Rossiter bypass science and go directly to the public with this article. The statistical analysis in the article they link to is wrong and this has been known since at least 2009. All this is to say that the weather balloon and satellite temperatures used in Christy’s testimony are the best data we have, and they show that the U.N.’s climate models just aren’t ready for prime time. Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: The consistency of the surface records and the well-documented, large uncertainty in weather balloon and satellite datasets suggests that this is not true. Carl Mears Senior Research Scientist, Remote Sensing Systems (RSS): Also, there are large areas of the tropical oceans with almost no weather balloon observations, including the eastern Tropical Pacific. Andrew Dessler Professor, Texas A&M University: The climate models do a good job in the most important parameter: surface temperature. They’ve also made many many other successful predictions which have been borne out by observations, such as changes in extreme precipitation. Overall, the models have been a lot more successful than unsuccessful. Whether they’re good enough for guiding policy is not a scientific judgment but a political one. Given the models’ success at reproducing the surface record and the sketchy history of the satellite data, one could reasonably conclude that the models can and should be used to guide policy. If, on the other hand, you want to wait until the models are perfect, which the authors of this article apparently want to do, then you’ll never take action to address climate change."
https://science.feedback.org/review/prediction-extinction-rebellion-climate-change-will-kill-6-billion-people-unsupported-roger-hallam-bbc/,Incorrect,"BBC News, Roger Hallam, 2019-08-17","I am talking about the slaughter, death, and starvation of 6 billion people this century—that's what the science predicts.",,"Inadequate Support: While Hallam claims to be presenting a prediction from the scientific literature, this claim is not supported by published research.","Research shows that continuing climate change results in a broad array of serious threats to humans and other species. However, counter to Hallam's statement, published studies have not predicted 6 billion human deaths this century and there is no credible mechanism referred to justify how this could happen.","I am talking about the slaughter, death, and starvation of 6 billion people this century—that's what the science predicts.",,"Amber Kerr Researcher, Agricultural Sustainability Institute, University of California, Davis: Mr. Hallam’s claim that “the science predicts” that six billion people are headed for slaughter and starvation by 2100 is simply not correct. No mainstream prediction indicates anywhere near this level of climate-change-induced human mortality, for any reason. The effects of war, disease, and weather disasters are somewhat harder to anticipate (and outside of my core expertise), so I will focus the remainder of my reply on food supply issues. It is likely that climate change will exacerbate food insecurity in many parts of the world, especially in the developing tropics, but even under the worst-case scenarios (e.g.10-20% yield declines of staple crops, combined with gross income inequality, political instability, and continued high population growth rates), it is hard to conceive how the death toll would exceed tens of millions or, at most, the low hundreds of millions. Of course, a potential death toll of tens of millions is gravely alarming and should be treated with great moral urgency. But I do not believe it is helpful to grossly exaggerate the predictions that have been made. It should also be noted that: (1) Many temperate regions will likely see increased crop yields under future climate, due to warmer temperatures and the CO2 fertilization effect. Depending on the extent of global trade and cooperation, these yield increases could help to partially ameliorate decreases experienced elsewhere. Many agricultural impact projections don’t include the CO2 fertilization effect, due to uncertainty, but in reality this effect will probably help soften the blow of climate change to some extent. (For example, global wheat production may be more likely to increase than decrease; Liu et al. 2018 Global Change Biology1.) (2) Food production and distribution is greatly dependent on policy; it is not an inexorable biophysical process. It is within our current capabilities to produce and distribute enough food for the 10 billion people who will likely be alive in 2100, if we reduce wastage, eat more plant-based foods, increase the efficiency of production, and ensure more equitable distribution. Climate disruptions will make this more challenging, but by no means impossible. In support of point (2), Ch. 7 of the 2014 IPCC 5th Assessment Report, WGII (Impacts)2, states that: “It is only about as likely as not that the net effect of climate and CO2 changes on global yields will be negative by 2050, but likely that such changes will occur later in the 21st century. At the same time, it is likely that socioeconomic and technological trends, including changes in institutions and policies, will remain a relatively stronger driver of food security over the next few decades than climate change.” 1- Liu et al (2018) Global wheat production with 1.5 and 2.0°C above pre‐industrial warming, Global Change Biology 2- IPCC (2014)Climate Change 2014: Impacts, Adaptation, and Vulnerability Patrick Brown Assistant Professor, San Jose State University: Hallam’s claim is of low scientific credibility. It is wild speculation, based much more on his imagination than “the science”. Presumably, many of the 6 billion deaths that Hallam mentions are imagined to come about due to starvation, induced from climate-change-caused crop failures. Food security under climate change is a concern. However, most of the concerning projections that get attention are defined as reductions in yield (e.g. calories grown per unit area) relative to a no climate change scenario (not relative to the yield today). This is very different than a projection of a reduction in the total production of calories relative to today. In order to project total production into the future, technological and economic factors would also need to be taken into consideration. For example, over the historical period of global warming, technological advancements have increased yields by 100-200% in spite of any negative impact of climate change. Even if this yield trend were to reverse, the total production of calories might not be affected if economic forces cause more land to be used for agriculture. In other words, if yields were to be reduced by 10% that does not translate directly into 10% less food available. It is likely that the reduction in yield would stimulate increased land use for agriculture. In this example, if 10% more land were used for agriculture, total production would remain unaffected. All these factors would need to be reckoned with before one could make any credible projection of reduced food production in the future, much less a projection as outlandish as “…starvation of 6 billion people”. Peter Kalmus Data Scientist, Jet Propulsion Laboratory: [Update 23 August 2019: This comment was updated for clarity.] What science projects under plausible scenarios of human courses of action is varying degrees of further disruption of fundamental planetary life support systems (e.g. water, agriculture, ecosystems) needed to support the nearly 8 billion humans currently living on Earth. This disruption poses some degree of existential risk to civilization as we know it—with the amount of risk likely still depending on how rapidly we reduce radiative and ecological forcings—but these degrees of risk are not quantified with any certainty. Ice models have had difficulty projecting the melting rate of the Greenland ice sheet; predicting the mechanism of the collapse of civilization and the number of lives lost as a result is a far more complex problem, and there is no scientific consensus that six billion lives will be lost. On the other hand, models have tended to underestimate ice sheet melting, and model projections in general have been systematically “conservative.” I unfortunately don’t see how the possibility of six billion deaths can be ruled out with confidence, especially when the intrinsically unpredictable but real possibility of climate-related war (which could include nuclear weapons) is considered. In other words, Hallam’s claim is speculative, but given the depth and rapidity of anthropogenic change, so is confidently ruling it out. While I don’t agree that “science predicts” the death of six billion people, in my opinion Hallam’s broader warning has qualitative merit and in the context of a lay translation of risk his use of “six billion” might reasonably be interpreted as figurative, an illustration of a worst-case scenario (again, that I don’t think can be ruled out). Whether to interpret this claim literally or figuratively is a question perhaps best left to humanists. Given this ambiguity I judge it “unrateable.” Ken Caldeira Senior Scientist, Carnegie Institution for Science: This statement is incorrect. I know of no climate model simulation or analysis in the quality peer-reviewed literature that provides any indication that there is a substantially non-zero probability of “starvation of 6 billion people this century” as a result of climate change. Climate damage has been discussed extensively in various IPCC reports and in the peer-reviewed academic literature. Estimates of climate change damage for this century, in business-as-usual scenarios, are typically in the range of a few percent of global GDP to tens-of-percent of GDP for the most extreme damage functions in the most extreme scenarios. There is no analysis of likely climate damage that has been published in the quality peer-reviewed literature that would indicate that there is any substantial likelihood that climate change could cause the starvation of 6 billion people by the end of this century."
https://science.feedback.org/review/rick-perrys-claim-that-us-is-leading-the-world-in-emission-cuts-is-misleading-fox-news/,Misleading,"Fox News, Rick Perry, 2019-08-13","I think about all the 194 [countries] that signed onto the Paris accord, the U.S. is the one that's leading the world in reducing emissions",,"Misleading: It's true that US emissions have declined in recent years, in part because of newer natural gas power plants replacing inefficient coal plants, which emit more CO2. However, the claim that the US would be “the one” country leading in reducing emissions fails to acknowledge that many other countries are reducing emissions faster than the US, starting from a per capita emission level that is already well below the United States' and have policies in place to further cut emissions. ","While Perry's statement isn't perfectly clear in its meaning, it suggests that the United States is reducing emissions the fastest—and that few other countries are reducing emissions at all. That is not true. Emissions in many EU nations are falling by a greater percentage than in the US (and they also emit much less per capita). However, since the United States emits the second most among nations, a given percentage decrease by the US represents more tons of CO2 than a similar decrease by another individual nation.","The reality is that the United States is lowering emissions—one of the only countries in the world. I think about all the 194 [countries] that signed onto the Paris accord, the U.S. is the one that's leading the world in reducing emissions... America [is] transitioning away from old inefficient power plants to natural gas plants.",,"When asked for clarification, a spokesperson for the US Department of Energy told Climate Feedback, “The US leads the world in actual [greenhouse gas] emissions reductions by orders of magnitude compared to any other country since 2005.” Since the United States is the second-largest emitter of greenhouse gases, a 1% decrease (for example) would represent a greater cut than many nations emit, in total. However, this would not typically be described as a stronger reduction than a smaller nation making a 5% cut. Additionally, “orders of magnitude” implies that absolute US emissions have fallen by 100x or more than any other nation. (One order of magnitude means a factor of ten.) Between 2005 and 2017, US CO2 emissions fell by about 862 million tons (14%), while the United Kingdom’s fell by about 185 million tons (22%)—a difference of less than 5x.US emissions also increased by about 140 million tons in 2018, though 2019 emissions are expected to be lower. Jan Ivar Korsbakken Senior Researcher, CICERO Center for International Climate Research: Yes, the US is transitioning away from “old inefficient power” (which presumably means coal power plants, most of which are quite old and inefficient in the US) to natural gas plants, and that is the single most important reason why US CO2 emissions have seen a downward trend since the mid-2000s. The rest of his statement is vague and imprecise enough that you can probably construct some interpretation that turns out to be correct, but I would rate it as “mostly incorrect”. The United States is one of the countries in the world that have been lowering emissions, but the wording suggests that there are very few countries doing so, which is not true. US emissions have had a clear downwards trend since the late 2000s, and although a big part of that can be attributed to the financial crisis, the trend has continued even after the economy started to recover. But the EU as a whole has followed a similar trend, and many individual European countries have seen much greater declines in emissions. Outside of Europe and the US there aren’t a lot of countries whose emissions are going down. Maybe that could justify saying that the US is “one of the only countries in the world”, but to me it sounds like he’s trying to give the impression that the US is more unique than that. Source: Global Carbon Project As for the US being “the one that’s leading the world in reducing emissions”, that is a very dubious claim. Emissions are going down mainly because of economic factors (natural gas out-competing coal-fired power plants, as well as energy efficiency improvements) and in part because of regulation put in place by previous administrations (in particular pollution limits for coal-fired power plants and to some extent earlier support for renewable energy, and further assisted by vehicle mileage standards and other energy efficiency measures). It’s happening more in spite of the policies of the current administrations than because of them. Also, there are many countries in Europe that have reduced emissions more, and the EU is currently pursuing much more active policies to reduce emissions further, while climate policies in the US have largely stagnated or are even being rolled back. All in all, it doesn’t add up to a very convincing leadership role for the US. You can, of course, make the case that the US had a decisive leadership role in bringing the Paris agreement into existence in the first place, under the previous administration, but I assume that’s not what Perry is trying to brag about. Joeri Rogelj Professor, Centre for Environmental Policy at Imperial College London: To stop global warming, global CO2 emissions have to be brought down to net zero. Around 2005, the US was generating and dumping about 6 billion metric tons of CO2 into the atmosphere to satisfy its energy demand. Currently, the US is currently still putting about 5 billion metric tons of CO2 into the atmosphere. That is less than in 2005, but still about one-seventh of total global energy-related CO2 emissions and far from what would be required to limit warming to below 2 degrees Celsius. Without a clear long-term strategy to eliminate all net emissions of CO2, the US is clearly not leading on climate change. Simply transitioning to natural gas plants with lower carbon intensity lowers CO2 emissions in the near-term (but locking in CO2 emissions in the longer term) because the built-up infrastructure will be operated for several decades and continue to produce and emit CO2.1 Over the same period, other countries have also shown much stronger emissions reductions (see figure below from Le Quéré et al, 20192). Fossil fuel CO2 emissions for 18 countries, including the US. Change compared to 2000-2005 average. Developing countries have overall much lower emissions, particularly per person, and while the responsibility for bringing global CO2 emissions to zero is a shared one, currently the US is still far from being a global leader in this field. 1- Tong et al (2019) Committed emissions from existing energy infrastructure jeopardize 1.5 °C climate target, Nature 2- Le Quéré et al (2019) Drivers of declining CO2 emissions in 18 developed economies, Nature Climate Change"
https://science.feedback.org/review/its-not-true-that-co2-only-increases-after-temperature-rises-william-happer-ice-age-now/,Flawed reasoning,"Ice Age Now, Robert W. Felix, William Happer, 2017-02-19","CO2 does not cause climate change, it RESPONDS to it [...] temperature always changes first, and CO2 follows",,"Flawed Reasoning: A lag between the initiation of past warming due to other factors and rising CO2 does not mean mean that CO2 cannot have caused temperature to increase further. Misrepresents a complex reality: CO2 has been shown to begin increasing before temperature in some instances of past climate change, but also acted as a feedback that amplified warming caused by other factors like cycles in Earth’s orbit.","Because of the physics of the transfer of electromagnetic radiation, CO2 acts as a greenhouse gas, meaning that temperatures must increase as the concentration of CO2 increases. This is true whether natural factors initiate warming (as in many past climate changes) and the release of CO2, or the warming is initiated by a release of CO2 (as humans have done).","CO2 does not cause climate change, it RESPONDS to it [...] temperature always changes first, and CO2 follows",,"Christopher Colose Research Scientist, SciSpace LLC, NASA Goddard Institute for Space Studies: This is both false and irrelevant. Claims that “CO2 led temperature in the past, therefore cannot have caused it to rise” originated over a decade ago from a misrepresentation of ice core research (that itself has been subject to significant refinements in dating). It was based on the fallacy that since other factors influence climate (in this case, changes in the Earth-Sun geometry) and that the carbon cycle is affected by climate, the converse cannot be true. Of course, this is not logically coherent, and in practice is wrong since the radiative effect of CO2 is well-established. Indeed, CO2 would not be expected to fluctuate on its own 100,000 year timescale on its own, independent of the climate. In fact, more recent research1 shows that CO2 still led global temperatures and the full deglacial process, unlike in older literature that examined only Antarctic sites. CO2 has also “led” global temperature on geologic timescales, and is largely responsible for how Earth’s temperature evolved over the last 50 million years. There are many ways to change the partitioning of carbon between the Earth and atmosphere, and how this happens is not relevant for the fact that if more CO2 is in the atmosphere, the planet will get warmer. Today, however, the excess source of carbon to the atmosphere is from humans. 1- Shakun et al (2012) Global warming preceded by increasing carbon dioxide concentrations during the last deglaciation, Nature Lauren Simkins Assistant Professor, University of Virginia: This claim is flawed. Ice core records of past greenhouse gas and atmospheric temperature change1, coupled with records of ocean temperature and circulation changes2, indicate that there are complex feedbacks between earth-atmosphere-ocean changes that lead to naturally variable greenhouse gas changes. In some cases during past deglaciations, increases in CO2 have lagged methane (CH4) increases and associated atmospheric temperature rise, owing to natural processes that induce greenhouse gas release into the atmosphere. This is not the case for twentieth century and beyond human-induced atmospheric CO2 and temperature increases. Regardless of the source and cause of atmospheric CO2 increase, it will have a warming effect. Basic science does not change; CO2 is a greenhouse gas that is released into the atmosphere by burning of fossil fuels and leads to atmospheric warming. 1- Monnin et al (2001) Atmospheric CO2 Concentrations over the Last Glacial Termination, Nature 2- Skinner et al (2010) Ventilation of the Deep Southern Ocean and Deglacial CO2 Rise, Science Jeremy Fyke Postdoctoral researcher, Los Alamos National Laboratory: In the natural Earth system, CO2 release acted as a feedback of naturally-forced change (e.g. due to millennial-scale, gradual, changes in the Earth’s orbit). Thus, CO2 is clearly established as an important forcer of, for example, ice ages. This demonstrates it’s effectiveness as a radiative gas. Now, of course, the situation is flipped because humans are actively emitting CO2. This is why it is now a “forcer” rather than a “feedback”. This change in no way impacts our century-old understanding of how CO2 warms the climate.[These comments are taken from a previous evaluation of a similar statement.]"
https://science.feedback.org/review/claim-that-cosmic-rays-are-a-crucial-player-for-current-climate-change-is-unsupported-nir-shaviv-electroverse-global-warming-policy-foundation/,Incorrect,"Electroverse, Cap Allon, Nir Shaviv, 2019-08-11","Based on the increase of solar activity during the twentieth century, it should account for between half to two-thirds of all climate change",,"Misleading: Evidence shows that solar activity can explain very little of the observed warming since the Industrial Revolution. Inadequate support: The claim that cosmic rays are a ""crucial player"" for the climate is not representative of published research on the topic.",It is clear from many lines of evidence that human activities—not solar activity—are responsible for modern climate change.,"'Based on the increase of solar activity during the twentieth century, it should account for between half to two-thirds of all climate change'[...] Both Galactic and Solar Cosmic rays hitting Earth’s atmosphere create aerosols which, in turn, seed clouds (Svensmark et al) — making them a crucial player in earth’s weather and climate.",,"The article mentions cosmic rays, claiming that changes in cosmic ray nucleation of clouds (via solar activity) can explain most of modern global warming. The effect of cosmic rays has been studied extensively1,2, leading to the conclusion that cosmic rays have not correlated with global cloud cover or temperature. Pierce and Adams conclude that: “changes in cloud condensation nuclei from changes in cosmic rays during a solar cycle are two orders of magnitude too small to account for the observed changes in cloud properties; consequently, we conclude that the hypothesized effect is too small to play a significant role in current climate change”1, While Agee et al conclude: “the observational results presented, showing several years of disconnect between Galactic Cosmic Rays and lower-troposphere global cloudiness, add additional concern to the cosmic ray–cloud connection hypothesis.” An experiment at CERN that directly tested the ability of cosmic rays to nucleate cloud droplets found that “variations in cosmic ray intensity do not appreciably affect climate through nucleation in the present-day atmosphere.”3 The 2013 IPCC report summarized research on this topic when it stated, “Cosmic rays enhance new particle formation in the free troposphere, but the effect on the concentration of cloud condensation nuclei is too weak to have any detectable climatic influence during a solar cycle or over the last century.”4 The scientists’ comments below explain that besides this cosmic ray hypothesis, the solar radiative forcing fluctuations are also insufficient to explain climate changes over the past decades—in contrast to the radiative forcing due to the increased greenhouse gases released by human activities, which matches the magnitude of the observed warming. 1- Pierce and Adams (2009) Can cosmic rays affect cloud condensation nuclei by altering new particle formation rates?, Geophysical Research Letters 2- Agee et al (2011) Relationship of Lower-Troposphere Cloud Cover and Cosmic Rays: An Updated Perspective, Journal of Climate 3- Dunne et al (2016) Global atmospheric particle formation from CERN CLOUD measurements, Science 4- IPCC (2013) Chapter 7, Climate Change 2013: The Physical Science Basis Patrick Brown Assistant Professor, San Jose State University: [This comment comes from a previous review of a similar claim.] Careful analysis that attempts to take into account all major factors and their evolution in time indicates that anthropogenic increases in greenhouse gasses account for more than 100% of the observed warming on the century timescale (requiring cancellation from cooling influences). See the summary graphic from Carbon Brief, below. Source: Carbon Brief Britta Voss Postdoctoral Research fellow, U.S. Geological Survey: [This comment comes from a previous review of a similar claim.] Solar forcing is much smaller than CO2 forcing. As this figure from the latest IPCC report shows, CO2 radiative forcing (1.68 W/m2) dwarfs solar forcing (0.05 W/m2). Along with other greenhouse gases, CO2 dominates the total radiative forcing when all positive and negative factors are taken into account. Figure – Radiative forcing estimates in 2011 relative to 1750. Values are global average radiative forcing, partitioned according to the emitted compounds or processes that result in a combination of drivers. Source IPCC AR5 Timothy Osborn Professor, University of East Anglia, and Director of Research, Climatic Research Unit: [This comment comes from a previous review of a similar claim.] There is strong evidence that solar forcing cannot explain much of the observed warming at all. The “fingerprint” of solar forcing does not match the observed changes at all, neither over time nor space. Solar forcing would warm both the stratosphere and the surface of the Earth, whereas CO2 warms the surface (and the troposphere) but cools the stratosphere. Using radiosondes and (more recently) satellites, we have observed a warming surface and troposphere together with a cooling stratosphere. See Santer et al (2013)* for one of many studies providing this evidence. Figure –Zonal-mean atmospheric temperature trends in satellite observations from January 1979 to December 2012 showing warming of the lower atmosphere (troposphere) and cooling of the upper-atmosphere (stratosphere), from Santer et al (2013)* Santer et al (2013) Human and natural influences on the changing thermal structure of the atmosphere, PNAS"
https://science.feedback.org/review/yet-another-express-article-falsely-warns-of-a-solar-induced-ice-age-sean-martin/,Incorrect,"Express, Sean Martin, 2019-07-29","The current solar minimum could last for more than three decades which could lead to temperatures plummeting across the globe, scientists have warned.",,"Inadequate support: The article quotes from a study (misidentified as published in Nature; it was actually published in Scientific Reports) but did not check with outside experts, who would have explained its key flaws. [UPDATE: That study was retracted by the journal on 4 March, 2020, for errors.] Misunderstanding of science: A solar minimum would not cause cold weather across the globe.","Express articles repeat this claim frequently, but research does not support the idea of imminent global cooling due to low solar activity. It is not known that a ""grand solar minimum"" will occur, but even if it did, the temperature effect would be much smaller than human-caused warming.","The current solar minimum could last for more than three decades which could lead to temperatures plummeting across the globe, scientists have warned.",,"This article copies (in part) from previous Express stories making similar claims, such as this one previously reviewed by Climate Feedback. Similar stories from other outlets have been seen to propagate widely across the internet, despite lacking scientific credibility. UPDATE (8 August 2019): A correction has been added to this article, and the above claim has been removed. However, while the correction states that “Northern hemisphere temperatures during [the Maunder Minimum] were reduced by 0.2 degrees C during a period of global cooling”, the article itself still states that “temperatures in the northern hemisphere dropped by 1.3 degrees celsius [sic]”. That number appears to be taken from a 2001 study, where it referred to wintertime temperatures on land (rather than an annual average for the entire Northern Hemisphere). The article still does not explain that a hypothetical grand solar minimum would only be expected to reduce human-caused global warming by about 0.1 °C. UPDATE (19 August 2019): The article has been corrected again, removing the incorrect claim about Northern Hemisphere temperatures during the Maunder Minimum and clarifying the likely climate impact of a hypothetical grand solar minimum in the future. Michael Lockwood Professor of Space Environment Physics, University of Reading: [This comment is taken from an evaluation of a similar statement.] The Maunder minimum [mentioned in the article] was NOT (repeat NOT) a period of decades of freezing weather. It was a period when Europe had a higher fraction of cold winters but summers were, if anything, warmer in the Maunder minimum (as seen, for example, in the central England Temperature measurements) and paleoclimate data show a longer interval of slightly lower global temperatures (often massively misleadingly called the “little ice age”) which began long before the Maunder minimum and didn’t end until after the Maunder minimum was over. The idea that the Maunder minimum gave periods of unremitting cold is just wrong—it is often quoted but it is totally wrong. The claimed drop of 1.3°C in the Maunder minimum is a ludicrous figure. The Figure below (from Owens et al paper1) shows any drop that could possibly be associated with the Maunder minimum is 0.2 °C (and Owes et al show that is not statistically significant). That minimum was almost 1.3 °C lower than today’s values because of 1.1 °C of anthropogenic greenhouse warming since just before and just after the Maunder minimum. Figure – A comparison of solar activity and northern hemisphere climate from AD 800 to AD 2016. Top: Sunspot number, from direct telescopic observations (black) and reconstructed on the basis of 14C concentrations in tree trunks (red). Bottom: Northern hemisphere temperature anomaly, ΔT, (relative to the 1961–1990 mean) for paleoclimate reconstructions, as presented in the IPCC fifth assessment report. Colours, from white through red, show the probability density function (PDF), while the white line shows the PDF maximum value (or mode).The blue line shows ΔT from the instrumental record (HadCRUT4). (Source) 1- Owens et al (2017) The Maunder Minimum and the Little Ice Age: An update from recent reconstructions and climate simulations, Journal of Space Weather and Space Climate Georg Feulner Senior Scientist, Potsdam Institute for Climate Impact Research (PIK): [This comment taken from an evaluation of a similar statement.] While regional and seasonal effects might be larger, the expected global temperature response to a future grand solar minimum similar to the Maunder Minimum is a cooling of about 0.1°C. It should be pointed out that this cooling would occur on the background of current anthropogenic warming which is about a factor of 10 larger. To claim that temperatures will fall dramatically is thus not really justified. It is also clear from these numbers that a future grand solar minimum (which would last only for a few decades anyway) would not save us from global warming, as we have shown in a scientific paper and explained here. The marginal temperature differences between warming scenarios with and without a future Maunder Minimum is illustrated here: Figure – Rise of global temperature for two different emission scenarios (A1B, red, and A2, magenta). The dashed lines show the slightly reduced warming in case a Maunder-like solar minimum should occur during the 21st century. The blue line represents global temperature data. Source: PIK."
https://science.feedback.org/review/research-does-not-show-a-medieval-warm-period-warmer-than-the-present-day/,Inaccurate,"joannenova.com.au, Joanne Nova, 2019-07-26","18 proxies tell us the world was the same or warmer 1,000 years ago",,"Factually Inaccurate: Reconstructions of global temperature based on the available records indicate that the warmest period of the last 2,000 years is the current one. Flawed Reasoning: Finding individual records from single locations where temperatures were warmer 1,000 years ago would not demonstrate that these reconstructions of global temperature are incorrect.","Although periods of regional warming or cooling can be caused by natural variability (or events like volcanic eruptions), human-caused warming of the entire planet has led to the highest global temperatures of the last 2,000 years.","This new global temperature reconstruction by The Pages Consortium miraculously agrees with the models yet disagrees with hundreds of stalagmites, corals, ice cores, trees, lake sediments, mud from the ocean floor, pollen dust and 6,000 boreholes[...] 18 proxies tell us the world was the same or warmer 1,000 years ago",,"A recent study1 analyzing a global database of paleoclimate records found that no previous warm or cool period in the last 2,000 years—including the Roman Warm Period and the Medieval Warm Period (also called the Medieval Climate Anomaly)—occurred globally and synchronously. But 20th Century temperatures were the warmest of the last 2,000 years for nearly the entire surface of the Earth. These maps show the timing of the warmest temperatures in named warm periods (or coldest temperatures in named cool periods) over the last 2,000 years. Only the 20th Century warming is global in extent (top right).Source: Neukom et al (2019)1 1- Neukom et al (2019) No evidence for globally coherent warm and cold periods over the preindustrial Common Era, Nature Kevin Anchukaitis Associate Professor, The University of Arizona: [This comment is taken from a previous review of a similar claim.] 1) Our most up-to-date understanding of global mean temperatures is likely the Last Millennium Reanalysis1. Even accounting for uncertainties, global mean annual temperatures are higher now than any time in the last 2,000 years, with the middle of the 20th century either matching or exceeding Common Era temperatures as well. 2) For the Northern Hemisphere (where we have much better proxy data and a better understanding of the uncertainties), we come to similar conclusions—in Wilson et al (2016)2 we find that the two warmest decades of our reconstruction (from 918 to 2004 CE) were 1994–2003 and 1946–1955. Coming in 3rd place is 1161–1170 CE. So, the latest in large-scale temperature reconstructions do NOT support a claim that temperatures either in the Medieval or Roman periods were warmer than today. 3) Even if these periods were warmer than today (and we currently have no evidence that they were), that would have no bearing on whether CO2 is causing current warming. Current warming is unambiguously caused by CO2 emissions. Past warm and cold periods reflect a mix of internal climate system variability and changes in radiative forcing from volcanoes and solar variability. Current warming is the result of rising atmospheric CO2 concentration, whether or not there were past epochs of widespread warming. 1- Tardif et al (2019) Last Millennium Reanalysis with an expanded proxy database and seasonal proxy modeling, Climate of the Past 2- Wilson et al (2016) Last millennium northern hemisphere summer temperatures from tree rings: Part I: The long term context, Quaternary Science Reviews Rob Wilson Professor, University of St Andrews: [This comment is taken from a previous review of a similar claim.] Since 2015, several tree-ring based studies of large-scale Northern Hemisphere summer temperatures have shown that the last 10 or 20 year periods are significantly warmer than any other time for the last 1,200 years. A recent study in Nature1 has expanded on this work using a global multi-proxy data-set which suggests that the last 50 years have been warmer than any period of the last 2,000 years. The statement above is therefore incorrect and mis-characterises what is detailed in many studies. In fact, basic conclusions have been rather consistent over the past 20 years—i.e., recent warming is unprecedented for the last millennium (likely for last 2,000), the Sun has almost no detectable attributed impact on climate, and volcanoes have the strongest impact on climate prior to the anthropogenic period. Our knowledge of past climate is better where we have data and poor where we rely on teleconnections and/or interpolation. However, the paleoclimate community and users of the data we generate must appreciate that the 1st millennium of the Common Era is substantially much less constrained than the last 1,000 years and more effort and investment is needed to increase the number of climate proxy records for this earlier period (also the Medieval). Ideally, we should not mix proxy records that express different signals as the climate response to both internal and external forcing varies across different seasons (i.e., summer vs. winter). I would also contentiously add that for the late Holocene, we should minimise the use of proxy archives with poor (>10 years) resolution and substantial (+/- 5-10 years) dating uncertainties. 1- Neukom et al (2019) No evidence for globally coherent warm and cold periods over the preindustrial Common Era, Nature"
https://science.feedback.org/review/hosted-by-former-australian-senator-tony-heller-repeats-false-claim-that-scientists-fake-the-warming-trend/,Inaccurate,"EXOMATRIXTV, Tony Heller, 2019-07-20","[T]he raw data, the actual thermometer data[...] shows that the US has been cooling for 80 to 90 years. But the graphs they release to the public show warming trend, and it's all because they've altered the data.",,"Factually Inaccurate: Necessary adjustments to temperature datasets have, in total, reduced the apparent global warming trend since the late 1800s. Many independent datasets support the accuracy of these adjustments.","Scientists constantly work to ensure that the data being used to estimate global average temperatures are as accurate as possible—a necessary and much-studied task. Despite the fact that different groups have developed different methods to do this, the warming trend is clear in all available datasets.","Right on the NASA website, you can look and see in the year 2000 they showed about 0.5C total warming. In the year 2012, they pushed it up to about 0.9C warming. Now they show about almost 1.5C warming over lands[...] [T]he raw data, the actual thermometer data, which comes from this incredible network of very good, contiguous 1,200 stations in the US, shows that the US has been cooling for 80 to 90 years. But the graphs they release to the public show warming trend, and it's all because they've altered the data.",,"Differences between versions of NASA’s global temperature dataset can easily be viewed on the NASA website. Source: NASA The most significant adjustments to data relate to changing ship-based instruments and methods used to measure sea surface temperatures around the time of World War II. As the use of thermometers in buckets of water hauled up on deck was replaced by thermometers in ship engine water intake pipes, the measured temperatures changed slightly, necessitating a correction to ensure an “apples-to-apples” comparison. Datasets operated by NOAA in the US, the UK Met Office, and others match and support NASA’s results. Upper panel: NOAA (red), NASA (blue), UK Met Office (green), and Berkeley Earth (yellow) datasets.Bottom panel: NOAA (red), NASA (green), and UK Met Office (blue) datasets.Source: US NCA Mark Richardson Research Associate, Colorado State University/NASA JPL: [This comment was initially provided as part of a claim review.] Raw data show more global warming since 1880 than is reported by NOAA [or shown in other datasets]. This is because NOAA “adjusts” temperature data to fairly compare different measurement times, places, and technologies. The cooling effect of adjustments on global temperatures has been shown lots of times, such as with the graph below for 1880—2013 temperatures. A small group of conspiracy theorists flip this reality by “cherry picking”, which means using a fraction of the data to prop up claims that are false globally. It’s the sort of technique that would insist that this is a 100% blue cherry tree. NOAA scientists know that afternoons tend to be warmer than early mornings so it would be dumb to mix, for example, 1940s morning temperature readings with 2010s afternoon readings without accounting for this. They refuse to do obviously, provably dumb things so they carefully correct the data for a fair comparison. In the U.S., thermometers used to be read largely in the afternoon but now tend to be read in the morning1. This means that adjustments in the U.S. are warming, making it a popular choice for hints at conspiracy. There are ways to judge whether new claims are credible. Firstly, do they mention that global adjustments are cooling overall? Secondly, do they discuss reasons for adjustments including measurement time? If the answer is “no” to either then the author is hiding relevant information or is clueless about the topic and you should be very sceptical. Fortunately the scientific method can reliably test new claims through submissions to scientific journals for peer review, which tends to filter out obvious dumb mistakes like ignoring how afternoons are warmer than early mornings. Blog posts, think tanks and newspapers have no such filter. We know that NOAA’s adjustments improve things since they’re tested and updated whenever issues are found. For example, even a blogger who’s hostile to climate science results published a paper confirming that the NOAA U.S. average temperature changes are solid2. Another study by an independent “red team”, partly funded by a Koch foundation, supported NOAA’s conclusions3. I was involved with a check of NOAA’s ocean record using infrared scans from satellites4. The satellites supported NOAA’s results despite baseless & hysterical accusations that had been thrown at the scientists. After more than a decade of being relentlessly wrong, it’s time to be very careful with any new conspiracy claims aimed at the temperature records. 1-Vose et al (2003) An evaluation of the time of observation bias adjustment in the U.S. Historical Climatology Network, Geophysical Research Letters 2-Fall et al (2011) Analysis of the impacts of station exposure on the U.S. Historical Climatology Network temperatures and temperature trends, Journal of Geophysical Research: Atmospheres 3-Rohde et al (2012) A New Estimate of the Average Earth Surface Land Temperature Spanning 1753 to 2011, Geoinformatics & Geostatistics: An Overview 4-Hausfather et al (2017) Assessing recent warming using instrumentally homogeneous sea surface temperature records, Science Advances Victor Venema Scientist, University of Bonn, Germany: [These comments were initially provided as part ofan article review.] To estimate how much the world has warmed, other changes need to be removed from the observations made at weather stations, observing ships and buoys. For example, if the surrounding of a station becomes more urban this often causes a warming that is local and needs to be removed to estimate the amount the world has truly warmed. Similarly when such a station moves to a better location, which is cooler, such a cooling jump needs to be removed for an accurate warming estimate. When it comes to the global mean temperature the main effect that needs to be removed is that in the past many sea surface temperature observations were made by hand with buckets and nowadays are made automatically at the water inlet of ships. While the water is hauled on deck and the thermometer adapts to the water temperature, the sea water evaporates and cools. Old measurements are thus 0°C to 0.4°C (0.7°F) too cold. Source: UK MetOffice In the unscientific formulation of [some], this means that the adjustments for this effect make the past warmer and the recent temperatures colder. But overall, the estimated global warming actually becomes smaller when taking into account all the adjustments—the opposite of [that claim]. [See figure in Mark Richardson’s comment above.] The adjustments climatologists make for land station data do make the warming greater. But the ocean adjustments (which reduce the warming trend) are more important for the global average. How large the adjustments need to be depends on how many other changes there were. The adjustments in the United States of America are relatively large, mainly due to two effects. In the past the thermometers were read more often in the afternoon, while nowadays they are read more often in the morning. The estimates of the daily average temperature based on minimum and maximum temperature thermometers are a bit colder in the morning than in the afternoon. A particularly cold morning can affect the observed minimum temperature of two days and a very hot afternoon the maximum temperature of two days. The temperature used to be measured with a thermometer in a Cotton Region Shelters in the USA. Nowadays they are mostly made using an Automatic Weather Station. These Automatic Weather Stations on average measure a lower temperature because they heat up less standing in the sun. The difference is especially large for the maximum temperature and for the summer. Comparing old summer maximum temperature with those of today would not be comparing like with like. And even if we had not invented the thermometer we would know it is warming: Glaciers are melting, from the tropical Kilimanjaro glaciers, to the ones in the Alps and Greenland. Arctic sea ice is shrinking. The growing season in the mid-latitudes has become weeks longer. Trees bud and blossom earlier. Wine grapes can be harvested earlier. Animals migrate earlier. The habitat of plants, animals and insects is shifting poleward and up the mountains. Lakes and rivers freeze later and break up the ice earlier. The oceans are rising."
https://science.feedback.org/review/nbc-news-story-accurately-covers-research-on-two-millennia-of-climate-history-jaclyn-jeffrey-wilensky/,1.3,"NBC News, by Jaclyn Jeffrey-Wilensky, on 2019-07-24.",,"""Climate scientists drive stake through heart of skeptics' argument""",,,,,"A recent study working with a global database of paleoclimate records found that no previous warm or cool period in the last 2,000 years—including the Roman Warm Period and the Medieval Warm Period (also called the Medieval Climate Anomaly)—occurred globally and synchronously. But 20th Century temperatures were the warmest of the last 2,000 years for nearly the entire surface of the Earth. These maps show the timing of the warmest temperatures in named warm periods (or coldest temperatures in named cool periods) over the last 2,000 years. Only the 20th Century warming is global in extent (top right).Source: Neukom et al (2019)1 Another study examined the later portion of a period known as the “Little Ice Age”, finding that regional patterns of cooling resulted from a series of major volcanic eruptions in the early 1800s. Scientists who reviewed the article found that it accurately summarized these new studies, although the headline is somewhat dramatic.See all the scientists’ annotations in context. You can also install the Hypothesis browser extension to read the scientists’ annotations in context.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Mark Richardson Research Associate, Colorado State University/NASA JPL: This accurately describes new peer-reviewed research and asks independent scientists with relevant expertise to provide important context, such as how these results rely on limited southern hemisphere data. Simplifications help readers understand important points without misleading them. Mark Eakin Scientist, Coordinator of NOAA’s Coral Reef Watch, National Oceanic and Atmospheric Administration: I would ding it to a little lower than a 2 for the overly-dramatic headline (“Climate scientists drive stake through heart of skeptics’ argument”). Statements in the article are correct and provide active links to the original publications. Peter Kalmus Data Scientist, Jet Propulsion Laboratory: While I think we already knew the main findings of this pair of studies with confidence, these studies bump that confidence up another notch. This article does a good job with basic reporting on the studies. However, the article misleads by framing the story (via headline and intro) as if there were previously any possibility that climate deniers—who are inaccurately referred to here as “skeptics”—were not as wrong as wrong can be. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time."
https://science.feedback.org/review/the-earth-was-not-warmer-in-medieval-times-town-hall-gregory-rummo/,Inaccurate,"Townhall, Gregory Rummo, 2019-07-23","Earth’s mean temperature over the last 2,000 years shows two previous periods when temperatures were warmer than they are now; from 1–200 A.D., an epoch called the Roman Warm Period, and more recently the Medieval Warm Period from 900–1100 A.D.",,"Factually Inaccurate: Available climate records show that recent global temperatures are likely the highest of the last 2,000 years and there is no data supporting the claim that, globally, the Earth was warmer during the Roman or Medieval eras.  Flawed Reasoning: Natural climate change events in the past do not provide evidence that human emissions of greenhouse gas are incapable of changing the climate today.","It's not true that the world has been warmer at other times during the last 2,000 years. But even if that were the case, it would not change the fact that human emissions of greenhouse gases are causing Earth's climate to warm.","A graph of the Earth’s mean temperature over the last 2,000 years shows two previous periods when temperatures were warmer than they are now; from 1–200 A.D., an epoch called the Roman Warm Period, and more recently the Medieval Warm Period from 900–1100 A.D.[…] It is worth noting that both of these climate optima occurred centuries before the discovery of fossil fuels and the invention of the internal combustion engine.",,"UPDATE (31 July 2019): Following a correction posted by 27 July, Townhall has now retracted this article, replacing it with this short message: “An earlier version of this column incorrectly cited a graph of the Earth’s mean temperature over the last 2,000 years showing two previous periods when temperatures were warmer than they are now; from 1–200 A.D., an epoch called the Roman Warm Period, and more recently the Medieval Warm Period from 900–1100 A.D.” You can read the updated version here and the original version here.A recent study1working with a global database of paleoclimate records found that no previous warm or cool period in the last 2,000 years—including the Roman Warm Period and the Medieval Warm Period (also called the Medieval Climate Anomaly)—occurred globally and synchronously. But 20th Century temperatures were the warmest of the last 2,000 years for nearly the entire surface of the Earth. These maps show the timing of the warmest temperatures in named warm periods (or coldest temperatures in named cool periods) over the last 2,000 years. Only the 20th Century warming is global in extent (top right).Source: Neukom et al (2019)1 Warming/cooling rates averaged across 51 years and based on paleoclimate records. Modern thermometer records shown in black.Source: University of Bern 1- Neukom et al (2019) No evidence for globally coherent warm and cold periods over the preindustrial Common Era, Nature Kevin Anchukaitis Associate Professor, The University of Arizona: 1) It is entirely unclear what graph (“A graph of the Earth’s mean temperature over the last 2,000 years”) the author of the op-ed is referring to (it doesn’t appear to be included or appear in the op-ed). 2) Our most up-to-date understanding of global mean temperatures is likely the Last Millennium Reanalysis1. Even accounting for uncertainties, global mean annual temperatures are higher now than any time in the last 2,000 years, with the middle of the 20th century either matching or exceeding Common Era temperatures as well. 3) For the Northern Hemisphere (where we have much better proxy data and a better understanding of the uncertainties), we come to similar conclusions—in Wilson et al (2016)2 we find that the two warmest decades of our reconstruction (from 918 to 2004 CE) were 1994–2003 and 1946–1955. Coming in 3rd place is 1161–1170 CE. So, the latest in large-scale temperature reconstructions do NOT support a claim that temperatures either in the Medieval or Roman periods were warmer than today. 4) Even if these periods were warmer than today (and we currently have no evidence that they were), that would have no bearing on whether CO2 is causing current warming. Current warming is unambiguously caused by CO2 emissions. Past warm and cold periods reflect a mix of internal climate system variability and changes in radiative forcing from volcanoes and solar variability. Current warming is the result of rising atmospheric CO2 concentration, whether or not there were past epochs of widespread warming. 1- Tardif et al (2019) Last Millennium Reanalysis with an expanded proxy database and seasonal proxy modeling, Climate of the Past 2- Wilson et al (2016) Last millennium northern hemisphere summer temperatures from tree rings: Part I: The long term context, Quaternary Science Reviews Rob Wilson Professor, University of St Andrews: Since 2015, several tree-ring based studies of large-scale Northern Hemisphere summer temperatures have shown that the last 10 or 20 year periods are significantly warmer than any other time for the last 1,200 years. A recent study in Nature1 has expanded on this work using a global multi-proxy data-set which suggests that the last 50 years have been warmer than any period of the last 2,000 years. The statement above is therefore incorrect and mis-characterises what is detailed in many studies. In fact, basic conclusions have been rather consistent over the past 20 years—i.e., recent warming is unprecedented for the last millennium (likely for last 2,000), the Sun has almost no detectable attributed impact on climate, and volcanoes have the strongest impact on climate prior to the anthropogenic period. Our knowledge of past climate is better where we have data and poor where we rely on teleconnections and/or interpolation. However, the paleoclimate community and users of the data we generate must appreciate that the 1st millennium of the Common Era is substantially much less constrained than the last 1,000 years and more effort and investment is needed to increase the number of climate proxy records for this earlier period (also the Medieval). Ideally, we should not mix proxy records that express different signals as the climate response to both internal and external forcing varies across different seasons (i.e., summer vs. winter). I would also contentiously add that for the late Holocene, we should minimise the use of proxy archives with poor (>10 years) resolution and substantial (+/- 5-10 years) dating uncertainties. 1- Neukom et al (2019) No evidence for globally coherent warm and cold periods over the preindustrial Common Era, Nature"
https://science.feedback.org/review/sky-news-australia-interview-falsely-claims-that-global-cooling-is-coming-soon/,Incorrect,"Sky News Australia, Alan Jones, Nils Axel-Mörner, 2019-06-17","the Intergovernmental Panel on Climate Change is misleading humanity about climate change and sea levels, and that in fact a new solar-driven cooling period is not far off",,Inadequate Support: These claims contradict all the available data and published research on these topics. There is no support in the scientific literature for the claim that solar activity could significantly cool the climate in the decades to come.,"Scientists have established that observed climate change and sea level rise are clearly caused by human activities, primarily the emission of carbon dioxide through the burning of fossil fuels. Solar activity cannot explain recent warming, and even the occurrence of low solar activity in the near future would have an insignificant effect on human-caused warming.","[Nils Axel-Mörner] is saying that the Intergovernmental Panel on Climate Change is misleading humanity about climate change and sea levels, and that in fact a new solar-driven cooling period is not far off [...] You're saying it's solar activity which is the dominant factor and not carbon dioxide? 'Yes, for sure.'",,"This video has been widely shared on YouTube (where it currently has nearly 250,000 views) as well as Facebook (with 15,000 shares in June and July). Both Sky News Australia host Alan Jones and his guest Nils Axel-Mörner make a variety of claims about climate change and climate science, with this quote representing the claims that observed climate change has been caused by changes in solar activity rather than human activities, and that a decline in solar activity is coming that will cause global cooling in the near future. Both claims contradict the peer-reviewed research on these topics, and the available evidence. Scientists who study the causes of 20th Century climate change incorporate solar activity data. The 2013 IPCC report’s summary of this research, for example, gathered estimates of these “climate forcings”, represented in the figure below. Solar activity can explain very little of the long-term warming trend (and none of the warming trend since the 1950s, when solar activity began to decline slightly), while human activities are the dominant warming factor. Estimates of climate forcings (factors that can drive a change in global temperature). “Total anthropogenic” includes all human-caused forcings, while changes in the Sun are shown at the bottom. Source: IPCC As explained in the scientists’ comments below, there is no evidence that a future period of low solar activity could overcome human-caused warming and lead to a decline in global average temperature. Georg Feulner Senior Scientist, Potsdam Institute for Climate Impact Research (PIK): [This comment is taken from an earlier review of a similar statement.] While regional and seasonal effects might be larger, the expected global temperature response to a future grand solar minimum similar to the Maunder Minimum is a cooling of about 0.1°C. It should be pointed out that this cooling would occur on the background of current anthropogenic warming which is about a factor of 10 larger. To claim that “temperatures will fall dramatically” is thus not really justified1,2,3. It is also clear from these numbers that a future grand solar minimum (which would last only for a few decades anyway) would not save us from global warming, as we have shown in a scientific paper4and explained here. The marginal temperature differences between warming scenarios with and without a future Maunder Minimum is illustrated here: Figure – Rise of global temperature for two different emission scenarios (A1B, red, and A2, magenta). The dashed lines show the slightly reduced warming in case a Maunder-like solar minimum should occur during the 21st century. The blue line represents global temperature data. Source: PIK. 1- Anet et al (2013) Impact of a potential 21st century “grand solar minimum” on surface temperatures and stratospheric ozone. Geophysical Research Letters [“although the solar minimum results in a reduced global warming, it cannot compensate continuing anthropogenic impacts.“] 2- Meehl (2013) Could a future “Grand Solar Minimum” like the Maunder Minimum stop global warming?Geophysical Research Letters [“a future grand solar minimum could slow down but not stop global warming.“] 3- Jones et al (2012) What influence will future solar activity changes over the 21st century have on projected global near-surface temperature changes?Journal of Geophysical Research Atmospheres. [“the possible mitigation potential for future solar activity changes is much smaller than the known uncertainties and ranges in the future anthropogenic response.“] 4- Feulner and Rahmstorf (2010) On the effect of a new grand minimum of solar activity on the future climate on Earth, Geophysical Research Letters Patrick Brown Assistant Professor, San Jose State University: [This comment is taken from an earlier review of a similar statement.] In addition to increases in CO2, there was a slight increase in total solar irradiance over the early 20th century and a transition from a period of relatively active volcanic activity to a period of little volcanic activity (both of which would have contributed warming over the early 20th century). The remainder of the warming is within the envelope expected from natural unforced internal variability and there is reason to believe that changes in the Atlantic Multidecadal Oscillation and Pacific Decadal Oscillation combined to warm global temperatures over the period. In a recent review, Hegerl et al. (2018)1 suggest that about half of early 20th-century warming was caused by external forcings like increasing greenhouse gasses, solar activity and volcanic activity while the other half may have been due to internal unforced variability from changes in the Atlantic Multidecadal Oscillation and Pacific Decadal Oscillation: Top: Factors influencing global temperature.Bottom: Estimates of natural oscillations in the Atlantic (AMO) and Pacific (PDO) Oceans.Source: Hegerl et al (2018)1 Careful analysis that attempts to take into account all major factors and their evolution in time indicates that anthropogenic increases in greenhouse gasses account for more than 100% of the observed warming on the century timescale (requiring cancellation from cooling influences). See the summary graphic from Carbon Brief, below. Source: Carbon Brief 1-Hegerl et al (2018) The early 20th century warming: Anomalies, causes, and consequences, WIREs Climate Change"
https://science.feedback.org/review/non-peer-reviewed-manuscript-falsely-claims-natural-cloud-changes-can-explain-global-warming/,Incorrect,"Zero Hedge, Summit.news, Sky News Australia, Fox News, Paul Joseph Watson, Pekka Malmi, Jyrki Kauppinen, 2019-07-11",During the last hundred years the temperature is increased about 0.1°C because of carbon dioxide. The human contribution was about 0.01°C.,,"Flawed Reasoning: The authors' argument claims a correlation between cloud cover/relative humidity and global temperature proves that the former caused the latter without investigating whether they have the relationship backwards. Inadequate support: The source of their claimed global cloud dataset is not given, and no research on their proposed mechanism for climate change is cited. Fails to provide correct physical explanation: The manuscript incorrectly claims that the rise of atmospheric carbon dioxide is caused by release from ocean waters. It also provides no explanation for the claim that an increase in relative humidity causes global cooling.",Warming related to human activities is estimated to be around 1°C over the past century. This document claims to overturn decades of scientific findings but provides neither the source of the data it uses nor the physics responsible for the proposed relationship between clouds and global temperature.,Man-made Climate Change Doesn't Exist In Practice... During the last hundred years the temperature is increased [sic] about 0.1°C because of carbon dioxide. The human contribution was about 0.01°C.,,"Some news outlets are publishing articles stating that this claim is based on a new study. In reality, there is no new published study. The claim comes from a six-page document uploaded to arXiv, a website traditionally used by scientists to make manuscripts available before publication. This means that this article has not been peer-reviewed, so there is no guarantee to its credibility. If the blogs that covered this as a new study had contacted independent scientists for insight, instead of accepting this short document as revolutionary science, they would have found that it does not have any scientific credibility. As the scientists who examined this claim explained, the document relies on circular reasoning to claim that cloud cover and relative humidity have caused the change in global temperature, and ignores many additional factors affecting global temperature—including aerosol pollution, volcanic eruptions, and natural ocean oscillations. The published, peer-reviewed scientific research on this topic clearly shows that human activities are responsible for climate change. Timothy Osborn Professor, University of East Anglia, and Director of Research, Climatic Research Unit: The unpublished paper by Kauppinen & Malmi is deeply flawed and the claims that (1) CO2 has caused only 0.1 degC of warming and that (2) only 10% (0.01 degC) of this warming is from human activity are both unsupported claims. The paper should not be relied upon. Their claims are based on a chain of reasoning with multiple flaws: (1) They claim that climate models cannot be relied upon but do not demonstrate this. (2) They instead make a new climate model (despite this being in contradiction of (1)). (3) Their new climate model is unvalidated. It is based upon datasets of cloud and humidity without any sources given and which are not up-to-date. They provide no assessment of the accuracy of the data used—these variables are very difficult to measure on a global basis over the time period used. No physical basis is given for their new climate model (e.g. no process is given for how higher relative humidity can make the globe cool). (4) They fail to consider cause and effect. For example, they assume without any support that a decrease in relative humidity is natural. They give no reasons why it would have decreased. They fail to consider whether climate change could have caused relative humidity to change. (5) They state without any support that most of the atmospheric CO2 increase is due to emissions from the oceans. They ignore anthropogenic CO2 emissions which are more than large enough to explain the full increase. They ignore observational evidence that shows that the oceans are net sinks of CO2 at present, not net sources. (6) They dismiss the entire body of climate science—especially that there is a significant greenhouse effect—and instead cite their own work (unpublished or published in journals outside the field). In reality there is strong scientific evidence for conclusions in stark contrast to those of Kauppinen and Malmi, namely that (a) all of the CO2 rise is from human activity, (b) that 100% of the CO2-induced warming is therefore anthropogenic, and (c) that (together with anthropogenic emissions of other greenhouse gases like methane) the total anthropogenic warming is around 1 degC. A published paper demonstrating (a) and (b) is Cawley (2011)1. A body of evidence for (c) is Haustein et al (2017)2 and references therein. 1- Cawley (2011) On the Atmospheric Residence Time of Anthropogenically Sourced Carbon Dioxide, Energy & Fuels 2- Haustein et al (2017) A real-time Global Warming Index, Scientific Reports Richard Betts Professor, Met Office Hadley Centre & University of Exeter: This document is not a proper scientific paper and would not pass peer review in an academic journal. The crucial data sources (e.g. of the dataset claimed to be low cloud cover) are not provided, and the figure purporting to show changes in cloud cover is at odds with peer-reviewed papers like Eastman et al1. That published scientific paper does not show the decline in low cloud cover claimed in this document. Annual average daytime cloud cover. Source: Eastman et al (2011) This document only cites 6 references, 4 of which are the authors’ own, and of these 2 are not actually published. Therefore I would not regard this document as having any scientific credibility. Even if the claimed observational cloud data turned out to be of good quality, the authors inaccurately describe figure 2 as “experimental observations”. “Experimental” would imply that it was derived by experiment: i.e., some sort of controlled scientific study, as opposed to observations of the uncontrolled natural world. (Unless they are claiming to have carried out an actual experiment on the Earth, which would be a bizarre claim!). All they are doing is correlating two datasets (of unknown source). This does not “prove” anything, despite their claims that it does. Their overall conclusion of small anthropogenic contribution to observed global warming is very different to the conclusions of numerous properly-documented scientific studies2, which have demonstrated beyond reasonable doubt that the observed warming in recent decades is due to human influence. 1- Eastman et al (2011) Variations in Cloud Cover and Cloud Types over the Ocean from Surface Observations, 1954–2008, Journal of Climate 2- IPCC (2013) Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, Chapter 10 Chris Brierley Senior Lecturer, University College London: From a logic perspective, this effort makes two utterly unjustified assumptions: (1) That any changes in low cloud cover are natural, rather than human-induced. The research discipline of aerosol-cloud interactions exists to explore this relationship; and the charlatans selling cloud-seeding would argue vociferously against all cloud changes being natural. (2) Correlation = causality. Just because two time series show a strong correlation, does not mean that one causes the other. In fact, I’ve no idea why the authors think reducing cloud cover drives warming, rather than the over way around. The IPCC report, (Boucher et al1, cited by them) states that warming causes low cloud cover. An enlightening example to highlight this kind of error is the correlation between the number of storks and birth rate in Europe2. But this article also misses some important hallmarks of real science: (1) It gives only one reference to research by other scientists. (2) Even this is a mis-application: they authors neglect to include any time-variation in their equation. This effectively assumes that the Earth responds instantaneously to any drivers. (3) They explicitly state at the outset that they do not consider models as evidence. (4) They do not explain where their data has come from (I guess though that the cloud cover has come from satellite irradiance, processed through a model). (5) They infer meaning well-beyond the scope of their data, without any justification. 1- Boucher et al (2013) Clouds and aerosols. In Climate change 2013: the physical science basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change 2- Matthews (2000) Storks deliver babies (p= 0.008), Teaching Statistics Mark Richardson Research Associate, Colorado State University/NASA JPL: Errors in this manuscript include: (1) The climate model comparison shows the opposite of what Kaupinen & Malmo claim. (2) Their assumed warming effects of CO2 are much smaller than we’ve measured. (3) They say that clouds and humidity are causing all the temperature change but satellite measurements suggest, if anything, the opposite. (4) Humans caused the CO2 rise and the oceans are absorbing CO2, this is changing ocean pH. Kaupinen and Malmi falsely say the opposite: that oceans are adding CO2 to the air. There’s tons of observational evidence that human activity is driving global warming, and this data supports the projected range of ongoing and future global warming. The Kaupinen and Malmi conclusions are based on misrepresenting research, ignoring most of the evidence, correlating things then mixing up what causes what, and using false numbers. Climate models simplify and apply the laws of physics to calculate Earth’s climate. Include human pollution since 1880 and they show global warming as observed, but if you only include natural changes (e.g. in the Sun and volcanoes) they calculate almost no warming. Kaupinen and Malmi’s article is totally confused and thinks this shows that the models can’t be trusted. It actually shows that if our physics is right then most observed warming is due to human activity. The biggest single factor is increasing carbon dioxide (CO2) levels in the air. This is a gas that traps infrared heat trying to escape Earth and warms us up. Venus has many times more CO2, and it’s the main reason its surface is hot enough to melt lead. We’ve measured CO2 heating Earth1,2 and Planck’s Law tells us that this would directly warm Earth by about 300% more than assumed by Kaupinen and Malmi3. Most of their article talks about changes in clouds and humidity. Physics tell us what to expect from clouds, and satellites have measured these changes4,5. We’ve also measured tropical clouds getting higher6, low clouds retreating when it warms7, and changes in ice and liquid mixtures in clouds8. Newer work shows that cloud changes and how they insulate Earth and reflect sunlight can be calculated and predicted from changing temperature patterns9,10,11,12, i.e., the temperature patterns can mostly explain monthly cloud changes instead of the other way around. Finally, after using a bunch of nonsense calculations to say that 0.1 °C warming is from CO2, they say that 90% of the change in CO2 is caused by the oceans. This violates conservation of mass from basic chemistry13: the oceans are actually absorbing CO214,15 which, again, is the complete opposite of what Kaupinen and Malmi claim. Without claiming the opposite of reality, their conclusions cannot be supported. 1- Feldman et al (2015) Observational determination of surface radiative forcing by CO2 from 2000 to 2010, Nature 2- Harries et al (2001) Increases in greenhouse forcing inferred from the outgoing longwave radiation spectra of the Earth in 1970 and 1997, Nature 3- Soden et al (2008) Quantifying Climate Feedbacks Using Radiative Kernels, Journal of Climate 4- Yue et al (2019) Temporal and Spatial Characteristics of Short-term Cloud Feedback on Global and Local Interannual Climate Fluctuations from A-Train Observations, Journal of Climate 5- Zelinka et al (2016) Insights from a refined decomposition of cloud feedbacks, Geophysical Research Letters 6- Norris et al (2016) Evidence for climate change in the satellite cloud record, Nature 7- Brient and Schneider (2016) Constraints on Climate Sensitivity from Space-Based Measurements of Low-Cloud Reflection, Journal of Climate 8- Tan et al (2016) Observational constraints on mixed-phase clouds imply higher climate sensitivity, Science 9- Andrews et al (2018) Accounting for Changing Temperature Patterns Increases Historical Estimates of Climate Sensitivity, Geophysical Research Letters 10- Dong et al (2019) Attributing Historical and Future Evolution of Radiative Feedbacks to Regional Warming Patterns using a Green’s Function Approach: The Preeminence of the Western Pacific, Journal of Climate 11- Silvers et al (2018) The Diversity of Cloud Responses to Twentieth Century Sea Surface Temperatures, Geophysical Research Letters 12- Zhou et al (2016) Impact of decadal cloud variations on the Earth’s energy budget, Nature Geoscience 13- Richardson (2013) Comment on “The phase relation between atmospheric carbon dioxide and global temperature” by Humlum, Stordahl and Solheim, Global and Planetary Change 14- Hartfield et al (2018) State of the Climate in 2017, Bulletin of the American Meteorological Society 15- Lauvset et al (2015) Trends and drivers in global surface ocean pH over the past 3 decades, Biogeosciences Victor Venema Scientist, University of Bonn, Germany: This text may look like a scientific article to a lay-person, but I would not accept it as a bachelor thesis. It does not cite its data sources, it does not discuss the uncertainties in the data, nor does it discuss that other cloud data sets find the opposite trend. It does not explain sufficiently how computations were made to make the study reproducible and understandable. It does not discuss the conflict between its claimed low climate sensitivity and climatic changes in the (deep) past. It cites six references: one to the IPCC report and one scientific article, both of which they apparently did not read or understand; two of their own unpublished manuscripts and two of their own articles in questionable or predatory journals. Still even if we would grant this work to show that climate models do not give the right estimates of climate sensitivity, it would still not show that the Earth has a low climate sensitivity. There are several independent lines of evidence which give us estimates of the climate sensitivity, only one of which is climate models. A summary of this evidence can be found in the figure below from the last IPCC, which the authors cite. [Additional comments available as Hypothes.is annotations on the original pdf.] Estimates of climate sensitivity from studies of different types. Source: IPCC Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: It’s not clear how to respond to disingenuous summaries of an unpublished paper regarding global warming written by authors that appear to have limited training in climate science. The websites that have promoted this paper provide no counterpoint or basic fact checking on the bold claims made by the authors. The websites mislead readers regarding the well-documented scientific consensus that human activities have made a substantial contribution to the observed warming of the Earth’s surface. The paper itself is flawed: it doesn’t provide sufficient methodological details, including the datasets used in the study, misrepresents basic, well-accepted information about climate change, and ignores research studies undertaken by climate scientists. The main claim is based on a correlation: that as the Earth warms, low clouds disappear. The authors’ narrative is that low clouds are decreasing due to some natural cause (no mechanism provided by the authors) and the disappearance of low clouds then results in surface warming. This is akin to claiming that increased ice cream sales leads to warmer temperatures. In reality, the feedback is a known and documented phenomenon and works the other way: as the surface of the Earth warms, low cloud coverage decreases, allowing more sunlight to reach and warm the Earth’s surface. Global temperature datasets, developed by a number of independent research groups, show robust warming in the troposphere and at the Earth’s surface. The radiative effect of carbon dioxide has also been observed1. Considering multiple lines of evidence, the IPCC concluded that it is “extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century.” More recent analysis of satellite data shows that tropospheric warming from the satellite record is pronounced and cannot be explained by natural climate variability alone2. 1-Feldman et al (2015) Observational determination of surface radiative forcing by CO2 from 2000 to 2010, Nature 2-Santer et al (2017) Tropospheric Warming Over The Past Two Decades, Scientific Reports Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: [This comment comes from a previous review of a similar claim.] As we demonstrated in our recent Journal of Climate paper1, you don’t necessarily need internal variability to explain early 20th century warmth; a combination of increasing greenhouse gas concentrations, solar output, and a reduction in volcanic activity can explain most of the observed changes during that period: Source: CarbonBrief This is an area of active research, and other estimates (e.g. from Hegerl et al, 20182) suggest that natural variability could contribute around 50% of the warming during that period. But no one suggests that early 20th century warmth was solely due to natural variability. Many of the natural factors that played a role in early 20th century warmth, such as increased solar output, have been moving the other direction over the past 50 years. Natural factors alone would have resulted in cooling rather than warming over the past few decades: Observed temperature compared to (left) climate model simulations that include human activities and (right) climate model simulations with natural factors only. Source: US NCA Patrick Brown Assistant Professor, San Jose State University: [This comment comes from a previous review of a similar claim.] Careful analysis that attempts to take into account all major factors and their evolution in time indicates that anthropogenic increases in greenhouse gasses account for more than 100% of the observed warming on the century timescale (requiring cancellation from cooling influences). See the summary graphic from Carbon Brief, below. Source: Carbon Brief "
https://science.feedback.org/review/on-fox-news-patrick-michaels-falsely-claims-humans-are-only-responsible-for-half-of-global-warming/,Incorrect,"Fox News, Patrick Michaels, 2018-10-21","So that means that probably about half, maybe half of that nine-tenths of the degree [of total warming] might be caused by greenhouse gases",,"Misleading: Human-caused warming did not begin in 1976, as Michaels claims.  Inadequate support: No evidence or research is provided to support this claim, which contradicts the published scientific literature.","Multiple factors—some human-caused and some natural—combine to influence global temperatures. However, human activities were already causing warming in the first half of the 20th century, and are responsible for approximately 100% of the more-rapid warming taking place after 1950. Thus, humans are responsible for most of the warming since 1900.","There are two periods of warning, one in the early 20th Century that could not have been caused by human beings because we hadn't put enough CO2 in the air, and one in the later part of the 20th Century that either slows down or ends depending upon whose data you use somewhere in the late 1990s, only to resume with the big El Nino that covered the news the last couple of years.  So that means that probably about half, maybe half of that nine-tenths of the degree [of total warming] might be caused by greenhouse gases because when the planet warmed beginning in 1976, the temperature of the stratosphere started to drop and that's the prediction of greenhouse theory","1- Haustein et al (2019) A limited role for unforced internal variability in 20th century warming, Journal of Climate 2- Hegerl et al (2018) The early 20th century warming: Anomalies, causes, and consequences, WIREs Climate Change 3- Callendar (1938) The artificial production of carbon dioxide and its influence on temperature, Quarterly Journal of the Royal Meteorological Society 4- Thompson et al (2008) A large discontinuity in the mid-twentieth century in observed global-mean surface temperature, Nature ","This claim is being reviewed months after the interview first ran because it has recently been recirculated by blogs dismissive of climate science, and has been one of the most highly promoted videos by YouTube’s suggestion algorithm in recent weeks. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: Pat Michaels is incorrect in his assertion that early 20th century warming somehow reduces the role for CO2 and other greenhouse gases in the rapid warming the world has experienced over the past few decades. Early 20th century warming was more gradual and much shorter than what we have experienced over the past 50 years. As we demonstrated in our recent Journal of Climate paper1, you don’t necessarily need internal variability to explain early 20th century warmth; a combination of increasing greenhouse gas concentrations, solar output, and a reduction in volcanic activity can explain most of the observed changes during that period: Source: CarbonBrief This is an area of active research, and other estimates (e.g. from Hegerl et al, 20182) suggest that natural variability could contribute around 50% of the warming during that period. But no one suggests that early 20th century warmth was solely due to natural variability. Many of the natural factors that played a role in early 20th century warmth, such as increased solar output, have been moving the other direction over the past 50 years. Natural factors alone would have resulted in cooling rather than warming over the past few decades: Observed temperature compared to (left) climate model simulations that include human activities and (right) climate model simulations with natural factors only. Source: US NCA Michaels is similarly misleading in asserting that warming “either slows down or ends” in the mid-1990s. That is clearly not the case; not only is no significant slowdown apparent after 1990, but the past few years have been near record-warm despite modest La Nina conditions. Source: CarbonBrief Patrick Brown Assistant Professor, San Jose State University: Using NASA GISTEMP, it is closer to 1.2°C warming over the past 100 years. Humans were, in fact, increasing greenhouse gasses sufficiently in the early 20th century such that it had an influence on global temperature. This was acknowledged even at the time. Guy Callendar estimated the influence of anthropogenic CO2 on global temperature in a paper in 19383 which reads: “…the increase in mean temperature, due to the artificial production of carbon dioxide, is estimated to be at the rate of 0.003°C. per year at the present time.” In addition to increases in CO2, there was a slight increase in total solar irradiance over the early 20th century and a transition from a period of relatively active volcanic activity to a period of little volcanic activity (both of which would have contributed warming over the early 20th century). The remainder of the warming is within the envelope expected from natural unforced internal variability and there is reason to believe that changes in the Atlantic Multidecadal Oscillation and Pacific Decadal Oscillation combined to warm global temperatures over the period. In a recent review, Hegerl et al. (2018)2 suggest that about half of early 20th-century warming was caused by external forcings like increasing greenhouse gasses, solar activity and volcanic activity while the other half may have been due to internal unforced variability from changes in the Atlantic Multidecadal Oscillation and Pacific Decadal Oscillation: Top: Factors influencing global temperature.Bottom: Estimates of natural oscillations in the Atlantic (AMO) and Pacific (PDO) Oceans.Source: Hegerl et al (2018)2 Measurement error could also play a role. Thompson et al (2008)4 suggested that the shift from measuring sea surface temperatures using buckets to engine intake measurements caused part of the apparent hump in temperature in the early 1940s. Were it not for this hump, the period from 1910 to the early 1940s would not stand out so much as its own period of warming, requiring unique explanation. Patrick Michael: “So that means that probably about half, maybe half of that nine-tenths of the degree [of total warming] might be caused by greenhouse gases because when the planet warmed beginning in 1976“ Here, Michaels incorrectly attributes zero warming to CO2 until 1976 and then implicitly assumes that all other factors are held constant after that point. This is not the case. Careful analysis that attempts to take into account all major factors and their evolution in time indicates that anthropogenic increases in greenhouse gasses account for more than 100% of the observed warming on the century timescale (requiring cancellation from cooling influences). See the summary graphic from Carbon Brief, below. Source: Carbon Brief"
https://science.feedback.org/review/popular-article-in-the-independent-accurately-summarizes-june-heat-in-europe-conrad-duncan/,1.7,"The Independent, by Conrad Duncan, on 2019-07-02.",,"""June was hottest ever recorded on Earth, European satellite agency announces""",,,,,"This article in The Independent covers the release of June monthly average temperature data for Europe—which shows it was the warmest June on record by a significant margin—as well as an analysis of how climate change contributed to the extreme heat wave at the end of the month. The article was widely shared across social media, with over 325,000 engagements on Facebook and Twitter at the time of the review. Scientists who reviewed the article found that it accurately summarized this information, although it did not link to the primary sources. (However, a correction notice added shortly after publication notes that “A previous headline on this story suggested June was the hottest month ever recorded. Instead, it was the hottest June ever recorded. The headline and article have been amended to reflect this.“) Source: ECMWF, Copernicus Climate Change ServiceSee all the scientists’ annotations in context. You can also install the Hypothesis browser extension to read the scientists’ annotations in context.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: The article accurately and clearly states the facts regarding the recent extreme heat in June 2019 and its link to anthropogenic warming. This includes acknowledging that, at this point, this June record and its connection to climate change is based on only a single temperature product and one attribution study, and that further analysis may slightly change the initial conclusions drawn by researchers. Giorgio Vacchiano Assistant Professor, Università di Milano: Good data and clear explanation. Evidence about the June heatwave being 5 times more likely under climate change is missing. Victor Venema Scientist, University of Bonn, Germany: A decent summary of the European heat wave in June 2019. If anything the article understated how exceptional the weather was. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Annotations: The statements quoted below are from the article; comments are from the reviewers (and are lightly edited for clarity). Last month was the hottest June ever recorded, European satellite agency announces Victor Venema Scientist, University of Bonn, Germany: Copernicus Climate Services (managed by the European Centre for Medium-Range Weather Forecasts) also uses satellite data, but it is not a satellite agency, that would be ESA. I would suggest calling it a Climate Research or Climate Data Agency. The main source of this article is this press release by Copernicus Climate Services. The data showed European average ​temperatures were more than 2C above normal and temperatures were 6-10C above normal over most of France, Germany and northern Spain during the final days of the month, according to C3S. Victor Venema Scientist, University of Bonn, Germany: It is not a good idea to combine numbers for the full month and all of Europe with numbers for a few days and a part of Europe. That double difference makes it hard to understand and easy to miss one of the differences when casually reading it. 6-10 degrees Celsius for the entire month would have been special, but for a few days it is not. European average ​temperatures were more than 2C above normalVictor Venema Scientist, University of Bonn, Germany: European temperature this year in June were 2°C above the average over the period 1981 to 2010 (which was already warm due to man-made global warming). Climatologists call such averages over 30 year periods climate normals, a tradition that started before we knew about climate change. This technical term is probably best not used when writing for a general audience. The article understates how special the weather was by not mentioning that this average is 1°C above the previous record in 1999. And that it is about 1°C above the long-term warming trend, which is a rare outlier. Rapid assessment of average temperatures in France between 26-28 June showed a “substantial” increase in the likelihood of the heatwave happening as a result of human-caused global warming, experts at the World Weather Attribution group said. Victor Venema Scientist, University of Bonn, Germany: This part of the article is based on this press release by the World Weather Attribution group.1.5C in European temperature over the past 100 years Victor Venema Scientist, University of Bonn, Germany: That is also a reasonable estimate for the warming over land globally. (This is a global land warming estimate by Berkeley Earth; please take the values before 1900 with a pinch of salt.) Heatwaves occur in any climate, but we know that heatwaves are becoming much more likely due to climate change. Victor Venema Scientist, University of Bonn, Germany: That is right. See for example the IPCC Special Report on Extremes."
https://science.feedback.org/review/nasa-did-not-create-global-warming-by-manipulating-data-tony-heller-steven-goddard/,Inaccurate,"The New American, James Murphy, Tony Heller, 2019-06-26","[NASA] has been adjusting temperatures from the past[...] downward, while adjusting current-day temperatures upward, and those changes are responsible for most of the claimed global warming during that time.",,"Factually Inaccurate: Necessary adjustments to temperature datasets have, in total, reduced the apparent global warming trend since the late 1800s. Many independent datasets support the accuracy of NASA's temperature record.","Scientists at NASA—as well as other groups—constantly work to ensure that the data being used to estimate global average temperatures are as accurate as possible. As time goes on, updates can lead to small changes to estimates for previous years. These changes, however, are much too small to cause the warming trend that is clear in all available datasets.","[NASA] has been adjusting temperatures from the past—temperatures from as long ago as the mid-1800s—downward, while adjusting current-day temperatures upward, and those changes are responsible for most of the claimed global warming during that time.",,"Differences between versions of NASA’s global temperature dataset can easily be viewed on the NASA website. Source: NASA The most significant adjustments to data relate to changing ship-based instruments and methods used to measure sea surface temperatures around the time of World War II. As the use of thermometers in buckets of water hauled up on deck was replaced by thermometers in ship engine water intake pipes, the measured temperatures changed slightly, necessitating a correction to ensure an “apples-to-apples” comparison. Datasets operated by NOAA in the US, the UK Met Office, and others match and support NASA’s results. Upper panel: NOAA (red), NASA (blue), UK Met Office (green), and Berkeley Earth (yellow) datasets.Bottom panel: NOAA (red), NASA (green), and UK Met Office (blue) datasets.Source: US NCA Victor Venema Scientist, University of Bonn, Germany: [These comments were initially provided as part ofan article review.] To estimate how much the world has warmed, other changes need to be removed from the observations made at weather stations, observing ships and buoys. For example, if the surrounding of a station becomes more urban this often causes a warming that is local and needs to be removed to estimate the amount the world has truly warmed. Similarly when such a station moves to a better location, which is cooler, such a cooling jump needs to be removed for an accurate warming estimate. When it comes to the global mean temperature the main effect that needs to be removed is that in the past many sea surface temperature observations were made by hand with buckets and nowadays are made automatically at the water inlet of ships. While the water is hauled on deck and the thermometer adapts to the water temperature, the sea water evaporates and cools. Old measurements are thus 0°C to 0.4°C (0.7°F) too cold. Source: UK MetOffice In the unscientific formulation of [some], this means that the adjustments for this effect make the past warmer and the recent temperatures colder. But overall, the estimated global warming actually becomes smaller when taking into account all the adjustments—the opposite of [that claim]. [See figure in Mark Richardson’s comment below.] The adjustments climatologists make for land station data do make the warming greater. But the ocean adjustments (which reduce the warming trend) are more important for the global average. How large the adjustments need to be depends on how many other changes there were. The adjustments in the United States of America are relatively large, mainly due to two effects. In the past the thermometers were read more often in the afternoon, while nowadays they are read more often in the morning. The estimates of the daily average temperature based on minimum and maximum temperature thermometers are a bit colder in the morning than in the afternoon. A particularly cold morning can affect the observed minimum temperature of two days and a very hot afternoon the maximum temperature of two days. The temperature used to be measured with a thermometer in a Cotton Region Shelters in the USA. Nowadays they are mostly made using an Automatic Weather Station. These Automatic Weather Stations on average measure a lower temperature because they heat up less standing in the sun. The difference is especially large for the maximum temperature and for the summer. Comparing old summer maximum temperature with those of today would not be comparing like with like. And even if we had not invented the thermometer we would know it is warming: Glaciers are melting, from the tropical Kilimanjaro glaciers, to the ones in the Alps and Greenland. Arctic sea ice is shrinking. The growing season in the mid-latitudes has become weeks longer. Trees bud and blossom earlier. Wine grapes can be harvested earlier. Animals migrate earlier. The habitat of plants, animals and insects is shifting poleward and up the mountains. Lakes and rivers freeze later and break up the ice earlier. The oceans are rising. Mark Richardson Research Associate, Colorado State University/NASA JPL: [This comment was initially provided as part of a claim review.] Raw data show more global warming since 1880 than is reported by NOAA [or shown in other datasets]. This is because NOAA “adjusts” temperature data to fairly compare different measurement times, places, and technologies. The cooling effect of adjustments on global temperatures has been shown lots of times, such as with the graph below for 1880—2013 temperatures. A small group of conspiracy theorists flip this reality by “cherry picking”, which means using a fraction of the data to prop up claims that are false globally. It’s the sort of technique that would insist that this is a 100% blue cherry tree. NOAA scientists know that afternoons tend to be warmer than early mornings so it would be dumb to mix, for example, 1940s morning temperature readings with 2010s afternoon readings without accounting for this. They refuse to do obviously, provably dumb things so they carefully correct the data for a fair comparison. In the U.S., thermometers used to be read largely in the afternoon but now tend to be read in the morning1. This means that adjustments in the U.S. are warming, making it a popular choice for hints at conspiracy. There are ways to judge whether new claims are credible. Firstly, do they mention that global adjustments are cooling overall? Secondly, do they discuss reasons for adjustments including measurement time? If the answer is “no” to either then the author is hiding relevant information or is clueless about the topic and you should be very sceptical. Fortunately the scientific method can reliably test new claims through submissions to scientific journals for peer review, which tends to filter out obvious dumb mistakes like ignoring how afternoons are warmer than early mornings. Blog posts, think tanks and newspapers have no such filter. We know that NOAA’s adjustments improve things since they’re tested and updated whenever issues are found. For example, even a blogger who’s hostile to climate science results published a paper confirming that the NOAA U.S. average temperature changes are solid2. Another study by an independent “red team”, partly funded by a Koch foundation, supported NOAA’s conclusions3. I was involved with a check of NOAA’s ocean record using infrared scans from satellites4. The satellites supported NOAA’s results despite baseless & hysterical accusations that had been thrown at the scientists. After more than a decade of being relentlessly wrong, it’s time to be very careful with any new conspiracy claims aimed at the temperature records. 1-Vose et al (2003) An evaluation of the time of observation bias adjustment in the U.S. Historical Climatology Network, Geophysical Research Letters 2-Fall et al (2011) Analysis of the impacts of station exposure on the U.S. Historical Climatology Network temperatures and temperature trends, Journal of Geophysical Research: Atmospheres 3-Rohde et al (2012) A New Estimate of the Average Earth Surface Land Temperature Spanning 1753 to 2011, Geoinformatics & Geostatistics: An Overview 4-Hausfather et al (2017) Assessing recent warming using instrumentally homogeneous sea surface temperature records, Science Advances"
https://science.feedback.org/review/claim-that-electric-vehicles-cause-more-carbon-emissions-than-diesel-misrepresents-reality/,Inaccurate,"Infowars, Zero Hedge, Anonymous, 2019-04-22",New Study Confirms EVs Considerably Worse For Climate Than Diesel Cars,,"Misrepresents a complex reality: While some studies find that electric vehicles can be worse from a climate standpoint than the most efficient conventional (internal combustion engine) vehicles in areas where electricity comes mostly from coal, they generate less emissions than the average conventional vehicle. Electric vehicles become better for the climate as electricity generation becomes less carbon-intensive.","The general statement that electric vehicles result in greater CO2 emissions than diesel vehicles is not accurate, but there are specific situations where some diesel vehicles result in less emissions than some electric vehicles.",New Study Confirms EVs Considerably Worse For Climate Than Diesel Cars,,"Summary: Electric vehicles (EVs) are far from zero emissions, as both electricity generation and battery production are large sources of greenhouse gas. However, numerous studies show that EVs are responsible for considerably lower emissions over their lifetime than a typical conventional (internal combustion engine) vehicles across both the US and Europe. In countries with coal-intensive electricity generation, the benefits of EVs are smaller, and they have similar lifetime emissions to the most efficient conventional vehicles—such as hybrid-electric models. However, as countries decarbonize electricity generation to meet their climate targets, driving emissions will fall for existing EVs and manufacturing emissions will fall for new EVs. Comparisons between electric vehicles and conventional vehicles are complex, and depend on the size of the vehicles, the accuracy of the fuel economy estimates used, how electricity emissions are calculated, what driving patterns are assumed, and even the weather in regions where the vehicles are used. There is no single estimate that applies everywhere. Emissions from the production of electric vehicle batteries in Tesla’s gigafactory are likely considerably smaller than those assumed in the (not peer-reviewed) study cited by Zero Hedge, which relies on a review article primarily examining batteries produced in Asia. Source: Carbon Brief The figure below, from an analysis by the International Council for Clean Transportation (ICCT), shows an estimate of lifecycle emissions for a typical European conventional (internal combustion engine) car, the conventional car with the best available fuel economy (a Peugeot 208 1.6 BlueHDi), and a Nissan Leaf electric vehicle for various countries as well as the EU average. It includes tailpipe emissions (blue), emissions from the fuel cycle (red)—which includes oil production, transport, refining, and electricity generation—emissions from manufacturing the non-battery components of the vehicle (purple) and emissions from manufacturing the battery (green). Source: Hall and Lutsey (2018) Even in the countries with the greatest fuel cycle emissions, the overall lifecycle emissions of the Leaf are below the average car, and comparable to the most efficient conventional car. Other recent studies of electric cars in Germany have reached the opposite conclusion.One studyfound that emissions from EVs have emissions up to 43% lower than diesel vehicles.Anotherdetailed that “in all cases examined, electric cars have lower lifetime climate impacts than those with internal combustion engines”. For more information, see this article at Carbon Brief. Scientists’ Feedback: Jeremy J. Michalek Professor of mechanical engineering, Carnegie Mellon University: The general premise that EVs are not currently a panacea for climate change and that the life cycle greenhouse gas emissions from electric vehicles can be similar to or even greater than the most efficient gasoline or diesel vehicles is supported by other research, including the work of my group over the past decade. But it’s important to note that which technology comes out on top depends on a lot of things, especially: which specific vehicles are being compared, what electricity grid mix is assumed (especially whether or not the question is about the *change* in generation induced by new load, which is basically a mix of fossil fuels even in regions with wind, solar, hydro, and nuclear), what driving patterns are assumed, and even the weather See, for example, the maps in this study1, which examine these effects regionally. Whether electric beats gasoline/diesel depends heavily on which electric and gasoline/diesel vehicles are being compared and under what conditions. Here is our 2-page policy brief summarizing these issues. Source: Yuksel et al (2016) Studies that compare EVs (which are mostly smaller cars) to an average gasoline or diesel vehicle (much larger) and assign the average grid mix in an area to the electric vehicle tend to have favorable findings for EVs. Studies that compare EVs to comparable gasoline or diesel vehicles and examine the consequential emissions (how the grid will change in response to buying an EV vs. a gasoline/diesel vehicle) tend to have findings that are more mixed. I would put more weight on the second type of study and put more weight on peer-reviewed academic studies than on studies by advocacy groups or consulting groups that are not fully transparent. Emissions from battery manufacturing do not dominate life cycle emissions, but they are a not-insignificant portion of life cycle emissions. For vehicles with large battery packs, like Teslas, the emissions from battery manufacturing are a larger part of the picture and can tip the balance, relative to EVs with smaller batteries. We identified this some time ago in a study here[1]. There have been a variety of studies estimating emissions from battery production. The range used by the authors (145kg to 195kg CO2 per kWh of battery capacity) is within the range of estimates in the peer-reviewed scholarly literature, but it is higher than the most favorable studies that include battery recycling credits. [1] – Yuksel et al (2016) Effect of regional grid mix, driving patterns and climate on the comparative carbon footprint of gasoline and plug-in electric vehicles in the United States, Environmental Research Letters Volker Quaschning Professor, Hochschule für Technik und Wirtschaft HTW Berlin, Universit: The study has serious scientific errors. It always chooses the most favorable values for all the assumptions for the diesel, and always uses the worst-case values in the known bandwidth to calculate the impact of EV, and sometimes uses already refuted studies. In Germany, some articles have also appeared in major leading media, which deal very well with the mistakes."
https://science.feedback.org/review/financial-post-commentary-misrepresents-scientific-understanding-of-weather-extremes-ross-mckitrick/,-1,"Financial Post, by Ross McKitrick, on 2019-06-07.",,"""This scientist proved climate change isn’t causing extreme weather — so politicians attacked""",,,,,"This op-ed published by the Financial Post, written by Ross McKitrick, describes a presentation by University of Colorado Boulder researcher Roger Pielke, Jr. The article misrepresents analyses of trends in US weather extreme damages as indicators of global trends in the weather extremes, themselves. Researchers who reviewed the article explained that the US is not representative of the entire world. Trends in weather extremes are not always apparent from limited historical data, and can vary by region. Assessing observed trends is one piece of research on this topic, but an understanding of the physics of these weather events can also enable projections of future behavior that must also be considered. Overall, the evidence highlighted in the article—about certain types of extreme weather in some regions of the world—does not support its conclusion that “climate change isn’t causing extreme weather”. UPDATE (24 June 2019): The Financial Post article has been updated with an editor’s note that reads “This article has been updated from its original version to specifically identify the major extreme weather indicators that have been shown to have no solid connection to climate change.” The examples given make the article a little less accurate rather than more, but this minor change does not significantly affect the conclusions of our reviewers.See all the scientists’ annotations in context. You can also install the Hypothesis browser extension to read the scientists’ annotations in context.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Andreas Prein Project Scientist, National Center for Atmospheric Research: This article is misleading since it confuses changes in climate change impacts with changes in climate and weather extremes and it subjectively selects examples that support its message. There is clear scientific evidence that many weather and climate extreme events increase in intensity and frequency due to anthropogenic climate change. Munich Re, for example, publishes data on global major extreme events in its annual reports. Source: Munich Re While the number of geophysical extreme events (e.g. earthquakes, tsunamis, volcanoes) has stayed constant during the period 1980 to 2017, hydrologic extreme events and meteorological extremes increased significantly. The article is correct that increasing population and development is a primary contributor to increasing losses from extreme events. However, there is overwhelming evidence that climate change is increasing the frequency and intensity of, specifically heat, coastal flooding, and rainfall-related extreme events1. IPCC (2012) Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation Marlene Klockmann Postdoctoral research fellow, Helmholtz Zentrum Geesthacht: The arguments in this article are misleading for three reasons: (1) they mix the cost of the damage by extreme events with the actual physical phenomenon of the extreme event, (2) they only focus on data from the US, which is not representative of evidence in other regions, and (3) they completely ignore insights from climate projections, which are very clear on the link between global warming and an increase in extreme events. Ken Caldeira Senior Scientist, Carnegie Institution for Science: The central claim in the story is that “climate change was not leading to higher rates of weather-related damages worldwide, once you correct for increasing population and wealth.” Damage occurs when vulnerable infrastructure is exposed to bad weather, so the economic damage relates as much to the type of infrastructure as it does to the weather, so I will focus on the question of whether we have been seeing changes in extreme weather. The Earth has been getting hotter, so certainly in terms of global and annual averages, the global weather has been getting more extreme. Further, many more places have been experiencing more extreme heat than would be expected by chance alone, so it is fairly safe to say that human-induced climate change has in many places been causing an increase in the frequency of extremely hot weather. Storms are not like daily high temperatures, they occur sporadically and are difficult to forecast far in advance. That is, even if there were an increasing trend, it might not be possible to detect the climate signal through the randomness of weather. There is limited evidence supporting the idea that intense storms are becoming more frequent. Studies of individual storms using computer models, where the storm conditions are simulated as observed and then again with the cooler sea-surface temperatures that would have prevailed in the absence of fossil-fuel CO2 emissions, have concluded that warmer sea surface temperatures are leading to stronger storms. However, if this signal is real, it is hard to detect in century scale trends in weather statistics. While claims that extreme weather events are related to climate change in popular discourse often goes beyond the available data, we might want to be equally cautious in claiming that some extreme events are unrelated to climate change. (This climate.gov article gives some useful context.) Sometimes we have data like this: Source: Climate.gov Can we say that that 2015 precipitation was not a consequence of climate change because there is no significant preceding trend, or do we say that the 2015 event was likely caused by climate change because there was no historical precedent? Obviously, the case is not clear. There are many people who today tend to attribute such anomalous events to climate change, regardless of a lack of underlying mechanistic understanding. Uncertainty is not our friend. Uncertainty means that we are exposing ourselves to risk. My general rule of thumb is: “If some weather happens that has never happened before, there is a good chance that climate change has played a role.” This is not a scientific finding but an exhibition of my personal bias. Of course, others may have different priors. To get a broader perspective, people should be looking to the 2016 National Academy Report on Attribution of Extreme Weather Events in the Context of Climate Change to see what scientists really think, as reflected in a well-respected consensus process: The figure below (from that report) shows that confidence on attributing changes in extreme hot and cold events to climate change is fairly high, but that the confidence level goes down the less the event has to do with temperature and the more it has to do with the hydrological cycle—and “severe convective storms” is the type of extreme event listed that has the lowest level of understanding and lowest confidence in attribution to climate change. Conceptual diagram of the scientific understanding of the effect of climate change on different times of weather extremes.Source: National Academies of Science Another useful report is Chapter 18 of the 2015 IPCC AR5 Working Group II report, also the product of a highly respected consensus process. It should be noted that in the Technical Summary: to Chapter 18, there was no reference to increases in intense storms, and while there is evidence of increased storminess in some regions such a trend is not yet statistically significant at global scale. McKitrick does a service by calling attention to the relatively weak observation-based evidence for association of damage from extreme weather with climate change. Regardless of whether or not the reader finds compelling the evidence that climate change is increasing the number of intense storms, it is clear that climate change has been increasing the number of record hot days and heat spells. Thus the statements “Globally there’s no clear evidence of trends and patterns in extreme events” and “The bottom line is there’s no solid connection between climate change and the major indicators of extreme weather” would need to be regarded as false. We can be fairly sure that with continued greenhouse gas emissions, future weather will contain many days that are outside of today’s range of normal weather variability, so we know that the number of “extreme” weather days will increase. There are questions regarding the extent to which we can detect that increases in extremes are already happening and the extent to which we can project the amount of climate damage associated with increases in these extremes. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Annotations: The statements quoted below are from the article; comments are from the reviewers (and are lightly edited for clarity). This scientist proved climate change isn’t causing extreme weatherMarlene Klockmann Postdoctoral research fellow, Helmholtz Zentrum Geesthacht: This is misleading. The main argument of Pielke’s presentation at the University of Minnesota, the Hohenkammer Consensus Statement, and the IPCC reports is that the increasing COST due to extreme weather cannot be linked to climate change. Ryan Sriver Associate Professor, University of Illinois: The title is misleading. He didn’t prove anything. He’s simply claiming there are not yet definitive links between climate change and some extreme events. I would refer the readers to the most recent National Climate Assessment1 for a broader and longer list of salient impacts of climate change beyond the short and narrow selection quoted. 1 – US NCA (2018) Volume II: Impacts, Risks, and Adaptation in the United States Ken Caldeira Senior Scientist, Carnegie Institution for Science: The headline of this piece is incorrect. Nobody has “proved climate change isn’t causing extreme weather.” While just about everybody acknowledges that climate change is causing more record high temperatures and fewer record cold temperatures, the jury still is out on whether it can be said that climate change is causing other kinds of extreme weather, such as intense storms. There is a tendency by many to attribute every extreme event to climate change, and while that is not justified, in most cases of extreme weather there is insufficient data and understanding to make a clear determination of the extent to which climate change may or may not have played a role.While members of the media may nod along to such claims [about changes in weather extremes], the evidence paints a different story Marlene Klockmann Postdoctoral research fellow, Helmholtz Zentrum Geesthacht: This is again misleading. The evidence that is mentioned in this article is only one part of the complete picture. It focuses only on North America and only on the observational period. It neglects observational evidence from other regions in the world and the insights from climate projections. They concluded that trends toward rising climate damages were mainly due to increased population and economic activity in the path of storms, that it was not currently possible to determine the portion of damages attributable to greenhouse gases, and that they didn’t expect that situation to change in the near future. Marlene Klockmann Postdoctoral research fellow, Helmholtz Zentrum Geesthacht: This is true, but it is only one of 20 conclusions from the Hohenkammer Statement. Another conclusion, for example, is: “For future decades the IPCC (2001) expects increases in the occurrence and/or intensity of some extreme events as a result of anthropogenic climate change. Such increases will further increase losses in the absence of disaster reduction measures.” Globally there’s no clear evidence of trends and patterns in extreme events such as droughts, hurricanes and floods. Some regions experience more, some less and some no trend. Limitations of data and inconsistencies in patterns prevent confident claims about global trends one way or another. There’s no trend in U.S. hurricane landfall frequency or intensity. If anything, the past 50 years has been relatively quiet. There’s no trend in hurricane-related flooding in the U.S. Nor is there evidence of an increase in floods globally. Since 1965, more parts of the U.S. have seen a decrease in flooding than have seen an increase. And from 1940 to today, flood damage as a percentage of GDP has fallen to less than 0.05 per cent per year from about 0.2 per cent. Marlene Klockmann Postdoctoral research fellow, Helmholtz Zentrum Geesthacht: This is more or less a summary of the data cited in Pielke’s presentation and probably accurate. But as mentioned above, it does not give the whole picture. (1) The observational data for the US does not reflect changes in other regions. Heat waves in other regions can, for example, already be linked to climate change: “It is very likely that the number of cold days and nights has decreased and the number of warm days and nights has increased on the global scale. It is likely that the frequency of heat waves has increased in large parts of Europe, Asia and Australia. It is very likely that human influence has contributed to the observed global scale changes in the frequency and intensity of daily temperature extremes since the mid-20th century. It is likely that human influence has more than doubled the probability of occurrence of heat waves in some locations. (IPCC1) (2) The main argument for linking extreme weather with climate change comes from climate projections, which are completely omitted here. The IPCC special report on the 1.5 degree target2 is very clear in stating that a global warming of 2 degrees will lead to more extreme events than global warming of 1.5 degrees: “Climate models project robust differences in regional climate between present-day and global warming up to 1.5°C, and between 1.5°C and 2°C (high confidence), depending on the variable and region in question (high confidence). Large, robust and widespread differences are expected for temperature extremes (high confidence).” and “Limiting global warming to 1.5°C would limit risks of increases in heavy precipitation events on a global scale and in several regions compared to conditions at 2°C global warming (medium confidence). ” These are only summary statements, but detailed elaboration is given within the report. 1 – IPCC (2013) Climate Change 2013: The Physical Science Basis 2 – IPCC (2018) Global Warming of 1.5 °C Ryan Sriver Associate Professor, University of Illinois: Tropical cyclones are extreme and rare events thus statistically significant changes are difficult to detect especially given the limitations in historical observations before satellite coverage, but overall coastal flooding is becoming much more of a problem under global warming as sea levels rise. This will only get worse in the future. Some regions experience more, some less and some no trend. Limitations of data and inconsistencies in patterns prevent confident claims about global trends one way or another. Marlene Klockmann Postdoctoral research fellow, Helmholtz Zentrum Geesthacht: Confidence is often low due to the limited data availability. As also stated by the IPCC, low confidence does not necessarily imply that a link does not exist.There’s no trend in global droughts. Cold snaps in the U.S. are down but, unexpectedly, so are heatwaves. Marlene Klockmann Postdoctoral research fellow, Helmholtz Zentrum Geesthacht: Yes, but not in other regions of the world (see annotations above). Ryan Sriver Associate Professor, University of Illinois: The temperature claims are a bit misleading. We experience more and more record breaking warm temperatures over time due to global warming. These changes are damaging for many reasons beyond drought. The bottom line is there’s no solid connection between climate change and the major indicators of extreme weather Marlene Klockmann Postdoctoral research fellow, Helmholtz Zentrum Geesthacht: As stated in my comments above, this conclusion is not valid. It is based on incomplete reasoning. The argumentation in the article confuses the occurrence of events with their cost, neglects observational evidence from other regions than the US, and completely omits insight from climate projections. The fact that it is still difficult/impossible to attribute individual extreme events to climate change in the observational record makes it easy to say that the link between global warming and increasing extreme events does not exist. But projections are very clear, and the fact that we cannot detect the links in all observations YET does not mean that it will not emerge when the warming signal increases. See also e.g. Suarez-Gutierrez et al1 for a discussion of the role of internal natural variability in distinguishing between different warming regimes. 1 – Suarez-Gutierrez et al (2018) Internal variability in European summer temperatures at 1.5 °C and 2 °C of global warming, Environmental Research Letters"
https://science.feedback.org/review/iflscience-story-on-speculative-report-provides-little-scientific-context-james-felton/,-1.4,"IFLScience, by James Felton, on 2019-06-04.",,"""New Report Warns ""High Likelihood Of Human Civilization Coming To An End"" Within 30 Years""",,,,,"This article at IFLScience describes a report produced by an Australian think tank. The report attempts to describe a possible worst case climate scenario in 2050. The report claims this scenario leads to a “high likelihood of human civilization coming to an end”, but does not support this claim with evidence. Scientists who reviewed IFLScience’s story found that it failed to provide sufficient context for this report—differentiating, for example, between speculative claims and descriptions of peer-reviewed research. In particular, the story’s headline (“New Report Warns ‘High Likelihood Of Human Civilization Coming To An End’ Within 30 Years”) misrepresents the report as a likely projection rather than an exploration of an intrinsically unlikely worst case scenario.See all the scientists’ annotations in context. You can also install the Hypothesis browser extension to read the scientists’ annotations in context.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Amber Kerr Researcher, Agricultural Sustainability Institute, University of California, Davis: The content of the IFLScience article is mostly an accurate representation of the contents of the Breakthrough report, but the article tends to gloss over important caveats and probabilities that are given in the report. The least accurate part of the IFLScience article is the headline, which is an outright misrepresentation of the report. The article title states that there is, overall, a “high probability” of human civilization coming to an end in 30 years. This is extremely misleading. What the Breakthrough report actually says is that, in the most unlikely, “long-tail” biophysical scenario where climate feedbacks are much more severe than we expect, THEN there is a high likelihood of human civilization coming to an end. But the report authors explicitly state that this “high-end scenario” is beyond their capacity to model or to quantitatively estimate. Daniel Swain Climate Scientist, University of California, Los Angeles: The article uncritically reproduces claims from a recent report released by an Australian thinktank regarding the purported “end of human civilization” due to climate change over the next 30 years. While there is plenty of scientific evidence that climate change will pose increasingly existential threats to the most vulnerable individuals in society and to key global ecosystems, even these dire outcomes aren’t equivalent to the “annihilation of intelligent life,” as is claimed in the report. Andrew King Research fellow, University of Melbourne: The report this article is based on describes a scenario which is unlikely, but several aspects of what is included in the report are likely to worsen in coming decades, such as the occurrence of deadly heatwaves. The conclusion of a high likelihood that human civilisation will end is false, although there is a great deal of evidence that there will be many damaging consequences to continued global warming over the coming decades. Peter Kalmus Data Scientist, Jet Propulsion Laboratory: I don’t think it’s so easy to discount the essential warning of this report. However, it would have been stronger if the authors were more careful not to mention the unsupported concept of near-term human extinction, and the unsupported probabilistic claim that there is a “high likelihood” of their 2050 scenario which includes the collapse of civilization. I do not understand why non-scientist writers (neither report author is a scientist) feel a need to exaggerate sound scientific findings, when those findings are already quite alarming enough. I feel that humanity should undertake urgent climate action just as the report authors do, but I feel that misrepresenting the science is unhelpful and unnecessary. Richard Betts Professor, Met Office Hadley Centre & University of Exeter: This is a classic case of a media article over-stating the conclusions and significance of a non-peer reviewed report that itself had already overstated (and indeed misrepresented) peer-reviewed science – some of which was already somewhat controversial. It appears that there was not a thorough independent check of the credibility of the message. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Annotations: The statements quoted below are from the article; comments are from the reviewers (and are lightly edited for clarity). New Report Warns “High Likelihood Of Human Civilization Coming To An End” Within 30 Years Richard Betts Professor, Met Office Hadley Centre & University of Exeter: The headline overstates the conclusions of the report (which is already overdoing things). The reports says it presents a scenario, and under that scenario and all the assumptions within it, the report claims that there is a “high likelihood of human civilization coming to and end” – but even then, the report itself does not give the end of civilisation within 30 years. The process supposedly leading ultimately to collapse begins around 2050 but takes a long time to take effect. Also the processes themselves are not well-grounded in science, as they over-interpret published work. A new report has warned there’s an existential risk to humanity from the climate crisis within the coming decades, and a ‘high likelihood of human civilization coming to an end’ over the next three decades unless urgent action is taken. Andrew King Research fellow, University of Melbourne: This is hyperbole. The scenario constructed in this report does not have a “high likelihood” of occurring in part because it requires a confluence of circumstances coming together. While it’s certainly true that climate change will be damaging to society and the environment and many of the consequences will be severe this does not equate to a high likelihood of civilisation coming to an end. Richard Betts Professor, Met Office Hadley Centre & University of Exeter: The “report” is not a peer-reviewed scientific paper. It’s from some sort of “think tank” who can basically write what they like. The report itself misunderstands / misrepresents science, and does not provide traceable links to the science it is based on so it cannot easily be checked (although someone familiar with the literature can work it out, and hence see where the report’s conclusions are ramped-up from the original research). This requires us to work towards avoiding catastrophic possibilities rather than looking at probabilities, as learning from mistakes is not an option when it comes to existential risks. Andrew King Research fellow, University of Melbourne: The report focuses on possible scenarios very much on the extreme end of what could happen but then claims there’s a “high likelihood” of human civilisation ending. These two statements don’t fit together. With that in mind, they propose a plausible and terrifying “2050 scenario” whereby humanity could face irreversible collapse in just three decades. Peter Kalmus Data Scientist, Jet Propulsion Laboratory: Not to downplay the seriousness of what humanity is facing, but the report in fact doesn’t make this claim. While scientists do expect many of the changes to the Earth system due to global heating to be “irreversible,” and while this should be extremely concerning to any reasonable person, it is different than “irreversible human collapse” which, if you think about it, needs unpacking. Their analysis calculates the existential climate-related security risk to Earth through a scenario set 30 years into the future. Richard Betts Professor, Met Office Hadley Centre & University of Exeter: No, the report’s authors have merely read (or possibly seen without actually reading) a few of the scariest papers they could find, misunderstood (or not read properly) at least one of them, and presented unjustified statements. posing permanent large negative consequences to humanity that may never be undone, either annihilating intelligent life or permanently and drastically curtailing its potential. Daniel Swain Climate Scientist, University of California, Los Angeles: As I climate scientist, I am unaware of any scientific research that suggests changes in Earth’s climate capable of “annihilating intelligent life” over the next 30 years. There is plenty of evidence that climate change will pose increasingly existential threats to the most vulnerable individuals in society; to low-lying coastal cities and island nations; to indigenous cultures and ways of life; and to numerous plant and animal species, and perhaps even entire ecosystems. Such consequences are well-supported by the existing evidence, are already starting to emerge in certain regions, and should be of paramount concern. But even these very dire outcomes aren’t equivalent to the “end of human civilization,” as is claimed in the report. Peter Kalmus Data Scientist, Jet Propulsion Laboratory: There is no scientific basis to suggest that climate breakdown will “annihilate intelligent life” (by which I assume the report authors mean human extinction) by 2050. However, climate breakdown does pose a grave threat to civilization as we know it, and the potential for mass suffering on a scale perhaps never before encountered by humankind. This should be enough reason for action without any need for exaggeration or misrepresentation! A “Hothouse Earth” scenario plays out that sees Earth’s temperatures doomed to rise by a further 1°C (1.8°F) even if we stopped emissions immediately. Peter Kalmus Data Scientist, Jet Propulsion Laboratory: This word choice perhaps reveals a bias on the part of the author of the article. A temperature can’t be doomed. And while I certainly do not encourage false optimism, assuming that humanity is doomed is lazy and counterproductive. Fifty-five percent of the global population are subject to more than 20 days a year of lethal heat conditions beyond that which humans can survive Richard Betts Professor, Met Office Hadley Centre & University of Exeter: This is clearly from Mora et al (2017) although the report does not include a citation of the paper as the source of that statement. The way it is written here (and in the report) is misleading because it gives the impression that everyone dies in those conditions. That is not actually how Mora et al define “deadly heat” – they merely looked for heatwaves when somebody died (not everybody) and then used that as the definition of a “deadly” heatwave. North America suffers extreme weather events including wildfires, drought, and heatwaves. Monsoons in China fail, the great rivers of Asia virtually dry up, and rainfall in central America falls by half. Andrew King Research fellow, University of Melbourne: Projections of extreme events such as these are very difficult to make and vary greatly between different climate models. Deadly heat conditions across West Africa persist for over 100 days a year Peter Kalmus Data Scientist, Jet Propulsion Laboratory: The deadly heat projections (this, and the one from the previous paragraph) come from Mora et al (2017)1. It should be clarified that “deadly heat” here means heat and humidity beyond a two-dimension threshold where at least one person in the region subject to that heat and humidity dies (i.e., not everyone instantly dies). That said, in my opinion, the projections in Mora et al are conservative and the methods of Mora et al are sound. I did not check the claims in this report against Mora et al but I have no reason to think they are in error. 1- Mora et al (2017) Global risk of deadly heat, Nature Climate Change The knock-on consequences affect national security, as the scale of the challenges involved, such as pandemic disease outbreaks, are overwhelming. Armed conflicts over resources may become a reality, and have the potential to escalate into nuclear war. In the worst case scenario, a scale of destruction the authors say is beyond their capacity to model, there is a ‘high likelihood of human civilization coming to an end’. Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: This is a highly questionable conclusion. The reference provided in the report is for the “Global Catastrophic Risks 2018” report from the “Global Challenges Foundation” and not peer-reviewed literature. (It is worth noting that this latter report also provides no peer-reviewed evidence to support this claim). Furthermore, if it is apparently beyond our capability to model these impacts, how can they assign a ‘high likelihood’ to this outcome? While it is true that warming of this magnitude would be catastrophic, making claims such as this without evidence serves only to undermine the trust the public will have in the science. Daniel Swain Climate Scientist, University of California, Los Angeles: It seems that the eye-catching headline-level claims in the report stem almost entirely from these knock-on effects, which the authors themselves admit are “beyond their capacity to model.” Thus, from a scientific perspective, the purported “high likelihood of civilization coming to an end by 2050” is essentially personal speculation on the part of the report’s authors, rather than a clear conclusion drawn from rigorous assessment of the available evidence. Richard Betts Professor, Met Office Hadley Centre & University of Exeter: So there is only a “high likelihood” in the scenario that the report’s authors have constructed here. They do not say that their scenario itself is “highly likely” (in fact they say it is a “sketch”) – so the headline of this article is not justified. The most recent IPCC report lays out a future if we limit global heating to 1.5°C instead of the Paris Agreement’s 2°C. Peter Kalmus Data Scientist, Jet Propulsion Laboratory: The article doesn’t mention it, but it’s worth pointing out that the underlying report criticizes the IPCC for being too “reticent” and gives an erroneous example: it claims that mean global temperatures will accelerate beyond the IPCC’s projections since human greenhouse gas emissions are themselves accelerating. Emissions ARE accelerating exponentially, leading to exponential CO2 atmospheric fraction increase, but exponential growth in CO2 fraction leads to linearly increasing global mean temperature. By 2050 there’s a scientific consensus that we reached the tipping point for ice sheets in Greenland and the West Antarctic well before 2°C (3.6°F) of warming Richard Betts Professor, Met Office Hadley Centre & University of Exeter: This is somewhat unclear phrasing from the report. Although studies have shown it is possible that the threshold for the Greenland Ice Sheet tipping point may be lower than 2C global warming (relative to pre-industrial), there is not currently a scientific consensus that this is where the threshold is. It seems to authors’ scenario is that scientists living in 2050 have reached the consensus that the tipping point has been passed by that time, but that’s different – again it’s part of the scenario and does not support the “end of civilisation by 2050” headline."
https://science.feedback.org/review/the-australian-commentary-by-ian-plimer-relies-on-false-claims-to-make-its-case/,-2,"The Australian, by Ian Plimer, on 2019-05-16.",,"""The truth of climate change is revealed at school""",,,,,"This commentary by Ian Plimer, published by The Australian, criticizes a political leader’s stance on climate change, but makes a number of verifiably false claims about climate science and energy systems as the foundation of that argument. Scientists who reviewed the article found that it repeated common false claims about climate science, stating that human greenhouse gas emissions are trivial and not responsible for current climate change, for example. These claims are contradicted by the available evidence and decades of published scientific research.You can read the article here. You can also install the Hypothesis browser extension to read the scientists’ annotations in context. REVIEWERS’ OVERALL FEEDBACK: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Katrin Meissner Professor, University of New South Wales: This article is misleading, derogatory, and teeming with false statements. The arguments in this article have been put forward by climate deniers before, and they all have been proven wrong by scientists. There is nothing new; déjà vu effect. Victor Venema Scientist, University of Bonn, Germany: This op-ed by Ian Plimer in The Australian is exceptional. I see no way to honestly summarize how bad it is without sounding unprofessional. Mark Richardson Research Associate, Colorado State University/NASA JPL: This article mixes falsehoods and logical errors. For example, the evidence is overwhelming that most recent warming is human caused, and that solar panels and wind turbines generate multiple times more power than was used in their construction: this article says the opposite to both of these facts. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Annotations: The statements quoted below are from the article; comments are from the reviewers (and are lightly edited for clarity). […] the Roman Warming, the Dark Ages, the Medieval Warming and the Little Ice Age. These took place before industrialisation and were all driven by changes in the sun. Katrin Meissner Professor, University of New South Wales: These climate fluctuations were small, regional and at a much smaller scale than what the planet experiences today. None of them were globally as warm as today. They were also driven by other forcings than greenhouse gases. The author is confused between small-scale natural variability and long-term irreversible large-scale change. Climate Feedback: To learn more about the little ice age, read our review of one of the many articles wrongly predicting an imminent cooling. Professor Michael Lockwood explains: “The term “mini ice age” is inherently misleading in the context of solar variations as it implies a global decrease in temperatures and at all times of year. This does not apply at all to the solar Maunder minimum. Temperature observations from central England show that summers during the Maunder minimum were, if anything, slightly warmer than average[…] there was increased occurrence of cold winters during the Maunder minimum but this is an effect of jet stream behaviour specific to northern Europe and the USA and not a global ice age.”natural warm times, like now, bring great prosperity, increased longevity and less disease, whereas Jack Frost brings death, depopulation and economic stresses. Katrin Meissner Professor, University of New South Wales: This is a common misconception. We are not talking about minor climate fluctuations, we are experiencing a major, abrupt climate change. Because current climate change is so fast, ecosystems are at risk, infrastructure is at risk, and the result will certainly not bring great prosperity. Climate change related health impacts are also on the rise, so there will certainly not be “less disease” Like countless other organ­isms, we move and adapt when the environment changes. Species thrive when it is warm. Katrin Meissner Professor, University of New South Wales: The rate of change is important. CO2 concentrations and temperatures are changing at an unprecedented rate, which will make it impossible for many organisms to “move and adapt”. carbon dioxide is the food of life and without this natural gas, which occurs in space and all planets, there would be no life. Victor Venema Scientist, University of Bonn, Germany: The same goes for water, it is natural and necessary for life, you can still drown in a flood. Too much and too little carbon dioxide and water is bad for you. The proposal is to stop messing with our climate system by changing the CO2 from the level it had when human civilization was built. when 3 per cent of total annual global emissions of carbon dioxide are from humans and Australia prod­uces 1.3 per cent of this 3 per cent, then no amount of emissions reductio­n here will have any effect on global climate. Martin Singh Postdoctoral Research fellow, Harvard University: This is enormously misleading; humans are entirely responsible for the rapid increase in the greenhouse gas concentrations within the atmosphere over the last 150 years, primarily through the burning of fossil fuels. Katrin Meissner Professor, University of New South Wales: The natural emissions are balanced by natural sinks (comparable to our bank accounts, salary comes in, rent or mortgage goes out, grocery bills go out, the incoming and outgoing fluxes are high, but at the end of the month we end up with more or less the same amount of money we started with). Human emissions are on top of this fine natural balance. Humans add CO2 but they don’t remove CO2. And while this would be great news for our bank accounts, it’s not great news for our planet. Victor Venema Scientist, University of Bonn, Germany: Human CO2 emissions are two times larger than the increase of the CO2 concentration in the atmosphere. The oceans and vegetation fortunately have taken up the other half1-2. Humans are fully responsible for the atmospheric CO2 increase. We can only fight climate change if everyone does their part. Australia doing more makes other countries willing to do more. 1 – Le Quéré et al (2018) Global Carbon Budget 2018. Earth Systems Science Data. 2- IPCC (2013) Section 6.3.1 Carbon Dioxide Emissions and Their Fate Since 1750 Climate Feedback: One reason we know that the increase in atmospheric CO2 concentrations is the result of human activities is because the carbon from fossil fuels has a different isotopic composition. Learn more in this article. whenever in the past there was an explosion of plant life, the carbon dioxide content was far higher than at present. Mark Richardson Research Associate, Colorado State University/NASA JPL: The last time carbon dioxide levels were as high as we’re on course for, sea levels were 25-40 metres higher1. The homes of billions of people would be under this sea level. This is projected to take a long time, but even with relatively low emissions we expect tens to hundreds of millions of people’s homes to be flood risks due to rising seas this century. And annual flooding costs of trillions of dollars without heavy investment in flood defences or abandoning cities2. If you think that potentially causing hundreds of millions of refugees and trillions of dollars in damages is fine because some plants did well in the same conditions millions of years ago when humans weren’t around, then you could support this article. 1- Tripati et al (2009) Coupling of CO2 and Ice Sheet Stability Over Major Climate Transitions of the Last 20 Million Years, Science 2- Jevrejeva et al (2018) Flood damage costs under the sea level rise with warming of 1.5 °C and 2 °C, Environmental Research LettersIf we halve the carbon dioxide content of the atmosphere, all life dies. Katrin Meissner Professor, University of New South Wales: If we halve the present day carbon dioxide content in the atmosphere, we will end up with the most common CO2 concentrations over the past 2 million years… those during an ice age. Life did not die. All the species we know today (including hominins) actually lived through several cycles of ice ages. for thousands of millions of years the Earth has been changing, with cycles­ and one-off events such as an asteroid impact, super-volcano or a supernova explosion. Katrin Meissner Professor, University of New South Wales: That is true. And there were several mass extinctions associated with these events. As far as we can go back in time based on our geological climate proxies, past natural climate change has very likely been much slower (at least by a factor 10) than what we experience today. It has yet to be demonstrated that the climate change today is any different from those of the past. Katrin Meissner Professor, University of New South Wales: This has been demonstrated. See, for example, recent IPCC reports. Victor Venema Scientist, University of Bonn, Germany: Trivially wrong. This time climate change is due to human CO2 emissions. That has not happened before. Source it still has not been shown that human emissions of carbon dioxide drive ­global warming.Katrin Meissner Professor, University of New South Wales: This statement is wrong. CO2 is a greenhouse gas and human emissions are increasing its concentration. Human emissions therefore drive global warming1. This can be measured, it can be explained theoretically and it can be seen in the past evolution of temperatures and CO2. 1- Stips et al (2016) On the causal structure between CO2 and global temperature, Scientific Reports Martin Singh Postdoctoral Research fellow, Harvard University: There is a mountain of evidence for the importance of carbon dioxide for Earth’s climate. We have known for over 100 years that CO2 is a greenhouse gas; without CO2 in the atmosphere, Earth’s surface would be tens of degrees colder, and probably not habitable for life. Increasing the CO2 concentration enhances the greenhouse effect, warming the Earth’s surface; this enhancement of the greenhouse effect has been observed by satellites. Furthermore, differences in the concentration of CO2 are known to be important for climate change that has occurred in Earth’s distant past, from hundreds of thousands to millions of years ago. Victor Venema Scientist, University of Bonn, Germany: This is so trivially wrong and such old well-established science, that I hope a Wikipedia link is allowed. Climate Feedback: For a beginner’s guide, read this article by NASA. [subsidies for wind and solar] add to emissions because coal-fired elec­tricity needs to be on standby for when there is no wind or sunshine. Mark Richardson Research Associate, Colorado State University/NASA JPL: Baseless and, in regions where this has been studied, false. For example, in Illinois1. And this ignores more efficient ways of reducing backup emissions, such as energy storage like batteries. 1- Valentino et al (2012) System-Wide Emissions Implications of Increased Wind Power Penetration, Environmental Science & Technology The amount of energy used to construct solar and wind facilities is greater than they produce in their working lives. Mark Richardson Research Associate, Colorado State University/NASA JPL: This is false. The average working wind farm that has been studied produces about 20 times more energy than was used to make them1. Some wind farms are better, some are worse. Solar, too, produces more energy than was used to make the solar farm. 1- Kubiszewski et al (2010) Meta-analysis of net energy return for wind power systems, Renewable Energy Ken Caldeira Senior Scientist, Carnegie Institution for Science: Numbers for “Energy Return on Investment” (EROI) are all over the place, but a nice summary with references to supporting information was produced for Scientific American by Mason Inman for the April 2013 edition of Scientific American. Mason estimated that wind returns about 20 times the energy input and solar around 6 times their energy input. While these numbers do depend on a range of assumptions, the idea that these ratios are less than one is wrong and not defensible. The construction of wind turbines and solar panels does result in some carbon dioxide emission but far less than would be emitted were that electricity generated using fossil fuels such as coal, gas, or oil. Therefore, if the alternative is fossil fuels, these technologies help avoid carbon dioxide emissions. It should be noted that Energy Return on Investment is likely to increase over time as the economy becomes more efficient and thus economic inputs to the production of energy technologies becomes less energy intensive. Mark Diesendorf, Honorary AssociateProfessor, University of New South Wales:: The energy input to a wind farm is generated in 3 to 6 months of its operation, depending on location, and the energy input to a solar farm is generated in 1 to 3 years of its operation, depending on location and type of solar panel used. Both wind and solar farms have expected lifetimes of about 25 years. Lunardi et al (2018) Life cycle assessment on PERC solar modules, Solar Energy Materials and Solar Cells Martínez et al (2009) Life cycle assessment of a multi-megawatt wind turbine, Renewable Energy Raugei (2012) The energy return on energy investment (EROI) of photovoltaics: Methodology and comparisons with fossil fuel life cycles, Energy Policy “As soon as renewables were introduced into the grid, electric­ity prices increased and delivery became unreliable. Increased elec­tric­ity costs have created unemployment, and many pensioners and the poor cannot afford electricity. An increase in renewables will make matters worse.” Ken Caldeira Senior Scientist, Carnegie Institution for Science: Today, variable renewable energy sources do present challenges to electricity grid management and do result in price volatility. If reliable electricity is the goal, given the high cost of electricity storage and the lack of continental scale electricity grids, deep penetration of intermittent renewables does increase system costs, narrowly defined. However, it is important to bear in mind that fossil fuels impose a huge cost on the environment that is not monetized and reflected in electricity prices to the consumer. If the full cost, including environmental costs, of fossil fuel energy were passed on to the consumer, on most analyses expanded renewable energy would be a net cost saver. Fossil fuels have been getting a free ride by imposing costs to current and future generations around the world. Different jurisdictions adjust electricity costs in different ways. The Australian market, like the market in Texas, is notable for market structures with high price volatility. Other markets put more emphasis on maintaining capacity to deal with spikes in demand or crevasses in renewable energy generation. This tends to spread costs out over time and allow businesses to better plan the electricity costs, but there is an added cost to building the extra generation capacity. There is no free lunch. Low cost of fossil fuel electricity generation comes at the cost of imposing climate change throughout the world and for many generations to come. Avoiding imposing these costs on others means imposing a little more cost on people using electricity. The goal of clean energy research and development is to make this “little more cost” as little as possible, and perhaps even eliminate the cost differential entirely. Renew­ables such as wind turbines are environmentally disastrous because they pollute a huge land area, slice and dice birds and bats, kill insects that are bird food, create health problems for humans who live within kilometres of them, leave toxins around the turbine site and despoil the landscape. Mark Richardson Research Associate, Colorado State University/NASA JPL: There is no comparison here with the alternatives. For example, the claimed wind turbine health damages, for which the author shows evidence of zero deaths, should be compared with the millions of deaths that the World Health Organisation links to pollution every year, much of which is from fossil fuels."
https://science.feedback.org/review/its-true-that-the-current-carbon-dioxide-level-is-higher-than-any-time-in-human-existence/,Accurate,"NBC News, Denise Chow, 2019-05-14",the concentration of carbon dioxide in Earth’s atmosphere has climbed to a level last seen more than 3 million years ago — before humans even appeared on the rocky ball we call home,,"Accurate: It is possible that the concentration of atmospheric CO2 was this high a little less than 3 million years ago, but it is certainly true that this was before the appearance of humans.","The concentration of carbon dioxide in the atmosphere is increasing several parts per million each year, and has already reached levels not seen since much warmer climates in the geologic past.",the concentration of carbon dioxide in Earth’s atmosphere has climbed to a level last seen more than 3 million years ago — before humans even appeared on the rocky ball we call home,,"Scott Wing Curator and Research Scientist, Department of Paleobiology, Smithsonian Institution: This NBC piece is good and the quotes are apropos and accurate. I wouldn’t want to detract from the good reporting and good comments in the story from Ralph, Rob, Dana, and Gavin, but there are two points that could be added if there were a venue for more information: 1. Estimates for CO2 in pre-ice-core time (>~0.8 Ma) are much less certain. So 415 might be as high as the Earth has been in the last 3 million years, but it’s not out of the range of estimates that hasn’t been this high in 15-18 million years. Even for the warm middle-late Eocene (34-56 million years ago) there are CO2 estimates as low as 400-500 ppm (though also many more near 1000 ppm). So it is possible that today’s levels (and especially those of the next few decades) might be unprecedented in the last 45-50 Ma. As with so much news about climate, we try to be “reasonable” from the start, but the upper bounds of our estimates don’t exclude much more extreme scenarios. The eventual equilibrium climate with 500 ppm of CO2 could mean no polar ice and hundreds of feet of sea level rise, whereas it seems extremely unlikely it would be cooler than we think. 2. Rob’s statement is good: “We’re not going to see the full consequences of 415 parts per million of carbon dioxide today,” Jackson said. “It’ll take a thousand years of people — 30 generations of people — to pay the price of what we’re doing today.” There is the possible implication that our descendants will pay the price of losing most coastal infrastructure, much arable land, etc. Another way our descendants could pay is quite literally to pay for the removal of CO2 from the atmosphere in hopes of avoiding the worst long-term consequences for sea-level rise and other things.Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: I can confirm that this statement is accurate. Firstly, the relatively easy bit: modern humans (Homo sapiens) are thought to have diverged some 350,000 years ago. Even the earliest members of the genus Homo, which was a very different species with nothing like the brain capacity of modern humans, first appeared around 1.8 million years ago by most estimates. So yes, it was before we arrived. So what do we know about CO2 over this time period? Below is a figure1 taking CO2 from ~2.4-3.2 million years ago (goes back in time from left to right). Panel a shows some old estimates generated from carbon isotopes in alkenones (fossil biomarkers produced by marine algae), which we now know have some problems, and don’t always record CO2 as well as other proxies2. In panel b are some old boron isotope data, since when isotope measurement techniques have been improving, and our understanding of the proxy has improved—some data shown in red squares was recently recalculated3. Data from the most up-to-date techniques of boron isotope measurement are shown in panel c (raw data) and panel d (what that translates to in pCO2—white circle is excluded as an outlier). You can see that the margins of uncertainty in data (68% confidence in dark blue shading, 95% confidence in lighter blue), and some data points from one of the sites marked in red circles, do at times cross over the 415 ppm value. So strictly speaking we can’t rule out the possibility that at some point within the period from 2-3 million years ago, CO2 very briefly reached levels slightly above 415 ppm. However, certainly the average CO2 (averaging out natural orbital variability) marked by the thick blue line in panel d, never gets above 415 ppm CO2 over this interval. Source: Martínez-Botí et al (2015) A useful resource for this information is the Palaeo-CO2 Project website, where workers in the field have vetted which datasets should no longer be trusted due to doubts about the proxies/datasets thrown up by later research, and which records can be considered amongst the more reliable estimates. Here you can see (figure last updated maybe two years ago?) that pCO2 didn’t regularly get above 400 ppm until before ~3 Ma (or million years ago). 1- Martínez-Botí et al (2015) Plio-Pleistocene climate sensitivity evaluated using high-resolution CO2 records, Nature 2- Badger et al (2019) Insensitivity of alkenone carbon isotopes to atmospheric CO2 at low to moderate CO2 levels, Climate of the Past 3- Dyez et al (2018) Early Pleistocene Obliquity‐Scale pCO2 Variability at ~1.5 Million Years Ago, Paleoceanography and PaleoclimatologyMarcus Badger Lecturer in Earth Sciences, The Open University: The article is broadly correct, in that atmospheric CO2 has not been as high as 415 ppm for millions of years. However, there is some uncertainty as to exactly when CO2 was last 415 ppm. We have several ways of getting at a value for atmospheric CO2 in the time before heroic humans like Ralph Keeling were measuring it. Probably the most robust is the record from the ice cores. When snow falls and turns to ice, it traps tiny bubbles of the atmosphere at the time it fell within the ice. By drilling long ice cores in Antarctica and Greenland we can melt the ice, retrieve that atmospheric sample and measure the CO2 concentration from when the ice formed. However we currently only(!) have a good ice core record up to 800 thousand years ago1. Some older ice has been recovered but its age is uncertain (around 1 million years2). None of the ice core record exceeds modern day values of atmospheric CO2, and most of it is well below 300 ppm. Beyond the ice cores, we have to rely on “proxy” measurements–geochemical signals from which we can calculate CO2. Two of these, the carbon isotopic composition of marine algae, and the boron isotopic composition of marine foraminifera fossils, have been deployed for the past few millions of years. These records overlap with and go beyond the ice cores, and although the record for the past few million years is currently incomplete, the last time it looks likely that CO2 exceeded today’s 415 ppm was over two million years ago3, 4 . If we look at these records at face value (and ignore uncertainties, which we shouldn’t) then the most recent datapoint in those records above 415 is 2.4 million years ago3 which just sneaks into the Pleistocene, rather than the Pliocene. But if we are a little more careful with our data, it’s true to say the last time we are confident CO2 exceeded 415 then it’s the Pliocene for sure, and closer to 3 million years ago. As the article says, this is well before modern humans evolved, and was a much warmer time, with global mean temperatures 2-3 degrees Celsius higher than pre-industrial and much higher sea levels—certainly a climate we should look to avoid. Figure – Plio-Pleistocene CO2 from ice core (red) and boron isotopes (blue) from 3.5 million years ago to present on the left and over the past 1,000 years on the right. Source: Gavin Foster 1 – Bereiter et al (2014) Revision of the EPICA Dome C CO2 record from 800 to 600 kyr before present, Geophysical Research Letters 2 – Higgins et al (2015) Atmospheric composition 1 million years ago from blue ice in the Allan Hills, Antarctica, PNAS 3 Martínez-Botí et al (2015) Plio-Pleistocene climate sensitivity evaluated using high-resolution CO2 records, Nature 4 – Bartoli (2011) Atmospheric CO2 decline during the Pliocene intensification of Northern Hemisphere glaciations, PaleoceanographyLee Kump Professor, PennState University: The direct measurement of ancient atmospheric composition is restricted to bubbles in continental ice sheets (Greenland and Antarctica), and that record only extends back about 1 million years. Clearly, the 415 ppm level today greatly exceeds the maximum records in this time period (which topped out during interglacial times at less than 300 ppm). For more ancient times we have to use proxy measures, that is, measurements of other things like the density of pores (stomata) on fossil leaves (calibrated with greenhouse data) or the boron content of fossil shells (sensitive to the CO2 content of the surface ocean, which is tightly linked to the atmosphere). Those proxies give somewhat different results as we go further back in time, but none indicate levels above 415 ppm before about 2.6 million years ago, and only one measurement I know of shows this; the next cluster is at around 3 million years (see, for example, Wang et al, 2015). Other proxy records indicate that CO2 levels above 415 ppm didn’t occur for the last few tens of millions of years. Wang et al (2015) Evolutionary History of Atmospheric CO2 during the Late Cenozoic from Fossilized Metasequoia Needles, PLoS One"
https://science.feedback.org/review/video-falsely-claiming-to-be-barron-trump-also-falsely-claims-humans-arent-causing-climate-change/,Flawed reasoning,"""Ivanka_Trump"" Facebook account, Dan Peña, 2019-05-04",Fifty-five thousand years ago the whole world was 2°C warmer than it is today[...] It's all cyclical; [human-caused greenhouse gas emissions are] not a fart in the wind. Sea level rise is not going to happen.,,"Factually Inaccurate: The speaker likely means to refer to a climate period known as the Eemian, but this was about 125,000 years ago, not 55,000 years ago. The slow-changing cycles of Earth's orbit were in a different configuration then, leading to warmer temperatures. Flawed Reasoning: The existence of past climate changes does not indicate humans cannot change climate today any more than the existence of natural fires in the past would indicate arson is impossible today.","The claim that natural climate changes in Earth's past indicate that humans today aren't changing the climate is based on fallacious reasoning. Similarly, the argument that sea levels are not going to rise since coastal investors don’t yet take it into account is also flawed.",Fifty-five thousand years ago the whole world was 2 degrees C warmer than it is today[...] It's all cyclical; [human-caused greenhouse gas emissions are] not a fart in the wind. Sea level rise is not going to happen.,,"The idea that the existence of a warm climate in the past proves humans aren’t responsible for modern warming is simply a logical fallacy. There are several climate forcings (factors that can alter Earth’s average temperature), including the sunlight reaching the Earth, the greenhouse gases that retain heat energy leaving the Earth, and even volcanic eruptions. Before human civilization, Earth’s climate changed for a number of reasons. The pattern of “ice ages” over the past several million years, for example, was driven by cycles in Earth’s orbit that alter the strength of sunlight reaching different parts of the planet over many thousands of years. Plate tectonics has also altered the climate over time by influencing the number of volcanic eruptions (releasing carbon dioxide into the atmosphere) and the amount of weathering bedrock (removing carbon dioxide from the atmosphere)*. No matter the source, an increase or decrease in greenhouse gases will alter Earth’s temperature. Currently, the concentrations of carbon dioxide and other greenhouse gases are increasing because of human-caused emissions, not something like volcanic eruptions. And no matter the cause of increasing carbon dioxide, it results in a stronger greenhouse effect and warmer temperatures. The 2017 US National Climate Assessment summarized the science on the cause of climate change this way: “This assessment concludes, based on extensive evidence, that it is extremely likely that human activities, especially emissions of greenhouse gases, are the dominant cause of the observed warming since the mid-20th century. For the warming over the last century, there is no convincing alternative explanation supported by the extent of the observational evidence.” Macdonald et al (2019)Arc-continent collisions in the tropics set Earth’s climate state, Science Advances Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: [This comment comes from an evaluation of a similar claim.] We are well aware that there are climatic fluctuations through geological time. Huge numbers of scientists study how the Earth’s climate has fluctuated before, and we know what caused those changes. Current warming is not related to any natural climate cycle, or process, or astronomic phenomenon. Mark Richardson Research Associate, Colorado State University/NASA JPL: [This comment comes from an evaluation of a similar claim.] Here are logically identical arguments: “England scored goals before Harry Kane, so Harry Kane can’t score goals” Or in American English: “The New England Patriots scored touchdowns before Rob Gronkowski, so Rob Gronkowski can’t score touchdowns”. Or more simply: “Fires happened before humans, so humans can’t cause fires”.So if you agree with this logic and that humans aren’t causing CO2 to rise, you also have to believe that Harry Kane and Rob Gronkowski never scored anything and could never score anything, and that no fire has been caused by a human ever.Human-caused global warming, goals by Harry Kane, touchdowns by Rob Gronkowski, and fires set by people are all in the same boat. We have enormous evidence that they exist. Richard Betts Professor, Met Office Hadley Centre & University of Exeter: [This comment comes from an evaluation of a similar claim.] The Earth’s climate has always varied, even before humans began to influence it. Climate scientists have always been very clear about this. But human-caused emissions of CO2 and other greenhouse gases have now added a new cause of climate change in addition to the existing causes of natural climate variability. Dan Peña’s claim that sea levels are not going to rise since coastal investors don’t yet take it into account is also flawed. Observations should be taken into account to inform one’s conclusions, and observations from tide gauges and satellites show that sea levels are rising globally, as seen in the figure below. Daniel Swain Climate Scientist, University of California, Los Angeles: A wide range of direct measurements (i.e. tidal gauges) and indirect measurements (i.e., gravity monitoring satellites) show that the rate of sea level rise has increased (i.e., accelerated) in recent years. Dieng et al (2017) New estimate of the current rate of sea level rise from a sea level budget approach, Geophysical Research Letters [the article concludes: “An important increase of the global mean sea-level rate is found during the second half of the altimetry era (2004–2015) compared to the 1993–2004 time span, mostly due to Greenland mass loss increase and also to slight increase of all other components of the budget.”] Peter deMenocal Professor, Lamont-Doherty Earth Observatory, Columbia University, and Director, Center for Climate and Life: The best available data show that the rate of sea level rise has more than doubled in just the last decade. Hay et al (2015) Probabilistic reanalysis of twentieth-century sea-level rise, Nature Jeremy Fyke Postdoctoral researcher, Los Alamos National Laboratory: Global average sea level is unambiguously rising. Regions where sea level is falling are regions where local sea level signals are large enough to counteract the global trend—for example, in Baffin Bay and parts of Scandinavia, where continued residual land uplift is continuing, associated with the unweighting of the land from loss of last glacial maximum ice sheets."
https://science.feedback.org/review/there-are-clear-evidence-for-climate-change-contrary-to-claims-by-john-coleman/,Incorrect,"Derek Utley, John Coleman, 2019-02-22","Climate change is not happening, there is no significant man-made global warming now, there hasn't been any in the past, and there's no reason to expect any in the future.",,"Factually inaccurate: The warming of Earth's climate has been unequivocally documented by measurements of many types, including surface station and ocean records, multiple sources of satellite data, and effects like shrinking glaciers. Inadequate Support: Based on multiple lines of evidence, scientists have concluded that human activities are clearly the dominant cause of climate change. ","Coleman's central claim in this video—that there is no human-caused climate change—is contradicted by a wealth of evidence and decades of published, peer-reviewed, scientific research. There is no evidence to support his claim.","There's no question about it. Climate change is not happening, there is no significant man-made global warming now, there hasn't been any in the past, and there's no reason to expect any in the future.",,"Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: [This comment is taken from an earlier review of a similar claim.] This claim is not accurate. Global temperature datasets, developed by a number of independent research groups, show robust warming in the troposphere and at the Earth’s surface. The radiative effect of carbon dioxide has also been observed[1]. Considering multiple lines of evidence, the IPCC concluded that it is “extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century.” More recent analysis of satellite data shows that tropospheric warming from the satellite record is pronounced and cannot be explained by natural climate variability alone[2]. 1 – Feldman et al (2015)Observational determination of surface radiative forcing by CO2 from 2000 to 2010, Nature 2 – Santer et al (2017)Tropospheric Warming Over The Past Two Decades, Scientific Reports Baird Langenbrunner Associate Editor, Nature Climate Change: [This comment is taken from an earlier review of a similar claim.] If we’re assuming [Coleman is] talking about Earth since the industrial revolution, when humans started ramping up fossil fuel burning, then he’s quite wrong. There has been very clear and measurable warming since this time period—this has been confirmed time and time again using station data and satellite measurements and it matches well with predictions based on increases in greenhouse gas concentrations. Even in the brief periods when the surface temperature warms less quickly, the oceans continue to warm, which together with the atmosphere accounts for all the extra heat predicted by increased greenhouse gas concentrations. First, greenhouse gases are well studied, and their properties are nonnegotiable: They absorb and re-emit longwave radiation, whether they’re in a laboratory setting or in the real atmosphere. To back this up with historical evidence, scientists have known since the 1860s that CO2 is a greenhouse gas and since the 1890s that this will affect the heat budget of the Earth through warming. Even then, these claims were based on empirical evidence, and they’re supported by decades of laboratory research. Second, the link between increased greenhouse gas concentrations and warming continues to be supported by research in the last two decades. One study from 2001[1]used satellites to measure the type of energy entering and exiting Earth’s atmosphere and concluded that increases in greenhouse gases were responsible for extra heat measured between 1970 and 1997. The authors state that their results “provide direct experimental evidence for a significant increase in the Earth’s greenhouse effect that is consistent with concerns over radiative forcing of climate.” (Here, the term “radiative forcing” refers to the extra energy trapped in the atmosphere by greenhouse gases, cause warming.) A more recent study[2]arrived at similar conclusions, confirming predictions of the greenhouse effect in Earth’s atmosphere and providing “empirical evidence of how rising CO2 levels … are affecting the surface energy balance.” In other words, rising CO2 was linked directly to warming, even when things like plant uptake of CO2 were considered. 1 – Harries et al (2001) Increases in greenhouse forcing inferred from the outgoing longwave radiation spectra of the Earth in 1970 and 1997, Nature 2 – Feldman et al (2015)Observational determination of surface radiative forcing by CO2 from 2000 to 2010, Nature Mark Richardson Research Associate, Colorado State University/NASA JPL: [This comment is taken from an earlier review of a similar claim.] [These] comments would have been fair in 1896 when Svante Arrhenius calculated that we could cause serious global warming[1]. World temperatures measurements began in the 1800s and show a warming burst since the 1970s. Last year we checked with satellite scans of the ocean[2], confirming the accuracy of the surface measurements. Global warming is measured fact. Working out the culprits has been like Crime Scene Investigation: Physics Edition. Some evidence comes from a facility in Billings, Oklahoma. Parts of air like water vapour and carbon dioxide naturally glow with infrared heat at very specific frequencies. The Billings site has a device that measured an incredibly precise “fingerprint” of the sky’s heating. Investigators reported in 2015[3] that they found fingerprints across the sky with a clear match on the heating trigger. Below the blue line is the file fingerprint for carbon dioxide (CO2) heating, which we release into the air when we do things like burn coal & oil. This file fingerprint comes from basic physics backed by precise lab readings. The red line is the measured fingerprint in the sky over Billings and is a rock solid match. Each spike is extra heat coming down from the extra CO2 molecules that is heating us up. Measurements in Alaska and from satellites[4]confirm this. This is just one slide in the huge folder of empirical evidence showing human activity to be the main cause of recent warming. 1 – Arrhenius (1896)On the Influence of Carbonic Acid in the Air upon the Temperature of the Ground,Philosophical Magazine and Journal of Science 2 – Hausfather et al (2017)Assessing recent warming using instrumentally homogeneous sea surface temperature records, Science Advances 3 – Feldman et al (2015)Observational determination of surface radiative forcing by CO2 from 2000 to 2010, Nature 4 – Harries et al (2001) Increases in greenhouse forcing inferred from the outgoing longwave radiation spectra of the Earth in 1970 and 1997, Nature Shaun Lovejoy Professor, McGill University: [This comment is taken from an earlier review of a similar claim.] Let’s say you are given only three pieces of information: a) The annual average value of the global temperature from 1880 to 1909 b) The atmospheric CO2 concentration for each year c) The effective climate sensitivity With only this, the temperature over the 104 years between 1909 and 2013 could be incredibly well forecast (black line in the figure below), indeed to about an accuracy of ±0.22 °C (purple lines, 90% confidence limits). This tight limit includes the so-called “pause” of the early 2000s. Knowing only the CO2 therefore allows us to predict the temperature more than 100 years into the future. Given that the total change over this time was 1.1 °C, the prediction is correct to within 20%. We know that the CO2 was anthropogenic, therefore its increase was not caused by a change of temperature. We can conclude that CO2 is responsible for much of the change in temperature over the last century. Figure adapted from Lovejoy (2015), Using scaling for macroweather forecasting including the pause, Geophysical Research Letters"
https://science.feedback.org/review/claim-in-the-express-that-low-solar-activity-is-bringing-cold-weather-is-false/,Inaccurate,"Express, Sean Martin, 2019-04-15","Cold weather to grip world as solar minimum to deepen, NASA says",,Factually inaccurate: The headline and article misrepresent the solar activity forecast presented by US science agencies. Misunderstanding of science: A solar minimum would not cause cold weather around the world.,"This headline (and the article below it, as scientists who reviewed the article detail below) misrepresents a NOAA press release by inventing a claim that appears nowhere in that source—the idea that a coming minimum in the Sun's natural 11-year cycle of solar activity will cause cold weather around the world. There is no evidence supporting this.","Cold weather to grip world as solar minimum to deepen, NASA says",,"Rasmus Benestad Senior scientist, The Norwegian Meteorological institute: The NOAA release says nothing about Earth’s weather or climate in the normal sense, but only discusses “space weather”, which is about solar conditions and effects on the upper atmosphere. Hence, the headline of “Cold weather to grip WORLD as solar minimum to DEEPEN, NASA says” is incorrect and strongly misleading.The first paragraph (“A DEEP solar minimum is set to bring a prolonged period of colder temperatures across the globe, NASA has predicted”) is also wrong, as the article says that the next solar cycle is expected to be similar to the preceding one and that they don’t expect a new sort of Maunder Minimum. Moreover, the article says that the steady decline in the solar cycle amplitude has come to an end. The statement that the Sun emits less heat due to a decrease in magnetic waves does not make sense. The reason why the solar output varies with the solar cycle is the presence of flares that accompany the sunspots. The sunspot cycle is connected to the Sun’s magnetic field, not waves. On the other hand, light is the same as electromagnetic waves (waves that are partly magnetic). I think the journalist got the physics mixed up. The cited release says that the decline in solar activity has come to an end, whereas the Express article says it’s going to deepen. The statement that the global temperature dropped by 1.3°C during the Maunder Minimum (1645-1715) is probably picked from an outlier study that is different from most others. A more credible figure is 0.3°C[1]. [1] Shindell et al (2001) Solar Forcing of Regional Climate Change During the Maunder Minimum. Science Michael Lockwood Professor of Space Environment Physics, University of Reading: Firstly, the NASA press release [that this article is based on]: That is reasonable, but there is some academic debate here that is glosses over. It has long been known that there are precursors that can tell you something about the size of the upcoming solar cycle—the level of activity in Earth’s magnetic field during the preceding minimum being the most famous example. We now have a good understanding of that in terms of the long-term variation of the open magnetic flux of the Sun. However, there appears to be a big difference between how predictable the second half of the upcoming solar cycle is (after what is often called the “Gnevyshev gap” that is seen in several solar parameters) compared to the first half. A recent workshop held at ISSI, Bern (The International Space Science Institute) found that although the first half of the cycle is predictable, the second half is much less predictable and indeed, the current solar cycle (numbered 24) is a good example of that. Apart from that, the NASA press release is reasonable and well informed.However, the Express article is a classic example of “spinning” a bizarre narrative out a few wildly exaggerated and misinterpreted facts. This article peddles the endlessly repeated but wholly incorrect idea that the Maunder minimum gave a period of global low temperatures (misleadingly called the “little ice age” although it was not an ice age of any kind). The article is probably wrong in suggesting that solar activity will be lower than in was in 2007/8, and to relate such a minimum between cycles (lasting at most a year) to the 50-year Maunder minimum (when there were no cycles at all) is, frankly, bizarre. The statement that the Sun gives off more heat at sunspot maximum is correct. However, the article doesn’t mention that it is very small—only a 0.1% variation. The explanation as “magnetic waves” is meaningless—the lower emission at sunspot minimum is really because there are fewer small magnetic flux tubes called faculae threading the solar surface. “experts are expecting the solar minimum to deepen even further before it gets warmer” I know of no such experts. It is true that some indicators of the solar cycle will probably go a little lower than they are now over the next year, before solar activity picks up again in cycle 25. However, based on past solar cycles, the Total Solar Irradiance (the total heat and light we get from the Sun) decrease from here to its next minimum will be about 0.01% at the very most, and more likely 0.001%. (See Figure below) Figure – Composite Total Solar Irradiance as daily values plotted in different colors for the different originating experiments.Source “An international panel of researchers led by NASA and NOAA has released a new prediction for the solar cycle: The current solar minimum is going to deepen, potentially reaching a century-class low in the next year or so.” The first half is true, but the second half has come from a number of amateur space weather websites and its provenance is not at all clear—it is not in the official panel press release. The “potentially” is a significant caveat. To do that, this minimum would have to be deeper than the last one (between cycles 23 and 24 in 2008/9)—that is “potentially” possible but now appears to be very unlikely indeed. “The last time a deep solar minimum was in effect was the Maunder minimum, which saw seven decades of freezing weather, began in 1645 and lasted through to 1715, and happened when sunspots were exceedingly rare. During this period, temperatures dropped globally by 1.3 degrees celsius leading to shorter seasons and ultimately food shortages.”This is so full of nonsense it’s hard to know where to begin. Firstly, the Maunder Minimum was a 50-year period with no solar cycles— not a minimum between cycles. As I said above, the upcoming minimum is VERY unlikely to be deeper than the last one in 2008/9. Most importantly, the Maunder minimum was NOT (repeat NOT) a period of decades of freezing weather. It was a period when Europe had a higher fraction of cold winters but summers were, if anything, warmer in the Maunder minimum (as seen, for example, in the central England Temperature measurements) and paleoclimate data show a longer interval of slightly lower global temperatures (often massively misleadingly called the “little ice age”) which began long before the Maunder minimum and didn’t end until after the Maunder minimum was over. The idea that the Maunder minimum gave periods of unremitting cold is just wrong—it is often quoted but it is totally wrong. The claimed drop of 1.3°C in the Maunder minimum is a ludicrous figure. The Figure below (from Owens et al paper[2]) shows any drop that could possibly be associated with the Maunder minimum is 0.2 °C (and Owes et al show that is not statistically significant). That minimum was almost 1.3 °C lower than today’s values because of 1.1 °C of anthropogenic greenhouse warming since just before and just after the Maunder minimum. Figure – A comparison of solar activity and northern hemisphere climate from AD 800 to AD 2016. Top: Sunspot number, from direct telescopic observations (black) and reconstructed on the basis of 14C concentrations in tree trunks (red). Bottom: Northern hemisphere temperature anomaly, ΔT, (relative to the 1961–1990 mean) for paleoclimate reconstructions, as presented in the IPCC fifth assessment report. Colours, from white through red, show the probability density function (PDF), while the white line shows the PDF maximum value (or mode).The blue line shows ΔT from the instrumental record (HadCRUT4). (Source) “Vencore Weather, a meteorological website, said: ‘Low solar activity is known to have consequences on Earth’s weather and climate …. ‘” I don’t know who Vencore Weather are but that statement is wrong. As I said, it is often repeated but is wrong. The article appears to be citing NOAA when it says “Space weather and terrestrial weather (the weather we feel at the surface) are influenced by the small changes the Sun undergoes during its solar cycle.” That statement is undoubtedly true about space weather. The statement about terrestrial weather is contentious. There is growing evidence that low solar activity leads to a weaker, more meandering jet stream (almost certainly because UV emissions from the Sun are lower) and this can lead to cold snaps in Europe—but at the same time they cause warmer periods in, for example, Greenland. There is no credible evidence that this leads to a significant drop in global temperatures. The very top of Earth’s atmosphere (the thermosphere, 250 km up and above) is certainly influenced by solar activity. This is important for factors like orbital decay of satellites but has no implications for surface weather at all. It is a space weather effect not a terrestrial weather effect. [2] Owens et al (2017)The Maunder Minimum and the Little Ice Age: An update from recent reconstructions and climate simulations, Journal of Space Weather and Space Climate Climate Feedback: Sensational claims about outbreaks of cold weather caused by solar activity changes appear repeatedly at some outlets despite the lack of past evidence or research supporting this idea. We recently analyzed the spread of a similar story across the webhere. The claims in this Express article are virtually identical to two of their recent articles, and also got repeated by a number of other sites, including Newsflash.one and Climategate.nl. "
https://science.feedback.org/review/breitbart-article-baselessly-claims-a-study-of-past-climate-invalidates-human-caused-climate-change-john-nolte/,-1.9,"Breitbart, by John Nolte, on 2019-04-09.",,"""Scientists Prove Man-Made Global Warming Is a Hoax""",,,,,"This Breitbart article comments on a story by ThinkProgress about a study related to past climate, mistakenly concluding that it invalidates the science that shows human activities are currently altering the climate of our planet. Scientists who reviewed the article explain that it builds on a fallacious reasoning, as if the fact that climate has changed due to natural forcing in the past would make it impossible for human emissions of CO2 to change it now. In reality, the climate of the Earth can be influenced by various forcings, including changes in the Sun’s irradiance and atmospheric concentrations of greenhouse gases, which in turn can be due to natural causes (as has been the case in the past) or activities related to human actions—as is the case currently. All the scientists indicated that the content of the article does not support the claim made by the headline. In addition to Breitbart, a number of other outlets published stories repeating the mistaken claim that this scientific study would disprove the human origin of climate change, including: Climate Change Dispatch,Godfather Politics, Technocracy. You can read the article here. (To read the scientists’ annotations in context, visit the article and install the Hypothesis browser extension.) UPDATE (15 April 2019): After publishing, we received a comment from an author of the study that the Breitbart article is commenting on, which is now included below. Additionally, Mark Richardson’s name was not correctly displaying above his annotation comment, causing it to appear as part of the comment above it. This error has been fixed. GUEST COMMENTS: Matteo Willeit Postdoctoral Researcher, Potsdam Institute for Climate Impact Research: As the lead author of the paper published in Science Advances on which this article is based on, I would like to state that it is a misrepresentation of the findings published in Willeit et al (2019)*. Our paper does not in any way disprove the human origin of current climate change. On the contrary, our model, which is able to reproduce the last 3 million years of natural climate variability, clearly shows that the rise of atmospheric CO2 concentration since the industrial revolution can not be explained by natural climate processes. Willeit et al (2019) Mid-Pleistocene transition in glacial cycles explained by declining CO2 and regolith removal, Science Advances REVIEWERS’ OVERALL FEEDBACK: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Richard Betts Professor, Met Office Hadley Centre & University of Exeter: Woefully ignorant. We are certain that humans are responsible for the current rise in atmospheric CO2 concentrations, because the amount being emitted is more than enough to explain the amount building up in the atmosphere. Climate scientists are well aware that there are also natural changes in the carbon cycle that have led to higher CO2 concentrations in the past, and in fact this gives more of a cause for concern rather than less, because it shows that a warming climate can cause natural carbon sinks to weaken and therefore further accelerate the rise in CO2. Mark Richardson Research Associate, Colorado State University/NASA JPL: The new research shows that a past high CO2 period had lots of global warming, just like we expect from today’s human-driven CO2 changes. Breitbart’s argument is that since CO2 changed naturally before, we can’t change it now. This is like saying that fires happened naturally before so there is no way any of us could cause a fire. It’s wrong. Benjamin Horton Professor, Earth Observatory of Singapore: Incredibly misleading. The Pliocene is a warning of what CO2 levels can do to the planet Ken Caldeira Senior Scientist, Carnegie Institution for Science: It is hard to imagine that a well-intentioned person can so profoundly misunderstand the science. Assuming the author is acting in good faith, this article provides evidence that motivated reasoning can produce results that appear delusional to well-informed people. By the reasoning of this article, if a rock rolled down a hill three million years ago, no human can be responsible for rolling a rock down a hill today. The fallaciousness of this reasoning is astounding. Ted Letcher Research Scientist, Cold Regions Research and Engineering Lab: Without going into any greater detail, this is quite possibly the worst “climate”-related article I’ve ever encountered. The “logic” is completely nonsensical and the writing is of extremely poor quality. This article isn’t worth reading, not even for the shock value. Lindsey Nicholson Postdoctoral research fellow, University of Innsbruck: This article correctly reports the conditions during a warm climate period in past geological time, but then incorrectly and unfoundedly claims that is evidence that human activities are not responsible for Earth’s current climate trajectory. In reality, human activities have been demonstrated robustly by multiple lines of evidence to be profoundly influencing modern climate. Christopher Merchant Professor, University of Reading and UK National Centre for Earth Observation: The article presents us with a false choice between believing that people’s actions today affect climate and believing that the climate of Earth has changed naturally over millions of years. Both these ideas can be true—and both these ideas are true. Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: This article (perhaps deliberately) cherry picks one observation (out of context from the paper) and makes up a whole story about it disproving global warming. The level of misunderstanding about this paper is so high that I cannot be convinced that it is anything other than a wilful attempt to misguide their readership. Marcus Badger Lecturer in Earth Sciences, The Open University: This article completely misunderstands the point of the science it reports on. Twila Moon Research Scientist, University of Colorado, Boulder: The analysis in this article is wrong, using flawed reasoning to draw incorrect conclusions. Over thousands to millions of years, other natural processes can change the global temperature, including warming it. But the warming occurring now, over less than 100 years, is primarily caused by humans. Annotations: The statements quoted below are from the article; comments are from the reviewers (and are lightly edited for clarity). Yes, you read that correctly, three million — million — years ago CO2 levels on Earth were the same as they are today, but there is one major difference between three million years ago and today… Marcus Badger Lecturer in Earth Sciences, The Open University: This part of the article does accurately report the findings of the paper it links to: CO2 is now higher than it has been for 3 million years. Although not a new result (see Martinez-Boti et al 20151), the linked study by Willeit et al2 has new model simulations looking how climate changed from the Pliocene to the Pleistocene, and demonstrates how declining CO2 levels lead to a change in the climate system. However what follows is largely a misunderstanding of the implications. 1- Martinez-Botí et al (2015) Plio-Pleistocene climate sensitivity evaluated using high-resolution CO2 records, Nature 2- Willeit et al (2019) Mid-Pleistocene transition in glacial cycles explained by declining CO2 and regolith removal, Science Advances Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: The author writes this as if this is something that is a surprise. We all know that the Earth’s CO2 levels were higher at various times in the past. In the Eocene, 50 million years ago, they may have even been four times as high. This is not an issue. In the past, rates of volcanic CO2 emissions globally were higher as continental spreading rates changed, for example. Saying that CO2 isn’t rising now due to humans just because it used to be high in the past is like saying “I didn’t chop the cherry tree down because 40 years ago there was never a cherry tree there”. It is totally unrelated. CO2 levels were the same then as they are now Marcus Badger Lecturer in Earth Sciences, The Open University: Yes, naturally CO2 were as high in the Pliocene 3 million years ago as they are today. We have good records of the past 66 Million years of CO2-driven climate change, and these record a broad decline over that time, with the Pliocene the last time CO2 was naturally as high as it is today following anthropogenic emissions. We have also been told the problem is DEFINITELY NOT a billions-year-old planet running through cycles where the temperature might fluctuate a bit.Marcus Badger Lecturer in Earth Sciences, The Open University: This confounds natural variations in CO2 in the geological past with human-caused emissions today. Yes, CO2 has changed naturally over time, causing changes to climate, but the high levels and rapid increase we are seeing today is because of human-caused emissions. Mark Richardson Research Associate, Colorado State University/NASA JPL: This entire article’s “proof” is just saying that “higher CO2 happened before humans, therefore humans can’t cause higher CO2“. Here are logically identical arguments: “England scored goals before Harry Kane, so Harry Kane can’t score goals” Or in American English: “The New England Patriots scored touchdowns before Rob Gronkowski, so Rob Gronkowski can’t score touchdowns” Or more simply: “Fires happened before humans, so humans can’t cause fires”. So if you agree with this article’s logic and that humans aren’t causing CO2 to rise, you also have to believe that Harry Kane and Rob Gronkowski never scored anything and could never score anything, and that no fire has been caused by a human ever. Human-caused global warming, goals by Harry Kane, touchdowns by Rob Gronkowski, and fires set by people are all in the same boat. We have enormous evidence that they exist. Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: We are well aware that there are climatic fluctuations through geological time. Huge numbers of scientists study how the Earth’s climate has fluctuated before, and we know what caused those changes. Current warming is not related to any natural climate cycle, or process, or astronomic phenomenon. According to the study, scientists also discovered that during this period of Global Warming “there were no ice sheets covering either Greenland or West Antarctica, and much of the East Antarctic ice sheet was gone.” Marcus Badger Lecturer in Earth Sciences, The Open University: This is where the real logical fallacy of this article becomes clear. Indeed, when CO2 was naturally as high as we have caused it to be now, the world was much warmer than today because of the naturally higher CO2. It therefore follows that the high CO2 levels we have created in the atmosphere will lead to a warmer world, just like the Pliocene. “there were no ice sheets covering either Greenland or West Antarctica, and much of the East Antarctic ice sheet was gone.” How is this possible 2,999,971 years before Arnold Schwarzenegger bought his Hummer? Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: What this study tells us is that the last time CO2 was as high as 410 ppm (back then through natural causes), there was no ice on Greenland or West Antarctica. What this means is that we can potentially expect (once the climate has equilibrated to its new CO2 levels) that these ice bodies will melt in the future from anthropogenic CO2 release. If this happens, the sea level will rise by metres, and many coastal and lowland cities will be affected. In a way I have to profess my admiration- how a news outlet could take a paper presenting evidence that we should be very worried about CO2 being 410 ppm, and turns it into a paper that “debunks climate change”, is beyond me. It really is a feat that must have taken a lot of imagination and creative thinking. How is this possible 2,999,971 years before Arnold Schwarzenegger bought his Hummer? Richard Betts Professor, Met Office Hadley Centre & University of Exeter: Because the amount of CO2 naturally present in the atmosphere depends on how much is being released or taken up by the oceans, land ecosystems, and chemical reactions involved in rock weathering. These change naturally, but gradually, over thousands or millions of years. Human emissions of CO2 are merely adding an extra factor to the equation, but it is one which has a big effect over much short timescales (the last few decades). Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: It is possible because CO2 sources (e.g. volcanic degassing) and CO2 sinks (e.g. from chemical weathering of the Earth’s surface) were differently balanced back then. It is not a mystery, it is well understood science that has countless papers about it, and a serious journalist (if they profess to be one) would have made some effort to educate themselves before writing such an article.a study that totally debunks the whole concept of man-made Global Warming Marcus Badger Lecturer in Earth Sciences, The Open University: The study does the complete opposite of this, by showing that high levels of CO2 has caused a warmer world in the past, it confirms what we know about how anthropogenic CO2 emissions are and will continue to warm the planet. running through cycles where the temperature might fluctuate a bit. Richard Betts Professor, Met Office Hadley Centre & University of Exeter: The Earth’s climate has always varied, even before humans began to influence it. Climate scientists have always been very clear about this. But human-caused emissions of CO2 and other greenhouse gases have now added a new cause of climate change in addition to the existing causes of natural climate variability. How is that possible 2,999,945 years before Americans moved to the suburbs and lit up the charcoal grills? Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: Again, this is possible because at various times in the Earth’s history, sources and sinks of CO2 into the atmosphere have had varying strengths. These are natural changes in CO2 levels that have slowly happened for 100s of millions of years. However, modern CO2 rise is faster than any rise ever seen in the last 66 million years* and quite possibly ever before in the geological record. Zeebe et al (2016) Anthropogenic carbon release rate unprecedented during the past 66 million years, Nature Geoscience a study that totally debunks the whole concept of man-made Global Warming, Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: This study does no such thing. This is factually inaccurate. But-but-but-but Alexandria Ocasio-Crazy told me we only have 12 years! Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: The 12-year figure quoted comes from the 2018 UN “Special Report on Global warming of 1.5ºC,” released last October. In this report, the year 2030—12 years from now—is given as the “point of no return”, if we keep releasing CO2 at our current rate. What this means is that after this point, it is almost impossible to imagine how CO2 in the atmosphere could ever be brought back down to levels needed to keep global temperatures less than 1.5 ˚C warmer. This figure comes from the IPCC report scientists—hundreds of scientists from different fields working all around the world. The article has taken this figure out of context, and is comparing it to something very different. What ThinkProgress says is related to the timescales it takes for the maximum effects of the CO2 released now to take hold. This is not in conflict with the IPCC figure of 12 years cited by AOC—this report talks about the year we must stop releasing CO2 by in order for the long term knock on effects of this CO2 release to not be so detrimental to humankind. Marcus Badger Lecturer in Earth Sciences, The Open University: This confuses the time left to start seriously cutting emissions, with the long tail of impacts that those emissions have. As noted above in this article, there are lags in the climate system that mean CO2 emissions now will continue to warm the planet for a long time, and some long-acting positive feedbacks (like ice melting) take time. what this study proves is that there is nothing we can do to stop the Earth’s naturally occurring climate cycles. Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: This study does absolutely no such thing. Its topic wasn’t even related to showing climate cycles—the subject of the paper is looking at the effect on CO2 of ice sheets scraping soil and weathered rock off the Earth’s surface over ice ages. CO2 rise and warming that is happening now is entirely something that we have caused (see here for some helpful pointers). We can control our CO2 release, and so we can control our current rate of warming. What the background conditions do over millions of years is not the point, and is only used in this article as a distraction. nothing we can do to stop the Earth’s naturally occurring climate cycles. Richard Betts Professor, Met Office Hadley Centre & University of Exeter: Actually, studies suggest that we may already have postponed the next ice age by adding extra CO2 to the atmosphere which will take a long time to be removed by natural processes, and hence has committed the Earth to warmer temperatures than it would otherwise have had. Marcus Badger Lecturer in Earth Sciences, The Open University: This is not true, and there is good evidence that human CO2 emissions stopped the initiation of another ice age* Ganopolski et al (2016) Critical insolation–CO2 relation for diagnosing past and future glacial inception, Nature"
https://science.feedback.org/review/blaze-article-badly-misrepresents-study-of-greenlands-jakobshavn-glacier/,Flawed reasoning,"The Blaze, Chris Enloe, 2019-03-26","[O]ne of the previously fastest shrinking glaciers in the world is growing again, calling into question the narrative that rapid climate change [...] poses a significant threat to the existence of the human race",,"Fails to grasp significance of observation: A temporary re-advance of a glacier driven by variability of ocean currents is not a reversal of the long-term, human-caused trend of warming and ice loss.  Flawed reasoning: Observing the multi-faceted behavior of an individual glacier does not enable one to conclude that global climate change is not dangerous.","This claim badly misrepresents a study showing that a temporary movement of cooler ocean water against Greenland's Jakobshavn Glacier caused the previously retreating ice to re-advance slightly. The study does not, in any way, imply that global climate change and sea level rise are not dangerous. It simply illustrates the local effects that glaciologists study in order to understand all the factors that can affect individual glaciers.","[A]ccording to new data from NASA, one of the previously fastest shrinking glaciers in the world is growing again, calling into question the narrative that rapid climate change — i.e., global warming — poses a significant threat to the existence of the human race, let alone the entire planet.",,"Lauren Simkins Assistant Professor, University of Virginia: “…from NASA…“: Although NASA-based scientists and NASA-funded data are strongly involved in the study, scientists from other domestic and international institutions are also involved. This is a minor point, but readers might be inclined to think NASA is solely responsible for the study. “…one of the previously fastest shrinking glaciers in the world is growing again…“: While this statement is by itself accurate, it is misleading in that the glacier—despite thickening and slowing in places since 2016—remains in a state of ice mass loss where inputs do not make up for outputs. The glacier is still hauling ice into the ocean at very fast rates compared to glaciers worldwide. Despite thickening within tens of kilometers from the ice front (a.k.a. margin or grounding line), ice losses elsewhere are greater than gains. This can happen two ways—overall thinning (accelerated ice flow leads to thinning if gains cannot account for the speed up) and calving of ice from the margin. “…rapid climate change — i.e., global warming…“: It is important to clarify that the current “global warming” we are experiencing today produces a variety of responses in the ocean and atmosphere, and that ocean temperatures are not homogeneous across the ocean or even through a vertical slice of the water column. Anthropogenic atmospheric warming kicked off and continues to alter many other feedbacks that modify natural ocean and atmosphere patterns. For example, as the cited study discusses, how much heat is lost by the surface ocean depends heavily on the density of ocean water masses, which is fundamentally controlled by ocean salinity and temperature. If the depth of the ocean that is mixing increases due to, for example, decreased ocean-ice cover and ocean water freshening due to glacier meltwater input, the ability of the ocean to retain and absorb heat is altered on a seasonal basis. The study demonstrates that the ocean has memory of wintertime heat loss, which led to cooling that persists beyond a single season. Therefore, one winter’s ocean cooling leads to subsequent winter waters being colder. “…poses a significant threat to the existence of the human race, let alone the entire planet…” – The physical planet will be fine eventually; however, all the living stuff, including us, is not necessarily biologically equipped to adapt to such rapid environmental changes. I am not aware of any peer-reviewed articles that link modern global warming to the extinction of the human race, and find the interweaving of the topics of periodic glacier thickening and the existence of the human race irresponsible and alarmist for the sake of gathering attention. One question that remains is how long will these cold ocean conditions near the glacier last? That is a question that we don’t know the answer to. Other than a key conclusion being that the glacier is extremely sensitive to ocean temperature fluctuations, the study finds that the glacier is still flowing at extremely fast rates and discharging enough ice into the ocean to keep Jakobshavn Isbrae a major player in global sea level rise. The findings are not well represented in the above quote. Henning Åkesson Postdoctoral researcher, Stockholm University and Bolin Centre for Climate Research: The Blaze article is misleading. To me, the study shows just how sensitive ice sheets are to changing ocean temperatures, and how quickly glaciers can respond. The Blaze quotes the AP, saying that Jakobshavn’s sudden growth likely was caused by natural and temporary cooling of the North Atlantic. We know that this “ocean weather” comes and goes, just like the weather outside. We really need to put on our long-term goggles here. A cold winter day doesn’t mean global warming is suddenly off the table. Similarly, glacier melt will continue because the long-term trend is clear, both the ocean and the atmosphere is warming, attacking glaciers from both below and above. Twila Moon Research Scientist, University of Colorado, Boulder: The new observations of slowing for Jakobshavn Glacier in NO WAY call into question rapid climate change. Individual glacier behavior—such as glacier speed, thickening, and retreat—responds to climate change AND to local conditions and short-term (year-to-year) variations. Non-climate elements influencing glacier behavior include land shape underneath and along the side of a glacier, short-term changes in air temperature and precipitation, and ocean temperature and motion. Scientists do not expect individual glaciers, like Jakobshavn, to change steadily as the global climate warms. Recent behavior of Jakobshavn Glacier does not change any of the scientific consensus on the rapidity of climate change, and urgency regarding our need to address it. Alexander Robel Assistant Professor, Georgia Tech: The only part of this statement that is supported by the Nature Geoscience study is “[A]ccording to new data from NASA, one of the previously fastest shrinking glaciers in the world is growing”. Nothing after that part of the sentence is supported or even addressed by the Nature Geoscience paper. In particular, it is not clear what is meant by “again” since it is not necessarily the case that the glacier was growing as much before the recent period of retreat. Also, there are many glaciers around Greenland, not just Jakobshavn, which have been undergoing retreat over the last few decades, and these glaciers have not necessarily started growing in the last few years. Individual glacier systems, particularly those in contact with the ocean, undergo strongly heterogeneous responses to climate change and climate variability. This is an ongoing area of research within glaciology. However, there are many independent lines of evidence from satellites and field observations, which have shown that on net, the Greenland and Antarctic Ice Sheets have been losing mass over at least the last 20 years, contributing to global sea level rise. This total mass loss has continued over the last few years, regardless of what has occurred at any individual glacier."
https://science.feedback.org/review/caleb-rossiter-falsely-claims-that-climate-models-are-running-very-hot/,Inaccurate,"The Hill, Caleb Rossiter, 2019-03-06",The models predicted about three times the amount of warming in the world we’ve seen since [1988].,,Factually Inaccurate: Observed warming has consistently fallen within the range of climate model simulations over time.,"Climate scientists use models to simulate and study different aspects of Earth's climate system, and to project the rate of global warming caused by human activities. These models do, in fact, simulate the rate of global warming well, and models run in the past accurately projected the rate of warming we are currently experiencing—that includes model projections from 1988.",The models started in about 1988 to make predictions 30 years hence. Guess what? The models predicted about three times the amount of warming in the world we’ve seen since then. So the models are running very hot.,,"Reto Knutti Professor, ETH Zürich: [This comment is taken from an evaluation of a similar claim.] The statement that climate models overestimate the warming in response to CO2 is incorrect; it is based on either too short time periods that are dominated by natural variability, by the comparison of models with datasets that do not have global coverage, by comparing to models that were run many years ago with emissions and forcings that differed from what actually happened, by the use of oversimplified energy balance models1, or a combination of it. Recent studies have shown that once the changes in climate feedbacks over time2, datasets with full coverage are considered3 and all forcings are considered, the agreement between predicted and observed warming is excellent, even over the recent hiatus period4. It is remarkable that even projections made decades ago with climate models that were much simpler (and were running on computers that were likely slower than a mobile phone today) were quite accurate5,6,7. 1- Knutti and Rugenstein (2015) Feedbacks, climate sensitivity and the limits of linear models, Philosophical Transactions of the Royal Society A 2- Armour (2017) Energy budget constraints on climate sensitivity in light of inconstant climate feedbacks, Nature Climate Change 3- Richardson et al (2016) Reconciled climate response estimates from climate models and the energy budget of Earth, Nature Climate Change 4- Medhaug et al (2017) Reconciling controversies about the ‘global warming hiatus’, Nature 5- Stouffer and Manabe (2017) Assessing temperature pattern projections made in 1989, Nature Climate Change 6- Fischer and Knutti (2016) Observed heavy precipitation increase confirms theory and early models, Nature Climate Change 7- Allen et al (2013) Test of a decadal climate forecast, Nature Geoscience Patrick Brown Assistant Professor, San Jose State University: [This comment is taken from an evaluation of a similar claim.] This argument reached a peak in popularity around 2012/2013 when the “hiatus” was still ongoing (i.e. when the divergence between observed and modeled global temperature was at its largest). Even then, however, it was shown that you cannot conclude much about sensitivity to CO2 from such short-term fluctuations1. Similarly, Brown et al. (2015)2 showed that decade-long periods without warming are to be expected and that there was/is a 70% chance of seeing at least one 11-year period with no warming between the years of 1993-2050 under a “middle of the road” emissions scenario. Since then, observed warming has surged and, as of 2016, observations are warmer than the average prediction from climate models (see figures below). 1- Marotzke and Forster (2015) Forcing, feedback and internal variability in global temperature trends, Nature 2- Brown et al (2015) Comparing the model-simulated global warming signal to observations using empirical estimates of unforced noise, Scientific Reports Figure – Modeled global surface temperature (RCP 4.5 emissions scenario) compared to observed temperature (NASA GISS). Source Figure – Updated version of IPCC AR5 Figure 11.25a, showing observations and the CMIP5 model projections relative to 1986-2005. The black lines represent observational datasets (HadCRUT4.5, Cowtan & Way, NASA GISTEMP, NOAA GlobalTemp, BEST). Source Markus Donat Research Fellow, University of New South Wales: [This comment is taken from an evaluation of a similar claim.] For example, this study by Rahmstorf and colleagues* shows how projections from past IPCC reports (future projections starting in 1990 and 2000) very well predicted the observed temperature changes since then. Figure – Observed annual global temperature, unadjusted (pink) and adjusted for short-term variations due to solar variability, volcanoes and ENSO (red) compared to the scenarios of the IPCC (blue range and lines from the third assessment, green from the fourth assessment report). Source: Rahmstorf et al (2012) Rahmstorf et al (2012) Comparing climate projections to observations up to 2011, Environmental Research Letters Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: [This comment is taken from an evaluation of a similar claim.] At the surface models predict a rate of warming of 0.2°C per decade since 1970, while NASA observes warming of around 0.18°C during the same period[…] Similarly, the observations from all the different groups that measure global surface temperatures are well within the envelope of model projections: Over a longer timeframe, since we first started observing global temperatures in the late 1800s, models have also matched observations fairly well: Cowtan et al (2015) Robust comparison of climate models with observations using blended land air and ocean sea surface temperatures, Geophysical Research Letters Climate Feedback: This RealClimate post analyzes a famous set of climate model projections presented in 1988 by NASA’s James Hansen. Comparing global temperature data to the model scenario with the greenhouse gas emissions closest to what actually happened since then shows that the model was accurate. Source: RealClimate"
https://science.feedback.org/review/senator-sanders-claim-that-climate-change-is-making-tornadoes-worse-isnt-supported-by-published-research/,Misleading,"Facebook, Bernie Sanders, 2019-03-04","The science is clear, climate change is making extreme weather events, including tornadoes, worse.",,"Overstates scientific confidence: Research clearly shows that certain types of weather extremes are increasing as a result of climate change, but it is not clear how tornadoes are responding to a warming climate.","Human-caused climate change is known to be having an influence on some types of weather extremes, including heat waves and intense rainstorms. However, scientists aren't certain about certain other types of weather, either because historical data are insufficient to detect trends or because it's unclear how those weather patterns will respond to warming. It is not currently clear how climate change affects tornadoes.","The science is clear, climate change is making extreme weather events, including tornadoes, worse.",,"Andreas Prein Project Scientist, National Center for Atmospheric Research: Sen. Sanders’ is partly correct since there is a lot of scientific evidence that climate change increases the frequency and intensity of many extreme events such as heat waves, droughts, wildfires, or extreme rainfall. However, it is not clear if climate change will make U.S. tornadoes worse or more frequent. The observational record does not show any significant change in the frequency of U.S. tornadoes in the last 60 years but there is a tendency that more tornadoes occur during big outbreak days such as in the recent Alabama event[1]and there are spatial shifts in the occurrence of tornadoes[2]. Whether these changes are related to climate change is, however, unclear. Adam Sobel Professor, Columbia University: Sen. Sanders’ statement is inaccurate with regard to tornadoes. It is possible that climate change may be influencing tornadoes, but the evidence for that so far is weak, and our understanding of the problem is poor at this point. So it is not true that “the science is clear” on this topic. Longer answer: Sanders would have been broadly correct if he had left out the “including tornadoes” phrase. There is strong evidence that climate change is making some kinds of extreme events worse. Heat waves and heavy rain events are perhaps the best examples; hydrological drought and wildfire (both being influenced by warmer temperatures in relatively simple ways) are others. The influence of climate change on some other kinds of extreme events is more uncertain, and tornadoes are perhaps the most uncertain of all. There is no agreement among scientists about even what influence climate change should have on tornadoes. Our physical understanding of what controls tornadoes suggests that global warming should have at least two different effects[see below]; these act in opposite ways and we don’t know which is stronger, so we don’t know if there should be more or fewer tornadoes with warming, for example. Climate models can’t simulate tornadoes so they are little help, and the observations thus far are not much help either. It is true that there are observed recent historical trends in some measures of tornado activity, as in the paper[2] [cited by the article Sen. Sanders was sharing on Facebook]. But those are mostly spatial shifts in where tornadoes have been occurring recently and do not indicate an overall increase in either the numbers or intensities of tornadoes nationwide, nor is there any good evidence that those trends result from climate change as opposed to natural variability. The authors of the study say as much: “At this point, it is unclear whether the observed trends in tornado environment and report frequency are due to natural variability or being altered by anthropogenic forcing on the climate system.” Climate Feedback: It is likely that a warmer, moister world would allow for more frequent instability as measured by the convective available potential energy which is fueling tornadoes[3]. However, it is also likely that a warmer world would lessen chances for wind shear, leading to fewer tornadoes. Climate change also could shift the timing of tornadoes or the regions that are most likely to be hit, with less of an impact on the total number of tornadoes. Figure — Map showing the increasingly favorable tornado conditions in the SE and a decrease in the west as measured by the Significant Tornado Parameter (STP). The STP shows when the atmospheric wind shear and instability are favorable for tornadoes to develop. (from Gensini and Brooks[2]) 1- Brooks et al (2014) Increased variability of tornado occurrence in the United States, Science 2- Gensini and Brooks (2018) Spatial trends in United States tornado frequency, Climate and Atmospheric Science 3-Diffenbaugh et al (2013)Robust increases in severe thunderstorm environments in response to greenhouse forcing, PNAS"
https://science.feedback.org/review/western-journal-op-ed-deceives-readers-with-completely-unsupported-claims-jay-lehr-tom-harris/,-2,"The Western Journal, by Jay Lehr, Tom Harris, on 2019-02-20.",,"""Media Hysteria: Climate Change ‘Heat Records’ Are a Huge Data Manipulation""",,,,,"This op-ed published by The Western Journal, written by two members of think tanks opposed to the conclusions of climate science, makes several different types of claims about global temperatures and global temperature data. The authors attempt to argue that global temperatures are not increasing by cherry-picking some local examples of weather extremes. The headline further claims that temperature data have been “manipulated”. Scientists who reviewed the article found that it provided no support for any of its claims, which contradict existing research and data analysis.The argument it attempts to make suffers from flawed reasoning, pretending that a cold record at some location decades ago would mean that the last few years of global average temperatures haven’t been the warmest on record. The reviewers indicated that the content of the article does not support its headline. UPDATE (26 February 2019) The Western Journal has retracted this op-ed, providing the following message in its place: “This Op-Ed has been retracted for failing to meet The Western Journal’s Editorial Standards. After publication, a number of factual claims made in the Op-Ed were determined to have been untrue. The decision was then made to retract the piece. Before we had done that, questions were raised about the methodology used by its authors to reach their conclusions, but because the decision to retract had already been made, The Western Journal did not investigate the validity of those questions. We note them here only for the record. We apologize for publishing material in violation of our Editorial Standards of factual accuracy and for any confusion we might have caused by doing so.” You can read an archived copy of the op-edhere. You can also install the Hypothesis browser extension to read the scientists’ annotations in context.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Mark Richardson Research Associate, Colorado State University/NASA JPL: This article misrepresents research, makes assertions without evidence, and hides key information that destroys its main point. It will deceive readers. Peter Kalmus Data Scientist, Jet Propulsion Laboratory: This is one of the most scientifically inaccurate articles I have ever seen. The authors, apparently intentionally, provide false information and engage in extreme cherry-picking to mislead the public about climate change. Victor Venema Scientist, University of Bonn, Germany: The authors do not even write about, let alone provide any evidence for, the data manipulation claim in their headline. They even admit themselves that their home-brew way of studying changes in extremes is really bad. If I were paying their salaries, I would want my money back. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Annotations: The statements quoted below are from the article; comments are from the reviewers (and are lightly edited for clarity). [headline:] Climate Change ‘Heat Records’ Are a Huge Data Manipulation Victor Venema Scientist, University of Bonn, Germany: This is the biggest and most ludicrous claim of the article—the claim that will be read most and shared most on social media—and the article provides no evidence the data was manipulated. The idea that climate change is producing heat records across the Earth is among the most egregious manipulations of data in the absurd global warming debate. Victor Venema Scientist, University of Bonn, Germany: Just to be clear, the main claim of climate science is that the global average temperature is increasing. The increase of heat waves is one of the many consequences of this. The article confusingly uses the term “record” in two meanings. The term records can be used for the observations that were recorded by meteorologists over the last centuries. The term “records” is mostly used for the highest or lowest value ever seen. In an article about the highest and lowest temperatures, it is best to avoid using the term records for the recorded data. The article also confusingly keeps on jumping between claims about local records in daily mean temperatures and claims about the long-term global mean temperature. Local temperatures are by their nature more variable than global average temperatures, daily temperatures are by their nature more variable than long-term average temperatures, records are by their nature more random than averages. With all the extra variability in the local daily records the authors can easily cherry pick a few data points that fit their narrative. What would make their case stronger would be if they actually analysed all the data, engaged with the existing scientific literature and made their own contribution to our scientific understanding by publishing a scientific paper. The cherry picking exercise in this Western Journal article does not contribute to our scientific understanding of the world. On Feb. 7, several major newspapers carried stories of the declaration by NASA and NOAA that the past five years have been the warmest on record. Victor Venema Scientist, University of Bonn, Germany: This is a claim about the global mean temperature and an accurate one: the last five years are the five hottest years for the period for which we have instrumental observations and likey much longer. Sadly, these supposed experts use mathematical equations that do not jibe with reality over the past 140 years. Victor Venema Scientist, University of Bonn, Germany: Experts tend to use mathematical equations. If the authors would like to claim an equation is wrong, they should state which one and provide a source. Otherwise it is just hot air. Peter Kalmus Data Scientist, Jet Propulsion Laboratory: I would like to see the authors to provide the “mathematical equations” to which they refer. The same climate experts warn that record heat is just the tip of the iceberg. Victor Venema Scientist, University of Bonn, Germany: That is true, climate change causes many other problems for humanity*. IPCC (2014) Impacts, Adaptation, and Vulnerability Actual weather records over the past 100 years show no correlation between rising carbon dioxide levels and local temperatures. Victor Venema Scientist, University of Bonn, Germany: Science only claims a relationship between carbon dioxide levels and the global temperature. Still, it would be nice if the authors would provide a source for their claim. Did the Earth experience its highest temperature ever this year? The answer is no. Peter Kalmus Data Scientist, Jet Propulsion Laboratory: Does this have any significant bearing on the steadily increasing ocean heat content and annual mean global surface temperature? The answer is no. The coldest temperature ever reported was 129 degrees below zero Fahrenheit in Vostok, Antarctica, in 1983, when Carbon dioxide emissions were five times higher than in 1913. Victor Venema Scientist, University of Bonn, Germany: In 1913 there was only one official research station in Antarctica. It was on Laurie Island in the middle of the Southern Ocean. Vostok Station was founded close to the South Pole by the Soviet Union in 1957. With the spread of weather stations the chance of a low record increases. This may be the clearest way to show that just mentioning a few records is a really bad way to study whether extreme weather has changed. These examples all illustrate that cherry picking record high temperatures in isolated locations tells absolutely nothing about the Earth’s climate. Peter Kalmus Data Scientist, Jet Propulsion Laboratory: This is one of the only scientifically accurate statements in the article. Cherry-picking in general is misleading, which is why scientists—unlike these authors—take extraordinary care not to do it. (While some of the authors’ own cherry-picked records may be true, they in no way support the authors’ argument, and therefore they are contextually inaccurate.) Victor Venema Scientist, University of Bonn, Germany: This is a bizarre ending of this part of the article were the authors admit that their really bad method to study whether the weather becomes more extreme is a really bad method to study whether the weather becomes more extreme. Fortunately, scientist put in more effort to produce reliable knowledge. A good way to access what science knows about changes in extreme weather is the IPCC Special Report on Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation. The authors of this article would have saved the time of many readers had they read up on the state of the science. The strongest heat wave ever recorded [in the US] occurred in July 1936 Victor Venema Scientist, University of Bonn, Germany: People may know this period as the Dust Bowl, where bad land management practices produced bare soil, dust storms, crop failure, and heat waves. This affected especially the maximum temperature, the summer temperature and stations in the Dust Bowl region. Global warming is about global warming. There are other reasons why the temperature changes, but over the last century the main reason is the burning of fossil fuels. Locally, these other reasons can be significant—like the US Dust Bowl. as time progresses and fossil fuel emissions increase, the number of record highs should increase and record lows should decrease.Peter Kalmus Data Scientist, Jet Propulsion Laboratory: In fact, globally, record daily high temperatures are outpacing record daily lows. This is even also the case over the relatively small region of the globe we call the US. See, for example, this Climate Central article. Concurrently a compilation of all days since 1915 when temperatures exceeded 90F shows them decreasing with time rather than increasing in Figure 2. Victor Venema Scientist, University of Bonn, Germany: The figure again has no source, no way to check how it was computed. Days over 90F focuses on maximum temperature and summer days, the data most affected by the Dust Bowl. the data does not support the claim that the United States is hotter than ever as a result of rising Carbon dioxide levels Victor Venema Scientist, University of Bonn, Germany: This would be claim about the average temperature of America and would normally refer to the annual average temperature—that does not follow from summer maximum temperature records. From 1970 until 1998 there was a warming period that raised temperatures by about 0.7 F that helped spawn the global warming alarmist movement. However, since 1998, little warming has occurred while carbon dioxide emissions continue to increase. Mark Richardson Research Associate, Colorado State University/NASA JPL: Warming rate from 1970-1998: +0.15 C/decade, 95 % confidence interval +/- 0.06 C/decade. Warming rate from 1998-2018: +0.18 C/decade, 95 % confidence interval +/- 0.09 C/decade. (Calculated with Berkeley Earth). Odds are that warming after 1998 was faster than warming before 1998. Anyone who looks into the data and has basic analysis skills can see this, so they would not even try to imply that 1970-1998 warming was faster than post-1998 warming. The whole article uses tricks like this to invert reality, and will leave readers deeply deceived. Victor Venema Scientist, University of Bonn, Germany: A quick look at the global temperature curve immediately shows that warming continues after 1998 at about the same rate. Source These facts are completely supported by 4,000 ocean floats Victor Venema Scientist, University of Bonn, Germany: The fact that the Earth is warming is completely supported by ocean floats.Isn’t it time to start ignoring the calamitous annual claims that this is the hottest year on record? Victor Venema Scientist, University of Bonn, Germany: This is again a claim about the annual mean temperature, not about local daily maxima. 2018 was the fourth warmest year. With the last five years being the five warmest years we have a real problem. Putting your head in the sand does not protect what we hold dear."
https://science.feedback.org/review/claim-about-climate-impacts-of-cows-vs-cars-needs-a-little-explanation-financial-times/,Lacks context,"Financial Times, Barclay's, 2019-02-19",Burping cows are more damaging to the climate than all the cars on this planet.,,"Lacks context: This statement can be accurate or inaccurate depending on the timeframe you select. Just considering the next couple decades, it's true, but in the longer-term it is not.","Because methane is a more potent—but much shorter-lived—greenhouse gas than CO2, the timeframe has to be defined for this statement. Methane lasts about a decade before breaking down, while CO2 can stay in the atmosphere for centuries. This means that cows do have a greater impact in the near-term, but are responsible for a smaller amount of warming in the long-term.",Burping cows are more damaging to the climate than all the cars on this planet.,,"Ilissa Ocko Climate Scientist, Environmental Defense Fund: As written, this claim is missing key information that would make it accurate. It is in need of a timescale over which the climate impacts of “burping cows” are compared to the climate impacts of passenger vehicles. If the statement specified that “burping cows are more damaging to the climate in the near-term (over the following 20 years) than all the cars on this planet,” the statement would be accurate. If we look instead at long-term climate impacts (over the following 100 years) from today’s burping cows versus passenger vehicles, then cars would be twice as “damaging.” The reason that a timescale is needed is because these two sectors emit two different greenhouse gases. “Burping” cows emit methane, whereas passenger vehicles mainly emit carbon dioxide. Although both are greenhouse gases, they have vastly different properties: methane can trap around 100 times more heat than CO2, pound for pound, but because it only lasts for around a decade in the atmosphere, the climate impacts of emissions are short-lived. CO2, on the other hand, can impact the climate for centuries to come, as a large fraction of emissions remain in the atmosphere for thousands of years. Therefore, comparing climate impacts is not straightforward, and a simple metric called Global Warming Potential (GWP) is often employed to convert the methane emissions to the amount of CO2 that would have the same warming impact (using radiative forcing as a proxy) over a specified (and arbitrary) time horizon. If we convert global “burping cow” methane emissions in 2015 (70 MtCH4/yr) to CO2 emissions that would have the same climate impact over the following 20 years (70 MtCH4/yr * CH4 GWP20: 84 = 5,880 MtCO2e20/yr), then burping cows will have a larger impact on climate in the near-term than all the cars worldwide in 2015 (4.6 tCO2/yr/vehicle * 947,080,000 passenger vehicles = 4,360 MtCO2/yr). However, if we instead look at the climate impact of burping cows over the following 100 years (70 MtCH4/yr * CH4 GWP100: 28 = 1,960 MtCO2e100/yr), then the climate impacts of cars worldwide is larger. This is why scientists have suggested always using two time horizons when comparing climate impacts of multiple greenhouse gases – to prevent confusion and clarify climate impacts over all timescales. We can also avoid GWP altogether, and look at the warming impacts over time (in terms of radiative forcing) from present-day emissions of burping cows and passenger vehicles (see figure below). This takes into account the decay rates of methane and CO2 in the atmosphere, and shows that burping cows have a larger climate impact in the near-term but a negligible impact after 50 years. Note that the GWP/CO2e metrics aggregate these warming impacts over 20 and 100 years. Steven Smith Senior Scientist, JGCRI - Pacific Northwest National Laboratory & University of Maryland: The short answer is that this statement looks to be true, but it depends if you’re looking short-term or long-term. This matters quite a bit when comparing a long lived greenhouse gas (CO2) with a short-lived one (CH4): Comparing on a near-term basis (20-year time horizon) CH4 from enteric fermentation has more than double the impact on climate of CO2 from light-duty vehicles. Comparing on a longer-term basis (100-year time horizon), the two are comparable. (Also, the relative importance of cars vs. cows has been increasing over time as vehicle fuel use is increasing faster than livestock populations.) Emissions compared by using 20- and 100-year Global Warming Potentials (GWPs), which integrate the forcing impact from an impulse emission over time (see above figure). Hoesly et al (2018) Historical (1750–2014) anthropogenic emissions of reactive gases and aerosols from the Community Emissions Data System (CEDS), Geoscientific Model Development"
https://science.feedback.org/review/new-york-times-coverage-of-ipcc-report-clearly-presents-conclusions-coral-davenport/,1.5,"The New York Times, by Coral Davenport, on 2018-10-07.",,"""Major Climate Report Describes a Strong Risk of Crisis as Early as 2040""",,,,,"This story inThe New York Times covered the October release of the IPCC’s “Global Warming of 1.5 °C” report. The report, which was requested by governments during the 2015 Paris Agreement negotiations, details the impacts of 1.5°C compared to 2°C and the emissions cuts required to limit warming to either of those levels. Scientists who reviewed the story found that it provided an accurate and detailed summary of the report, though some statements about warming being “worse than previously thought” could have used some clarifying context. This is part of a series of reviews of 2018’s most popular climate stories on social media.See all the scientists’ annotations in context. You can also install the Hypothesis browser extension to read the scientists’ annotations in context.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Andrew King Research fellow, University of Melbourne: The article accurately summarises the IPCC special report on 1.5 °C of global warming. The article represents the key findings of the report and does well at highlighting the impacts of 1.5 °C global warming and discussing the difficulty in limiting warming to this level. Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: This article was based on a UN Report regarding the impacts of climate change for 1.5 degrees C of warming. This was a very comprehensive article, demonstrating the broad range of risks that climate change poses, the scale of the action needed to mitigate climate impacts, as well as the roadblocks to action on climate change. In general, the article did a good job surveying aspects of a large UN report. The article was overwhelmingly based on the science and evidence from the underlying UN report, but would have benefited from additional context for statements that claimed that climate impacts are more dire, are happening more rapidly, or with less global mean warming than previously thought. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Annotations: The statements quoted below are from the article; comments are from the reviewers (and are lightly edited for clarity). paints a far more dire picture of the immediate consequences of climate change than previously thought Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: This statement and similar statements would benefit from specific examples from the report or more context. Although I agree the problem is dire, I’m not sure which aspect of the problem is worse than previously thought. For example, the carbon budget (i.e., how much humans can emit and still warm less than 1.5 degrees C) has expanded from previous estimates. It may be that some impacts will be felt earlier or will be worse than previously estimated—this just wasn’t clearly articulated. Other statements that I thought could have used greater context or examples from the report include the quote by Bill Hare (below), or the statement that “the new report, however, shows that many of those effects will come much sooner, at the 2.7-degree mark.” avoiding the damage requires transforming the world economy at a speed and scale that has “no documented historic precedent.” Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: This is a useful point and comes from The Summary: for Policymakers (C2.1) and is with regard to the economic transition needed to limit the world to 1.5 degrees C of warming (with limited or no “overshoot.”) The report does state that some sectors and technologies have transformed this quickly, but not on the same scale. describes a world of worsening food shortages and wildfires, and a mass die-off of coral reefs as soon as 2040 Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: I thought these were good examples of impacts. I couldn’t find where this exact statement came from, but it seems reasonable given that (to quote the report) “[…] achieving emissions reduction targets consistent with the ambitious goal of 1.5°C of global warming under the Paris Agreement will result in the further loss of 70–90% of reef-building corals compared to today[…]” and that “Global warming is likely to reach 1.5°C between 2030 and 2052 if it continues to increase at the current rate.” And, regarding food security, “Increasing global temperature poses large risks to food security globally and regionally, especially in low-latitude areas (medium confidence) […], with warming of 2°C projected to result in a greater reduction in global crop yields and global nutrition than warming of 1.5°C (high confidence) […], owing to the combined effects of changes in temperature, precipitation and extreme weather events, as well as increasing CO2 concentrations.” But the heads of small island nations, fearful of rising sea levels, had also asked scientists to examine the effects of 2.7 degrees of warming. Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: The UN Report frequently demonstrated that the impacts of climate change (around the world, not just for island nations) are less severe and widespread at 2.7 degrees Fahrenheit compared to 3.6 degrees Fahrenheit. This would have been a useful and easy point to make, given that it was one of the central findings of this report. International Energy Agency, a global analysis organization, “continue to see a role for coal for the foreseeable future.” Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: This statement deserves more scrutiny because it appears that the IEA outlook and the UN Report are considering different scenarios. In the IEA outlook, it is true that coal remains a large component of the global energy system through 2040 under existing and expected policies (“NPS scenario”), but their projection under the “Sustainable Development Scenario,” which takes international climate objectives into account, has coal accounting for 12% of global energy by 2040."
https://science.feedback.org/review/guardian-story-on-climate-impacts-of-diet-gets-mixed-reviews-from-scientists-damian-carrington/,0.2,"The Guardian, by Damian Carrington, on 2018-05-31.",,"""Avoiding meat and dairy is ‘single biggest way’ to reduce your impact on Earth""",,,,,"This article in The Guardiancovers a study published in Science[1] that investigated environmental impacts related to the production of different types of foods in a number of regions around the world, finding that impacts could vary significantly from one place to another. Scientists who reviewed the article gave it varied ratings while focusing on different aspects. Some noted that the headline, in particular, makes a more general claim—that “avoiding meat and dairy is ‘single biggest way’ to reduce your impact on Earth”—that isn’t directly supported by this particular study. These general statements relate to quotes from the researchers behind the study and are explained in less detail and with less context than the contents of the study itself, leaving them potentially misleading. This is part of a series of reviews of 2018’s most popular climate stories on social media.You can read the article here. [1]Poore and Nemecek (2018) Reducing food’s environmental impacts through producers and consumers, Science.GUEST COMMENTS: Stefan Wirsenius Associate Professor, Chalmers University of Technology: The headline of the article is not a fair representation of the research paper, which mainly is about very comprehensive data analysis. But the quote of the lead author supports it. And the article overall gives a balanced and accurate description of the paper. Margaret Gill Professor, University of Aberdeen: The scientific publication referred to in the article was comparing the environmental impact of different foods. The article starts with the following “Avoiding meat and dairy products is the single biggest way to reduce your environmental impact on the planet…” This is wrong on two counts relative to the findings reported in the publication: 1) The publication only considered food—the journalist extrapolated to all human activities, and 2) The publication drew attention to heterogeneity both geographically and between different types of meat—the journalist did not make that distinction, again a gross extrapolation. Martin Heller Research Specialist, University of Michigan: This article relies heavily on statements made by the authors of the covered journal article that are not necessarily supported in the journal article. The statement “avoiding meat and dairy is the single biggest way to reduce your environmental impact on the planet” is not quantified in the journal article, but appears to be an opinion of Joseph Poore. More importantly, the main figure in this story is presented with the wrong units. The data on greenhouse gas emissions per unit of different food is reported in Poore and Nemeck as emissions per “100g of protein” from each food type, a critical distinction. It is also rather misleading (and confusing) to present the 90th percentile value as a datapoint and use that 90th percentile value as the reference (i.e., the comparison used in the figure title). Poore and Nemeck report means for all of these values: this would be a much more appropriate value to be reporting here. Hugo Valin Research Scholar, The International Institute for Applied Systems Analysis: The article provides a rigorous description of the Science article on the impact of different food products and the results of different changes in consumption patterns. The strong value added of the Science article is rather in the large dataset collected and the illustration of the heterogeneity in the level of impacts, as the average adverse impacts of food on the environment is documented elsewhere. As described by the article, this heterogeneity also means that becoming vegan is not the only option to have impact on the system. From this point of view, the title of the article is slightly misleading, as some big impacts could also be achieved by consuming products produced more efficiently. However, we illustrated with coauthors in another paper[1] that average EU diet impact on climate was equivalent to driving 6,000 km in a single passenger car. So indeed, for many people, decreasing the diet impact is among their biggest lever of action (after having an extra kid, as provocatively reminded by this peer-review study[2] published in Environmental Research Letters). [1] Sandström et al (2018)The role of trade in the greenhouse gas footprints of EU diets, Global Food Security [2] Wynes and Nicholas (2017)The climate mitigation gap: education and government recommendations miss the most effective individual actions, Environmental Research Letters Harry Aiking Associate Professor, Vrije Universiteit Amsterdam: The word “Avoiding” in title and text is overly strong and should have been “Reducing”. Adopting a vegan diet is not necessary, but a reduction to having meat 1-2 times a week and dairy 3-4 times a week would suffice. In fact, flexitarian diets utilize natural resources much more efficiently than vegan diets[1]. In the article, Peter Alexander is quoted saying something to the same effect. The underlying Science paper by Poore & Nemecek is using life cycle assessment. Life cycle assessment is an inherently arbitrary bookkeeping method and potentially misleading. Its caveats take a lifetime to fathom and some can and should be made explicit to lay people. To mention just one example out of many, expressing units per kg live weight, dry weight, or protein (or even cost, using economic allocation) makes a tremendous difference. As an illustration, try to compare cheese and milk. Such cautionary advice is lacking entirely. [1] Nonhebel (2004) On resource use in food production systems: The value of livestock as ‘rest-stream upgrading system’, Ecological Economics Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time."
https://science.feedback.org/review/story-on-congressmans-incorrect-claims-about-sea-level-rise-could-have-corrected-them-more-explicitly/,-0.3,"E&E News, Science Magazine, by Scott Waldman, on 2018-05-17.",,"""Republican lawmaker: Rocks tumbling into ocean causing sea level rise""",,,,,"This article in the news section ofScience—syndicated from E&E News—covers a hearing of theU.S. House of Representatives Science, Space, and Technology Committee. During the hearing, some committee members made a number of incorrect claims about climate change and sea level rise. Most notably, Representative Mo Brooks claimed that the erosion of coastal rock and sediment could be the real cause of sea level rise. The article focuses on creating an account of statements made by those present at the hearing. Scientists who reviewed this article provided varying ratings, as the article generally noted that these claims were false but did not always explicitly explain the actual state of scientific knowledge. For example, providing references to published research directly contradicting these claims could have helped readers ascertain the truth. This is part of a series of reviews of 2018’s most popular climate stories on social media.See all the scientists’ annotations in context. You can also install the Hypothesis browser extension to read the scientists’ annotations in context.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Andrew Shepherd Professor, University of Leeds: The article itself is I believe a well-intentioned attempt to report on what seems to have been a rather chaotic committee meeting; although the meeting topic was intended to be on technologies to mitigate climate change, the discussion concentrated on basic climate change principles and conjecture which the witnesses could reasonably have not expected. Although the article is good in places, I have graded it as very low credibility because there are several committee member statements that are false and not adequately corrected in the printed article. 1) The article opens with three apparently controversial statements attributed to a committee member that are not immediately corrected with facts, when they could have been: the Earth is warming. Sea level rise due to coastal erosion is insignificant in comparison to other known sources and sinks. The Antarctic ice sheet is not growing. 2) A committee member objects to the suggestion that global warming is man-made, stating that “basically we should all be open to different points of view”. This statement should have been rebutted, as the evidence to the contrary is overwhelming and it is not reasonable to assert that objection to scientific fact or consensus amounts to an alternative point of view. 3) A committee member suggests that land erosion is causing sea level rise: while the witness (Duffy) responds that he is “pretty sure” this is not the case, a factual correction could have been offered to shoot the suggestion down. 4) A committee member suggests that “there are plenty of studies that have come that show with respect to Antarctica that the total ice sheet, particularly that above land, is increasing, not decreasing.” As leader of the international community effort responsible for charting polar ice sheet contributions to sea level rise, I can assure you that this statement is false. There is in fact only one study that reports growth of the Antarctic ice sheet, against all others (dozens) that report that it has lost ice. And the one study[1] that reported mass gains was effectively rebutted by a separate study[2]. For a summary of ice sheet mass balance data, see Figure 1 here. [1]-Zwally et al (2015) Mass gains of the Antarctic ice sheet exceed losses, Journal of Glaciology [2]-Scambos and Shuman (2016) Comment on ‘Mass gains of the Antarctic ice sheet exceed losses’ by H. J. Zwally and others, Journal of Glaciology Benjamin Horton Professor, Earth Observatory of Singapore: The article was an appropriate discussion of some very misleading and ill-informed comments by Republicans on the U.S. House of Representatives Science, Space and Technology Committee. Keven Roy Research Fellow, Nanyang Technological University: This article is mostly a descriptive depiction of an exchange between some members of the Space, Science and Technology Committee and a climate scientist. The comments from the members of the Committee suffer from severe inaccuracies and misconceptions, and citations of the invited climate scientist mostly address those issues. In general, the views that go against our understanding of the climate change process are underlined and presented as such by the author, but rarely supported by statements or explanations that go beyond the immediate replies from the invited climate scientist. Some of the inaccurate statements quoted in the text are thus left with an incomplete challenge. In particular, the concluding statement should have been challenged. The explanations sometimes suffer from imprecise language (land/sea ice, sea level rise timescales) but they are usually adequate. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Annotations: The statements quoted below are from the article; comments are from the reviewers (and are lightly edited for clarity). “I’m being extremely practical — if we let the planet warm 2 or 3 degrees, we will have tens of meters of sea-level rise, and the community where I live will essentially cease to exist.” Keven Roy Research Fellow, Nanyang Technological University: Sea level rise is undoubtedly one of the most severe consequences of anthropogenic climate change, but this statement should discuss timescales and present a revised amplitude. In fact, over the 21st century, estimates of global mean sea level rise are rather in the 1-2 m range[1]. Considering the global mean sea level rise commitment induced by these conditions up to 2300 leads to estimates reaching several meters[1]. Such a change in mean sea level will significantly impact coastal communities around the world. During episodes in the geological past with similar temperature and CO2 conditions, like the mid-Pliocene around 3 million years ago, sea level may have reached significantly higher values (raising questions about the long-term equilibrium of sea level), but constraining precisely this quantity using the geological record remains challenging. [1] Horton et al (2018) Mapping Sea-Level Change in Time, Space, and Probability, Annual Review: of Environment and Resources “I don’t think anybody disputes that the Earth is getting warmer; I think what’s not clear is the exact amount of who caused what, and getting to that is, I think, where we’re trying to go with this committee.” Keven Roy Research Fellow, Nanyang Technological University: The various contributions to recent climate change have been studied extensively by the scientific community, and there is ample evidence of the human influence on the recent climate. The IPCC has identified human activity as the dominant cause of the observed warming since the mid-20th century with an extremely high degree of confidence. IPCC (2013) Summary: for Policymakers. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change At one point, Smith showed a slide of two charts that he said demonstrated how the rate of sea-level rise does not equal the sharp spike in the consumption of fossil fuels. Thomas Frederikse Postdoctoral researcher, Jet Propulsion Laboratory/California Institute of Technology: This statement is blatantly false: sea-level rise in the 20th century is faster than any time during the last 3000 years[1], while the present-day rate is already three times faster than the 20th-century rate[2]. [1] Kopp et al (2016). Temperature-Driven Global Sea-Level Variability in the Common Era,PNAS [2] Dangendorf et al (2017) Reassessment of 20th Century Global Mean Sea Level Rise, PNAS Duffy pointed out that his chart was from a single tide gauge station, near San Francisco, and that sea levels rise at different rates around the world Thomas Frederikse Postdoctoral researcher, Jet Propulsion Laboratory/California Institute of Technology: This is an important and true statement: sea-level changes differ from place to place. Furthermore, single records often contain a lot of internal variability, which makes it difficult to distinguish anthropogenic changes from the internal variability. Nevertheless, the San Francisco tide gauge shows a sea-level acceleration that is in line with the global-mean value. Hogarth (2014) Preliminary Analysis of Acceleration of Sea Level Rise through the Twentieth Century Using Extended Tide Gauge Data Sets, Journal of Geophysical Research: Oceans He said the California coastline and the White Cliffs of Dover tumble into the sea every year, and that contributes to sea-level rise Thomas Frederikse Postdoctoral researcher, Jet Propulsion Laboratory/California Institute of Technology: Although this effect is not zero, about 1,000 cubic kilometers (i.e. 1,000 rocks of a kilometer long, a kilometer wide, and a kilometer tall) of Dover cliffs must tumble into the ocean to explain the present-day rate of sea-level change. This is many orders of magnitude larger than the ongoing erosion rate. He also said that silt washing into the ocean from the world’s major rivers, including the Mississippi, the Amazon and the Nile, is contributing to sea-level rise. Thomas Frederikse Postdoctoral researcher, Jet Propulsion Laboratory/California Institute of Technology: Sediment deposition has been acknowledged by scientists, but again, this effect is many orders of magnitudes too small to explain the ongoing rate of sea-level rise. Duffy responded: “I’m pretty sure that on human time scales, those are minuscule effects.” Thomas Frederikse Postdoctoral researcher, Jet Propulsion Laboratory/California Institute of Technology: Duffy is right: these effects are minuscule compared to ice-mass loss and thermal expansion of the oceans, both of which are directly measured, and explain the observed present-day sea-level rise. WCRP Global Sea Level Budget Group (2018) Global Sea-Level Budget 1993–Present, Earth System Science Data Brooks added that Antarctic ice is growing. Thomas Frederikse Postdoctoral researcher, Jet Propulsion Laboratory/California Institute of Technology: While the extent of Antarctic sea ice is slightly growing, this growth does not affect sea level, because of Archimedes’ law. The land ice of the Antarctic Ice Sheet is shrinking at an accelerating pace, which does result in sea-level rise. The IMBIE team (2018) Mass Balance of the Antarctic Ice Sheet from 1992 to 2017, Nature Bamber (2018) The Land Ice Contribution to Sea Level during the Satellite Era, Environmental Research Letters “Well, I’ve got a NASA base in my district, and apparently, they’re telling you one thing and me a different thing,” Brooks said. “But there are plenty of studies that have come that show with respect to Antarctica that the total ice sheet, particularly that above land, is increasing, not decreasing. Thomas Frederikse Postdoctoral researcher, Jet Propulsion Laboratory/California Institute of Technology: The increasing rate of Antarctic mass loss has been confirmed by multiple independent observation systems. “What do you say to people who theorize that the Earth as it continues to warm is returning to its normal temperature?” Thomas Frederikse Postdoctoral researcher, Jet Propulsion Laboratory/California Institute of Technology: This is a fallacy, which has been correctly rebutted by Duffy. What matters is that a large increase in global temperatures is problematic for us humans, who have built a civilisation in a relatively stable climate, and which we are now perturbing far outside this stable range."
https://science.feedback.org/review/bbc-article-on-ipcc-report-is-mostly-accurate-but-could-use-some-clarification/,1.0,"BBC, by Matt McGrath, on 2018-10-08.",,"""Final call to save the world from 'climate catastrophe'""",,,,,"This BBC story covered the October release of the IPCC’s “Global Warming of 1.5 °C” report. The report, which was requested by governments during the 2015 Paris Agreement negotiations, details the impacts of 1.5°C compared to 2°C and the emissions cuts required to limit warming to either of those levels. Scientists who reviewed the story found that its summary of the report is generally accurate. However, some details could have been explained to give readers a clearer understanding. This is part of a series of reviews of 2018’s most popular climate stories on social media.Read the article here.GUEST COMMENTS: Sally Brown Senior Research Fellow, The University of Southampton: Whilst not being able to check all facts in detail, this article provides a well-rounded view of the science using common questions and puts it in perspective, using graphics in an easy to understand way. Quotes are from a mix of scientists and NGOs, so provides a balanced perspective from those at the meeting. There is global representation but also a discussion of individual actions, so the article reaches to different audiences. REVIEWERS’ OVERALL FEEDBACK: Joeri Rogelj Professor, Centre for Environmental Policy at Imperial College London: Scientifically, the article is overall correct, but it is in cases inaccurate in its description of certain aspects of the IPCC. For example, the IPCC does not conduct research, but assesses the available scientific evidence. Neither Dr. Debrah Roberts nor Prof. Jim Skea are a co-chair of the IPCC (no such role exists)—they are co-chairs of two of the three Working Groups of the IPCC. (In this case, Working Group 2 on impacts and Working Group 3 on mitigation and solutions, respectively.) The article also provides statements without context, despite this being essential for their interpretation. For example, the annual investment needs in the energy sector for achieving a 1.5°C compatible pathway are indeed roughly 2.5% of global GDP, but this compares to about 1.8% of global GDP in a world in which we put the world on track for 4°C by the end of the century. The difference in investments is also roughly an order of magnitude smaller than the annual percentage of GDP we spend on energy. The absence of this context makes it impossible to judge whether the editor’s value judgment that limiting warming to 1.5°C would be “hugely expensive”. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time."
https://science.feedback.org/review/cnn-accurately-covers-latest-ipcc-report-brandon-miller/,1.5,"CNN, by Brandon Miller, on 2018-10-08.",,"""Planet has only until 2030 to stem catastrophic climate change, experts warn""",,,,,"This CNN story covered the October release of the IPCC’s “Global Warming of 1.5 °C” report. The report, which was requested by governments during the 2015 Paris Agreement negotiations, details the impacts of 1.5°C compared to 2°C and the emissions cuts required to limit warming to either of those levels. Scientists who reviewed the story found that it conveyed the information in the report without any errors, and included comments by scientists to summarize the report’s implications. This is part of a series of reviews of 2018’s most popular climate stories on social media.Read the article here.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Sara Vicca Postdoctoral research fellow, University of Antwerp: Very accurate summary of some key aspects of the IPCC special report on 1.5 °C. Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: The article has nothing contentious in it, as it merely restates and paraphrases the content of the IPCC report, with added quotes from scientists and political advocates. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time."
https://science.feedback.org/review/usa-today-story-updates-readers-on-trend-in-monthly-global-temperatures-doyle-rice/,2,"USA Today, by Doyle Rice, on 2018-05-17.",,"""Earth just had its 400th straight warmer-than-average month thanks to global warming""",,,,,"This article in USA Todaynotes that April 2018 was the 400th straight month that global temperatures were above the 20th century average, and correctly identifies human activities as the cause of this trend. It also highlights several regions that saw record-high April temperatures. Scientists who reviewed the article found that it accurately described these facts and clearly explained how above-average months are calculated. This is part of a series of reviews of 2018’s most popular climate stories on social media.See all the scientists’ annotations in context. You can also install the Hypothesis browser extension to read the scientists’ annotations in context.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Andrew King Research fellow, University of Melbourne: This article does a good job of summarising the extended run of global-average temperatures above the 20th century average. The article correctly attributes the cause of this extended run of global warmth to human-caused greenhouse gas emissions. Peter Thorne Professor, Maynooth University: The piece accurately reports the surface temperature record warming of recent decades and joins the dots appropriately to the underlying cause of human emissions. It appropriately draws the distinction between regional/national records and the global mean behaviour. The included quotes are to authoritative sources. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Annotations: The statements quoted below are from the article; comments are from the reviewers (and are lightly edited for clarity). Climate scientists use the 20th-century average as a benchmark for global temperature measurements. That’s because it’s fixed in time, allowing for consistent “goal posts” when reviewing climate data. It’s also a sufficiently long period to include several cycles of climate variability. Andrew King Research fellow, University of Melbourne: This is an excellent summary of why the 20th century average is a suitable baseline. NOAA’s analysis found last month was the 3rd-warmest April on record globally. The unusual heat was most noteworthy in Europe, which had its warmest April on record, and Australia, which had its second-warmest. Portions of Asia also experienced some extreme heat: In southern Pakistan, the town of Nawabshah soared to a scalding 122.4 degrees on April 30, which may have been the warmest April temperature on record for the globe, according to Meteo France. Argentina also had its warmest April since national records began there in 1961.North America was the one part of the world that didn’t get in on the heat parade. Last month, the average U.S. temperature was 48.9 degrees, 2.2 degrees below average, “making it the 13th-coldest April on record and the coldest since 1997,” NOAA said.Andrew King Research fellow, University of Melbourne: The article points to several regional records or near-records for heat extremes that occurred near the start of the year. The increase in the number of warm temperature records has been documented for many regions of the world (e.g. the US1) and can be attributed to human-caused climate change2. 1-Meehl et al (2009)Relative increase of record high maximum temperatures compared to record low minimum temperatures in the U.S., Geophysical Research Letters 2-King (2017)Attributing Changing Rates of Temperature Record Breaking to Anthropogenic Influences, Earth’s Future For the year-to-date, the Earth is seeing its 5th-warmest start to the year. Andrew King Research fellow, University of Melbourne: As of November, according to the NASA GISS record, 2018 is likely to be the 4th warmest year on record."
https://science.feedback.org/review/washington-post-article-accurately-discusses-warm-arctic-weather-event-jason-samenow/,2,"The Washington Post, by Jason Samenow, on 2018-02-26.",,"""North Pole surges above freezing in the dead of winter, stunning scientists""",,,,,"This article in The Washington Post describes a pattern of unusually warm weather in February 2018, during which the North Pole saw above-freezing air temperatures. The article also places this event in context of past weather variability, explaining that there is an increasing trend of warm temperature extremes. Scientists who reviewed the story found that it covered both of these points accurately. The trends are correctly identified without exaggeration, giving readers an accurate understanding of what the data show. This is part of a series of reviews of 2018’s most popular climate stories on social media.You can read the article here. REVIEWERS’ OVERALL FEEDBACK: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Robert Graham Postdoc, Norwegian Polar Institute: The article presents and discusses this weather event in the article accurately, and provides figures to show this. The journalist has contacted several scientists from different research institutes to comment on the event and quotes these scientists accurately, with references. I do not identify anything in the article that is incorrect/flawed. Kelly McCusker Research Associate, Rhodium Group and Climate Impact Lab: This article accurately describes the Arctic warming event and associated surprise by scientists, includes multiple explanations for possible causes, and does not overstate any connections to climate change, pointing out that more data is needed to know if these above-freezing events will be a new Arctic normal. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time."
https://science.feedback.org/review/friends-of-science-video-promoted-by-youtube-presents-long-list-of-climate-myths-steve-goreham/,-2,"YouTube, Friends of Science, by Steve Goreham, on 2017-07-01.",,"""Climate Science and the Myths of Renewable Energy - FOS Steve Goreham""",,,,,"This video of a talk by author and speaker Steve Goreham, posted by the YouTube channel “Friends of Science” has been viewed over 250,000 times and has been widely promoted by Youtube recently. In it, Goreham claims that climate change is not dangerous, and is not caused by humans. Scientists who reviewed the talk found that it was comprised of a litany of common myths about climate science. Goreham misrepresents global temperature data, the physics of the greenhouse effect, and the factors controlling sea level rise, among many other things, as explained below by scientists. UPDATE: As of July 11, 2019 the video has amassed more than 450,000 views on Youtube and keeps being shared regularly on Facebook. This illustrates that online misinformation can generate long-lasting damages.See all the scientists’ annotations in context. You can also install the Hypothesis browser extension to read the scientists’ annotations in context. REVIEWERS’ OVERALL FEEDBACK: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Stefan Rahmstorf Professor, Potsdam University: The video presents a litany of the usual climate denier talking points, none of which hold any water. It is full of outright false claims and does not even shy away from presenting a fake TIME magazine cover that supposedly warned of an ice age. “Friends of Science” is an advocacy group “largely funded by the fossil fuel industry”, according to Wikipedia. Already its name is intended to mislead. Twila Moon Research Scientist, University of Colorado, Boulder: The information in this video is consistently false, using some correct ideas (e.g. Greenland is thinning at edges and thickening in the center) to build up incorrect explanations (e.g. so overall Greenland is not changing much). The video builds scientifically incorrect understandings for a wide variety of topics. Patrick Brown Assistant Professor, San Jose State University: The video is of very low scientific quality. It stitches together dozens of unoriginal myths about climate science that have been debunked over and over again. Mark Richardson Research Associate, Colorado State University/NASA JPL: This video is shameful and full of well-known tricks that deceive people about global warming. Almost every statement is false or misleading. Radiometer measurements of Earth’s atmosphere confirm CO2‘s heating effect just as expected, and other instruments rule out the Sun or volcanoes. There are specific “fingerprints” in patterns of warming that match CO2 caused warming and we have measured increasing water vapour in the air in response, just as predicted decades ago. This video is an embarrassment. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Takeaways: The statements quoted below are from Goreham’s video; comments are from the reviewers (and are lightly edited for clarity). 1. Greenhouse gas emissions are causing climate change by measurably strengthening the greenhouse effect in line with the expectations of physics and chemistry. “There is no empirical evidence that increasing greenhouse gases are the primary cause of Global Warming” Patrick Brown Assistant Professor, San Jose State University: This is not true. The primary empirical evidence that greenhouse gasses cause global warming is the absorption (as a function of wavelength of radiation) of gasses like CO2, CH4 and N2O. This was discovered in 1859 by John Tyndall and has become a part of fundamental physics. Anyone can check this empirical relationship at any time with an absorption spectroscopy device. The empirical evidence that increases in greenhouse gas concentrations (from fossil fuel burning) are the primary cause of century-scale warming is that observed global temperatures have risen in line with what would be expected from the observed increase in greenhouse gas concentrations and observations of natural drivers of climate change (e.g. solar output and volcanic eruptions) indicate that natural drivers are not causing warming. Anthony Walker Research Staff, Oak Ridge National Laboratory: The initial claim that there is no empirical evidence is unfalsifiable. What evidence would be required? A manipulation of multiple identical planets, one group with fossil fuel burning etc, the other group with no humans. There is empirical evidence that CO2 is increasing, there is empirical evidence that this is from fossil fuel burning, there is evidence that this is altering the radiative balance of the planet, there is empirical evidence that global temperatures are increasing. The IPCC reports have all the latest references for these various evidence streams. Rasmus Benestad Senior scientist, The Norwegian Meteorological institute: The greenhouse effect exists on other planets in the Solar System and explains why planets like Venus have such a hot surface. The big picture is explained in the paper “A mental picture of the greenhouse effect”*, which also presents some empirical evidence contrary to the false statement in the video. The challenge, rather, would be to explain why increased levels of greenhouse gases potentially would not influence the greenhouse effect. (It does). Benestad (2016) A mental picture of the greenhouse effect, Theoretical and Applied Climatology “Today climate scientists are obsessed with the level of carbon dioxide in the atmosphere, a very very small part of the overall picture. Carbon dioxide is a trace gas.” Patrick Brown Assistant Professor, San Jose State University: The small percent of CO2 by volume in the atmosphere (what makes it a trace gas) is utterly irrelevant in terms of its radiative properties and thus its effect on global temperature. Climate scientists pay special attention to CO2 because its radiative properties have allowed it to be the dominant cause of warming over the past century. Mark Richardson Research Associate, Colorado State University/NASA JPL: When the speaker is willing to inject such a “trace amount” of ebola or ricin into their own body I’ll believe that they were being serious with this argument. “But what is nature’s most abundant greenhouse gas? Water vapor. It’s not carbon dioxide, it’s not methane… Scientists estimate that somewhere between 75% and 90% of Earth greenhouse effect is caused by water vapor in clouds.” Patrick Brown Assistant Professor, San Jose State University: Ironically, the paper that he is citing here is called “Atmospheric CO2: Principal Control Knob Governing Earth’s Temperature”[1]. The abstract explains why CO2 is the control knob even if it does not make up a majority of the current greenhouse effect: “Ample physical evidence shows that carbon dioxide (CO2) is the single most important climate-relevant greenhouse gas in Earth’s atmosphere. This is because CO2, like ozone, N2O, CH4, and chlorofluorocarbons, does not condense and precipitate from the atmosphere at current climate temperatures, whereas water vapor can and does. Noncondensing greenhouse gases, which account for 25% of the total terrestrial greenhouse effect, thus serve to provide the stable temperature structure that sustains the current levels of atmospheric water vapor and clouds via feedback processes that account for the remaining 75% of the greenhouse effect. Without the radiative forcing supplied by CO2 and the other noncondensing greenhouse gases, the terrestrial greenhouse would collapse, plunging the global climate into an icebound Earth state.” [1] Lacis et al (2010) Atmospheric CO2: Principal Control Knob Governing Earth’s Temperature, Science Mark Richardson Research Associate, Colorado State University/NASA JPL: This calculation estimates each fraction now. If you took the CO2 out and we lost 20 % of the greenhouse effect, Earth would cool down and lots of the vapour would rain out. The amount of water vapour responds to temperature and circulation, nowadays CO2 is the driver. “Every day, nature puts twenty times as much carbon dioxide into the atmosphere as all of Earth industries. That means that humans are responsible for about one or two parts per hundred over its greenhouse effect.” Stefan Rahmstorf Professor, Potsdam University: A classic misleading climate skeptic talking point which confuses the natural zero-sum turnover, which does not add anything to the atmosphere, with the net addition by human activities. A few scientifically uncontroversial facts: 1) Since the beginning of industrialization, the CO2 concentration has risen from 280 ppm (the value of the previous millennia of the Holocene) to now 405 ppm. 2) This increase by 45 percent (or 125 ppm) is completely caused by humans. 3) The CO2 concentration is thus now already higher than it has been for several million years. (Full explanation here.) Patrick Brown Assistant Professor, San Jose State University: This is wrong. Nature puts in more CO2 than industry but nature also takes out exactly what it puts in (on century timescales). This means that nature puts essentially zero NET CO2 into the atmosphere. The rise in atmospheric CO2 since the Industrial Revolution has been entirely driven by human burning of fossil fuels. Rasmus Benestad Senior scientist, The Norwegian Meteorological institute: The important point is that the net effect to the CO2 exchanged between different parts leads to a rise in the CO2-concentration, which now has passed 400 parts per million. There is no doubt that the increase in the concentration is due to burning of fossil fuels—it’s easy to calculate based on the amount of oil, gas and coal that is burned, and the chemistry. A comparison between the sizes of the various fluxes between the different parts clutters the discussion. Furthermore, water vapour (H2O) has a short life time in the atmosphere compared to CO2. It rains out after a few days whereas CO2-levels stay for centuries. “So it’s clear now we’re not seeing dangerous global warming, and the climate models are wrong.” Mark Richardson Research Associate, Colorado State University/NASA JPL: We have done a bunch of comparisons with models and observations. The surface observations are more reliable because there are so many of them, and satellite infrared (think Predator vision) backs them up. We checked from the 1860s to today and it’s remarkable how well the observed warming matches the modelled warming*. Richardson et al (2016) Reconciled climate response estimates from climate models and the energy budget of Earth, Nature Climate Change Hausfather et al (2017) Assessing recent warming using instrumentally homogeneous sea surface temperature records, Science Patrick Brown Assistant Professor, San Jose State University: This graph has a lot of problems (as explained here). But one problem is that humans and ecosystems live on the Earth’s surface and this is data for the mid-atmosphere. Observations of surface temperature through 2018 are more or less in the center of the climate model predicted range. Rasmus Benestad Senior scientist, The Norwegian Meteorological institute: The claim is false: the graph shows a misguided comparison between (1) the average of climate model simulations for a part of the upper atmosphere that is strongly affected by the clouds and the Hadley cell in the Tropics, (2) temperature derived from satellite measurements, and (3) balloon data. This exercise fails on statistical terms, since the comparison should be carried out between all individual climate models (to show the their spread)—one cannot expect the average value to match the one that is measured, just as one does not expect that the temperature in Washington always to be the same as the mean temperature in Washington. There are also issues with using the satellite data as a reference, since satellites do not measure temperature directly. They measure light and make use of algorithms based on the same principles, as those used in the climate models, to estimate the temperatures. Hence, the satellite data are also model results, and the comparison between the two is like comparing different models. The satellite data data have some issues regarding how different records are stitched together from different missions and how the signal is affected by clouds and other factors. The balloon (radiosondes) do not give a good representation over the upper air, as there are few of them. More information. [Read more about this incorrect claim that climate models have overestimated recent warming] “If we double atmospheric carbon dioxide[…] we’d only raise global surface temperatures by about a degree Celsius.” Mark Richardson Research Associate, Colorado State University/NASA JPL: More like 3 degrees, but only being 200% wrong is pretty good by the standards of this talk. Patrick Brown Assistant Professor, San Jose State University: Dozens of studies over the past several decades have calculated this number from every perspective that scientists can imagine the best estimate continues to fall around 3 degrees Celsius, with a vanishingly small chance that it could be as low as 1 degree Celsius. Figure – Compilation of climate sensitivity studies by Carbon Brief. “The idea that the much smaller carbon dioxide cycle is now controlling the water cycle is not very likely.” Rasmus Benestad Senior scientist, The Norwegian Meteorological institute: This statement does not appreciate our current understanding. To understand this, one needs to model the climate and how it matters for the atmospheric circulation and the planetary energy balance. In some regions, it gets drier (typically the subtropics) and in others there is increasing precipitation (typically the mid-latitudes). There are some indications that the rain on a global scale is getting more intense and concentrated over a diminishing area*. Benestad (2018) Implications of a decrease in the precipitation area for the past and the future, Environmental Research Letters “So the bottom line of all this is that climate change is natural, not man-made. I don’t have a chance to go into a lot of the details, but it’s due to natural cycles of Earth that are probably driven by the Sun. Man-made greenhouse gases play only an insignificant role.” Rasmus Benestad Senior scientist, The Norwegian Meteorological institute: We know for sure that climate change is not caused by changes in the Sun because there have been no long-term trend in the solar behavior that can explain the global warming. Patrick Brown Assistant Professor, San Jose State University: The best estimate that we have is that 100% of the warming since the mid 20th century is human-caused [see e.g. this reviewor this article]. This is because the natural causes of climate change that are active on these timescales should have either caused cooling or no change in temperature without human influence. Mark Richardson Research Associate, Colorado State University/NASA JPL: If anything, the Sun has cooled in recent decades. That was reported in 2007[1]. And new satellite data says it has stayed cooler. [1] Lockwood and Fröhlich (2007) Recent oppositely directed trends in solar climate forcings and the global mean surface air temperature, Philosophical Transactions of the Royal Society A “Climate scientists are telling us it’s likely we’re going to be in for a period of cooling.” Stefan Rahmstorf Professor, Potsdam University: Climate scientists are telling us no such thing. Questionable “climate skeptics” are again and again predicting a coming cooling, which then fails to materialise. Rasmus Benestad Senior scientist, The Norwegian Meteorological institute: No. The effect of a cooler Sun is smaller than the increased forcing from higher levels of greenhouse gases. 2.Scientists use records of past climate to build the context that helps us understand that humans are currently causing dangerous climate change. “Of course climate change is real, climate has been changing for all of Earth’s history” Stefan Rahmstorf Professor, Potsdam University: I recommend Prof. Katharine Hayhoe’s nice short summary: How do climate scientists know that climate change is real and caused by humans? Patrick Brown Assistant Professor, San Jose State University: All climate scientists agree with this statement. The primary concern about contemporary global warming is that the change in global climate is thought to be occurring roughly 10X faster than previous major climate changes (with the exception being the decades after major asteroid/comet impacts). Mark Richardson Research Associate, Colorado State University/NASA JPL: And if you think that this somehow means that current global warming is not caused by humans, I guess you agree with this: Barcelona scored goals all through their history, even before Lionel Messi was born! Therefore Lionel Messi can’t score goals. (Or for American readers: the Rams scored touchdowns all through their history even before they signed Todd Gurley. Therefore Todd Gurley can’t score touchdowns.) “temperatures rise and they fall, and they rise and they fall… and for the last 400 years we’ve had a gentle warming as we’ve been coming out of the little ice age.” Patrick Brown Assistant Professor, San Jose State University: Changes in global temperature require global energy imbalances – they don’t happen by magic. We understand a lot about why global energy imbalances have occurred over the past 10,000 years (it mostly has to due with changes in solar output and volcanic aerosol concentrations). We also understand that the current large energy imbalance that is causing rapid century-scale warming has come about because of persistently rising atmospheric greenhouse gas concentrations from fossil fuel burning. “the record refers to the thermometer record, which is only a 130 years long…That is very misleading: that ignores all the period over the past 10,000 years when it was warmer than it is today” Patrick Brown Assistant Professor, San Jose State University: This graph does not actually show the “modern warm period” since it ends before 1950. Also, it is only for Greenland (not a global record). Global reconstructions of temperature over the past 10,000 years indicate that we are experiencing much more rapid warming than previous periods and are currently exiting the range of temperatures experienced over the past 10,000 years. “Where we have a glacier today, a thousand years ago we had a forest. It was warmer a thousand years ago than it is today.” Rasmus Benestad Senior scientist, The Norwegian Meteorological institute: The statement “it was warmer a thousand years ago than it is today” or 5,000 years ago has no good evidence—the discussion about Mendenhall glacier and how it reached a forest has a local perspective and is more complicated. Glaciers respond to not just temperature, but also precipitation and the wind directions. It shows that there are local/regional variations in climate and that the climate is sensitive to changing forcings/factors. Anthony Walker Research Staff, Oak Ridge National Laboratory: I can find no evidence of the Bradshaw reference he’s referring to. The closest I can come to is that he is referencing a photo in an online article in Live Science. That’s not to say that it’s not in the literature somewhere, just that the reference he’s using is not from primary literature. “Temperatures cooled from about 1940 to 1975, and then they rose from about ’75 to about 2005 or so, and since then they’ve been flat or cooling.” Rasmus Benestad Senior scientist, The Norwegian Meteorological institute: The temperature curve from the amateur website Climate4You.org is misleading as it hides the time scales important for the case of climate change. Rather than showing a subselection of the monthly mean HadCRUT3 data, a better choice would be to show the annual mean values of the HadCRUT4 for the entire common period—also up to 2018. Also, there has not been any recent cooling. “[The] front cover of Time and Newsweek, and many professors were teaching that we had to prepare for the coming ice age.” Stefan Rahmstorf Professor, Potsdam University: There never was such a TIME front cover. The picture shown is a well-known fake. Patrick Brown Assistant Professor, San Jose State University: From the 1940s to the 1970s, the global surface temperature decreased very slightly. This probably occurred because over that time period the cooling effect from human produced aerosols was slightly larger than the warming effect from human produced greenhouse gasses. A minority of scientists predicted that the cooling effect from increasing aerosols would continue to outweigh the warming effect from increasing greenhouse gasses and that the climate would continue to cool. This idea received some public attention when Time magazine published an article titled “Another Ice Age?” in 1974 (the cover of Time shown in the video is a fake). Regardless, this article did not represent the views of the majority of the scientific literature at the time1. For example, a 1975 paper, published by Wallace Broecker2 contained the following abstract: “If man-made dust is unimportant as a major cause of climatic change, then a strong case can be made that the present cooling trend will, within a decade or so, give way to a pronounced warming induced by carbon dioxide. By analogy with similar events in the past, the natural climatic cooling which, since 1940, has more than compensated for the carbon dioxide effect, will soon bottom out. Once this happens, the exponential rise in the atmospheric carbon dioxide content will tend to become a significant factor and by early in the next century will have driven the mean planetary temperature beyond the limits experienced during the last 1000 years.” This prediction turned out to be remarkably accurate. Peterson et al (2008) The myth of the 1970s global cooling scientific consensus, Bulletin of the American Meteorological Society Broecker (1975) Climatic Change: Are we on the brink of a pronounced global warming?, Science“So now we’re able to explain from natural factors how we’ve had the 20th Century warming. And it’s the combination of two factors: The first, we’re having a long-term, gentle temperature rise as we’ve emerged from the Little Ice Age[…] And then on top of that, we have the variations in temperature cycles of the oceans Stefan Rahmstorf Professor, Potsdam University: This is a false statement—no scientific study can explain modern warming in this way. “Emerging from the little ice age” is not a physical mechanism or explanation. Anthony Walker Research Staff, Oak Ridge National Laboratory: A recent paper demonstrates that global temperatures are hotter now than in the last 11,000 years[1]. His argument that there have been hot and cold cycles, including medieval warm period and little ice age, are likely based on regional temperature records / reconstructions rather than global temperature records / reconstructions. [1] Marsicek et al (2018) Reconciling divergent trends and millennial variations in Holocene temperatures, Nature 3. Sea level rise is caused primarily by the measured loss of glacial land ice and the expansion of seawater as it warms. “This is the third station at the South Pole, I’m sure some of you know what happened to the other two stations[…] They were buried by snow.” Rasmus Benestad Senior scientist, The Norwegian Meteorological institute: The amount of snowfall increases with temperature as long as the temperature is below 0°C—above this temperature, it turns into rain. The Antarctica is still well below the freezing point, and increased temperatures are expected to give increased snowfall because the air is capable of holding more moisture. Likewise, the sea-ice around the Antarctica form during winter, when the temperatures still are below freezing, and are therefore not a good indicator for the global warming. The sea-ice extent is more strongly influenced by the salinity of the surface water, ocean currents and winds. The Antarctic is a continent surrounded by oceans, and there is little sea-ice in summer when the temperatures are higher. The Arctic, on the other hand, is an ocean surrounded by continents, and has sea-ice both during winter and summer. In the Arctic, there has been a decline in the sea-ice, primarily during summer when the temperature goes above the freezing point. “This is the South Pole ice, 90% of Earth’s ice, and it’s getting thicker.” Rasmus Benestad Senior scientist, The Norwegian Meteorological institute: The Antarctic ice sheet is losing mass*. Shepherd et al (2018) Mass balance of the Antarctic Ice Sheet from 1992 to 2017, Nature “Greenland is melting a little bit at the edges and getting thicker in the center, but overall the ice is perfectly rock solid, very little change.”Mark Richardson Research Associate, Colorado State University/NASA JPL: This is false. Greenland lost 2+ trillion tonnes of ice since 2002. (For example, see here, here, and here.) Twila Moon Research Scientist, University of Colorado, Boulder: Greenland is losing ice at the edges—both through direct melt and by calving off icebergs—and it is getting thicker in the middle. However, the amount of thickening in the middle is a fraction of the loss at the edges. Instead, the loss at the edges is vastly outpacing new snow accumulation. Ice loss from Greenland has accelerated over the last 3 decades and in the recent decade Greenland has lost about 300 gigatons of ice per year (almost 1 mm of sea level rise per year). This paper[1] provides a good overview. Also, Greenland glacier ice is not ‘rock solid’. Glacier ice flows (think of it as very slow moving rivers), and ice is constantly moving from the center of the ice sheet to the edge. Change has been rapid and large. [1] Bamber et al (2018) The land ice contribution to sea level during the satellite era, Environmental Research Letters “Ocean levels have been rising for the last 20,000 years[…] No climate scientist can tell you when natural sea level rise stopped and man-made sea level rise began.” Stefan Rahmstorf Professor, Potsdam University: False. We have good reconstructions of sea-level changes over the past millennia from sediment cores and other data sources along the world’s coastlines. At least in the past 28 centuries, global sea-level never even remotely rose as much as it did in the 20th Century. And that of course is physically exactly what is expected, given the 20th Century experienced a global warming unprecedented in previous millennia. Figure – The last 2500 years of sea level together with the projections of Kopp et al. for the 21st century. Future rise will dwarf natural sea-level variations of previous millennia."
https://science.feedback.org/review/popular-story-fox2news-accurately-describes-2017-global-temperature-sea-ice-extent-cnn/,1.3,"CNN, Fox News, by Brandon Miller, on 2018-02-26.",,"""NASA releases time-lapse of the disappearing Arctic polar ice cap""",,,,,"This February 2018 article on the website of Fox 2 St. Louis—based on an article syndicated from CNN—reported on 2017 climate data released by NOAA and NASA. It notes that 2017 ranked as the second/third (depending on dataset) warmest year on record, and annually averaged sea ice extent in the Arctic was at its second lowest extent. Scientists who reviewed the article found that it accurately conveyed this information. However, a couple statements lack clarifying details. It is not explained that the sea ice extent numbers given relate to annual mean extent rather than summer minimum extent, for example, or that temperature was given relative to the 1951-1980 average. This is part of a series of reviews of 2018’s most popular climate stories on social media. This article has been shared more than 1.1 million times on social media as of writing, making it the most popular story of 2018 so far.See all the scientists’ annotations in context. You can also install the Hypothesis browser extension to read the scientists’ annotations in context.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Christopher Merchant Professor, University of Reading and UK National Centre for Earth Observation: The NASA movie [below] shows the power of being able to visualise what has been happening to the environment over many years, in this case for Arctic sea ice. The evidence of change is plain to see. The facts-driven description in the article that accompanies the movie addresses developments in other parts of Earth’s climate system straightforwardly and informatively. François Massonnet Postdoctoral Research Fellow, Université catholique de Louvain: The article is factually correct. The reality that Arctic sea ice is getting younger [rather than surviving for several years and growing thicker] is not so well known from the public, so such an article is welcome. The article’s title and the front video are about sea ice, but most of the rest of the text is about global temperatures. There has been clear evidence that the two (rising temperatures and declining sea ice) are linked on long time scales (say, >15 yr), but interannual fluctuations of the latter are more difficult to formally relate to the former. Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: Overall, I thought the article provided a good summary of the major climate features of 2017. The article mentioned a number of geophysical metrics, including sea ice, temperature, extreme events, and snow cover. The article had a good discussion of the impact of natural El Niño/La Niña variability (despite a slightly inaccurate description of El Niño/La Niña), noting that 2017 was the hottest year on record if El Niño/La Niña events are statistically removed. The article also included a brief, but warranted discussion of the Paris Climate Agreement. Caroline Holmes Polar Climate Scientist, British Antarctic Survey: The article is credible and the overall message/insight conveyed to the reader is accurate. However, the reader could be easily misled on some details because some of the values quoted are given with insufficient information and without traceable sources. (The 2017 temperature anomaly quoted is relative to 1951-1980. The Arctic sea ice ‘second lowest’ refers to the annual mean.) Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Annotations: The statements quoted below are from the article; comments are from the reviewers (and are lightly edited for clarity). According to NASA, the globally averaged temperature of the land and ocean was 0.9˚C (1.62˚F) above the 20th century average. This puts us well over halfway to the ambitious target of limiting warming to 1.5˚ C (2.7˚F) set in the 2016 Paris Climate Agreement. Caroline Holmes Polar Climate Scientist, British Antarctic Survey: The source for this information is here. 2017 was 0.9°C warmer than 1951-1980. The Paris agreement target was “[to keep] the global temperature rise this century well below 2 degrees Celsius above pre-industrial levels and to pursue efforts to limit the temperature increase even further to 1.5 degrees Celsius. Pre-industrial is an earlier period than 1950-1981, so “well over halfway… to 1.5°C” is therefore still true. Therefore the spirit of the statement in these sentences is true although the details are slightly inaccurate. Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: I think 2017 was compared to the 1951-1980 average. Note that the Paris target is “to limit the temperature increase to 1.5°C above pre-industrial levels” and the 0.9°C value is relative to 1951 – 1980. El Niño is characterized by a warming of the surface waters in the tropical Pacific Ocean Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: This should be “in the central and eastern-central equatorial Pacific”. La Niñas, on the other hand, feature cooler than average waters in the Pacific Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: This should be “in the eastern equatorial Pacific”. Sea ice continued its declining trend, both in the Arctic and Antarctic.Caroline Holmes Polar Climate Scientist, British Antarctic Survey: It is misleading to already call the recent turn in Antarctic sea ice a declining trend. “Trend” suggests something happening long-term; as stated in the next sentence, the Antarctic downturn is recent. The Antarctic, which was trending at record high levels just a few years ago, reached a record low during 2017 Caroline Holmes Polar Climate Scientist, British Antarctic Survey: Both in the annual-mean and for the minimum extent and other summer months. (See NOAA’s summary.) In the Arctic, sea ice extent was the second-lowest since records began in 1979, behind only 2016, Caroline Holmes Polar Climate Scientist, British Antarctic Survey: This is true for the annual average; for the September minimum extent, which is often discussed, the minimum was 2012."
https://science.feedback.org/review/metros-claims-of-coming-mini-ice-age-have-no-basis-in-reality/,Incorrect,"Metro, Jasper Hamill, 2018-11-16",[S]unspot activity on the surface of our star has dropped to a new low. It’s feared this could herald the arrival of a uniquely grim ‘mini Ice Age’.,,"Misleading: The temperature effect of this low solar activity is primarily felt in the far upper reaches of the outer atmosphere, and is not expected to have any effect on the surface temperatures we experience. Fails to grasp significance of observation: A low point (""minimum"") in the normal 11-year solar activity cycle is not equivalent to a prolonged ""grand minimum"" like the Maunder Minimum that lasted from the mid 1600s to the early 1700s.",Observations have shown that solar flare activity on the surface of the Sun is in the quiet phase of its continuing 11-year cycle. This causes cooling of the thermosphere—a layer of the atmosphere that starts 65 miles above the surface—and will not cause noticeable cooling at the surface.,"Humanity could soon face a long, cold winter which could see temperatures across the planet plunge to depressing lows. <br />A Nasa scientist who [<em>sic</em>] fears sunspot activity on the surface of our star has dropped to a new low. <br />It’s feared this could herald the arrival of a uniquely grim ‘mini Ice Age’.  <br />‘We see a cooling trend,’ Martin Mlynczak of Nasa’s Langley Research Center told Space Weather.",,"UPDATE (22 Nov. 2018): This article was updated after this review was published. The author completely changed the title and the main claim of the article, making it clear that no mini ice age would be imminent,and appended an update statement. See details below. Martin Mlynczak, Senior Research Scientist, NASA Langley Research Center: The claims such as those in the Metro article are false. If you check the original story at Space Weather [the source of the quotes], there is no mention of a mini ice age, nor is there any mention of consequences for weather and climate at Earth’s surface. To emphasize, the cooling effects we are seeing in Earth’s thermosphere are a result of the current solar minimum conditions. The thermosphere is the layer of Earth’s atmosphere beginning 65 miles above Earth’s surface and is highly sensitive to solar activity. There is no relationship between the natural cycle of cooling and warming in the thermosphere and the weather/climate at Earth’s surface. NASA and other climate researchers continue to see a warming trend in the troposphere, the layer of atmosphere closest to Earth’s surface. There is no inconsistency between the science findings of a warming troposphere [where we live] and the Thermosphere Climate Index described above in the Space Weather article. Thermosphere Climate Index through March 2015. Source Satellite-measured troposphere temperatures through October 2018.Source Georg Feulner Senior Scientist, Potsdam Institute for Climate Impact Research (PIK): [This comment taken from an evaluation of a similar statement.] While regional and seasonal effects might be larger, the expected global temperature response to a future grand solar minimum similar to the Maunder Minimum is a cooling of about 0.1°C. It should be pointed out that this cooling would occur on the background of current anthropogenic warming which is about a factor of 10 larger. To claim that “temperatures will fall dramatically” is thus not really justified. It is also clear from these numbers that a future grand solar minimum (which would last only for a few decades anyway) would not save us from global warming, as we have shown in a scientific paper and explained here. The marginal temperature differences between warming scenarios with and without a future Maunder Minimum is illustrated here: Figure – Rise of global temperature for two different emission scenarios (A1B, red, and A2, magenta). The dashed lines show the slightly reduced warming in case a Maunder-like solar minimum should occur during the 21st century. The blue line represents global temperature data. Source: PIK. [Read more about how the claim propagated online: False claims of a coming ice age spread through ecosystem of unreliable news sites, blogs, and social media accounts] UPDATE (22 Nov. 2018): The version of the article liveas of Nov. 22 (the fourth) displays the following update statement: “This article has been amended since initial publication to remove the erroneous suggestion that the possibly record-breaking cooling of the thermosphere, located over 100km above the surface of the Earth, would have the effect on the troposphere of ‘a mini Ice Age’. We are happy to clarify that the record low temperatures reported as part of a natural cycle in solar activity are not inconsistent with current scientific findings of a warming troposphere, and apologise for any contrary impression given.” The original version‘s first paragraphs read: “Humanity is facing a long, cold winter which could see temperatures across the planet plunge to depressing lows. That’s the warning from a Nasa scientist who fears sunspot activity on the surface of our star has dropped so low that it could herald the arrival of a uniquely grim mini Ice Age.” Asecond versionthen read: “Humanity could soon face a long, cold winter which could see temperatures across the planet plunge to depressing lows. A Nasa scientist has revealed that sunspot activity on the surface of our star has dropped to a new low, causing temperatures in the upper layer of our atmosphere to plummet. Other researchers have previously warned that the slowdown in sunspot activity could herald the arrival of a uniquely grim ‘mini Ice Age’.” A third version of the article was then published, which read: “A Nasa scientist has revealed that sunspot activity on the surface of our star has dropped to a new low, causing temperatures in the upper layer of our atmosphere to plummet. Other researchers have previously warned that the slowdown in sunspot activity could herald the arrival of a uniquely grim ‘mini Ice Age’. But the Nasa scientist went on to say that the trend he sees is overall global warming, not cooling, and insisted this ‘solar minimum’ does not mean the world is going to shiver through a depressingly long winter.” The title of the article has also been modified from: “A mini ice age could be on the way and it’s going to get very, very cold” in the second version to “Nasa scientist detects sunspot slowdown – so is a ‘mini Ice Age’ on the way?” in the third version and finally “Nasa scientist says sunspot slowdown will cause temperatures in the upper atmosphere to plunge” in the fourth version."
https://science.feedback.org/review/washington-post-accurately-describes-ocean-warming-study-with-potential-implications-for-future-carbon-budget-chris-mooney-brady-dennis/,1,"The Washington Post, by Brady Dennis, Chris Mooney, on 2018-10-31.",,"""Startling new research finds large buildup of heat in the oceans, suggesting a faster rate of global warming""",,,,,"This article in The Washington Post covers a new study estimating the amount of heat energy that has accumulated in the ocean in recent decades. Such estimates have been limited because the most complete network of ocean temperatures did not exist until the 2000s. The new study uses an indirect method, instead relying on changes in atmospheric gases caused by warmer oceans. This method produces an estimate of ocean warming resulting from human activities that is similar to other estimates, within error bars. Scientists who reviewed the article found that it did a good job of describing the study, while noting that the study’s conclusions (and implications) require additional investigation. In particular, discussion among scientists has focused on clarifying what impact this study’s results have on our understanding of climate sensitivity (how much warming occurs from a given amount of greenhouse gas emissions) and, consequently, how much the world can emit before reaching 2 °C warming. UPDATE (14 Nov 2018): After this evaluation was published, the authors of the study corrected their results to account for mistakes in calculating error bars. While the study previously concluded that ocean warming was greater than earlier estimates showed, those older estimates are now within the expanded error bars of the new work. The summary text above was updated to accurately reflect this relationship. Reviewers’ comments below were based on coverage of the initial version of the study. Read more.See all the scientists’ annotations in context. You can also install the Hypothesis browser extension to read the scientists’ annotations in context.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Mitch Lyle Professor, Sr. Research, Oregon State University: The authors use a novel ocean heat content estimate that depends on gas exchange and atmospheric oxygen content. The conclusion are interesting, that climate sensitivity may be underestimated, but their “thermometer” needs to be confirmed. Pepijn Bakker Assistant professor, Department of Earth Sciences, Vrije Universiteit, Netherlands: The article gives a good and balanced representation of the main new scientific insights. What I find inappropriate about the title is that it suggests that a large buildup of heat in the oceans is a new finding. This has been known for a long time, but what is novel is that this heat buildup now appears much larger than previously assumed. Mark Richardson Research Associate, Colorado State University/NASA JPL: This article covers a study1 that used precise measurements of gases in the air to infer ocean temperature change since 1991. This sounds crazy, but it’s basic physics that warming liquids release dissolved gases. The scientists accounted for other factors, checked against available ocean data and worked out that the oceans have sucked up more heat since 1991 than some other studies reported. The older studies often lacked data from the best instruments in places like the shallow seas around Indonesia so might have missed heat “hiding” in such regions2. The new study led by Dr. Resplandy of Princeton does not have this weakness and so is very credible. The Washington Post article accurately reports the results and links to other topics using reliable sources. Quotations from Pieter Tans and Paul Durack add important caveats showing that this is strong new evidence but not the final say. This caution is vital for readers to interpret the findings. The article then talks about what these results could mean for global warming and related political targets. Most evidence, such as from satellite measurements of how clouds have changed with our warming climate3, suggest that we will see a lot more global warming from our emissions. By contrast, some simple “energy budget” calculations that used ocean heat data suggested less warming, but they relied on lower estimates of heat uptake with non-global measurements. The Post then reports how Resplandy’s new ocean heat findings would affect the “energy budget” results. The numbers they give are based on calculations from the research and are defensible. I take issue with Durack’s quote that this “means the rate of warming and the sensitivity of the Earth’s system to greenhouse gases is at the upper end”. This is vague and probably overconfident: the data fit with a lot of warming in the pipeline, but plugging these numbers into one recent calculation4 could also imply relatively moderate future warming. This is overly harsh criticism for an article that tackles several tricky issues and, in my judgment, provides a well-supported and balanced discussion of a fascinating piece of new science. 1- Resplandy et al (2018)Quantification of ocean heat uptake from changes in atmospheric O2 and CO2 composition, Nature 2- Dieng et al (2015)The Sea Level Budget Since 2003: Inference on the Deep Ocean Heat Content, Surveys in Geophysics 3- Brient and Schneider (2016) Constraints on Climate Sensitivity from Space-Based Measurements of Low-Cloud Reflection, Journal of Climate 4- Lewis and Curry (2018) The Impact of Recent Forcing and Ocean Heat Uptake Data on Estimates of Climate Sensitivity, Journal of Climate Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time."
https://science.feedback.org/review/guardian-story-accurately-describes-study-on-environmental-impacts-of-our-food-system-damian-carrington/,1.5,"The Guardian, by Damian Carrington, on 2018-10-10.",,"""Huge reduction in meat-eating ‘essential’ to avoid climate breakdown""",,,,,"This story in The Guardian covers a newly published study in the journal Nature on the environmental impacts of the food system as global population grows and diets change. The study examines possible changes including reducing the consumption of red meat (which has a large greenhouse gas and water footprint) and reducing the amount of food that spoils before it can be eaten. Different environmental impacts of the food system in 2010, and with projected global changes in 2050. (Source) The study concludes that “no single measure is enough to keep these effects within all planetary boundaries simultaneously, and that a synergistic combination of measures will be needed to sufficiently mitigate the projected increase in environmental pressures.” This is similar to the recently released IPCC report on 1.5 °C warming, which states, “Decreasing food loss and waste and behavioural change around diets could lead to effective mitigation and adaptation options (high confidence) by reducing both emissions and pressure on land, with significant co-benefits for food security, human health and sustainable development, but evidence of successful policies to modify dietary choices remains limited.” The scientists who examined the Guardian article mostly found that it accurately described the study’s conclusions. However, they also found that the headline was sensational and not representative of the study. This post from October 2018 was updated in January 2019 with additional comments as part of a series of reviews of 2018’s most popular climate stories on social media.Read The Guardian article. You can also install the Hypothesis browser extension to read the scientists’ annotations in context.GUEST COMMENTS: Corné van Dooren, Researcher, The Netherlands Nutrition Centre: Although the presented facts are clear, the scientists give a personal interpretation of the priorities and needed policies, which are not covered in the source. The data give added value, but are in line with earlier studies. “Avoid climate breakdown”: Even when meat consumption is reduced, the climate effect will take place. And ‘avoid destroying’ in the subtitle is too strong. The authors state that a combination of measures will be needed to sufficiently mitigate the projected increase in environmental pressures. Arnold Tukker, Professor, Leiden University: If I have any critique is that it is old news. It has been shown zillions of times that reducing meat and dairy reduced climate change problems. Stefan Wirsenius Associate Professor, Chalmers University of Technology: The two main headlines in The Guardian article are not supported by the content in the research paper. First, the statement that “huge reduction in meat-eating is essential to avoid climate breakdown” is not an accurate reflection of the research findings. What the paper does say is that greenhouse gas emissions cannot be mitigated without dietary changes towards more plant-based food. Second, the statement that “huge changes to farming are needed to avoid destroying Earth’s ability to feed its population” is a total misrepresentation of the research. The so-called “huge” changes analyzed in the paper are mainly mainstream technology improvements, such as raised yields, improved fertilizer efficiency, etc. Margaret Gill Professor, University of Aberdeen: The article is accurately based on the scientific publication but also includes comments from two other scientists who were not involved in the research, which strengthens its credibility. The headline just reports one of the findings though, which while accurate also plays to the alarmist rhetoric of newspaper headlines—otherwise I would have given the higher mark. The geographical distinction between UK and global citizens in the graphic is also commendable. Hugo Valin Research Scholar, The International Institute for Applied Systems Analysis: The article provides a rigorous assessment of the overall threats to the climate and the planet, as we are getting towards the challenge of feeding a 10 billion global population. Change in diets will be required due to the high impacts of the livestock sector, but this is not the only lever to use to relieve the level of pressure, and the Nature study also heavily emphasizes the role of technical change, which is less prominent in the Guardian piece. It should also be reminded that most reductions of emissions on non-CO2 emissions from livestock will be needed in developing countries (75% of ruminant emissions, 56% of monogastrics in 2000, see Herrero et al1). Therefore, reducing consumption in rich countries will only have limited impacts if developing countries do not join the efforts. The “flexitarian” diet is also certainly a more promising way forward than a vegan diet, due to nutrition balance considerations, and cultural barriers towards stopping animal based products consumption. The alarming tone could gain to be balanced with the diversity of challenges across different geographies, the role that technology could play to alleviate some adverse impacts, and the fact that climate mitigation in agriculture does not operate in isolation with other sector climate policies, which means the climate mitigation burden could be transferred across sectors and geographies to make the 1.5 or 2 degree C targets bearable for the food and agricultural system without jeopardizing food security2. 1-Herrero et al (2013)Biomass use, production, feed efficiencies, and greenhouse gas emissions from global livestock systems, PNAS 2-Hasegawa et al (2018) Risk of increased food insecurity under stringent global climate change mitigation policy, Nature Climate Change Harry Aiking Associate Professor, Vrije Universiteit Amsterdam: The underlying Nature paper by Springmann et al is clearly a landmark paper. Its contents have been captured in an admirable way by this article in The Guardian. The health issue is underplayed in the latter, however, and does not appear until the very last line. Just eating according to dietary guidelines—thus avoiding obesity and associated diseases—is about as important as adopting a flexitarian diet to both health and sustainability. We urgently need to reduce 1) over-consumption of protein and 2) over-consumption of calories. In addition, 3) reducing food waste, and 4) replacing animal protein with plant protein are also important. For arguments in full, see Aiking and De Boer (2019)*. Aiking and De Boer (2019) The next protein transition, Trends in Food Science & Technology Martin Heller Research Specialist, University of Michigan: The information in the article appears to reflect well the finding of the study covered, and does an excellent job of putting the scientific findings in a “common” context. The findings and their take home message are easily understood. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time."
https://science.feedback.org/review/on-bbc-newsnight-myron-ebell-falsely-claims-climate-models-exaggerate-warming/,Inaccurate,"BBC, Myron Ebell, 2018-10-08",The rate of warming according to the data is much slower than the models used by the IPCC,,Factually Inaccurate: This claim is simply not true—climate models run in the past have accurately predicted the current rate of warming.,"Climate scientists use models to simulate and study different aspects of Earth's climate system, and to project the rate of global warming caused by human activities. These models do, in fact, simulate the rate of global warming well, and models run in the past accurately projected the rate of warming we are currently experiencing.",The rate of warming according to the data is much slower than the models used by the IPCC,,"Reto Knutti Professor, ETH Zürich: [This comment is taken from an evaluation of a similar claim.] The statement that climate models overestimate the warming in response to CO2 is incorrect; it is based on either too short time periods that are dominated by natural variability, by the comparison of models with datasets that do not have global coverage, by comparing to models that were run many years ago with emissions and forcings that differed from what actually happened, by the use of oversimplified energy balance models1, or a combination of it. Recent studies have shown that once the changes in climate feedbacks over time2, datasets with full coverage are considered3 and all forcings are considered, the agreement between predicted and observed warming is excellent, even over the recent hiatus period4. It is remarkable that even projections made decades ago with climate models that were much simpler (and were running on computers that were likely slower than a mobile phone today) were quite accurate5,6,7. 1- Knutti and Rugenstein (2015) Feedbacks, climate sensitivity and the limits of linear models, Philosophical Transactions of the Royal Society A 2- Armour (2017) Energy budget constraints on climate sensitivity in light of inconstant climate feedbacks, Nature Climate Change 3- Richardson et al (2016) Reconciled climate response estimates from climate models and the energy budget of Earth, Nature Climate Change 4- Medhaug et al (2017) Reconciling controversies about the ‘global warming hiatus’, Nature 5- Stouffer and Manabe (2017) Assessing temperature pattern projections made in 1989, Nature Climate Change 6- Fischer and Knutti (2016) Observed heavy precipitation increase confirms theory and early models, Nature Climate Change 7- Allen et al (2013) Test of a decadal climate forecast, Nature Geoscience Patrick Brown Assistant Professor, San Jose State University: [This comment is taken from an evaluation of a similar claim.] This argument reached a peak in popularity around 2012/2013 when the “hiatus” was still ongoing (i.e. when the divergence between observed and modeled global temperature was at its largest). Even then, however, it was shown that you cannot conclude much about sensitivity to CO2 from such short-term fluctuations1. Similarly, Brown et al. (2015)2 showed that decade-long periods without warming are to be expected and that there was/is a 70% chance of seeing at least one 11-year period with no warming between the years of 1993-2050 under a “middle of the road” emissions scenario. Since then, observed warming has surged and, as of 2016, observations are warmer than the average prediction from climate models (see figures below). 1- Marotzke and Forster (2015) Forcing, feedback and internal variability in global temperature trends, Nature 2- Brown et al (2015) Comparing the model-simulated global warming signal to observations using empirical estimates of unforced noise, Scientific Reports Figure – Modeled global surface temperature (RCP 4.5 emissions scenario) compared to observed temperature (NASA GISS). Source Figure – Updated version of IPCC AR5 Figure 11.25a, showing observations and the CMIP5 model projections relative to 1986-2005. The black lines represent observational datasets (HadCRUT4.5, Cowtan & Way, NASA GISTEMP, NOAA GlobalTemp, BEST). Source Markus Donat Research Fellow, University of New South Wales: [This comment is taken from an evaluation of a similar claim.] For example, this study by Rahmstorf and colleagues* shows how projections from past IPCC reports (future projections starting in 1990 and 2000) very well predicted the observed temperature changes since then. Figure – Observed annual global temperature, unadjusted (pink) and adjusted for short-term variations due to solar variability, volcanoes and ENSO (red) compared to the scenarios of the IPCC (blue range and lines from the third assessment, green from the fourth assessment report). Source: Rahmstorf et al (2012) Rahmstorf et al (2012) Comparing climate projections to observations up to 2011, Environmental Research Letters Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: [This comment is taken from an evaluation of a similar claim.] At the surface models predict a rate of warming of 0.2°C per decade since 1970, while NASA observes warming of around 0.18°C during the same period[…] Similarly, the observations from all the different groups that measure global surface temperatures are well within the envelope of model projections: Over a longer timeframe, since we first started observing global temperatures in the late 1800s, models have also matched observations fairly well: Cowtan et al (2015) Robust comparison of climate models with observations using blended land air and ocean sea surface temperatures, Geophysical Research Letters"
https://science.feedback.org/review/guardian-conveys-statement-scientists-stressing-role-of-deforestation-climate-change-oliver-milman/,0.7,"The Guardian, by Oliver Milman, on 2018-10-04.",,"""Scientists say halting deforestation 'just as urgent' as reducing emissions""",,,,,"This story in The Guardian covers a statement released by a group of scientists to highlight several ways in which forests are important to climate change—both because deforestation releases carbon dioxide into the atmosphere and because regrowing and managing forests can help us remove carbon dioxide from the atmosphere. Scientists who reviewed this story found that it accurately reported the statement but note a few places where more clarity could be provided—avoiding the misleading phrase “runaway climate change”, for example. Reviewers also expressed a desire for links to supporting information, most notably the scientists’ statement itself.See all the scientists’ annotations in context. You can also install the Hypothesis browser extension to read the scientists’ annotations in context.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Ben Poulter Research Scientist, NASA: The article correctly links estimates of current carbon dioxide emissions from land use and land cover change with fairly conservative estimates for potential carbon sequestration embedded in “natural climate solutions” as part of the climate mitigation strategy to avoid 1.5°C warming. The article highlights an independent statement (published in advance of the IPCC 1.5 degree report) raising awareness of how Bioenergy with Carbon Capture and Sequestration (BECCS) activities proposed to drawdown atmospheric carbon dioxide pose negative consequences for unmanaged forests by replacing them with oil crops. The potential trade-offs of BECCS on ecosystem services provided by forests, on food security, water resources, and their effectiveness as a climate mitigation strategy are not well understood, but the risks are included in the Summary: for Policymakers (SR15 SPM Final of the IPCC 1.5 degree report) published Oct 8, 2018. Land-use and land-cover change is responsible for roughly 10-15% of total global carbon dioxide emissions. Forest management, reforestation, and afforestation where appropriate, is part of the climate mitigation portfolio assessed by Integrated Assessment Models used in the IPCC process. Trade-offs between the ecosystem services forests provide and BECCS, which requires large land area conversion to oil seed crops are limiting the scope of this strategy, and focusing attention on mitigating carbon dioxide from fossil fuel sources directly. Devaraju Narayanappa Postdoctoral research fellow, Université de Versailles Saint-Quentin (UVSQ-CEA-CNRS): Overall, the article accurately conveys the main message from the world’s leading scientist signatories: “on the importance of protecting forests to avoid dangerous climate change”. Some words are bit subjective (e.g. “to avoid runaway climate change”, “overlooked by the world’s governments”), but generally the article is very well informed with no inaccuracies. Julia Nabel Scientific Programmer, Max Planck Institute for Meteorology: The article mainly summarises a statement of 40 scientists titled “Five Reasons the Earth’s Climate Depends on Forests”. Unfortunately it does not provide the link to the original statement which is quite short and easy to read. Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: This article was a good summary of a statement on the importance of forests in combating climate change (signed by 40 scientists). I thought this article was fine (minus the “runaway climate change” statement). I didn’t think it was substantially more clear than the original statement. Ana Bastos Group Leader, Max Planck Institute for Biogeochemistry: The article largely reflects the statement of the group of scientists—which in itself is accurate and referenced. However, the journalist could have made a bigger effort to direct readers to the appropriate references (a link to the original statement would have already been very helpful). Moreover, the statement reflects a perspective of a group on the relevance of forests in the context of climate change mitigation. Even though I share this perspective, a journalist should have set this statement in the context of other studies / perspectives about mitigation options. Alexis Berg Research Associate, Harvard University: This article does a decent job at reporting on a recent statement by some scientists, based on the latest peer-reviewed science, emphasizing the importance of forest protection and restoration as a tool to combat climate change, as the IPCC is releasing a report regarding the current trajectory of global warming and mitigation strategies. A bit more clarity would have been welcome in the article about some points in the statement, for instance regarding the importance of large-scale “bioenergy with carbon capture and storage” technology that needs to be deployed for low-climate change scenarios and the danger this approach, somewhat paradoxically, poses to the world’s forests. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Annotations: The statements quoted below are from the article; comments are from the reviewers (and are lightly edited for clarity). Scientists say halting deforestation ‘just as urgent’ as reducing emissions The original statement says: halting fossil fuel use, which is different than reducing emissions since e.g. deforestation also leads to emissions. Protecting and restoring forests would reduce 18% of emissions by 2030 The original statement says: could provide 18%[v] of cost-effective mitigation through 2030. help to avoid global temperature rise beyond 1.5°C The original statement sounds much less optimistic, it states: …in order to have a chance of limiting warming to 1.5°C, we cannot emit more than about 750 billion tons … forests store enough carbon to release over 3 trillion tons … if destroyed. And further: Achieving the 1.5°C goal also requires massive forest restoration Razing the world’s forests would release more than 3 trillion tons of carbon dioxide, more than the amount locked in identified global reserves of oil, coal and gas. Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: This was Reason 1 in the original statement. to avoid runaway climate change Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: “Runaway climate change” is too strong here. The original statement says: These “natural climate solutions” could provide 18%[v] of cost-effective mitigation through 2030, which is in reference to avoiding 2°C of climate change. This information relates to reason 2 in the original statement. Alexis Berg Research Associate, Harvard University: I agree, “runaway climate change” is too strong here. It has a precise definition. Warming beyond 2°C, say by 3 or 4°C, is bad, but not the same as “runaway” (which, in my view at least, means that warming would then take a dynamics of its own, stop responding to any emission changes and slip up to several more degrees….). spanning five countries Going quickly through the authors I identified 7 countries: Brasil, US, France, Austria, Italy, Canada, United Kingdom (the list might not be complete). It is expected the report will focus on required changes to the energy system, rather than forests. Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: This appears to be the motivation for the authors’ statement. I don’t know if it is true that the role of forests will be under-appreciated (in the to-be-released IPCC report)—it would have been useful to get more perspective on this—but it is certainly reasonable to highlight the importance of forests. “In responding to the IPCC report, our message as scientists is simple: Alexis Berg Research Associate, Harvard University: This might give the impression that the authors of this statement are separated from the IPCC community. It’s more complicated than that: some of the authors here are also IPCC contributors. They may have felt, however, that not enough emphasis was placed in the latest IPCC discussions and report on the role of forest protection and restoration as a mitigation option to climate change. So it’s more a matter of nuances than opposition. “We almost take forests as a given but we lose forest every year, which means we are diminishing them as a carbon sink. Alexis Berg Research Associate, Harvard University: Deforestation does happen every year, but on the whole, the latest research suggests that we are currently (over the last 30 years) slightly gaining forests globally (+7% compared to early 80’s), as forest gains outside of the Tropics, in particular in the Northern Hemisphere, are a bit greater than tropical deforestation*. We could certainly limit deforestation to gain even more forests, though. In addition, from a carbon perspective and local climate regulation, tropical forests are probably more important than mid-/high-latitude forests. Song et al (2018) Global land change from 1982 to 2016 Nature bioenergy with carbon capture and storage (Beccs), is untested The statement says: untested at large scale. It breaks my heart to think we’d lose half our tropical forests for plantations just to save ourselves Alexis Berg Research Associate, Harvard University: So this seems to suggest that half of tropical forests are supposed to be cleared to make room for large-scale BECCS in scenarios where global warming is limited to 1.5C (or even 2C). This seems like it could have been described more clearly than in passing, in that quote.“It’s horrifying that we’d lose our biodiversity to avert climate change. Losing tropical forests is not somehow cheaper than putting up wind farms in the US or Sahara.” Indeed. But it’s not clear that the report will make (makes) such suggestion. The trade-offs between the different options are mentioned in Chapter 2—but agree that not as highlighted as they probably should. Lawrence said a steep drop in emissions to zero by 2040 would negate the need for “negative emissions” technology that would damage forests’ ability to suck up carbon, maintain local water supplies and weather patterns and provide a home for a riot of birds, mammals, insects and other creatures. It would have been good to add references for this statement. IPCC report warning last week the world is “nowhere near on track” to meet its Paris commitments Alexis Berg Research Associate, Harvard University: Absent further commitments, the Paris pledges are not consistent with a 1.5°C warming target—more like 3°C."
https://science.feedback.org/review/usa-today-op-ed-ignores-evidence-to-claim-climate-change-had-no-role-in-hurricane-florence-roy-spencer/,-1.5,"USA Today, by Roy Spencer, on 2018-09-14.",,"""Hurricane Florence is not climate change or global warming. It's just the weather.""",,,,,"This op-ed in USA Today makes the claim that Hurricane Florence has no appreciable contribution from human-caused climate change. Scientists who reviewed the article found that it ignores the evidence for trends in tropical cyclone behavior, including slower movement speed and more intense rainfall. Additionally, sea level rise raised the storm surge of the landfalling tropical cyclone above the level it would have reached a century ago. The article cherry-picks data in misleading way to claim that recent storms are no different from past tropical cyclones, but does not provide the analysis necessary to support this claim. Published research on the topic does, in fact, show that climate change affects tropical cyclones like Florence. While it is unpublished and preliminary, an early analysis by researchers at Stony Brook University and Lawrence Berkeley National Laboratory suggested human-induced warming could have increased Florence precipitation near its maximum by up to 50%, and more extensive research showed it contributed 15%[1] to 20%[2,3] increased rainfall for Hurricane Harvey. This is due to the fact that warmer air can hold more water vapor[4], which increases hurricanes intensity and rainfall. [1] – van Oldenborgh et al (2017) Attribution of extreme rainfall from Hurricane Harvey, August 2017, Environmental Research Letters. [2] – Wang et al (2018)Quantitative attribution of climate effects on Hurricane Harvey’s extreme rainfall in Texas, Environmental Research Letters. [3] – Risser and Wehner (2017) Attributable Human‐Induced Changes in the Likelihood and Magnitude of the Observed Extreme Precipitation during Hurricane Harvey, Geophysical Research Letters. [4] – Wentz et al (2007) How Much More Rain Will Global Warming Bring?, Science.See all the scientists’ annotations in context. You can also install the Hypothesis browser extension to read the scientists’ annotations in context.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Dan Chavas Assistant Professor, Purdue University: The article’s principal argument is that a climate change effect on the speed of motion of a storm like Florence “is small, probably temporary, and most likely due to natural weather patterns”. But the author provides no evidence for this argument and ignores recent research providing clear evidence that 1) storms are slowing down in observations, and 2) that this is likely to continue in the future under climate change. Beyond this, the author makes various other statements that, whether accurate or inaccurate, are largely irrelevant to the topic of Florence. Andrew Dessler Professor, Texas A&M University: The scientific community has developed analytic tools to determine to what extent a warming climate has affected hurricanes (e.g.*). Dr. Spencer’s position is not backed up by any analysis—rather, it’s the result he wishes were true. I wish we weren’t making hurricanes worse too, but I am convinced by the scientific analyses that we are. Holland and Bruyere (2013)Recent intense hurricane response to global climate change, Climate Dynamics. Walsh et al (2015)Tropical cyclones and climate change, WIREs Climate Change. James Elsner Professor, Florida State University: There are strong theoretical reasons to expect stronger hurricanes under global warming*. These reasons are ignored by the author. Kang and Elsner (2015)Climate Mechanism for Stronger Typhoons in a Warmer World, Journal of Climate. Knutson et al (2010) Tropical cyclones and climate change, Nature Geoscience. Sobel et al (2016) Human influence on tropical cyclone intensity, Science. Kerry Emanuel Professor of Atmospheric Science, MIT: The article trots out the time-worn non sequitur that since climate has changed in the past we need not worry about it changing in the future. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Annotations: The statements quoted below are from the article; comments are from the reviewers (and are lightly edited for clarity). The theory is that tropical cyclones have slowed down in their speed by about 10 percent over the past 70 years due to a retreat of the jet stream farther north, depriving storms of steering currents and making them stall and keep raining in one location. Kerry Emanuel Professor of Atmospheric Science, MIT: This is not based on theory but on solid observational data* that show that tropical cyclone translation speeds have been decreasing. Kossin (2018) A global slowdown of tropical-cyclone translation speed, Nature But like most claims regarding global warming, the real effect is small, probably temporary, and most likely due to natural weather patterns Kerry Emanuel Professor of Atmospheric Science, MIT: Three independent peer-reviewed studies* of Hurricane Harvey concluded that the probability of hurricane rains of that magnitude in Houston have already increased by factors of 2-3 since the middle of the 20th century. These are not small changes. Emanuel (2017) Assessing the present and future probability of Hurricane Harvey’s rainfall, PNAS van Oldenborgh et al (2017) Attribution of extreme rainfall from Hurricane Harvey, August 2017, Environmental Research Letters Risser and Wehner (2017) Attributable Human‐Induced Changes in the Likelihood and Magnitude of the Observed Extreme Precipitation during Hurricane Harvey, Geophysical Research Letters Coastal lake sediments along the Gulf of Mexico shoreline from 1,000 to 2,000 years ago suggest more frequent and intense hurricanes than occur today. Kerry Emanuel Professor of Atmospheric Science, MIT: It is true that coastal lake sediments indicate more risk in certain places than can be assessed with the very short and poor historical records. The authors of at least one of these studies attributed this not to climate change but to the problems of assessing current risk using only the historical record. Liu and Fearn (2000)Reconstruction of Prehistoric Landfall Frequencies of Catastrophic Hurricanes in Northwestern Florida from Lake Sediment Records, Quaternary Research The Massachusetts Bay Colony in 1635 experienced a Category 3 or 4 storm, with up to a 20-foot storm surge. While such a storm does not happen in New England anymore, it happened again there in 1675, with elderly eyewitnesses comparing it to the 1635 storm. Kerry Emanuel Professor of Atmospheric Science, MIT: This is highly misleading and inaccurate. Most evidence points to three major events of comparable magnitude in New England, in 1635, 1815, and 1938. Major New England hurricanes are far too rare to pick out any climate signal. But this does not mean that the underlying probabilities are not changing. The flooding caused by Hurricane Sandy would likely not have occurred without the increase in sea level that has demonstrably taken place since the city’s early history. Nine years into that 11-year hurricane drought, a NASA scientist computed it as a 1-in-177-year event. Kerry Emanuel Professor of Atmospheric Science, MIT: The paper the author quotes concluded that “A hurricane climate shift protecting the U.S. during active years, even while ravaging nearby Caribbean nations, would require creativity to formulate. We conclude instead that the admittedly unusual 9 year U.S. Cat3+ landfall drought is a matter of luck.” Hall and Hereid (2015) The frequency and duration of U.S. hurricane droughts, Geophysical Research Letters. Well, aren’t we being told these storms are getting stronger on average? The answer is no. The 30 most costly hurricanes in U.S. history (according to federal data from January) show no increase in intensity over time. Kerry Emanuel Professor of Atmospheric Science, MIT: U.S. landfalling hurricanes constitute only about 4% of all tropical cyclones, and landfall occupies only a small percentage of their lifetimes. Examination of global data does suggest some increase in tropical cyclone intensity*, along the lines of predictions made 30 years ago. Elsner et al (2008) The increasing intensity of the strongest tropical cyclones. Nature Webster et al (2005) Changes in Tropical Cyclone Number, Duration, and Intensity in a Warming Environment, Science. The monetary cost of damages has increased dramatically in recent decades, but that is due to increasing population, wealth and the amount of vulnerable infrastructure. It’s not due to stronger storms. Kerry Emanuel Professor of Atmospheric Science, MIT: The main problem in the U.S. and many other places is unwise policy that encourages coastal development. Lawmakers have tried to change such policies only to get strong push-back from coastal property owners, whom the rest of us are forced to subsidize. While I agree with the author that this is the most important problem, it is being compounded by climate change, including sea-level rise. If humans have any influence on hurricanes at all, it probably won’t be evident for many decades to come Kerry Emanuel Professor of Atmospheric Science, MIT: In many metrics, it is already evident (e.g. for rain*). Waiting for the signal to emerge unambiguously before acting would be foolish, particularly when, by then, it would be too late. No battlefield general would ever take such a position. Damage and loss of life from weather hazards is done mainly by events rare enough that human society has not adapted to them. The incidence of such rare events is affected disproportionately by climate change, even while changes in such rare events are, by definition, hard to detect in historical data. Mitigating risk means acting on the best available evidence, and the best scientific evidence available suggest that hurricane risks will increase quite substantially as the climate warms. Emanuel (2017) Assessing the present and future probability of Hurricane Harvey’s rainfall, Proceedings of the National Academy of Sciences. van Oldenborgh et al (2017) Attribution of extreme rainfall from Hurricane Harvey, August 2017, Environmental Research Letters."
https://science.feedback.org/review/guardian-story-accurately-covers-sea-ice-event-but-makes-unsupported-connection-weather-patterns-gulf-stream-jonathan-watts/,1.3,"The Guardian, by Jonathan Watts, on 2018-08-21.",,"""Arctic’s strongest sea ice breaks up for first time on record""",,,,,"This article in The Guardian describes unusual Arctic sea ice conditions north of Greenland, where an area normally covered by old and thick ice expected to be the last to melt due to global warming has broken up this year. Scientist who reviewed the article found that this event was accurately discussed, but the end of the article makes questionable connections between Arctic conditions and heatwaves and fires in Europe and Siberia, as well as the Gulf Stream circulation of the Atlantic Ocean. While the relationship between Arctic sea ice conditions and midlatitude weather patterns like heatwaves is a topic of current research that is still unclear. Atlantic Ocean circulation, however, is not believed to be connected to lingering weather systems, as the article states.See all the scientists’ annotations in context. You can also install the Hypothesis browser extension to read the scientists’ annotations in context.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Robert Graham Postdoc, Norwegian Polar Institute: The article is clear and accurate. The authors have consulted several experts in the field to develop this story. They provide a scientifically sound overview of the current sea ice state north of Greenland, its historical context, and what has caused this anomaly. The reason for not providing a +2 rating relates to the second last paragraph, and statements regarding the Gulf Stream: “This includes the Gulf Stream, which is at its weakest level in 1,600 years due to melting Greenland ice and ocean warming. With lower circulation of water and air, weather systems tend to linger longer.” It is fair to say the Gulf Stream is weakening/at its weakest in 1600 years1. However, there is no clear link between changes in the Gulf Stream and Polar Vortex or the current Arctic sea ice state. No reference is provided in the article to support such a link. A weaker polar vortex (circulation of air) has been linked to slower moving weather systems2. However, the link between a reduced strength of the Gulf Stream (circulation of water) and slower moving weather systems is not clear. No reference is provided. Finally, the expression “dormant hot front” is unfamiliar/unclear in the final paragraph. I think it would be better to say slower moving weather systems. 1-Thornalley et al (2018)Anomalously weak Labrador Sea convection and Atlantic overturning during the past 150 years, Nature 2-Kretschmer et al (2017)More-Persistent Weak Stratospheric Polar Vortex States Linked to Cold Extremes, Bulletin of the American Meteorological Society Michel Tsamados Lecturer (Assistant Professor), University College London: Clear article highlighting a rare regional event symptomatic of thinner more mobile sea ice. It would have been nice to give some general background on how rare this event really is. Keld Qvistgaard cites earlier evidence of such event but we are not told how frequent these have been while others (i.e., Gavin Schmidt from NASA) have likened this event to the type of condition present in this region in the early Holocene (6,000 to 8,500 years ago). Angelika Renner Researcher, Institute of Marine Research, Tromsø, Norway: The article accurately describes the observed sea ice breakup north of Greenland, with decent background information both on the “normal” state of the sea ice in this region and on what has happened now. While the general concerns by scientists regarding this opening are conveyed in a decent way, the last paragraphs of the article linking this sea ice anomaly to a weakening Gulf Stream and forest fires in Scandinavia are not well supported. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Annotations: The statements quoted below are from the article; comments are from the reviewers (and are lightly edited for clarity). “The sea off the north coast of Greenland is normally so frozen that it was referred to, until recently, as ‘the last ice area’ because it was assumed that this would be the final northern holdout against the melting effects of a hotter planet. But abnormal temperature spikes in February and earlier this month have left it vulnerable to winds, which have pushed the ice further away from the coast than at any time since satellite records began in the 1970s.” Julienne Stroeve Senior Research Scientist, University College London: I find this story to be a bit off. For one, we had open water develop here during February. It was likely unprecedented then, though I haven’t been able to verify this yet as I don’t have high resolution data far back in time. I do have plans to investigate this more. Anyway, since open water developed in February, this implies new ice formation, which would have been substantially thinner than the ice that had been there. Thus, having the opening happen again this summer is tied to the February event, so it is somewhat expected that it would happen again in summer. Temperatures have not been all that warm this summer in the Arctic, but if the winds are right you can push this thinner ice away from the shore. Jennifer Francis Senior Scientist, Woods Hole Research Center: This statement is consistent with our many lines of evidence that sea ice has been steadily thinning. The thickest ice types have become increasingly rare. Thinner ice is more easily pushed around by the winds, so it is no surprise that the right wind patterns could move it farther offshore. “During the sunless winter, a heatwave raised concerns that the polar vortex may be eroding. This includes the Gulf Stream, which is at its weakest level in 1,600 years due to melting Greenland ice and ocean warming. With lower circulation of water and air, weather systems tend to linger longer.” Julienne Stroeve Senior Research Scientist, University College London: Certainly breakdown of the polar vortex allows for cold air to spill out of the Arctic (which is part of why the UK was so cold last winter). Several studies are strongly suggesting that the loss of winter ice in the Barents Sea is the driver for a weaker polar vortex, though this remains debated in the science community. Jennifer Francis Senior Scientist, Woods Hole Research Center: This statement seems to mix up some hypothesized connections among observed changes. The polar vortex did experience a disruption this past winter and likely contributed to heat waves near the North Pole, but the connection to the Gulf Stream is unclear. Increased melting of the undersides of Greenland’s outflow glaciers is fueled by warmer oceans, but there is no evidence suggesting that additional melt is causing weather systems to linger longer. Enhanced Arctic warming is believed to be causing more persistent weather patterns under certain conditions, however."
https://science.feedback.org/review/ian-plimer-wrongly-claims-that-carbon-dioxide-emissions-do-not-cause-climate-change/,Incorrect,"The Australian, Ian Plimer, 2018-08-07",there is no relationship between temperature and carbon dioxide emissions by ­humans[...] carbon dioxide has had a minuscule effect on global climate,,"Misleading: Water vapor accounts for a significant portion of the total greenhouse effect, but the water cycle means that temperature controls the amount of water vapor in the atmosphere. Water vapor emissions do not cause climate change; CO2 emissions do. Inaccurate: There is, in fact, a clear relationship between temperature and human-caused emissions of CO2 and other greenhouse gases.","While CO2 constitutes a small percentage of the gases in the atmosphere, it is a critically important ""knob"" controlling Earth's climate. When the concentration of CO2 increases, more outgoing heat energy is absorbed, raising surface temperatures.","Even in our own lifetimes, there is no relationship between temperature and carbon dioxide emissions by ­humans, yet there is a very close relationship between solar activity and temperature.  <br />Since the beginning of time, water vapour has been the main greenhouse gas and carbon dioxide has had a minuscule effect on global climate.<br /> Carbon dioxide is a trace gas in the atmosphere. We are expected to believe that emission of traces of a trace gas into the atmosphere is a major planetary driving force.",,"Mark Richardson Research Associate, Colorado State University/NASA JPL: It’s expected that cumulative human emissions and temperature will correlate1. They do. Since 1970 the correlation is extremely strong: almost 90% of all temperature change correlates with human emissions. About 0.2% correlates with solar activity, and even that is nonsense because temperatures went up while we measured the Sun getting cooler. This [claim] is also nonsense because carbon dioxide heating has been directly measured. Satellite data was reported in 20012. And surface data in 2015. The extra heating we’ve caused through carbon dioxide3is enough to charge more than 700,000 DeLorean’s flux capacitors every second. Or blowing up about 10 Trinity test nukes every second. 1-Zickfeld et al (2016) On the proportionality between global temperature change and cumulative CO2 emissions during periods of net negative CO2 emissions, Environmental Research Letters 2-Harries et al (2001) Increases in greenhouse forcing inferred from the outgoing longwave radiation spectra of the Earth in 1970 and 1997, Nature 3-Feldman et al (2015) Observational determination of surface radiative forcing by CO2 from 2000 to 2010, Nature Katrin Meissner Professor, University of New South Wales: It is true that water vapour is a main greenhouse gas, but the amount of water vapour is also tightly related to temperatures (and should therefore be seen as an enhancing feedback, not a driver). That is, higher CO2 will increase temperatures, which will increase water vapour, which will increase temperatures… To write that “carbon dioxide has had a minuscule effect on global climate” is of course utter nonsense—see other comments. Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: This is a non-sequitur: “CO2 can’t have a large impact on climate because water vapour is Earth’s primary greenhouse gas”. The reality, of course, is that the amount of water vapour in the atmosphere is relatively stable and bound by atmospheric temperature. CO2, on the other hand, can be easily added to the atmosphere in large amounts, altering the Earth’s energy balance and climate in the process. Victor Venema Scientist, University of Bonn, Germany: Naturally also small concentration can matter. Many substances are, for example, poisonous at much smaller concentrations. What matters is the amount of CO2. That there are also inert molecules in the atmosphere does not change the radiative influence of CO2. It is pretty amazing that Plimer states in this same article that “Over the past 30 years, planet Earth has greened due to a slight increase in atmospheric carbon dioxide.” Suddenly it is no problem that CO2 is a trace gas."
https://science.feedback.org/review/ian-plimers-op-ed-incorrectly-claims-human-caused-emissions-are-short-lived/,Misleading,"The Australian, Ian Plimer, 2018-08-07","The ­atmospheric residency time of carbon dioxide is five years and it is quickly sequestered into plants, marine life, oceans and sediments.",,Misleading: The residence time of a molecule of CO2 is not the same as the length of time that human-caused emissions keep the amount in the atmosphere elevated.,"Carbon dioxide flows through the atmosphere, ocean, land ecosystems, and rock of the Earth. Human emissions have pushed these flows out of balance, causing CO2 to accumulate in the atmosphere, strengthening the greenhouse effect for hundreds to thousands of years.","The ­atmospheric residency time of carbon dioxide is five years and it is quickly sequestered into plants, marine life, oceans and sediments.",,"Peter Landschützer Group Leader, Max Planck Institute for Meteorology: This statement of the “short residence time” has been misused in the past. This statement ignores the fact that there is a dynamic exchange between the atmosphere and the ocean. See e.g. Figure 6-01 in the IPCC 2013 report(copied below)—while the ocean indeed takes up about 80 billion metric tonnes of Carbon per year from the atmosphere, it also releases about 78 billion metric tonnes of Carbon per year back, hence CO2 molecules are not immediately sequestered as suggested by the author, but are subject to a dynamical exchange leaving the annual net sequestration to be on the order of 2billion metric tonnes of Carbon per year, or only roughly 20-25 % of the annual human-caused CO2 emissions. This number is supported by models and measurements of the partial pressure of carbon dioxide in the ocean. Figure– Simplified schematic of the global carbon cycle. Source Katrin Meissner Professor, University of New South Wales: There are many papers that looked at the time it would take for natural negative feedbacks to remove the excess carbon from the atmosphere. It would take millennia*. Eby et al (2008)Lifetime of Anthropogenic Climate Change: Millennial Time Scales of Potential CO2 and Surface Temperature Perturbations, Journal of Climate"
https://science.feedback.org/review/op-ed-in-the-australian-gets-nearly-every-fact-wrong-ian-plimer/,-2,"The Australian, by Ian Plimer, on 2018-08-07.",,"""Repeat after me: carbon dioxide is good for us""",,,,,"This op-ed published by The Australian, written by Ian Plimer, makes a large number of claims that run counter to science and observations or are the expression of fallacious reasoning. The title of the op-ed—”Repeat after me: carbon dioxide is good for us”—reflects how it rejects evidence of harmful consequences of human-caused climate change and only cherry-picks a few possible benefits. Scientists who reviewed the story found that it distorted or ignored published research on many topics. Plimer also does not support his extraordinary claims with evidence or research.See all the scientists’ annotations in context. You can also install the Hypothesis browser extension to read the scientists’ annotations in context. REVIEWERS’ OVERALL FEEDBACK: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Richard Betts Professor, Met Office Hadley Centre & University of Exeter: This deeply ill-informed article repeats several of well-worn but deeply misleading and mistaken assertions, which have been shown to be wrong many times. Katrin Meissner Professor, University of New South Wales: This article is an impressive collation of the well known, scientifically wrong, and overused denier arguments. It is ideologically motivated and, frankly, utter nonsense. Martin Singh Postdoctoral Research fellow, Harvard University: This article is appalling in its misrepresentation of climate science. A large majority of the statements made about the science of climate change are misleading or flat out wrong. Human emissions have increased the carbon dioxide concentration on Earth by over 40%, but Plimer’s article gives the impression that the human contribution is negligible. There are mountains of evidence that carbon dioxide has played a major role in influencing Earth’s climate now and in the distant past, but Plimer rejects this with no justification. Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: This article is an amalgamation of logical fallacies, misleading talking points, and downright factually incorrect statements regarding the physics of the climate system. Every talking point in this article has been debunked many times over and it is astonishing that this was published. Peter Landschützer Group Leader, Max Planck Institute for Meteorology: The article contains several inaccuracies and false statements. Furthermore, flawed reasoning is used, such as the “short atmospheric residence time” argument. Twila Moon Research Scientist, University of Colorado, Boulder: The article includes many outright lies as well as unrelated points made to feel as though they are connected to climate. I am actually surprised that any news outlet would publish an opinion piece with so many falsehoods, easily debunked by even cursory reference to decades of published work from scientists and scientific organizations around the globe. An appalling piece of rhetoric. Mark Richardson Research Associate, Colorado State University/NASA JPL: This article claims things that aren’t true. For example, 1980s papers calculate the importance of clouds, climate models projected many changes we’ve now seen and almost all of the increase in atmospheric carbon dioxide is due to human emissions. Temperatures correlate strongly with cumulative human emissions and since 1980 the correlation with solar activity is almost zero. There are false statements about all these and more. A 1990s judgment applies to this article: “everyone in this room is now dumber for having listened to it”. (This rating is a personal opinion and does not reflect the views of any of my employers or affiliations.) Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Annotations: The statements quoted below are from the article; comments are from the reviewers (and are lightly edited for clarity). by Ian Plimer Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: Ian Plimer is not a climate scientist (he is a geologist by training) and has a long and well established history with the mining and fossil fuel industry. This should have been clearly disclosed at the end of the article due to the obvious conflict of interest. More than 100 climate models over the past 30 years did not predict what actually happened because it was assumed carbon dioxide had the pivotal role in driving climate change and that the effects of clouds, back-radiation and the sun were trivial. Mark Richardson Research Associate, Colorado State University/NASA JPL: Climate model projections from decades ago accurately predicted: (1) global warming would happen, (2) it would happen faster at high latitudes, (3) the Hadley Cell circulation would expand poleward, (4) the stratosphere would cool, (5) Arctic sea ice would retreat, (6) convective cloud tops in the tropics would get higher. These changes have all now been measured. For example, a 1988 study1 discussed rising convective cloud tops. And a 2016 study2 showed it was measured with satellites. 1-Wetherald and Manabe (1988) Cloud Feedback Processes in a General Circulation Model, Journal of the Atmospheric Sciences 2-Norris et al (2016) Evidence for climate change in the satellite cloud record, Nature Peter Neff Assistant Research Professor, University of Minnesota: Rather than take Plimer’s word for this, a quick google of climate model predictions (and some evaluation of the quality of sources) will lead you to actual comparison of early climate model projections versus observations. Plimer’s statement is simply not true, climate model projections have been surprisingly accurate despite the simplicity of early computer models. As for the relative contribution of various factors to this warming, carbon dioxide and other greenhouse gases are indeed much more important than other factors like clouds and the sun. See excellent visuals of this here. it was assumed carbon dioxide had the pivotal role in driving climate change and that the effects of clouds, back-radiation and the sun were trivial. Mark Richardson Research Associate, Colorado State University/NASA JPL: It was not assumed carbon dioxide had a pivotal role, this is calculated using equations based on physics. The effect of clouds… was not assumed, but is a result of equations you get from physics.Here is a 1989 study* that talks about how important clouds are. “Back radiation” is included in all climate models and comes from carbon dioxide, among other gases.The Sun’s activity is included in climate models, although it has been generally cooling if anything over the last 40+ years. Cess et al (1989) Interpretation of Cloud-Climate Feedback as Produced by 14 Atmospheric General Circulation Models, Science Climate projections also assume that planet Earth is not dynamic Mark Richardson Research Associate, Colorado State University/NASA JPL: This is nonsense. The models assume that physics works and just implement equations in a way that computers can munch through them. This makes them imperfect, but this statement shows complete cluelessness about models or physics. Climate projections also assume […] that a temporary terrestrial vertebrate on an evolving planet can change major planetary and extraterrestrial systems. Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: This is the “argument from incredulity” logical fallacy. Ian Plimer is so bemused by the physics of climate change science, he refuses to accept its conclusions. Unless the past is understood, climate projections can be only highly speculative. Katrin Meissner Professor, University of New South Wales: The past is quite well understood. Ice cores record the tight correlation between CO2 and temperatures over the past 800,000 years. And climates that experienced CO2 concentrations comparable to today’s for thousand of years were very warm, much warmer than today, because the climate system had time to adapt to these high greenhouse concentrations*. Fischer et al (2018) Palaeoclimate constraints on the impact of 2 °C anthropogenic warming and beyond, Nature Geoscience Peter Neff Assistant Research Professor, University of Minnesota: It is lucky then that we have so many paleoclimate archives that do place our current climate changes in context with the past! Let’s take a look at what the Antarctic ice core record tells us. From this archive we can directly measure CO2 concentrations and use water stable-isotopes as a proxy for temperature. Australian Antarctic scientist Tas van Ommen shows that CO2 and temperature are clearly linked over the past 800,000 years (see figure below). If you prefer NASA as your arbiter of evidence/fact, go for their presentation of ice core data. https://science.feedback.org/wp-content/uploads/2018/08/ice-core-CO2-temperature.mp4 there is no relationship between temperature and carbon dioxide emissions by ­humans Richard Betts Professor, Met Office Hadley Centre & University of Exeter: Actually there is a relationship if you look on the appropriate timescales. Mark Richardson Research Associate, Colorado State University/NASA JPL: It’s expected that cumulative human emissions and temperature will correlate*. They do. Since 1970 the correlation is extremely strong: almost 90% of all temperature change correlates with human emissions. About 0.2% correlates with solar activity, and even that is nonsense because temperatures went up while we measured the Sun getting cooler. Zickfeld et al (2016) On the proportionality between global temperature change and cumulative CO2 emissions during periods of net negative CO2 emissions, Environmental Research Letters water vapour has been the main greenhouse gas and carbon dioxide has had a minuscule effect on global climate Katrin Meissner Professor, University of New South Wales: It is true that water vapour is a main greenhouse gas, but the amount of water vapour is also tightly related to temperatures (and should therefore be seen as an enhancing feedback, not a driver). That is, higher CO2 will increase temperatures, which will increase water vapour, which will increase temperatures… To write that “carbon dioxide has had a minuscule effect on global climate” is of course utter nonsense—see other comments. Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: This is a non-sequitur: “CO2 can’t have a large impact on climate because water vapour is Earth’s primary greenhouse gas”. The reality, of course, is that the amount of water vapour in the atmosphere is relatively stable and bound by atmospheric temperature. CO2, on the other hand, can be easily added to the atmosphere in large amounts, altering the Earth’s energy balance and climate in the process. Carbon dioxide is a trace gas in the atmosphere. Victor Venema Scientist, University of Bonn, Germany: This is the first officially true sentence due to its brevity. The rest of the paragraph shows it is intended to suggest something that is wrong. Mark Richardson Research Associate, Colorado State University/NASA JPL: This paragraph is also nonsense because carbon dioxide heating has been directly measured. Satellite data was reported in 20011. And surface data in 2015. The extra heating we’ve caused through carbon dioxide2 is enough to charge more than 700,000 DeLorean’s flux capacitors every second. Or blowing up about 10 Trinity test nukes every second. 1-Harries et al (2001) Increases in greenhouse forcing inferred from the outgoing longwave radiation spectra of the Earth in 1970 and 1997, Nature 2-Feldman et al (2015) Observational determination of surface radiative forcing by CO2 from 2000 to 2010, Nature We are expected to believe that emission of traces of a trace gas into the atmosphere is a major planetary driving force. Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: I assume then that Ian also denies the existence of the ozone hole due to emissions of trace gases such as CFCs and HFCs? Do we really believe that one bellowing fan in a crowd of 85,000 at the MCG can completely change the course of a game? Mark Richardson Research Associate, Colorado State University/NASA JPL: The argument here is that something small doesn’t matter. Following its logic, then it must be safe to eat around 28 g (1 Oz) of hydrogen cyanide. Even though research has found that this is enough to kill dozens of people, the article’s logic says that there is no way something small can cause harm so eating hydrogen cyanide is fine. Victor Venema Scientist, University of Bonn, Germany: Do we really believe that one player in a stadium with an audience of 85,000 can make a difference? Naturally also small concentration can matter. Many substances are, for example, poisonous at much smaller concentrations. What matters is the amount of CO2. That there are also inert molecules in the atmosphere does not change the radiative influence of CO2. It is pretty amazing that Plimer states in this same article that “Over the past 30 years, planet Earth has greened due to a slight increase in atmospheric carbon dioxide.” Suddenly it is no problem that CO2 is a trace gas. For the past 4567 million years, the sun and the Earth’s orbit have driven climate change cycles. Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: Another logical fallacy. Just because orbital cycles controlled multi-millennial climate change in the past, that does not mean that anthropogenic emissions of greenhouse gases are not capable of altering the climate. In the past, the atmospheric carbon dioxide content has been orders of magnitude higher than now, yet there were ice ages Katrin Meissner Professor, University of New South Wales: This is a very bold (and wrong) statement. In the past 2 million years, CO2 has been lower than today and there were ice ages (glacials) when CO2 fell below a certain threshold. If we look further back, e.g. tens of millions of years, to periods of time when CO2 was higher than today (as in the Eocene), there was not much ice or snow around (if any)—certainly no ice age. If we go hundreds of millions of years back, the Sun was less strong than today. So yes, there might have been ice with higher CO2 concentrations and a faint Sun, but who knows? CO2 reconstructions do not go that far back. The current interglacial reached a peak about 5000 years ago. Twila Moon Research Scientist, University of Colorado, Boulder: This statement is misleading. Scientists do find evidence for warmer summers during a period roughly 5,000 years ago. However, these were also accompanied by colder winters in many places, and some places did not have warmer summers. The changes in climate at that time were the result of natural changes in Earth’s orbit. However, Earth’s orbit is not the cause of the warming over the last ~100 years. Since then, the planet has been cooling on a millennial scale Twila Moon Research Scientist, University of Colorado, Boulder: Here the author is muddling the issue of climate change by introducing time periods that are unrelated. Human-caused climate change via significant greenhouse gas emissions as discussed today only refers to the last roughly 100 years. This human activity has completely altered the Earth’s climate from any natural trend that may occur over 1,000s of years. The “millenial” scale is not relevant to the discussion of current human-caused climate change. Just 1.25 per cent of the carbon dioxide in the atmosphere-ocean system has been released by ­humans in the past 250 years. Mark Richardson Research Associate, Colorado State University/NASA JPL: About 100% of the increase in atmospheric carbon dioxide is due to humans. This is easy to show since 1980 using publicly available measurements. Nature emits and absorbs lots, but the net natural contribution over decades is close to zero*. Richardson (2013)Comment on “The phase relation between atmospheric carbon dioxide and global temperature” by Humlum, Stordahl and Solheim, Global and Planetary Change The ­atmospheric residency time of carbon dioxide is five years and it is quickly sequestered into plants, marine life, oceans and sediments. Katrin Meissner Professor, University of New South Wales: There are many papers that looked at the time it would take for natural negative feedbacks to remove the excess carbon from the atmosphere. It would take millennia*. Eby et al (2008)Lifetime of Anthropogenic Climate Change: Millennial Time Scales of Potential CO2 and Surface Temperature Perturbations, Journal of Climate Peter Landschützer Group Leader, Max Planck Institute for Meteorology: This statement of the “short residence time” has been misused in the past. This statement ignores the fact that there is a dynamic exchange between the atmosphere and the ocean. See e.g. Figure 6-01 in the IPCC 2013 report(copied below)—while the ocean indeed takes up about 80 billion metric tonnes of Carbon per year from the atmosphere, it also releases about 78 billion metric tonnes of Carbon per year back, hence CO2 molecules are not immediately sequestered as suggested by the author, but are subject to a dynamical exchange leaving the annual net sequestration to be on the order of 2 billion metric tonnes of Carbon per year, or only roughly 20-25 % of the annual human-caused CO2 emissions. This number is supported by models and measurements of the partial pressure of carbon dioxide in the ocean. Figure– Simplified schematic of the global carbon cycle. Source If human emissions of carbon dioxide drive global warming, why have there been slight warmings and coolings since the Industrial Revolution? Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: Because the Earth’s climate is not static and contains internal variability on time-scales from years to multiple decades. Volcanic eruptions can also alter the climate by injecting aerosols into the atmosphere which have a cooling effect. Richard Betts Professor, Met Office Hadley Centre & University of Exeter: Because there are other drivers of change too, such as aerosol particles that have an overall cooling effect. There is also internal climate variability. Nevertheless, the long-term warming is attributable to increasing greenhouse gas concentrations. Why is it that human emissions of carbon dioxide drive global warming yet natural emissions do not? Richard Betts Professor, Met Office Hadley Centre & University of Exeter: Nobody claims this, it is a strawman argument. Carbon dioxide is plant food. Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: Another non-sequitur. This is totally irrelevant to its role as a potent greenhouse gas. Without carbon dioxide, there would be no complex life on earth. It is neither pollution nor a poison, and in the past the atmospheric carbon dioxide content has varied enormously. Katrin Meissner Professor, University of New South Wales: This sentence is correct. But increasing CO2 above natural levels has an undeniable impact on climate. Biological, geological and planetary systems are extremely robust. Our evolving dynamic planet has survived sea level changes of hundreds of metres Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: This is a non-sequitur. Just because the physical Earth system still functions after major climatic changes, doesn’t mean that we as humans should not be concerned about its impacts on our civilization. Our evolving dynamic planet has survived sea level changes of hundreds of metres Victor Venema Scientist, University of Bonn, Germany: That is really nice for that rock revolving around the Sun. I personally also care about the people and communities living in coastal cities and towns and their cultural heritage. Ian Plimer can naturally have another opinion on their value. Richard Betts Professor, Met Office Hadley Centre & University of Exeter: The planet has survived these changes, but back then there were no humans around. Now we have many coastal cities, and populations of tens or even hundred of millions live within reach of sea level rises that have happened in previous warmer periods in Earth’s history. Our evolving dynamic planet has survived[…] mass extinctions Katrin Meissner Professor, University of New South Wales: The planet has survived mass extinctions, but many species (per definition) have not. It was never a question whether the planet itself will survive climate change. (It will!). Now the states rely on the weather and compete to reach the bottom. South Australia is winning: it has the most unreliable grid in the world outside Africa and the most expensive electricity. When South Australians buy electricity at $14,200/MWh, they are paying the equivalent of $400 a litre for petrol. Mark Diesendorf, Associate Professor, UNSW Sydney The comments about South Australia are misleading. SA has the same reliability as the rest of the Australian National Electricity Market. On average, SA has always had the highest electricity prices of the Australian states, long before wind power made a significant contribution, because of SA’s high dependence on high-priced natural gas. The growth of wind power has actually reduced the wholesale price of electricity in SA compared with what it would have been in the absence of wind. This is a consequence of the Merit Order Effect: wind and solar can bid into the grid at zero, or close to zero, price, because they have no fuel cost. The figure $14,200/MWh is grossly misleading. It’s the price during a rare peak in demand when supply was low. Similar high peak prices have occurred occasionally in the other states. It’s not typical of SA. Never mind that the emissions of carbon dioxide to make and maintain a wind or solar industrial complex are far greater than they will ever save. Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: This is completely incorrect. Australian emissions, comprising 1.3 per cent of global annual emissions, is dwarfed by annual increases of 2 per cent globally and 4 per cent by China. Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: Another misleading statement. All nations contributing less than 2% of emissions are, cumulatively, more important than India or China. It absolutely does matter that these nations reduce their emissions."
https://science.feedback.org/review/guardian-potential-future-hothouse-climate-generally-accurate-but-misstates-details-jonathan-watts/,1,"The Guardian, by Jonathan Watts, on 2018-08-07.",,"""Domino-effect of climate events could move Earth into a ‘hothouse’ state""",,,,,"This article in The Guardian covers an essay published by a group of scientists in The Proceedings of the National Academy of Sciences. The paper describes previously existing research but discusses the possibility that feedbacks could commit Earth’s climate to long-term warming even if human-caused emissions ceased. Scientists who reviewed the article found that it explained the article fairly accurately, with some subtle exceptions. The potential warming due to greenhouse gases released from permafrost, for example, is misstated as 0.9 °C—ten times the correct number of 0.09 °C. The article could also make it clearer for the reader that the essay relates to future warming that could take hundreds or even thousands of years to fully materialize.See all the scientists’ annotations in context. You can also install the Hypothesis browser extension to read the scientists’ annotations in context.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Andrew MacDougall Assistant Professor, St. Francis Xavier University: The article reasonably summarizes a new study published in PNAS, which describes the potential of tipping elements to enhance climate warming and the potential for the Earth to transition into a hot-house climate state. The article is careful to point out uncertainties and thus avoids being sensational. However, there are many small errors scattered throughout the article. For example, the strength of the permafrost carbon feedback is given as 0.9 °C instead of 0.09 (0.04 to 0.16) °C. Other examples include referring to Arctic sea-ice as the “Arctic ice sheet”, and attributing the permafrost feedback to release of methane instead of primarily a release of CO2. Richard Betts Professor, Met Office Hadley Centre & University of Exeter: The two important flaws in the article are that: 1) It does not make clear that the timescales involved in these feedbacks becoming large are very long—the paper says centuries to millennia. This is compounded by a mistake in one of the numbers quoted (permafrost feedback should be 0.09 °C by 2100 according to the paper, but the article writes this as 0.9 °C). 2) The article ramps up the certainty of the scenario, using “will” where the paper uses “could” in several places. Pepijn Bakker Assistant professor, Department of Earth Sciences, Vrije Universiteit, Netherlands: No inaccuracies and a good, balanced article with some notes on the uncertainties of the work in question, and remarks from scientists that were not involved in the paper. Katrin Meissner Professor, University of New South Wales: The article fairly represents the main conclusions of the PNAS paper. Alexis Berg Research Associate, Harvard University: This article does a decent job reporting on a recent scientific paper. Admittedly it’s a tricky article to report on. The original article in PNAS asks the question whether a “2°C warmer” climate will actually be there if we reduce CO2 emissions enough to be in line with such a warming target according to our current understanding of the climate system and to current climate model projections. The key distinction is that IPCC projections do suggest that for some emission trajectories, global mean temperature stabilizes at +2°C. However, certain feedback loops are not routinely accounted for in climate models yet (e.g., permafrost melting), and the time horizon of projections is usually limited to 2100 – certain feedbacks might kick in after that. So, the authors of the PNAS paper are saying: there is small possibility that +2°C is actually not stable and ultimately the system will slip away. However, there don’t really bring up any new evidence. It’s really more a discussion piece. I think the Guardian article could have done a slightly better job conveying the level of uncertainty of the PNAS paper and explaining the difference between the PNAS authors’ conjecture and current climate model projections. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Annotations: The statements quoted below are from the article; comments are from the reviewers (and are lightly edited for clarity). Domino-effect of climate events could move Earth into a ‘hothouse’ state Richard Betts Professor, Met Office Hadley Centre & University of Exeter: “Move into” makes it sound sudden, but the paper suggests that, although the feedbacks could be triggered soon and become self-perpetuating, they could take centuries to millennia to take full effect. More accurate content would warrant a revised title, eg “Domino-effect of climate events could set Earth on path towards a ‘hothouse’ state”. The authors of the essay, published in Proceedings of the National Academy of Sciences, stress their analysis is not conclusive Richard Betts Professor, Met Office Hadley Centre & University of Exeter: I think “not conclusive” is still too certain based on the actual level of confidence in the paper. I’d say “tentative” would reflect the paper more accurately. For example, the paper uses the term “risk averse approach” for the proposed 2°C threshold, and says “we cannot exclude the risk…”. It also use caveated language such as “could” and “may” a lot, and talk of “probability … difficult to quantify”. This grim prospect is sketched out in a journal paper that considers the combined consequences of 10 climate change processes, including the release of methane trapped in Siberian permafrost Andrew MacDougall Assistant Professor, St. Francis Xavier University: The permafrost carbon cycle feedback results from the decay of organic matter (remains of dead plants) previously frozen in permafrost soils. Carbon can be released either as CO2 or methane depending on the conditions of the soil, however the strength of the feedback, especially on long time-scales, is expected to come mostly from the release of CO2. Their new paper asks whether the planet’s temperature can stabilise at 2°C or whether it will gravitate towards a more extreme state. Richard Betts Professor, Met Office Hadley Centre & University of Exeter: My reading of the paper is that it’s the other way round—it asks whether it would stabilize at 2°C or *could* gravitate towards a more extreme state. The paper is clear that this is about risk, not certainty, and that the proposed 2°C threshold represents a “risk averse approach” Previous studies have shown that weakening carbon sinks will add 0.25°C, forest dieback will add 0.11°C, permafrost thaw will add 0.9°C and increased bacterial respiration will add 0.02°C. Richard Betts Professor, Met Office Hadley Centre & University of Exeter: The paper uses “could” not “will”. (See Table 1.) The paper also says 0.09°C [for additional warming caused by permafrost thaw] not 0.9°C We note that the Earth has never in its history had a quasi-stable state that is around 2C warmer than the preindustrial and suggest that there is substantial risk that the system, itself, will ‘want’ to continue warming because of all of these other processes – even if we stop emissions,” she said. “This implies not only reducing emissions but much more.” Katrin Meissner Professor, University of New South Wales: This can be refined to: A stable state with today’s CO2 concentrations (or higher) is not compatible with a 1.5-2°C warming above preindustrial levels. As stated in the supplementary material, “Current atmospheric CO2 concentration has already reached the lower bound of mid-Pliocene levels (Table S1), an eventual sea-level rise of up to 10 m or more is likely unless CO2 emissions are rapidly reduced and widespread CO2 removal from the atmosphere is deployed.” Mid-Pliocene temperature levels were likely higher than the Paris target. The heatwave we now have in Europe is not something that was expected with just 1C of warming Richard Betts Professor, Met Office Hadley Centre & University of Exeter: This may reflect his personal view, but I don’t think this statement reflects the views of the meteorological community. Climate change has probably made the heatwave hotter than it would have been, but I’ve not seen any analysis suggesting that the additional impact of climate change on the heatwave is larger than would be expected from the 1°C global warming that we’ve seen so far. […]but to state that 2C is a threshold we can’t pull back from is new, I think. I’m not sure what ‘evidence’ there is for this Richard Betts Professor, Met Office Hadley Centre & University of Exeter: I agree with this cautionary note—the paper bases the 2°C threshold on previous papers that themselves are reviews, and the paper says this is a “risk averse” approach."
https://science.feedback.org/review/president-trumps-claim-that-water-supply-policy-has-worsened-california-wildfires-is-baseless/,Inaccurate,"Twitter/X, Donald Trump, 2018-08-05",California wildfires are being magnified & made so much worse by the bad environmental laws which aren’t allowing massive amounts of readily available water to be properly utilized. It is being diverted into the Pacific Ocean.,,"Factually inaccurate: There is no connection between the management of California's surface water supply and wildfires. There is no restriction on the use of water to fight fires, and the dryness of wildlands depends solely on weather, as they are not irrigated.","California's wildfires are the result of hot, dry weather that has left the landscape dry and vulnerable to ignition. Wildlands are not irrigated, so water supply policy has no relation to wildfires. Climate trends have contributed to make fires more likely and more extreme in California, as have past fire-fighting practices. The continued development of land for homes and cities has also placed more buildings in areas of risk. You can see a deeper discussion of climate change's role in recent California fires here.",California wildfires are being magnified & made so much worse by the bad environmental laws which aren’t allowing massive amounts of readily available water to be properly utilized. It is being diverted into the Pacific Ocean. Must also tree clear to stop fire from spreading!,,"Eric Kennedy, Assistant Professor, York University: As CalFire has confirmed, water allocations are not influencing how wildfires are being fought in California. There’s enough access to water as it stands, and firefighters are effective in using a wide variety of other methods to augment water: chemical retardants, cutting fire breaks, and lighting backfires, among others. Wildfire has always been—and will always be—a part of North American landscapes, and our history is full of massive conflagrations all over the continent. Instead of water, other issues are far more important: where we build, how we build, how we prepare as individuals and communities, and how we improve our management approaches. Daniel Swain Climate Scientist, University of California, Los Angeles: There are a whole host of explicit and implicit assertions in this presidential statement that are problematic. But perhaps the most demonstrably false of these is the notion that California water policy is the cause of the present severe wildfire situation. California has recently been experiencing record-breaking warmth, and the legacy of long-term drought is still apparent across much of the state. Vegetation dryness has approached or reached record levels, which is a direct result of high temperatures and (to a lesser extent) low precipitation. The severity of the ongoing wildfire situation in California can be partly attributed to the long-term warming trend and subsequent extreme dryness of vegetation, as well as the increasing encroachment of urban development into high-risk wildfire zones and (in some places) the legacy of forest management practices over the past century. (See the papers in this thread.) Source Why is California water policy essentially irrelevant in this context? First, it’s unclear how water in rivers, lakes, and reservoirs would actually mitigate the vegetation dryness and risk of fire in regions far from these bodies of water. Second, firefighting agencies have virtually unlimited access to existing surface water supplies, and firefighting helicopters and “super scooper” planes have been utilizing just about every available water source in the ongoing firefight (from natural lakes to rivers to man-made reservoirs). CalFire has made it clear that a lack of water for firefighting purposes is not the problem—instead, the agency is struggling to cope with the unusually high number of very large fires and the extreme behavior/rapid rates of spread of those fires currently burning."
https://science.feedback.org/review/washington-post-story-puts-recent-weather-extremes-in-accurate-climate-change-context-joel-achenbach-angela-fritz/,1.7,"The Washington Post, by Angela Fritz, Joel Achenbach, on 2018-07-26.",,"""Climate change is supercharging a hot and dangerous summer""",,,,,"This story in The Washington Post lists a variety of extreme weather events seen around the Northern Hemisphere recently. The article explains that some of these types of weather are known to be connected to human-caused climate trends. Scientists who reviewed the article found that this scientific context was accurately provided. Heatwaves and intense rainstorms, for example, are increasing in severity and frequency. Some weather patterns—like slow-moving meanders in the jet stream—are indeed less clear and consequently subjects of active research.See all the scientists’ annotations in context.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Daniel Swain Climate Scientist, University of California, Los Angeles: This article accurately describes the broader climate context of recent heat extremes throughout the Northern Hemisphere. There are a couple spots where specific claims are somewhat stronger than justified by the existing scientific evidence, but in general the piece gives an accurate impression regarding the role of climate change and recent advances in extreme event attribution science. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from the article; comments are from the reviewers (and are lightly edited for clarity). Climate change is supercharging a hot and dangerous summer Daniel Swain Climate Scientist, University of California, Los Angeles: This is a reasonable title for the piece. While climate change is not the only factor in recent extreme and record-breaking heat, it is an important and pervasive one. The notion that climate change is “supercharging” heat extremes is an accurate one. The brutal weather has been supercharged by human-induced climate change, scientists say. Climate models for three decades have predicted exactly what the world is seeing this summer. And they predict that it will get hotter — and that what is a record today could someday be the norm. Daniel Swain Climate Scientist, University of California, Los Angeles: Both of these statements are correct, and collectively emphasize two important points. First, the increasing frequency and intensity of heat extremes does indeed validate model-based and theoretical predictions from decades ago. Second, those same climate models suggest that what is today an extraordinary heat event could indeed become a “typical” temperature in future summers, depending on how much additional carbon society emits in the coming decades. Jennifer Francis Senior Scientist, Woods Hole Research Center: True. More intense and prolonged heatwaves are directly connected to global warming. Heavier precipitation events are linked with additional water vapor in the atmosphere, which results from higher air temperatures (warmer air can hold more water vapor) and greater evaporation from ocean and land. Longer, more intense droughts are also clearly connected to global warming, as higher temperatures dry out soils earlier in spring and allow them to heat up faster. Climate models have long predicted a general increase in these extremes, and now we can refine those predictions for particular types of events, regions, seasons, and varying background conditions (such as El Niño). Peter Gibson, Postdoctoral researcher, California Institute of Technology: This is mostly correct. Regarding what models have predicted—it’s certainly the case that climate models have predicted a general increase in the frequency of heat waves as the world warms and there is a strong human influence. What is rather unique about this particular heat wave has been the spatial extent across the Northern Hemisphere. Basic statistics tells us that in a warming world the general likelihood of heatwaves coinciding at multiple locations would also increase (all else being equal). But another important piece of this puzzle is the particular jet stream configuration that also essentially acts to connect the heatwaves in multiple different regions together. An active area of research is understanding and improving how well some of these important mechanisms are represented in climate models. It’s not just heat. A warming world is prone to multiple types of extreme weather — heavier downpours, stronger hurricanes, longer droughts. Daniel Swain Climate Scientist, University of California, Los Angeles: There is indeed scientific evidence that each of these types of extreme events is increasing (or will increase) in a warming world. However, the evidence is strongest for heatwaves and heavy downpours. The proximate cause of the Northern Hemisphere bake-off is the unusual behavior of the jet stream, a wavy track of west-to-east-prevailing wind at high altitude. The jet stream controls broad weather patterns, such as high-pressure and low-pressure systems. The extent of climate change’s influence on the jet stream is an intense subject of research. Daniel Swain Climate Scientist, University of California, Los Angeles: This is accurate. So-called “atmospheric blocking” has occurred frequently this summer, and has historically been associated with extreme temperature and precipitation events. Jennifer Francis Senior Scientist, Woods Hole Research Center: Also true. Many factors affect the jet stream’s strength and path, and recent studies are revealing several mechanisms by which climate change is playing a role. This summer the jet stream has undulated far north and south, and those large waves tend to remain locked in place for weeks, causing persistent weather patterns of various sorts. It’s no coincidence that severe heatwaves have occurred simultaneously in several locations (Japan, SW U.S., Greece, Scandinavia, Alaska) together with flooding in other locations and even cooler-than-normal temperatures elsewhere. Peter Gibson, Postdoctoral researcher, California Institute of Technology: This is an accurate reflection of where the science is at. I would point out that even if human fingerprints aren’t all over the dynamics of this event (i.e., the particular jet stream configuration) we know already that human fingerprints are all over the thermodynamics (i.e., the heatwave formed in an environment notably warmer than it would have been in the absence of human influence on the climate system). Last year, scientists published evidence that the conditions leading up to “stuck jet streams” are becoming more common, with warming in the Arctic seen as a likely culprit. Daniel Swain Climate Scientist, University of California, Los Angeles: There have indeed been several recent publications suggesting that certain high-amplitude jet stream patterns have been occurring more frequently in recent years. There are also some hints that this could be related to enhanced high-latitude warming, but the potential causal linkages remain the subject of considerable ongoing scientific debate. At this point, there’s not yet consensus that the Arctic is a “likely” culprit, although it certainly is a suspect. Gone are the days when scientists drew a bright line dividing weather and climate. Now researchers can examine a weather event and estimate how much climate change had to do with causing or exacerbating it. Daniel Swain Climate Scientist, University of California, Los Angeles: The field of “extreme event attribution” has indeed become much more prominent in recent years. This is a result of a combination of better modeling and analysis tools, plus a longer period of observed climate data from which to draw conclusions. While it is not possible to make these kind of attribution claims for all types of extreme weather events, it is increasingly true that this has moved from the margins to the relative mainstream of climate science. Jennifer Francis Senior Scientist, Woods Hole Research Center: True, but perhaps a bit optimistic. In some cases the influence of climate change on a particular weather event can be estimated fairly well, but many times the extent of attribution is difficult to pin down. That said, scientists can now state much more confidently that certain types of extreme events are more or less likely now than in pre-industrial times, and often the amount of climate-related change can be quantified (e.g. twice as likely). Peter Gibson, Postdoctoral researcher, California Institute of Technology: This refers to event attribution (an important and growing subfield of climate science)—but it’s not always easy and there are some subtleties to this worth pointing out. Certainly, we can (and do) do this well for heatwaves, but it is still a major challenge for other types of extreme weather events today. Basically, events where the relevant physics need to be resolved at very high resolution (e.g. tornadoes and other very localized convective storms) are a major challenge for current day climate models used in these types of attribution studies. But our models are improving all the time so what is in the “hard basket” is constantly changing. Overall precipitation has decreased in the South and West and increased in the North and East. That trend will continue.Daniel Swain Climate Scientist, University of California, Los Angeles: This statement is overly broad. Attribution of regional mean precipitation trends is still a challenging task in most places, with some exceptions. The heaviest precipitation events will become more frequent and more extreme. Snowpack will continue to decline. Large wildfires will become even more frequent. Daniel Swain Climate Scientist, University of California, Los Angeles: These statements have much more robust support than the previous one."
https://science.feedback.org/review/npr-story-accurately-describes-ecological-consequences-of-altered-spring-timings-in-a-warming-climate-nathan-rott/,1.5,"NPR, by Nathan Rott, on 2018-07-23.",,"""Spring Is Springing Sooner, Throwing Nature's Rhythms Out Of Whack""",,,,,"This article at NPR discusses what happens when warm spring weather arrives earlier because of climate change. Animals must adjust to changes in the timing of plant flowering, for example, leading to noticeable desynchrony in the ecosystem, e.g. “Flowers are blooming before there are bees to pollinate them. Hard frosts are still occurring long after winter’s snow melts away, decimating fruit orchards and budding plants.” Scientists who reviewed the story found that it accurately represented trends in data and research on the topic. They found only a few statements that could be improved, such as referencing snowpack in April rather than January to better relate to spring conditions.See all the scientists’ annotations in context.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Dasvinder Kambo PhD Candidate, Queen's University: I believe that the article is well written and it is mostly supported by the evidence. However, there were a few places where I believe the evidence was not as strong for the given statement. Mark Eakin Scientist, Coordinator of NOAA’s Coral Reef Watch, National Oceanic and Atmospheric Administration: Really more like a 1.9 rating [than 2.0] because they should have quoted the April snowpack data, not January. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Annotations: The statements quoted below are from the article; comments are from the reviewers (and are lightly edited for clarity). In Alaska, brown bears are changing their feeding habits to eat elderberries that ripen earlier. Dasvinder Kambo PhD Candidate, Queen's University: This was a good paper they cited*. It clearly demonstrated a shift from hunting salmon to elderberry, which fruits earlier. Deacy et al (2017)Phenological synchronization disrupts trophic interactions between Kodiak brown bears and salmon, PNAS “The April low temperatures here are now about 6 degrees Fahrenheit warmer than they used to be.” Dasvinder Kambo PhD Candidate, Queen's University: High altitude sites are warming at especially high speeds. Colorado’s snowpack this year was the worst it had been in . Mark Eakin Scientist, Coordinator of NOAA’s Coral Reef Watch, National Oceanic and Atmospheric Administration: This statement cites the January snowpack. The April snowpack is the measure of peak snowpack at the end of the season. It should have quoted this story, instead. The conclusion would have been similar but not the “more than 30 years” figure. “We have less flowers.” Dasvinder Kambo PhD Candidate, Queen's University: Would be nice to have species listed here. Purely because in some cases it’s not whether flowers are ‘fewer’, but rather their flowering time has been altered. Species that have a lot of plasticity tend to be generalists. Dasvinder Kambo PhD Candidate, Queen's University: While this statement is true on a theoretical level, I’m not sure the appropriate research has been done on a large scale in alpine ecosystems. And there is a lot of evidence that climate change is diminishing biodiversity, which can be seen in these alpine meadows as well. Dasvinder Kambo PhD Candidate, Queen's University: Not an adequate reference (linked) for such a strong claim. I recommend incorporating the following paper: Vellend et al. (2013)Global meta-analysis reveals no net change in local-scale plant biodiversity over time, PNAS"
https://science.feedback.org/review/fred-singer-incorrectly-claims-sea-level-rise-is-not-caused-by-climate-change/,Incorrect,"The Wall Street Journal, Fred Singer, 2018-05-15","Sea-level rise does not seem to depend on ocean temperature, and certainly not on CO2",,Flawed Reasoning: Singer cherry-picks an arbitrary time period (1915-1945) and a single estimate of sea level rise published 28 years ago to inaccurately claim that sea level rise has not accelerated. He then incorrectly concludes that this means global temperature does not affect sea level rise.,"Global sea level has risen significantly over the last century, and at an accelerating rate. Multiple lines of evidence clearly demonstrate that this is largely due to the expansion of warming seawater (an inescapable consequence of the laws of physics) and the melting of glacial ice on land.","Currently, sea-level rise does not seem to depend on ocean temperature, and certainly not on CO2. We can expect the sea to continue rising at about the present rate for the foreseeable future.",,"Fred Singer’s opinion is based entirely on a cherry-picked comparison of sea level rise between 1915 and 1945 and a single study published in 1990, claiming a lack of accelerating sea level rise despite continued warming. But in fact, modern research utilizing all available data clearly indicates that sea level rise has accelerated, and is unambiguously the result of human-caused global warming. Since the 1990s for example, satellites have measured an acceleration in the rate of global sea level rise: Figure – Global mean sea level (blue), after removing an estimate for the impacts of the eruption of Mount Pinatubo (red), and after also removing the influence of El Niño (green), fit with a quadratic (black).FromNerem et al. (2018) The latest IPCC report summarized scientists’ understanding of the factors responsible for sea level rise: “Ocean thermal expansion and glacier melting have been the dominant contributors to 20th century global mean sea level rise. Observations since 1971 indicate that thermal expansion and glaciers (excluding Antarctic glaciers peripheral to the ice sheet) explain 75% of the observed rise (high confidence). The contribution of the Greenland and Antarctic ice sheets has increased since the early 1990s, partly from increased outflow induced by warming of the immediately adjacent ocean. Natural and human-induced land water storage changes have made only a small contribution; the rate of groundwater depletion has increased and now exceeds the rate of reservoir impoundment. Since 1993, when observations of all sea level components are available, the sum of contributions equals the observed global mean sea level rise within uncertainties (high confidence).” Chris Roberts Research Scientist, ECMWF/Met Office: This claim severely misrepresents the scientific understanding of the processes responsible for observed changes in global sea level. Understanding and attributing the causes of changes in global sea level is an area of active research and there are genuine uncertainties, but there is a clear consensus on the important roles for ocean thermal expansion and addition of mass to the oceans from melting glaciers and ice caps during recent decades. For example, the following paper by Church et al. (2008)* summarizes the independent lines of evidence for changes in sea level from satellite altimeter and tide gauge measurements and how these changes can be explained by a combination of thermal expansion and exchange of mass (either liquid water or ice) between the oceans and continents: Figure – Global sea‐level budget from 1961 to 2008. (left) The observed sea level using coastal and island tide gauges (solid black line with grey shading indicating the estimated uncertainty) and using satellite altimeter data (dashed black line) with thermal expansion and glaciers melting components; terrestrial storage (e.g. dams) partially offsets other contributions to sea‐level rise. (right) The observed sea level and the sum of components. Church et al (2011) Revisiting the Earth’s sea‐level and energy budgets from 1961 to 2008, Geophysical Research Letters Stefan Rahmstorf Professor, Potsdam University: This claim is against the basic laws of physics—warming causes thermal expansion of sea water and thereby sea-level rise, full stop. This is true regardless of whether this effect can be detected in a cherry-picked short time interval with poor data quality. There is a clear relationship between the accelerating rate of sea-level rise and the increasing global temperature, which is shown in this post(including the figure below). Adapted from Rahmstorf (2007) "
https://science.feedback.org/review/usa-today-paleoclimate-study-mostly-accurate-lacks-clarity-doyle-rice/,0.8,"USA Today, by Doyle Rice, on 2018-07-06.",,"""Global warming could be far worse than predicted, new study suggests""",,,,,"This story in USA Today covers a new study that compared past climate changes to model simulations, concluding that models can underestimate future warming over thousands of years. Scientists who reviewed the article found that it described the study accurately. However, it implies relevance for projections of future climate change without making it clear to readers that this refers to projections far beyond the end of this century. The study does not indicate that the oft-discussed climate model projections of warming by 2100 are underestimated—an important distinction.See all the scientists’ annotations in context REVIEWERS’ OVERALL FEEDBACK: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: This article accurately articulates how studying past climates as an analogue for present day warming can show how we may be underestimating the long-term equilibrium temperature rise of the planet. The only thing missing is an extra sentence or two detailing the reason for the discrepancies between models and observations and a clearer expression of the time-scales considered (end of century vs millennia from now). Kelly McCusker Research Associate, Rhodium Group and Climate Impact Lab: The article is accurate but could be improved with additional context, in particular emphasizing that the timescale over which the listed changes could occur is centuries-to-millennia. Irene Brox Nilsen Researcher, Norwegian Water Resources and Energy Directorate: I think the text accurately represents the current status of knowledge on projected climate change. Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: This article presents analysis from a scientific review article that uses past Earth climates as an analogue for future climate change. Although the article does not contain major inaccuracies, some of the discussion deserves more context to ensure that readers are not misled. Mark Richardson Research Associate, Colorado State University/NASA JPL: An accurate and balanced article that gives readers a good flavour of the research but the reference to “Earth’s history” might confuse some when it otherwise refers to the studied period: the past 3.5 million years. Neatly explains a lot of the key points in a small word count, but I would have liked a sentence to emphasise that this reviews a lot of other work so it isn’t a shocking outlier result but is likely a reliable representation of current understanding. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Annotations: The statements quoted below are from the article; comments and replies are from the reviewers. Collapsing polar ice caps, a green Sahara Desert, a 20-foot sea-level rise. That’s the potential future of Earth Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: Although background on the underlying research is provided further down, it is important to put this information into the context of the original study to give a sense of timescale and uncertainty. The underlying study reviews the paleoclimate record and finds periods in which the Earth’s climate may serve as an analogue for the future. The authors note that the Earth, with increased atmospheric carbon dioxide and a warmer global temperatures, exhibited reductions in ice at the poles, savanna expanded into the region where the Sahara desert currently exists, and sea levels were higher. It’s important to keep in mind a few points: drastic changes (e.g. 20-foot sea-level rise) are expected to occur over long timescales (i.e., not in our lifetime) these past climate analogues don’t exactly match our current situation (Earth’s orbit, for example); so we should not expect that the past is a perfect predictor of the future the magnitude of these changes does depend on human actions over the next century (i.e.., how much carbon dioxide will we emit?) global warming could be twice as warm as current climate models predict. Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: The study suggests this is an upper bound. This is important, since this seems to be a factor motivating the attention-grabbing headline. From the study: “model-based climate projections may underestimate long-term warming in response to future radiative forcing by as much as a factor of two” and “models may underestimate observed polar amplification and global mean temperatures of past warm climate states by up to a factor of two on millennial timescales”. This “factor of two” is also derived using model simulations of large increases of CO2 (~4x pre-industrial levels) and comparing the model simulated warming to paleoclimate data from the early Eocene climatic optimum, which was roughly 50 million years ago. During this time, the Earth’s continental configuration (land mass locations and elevation) differed from the present and these continental configuration differences were not reflected in this model/paleo-data comparison. When the authors account for this, the differences between the models and the paleoclimate record appear to be substantially reduced. This “factor of two” seems to arise in part due to an apples-to-oranges comparison. Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: This is slightly misleading and warrants some clarification. There is a difference between the typical warming we think of with regards to IPCC targets (i.e., 2°C by 2100), which considers the next several decades and equilibrium climate sensitivity, which will take millennia to reach and involves slow processes such as ice sheet dynamics and aspects of the carbon cycle. This study deals with the latter. current climate predictions may underestimate long-term warming by as much as a factor of two Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: I would have liked the article to include, specifically, the time-scale as stated in the paper. Namely, that this is only true on millennial timescales. The rate of warming is also remarkable: “The changes we see today are much faster than anything encountered in Earth’s history…” Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: An example of this (over the last 65 million years) is noted in this study*. Diffenbaugh and Field (2013) Changes in Ecologically Critical Terrestrial Climate Conditions, Science This could mean the landmark Paris Climate Agreement – which seeks to limit global warming to 2 degrees Celsius (3.6 degrees Fahrenheit) above pre-industrial levels – may not be enough to ward off catastrophe. Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: This paragraph is well-qualified by the author quotes in the subsequent paragraphs and the conclusion from the original study: “…we can conclude that even for a 2°C (and potentially 1.5°C) global warming – as targeted in the Paris Agreement – significant impacts on the Earth sustem are to be expected. In looking at Earth’s past, scientists can predict what the future will look like Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: Somewhere in here, it should be noted that the past is not expected to be a perfect predictor of the future (or at least give some sense of the uncertainties involved in this research). The periods considered in the original study had important differences relative to the current Earth: different Earth-sun orbits, continental configurations, and land ice, for example. These differences affect the Earth’s climate response to greenhouse gases. Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: This is true, but it should be clarified that past warming events are not perfect analogues for current warming and that there is a growing body of research currently being done on the state-dependence of climate sensitivity. Human-inflicted climate change is caused by the burning of fossil fuels such as coal, oil and gas, which release heat-trapping greenhouse gases such as carbon dioxide and methane into the the atmosphere. Mark Richardson Research Associate, Colorado State University/NASA JPL: This is a fair statement of the scientific understanding. I applaud the author for sticking to credible scientific findings rather than opinions from bloggers or PR sheets produced by political think tanks. But as the change gets larger or more persistent … it appears they underestimate climate change Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: This is an important point: that the potential discrepancies between models and paleoclimate data are mainly for large increases in carbon dioxide (and warming). The research also revealed how large areas of the polar ice caps could collapse and significant changes to ecosystems could see the Sahara Desert become green and the edges of tropical forests turn into fire-dominated savanna. Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: This paragraph is more appropriately caveated (using the word “could” and “large areas” and “edges”) in comparison to the leading sentence, “collapsing polar ice caps,” which is a little less clear. A useful way to frame this information would be that: past climate have seen these profound changes and it is plausible that the future may look similar. “we cannot comment on how far in the future these changes will occur.” Mark Richardson Research Associate, Colorado State University/NASA JPL: This is an important caveat. Meissner phrases it well and Rice deciding to include it was a good choice. lead author Fischer said that without serious reduction in carbon dioxide emissions, there is “very little margin for error to meet the Paris targets.” Mark Richardson Research Associate, Colorado State University/NASA JPL: This is a fair summary of the necessary policy response to have a good chance of expecting we could hit the Paris targets. It also avoids making a value judgment on the Paris Agreement and the scientists stick to technical issues. Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: A point that is not made often enough. Even with drastic cuts to carbon emissions, this still only gives us a moderate chance* of keeping warming under 2 degrees C. Raftery et al (2017) Less than 2 °C warming by 2100 unlikely, Nature Climate Change Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: This is a good point to make: research* indicates that there is a non-negligible chance we have already emitted sufficient greenhouse gases to commit the Earth to 1.5 degrees C of warming. Mauritsen and Pincus (2017) Committed warming inferred from observations, Nature Climate Change"
https://science.feedback.org/review/financial-post-commentary-misleads-warming-effect-greenhouse-gas-emissions-cherry-picking-studies-ross-mckitrick/,-1,"Financial Post, by Ross McKitrick, on 2018-06-20.",,"""Ross McKitrick: All those warming-climate predictions suddenly have a big, new problem""",,,,,"This opinion published by the Financial Post, written by economist Ross McKitrick, claims that Earth’s climate is much less sensitive to additions of greenhouse gases like carbon dioxide than climate scientists think. The article further claims that global warming is, therefore, not an important problem—and may even be beneficial. Scientists who reviewed the article found that this argument is misleading, and relies on ignoring all but a select few of the many studies that exist on this topic. These studies use a particular method for estimating this “equilibrium climate sensitivity” that other research has shown to be problematic. An informed opinion should consider all the scientific lines of evidence available instead of picking the ones that agree with the author’s predetermined conclusion. Taken together, that evidence does not support the article’s argument. For a detailed summary of what we know about Earth’s equilibrium climate sensitivity, see this article at Carbon Brief.See all the scientists’ annotations in context REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Reto Knutti Professor, ETH Zürich: This is an opinion piece in the “lukewarm” category, arguing that climate models are wrong, future warming will be small, based on carefully selected publications, misleading presentation, and incorrect reporting of the underlying data. This opinion piece is a completely one-sided and misleading representation of what we know about the long-term response of temperature to greenhouses gases. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: This article selectively cherry-picks studies showing low climate sensitivity, leaving out whole lines of evidence (e.g. paleoclimate studies) that agree with the sensitivity estimates found in models. It also glosses over the many criticisms of instrumentally based (or “energy balance”) sensitivity estimates published in recent years. Patrick Brown Assistant Professor, San Jose State University: The article makes a big deal about the fact that some methods of estimating equilibrium climate sensitivity tend to give smaller results than others. This is not a new finding and it is not under appreciated in the climate science literature or by the IPCC. The methods for estimating climate sensitivity discussed in the article are already incorporated into the uncertainty ranges of climate sensitivity considered by the IPCC and other assessments. Overall, it is best practice to consider results from a full range of methods and to not focus on the single method that produces the lowest estimate of climate sensitivity. Mark Zelinka Research Scientist, Lawrence Livermore National Laboratory: Rather than present the Lewis and Curry (2018) study in the context of the multitude of other estimates of equilibrium climate sensitivity, the article shows only results from studies using similar approaches that confirm the claim in the title. Such energy budget approaches consistently underestimate climate sensitivity primarily because they rely on a conceptual model of forcing and response that is too simple for the problem at hand, as an explosion of recent literature on the topic has shown. This body of evidence is either dismissed out of hand or ignored entirely in the article. Andrew Dessler Professor, Texas A&M University: This paper misrepresents that state of science. It selectively quotes analyses that support the author’s opinion, while ignoring all contrary evidence. Putting all of the evidence together, there’s no reason to think that climate models are wrong. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Annotations: The statements quoted below are from the article; comments and replies are from the reviewers. People who study the impacts of global warming have found that if ECS is low — say, less than two — then the impacts of global warming on the economy will be mostly small and, in many places, mildly beneficial. If it is very low, for instance around one, it means greenhouse gas emissions are simply not worth doing anything about. Patrick Brown Assistant Professor, San Jose State University: This passage is misleading. It seems to imply that society has already decided to exactly double CO2 concentrations and has committed to emitting no further greenhouse gasses after that. If that were the case, then we could in fact assess climate change impacts in the manner done here. However, society is far from committing to stabilizing CO2 concentrations at “only” twice their preindustrial levels. We may go well beyond that. In that case, lower equilibrium climate sensitivity just means that it takes longer to reach a given level of warming. So even if climate sensitivity turns out to be very low, all the worst impacts could still be realized—they would just be delayed. We may not be able to stop it, but we’d better get ready to adapt to it. Patrick Brown Assistant Professor, San Jose State University: The magnitude of equilibrium climate sensitivity has nothing to do with whether or not we can stop climate change. Global temperatures will stabilize when the atmospheric concentrations of greenhouse gasses stabilize. So regardless of the climate sensitivity value, we can “stop” climate change by stabilizing greenhouse gas concentrations. Their ECS estimate is 1.5 degrees, with a probability range between 1.05 and 2.45 degrees. Reto Knutti Professor, ETH Zürich: The opinion piece claims that Lewis and Curry account for changes in feedback and incomplete observational coverage, yet quotes the range that does not! The range that does include those effects has a median of 1.76 K (5−95%: 1.2−3.1 K). Whether this is deliberate or an oversight is hard to know, but it certainly does not add to the credibility of the piece. But it is part of a long list of studies from independent teams (as this interactive graphic shows), using a variety of methods that take account of critical challenges, all of which conclude that climate models exhibit too much sensitivity to greenhouse gases. Andrew Dessler Professor, Texas A&M University: While several groups have indeed done this calculation, and they all get the same answer, these groups are basically doing versions of the same calculation with the same data. Thus, their agreement means much, much less than is suggested here. If there is a problem with the methodology, which several recently published papers have suggested, then all of them are wrong. Reto Knutti Professor, ETH Zürich: The text refers to a “long list of studies from independent teams“ using “a variety of methods”, but effectively they are all doing the same thing: relating forcing and ocean heat uptake to the observed warming. Dozens of other studies have demonstrated that the simple energy balance models provide climate sensitivity estimates that are too low1,2. The study by Lewis and Curry claims to account for that, but the effects could be much bigger3. The text fails to discuss that there are literally hundreds of studies about climate sensitivity. We refer to over 400 in our review2. Taken together, they do show a substantial uncertainty range, but they do not support the “lukewarm” position. And there is no evidence that estimates of climate sensitivity have decreased recently. 1-Knutti and Rugenstein (2015) Feedbacks, climate sensitivity and the limits of linear models, Philosophical Transactions of the Royal Society, A 2-Knutti et al (2017) Beyond equilibrium climate sensitivity, Nature Geoscience 3-Gregory and Andrews (2016) Variation in climate sensitivity and feedback parameters during the historical period, Geophysical Research Letters Mark Zelinka Research Scientist, Lawrence Livermore National Laboratory: Cherry pick much? For a better perspective, refer to the recent comprehensive literature review by Knutti et al*, which shows ECS estimates from a wide range of methodologies (see figures below). Notably, energy budget estimates are consistently biased low relative to other lines of evidence. Knutti et al (2017) Beyond equilibrium climate sensitivity, Nature Geoscience Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: This is only true if you selectively pick studies with low sensitivity. We recently looked at all climate sensitivity studies published using all different methods and found no evidence of an overall decline in estimated ECS in recent years: People who study the impacts of global warming have found that if ECS is low — say, less than two — then the impacts of global warming on the economy will be mostly small and, in many places, mildly beneficial. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: This is not necessarily true, as the amount of future warming depends as much on future emissions trajectories as it does on climate sensitivity. A world with 1000 ppm CO2 and an equilibrium climate sensitivity of 2 would still be quite unpleasant. A well-known statistical distribution derived from modeling studies summarizes the uncertainties in this method. It shows that ECS is probably between two and 4.5 degrees, possibly as low as 1.5 but not lower, and possibly as high as nine degrees. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: This is not particularly accurate. Virtually no model-based approaches yield equilibrium climate sensitivity estimates below 2 °C, and few yield estimates much above 5 °C. See Knutti et al* for a summary of climate sensitivity studies broken out by study type. Knutti et al (2017) Beyond equilibrium climate sensitivity, Nature Geoscience Reto Knutti Professor, ETH Zürich: Uncertainty is not our friend. The fact that the different methods and studies do not fully agree should not be taken as an argument to pick one particular number that one happens to like and discard all the other evidence. As an analogy, when suddenly fog appears on a narrow windy road and the obstacles are hard to see, the normal reaction would be to slow down to be on the safe side, not to accelerate. Greater uncertainty in future warming should be an argument to prepare for the worst case, not to hope for the unlikely case that the impacts will be benign. The surprising thing is that the Energy Balance estimates are very low compared to model-based estimates. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: While on average Energy Balance-based approaches (or “instrumental” approaches) tend to give a lower sensitivity than model or paleoclimate results, not all do. See the figure below from Carbon Brief’s recent climate sensitivity explainer, which looks at 143 studies on equilibrium climate sensitivity between 2000 and present: McKitrick also completely ignores all the climate sensitivity evidence from studies of the Earth’s past climate changes (Paleoclimate), which broadly agrees with the equilibrium climate sensitivity range from climate models. Reto Knutti Professor, ETH Zürich: The text implies that one way to estimate equilibrium climate sensitivity is by using climate models, the other is by using the observed energy budget, and of course the “observed” is claimed to be better. The author fails to understand or convey that there is no way to “observe” climate sensitivity, and all estimates are using a model of some sort, and all models are constrained and evaluated by observations. The energy balance method assumes a simple energy balance framework where feedbacks are independent of timescale, forcing magnitude, and forcing type, which we know is a simplification. In addition is uses radiative forcing as an input that is model derived. It is not obvious that one method is better than the other, but it is clear that all are based on models and observations combined. Climate modelers have put forward two explanations for the discrepancy. One is called the “emergent constraint” approach. The idea is that models yield a range of ECS values, and while we can’t measure ECS directly, the models also yield estimates of a lot of other things that we can measure (such as the reflectivity of cloud tops), so we could compare those other measures to the data, and when we do, sometimes the models with high ECS values also yield measures of secondary things that fit the data better than models with low ECS values. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: McKitrick is a bit confused on this point; emergent constraints are useful to narrow down the range of estimates between models, but are not intended to reconcile energy balance/instrumental approaches with other lines of evidence. Rather, scientists have focused on a number of different shortcomings of instrumental-based equilibrium climate sensitivity estimates. These include using different surface temperature fields (e.g. models use air over oceans, while observations use sea surface temperatures), incomplete data (observations are missing data in much of the Arctic), timescales of feedbacks (instrumental climate sensitivity estimates assume inferred feedbacks over the past few decades remain constant over time, while models show greater feedback magnitudes in the future than in the past), and many other issues. For a summary of these studies see our recent Carbon Brief explainer. If ECS is as low as the Energy Balance literature suggests, it means that the climate models we have been using for decades run too hot and need to be revised. Reto Knutti Professor, ETH Zürich: The text implies that the models are running too hot. From the period where we have observations, that is simply not correct, the observed warming is within the model range."
https://science.feedback.org/review/washington-post-article-accurately-describes-latest-estimate-accelerating-antarctic-ice-loss-chris-mooney/,1.3,"The Washington Post, by Chris Mooney, on 2018-06-13.",,"""Antarctic ice loss has tripled in a decade. If that continues, we are in serious trouble.""",,,,,"This article in The Washington Post describes an important study from a project called the Ice sheet Mass Balance Intercomparison Exercise (or IMBIE), which synthesized many existing records of Antarctic ice based on different types of measurements. The resulting estimate shows that Antarctica alone lost enough ice between 1992 and 2017 to raise global sea level by around 7.6 millimeters—almost 10% of the total sea level change over that time period. Scientists who reviewed the article found that it accurately summarized this result, while explaining some of the processes behind this mass loss and the sea level rise it produces. However, they note that future trends depend partly on complex natural variability, which the article could have made clear.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Thomas Frederikse Postdoctoral researcher, Jet Propulsion Laboratory/California Institute of Technology: The article accurately summarises the main conclusions of the discussed study, and multiple experts give a clear overview of the current knowledge of the fate of the Antarctic ice sheet and associated sea level rise under global warming. Peter Neff Assistant Research Professor, University of Minnesota: Chris Mooney’s article on recent Antarctic ice mass loss results faithfully reports on the new data, providing a wealth of useful information to the reader. However, a lack of exploration of the causes of this Antarctic ice mass loss leaves the article vulnerable to being wrongly filed under “one more depressing impact of human-caused climate change” when the true story is more complex. From the article’s title, Mooney would have done well to address what processes, in addition to continued atmospheric warming, may cause continued Antarctic ice mass loss. Anna Hughes Lecturer, University of Manchester: The article presents the results of the study accurately, and uses multiple comments from scientists both involved and not-involved in the study to highlight the key findings. Some of the explanations are simplified, and there is a slight attempt at the end to downplay the results by suggesting scientists can’t predict the future. It is correct that the study presented is not making predictions, rather documenting past changes, but the positive trend is what we would expect based on the longer record of change we have for glaciers and ice caps. Aimée Slangen Researcher, Royal Netherlands Institute for Sea Research (NIOZ): An informative article citing relevant experts, and a good explainer of the findings of the IMBIE study. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from the article; comments and replies are from the reviewers. 1.The loss of Antarctic ice has accelerated over the last 25 years. The future outlook is complicated, depending on both natural processes and human activity, but could result in large contributions to global sea level rise. “Antarctica’s ice sheet is melting at a rapidly increasing rate, now pouring more than 200 billion tons of ice into the ocean annually and raising sea levels a half millimeter every year, a team of 80 scientists reported Wednesday.” Peter Neff Assistant Research Professor, University of Minnesota: If these numbers seem abstract, consider this: Much of the ice mass loss is focused along the Amundsen Sea coast of West Antarctica. This is essentially the Pacific Coast of West Antarctica, which is roughly the same length as the Pacific Coast of the United States (~1200 miles, 1900 kilometers). The two Pacific Coasts—of the USA and the Antarctic—are overlain in this NASA image: Source: NASA Basically, this entire Pacific coast of West Antarctica is where Antarctic ice mass loss comes from, as can be seen in this animation of GRACE satellite gravity measurements from 2002-2016 which were part of the IMBIE study. In this illustration you can also see a “hot-spot” of mass loss on the left side of the Antarctic map, where Totten Glacier drains a portion of the East Antarctic ice sheet that is also increasingly losing mass. “Antarctica, the planet’s largest ice sheet, lost 219 billion tons of ice annually from 2012 through 2017 — approximately triple the 73 billion ton melt rate of a decade ago, the scientists concluded. From 1992 through 1997, Antarctica lost 49 billion tons of ice annually.” Thomas Frederikse Postdoctoral researcher, Jet Propulsion Laboratory/California Institute of Technology: This is a correct summary of the results from the study. Aimée Slangen Researcher, Royal Netherlands Institute for Sea Research (NIOZ): This translates to about 0.6 mm/yr in 2012-2017, while the 1992-1997 rates were 0.14 mm/yr. This may not sound like much, but the current total rate of sea-level rise is around 3.2 mm/yr, so Antarctica is responsible for an increasingly large portion of the observed sea-level rise. “The study is the product of a large group of Antarctic experts who collectively reviewed 24 recent measurements of Antarctic ice loss, reconciling their differences to produce the most definitive figures yet on changes in Antarctica.” Aimée Slangen Researcher, Royal Netherlands Institute for Sea Research (NIOZ): This sounds like there are only 24 data points, but the data going into the analysis is much more extensive than this, encompassing 24 types of measurements and analysis methodologies for the period from 1992 through to 2017. “Whether Antarctic mass loss keeps worsening depends on choices made today” Peter Neff Assistant Research Professor, University of Minnesota: This is the biggest opportunity to add more depth to the analysis of this new Antarctic ice loss result. An important point here is that the human fingerprint on this Antarctic mass loss is still hard to identify. A 2013 assessment1 showed that expert opinion is “uncertain and undecided” about whether recent ice sheet behavior simply reflects natural variability or is a response to human-caused climate change. This is essentially because our observations of ice sheet behavior are too short, 30 years at best for satellite observations of the ice sheet. This just meets the minimum definition of a “climatology” with respect to the atmosphere, and we know that the ice sheet operates on longer timescales than the atmosphere (it is a big system to move!). Although West Antarctica has been one of the fastest-warming places on the planet over the last 60 years (sparse weather records begin in 1957), as Steig et al showed in 20092 and Bromwich et al confirmed in 20133, how/whether this atmospheric warming has emerged from natural climate variability is less clear. It is also unclear how this warming trend will continue, as climate in West Antarctica is pushed around by Pacific Ocean-atmosphere variability. From ice core records we (myself and MANY others) have drilled and analyzed across this region we do not see recent anomalies exceeding variability over the last 2000 years4. From measurements of ice borehole temperatures in the same region, the ice itself directly records anomalous warmth over the last 50 years5. Antarctic weather is known to be harsh but it is also some of the most variable on the planet. The human fingerprint of atmospheric warming has emerged everywhere else on the planet as early as about 200 years ago, but we are still waiting for it to clearly emerge in Antarctica (see Figure 2 in Abram et al, 20166). As Mooney explains, how much atmospheric warming comes to Antarctica largely depends on our carbon emission choices in the near-term. In addition to all of this, the ice loss in West Antarctica is less driven by ocean warming as it is by increased delivery of relatively-warm deep ocean currents beneath ice shelves. This delivery is driven by the atmosphere; whether winds blow strong enough in the right direction to drive upwelling currents beneath Pacific-facing West Antarctic ice shelves. Decadal-scale variability of the Pacific Ocean-atmosphere system in turn affect the strength and position of these current-driving winds. Summary: it’s very complicated but the Pacific Ocean is the beast to watch for future West Antarctic ice loss, in combination with the dynamics of Pine Island, Thwaites, and a few smaller glaciers (Smith, Kohler) along the Amundsen Sea coast of West Antarctica. 1-Bamber and Aspinall (2013)An expert judgement assessment of future sea level rise from the ice sheets, Nature Climate Change 2-Steig et al (2019)Warming of the Antarctic ice-sheet surface since the 1957 International Geophysical Year, Nature 3-Bromwich et al (2013)Central West Antarctica among the most rapidly warming regions on Earth, Nature Geoscience 4-Steig et al (2013)Recent climate and ice-sheet changes in West Antarctica compared with the past 2,000 years, Nature Geoscience 5-Orsi et al (2012)Little Ice Age cold interval in West Antarctica: Evidence from borehole temperature at the West Antarctic Ice Sheet (WAIS) Divide, Geophysical Research Letters 6-Abram et al (2016)Early onset of industrial-era warming across the oceans and continents, Nature 2.Recent ice loss has primarily come from the West Antarctic Ice Sheet, making regional processes important to understanding the trend. “[The West Antarctic Ice Sheet] is known to be losing ice rapidly because it is being melted from below by warm ocean waters, a process that is rendering its largest glaciers unstable.” Peter Neff Assistant Research Professor, University of Minnesota: This is accurate but doesn’t fully explain that the warm ocean water is not a result of human-caused climate change and it is not a linear warming of Southern Ocean waters that causes melt beneath West Antarctic ice shelves. Rather, it is variability in the delivery of this relatively warm water (called Circumpolar Deep Water) that can directly affect how much melt is happening. Delivery of this water is altered by the direction and strength of winds over the Amundsen Sea, a subset of the Pacific sector of the Southern Ocean. If winds blow from west to east across the Amundsen Sea, they promote upwelling of this deep water under ice shelves, promoting melt and hence increasing ice loss*. Steig et al (2012)Tropical forcing of Circumpolar Deep Water Inflow and outlet glacier thinning in the Amundsen Sea Embayment, West Antarctica, Annals of Glaciology “The growth is largely attributable to just two huge glaciers — Pine Island and Thwaites. The latter is increasingly being viewed as posing a potential planetary emergency, because of its enormous size and its role as a gateway that could allow the ocean to someday access the entirety of West Antarctica, turning the marine-based ice sheet into a new sea.” Aimée Slangen Researcher, Royal Netherlands Institute for Sea Research (NIOZ): This is known as the Marine Ice Sheet Instability hypothesis (MISI), see Box 13.2 in the latest IPCC report(Working Group 1). Figure – Schematic of the processes leading to the potentially unstable retreat of a grounding line showing (a) geometry and ice fluxes of a marine icesheet, (b) the grounding line in steady state, (c) climate change triggering mass outflow from the ice sheet and the start of grounding line retreat and (d) self-sustainedretreat of the grounding line. Source: IPCC 3.The loss of Antarctic ice produces greater sea level in the Northern Hemisphere than it does near Antarctica. “‘That isn’t going to sound horribly unmanageable. But remember for the northern hemisphere, for North America, the fact that the location in West Antarctica is where the action is amplifies that rate of sea level rise by up to an about additional 25 percent in a city like Boston or New York.’ That’s because as Antarctica’s mass shrinks, the ice sheet’s gravitational pull on the ocean relaxes somewhat, and the seas travel back across the globe to pile up far away — with U.S. coasts being one prime destination.” Peter Neff Assistant Research Professor, University of Minnesota: What Rob DeConto and Chris Mooney explain here are the “far-field” sea level rise effects of losing so much concentrated ice mass in West Antarctica. This loss of mass reduces the gravitational pull that Antarctica otherwise has on the ocean, causing more water to slosh away from the far South. This just so happens to have a maximum impact on both coasts of North America, as illustrated in the Climate Science Special Report released in 2017 as part of the 4th National Climate Assessment undertaken by US federal agencies and universities. Figure 12.1 in the Sea Level Rise chapter shows that an extra 1.4 feet per century of relative sea level rise can be expected for North America (data originally from Kopp et al*), coming largely from the two largest West Antarctic glaciers—Pine Island and Thwaites Glaciers. Figure – Regional sea level rise patterns for ice loss from Greenland Ice Sheet (GIS), West Antarctica Ice Sheet (WAIS), East Antarctic Ice Sheet (EAIS), and movement of continental crust (GIA).(Source: US NCA) Kopp et al (2014)Probabilistic 21st and 22nd century sea‐level projections at a global network of tide‐gauge sites, Earth’s Future Aimée Slangen Researcher, Royal Netherlands Institute for Sea Research (NIOZ): This effect is called the gravitational effect, and it is the consequence of one of the basic laws of physics: mass attracts mass. When mass is lost on Antarctica, sea level will fall within a 2,200 km radius due to the loss of gravitational pull. Between 2,200 and 7,600 km, sea level will rise but less than the global average. Beyond 7,600 km, sea level rise will be larger than the global mean, up to 25% extra. For Antarctica, this means that the largest consequences will be in the Northern Hemisphere, with the reverse being true for mass loss in Greenland. The gravitational effect has been known since 18861, was rediscovered in 19762 and again in 20013. It is used in sea-level projections, for instance in the IPCC AR5 report, chapter 13. 1-Woodward (1886) On the form and position of the sea-level as dependent on superficial masses symmetrically disposed with respect to a radius of the Earth’s surface, Annals of Mathematics 2-Farrell and Clark (1976)On Postglacial Sea Level, Geophysical Journal International 3-Mitrovica et al (2001)Recent mass balance of polar ice sheets inferred from patterns of global sea-level change, Nature"
https://science.feedback.org/review/national-geographic-hurricanes-moving-slower-global-warming-craig-welch/,1.8,"National Geographic, by Craig Welch, on 2018-06-06.",,"""Hurricanes Are Moving Slower—And That's a Huge Problem""",,,,,"This National Geographic article covers a result reported in two recent studies: global warming seems to be causing the movement rate of hurricanes to slow. One study shows this trend in data going back to about 1950, while the other simulates hurricanes in an even warmer world using a climate model. While the process responsible for this trend needs to be studied further, it could be due to a general slowing of winds in areas where hurricanes exist due to differences in warming rate between low and high latitudes. Scientists who reviewed the article concluded that it does a good job of placing the finding in context and asking input from scientists with expertise on the topic for validation.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Dan Chavas Assistant Professor, Purdue University: This is an important topic and the article explains the new research findings clearly and in terms that can be understood by laypeople. Highlighting how this result about slowing storms is consistent across two studies that employ very different methodologies further helps convey to the public how we try to use multiple lines of evidence to understand how our world works and how it may chance in the future. Kerry Emanuel Professor of Atmospheric Science, MIT: The story accurately conveys the essence of the original paper by James Kossin. Emmanuel Vincent Founder & Executive Director, Science Feedback: The National Geographic article covers two new scientific studies that provide evidence that ongoing global warming is decreasing the translation speed of hurricanes. One study shows a 10% reduction in observed translation speed between 1949 and 2016 while the second finds a ~10% reduction in translation speed of two dozen hurricanes simulated in a warmer future by the end of the 21st century. The fact that two independent studies using different approaches corroborate the finding increases the confidence one can have in this surprising result, even though it remains to be validated further. The article correctly emphasizes a more strongly established scientific result: that hurricanes drive significantly more rainfall in a warmer climate, which is a major aspect of their destructiveness. Karthik Balaguru Scientist, Pacific Northwest National Laboratory: The findings from the study are consistent with the idea of a slowdown of the Hadley circulation in response to global warming. However, it’ll be interesting to see if similar trends are obtained when using hurricane track data over the satellite period, when the data is more accurate. One of the main points of the article is that the slowdown of hurricanes is occurring over land, which can certainly have serious implications. But over the ocean, which has roughly 90% of the data, the impacts of a slowdown are not entirely clear to me. For instance, it is known that slower hurricanes create a stronger cold wake and hence become more susceptible to ocean feedback. How this may influence the intensity of the storms needs careful evaluation. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Annotations: The statements quoted below are from the article; comments and replies are from the reviewers. “Hurricanes Are Moving Slower—And That’s a Huge Problem” Kerry Emanuel Professor of Atmospheric Science, MIT: “Huge” may be an exaggeration. “While having a cyclone travel with less speed may seem like a good thing, it’s actually just the opposite. Wind speeds within the storm remain high, but the whole system itself moves slower across the landscape, allowing punishing rains to linger longer over communities.” Emmanuel Vincent Founder & Executive Director, Science Feedback: Another consequence could be to weaken storms while they move over the ocean since slower storms cause greater ocean cooling* and colder surface water decrease hurricanes strength. That would be an interesting hypothesis to test. Vincent et al (2012) Assessing the Oceanic Control on the Amplitude of Sea Surface Cooling induced by Tropical Cyclones,Journal of Geophysical Research"
https://science.feedback.org/review/new-york-times-story-accurately-describes-rio-grandes-climate-context-henry-fountain/,1,"The New York Times, by Henry Fountain, on 2018-05-24.",,"""In a Warming West, the Rio Grande Is Drying Up""",,,,,"This article in The New York Times discusses water supply issues along the Rio Grande in New Mexico, and the projected impacts of climate change. Scientists who reviewed the article generally found it to be an accurate description of research on this topic. However, they note that it’s important to remember that precipitation in this region can naturally vary on timescales longer than just one year to the next. Even changes from one decade to the next should be considered carefully in the context of variability—and water supply risks depend on both human-caused trends and that natural variability.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Ted Letcher Research Scientist, Cold Regions Research and Engineering Lab: I couldn’t find any serious flaws in the scientific information provided in this article, at least from an atmospheric / climate perspective. The issue of water resource management in the western US and how it fits within a changing climate is extremely complex and spans many disciplines from climatology to hydrology to city planning to population dynamics, and so on. This article does a nice job presenting the very basics of the climate science involved and tying the greater changes to the personal stories of people in the region. My only complaints are that the article uses a 14 year trend to discuss broader climate concerns without addressing low-frequency climate variability, and it misses out on an opportunity to discuss how regional climate feedback mechanisms play a role. Naama Raz Yaseef Project Scientist, Lawrence Berkeley National Laboratory: I did not find any inaccuracies and most important aspects were included. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Annotations: The statements quoted below are from the article; comments and replies are from the reviewers. The monsoon rains he is counting on are notoriously unpredictable, however. Yes, the main rain season is in the summer (July – August) but the main source for the rivers’ flow is the melting of the snowpack, which has been decreasing over time. The Rio Grande is a classic “feast or famine” river, with a dry year or two typically followed by a couple of wet years that allow for recovery. Weird wording. It’s just an arid river with high inter-annual variability in precipitation and flows. If warming temperatures brought on by greenhouse gas emissions make wet years less wet and dry years even drier, as scientists anticipate, year-to-year recovery will become more difficult. This is true, but it is a BIG IF. Climate warming is expected to create intensification of the hydrologic cycle here as well, meaning that heaviest annual rainfall events may become more intense. So, overall—less rain, but the large storms will be even larger and create flash floods. The effect of long-term warming is to make it harder to count on snowmelt runoff in wet times This is true even if there is no large-scale change in overall precipitation in the watershed. Warmer temperatures will both increase local evaporation rates and cause an earlier and reduced snowmelt season. Both of these mechanisms reduce the availability of snowmelt runoff through the summer. A study last year of the Colorado River, which provides water to 40 million people and is far bigger than the Rio Grande, found that flows from 2000 to 2014 were nearly 20 percent below the 20th century average, with about a third of the reduction attributable to human-caused warming. The study suggested that if climate change continued unabated, human-induced warming could eventually reduce Colorado flows by at least an additional one-third this century. While this statement is largely true, it is important to note that 14 years is a relatively short time period, climatologically speaking. Moreover, this paragraph largely glosses over the key finding of this study, which is that temperature increases ALONE (i.e., in absence of changes in precipitation) are likely to cause a runoff reduction of about 6-7% per degree Celsius of warming. This means that there is increased certainty that the southwest US will experience more severe droughts in the future, even if there is heightened uncertainty in climate model regional precipitation projections. Last year, though, was a wet one on the Rio Grande, with a strong snowpack in the winter of 2016-17 that allowed the conservancy district to store water in upstream reservoirs. Wet years may actually be “wetter” than today due to the fact that a warmer atmosphere can hold more water. (For example, see Rasmussen et al, 2011*.) So, it’s likely that we’ll see occasional news reports concerning record snowfalls, or record annual snow accumulations in the Rocky Mountains, even as the region dries out and becomes increasingly prone to extended droughts. Rasmussen et al (2011)High-Resolution Coupled Climate Runoff Simulations of Seasonal Snowfall over Colorado: A Process Study of Current and Warmer Climate, Journal of Climate Temperatures in the Southwest increased by nearly two degrees Fahrenheit (one degree Celsius) from 1901 to 2010, and some climate models forecast a total rise of six degrees or more by the end of this century. I checked various sources and these numbers are about right, an increase of almost 2 °F, or +0.17/decade1. Annual temperatures in New Mexico are projected to rise another 3.5 to 8.5°F by 21002. 1-Tebaldi et al (2012) The heat is on: U.S. temperature trends, Climate Central 2-NOAA Technical Report NESDIS 142-5 (2013) Regional Climate Trends and Scenarios for the U.S. National Climate Assessment. Part 5. Climate of the Southwest U.S. True, but in the spirit of transparency, some models forecast only 1.5 -3 degrees of warming. Dr. Gutzler said spring temperatures have an impact, too, with warmer air causing more snow to turn to vapor and essentially disappear. A longer and warmer growing season also has an effect, Dr. Overpeck said, as plants take up more water, further reducing stream flows. And increased soil evaporation."
https://science.feedback.org/review/wall-street-journal-commentary-grossly-misleads-readers-about-science-of-sea-level-rise-fred-singer/,-1.8,"The Wall Street Journal, by Fred Singer, on 2018-05-15.",,"""The Sea Is Rising, but Not Because of Climate Change""",,,,,"This commentary published by The Wall Street Journal, written by Fred Singer, claims that warming (and therefore greenhouse gas emissions) has no effect on global sea level rise. Although Singer concedes the physical fact that water expands as its temperature increases, he claims that this process must be offset by growth of Antarctic ice sheets. Scientists who reviewed this opinion piece explained that it is contradicted by a wealth of data and research. Singer bases his conclusion entirely on a cherry-picked comparison of sea level rise 1915-1945 and a single study published in 1990, claiming a lack of accelerating sea level rise despite continued warming. But in fact, modern research utilizing all available data clearly indicates that sea level rise has accelerated, and is unambiguously the result of human-caused global warming. Since the 1990s for example, satellites have measured an acceleration in the rate of global sea level rise: Figure – Global mean sea level (blue), after removing an estimate for the impacts of the eruption of Mount Pinatubo (red), and after also removing the influence of El Niño (green), fit with a quadratic (black).FromNerem et al. (2018)See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Chris Roberts Research Scientist, ECMWF/Met Office: This article severely misrepresents the scientific understanding of the processes responsible for observed changes in global sea level. Understanding and attributing the causes of changes in global sea level is an area of active research and there are genuine uncertainties, but there is a clear consensus on the important roles for ocean thermal expansion and addition of mass to the oceans from melting glaciers and ice caps during recent decades. For example, the following paper by Church et al. (2008)* summarizes the independent lines of evidence for changes in sea level from satellite altimeter and tide gauge measurements and how these changes can be explained by a combination of thermal expansion and exchange of mass (either liquid water or ice) between the oceans and continents: Figure – Global sea‐level budget from 1961 to 2008. (left) The observed sea level using coastal and island tide gauges (solid black line with grey shading indicating the estimated uncertainty) and using satellite altimeter data (dashed black line) with thermal expansion and glaciers melting components; terrestrial storage (e.g. dams) partially offsets other contributions to sea‐level rise. (right) The observed sea level and the sum of components. Church et al (2011)Revisiting the Earth’s sea‐level and energy budgets from 1961 to 2008, Geophysical Research Letters Stefan Rahmstorf Professor, Potsdam University: The article has almost nothing to do with the modern state of sea-level science. The author tries to call into question that global warming causes sea-level rise, and does so by cherry-picking a short segment of data from 1915-1945, a time when data quality is poor and the warming signal small—a bizarre approach that could never pass scientific peer review and is apparently aimed at misleading a lay audience. Keven Roy Research Fellow, Nanyang Technological University: This article is misleading, and presents inaccurate statements about global mean sea level rise. Benjamin Horton Professor, Earth Observatory of Singapore: If this were an essay in one of my undergraduate classes, he would fail. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from Fred Singer; comments and replies are from the reviewers. 1. Fred Singer’s opinion relies on outdated, cherry-picked data. The noted oceanographer Walter Munk referred to sea-level rise as an “enigma” Benjamin Horton Professor, Earth Observatory of Singapore: It is interesting that this opinion piece starts off with “Munk’s enigma”. This was introduced by famed oceanographer Walter Munk in a 2002 paper published in Proceedings of the National Academy of Sciences. The enigma refers to a key discrepancy between the amount of sea-level rise believed to have occurred during the 20th century and the effects it should have produced on the planet — specifically, on the Earth’s rotation. So in addition to all the devastating and obvious effects sea-level rise will produce on the planet, such as flooding and erosion, sea-level rise also has the more subtle, but nonetheless mind-boggling ability to alter the way the Earth rotates on its axis. In a recent paper, Jerry Mitrovica and an interdisciplinary team of colleagues claim to have resolved the enigma. They reinforce the awe-inspiring power of climate change to produce global-scale effects, changing the planet’s very rotation. I don’t understand the relevance of citing Walter Munk to support Singer’s argument. I chose to assess the sea-level trend from 1915-45 Benjamin Horton Professor, Earth Observatory of Singapore: This is a blatant case of cherry picking to confirm a Singer’s position while ignoring all other instrumental sea level data that may contradict that position. This fallacy is a major problem in public debate. Stefan Rahmstorf Professor, Potsdam University: It is rather ironic that the author first complains about “poor data” and then goes on to cherry-pick a time of particularly poor data that includes the World War 2 period. Even the temperature data from this period are questionable; the sea surface temperature data show a strong warm peak at the end of WW2 (the basis of his claim of 0.5 °C warming) which is probably a data collection artefact, given that no such warming is seen in the data collected at the global network of weather stations on land. Also, in the peer-reviewed literature it has been shown that minor inaccuracies in sea-level data by just a few millimeters can lead to spurious fluctuations of sea level trends when too-short time intervals are considered*. Rahmstorf et al (2011)Testing the robustness of semi-empirical sea level projections, Climate Dynamics I note particularly that sea-level rise is not affected by the warming; it continues at the same rate, 1.8 millimeters a year, according to a 1990 review by Andrew S. Trupin and John Wahr. Stefan Rahmstorf Professor, Potsdam University: This claim is against the basic laws of physics—warming causes thermal expansion of sea water and thereby sea-level rise, full stop. This is true regardless of whether this effect can be detected in a cherry-picked short time interval with poor data quality. Keven Roy Research Fellow, Nanyang Technological University: This is very misleading. Why is the author using a review dating from 1990, when there have been many publications over the past 28 years that show a much higher rate of Global Mean Sea Level (GMSL) rise over the last few decades? For instance, Hay et al* have looked at tide gauge records since the beginning of the 20th century and found that the rate of GMSL rise was 1.2 +/- 0.2 mm/yr over the 1901-1990 period, but 3.0 +/- 0.7 mm/yr over the 1993-2010 period (this period corresponds to the time for which we also have satellite altimetry measurements, which are consistent with this rate). The author also talks about an “accelerating rate” of sea-level rise later in his article, which contradicts his own statement. Hay et al (2015) Probabilistic reanalysis of twentieth-century sea-level rise, Nature The trend has been measured by a network of tidal gauges, many of which have been collecting data for over a century. Ernst Schrama Associate Professor, Delft University of Technology: There are more indicators than a network of tide gauges. The mass loss of West Antarctica and Greenland is observed by satellite gravimetry, and it shows an acceleration in the mass loss*. Seo et al (2015) Surface mass balance contributions to acceleration of Antarctic ice mass loss during 2003–2013,Journal of Geophysical Research: Solid Earth Velicogna et al (2014)Regional acceleration in ice mass loss from Greenland and Antarctica using GRACE time‐variable gravity data,Geophysical Research Letters [read “New York Times series accurately describes research on Antarctic ice sheets and sea level rise, but highlights uncertain studies” for further details] 2. Global sea level is rising mainly due to melting glacial ice and warming oceans. Locally, coastal sea level changes are also influenced by vertical land motion. But efforts to determine what causes seas to rise are marred by poor data and disagreements about methodology.Stefan Rahmstorf Professor, Potsdam University: This is not correct. First of all, the oceans are warming and warming water expands—a basic law of physics. Second, mountain glaciers and ice sheets are melting due to global warming, adding water to the ocean—an observational fact. Third, independent estimates of these contributions to sea-level rise match the actually observed sea level rise. Ernst Schrama Associate Professor, Delft University of Technology: I think this is a misinterpretation of what is currently known about sea level rise where we know that roughly 50% comes from glaciers’ mass loss, and the other 50% comes from volume expansion because of heat. There are multiple independent observation systems that confirm the current knowledge. as continents rise after the overlying ice has melted Keven Roy Research Fellow, Nanyang Technological University: Glacial Isostatic Adjustment (GIA) also causes subsidence of the solid Earth surface in the regions located outside the margins of the former ice sheets (for instance, along the U.S. East coast, where GIA-related subsidence is exacerbating the effects of global mean sea level rise). contrary to the general wisdom—that the temperature of sea water has no direct effect on sea-level rise Stefan Rahmstorf Professor, Potsdam University: This is not just against conventional wisdom but also against the laws of physics. I conclude that it must be ice accumulation, through evaporation of ocean water, and subsequent precipitation turning into ice. Evidence suggests that accumulation of ice on the Antarctic continent has been offsetting the steric effect for at least several centuries. Ernst Schrama Associate Professor, Delft University of Technology: There is only one place on East Antarctica, called Dronning Maud land, where there is some growth of the Antarctica Ice Sheet, and it does not compensate for the loss that we observe with satellite gravimetry on other parts of Antarctica. Stefan Rahmstorf Professor, Potsdam University: Satellite data show that mountain glaciers as well as the large ice sheets on Greenland and Antarctica are all losing ice mass in recent decades, at an accelerating rate. Check out NASA’s data: Figure – GRACE Satellite measurements of ice mass variations in Antarctica and Greenland since 2003. It is difficult to explain why evaporation of seawater produces approximately 100% cancellation of expansion.Stefan Rahmstorf Professor, Potsdam University: It would indeed be difficult to explain. But it just doesn’t, otherwise sea level would not be rising. Currently, sea-level rise does not seem to depend on ocean temperature, and certainly not on CO2.Stefan Rahmstorf Professor, Potsdam University: There is a clear relationship between the accelerating rate of sea-level rise and the increasing global temperature, which is shown in this post (e.g. in Figure 3). 3. Sea level rise is currently accelerating as a result of human-caused global warming. But there is also good data showing sea levels are in fact rising at an accelerating rate. Stefan Rahmstorf Professor, Potsdam University: Indeed. 1 to 2 millimeters a year Keven Roy Research Fellow, Nanyang Technological University: This is not the current rate of observed global mean sea level rise. It is rather around 3.0 mm/yr*. Dieng et al (2017)New estimate of the current rate of sea level rise from a sea level budget approach, Geophysical Research Letters All this, because it is much warmer now than 12,000 years ago, at the end of the most recent glaciation. Stefan Rahmstorf Professor, Potsdam University: Data from sediment cores from around the world show that none of the preceding 20 Centuries show even remotely as much sea-level rise as the 20th Century. Think about it: over the past decades, sea levels have been rising at a rate of 3 cm per decade, as satellites show. If this had been going on for millennia, then just 1,000 years ago, in the Middle Ages, sea levels would have been 3 meters lower than today, and in Roman times 6 meters. That is definitely not the case as many remaining coastal structures from earlier times show (e.g. Roman fish ponds that were connected to the sea). The entire article is nonsensical. By 2100 the seas will rise another 6 inches or so—a far cry from Al Gore’s alarming numbers Benjamin Horton Professor, Earth Observatory of Singapore: They are not Al Gore’s numbers! These are the sea-level rise projections from the scientific community who go through the peer review process. That is, the evaluation of the sea-level projections by one or more people of similar competence to the producers of the work (peers). It constitutes a form of self-regulation by qualified members of a profession within the relevant field. Peer review methods are employed to maintain standards of quality, improve performance, and provide credibility of sea level projections. [read “Sea level could rise by as much as 1 or 2 meters (3.3-6.6 feet) by the year 2100” for further details] Mr. Singer is a professor emeritus of environmental science at the University of Virginia. He founded the Science and Environmental Policy Project and the Nongovernmental International Panel on Climate Change. Ernst Schrama Associate Professor, Delft University of Technology: Fred Singer has a long history or raising false and misleading arguments that deny climate change. It is difficult to understand that the Wall Street Journal provides him a platform to display his statements. Please read the last assessment report of the IPCC, it provides a good description of the scientific knowledge with regard to sea level change and the relation to climate change."
https://science.feedback.org/review/business-insider-highlights-health-impacts-climate-change-aspects-are-misleading-kevin-loria/,-0.2,"Business Insider, by Kevin Loria, on 2018-05-08.",,"""The amount of carbon dioxide in the atmosphere just hit its highest level in 800,000 years and scientists predict deadly consequences""",,,,,"This article at Business Insider describes the impacts of climate change on human health which covering the fact that the concentration of CO2 in the atmosphere recently passed 410 parts per million. Scientists who reviewed the article found that many of the listed impacts were described accurately and supported with links to relevant published studies. However, cited numbers for current deaths due to common air pollutants and the concentration at which CO2 itself can impact brain function are misleading. In their comments, the scientists provide context for interpreting these numbers.Additionally, the article’s language conflates CO2’s effect as a climate-changing gas with the direct health effects of other pollutants.See all the scientists’ annotations in contextGUEST COMMENTS: Philip Staddon Lecturer/Visiting Scholar, The Open University, Xi’an Jiaotong-Liverpool University: The article’s title point that CO2 levels are now the highest in 800,000 years is correct. The health cost and deaths caused by climate change are underestimated. We are talking millions here, mostly in the poorer countries, linked to food and water security and to spread of infectious vector borne diseases (Dengue, Malaria). There’s confusion with air pollution–a common confusion. However, air pollution is an additional burden caused by particulates, surface O3, and NOx, etc. in the air, which will be exacerbated by climate change causing untold misery to hundreds of millions of people. Michael Brauer Professor, The University of British Columbia: Instead of improving clarity regarding climate change/warming/CO2 emissions and impacts, this article increases confusion by mixing direct impacts of CO2 and warming with indirect impacts related to warming and impacts (e.g air pollution) arising from some of the same sources as those responsible for much of the CO2 emissions. The article focuses on CO2 levels and suggests that CO2 itself (as opposed to climate change) is directly responsible for much of the impacts arising from these emissions—this is misleading and the article barely mentions the impact of CO2 on climate.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Kristie Ebi Professor, University of Washington: While it is positive that the author discussed the adverse health consequences of climate change, it appears the author selected studies projecting particularly high consequences. Other studies of how climate change could affect the same health outcomes project fewer injuries, illnesses, and deaths than those cited in the article, and project much lower risks when including adaptation and mitigation. The statement that 9 million people died prematurely from pollution-related diseases refers to more than just air pollution; the paper stated that in 2015, 4.2 million died prematurely from ambient particle pollution and 0.3 million from ambient ozone pollution*. The cited study on cognition reported that ambient carbon dioxide can affect human decision-making performance at concentrations of 1,000 ppm and 2,500 ppm, from a baseline of 600 ppm. Assuming a rate of increase of carbon dioxide equivalent to the last five years (10 ppm in 5 years), it would be another 300 years before ambient concentrations exceed 1,000 ppm. Landrigan et al (2017)The Lancet Commission on pollution and health, The Lancet Jason West Associate Professor, University of North Carolina at Chapel Hill: The article draws attention to the high CO2 at present and the health risks of climate change, but it gives the incorrect impression that breathing CO2 directly is a major cause of concern. The most important health effects of climate change—heat stress, vector-borne diseases, air pollution, access to food and water, severe storms, displacement—do get some discussion here. Markus Donat Research Fellow, University of New South Wales: To me, “CO2 levels could lead to tens of thousands of pollution-related deaths” sounds quite misleading because it seems to say people may die as a direct consequence of CO2 pollution (i.e., being poisoned?), but this is certainly not the case at the 550 ppm concentration mentioned later. No doubt that increasing CO2 leads to warming—and this will cause rising sea levels and more intense and more frequent heat waves. “Superstorms” is less clear as to what the author means; there are no clear conclusions about the intensity of storm systems, but it is plausible and likely that the precipitation related to intense storms will increase due to the higher water holding capacity of warmer air. Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: I think in general this article is pretty good—there are many links to peer-reviewed scientific studies in there, and in general the authors have done their homework. The writing suggests the author has a sufficiently clear understanding of the science, and doesn’t over extrapolate from the data. However, I think there are a few lapses in the article that display a tendency to over-hype. For instance, one of the few times where the author doesn’t provide a reference is when they suggest a very high climate sensitivity to CO2 rise—+6˚C when we get to 550 ppm. I think this figure was taken from one of the other articles linked in this article, but in turn that article provides no reference for this claim. It’s a very high estimate compared to most models, and might betray a tendency of the author to emphasise the catastrophic. However, there are a lot of legitimate points in there, and since this lapse doesn’t constitute a central part to the story, I think it would be unfair to describe the whole article as of low credibility. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Annotations: The statements quoted below are from the article; comments and replies are from the reviewers. Research indicates that if unchecked, increased CO2 levels could[…] reach a point at which it slows human cognition Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: This is perhaps over-stated here. The study that the writer is citing studied behaviour in an office environment at 600, 1000, and 2,500 ppm. The prospect of 2,500 ppm CO2 in the atmosphere is, I would hope, quite some way off (it is beyond the vast majority of projections for 2100 for example).. so this seems a little excessive here. If CO2 gets to 2,500ppm, I’m pretty certain it’s not going to be the reduced performance in decision-making performance that kills us! There’s a debate among scientists about the last time CO2 levels were this high. Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: It’s probably fair to say that there remain a few disagreements, but the community is largely moving toward acceptance that the Pliocene was likely around this high (see e.g. www.p-co2.org). Nothing really strictly wrong with this passage, although I think most would agree the Pliocene is more likely than the Miocene. Some experts think we’re on track to hit 550 ppm by the end of the century, which would cause average global temperatures to rise by 6 degrees Celsius Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: This assumes a very high climate sensitivity compared to most IPCC-class models. Can the authors give a source for where they got this estimate? It appears to be a quote from the previous link, which itself has no reference either. Most estimates tend to fall around 3 ˚C/doubling, and 550 is ~1 doubling of CO2 vs. pre-industrial of 280 ppm. So that would suggest ~3˚C total, of which maybe 1 ˚C has already happened. Maybe one saving grace here is that 550 ppm is perhaps one of the more conservative estimates for the end of the century."
https://science.feedback.org/review/the-australian-coverage-great-barrier-reef-perception-scientists-divided-global-warming-graham-lloyd/,-1.3,"The Australian, by Graham Lloyd, on 2018-04-19.",,"""Not all scientists agree on cause of Great Barrier Reef damage""",,,,,"This article in The Australian covers a new study published in Nature that concludes global warming played a key role in the recent large-scale bleaching and mortality of corals in the Great Barrier Reef. Based on the comments of a single oceanographer (Prof. Kaempf), the article was headlined “Not all scientists agree on cause of Great Barrier Reef damage”. The scientists who reviewed this article found that this source’s comments in the story are unsupported by evidence and prior research, and therefore The Australian article misleads readers by emphasizing a “debate” that does not actually exist among researchers studying the Great Barrier Reef.See all the scientists’ annotations in context If this link does not work, addHypothesisto your browser and switch it on when thearticle pagehas loaded.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Andrew King Research fellow, University of Melbourne: The Australian chooses to present a mixed message on this story when the science is extremely clear. The title and quote from Prof. Kaempf do not represent the views of the broader scientific community. John Bruno Professor, The University of North Carolina at Chapel Hill: An otherwise fair and accurate article, except for the misleading headline and nonsense opinion from Dr. Kaempf. Dr. Kaempf is obviously not familiar with the relevant science. While the bleaching did occur during the peak of an El Niño event (the high point of a natural cycle), the anomalously high temperatures were (with high certainty) caused by ocean warming. Natural El Niño events affect the GBR once or twice a decade and have for thousands of years. Yet until recently they had only minor, if any impacts. It is the background warming of the seas, caused by greenhouse gas emissions, that is increasing the peaks of the ENSO cycle, making “heat waves” more severe. This natural cycle is essentially riding on the back of gradual increases in temperature over the last century. The scientific basis for this is widely understood and accepted by the scientific community, including the vast majority of physical oceanographers. While it is evidently true (if surprising) that not every single scientist agrees with this explanation, a vast majority do. Terry Hughes Professor, ARC Centre of Excellence for Coral Reef Studies, James Cook University: [Prof. Hughes was lead author of the Nature study.] The article quotes a scientist who has no expertise in climate change, ecology, or coral reefs, who claims that the global record-breaking temperatures in 2016 were not due to climate change. Fifty percent of corals on the Great Barrier Reef died on the Great Barrier Reef in 2016-2017, and the article seeks to downplay this unprecedented loss. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Annotations: The statements quoted below are from the article; comments and replies are from the reviewers. “the claimed link between the 2016 heatwave and global warming has no scientific basis” Sarah Perkins-Kirkpatrick Research Scientist, Climate Change Research Centre, The University of New South Wales: Wrong. Check this article. That analysis was based on peer-reviewed methods. The El Niño Southern Oscillation did have some influence on the bleaching, but it was much less than in previous bleaching events. “an individual heatwave triggering coral bleaching cannot be linked to global warming as the process triggering an individual heatwave is fundamentally different from that triggering global warming” Sarah Perkins-Kirkpatrick Research Scientist, Climate Change Research Centre, The University of New South Wales: There is a recent paper showing how marine heatwaves have increased over the last 90-100 years globally*. There are physical processes aside from climate change that cause marine heatwaves, but the rise in global temperatures are causing marine heatwaves to be less transient—more are occurring because of climate change and not from original physical processes. Oliver et al (2018) Longer and more frequent marine heatwaves over the past century, Nature Communications Andrew King Research fellow, University of Melbourne: Unfortunately, even under the Paris Agreement, 2016-like heat will be more common*. King et al (2017)Australian climate extremes at 1.5 °C and 2 °C of global warming, Nature Climate Change"
https://science.feedback.org/review/investors-business-daily-editorial-misrepresents-study-to-claim-plants-will-prevent-dangerous-climate-change/,-2,"Investors' Business Daily, by Anonymous, on 2018-04-09.",,"""A Startling New Discovery Could Destroy All Those Global Warming Doomsday Forecasts""",,,,,"This editorial by Investor’s Business Daily centers on a recent study published in Science, which concerns the sources of nitrogen cycling through Earth’s ecosystems. The editorial then claims that this study shows that plants will be able to soak up future human-caused emissions of carbon dioxide because nitrogen is plentiful, proving projections of rapid global warming wrong. The first author of the new Science study, and other scientists who reviewed the editorial, explained that this is incorrect and poorly reasoned. If the editorial’s claims about nitrogen availability for plants were true, past CO2 emissions would also have had little effect on the concentration in the atmosphere. We know this is false—the concentration of CO2 in the atmosphere has been steadily increasing since daily measurements began in 1958, and the Earth has warmed as a result.See all the scientists’ annotations in contextGUEST COMMENTS: Benjamin Houlton, Professor, University of California, Davis (first author of the Science study): Our nitrogen study does not detract from the urgency of the climate problem, nor the unequivocal evidence of the role of carbon pollution in causing global climate change. The climate threat is clear and present and we must solve it rapidly by reducing emissions and capturing existing CO2 from the atmosphere. Rock nitrogen, if shown to be a significant part of the terrestrial cycle in future research, will continue to contribute to carbon storage in vegetation and soil. But the amount of rock nitrogen available is not enough to counterbalance the need to aggressively reduce carbon emissions worldwide. Our study does not suggest or imply that rock nitrogen will solve global climate change. Rather, we must invest in a clean energy economy and create negative carbon capture technologies at scale to reduce the risks of climate change on people, infrastructure, natural habitats, and the economy.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Charles Koven Staff Scientist, Lawrence Berkeley National Lab: This editorial totally misrepresents many things: the way nitrogen limitations are currently accounted for in global warming projections, the importance of the newly published work in governing carbon uptake by plants, and the way in which scientists construct models and incorporate new results. Sara Vicca Postdoctoral research fellow, University of Antwerp: The article includes several false statements and flawed reasonings, and suggests without evidencethat scientists refuse to see when their model assumptions and projections are wrong. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Annotations: The statements quoted below are from the article; comments and replies are from the reviewers. “Scientists just discovered a massive, heretofore unknown, source of nitrogen” Peter Thorne Professor, Maynooth University: That the rocks in the crust of the planet contain nitrogen has been known for in excess of a century. “If Houlton’s finding about these vast, previously unknown nitrogen stores holds true, then it would have an enormous impact on global warming predictions.” Peter Thorne Professor, Maynooth University: Misleading inference. Nitrogen availability is just one factor in net primary productivity (carbon sequestration over land). Other factors include but are not limited to seasonal temperatures and precipitation patterns and availability of other nutrients. In some areas nitrogen may well be limiting but to imply it is the limiting factor is without basis.Sara Vicca Postdoctoral research fellow, University of Antwerp: This source has always existed, and still many ecosystems are nitrogen limited. This demonstrates that nitrogen from rocks cannot resolve nitrogen limitation. Charles Koven Staff Scientist, Lawrence Berkeley National Lab: This is wrong. The majority of Earth system models used for global warming projections in the most recent IPCC assessment didn’t include any nitrogen constraints at all. What this means is that they assumed plants would be able to take up excess CO2 without this nutrient limitation—so its a case where almost all the models have a known limitation that will bias their results towards assuming less global warming than they should. So the Houlton paper, if correct, suggesting that the limitation by nitrogen is weaker than some previous estimates, would still imply a stronger constraint than the Earth system models that don’t include nitrogen at all. “But climate scientists assumed that the ability to plants to perform this function was limited because the availability of nitrogen in the atmosphere was limited.” Peter Thorne Professor, Maynooth University: Given that nitrogen by volume constitutes 78% of the Earth’s atmosphere it could hardly be described as limited. Climate scientists know that the ability is limited because we can, within uncertainties, close the carbon budget. This closure shows that roughly for every three carbon dioxide molecules emitted by fossil fuel combustion one is ending up in the ocean, one in the terrestrial biosphere, and one remains in the atmosphere. This is an observed and verified behaviour. Plants are removing approximately 1/3 of the excess carbon added by humans and this has remained broadly stable over several decades. “‘there will not be enough nitrogen available to sustain the high carbon uptake scenarios.’” Peter Thorne Professor, Maynooth University: This is around whether there may be a reduction in the ability in future of the terrestrial biosphere to uptake carbon. If nitrogen is the sole limitation then indeed the risk is a reduction in ability of the biosphere to uptake carbon. But, it is over-simplistic to consider nitrogen uptake the sole potential limiting factor as implied by this quotation. “Houlton has been exploring this possibility for years. Back in 2011, he reported that forest trees can tap into nitrogen found in rock. At the time, he said ‘the stunning finding that forests can also feed on nitrogen in rocks has the potential to change all projections related to climate change,’ because it meant there could be more carbon storage on land and less in the atmosphere than climate models say.” Peter Thorne Professor, Maynooth University: It should be noted that much of the Net Primary Productivity arises from grasses and other non-boreal sources. If only trees that are deep rooted enough to reach bedrock can tap this source then the potential is very much geographically limited. “They failed to predict a decadelong [sic] pause in global temperatures.” Peter Thorne Professor, Maynooth University: Individual runs of individual models did capture such behaviour as has been shown by a wealth of literature on the topic. On a decadal scale, natural variability plays an important role, as can short-lived forcing effects. The scientific community has a substantial understanding of the “pause” and its causes. This understanding builds rather than diminishes confidence in the climate models. “Nor have various calamities that were supposed to have occurred by now materialized.” Kerry Emanuel Professor of Atmospheric Science, MIT: We predicted, 31 years ago, that hurricane intensity would increase with greenhouse gas concentrations. In 2013, Typhoon Haiyan set the world record wind speed in a landfalling tropical cyclone, and in 2015 eastern North Pacific Hurricane Patricia set an all time record for hurricane winds. Hurricane Irma of 2017 maintained category 5 status for longer than any storm on record. Do tell the residents of Tacloban, Puerto Rico, and the Virgin Islands that they have not experienced calamities. “Meanwhile, the National Oceanic and Atmospheric Administration has been conducting highly suspicious temperature data manipulation. The changes in the temperature data consistently make the past seem cooler, which in turn makes the present seem warmer.” Peter Thorne Professor, Maynooth University: The NOAA temperature analyses have been thoroughly documented in the peer-reviewed literature, independently evaluated, and are comparable to several completely independently produced estimates. The largest adjustment serves to remove an artificial warming in the ocean temperatures in the mid-20th Century. This adjustment dwarfs all others applied. Unadjusted data show more warming since the late 19th Century than the adjusted records from NOAA and elsewhere do."
https://science.feedback.org/review/rush-limbaugh-falsely-claims-there-is-no-evidence-of-human-caused-global-warming/,Inaccurate,"The Rush Limbaugh Show, Rush Limbaugh, 2018-04-02",There isn’t yet any empirical evidence for their claim that greenhouse gases even cause temperatures to increase.,,"Factually Inaccurate: It is an unequivocal fact that Earth’s climate has warmed over the past century. Also, the conclusion that the human-caused increase of greenhouse gases is causing warming is supported by a wide range of empirical data.","Human-caused global warming is not a theoretical, future prediction—it has already occurred. Warming of the atmosphere and oceans is extensively documented, and the role of increased greenhouse gases in this warming has been determined from multiple lines of evidence.","There isn’t any warming. All they’ve got is computer model predictions, folks. There isn’t yet any empirical evidence for their claim that greenhouse gases even cause temperatures to increase. There isn’t any empirical data for that.",,"Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: This claim is not accurate. Global temperature datasets, developed by a number of independent research groups, show robust warming in the troposphere and at the Earth’s surface. The radiative effect of carbon dioxide has also been observed1. Considering multiple lines of evidence, the IPCC concluded that it is “extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century.” More recent analysis of satellite data shows that tropospheric warming from the satellite record is pronounced and cannot be explained by natural climate variability alone2. 1-Feldman et al (2015)Observational determination of surface radiative forcing by CO2 from 2000 to 2010, Nature 2-Santer et al (2017)Tropospheric Warming Over The Past Two Decades, Scientific Reports Mark Richardson Research Associate, Colorado State University/NASA JPL: Rush Limbaugh’s comments would have been fair in 1896 when Svante Arrhenius calculated that we could cause serious global warming1. But the past century of measurements mean that around 97% of specialists now agree that humans are the main cause of global warming2,3, and Limbaugh’s claim is false. World temperatures measurements began in the 1800s and show a warming burst since the 1970s. Last year we checked with satellite scans of the ocean4, confirming the accuracy of the surface measurements. Global warming is measured fact. Working out the culprits has been like Crime Scene Investigation: Physics Edition. Some evidence comes from a facility in Billings, Oklahoma. Parts of air like water vapour and carbon dioxide naturally glow with infrared heat at very specific frequencies. The Billings site has a device that measured an incredibly precise “fingerprint” of the sky’s heating. Investigators reported in 20155 that they found fingerprints across the sky with a clear match on the heating trigger. Below the blue line is the file fingerprint for carbon dioxide (CO2) heating, which we release into the air when we do things like burn coal & oil. This file fingerprint comes from basic physics backed by precise lab readings. The red line is the measured fingerprint in the sky over Billings and is a rock solid match. Each spike is extra heat coming down from the extra CO2 molecules that is heating us up. Measurements in Alaska and from satellites6 confirm this. This is just one slide in the huge folder of empirical evidence showing human activity to be the main cause of recent warming. The fascinating results of this CSI: Physics Edition mean we can be confident beyond all reasonable doubt. Rush Limbaugh’s statement that there isn’t any “empirical evidence” has been false for years and years. The interesting question is in the ongoing episode: now we know who the main culprit is and have decided to let them lose, what will they do next? 1-Arrhenius (1896)On the Influence of Carbonic Acid in the Air upon the Temperature of the Ground,Philosophical Magazine and Journal of Science 2-Cook et al (2013)Quantifying the consensus on anthropogenic global warming in the scientific literature, Environmental Research Letters 3-Cook et al (2016)Consensus on consensus: a synthesis of consensus estimates on human-caused global warming, Environmental Research Letters 4- Hausfather et al (2017)Assessing recent warming using instrumentally homogeneous sea surface temperature records, Science Advances 5-Feldman et al (2015)Observational determination of surface radiative forcing by CO2 from 2000 to 2010, Nature 6-Harries et al (2001) Increases in greenhouse forcing inferred from the outgoing longwave radiation spectra of the Earth in 1970 and 1997, Nature Baird Langenbrunner Associate Editor, Nature Climate Change: This statement is completely wrong and misinformed. If Limbaugh really wanted to back up these claims, he would provide legitimate references, though unfortunately for him, they don’t exist. First, Limbaugh states that “there isn’t any warming,” though he doesn’t specify a time scale (Over the past decade? The past century? The entire history of Earth?), nor does he specify what physical property he’s talking about (his air-conditioned studio is probably not warming, but global surface temperatures, and ocean heat content, surely are increasing). It’s easy to claim something is false if one uses vague enough language. If we’re assuming he’s talking about Earth since the industrial revolution, when humans started ramping up fossil fuel burning, then he’s quite wrong. There has been very clear and measurable warming since this time period—this has been confirmed time and time again using station data and satellite measurements and it matches well with predictions based on increases in greenhouse gas concentrations. Even in the brief periods when the surface temperature warms less quickly, the oceans continue to warm, which together with the atmosphere accounts for all the extra heat predicted by increased greenhouse gas concentrations. This leads to the next part of the statement: “All they’ve got is computer model predictions, folks. There isn’t yet any empirical evidence for their claim that greenhouse gases even cause temperatures to increase. There isn’t any empirical data for that.” One thing that Limbaugh does seem to agree on is the fact that greenhouse gas concentrations are increasing, and that this is largely due to human activity. At least, he doesn’t reject this notion. But according to him, the direct link between these increases and Earth’s warming does not exist. Again, this is purely wrong. First, greenhouse gases are well studied, and their properties are nonnegotiable: They absorb and re-emit longwave radiation, whether they’re in a laboratory setting or in the real atmosphere. To back this up with historical evidence, scientists have known since the 1860s that CO2 is a greenhouse gas and since the 1890s that this will affect the heat budget of the Earth through warming. Even then, these claims were based on empirical evidence, and they’re supported by decades of laboratory research. Second, the link between increased greenhouse gas concentrations and warming continues to be supported by research in the last two decades. One study from 20011 used satellites to measure the type of energy entering and exiting Earth’s atmosphere and concluded that increases in greenhouse gases were responsible for extra heat measured between 1970 and 1997. The authors state that their results “provide direct experimental evidence for a significant increase in the Earth’s greenhouse effect that is consistent with concerns over radiative forcing of climate.” (Here, the term “radiative forcing” refers to the extra energy trapped in the atmosphere by greenhouse gases, cause warming.) A more recent study2arrived at similar conclusions, confirming predictions of the greenhouse effect in Earth’s atmosphere and providing “empirical evidence of how rising CO2 levels … are affecting the surface energy balance.” In other words, rising CO2 was linked directly to warming, even when things like plant uptake of CO2 were considered. Finally, while climate models do confirm these predictions, they’re not needed. Limbaugh states that scientists only have computer model predictions to back up these claims, but models are merely one aspect of a large set of tools that provide evidence for anthropogenic global warming. Limbaugh’s claims are wrong, and there’s really no way to spin them to be correct. 1-Harries et al (2001) Increases in greenhouse forcing inferred from the outgoing longwave radiation spectra of the Earth in 1970 and 1997, Nature 2-Feldman et al (2015)Observational determination of surface radiative forcing by CO2 from 2000 to 2010, Nature Shaun Lovejoy Professor, McGill University: [This comment is taken from an earlier review of a similar claim.] Let’s say you are given only three pieces of information: a) The annual average value of the global temperature from 1880 to 1909 b) The atmospheric CO2 concentration for each year c) The effective climate sensitivity With only this, the temperature over the 104 years between 1909 and 2013 could be incredibly well forecast (black line in the figure below), indeed to about an accuracy of ±0.22 °C (purple lines, 90% confidence limits). This tight limit includes the so-called “pause” of the early 2000s. Knowing only the CO2 therefore allows us to predict the temperature more than 100 years into the future. Given that the total change over this time was 1.1 °C, the prediction is correct to within 20%. We know that the CO2 was anthropogenic, therefore its increase was not caused by a change of temperature. We can conclude that CO2 is responsible for much of the change in temperature over the last century. Figure adapted from Lovejoy (2015), Using scaling for macroweather forecasting including the pause, Geophysical Research Letters"
https://science.feedback.org/review/washington-post-accurately-covers-permafrost-study-albeit-under-a-somewhat-sensational-headline-chris-mooney/,2,"The Washington Post, by Chris Mooney, on 2018-03-19.",,"""The Arctic’s carbon bomb might be even more potent than we thought""",,,,,"This article in The Washington Post describes new research on greenhouse gas emissions from thawing permafrost—specifically the balance of carbon dioxide vs. methane released from waterlogged permafrost soils. Scientists who reviewed the article found that it accurately described the study and provided context on its overall implications by quoting comments from two other researchers. The article’s headline, however, may mislead readers through the use of the sensational phrase “the Arctic’s carbon bomb”, which calls to mind a catastrophic, explosive release of greenhouse gas. The study could indicate that more of the carbon released from thawing permafrost will be released as methane—increasing its near-term warming influence—but it is not clear how much additional methane this would represent.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Benjamin Stocker Postdoctoral research fellow, Centre for Research on Ecology & Forestry Applications (CREAF), Spain: Although the title of this article (“bomb”) may overstate the implications of the new research referred to here, the main text accurately portrays the recently published article by Knoblauch et al, its implications, and remaining uncertainties. The additional statements about the impact and caveats of new findings, given by different researchers, makes this Washington Post article credible and informative. Andrew MacDougall Assistant Professor, St. Francis Xavier University: The article does a very good job summarizing what is new about the research while also pointing out the main caveats of the study. The title is a bit over-dramatic but the content is accurate. Charles Koven Staff Scientist, Lawrence Berkeley National Lab: The article accurately described an interesting new piece of research and how it was done, how the new research fit into a larger debate in the permafrost carbon community, and offered a balanced pair of perspectives on whether the findings of the new research actually shifted the terms of that debate. Well done! Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Annotations: The statements quoted below are from the article; comments and replies are from the reviewers. “The Arctic’s carbon bomb might be even more potent than we thought […] methane, a shorter-lived but far harder-hitting gas that could cause faster bursts of warming” Benjamin Stocker Postdoctoral research fellow, Centre for Research on Ecology & Forestry Applications (CREAF), Spain: This wording suggests that permafrost melt in the Arctic is an abrupt event. Even the new research referred to here doesn’t put earlier work* fundamentally into question that argued for “a gradual and prolonged release of greenhouse gas emissions in a warming climate”. Shuur et al (2015) Climate change and the permafrost carbon feedback, Nature “For some time, scientists fearing the mass release of greenhouse gases from the carbon-rich, frozen soils of the Arctic have had at least one morsel of good news in their forecasts: They predicted most of the gas released would be carbon dioxide” Andrew MacDougall Assistant Professor, St. Francis Xavier University: This is true and is still true given the results of the Knoblauch et al paper*. Most of the gas released will be CO2, but since gram-for-gram CH4 is much stronger greenhouse gas, the warming effect may be more dominated by CH4 than previous studies suggested. Knoblauch et al (2018) Methane production as key to the greenhouse gas budget of thawing permafrost, Nature Climate Change “the researchers calculated that the impact of greenhouse gas emissions from wet soils, or wetlands, will be higher than from drier soils[…] This finding, if further confirmed, could reorient calculations of the overall potential of permafrost to worsen global warming over the coming century.” Andrew MacDougall Assistant Professor, St. Francis Xavier University: The statement is true and properly cautious about the results of the Knoblauch et al paper. The article could have included that the present estimate* for additional warming from the permafrost carbon feedback is on the order of 0.13–0.27 °C to give a more quantitative sense of the strength of the feedback. Shuur et al (2015) Climate change and the permafrost carbon feedback, Nature “more research would have to be done to go from these results to a forecast for just how much methane could waft from permafrost in the coming decades. It will be important to know, for instance, how much thawed permafrost will be stuck in watery conditions vs. dry ones.” Andrew MacDougall Assistant Professor, St. Francis Xavier University: This is accurate."
https://science.feedback.org/review/financial-post-publishes-misleading-opinion-misrepresents-science-polar-bears-peril-susan-crockford/,-1.7,"Financial Post, by Susan Crockford, on 2018-02-27.",,"""Polar bears keep thriving even as global warming alarmists keep pretending they’re dying""",,,,,"This article in the opinion section of Financial Post, written by Susan Crockford, claims that rather than being threatened by declining Arctic sea ice, polar bears are “thriving”. Three scientists who reviewed the article explained that this article fundamentally misrepresents research on the topic. The author exhibits poor reasoning in arguing that polar bear population loss projected for 2050 should have occurred already if that science was accurate. Researchers do not ignore the evidence Crockford claims they do, but instead incorporate all published research on polar bear populations. Despite the article’s statements to the contrary, research shows that polar bear populations will struggle as ice-free periods (during which they cannot hunt for food) grow longer.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Andrew Derocher, Professor, University of Alberta: The article is nonsense and reflects a profound lack of understanding of polar bear ecology, ringed seal ecology, Arctic marine ecosystem, and sea ice. Cody Dey, Postdoctoral Fellow, University of Windsor: The article cherry picks scientific results and does not consider the total weight of scientific evidence which clearly indicate that polar bears are negatively affected by sea ice loss. Steven Amstrup Chief Scientist, Polar Bears International, and Adjunct Professor University of Wyoming in Laramie: The article is composed of misstatements. These are either based upon the author’s apparent lack of understanding of the ecological and geophysical situations, or intent to mislead readers. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Annotations: The statements quoted below are from the article; comments and replies are from the reviewers. “Although the extent of the summer sea ice after 2006 dropped abruptly to levels not expected until 2050, the predicted 67-per-cent decline in polar bear numbers simply didn’t happen. Rather, global polar bear numbers have been stable or slightly improved.” Steven Amstrup Chief Scientist, Polar Bears International, and Adjunct Professor University of Wyoming in Laramie: This blogger has repeatedly criticized polar bear projections because what we predicted for mid-century has not yet happened. Most of the climate model projections for sea ice decline show summer ice down to near zero by mid century and they all converge on zero by the end of the century. None of the mainstream models of which I am aware project that summer ice would be gone by now. Of course summer ice availability has been reduced from earlier years, but neither observations nor models suggest that what we predicted for mid century has already happened. Here is an image that may help put this in perspective, and make it clear why our projections focused on mid century and beyond, and that we are not yet in mid-century: Andrew Derocher, Professor, University of Alberta: This is nonsense. No polar bear scientist has predicted a drop in polar bear abundance based on summer sea ice. We base the assessment of loss on duration of the ice-free period. Papers1,2 from our research group assess this point. The statement about global polar bear numbers is absolutely unfounded. It is a contrived statement using population estimates provided so that children (or the general public) could give a number of polar bears in the world for school reports and the like. Castro de la Guarida1 states, “Sea ice across the Arctic is declining and altering physical characteristics of marine ecosystems. Polar bears (Ursus maritimus) have been identified as vulnerable to changes in sea ice conditions. We use sea ice projections for the Canadian Arctic Archipelago from 2006 – 2100 to gain insight into the conservation challenges for polar bears with respect to habitat loss using metrics developed from polar bear energetics modeling. PRINCIPAL FINDINGS: Shifts away from multiyear ice to annual ice cover throughout the region, as well as lengthening ice-free periods, may become critical for polar bears before the end of the 21st century with projected warming. Each polar bear population in the Archipelago may undergo 2-5 months of ice-free conditions, where no such conditions exist presently. We identify spatially and temporally explicit ice-free periods that extend beyond what polar bears require for nutritional and reproductive demands. CONCLUSIONS/SIGNIFICANCE: Under business-as-usual climate projections, polar bears may face starvation and reproductive failure across the entire Archipelago by the year 2100.” Both of these studies1,2 assess the threat to polar bears based on projected sea ice loss over the next 3 generations (ca. 33-45 years). It is an issue of fasting duration that causes polar bear population declines and this is well understood in the published literature. Dr. Crockford is following the standard climate change denier approach of picking on a specific detail and then contriving an unsubstantiated fictional account on that point. Loss of sea ice in summer is, by and large, irrelevant. It’s the duration of the ice-free period that matters. If not, polar bears in Hudson Bay would have disappeared hundreds or thousands of years ago but they didn’t because they used to be able to obtain sufficient fat stores while hunting seals on the sea ice in spring. The situation is changing but the best estimate is that we’ll have significant declines in the Western Hudson Bay population (beyond the current ca. 30% decline) by mid-century. By repeating it often enough, it appears that deniers or the uninformed think there’s some merit to the issue Dr. Crockford has raised. Nobody can scientifically rebut the flawed thesis because it isn’t published. My understanding was that the manuscript was rejected by scientific journals so now Dr. Crockford’s manuscript languishes as an unreviewed “Preprint” in PeerJ and she erroneously calls it a “paper”. 1- Castro de la Guardia et al (2013) Future sea ice conditions in western Hudson Bay and consequences for polar bears in the 21st century, Global Change Biology 2- Regehr et al (2016) Conservation status of polar bears (Ursus maritimus) in relation to projected sea-ice declines, Biology Letters “For example, Canadian polar bear biologist Ian Stirling learned in the 1970s that spring sea ice in the southern Beaufort Sea periodically gets so thick that seals depart, depriving local polar bears of their prey and causing their numbers to plummet. But that fact, documented in more than a dozen scientific papers, is not discussed today as part of polar bear ecology.” Steven Amstrup Chief Scientist, Polar Bears International, and Adjunct Professor University of Wyoming in Laramie: Both Ian Stirling and I have published on the inter-annual and even multi-annual variation in sea ice extent, etc. There is a great deal of annual variation among years, as always. And as the observations and models illustrate, the variation (caused by the natural chaos in the climate system) that always has been observed will continue into the future. Ian specifically mentioned in some early publications that there seemed a nearly decadal oscillation in ice thickness, etc. Ideal habitat for polar bears and ice loving seals (like all animals) follows a kind of bell-shaped curve. Ice can be too thick and heavy, just right, or too thin (which also means it doesn’t persist long during the melt season). Most of those early years there was plenty of ice that persisted through the summer in the Beaufort Sea. Even most light ice years had enough ice there to not be a problem. Some years (and seemingly on about 10 year intervals) were characterized by ice that was apparently too heavy to be ideal for seals and bears, and in those years productivity of both declined. It is important to point out that the concept of an approximate 10-year oscillation was based on 3 decades (70s, 80s, and 90s) and a sample size of 3 may not really be enough to establish some kind of natural cycle. Regardless, as the world has warmed and ice continued to thin, evidence of any such cycle in the Alaskan Beaufort has disappeared. We did not see a crush of heavier ice in the middle of the first or second decades of the 2000s. Rather, the situation now is that ice is thin every year and has not persisted through the melt season in the critical continental shelf waters. Why would researchers spend much time now discussing a pattern in the sea ice that no longer rises to historic levels? Whether they are part of a larger scale oscillation or more regional weather patterns, year to year and multi-year differences in the amount of sea ice and its character are part of the natural variation in the climate system that will continue as the world warms due to human activity. Global warming doesn’t mean that every year will be a bit warmer than the previous or that the sea ice extent will be a bit lower. Rather it means that the average of the natural variations over multiple years is and will continue to be warmer temperatures and less sea ice. Without persistent greenhouse gas rise, the historic averages of natural variations in global temperature and Arctic sea ice extent were approximately horizontal baselines—both temperature and sea ice extent were without major trend when examined over decades. With persistently rising greenhouse gas levels all of the natural variation still occurs, but now occurs over inclined rather than level baselines. With greenhouse gas levels constantly rising, there still are near-term fluctuations in annual and seasonal temperatures. Some years warmer and some cooler than the one before, but the average over decades is a rising trend line. Likewise, some years have had and will have more summer ice than the previous year, and some less. Whether those short term variations in Arctic sea ice extent are due to annual weather influences or multi-year cycles driven by broader oceanic patterns, they are now and will continue to be occurring over a declining baseline as long as greenhouse gas levels continue to rise. Hence, it is not the swings in individual years or groups of years, but rather the trend line that is our concern. And as long as greenhouse gas concentrations continue to rise, average temperatures can only increase and average sea ice extent can only decline. The average Arctic summer sea ice extent already is so far below the historic levels that recent short term fluctuations have not overlapped with levels of just a few decades ago. Hence, what might have been called relatively “heavier” ice years are now light years by historic standards. Andrew Derocher, Professor, University of Alberta: Sea ice conditions are well document to be in steep decline in the southern Beaufort Sea. This polar bear population has declined 25-50% and the loss is related to sea ice loss. There are many papers that address this issue extensively. Heavy sea ice conditions are largely a past issue for ringed seals. It is loss of sea ice habitat as a whole that is negatively affecting ringed seals and thus polar bears. Polar bears have a Goldilocks relationship with sea ice: not too much, not too little, it has to be just right. Dr. Crockford is playing the “too much” sea ice issue to its extreme and ignores the too little aspect altogether. These two papers1,2 are core but there are many more addressing sea ice loss in the Beaufort and the effects on polar bears. 1- Bromaghin et al (2015) Polar bear population dynamics in the southern Beaufort Sea during a period of sea ice decline, Ecological Applications 2- Hunter et al (2010) Climate change threatens polar bear populations: a stochastic demographic analysis, Ecology “many scientists were surprised when other researchers subsequently found that ringed and bearded seals (the primary prey of polar bears) north of the Bering Strait especially thrived with a longer open-water season, which is particularly conducive to fishing” Steven Amstrup Chief Scientist, Polar Bears International, and Adjunct Professor University of Wyoming in Laramie: The Chukchi sea is essentially all continental shelf and is probably the most productive of the Arctic Seas. This is in contrast to the Beaufort Sea which, beyond the very narrow continental shelf, is very unproductive. Recent research has shown that this tremendous productivity and the fact that, although ice has significantly retreated, bears there still have fewer ice free days over the shelf than in the Beaufort, can explain why Chukchi Sea polar bears have not yet declined like those in the Beaufort. Andrew Derocher, Professor, University of Alberta: Both ringed seals and bearded seals are sea ice obligate species: there are significant conservation concerns about both species across the Arctic. The basis of the statement that the seals are thriving is unfounded in the peer-reviewed literature. Both species are listed under the US Endangered Species Act. The polar bears living north of the Bering Strait have not shown the same loss in body condition, survival, and reproduction noted in the neighboring Beaufort Sea because the ecosystems are vastly different in the distribution of continental shelf habitat: huge area in the Chukchi Sea, a narrow band in the Beaufort. Polar bear populations respond to local changes, and with 19 polar bear populations, there will be 19 different scenarios playing out over time. Loss of sea ice in the Chukchi Sea in winter 2017/18 may change the situation there. “while it’s true that studies in some regions show polar bears are lighter in weight than they were in the 1980s, there is no evidence that more individuals are starving to death or becoming too thin to reproduce because of less summer ice.” Steven Amstrup Chief Scientist, Polar Bears International, and Adjunct Professor University of Wyoming in Laramie: We know that polar bears depend on the ice surface to catch their prey. We know that increasing numbers of ice free days have resulted in poorer body condition in some areas (e.g. Southern Beaufort, Western and Southern Hudson Bay), we know that poorer cub survival has followed both declining ice and poorer body condition, and all the evidence suggests these things are linked. Perhaps this is not “proof” that less available summer ice is the cause (correlation does not necessarily imply causation), but I am not aware of evidence for any other explanation. And I don’t think the female polar bears are intentionally having cubs but not feeding them. Andrew Derocher, Professor, University of Alberta: There is evidence. Bromaghin et al 20151 and Hunter et al 20102 examine this issue. Bromaghin et al state, “Low survival from 2004 through 2006 led to a 25–50% decline in abundance. We hypothesize that low survival during this period resulted from (1) unfavorable ice conditions that limited access to prey during multiple seasons; and possibly, (2) low prey abundance. For reasons that are not clear, survival of adults and cubs began to improve in 2007 and abundance was comparatively stable from 2008 to 2010, with ~900 bears in 2010 (90% CI 606–1212). However, survival of subadult bears declined throughout the entire period. Reduced spatial and temporal availability of sea ice is expected to increasingly force population dynamics of polar bears as the climate continues to warm. However, in the short term, our findings suggest that factors other than sea ice can influence survival.” Hunter et al stated, “Deterministic models projected population growth in years with more extensive ice coverage (2001-2003) and population decline in years with less ice coverage (2004-2005). LTRE (life table response experiment) analysis showed that the reduction in lambda in years with low sea ice was due primarily to reduced adult female survival, and secondarily to reduced breeding. A stochastic model with two environmental states, good and poor sea ice conditions, projected a declining stochastic growth rate, log lambda(s), as the frequency of poor ice years increased. The observed frequency of poor ice years since 1979 would imply log lambda(s) approximate to -0.01, which agrees with available (albeit crude) observations of population size. The stochastic model was linked to a set of 10 GCMs compiled by the IPCC; the models were chosen for their ability to reproduce historical observations of sea ice and were forced with “business as usual” (A1B) greenhouse gas emissions. The resulting stochastic population projections showed drastic declines in the polar bear population by the end of the 21st century. These projections were instrumental in the decision to list the polar bear as a threatened species under the U. S. Endangered Species Act.” 1- Bromaghin et al (2015) Polar bear population dynamics in the southern Beaufort Sea during a period of sea ice decline, Ecological Applications 2- Hunter et al (2010) Climate change threatens polar bear populations: a stochastic demographic analysis, Ecology “The failure of the 2007 polar bear survival model is a simple fact that explodes the myth that polar bears are on their way to extinction.” Steven Amstrup Chief Scientist, Polar Bears International, and Adjunct Professor University of Wyoming in Laramie: Multiple papers published subsequent to my work in 2007 have corroborated the outcomes we projected. However, the accuracy or failure of my work to inform the Secretary of Interior* cannot be evaluated until mid century. And as the figure above shows, we are not there yet. Amstrup et al (2010) Greenhouse gas mitigation can reduce sea-ice loss and increase polar bear persistence, Nature"
https://science.feedback.org/review/satellite-measurements-accelerating-sea-level-rise-cnn-accurately-reports-brandon-miller/,1.5,"CNN, by Brandon Miller, on 2018-02-13.",,"""Satellite observations show sea levels rising, and climate change is accelerating it""",,,,,"This article at CNN reports on a new study that calculates the acceleration of sea level rise that has become apparent in the record of satellite measurements, which began in 1993. Because the satellite record is so short, this acceleration has not been clear until recently. Figure – Global mean sea level (blue), after removing an estimate for the impacts of the eruption of Mount Pinatubo (red), and after also removing the influence of El Niño (green), fit with a quadratic (black). The acceleration is 0.084 mm/y2. FromNerem et al. (2018) Scientists who reviewed the article found that it described the study accurately. The article could have clarified for context that many studies have analyzed sea level rise trends in tide gauge data going back to the early 20th century.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Keven Roy Research Fellow, Nanyang Technological University: This is, in general, a good article that represents quite well the message from the study under discussion, with only a few statements that could have been clarified. However, I think that the article would have gained from placing the study in a better context, as there have been other data-based assessments of 21st century sea level rise1,2 (process-based or statistical). A comparison to assessments of modern sea level rise that included tide gauge data3 would have been useful too. 1-Jackson and Jevrejeva (2016) A probabilistic approach to 21st century regional sea-level projections using RCP and High-end scenarios, Global and Planetary Change 2-Kopp et al (2017)Evolving Understanding of Antarctic Ice-Sheet Physics and Ambiguity in Probabilistic Sea-Level Projections, Earth’s Future 3-Hay et al (2015)Probabilistic reanalysis of twentieth-century sea-level rise, Nature Ernst Schrama Associate Professor, Delft University of Technology: I think this article accurately presents what we see in the satellite and tide gauge data. The wording “the projection agrees perfectly with climate models” is maybe somewhat strong. One could say the observation data is consistent with climate models. Benjamin Horton Professor, Earth Observatory of Singapore: Global geological sea-level data from the Common Era (last 2000 years), global sea-level data from tide gauge records since 1880 and now satellite sea-level data from 1993 all show that the rate of sea level rise is accelerating. These accelerations in sea level is a cause for great concern. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Annotations: The statements quoted below are from the article; comments and replies are from the reviewers. “Using satellite data rather than tide-gauge data that is normally used to measure sea levels allows for more precise estimates of global sea level, since it provides measurements of the open ocean.” Keven Roy Research Fellow, Nanyang Technological University: This may be a bit of a misrepresentation, as precision is only one part of the story here. The length of the available records is also crucial—hence the need for studies of tide gauge data. Benjamin Horton Professor, Earth Observatory of Singapore: Global geological sea-level data from the Common Era (last 2000 years), global sea-level data from tide gauge records since 1880 and now satellite sea-level data from 1993 all show that the rate of sea level rise is accelerating. These accelerations in sea level is a cause for great concern. As the satellite altimetry record length grows so does the satellite derived time series of (near) global mean sea surface height. Putting recent estimates of GMSL, 2.6-3.2 mm/yr, into historical context is an important and daunting task, and is necessary in order to quantify sea-level accelerations, both regionally and globally. This CNN article highlights the importance of Nerem’s excellent paper. “Sea level rise of 65 centimeters, or roughly 2 feet would cause significant problems for coastal cities around the world.” Keven Roy Research Fellow, Nanyang Technological University: It should be mentioned that this is a global average. The increase will not be uniform—exacerbating the consequences described below. Benjamin Horton Professor, Earth Observatory of Singapore: But there is one caveat that I would like to bring up, whether sea level showed an acceleration or not in the satellite era is of less importance compared to the rates of rise we will have to endure in the remainder of the 21st century (and beyond). Predictions of future sea level rise should be based on physics, not statistics. Statistics simply doesn’t enable us to foresee the future beyond a very brief window of time. Even given the observed acceleration in the satellite era, the forecasts we should attend to are not from statistics but from physics. “Therefore, scientists now have observed evidence validating climate model projections” Keven Roy Research Fellow, Nanyang Technological University: I think this is a strong statement. The authors are not validating model predictions against observations—they are comparing model predictions to an extrapolation obtained from 25 years of data. “Theirs is a troubling finding when considering the recent rapid ice loss in the ice sheets. ‘Sixty-five centimeters is probably on the low end for 2100,’ Nerem said, ‘since it assumes the rate and acceleration we have seen over the last 25 years continues for the next 82 years.’” Keven Roy Research Fellow, Nanyang Technological University: This is an important point, and it is good to see it mentioned in the article."
https://science.feedback.org/review/president-trumps-claim-growing-ice-not-reflect-reality/,Inaccurate,"ITV, Donald Trump, 2018-01-28","The ice caps were going to melt. They were going to be gone by now, but now they're setting records",,"Factually inaccurate: Arctic sea ice and the ice sheets of Greenland and Antarctica are setting record lows as they decline—not record highs. Antarctic sea ice has also been quite low in the last few years, but is naturally more variable from year to year. Imprecise: The term “ice caps” makes it unclear what President Trump intends to refer to. An ice cap is one technical category of glacial ice on land, not a catch-all term for polar sea ice and glaciers..","Human-induced warming at the poles has caused a reduction in sea ice extent, notably in the Arctic, and a continuous shrinking of glaciers on land. President Trump has probably been misled by inaccurate articles like this one published by Forbes.","There is a cooling and there's a heating -- I mean, look, it used to not be climate change. It used to be global warming. That wasn't working too well because it was getting too cold all over the place. The ice caps were going to melt. They were going to be gone by now, but now they're setting records, okay? They're at a record level.",,"Emma Boland Physical Oceanographer, British Antarctic Survey: This claim is misleading in the extreme—the ice caps are indeed setting records, but not in the way President Trump is implying. The USA’s own National Snow and Ice Data Center shows that December 2017 was the second lowest December extent on record for Arctic sea ice extent (see below), and the Greenland ice sheet continues to set record lows (see below). Antarctica is also losing land ice, and at an accelerating rate*. Shepherd et al (2012)A Reconciled Estimate of Ice-Sheet Mass Balance, Science François Massonnet Postdoctoral Research Fellow, Université catholique de Louvain: President Trump uses the wording “ice caps”. This wording itself is not precise, as defined in the American Meteorological Society glossary—it is not clear whether President Trump is referring to ice sheets, sea ice, or glaciers. Given the start of the next sentence, I assume he is referring to sea ice. On the statement that “They [ice caps, meaning sea ice as I understand him] were going to be gone by now”: To my knowledge, only two scientists (P. Wadhams and M. Maslowski) predicted that an ice-free Arctic would have already occured in summer by now (but this has obviously not been the case). [Previous Climate Feedback evaluations have rated the credibility of Wadhams’ claim.] Both statements were made by extrapolating the observed record and model output, respectively. This method ignores (1) the existence of powerful negative feedbacks that make the ice grow faster when it is thinner1, and (2) the existence of strong interannual variability that interplays with the long-term decline2. A thorough assessment of the scientific literature carried out in the latest IPCC report reveals that the Arctic is likely to become ice-free in summer by mid-century. On the statement that “They are setting records”: Yes, they are, but they are setting record lows. Given the first part of his sentence, I assume that President Trump meant “record highs”, so he is wrong. Global sea ice extent (Arctic + Antarctic) has been lowest in 2016 and 2017 compared to the historical record. Arctic sea ice extent has been declining for decades. Antarctic sea ice extent displayed moderate increases from 1979 to 2014 but has considerably decreased since then. 1- Bitz and Roe (2004)A Mechanism for the High Rate of Sea Ice Thinning in the Arctic Ocean, Journal of Climate 2- Swart et al (2015)Influence of internal variability on Arctic sea-ice trends, Naure Climate Change Twila Moon Research Scientist, University of Colorado, Boulder: No part of this statement is true. Regarding the specific claim about ice sheets, this is false. The large ice sheets or ice caps do not have more ice now than they would have without human-caused climate change. The opposite is true—the world’s ice sheets and glaciers have less ice because of human-caused climate change. The Greenland and Antarctic Ice Sheets and glaciers and other large ice areas (e.g. in Alaska, Canada, Patagonia, Himalayas, etc.) are collectively losing hundreds of gigatons of ice per year and directly raising ocean levels, among other impacts. There is a small mountain of research on ice sheet behavior, which all clearly points to ice loss due to human-caused change. For evidence that human-caused warming is the main factor in glacier ice loss, Roe et al is a good reference*. The issue of “climate change” versus “global warming” is only a topic of word choice and in no way reflects a changes in the patterns of ice behavior that scientists are observing worldwide. Nature does not care about word choice. Roe et al (2017)Centennial glacier retreat as categorical evidence of regional climate change, Nature Geoscience Nathanael Melia Postdoctoral research fellow, University of Reading: President Trumps comments that “The ice caps were going to melt. They were going to be gone by now” may be the result of predictions made a few years ago by an overly enthusiastic Arctic scientist who I choose not to name here. At the time the climate science community rejected such extreme predictions, however the headlines stuck and return here to the detriment of the community and the planet. It is not clear whether presidents Trump’s comments on record setting are intentionally ambiguous, but one can assume he feels they are at record high levels based on the context. According to NASA data, Land Ice in Antarctica has lost 2000 Gt in the last 15 years, while the Greenland ice sheet has lost almost 4000 Gt over that period. As far as sea ice is concerned both the Arctic and Antarctic are currently (Jan 2018) running at a negative extent anomaly, which combined totals to -2,439,000 km2 using NSIDC data, trends in sea ice thickness and volume are even greater. President Trump also mentions there’s cooling and there’s heating. This is somewhat true and is the natural variability of the climate. The trouble is that human influence means that on average we now see a lot more heating than cooling, a trend we don’t expect to change anytime soon."
https://science.feedback.org/review/national-geographic-video-starving-polar-bear-should-have-clarified-uncertain-link-climate-change-sarah-gibbens/,0.3,"National Geographic, by Sarah Gibbens, on 2017-12-07.",,"""Heart-Wrenching Video Shows Starving Polar Bear on Iceless Land""",,,,,"This widely-shared December 2017 article at National Geographic featured emotional footage of a starving polar bear, highlighting the plight of polar bears as the extent of Arctic sea ice declines. Scientists who reviewed the article explained that the connection to climate change should have been explained more carefully. While polar bears will face more difficulties reaching prey as Arctic sea ice continues to diminish, it is also true that starvation is a common natural cause of death for polar bears. It is not known whether this polar bear’s death was a result of human-caused sea ice conditions, even if it does provide a visceral example of the fate many polar bears will suffer due to climate change. UPDATE (27 July 2018): National Geographic has updated their article with the following note: “The text on the video above was edited on June 1, 2018 to make it clear that it is impossible to know why the polar bear pictured was starving. An earlier version of the video went too far in suggesting that climate change was responsible (read more).”See all the scientists’ annotations in context This is part of a series of reviews of 2017’s most popular climate stories on social media. GUEST COMMENTS: Karen Lone, Research Scientist, Norwegian Polar Institute: The article contains valid information on the devastating consequences of climate change on polar bears. The only problem as I see it is that the article presents (implicitly) that the polar bear in the video is dying as a consequence of climate change and from not finding enough food due to lack of sea ice. This issue that this bear might be dying from starvation naturally due to sickness or old age should be stated more clearly in the article (and this concern has been raised in the media, by experts, already). The only flawed reasoning is the strong IMPLICIT link between climate change and the death of this particular bear in the video. However, the wording used in the article, “this is what is starving polar bear looks like…” is true. While it could be presented better in this (central) aspect, the article’s content, overall, is credible. Steven Amstrup Chief Scientist, Polar Bears International, and Adjunct Professor University of Wyoming in Laramie: This reveals what declining survival looks like for polar bears, a trend we will see increase as the world warms. But the article neglected to point out this bear’s problems may or may not have had much to do with declining sea ice in the Baffin area—an error of omission that can become a target of global warming deniers. The important lesson from the observations shown is that ever-more polar bears will be suffering this kind of fate as we allow the world to continue to warm. Largely by omission, this article suggests we know what led to this bear’s demise, and we don’t. Starvation is the main cause of death among wild polar bears. After all, they have few natural predators. Starvation rates will increase (decreased survival rates) as sea ice continues to decline. But we must be careful in presenting an observation like this as the fingerprint of climate warming. Without proper context, observations and stories like this can distract from the critical message we need to get out. REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Stephen Hamilton PhD Candidate, University of Alberta: The 2002 WWF report and NSIDC findings cited would be better replaced with peer-reviewed literature, of which there are many high-quality and more modern choices. Furthermore, there is good work done on polar bear energetic needs and how land-based nutrition is insufficient for their diet*. The title’s inclusion of “iceless land” could give the impression that being on land is the cause of starvation in itself. Nevertheless, the article correctly mentions that it is not uncommon for bears to fast for months. Rode et al (2015) Can polar bears use terrestrial foods to offset lost ice-based hunting opportunities?, Frontiers in Ecology and the Environment Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time."
https://science.feedback.org/review/atlantic-climate-implications-reduced-beef-consumption-provide-clearer-context-james-hamblin/,0.3,"The Atlantic, by James Hamblin, on 2017-08-02.",,"""If Everyone Ate Beans Instead of Beef""",,,,,"This August 2017 article in The Atlantic covered a study of the greenhouse gas emissions that could be avoided if beef consumption was reduced in the United States. Beef is a particularly resource-intensive food, due in part to the fact that the conversion of plant foods into beef is much less efficient than obtaining calories and protein from plants directly. Scientists who reviewed the article were divided. While the article summarizes the main points of the paper effectively, some of the context provided is incomplete or potentially misleading. The carbon footprint of dietary choices is a complex topic that can be easily oversimplified, making context critical.See all the scientists’ annotations in context This is part of a series of reviews of 2017’s most popular climate stories on social media.GUEST COMMENTS: Gidon Eshel Research professor, Bard College: [Prof. Eshel was an author of the study described in this article.] The story basically relays well the crux of the paper. Simple and to the point, with not much to complain about… Alejandro Gonzalez Research Scientist, National Research Council-Argentina (CONICET): The article is strongly misleading the reader, who at first gets the impression that all beef eaten is from Brazil, which is totally false. Imports account for around 12% of beef consumed in the US, and Brazil contributes with only 5% of imports, while Australia, Canada, New Zealand and Mexico provide 86% of beef imported (see ERS-USDA webpage). Thus, lowering beef consumption in the US is far from affecting Brazilian forests. On the other hand, it is not true that eliminating beef from diets will produce such reductions in GHG emissions. The author cites conclusions from a single work, but there are hundreds of works published on diet and mitigation of climate change. The consensus is that a well-planned diet change would lower greenhouse gas emissions, but none agree that banning a single product would bring any benefit. Not only beef but all animal products are much less efficient than plant-based ones, and meats other than beef also carry environmental burdens beyond greenhouse gases. The article is very bad—it mixes up sensational keynotes, climate-forest-Trump-beef-Brazil-efficiency-Paris agreement, in a rather random fashion, likely intending to shock the reader and cause excitement. REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Alexis Berg Research Associate, Harvard University: The article reports in a straightforward way on a scientific paper about the potential reductions in greenhouse gas emission in the US resulting from substituting beans for beef. The article explains the issue (meat production diverts crops from humans to cattle) on a simple level. More explanation and more context could have been provided, I think, regarding individual-level and sectoral sources of greenhouse emissions. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Annotations: The statements quoted below are from the article; comments and replies are from the reviewers. “Recently Harwatt and a team of scientists from Oregon State University, Bard College, and Loma Linda University calculated just what would happen if every American made one dietary change: substituting beans for beef.” Ana Bastos Group Leader, Max Planck Institute for Biogeochemistry: Beans have a carbon footprint between 1-2 kilograms of CO2 equivalent per kilogram, while values for beef range 9-129*. Since they differ in their energy and protein content, the authors of this study calculated separately the CO2 emissions resulting from replacing beans for beef for the same amount of energy or proteins. Nijdamet et al (2012) The price of protein: Review: of land use and carbon footprints from life cycle assessments of animal food products and their substitutes, Food Policy “and even if people kept eating chicken and pork and eggs and cheese” Alexis Berg Research Associate, Harvard University: A significant share of beef supply in the US comes from dairy cows (around 20% I think)—typically, as processed meat. So switching beef for beans would likely affect the dairy sector as well. “this one dietary change could achieve somewhere between 46 and 74 percent of the reductions needed to meet the target.” Alexis Berg Research Associate, Harvard University: That target should be described explicitly: -17% of greenhouse gas emissions compared to 2005 levels, by 2020. Given that emissions have been decreasing since 2005 (in no uncertain part because of the economic crisis of 2008)—which was already obvious when the Obama Administration made that pledge in 2009—what is needed is a further 7% decrease compared to 2013 levels (according to the authors of the paper cited in this article). Note, this target is much less than the Paris Agreement: -27% by 2025. “more so than downsizing one’s car, or being vigilant about turning off light bulbs, and certainly more than quitting showering.” Alexis Berg Research Associate, Harvard University: To be honest, the action listed here are rather trivial. I don’t think anybody reasonable is advocating for people to stop showering all together to conserve energy (that’s not even the rationale of the article linked to). Maybe a more relevant comparison would be against individual carbon emissions from flying, which for people who fly a lot can represent a large part of their footprint. “Which is to say that these beans will be eaten by cows, and the cows will convert the beans to meat, and the humans will eat the meat. In the process, the cows will emit much greenhouse gas, and they will consume far more calories in beans than they will yield in meat, meaning far more clearcutting of forests to farm cattle feed than would be necessary if the beans above were simply eaten by people.” Alexis Berg Research Associate, Harvard University: It would be nice to explain the source of these emissions (methane production, manure management, etc.). Ana Bastos Group Leader, Max Planck Institute for Biogeochemistry: Even compared to other meat products, beef has additionally lower meat yield, i.e. the weight of meat produced per kg of live weight*1, and lower energy efficiency (lower energy output per energy input*2). 1- Nijdamet et al (2012) The price of protein: Review of land use and carbon footprints from life cycle assessments of animal food products and their substitutes, Food Policy 2- Eshel and Martin (2005) Diet, Energy, and Global Warming, Earth Interactions “Even more, 26 percent of the ice-free terrestrial surface of Earth is used for grazing livestock.” Alexis Berg Research Associate, Harvard University: Note that some of this corresponds to marginal lands that wouldn’t necessarily be well suitable for crops, and it could be argued that over such land it would make sense to raise cattle. “focusing on where efforts will have the highest yield” Alexis Berg Research Associate, Harvard University: While there is no doubt that not eating beef would reduce greenhouse gas emissions and may be one the single most efficient individual actions (along with less flying/driving), it’s worth keeping in mind that, according to the EPA, the agricultural sector represents only 9% of US greenhouse gas emissions. (That number is higher world wide—around ~20%—presumably because other source of emissions are also very high in the US…) Source"
https://science.feedback.org/review/new-york-times-iceberg-larsen-c-size-delaware-jugal-patel-justin-gillis/,1.7,"The New York Times, by Jugal K. Patel, Justin Gillis, on 2017-07-12.",,"""An Iceberg the Size of Delaware Just Broke Away From Antarctica""",,,,,"This July 2017 article in The New York Times described a remarkable iceberg calving event at Antarctica’s Larsen C ice shelf. Scientists who reviewed the article found it to be essentially accurate and informative, clearly explaining how this event relates to ongoing changes in the region (with minor exceptions, detailed below).See all the scientists’ annotations in context This is part of a series of reviews of 2017’s most popular climate stories on social media.GUEST COMMENTS: Dan McGrath, Research Scientist, Colorado State University: Well-written article with fabulous graphics for illustrating and explaining rift growth and the 2017 calving event on Larsen C. It correctly highlights future concerns about the potential loss of backstress from key ice rises on the ice shelf (Bawden and Gipps) and the idea that this is a “natural laboratory to study how breakups will occur at other ice shelves.” Further, the article does a nice job explaining how ice shelves provide backstress to upstream glaciers, and why their loss would spell increased ice discharge/sea level rise. However, some statements in the article are misleading, such as: i) “Larsen C, like two smaller ice shelves that collapsed before it, was holding back relatively little land ice….” Larsen C has calved a large iceberg but has NOT collapsed. ii) Rift growth and iceberg calving is not simply connected to atmospheric temperatures (like how surface mass balance processes are, but rather fracture growth is responding to glaciological stresses), hence it is somewhat misleading to make this connection “but scientists believe the ice is still catching up to the higher temperatures.” There are certainly ways that this calving event could be connected to say warmer ocean temperatures that increased basal melting and changed the structure of the ice shelf, but this has not been documented at present. REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Twila Moon Research Scientist, University of Colorado, Boulder: The article does a good job of commenting on both the singular iceberg calving event and the larger picture of ice shelf change on the Antarctic Peninsula. The authors correctly note areas where scientists disagree or do not yet know the answer. Allen Pope Research Associate, National Snow and Ice Data Center, University of Colorado Boulder: The article handles a complex topic well. It would be easy to be alarmist with this subject matter, and while its lede edges that way, the main content of the article is very balanced. It also presents a lot of interesting information in a compelling manner. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time."
https://science.feedback.org/review/new-york-times-accurately-covers-2017-record-low-arctic-winter-sea-ice-extent-henry-fountain/,1.3,"The New York Times, by Henry Fountain, on 2017-03-22.",,"""Arctic’s Winter Sea Ice Drops to Its Lowest Recorded Level""",,,,,"This March 2017 story in the New York Times described the record low extent of Arctic sea ice at its annual maximum. Scientists who reviewed the article found it to be accurate and informative, with only a couple details that could potentially be further clarified.See all the scientists’ annotations in context This is part of a series of reviews of 2017’s most popular climate stories on social media.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Caroline Holmes Polar Climate Scientist, British Antarctic Survey: The article accurately reports on the state of Arctic sea ice at the annual maximum (in March) and its causes, and gives an insightful discussion as to the implications. There is one point which may be misleading: when scientists refer to the Arctic being “ice-free” in summer they specifically mean sea ice extent below a threshold of 1 million square kilometers (386 thousand square miles). This is not made clear in the article and is an important distinction. Nathanael Melia Postdoctoral research fellow, University of Reading: Both of the scientists interviewed are highly respected in their field and are from world leading institutions in polar research. Kelly McCusker Research Associate, Rhodium Group and Climate Impact Lab: This short article correctly explains the state of 2017 maximum Arctic sea ice extent and puts it into historical context. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Featured Annotations: The statements quoted below are from the article; comments and replies are from the reviewers. “Dr. Serreze said that such a situation, which would leave nothing but open ocean in summer until fall freeze-up begins, could occur by 2030, although many scientists say it may not happen for a decade or two after that.” Kelly McCusker Research Associate, Rhodium Group and Climate Impact Lab: 2030 is on the early side of ice-free predictions but definitely not out of the realm of possibility. “Less ice coverage also means that there is more dark ocean to absorb more of the sun’s energy, which leads to more warming and melting in a feedback loop called Arctic amplification.” Kelly McCusker Research Associate, Rhodium Group and Climate Impact Lab: In which Arctic surface air temperatures warm at a faster rate than global average temperature."
https://science.feedback.org/review/conservative-tribune-post-falsely-claims-cancelled-arctic-research-cruise-is-evidence-against-climate-change-benjamin-arie/,-1.5,"Conservative Tribune, by Benjamin Arie, on 2017-06-22.",,"""Global Warming Study Canceled After Humiliating Discovery""",,,,,"In June 2017, an Arctic research cruise had to be postponed because of unusually thick sea ice that had drifted near Newfoundland. Polar field work frequently battles difficult conditions, but several outlets wrote derisive articles (analyzed by Climate Feedback at the time) based on the assumption that such conditions would no longer exist if climate change were really occurring. Scientists who reviewed a post on this topic at Conservative Tribune explained that a number of incorrect assumptions underlie its argument against the validity of climate science. Climate scientists have never predicted that these sea ice conditions will not occur. In fact, the drifting of thick sea ice as far south as Newfoundland could be related to the thinning and loss of sea ice nearer the pole.See all the scientists’ annotations in context This is part of a series of reviews of 2017’s most popular climate stories on social media.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Twila Moon Research Scientist, University of Colorado, Boulder: There is no understanding in this article of the difference between weather (day-to-day or year-to-year variability) and climate (long-term, multi-decade behavior). The author takes advantage of this confusion, and even adds to it, drawing false implications about the scientific method and scientists’ skill. Nathanael Melia Postdoctoral research fellow, University of Reading: There is no science in this article, just some factual statements about an event linked to an agenda driven narrative. The reason un-navigable multi-year ice was found at these locations is because a reduced ice-pack in general allows the multi-year ice to drift from locations where it is historically kept anchored to. June is halfway between the sea ice max and min so these conditions are unsurprising. Polar expeditions are routinely hampered by the seasonal and weekly weather events, it’s part of the reason an ice-breaker was planned to be used in the first place. Kelly McCusker Research Associate, Rhodium Group and Climate Impact Lab: Repeating a version of a debunked argument against climate change science, this biased and misleading political article states that the cancellation of an Arctic research cruise due to increased sea ice at one time and in one region proves climate scientists don’t know anything about climate change over 100 years, which is patently false. The article misrepresents many aspects of our current understanding and is written in a biased manner, using phrases such as “climate change activists [sic] scientists” and “bleeding-heart liberals”. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Featured Annotations: The statements quoted below are from the article; comments and replies are from the reviewers. “Scientists were caught off guard when the true ice conditions were different from their predictions, which took place only months ago…” Kelly McCusker Research Associate, Rhodium Group and Climate Impact Lab: The linked article is not about predictions made for Arctic sea ice. “[…] yet they absolutely know how the climate will behave over the next 100 years.” Kelly McCusker Research Associate, Rhodium Group and Climate Impact Lab: This is a common and misleading argument that has been dispelled many times. Climate projections don’t presume to predict exactly what will be happening and where at any given time, but instead describe the average climate (or the statistics of weather). A decrease in Arctic sea ice extent overall is a well-known feature of climate change, but within that, variability in regional ice concentrations is expected."
https://science.feedback.org/review/iflscience-story-florida-sea-level-rise-somewhat-unclear-generally-correct/,0.7,"IFLScience, by Robin Andrews, on 2017-08-11.",,"""The Sea Level Around Florida Is Rising Six Times Faster Than Average""",,,,,"This story by IFLScience covered an August 2017 study published in Geophysical Research Letters that examined variability of sea level rise rates along the US East Coast. Scientists who reviewed the article found that its summary of the study was largely correct, but was unclear or somewhat misleading in several details (like the relationship between natural variability and the rate of expected future sea level rise).See all the scientists’ annotations in context This is part of a series of reviews of 2017’s most popular climate stories on social media.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Chris Roberts Research Scientist, ECMWF/Met Office: Despite the colloquial tone, the article provides a pretty good summary of the factors responsible for observed sea level variability. The original scientific article is linked from the text and the authors clearly distinguish between the variations associated with climate change and the more rapid and localised change associated with modes of internal variability. However, this distinction between time scales gets lost a bit in the concluding paragraph. The statement that “[Florida] is set to be underwater faster than anyone has previously estimated” is not an accurate representation of the concluding remarks from the original scientific paper, which states that “[the impacts of sea level rise] may be further amplified by short-lived [sea level rise] hot spots”. Andrea Dutton Visiting Associate Professor, University of Wisconsin: [Prof. Dutton was one of the authors of the study described in this article.] While the information in this article is essentially correct, the links lead to loosely related articles published on the same website, rather than articles that directly support the statements made in the article. The explanation of the acceleration of sea level rise in Florida is oversimplified, probably because it is difficult to summarize concisely. The mechanism is actually the combined effect of the El Niño cycle and the North Atlantic Oscillation (NAO). The phrase “faster than average” in the headline is vague: Faster than the average for Florida or the whole world? And over what time period? Benjamin Horton Professor, Earth Observatory of Singapore: The study describes an increase in the rate of sea-level rise in Florida due to ocean-atmosphere processes. The paper illustrates the importance of such variability in assessing the flood risk. But I think the link to anthropogenic climate change is misleading. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time."
https://science.feedback.org/review/new-york-times-news-coverage-2016-global-temperature-data-accurate-summary-justin-gillis/,2,"The New York Times, by Justin Gillis, on 2017-01-18.",,"""Earth Sets a Temperature Record for the Third Straight Year""",,,,,"In January 2017, NASA and NOAA released their data for average global temperature in 2016, which ranked as the warmest year on record. This story in the New York Times described the new record and provided some context for rising temperatures. The scientists who reviewed this article found that it accurately described the data and clearly explained their relationship to climate change.See all the scientists’ annotations in context This is part of a series of reviews of 2017’s most popular climate stories on social media.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Victor Venema Scientist, University of Bonn, Germany: A clear and accurate article on the temperature record in 2016, looking back at the records in 2015 and 2014. The article places them in the proper context of long-term warming, while mentioning the special effects that helped make the year a record. Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: The article was a good summary of the record warmth in 2016. The summary also made a number of useful points that put 2016 into the context of the science of global climate change and the politics of global warming. In particular, the authors highlighted ocean heat accumulation, that global warming is not linear, and also acknowledged that the US has many leaders that are climate skeptics despite continued, record warmth. Patrick Brown Assistant Professor, San Jose State University: Extremely high scientific accuracy for an article intended for a general readership. Appropriate caveats are included without confusing the general story. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Featured Annotations: The statements quoted below are from the article; comments and replies are from the reviewers. “The findings about a record-warm year were also confirmed by the Berkeley Earth surface temperature project, a nonprofit California group set up to provide a temperature analysis independent of governments.That group, however, did not find that three records had been set in a row; in its analysis, 2010 was slightly warmer than 2014.” Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: This is a small, but useful illustration that there is uncertainty in these datasets and their representation of record warmth. “When the heat buildup in the ocean is taken into account, global temperatures are rising relentlessly.” Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: This is an excellent and important point. “The arc of global warming will be variously steep and less steep,’ said Richard Seager, a climate scientist at the Lamont-Doherty Earth Observatory of Columbia University. ‘It never stopped.’” Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: This is another important point to make—there will be periods where the Earth warms less quickly (not every year will be a record year) but the heating of the Earth continues. “The heat extremes were especially pervasive in the Arctic, with temperatures in the fall running 20 to 30 degrees Fahrenheit above normal across large stretches of the Arctic Ocean.” Victor Venema Scientist, University of Bonn, Germany: Where the Arctic ocean freezes the air can get very cold because the ice blocks the heat transport from the relatively warm ocean water. The temperature variability is naturally larger in the Arctic than in the mid-latitudes (USA, Europe). Thus it was very warm in the Arctic. As NASA’s Gavin Schmidt said: “What’s going on in the Arctic is really very impressive; this year was ridiculously off the chart” But 20 to 30 degrees Fahrenheit may not be as exceptional as it sounds to our ears. Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: I agree that sea ice plays an important role, but that doesn’t necessarily mean that the temperature changes are not exceptional. I also agree that on small spatial scales large temperature deviations are not necessarily surprising, but what happened across the Arctic in 2016 was unprecedented according to NOAA. “Since 1880, NOAA’s records show only one other instance when global temperature records were set three years in a row: in 1939, 1940 and 1941.” Victor Venema Scientist, University of Bonn, Germany: The start of the second world war also changed the composition of the fleet making the sea surface temperature observations and with it the measurement methods used changed quickly. Climatologists have made adjustments to account for this problem, but it is well possible that this was incomplete. Uncertainties in this period are larger than in the decades before and after. Thus it could well be that these three records in a row are due to remaining problems. I would not have emphasised it."
https://science.feedback.org/review/futurism-story-great-barrier-reef-compromised-sensational-headline/,-0.5,"Futurism, by Jolene Creighton, June Javelosa, on 2017-04-12.",,"""Scientists Announce That The Great Barrier Reef is Officially “Terminal”""",,,,,"This April 2017 story at Futurism describes a statement released by James Cook University’s ARC Centre of Excellence for Coral Reef Studies on bleaching along Australia’s Great Barrier Reef. Bleaching occurs when corals are exposed to excessively warm water. Scientists who reviewed the article found that most of the information is accurate (except for a couple generalizations), but the headline is not supported by the story. The headline seems to indicate that scientists were quoted as saying the the Great Barrier Reef “is ‘terminal’”, but no source used that word.See all the scientists’ annotations in context This is part of a series of reviews of 2017’s most popular climate stories on social media. REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Terry Hughes Professor, ARC Centre of Excellence for Coral Reef Studies, James Cook University: The content is almost all correct, but the attention-grabbing headline is wrong and isn’t supported by the quotes from two scientists or by the rest of the content. Simon Donner Associate Professor, The University of British Columbia: The short article accurately captures the scientific evidence that repeat mass bleaching events will threaten the Great Barrier Reef, and the message of the ARC official statement. In doing so, however, it is forced into some generalizations including i) describing the Great Barrier Reef as a single entity that can “die” (rather than a complex web of ecosystems that will experience widespread degradation) and ii) stating there have been only four instances of mass bleaching (there have been thousands of events across the world over the past three decades, yet only four years where bleaching occurred in all ocean basins). Mark Eakin Scientist, Coordinator of NOAA’s Coral Reef Watch, National Oceanic and Atmospheric Administration: Much of the story is factually correct. However, the declaration of the reef as “terminal” in the title is a very bad start. What could have been a good story is dragged down by the use of terms like “terminal” without attribution, confuses no time for recovery between back-to-back events with no hope for recovery in the future, and uses a quote saying an expert has “given up” from the perspective of insufficient government action on water quality without providing context for how this relates to a story that is focused on global warming and bleaching. Unfortunately, the facts and quotes don’t support the title. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time."
https://science.feedback.org/review/breitbart-california-fires-misleads-omitting-explanation-climates-influence-joel-pollak/,-1.4,"Breitbart, by Joel Pollak, on 2017-12-09.",,"""Jerry Brown Blames Climate Change for California Fires: ‘The New Normal’""",,,,,"This article in Breitbart criticizes a statement by California Governor Jerry Brown, who said that the recent dangerous fires are “the new normal” for the area. The article correctly lists a number of factors that contribute to wildfires, including weather patterns and the construction of homes in areas at risk of fire. The article represents the contribution of climate change to wildfire trends as unknown, and a matter of debate for climate scientists. Scientists who reviewed the story found this to be misleading. The article fails to explain the ways in which climate change can clearly influence the factors that control wildfires. A number of published studies have found that climate change is an important contributing factor to wildfire behavior in the western United States.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Anthony LeRoy Westerling Associate Professor, University of California, Merced: The article ignores the overwhelming evidence in peer reviewed scientific literature that warmer temperatures and more variable precipitation are exacerbating western US wildfire activity, leading to more large fires, more area burned, changing fire severity, and longer fire seasons. While many other factors interact with climate to influence wildfire, a changing climate is clearly driving an increase in fire risk. The fact that other factors influence wildfire does not imply that climate has no effect on wildfire. Logan Berner Assistant Research Professor, Northern Arizona University: The Breitbart article provides a poorly reasoned and misleading view of how climate change has contributed to recent fires in California and the rest of the western USA. The most informative part of the article is the link that it provides to a piece by Southern California Public Radio, which, unlike the Breitbart article, provides an informative and unbiased look at factors contributing to these recent fires. Stefan Doerr Professor, Swansea University: The article is factually correct with no significant inaccuracies. Indeed no specific wildfire event can be specifically linked to climate change as the main cause. The article correctly states that “climate change could be one of a variety of factors”. It also correctly states that “an important factor […] was that people are building homes in areas that are naturally prone to wildfires, or where naturally dry conditions mean that the kinds of building materials and vegetation [used] are a fire hazard. This, however, is only one of many factors. Climate is not discussed further and it would have been more balanced if the article had also highlighted that climate scientists (i) have shown that the fire season in the southwest USA has lengthened considerably and (ii) generally agree that climate warming increases the probability of the occurrence of large fires in California (as well as many other regions of the world). See for example: Westerling (2016) Increasing western US forest wildfire activity: sensitivity to changes in the timing of spring, Philosophical Transactions of the Royal Society B Doerr and Santin (2016) Global trends in wildfire and its impacts: perceptions versus realities in a changing world,Philosophical Transactions of the Royal Society B Daniel Swain Climate Scientist, University of California, Los Angeles: This article mixes several true statements with a much larger number of demonstrably false assertions, yielding a very misleading piece overall. While it is true that potential links between climate change and the strength/magnitude of Santa Ana winds themselves remain uncertain, links between warming temperatures and drying vegetation (and therefore wildfire risk) have been extensively demonstrated. Autumn 2017 was the warmest and second driest such period on record in coastal Southern California—which has yielded explosive fire conditions that both the National Weather Service and state/local fire agencies have confirmed are the most severe on record for this time of year. Recent studies suggest that further warming and vegetation drying due to climate change will likely increase the amount of area burned by wildfire in southwestern California, even absent changes in the strength of Santa Ana winds. An even clearer link already exists between warming temperatures and increasing wildfire risk more broadly across the American West. Ben Poulter Research Scientist, NASA: One only has to read the links in the article to understand that climate change is the underlying driver of the unusually intense 2017 winter fires that are impacting both the people and places of Southern California. Wildfires result from complex interactions between ignitions, fuel availability, and weather, and after accounting for the role of people and management, climate change has been shown to affect and exacerbate all three. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time."
https://science.feedback.org/review/daily-caller-uncritically-reports-misleading-satellite-temperature-study-michael-bastasch/,-0.6,"The Daily Caller, by Michael Bastasch, on 2017-11-29.",,"""STUDY: Satellites Show No Acceleration In Global Warming For 23 Years""",,,,,"This article in The Daily Caller describes a recent study published on the University of Alabama at Huntsville satellite temperature dataset. The study claims that, after removing the cooling influence of two large volcanic eruptions in 1982 and 1991, the rate of warming is slower than simulated by climate models. While The Daily Caller story accurately describes the study, it fails to include comments from other scientists in the field or to provide necessary context for readers, as the scientists who reviewed the story explained. For example, the study fails to account for more recent volcanic activity, and does not support its conclusion that climate models are overly sensitive to CO2. In addition, the story’s headline emphasizes that the study shows “no acceleration in global warming for 23 years” and this is presented as a challenge to model simulations. This is misleading, as no acceleration of the warming rate is expected to be seen in such a short timeframe.See all the scientists’ annotations in context This is part of a series of reviews of 2017’s most popular climate stories on social media.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Alexis Berg Research Associate, Harvard University: This article reports on a new study by Christy and McNider that, in my view, contains little new regarding atmospheric temperature trends and seems to simply assert that model-observation discrepancies are due to model errors. Also, it seems the absence of accelerating warming trends is meant to go against prevailing climate science, but I find that to be a strawman argument. In that sense the article is misleading—however, to its credit, it does report on other published results that contradict this recent study, but it fails to provide further context or to make any effort to compare/reconcile the validity of these different studies. Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: The article includes many points made in the original study, but leaves out or de-emphasizes issues that are important to the interpretation of the results. Other factors contribute to model-observational differences in atmospheric warming, but the presentation makes it seem like the difference is largely a result of climate model sensitivity errors. Francois-Marie Breon Senior Scientist, Commissariat à l'Energie Atomique: The general public article provides a fairly accurate summary of the John Christy paper. It may lack some information about the general context, and could have emphasized some of the uncertainties in the satellite data and the fact that the temperature analysis refers to rather high atmospheric levels rather than the low levels where humans live. I also note that, a few years back, the skeptics said that the warming had “stopped” whereas they now say that there is “no acceleration”. This is a nice progress towards the truth. Victor Venema Scientist, University of Bonn, Germany: The article contains some inaccuracies, but the main problem is that it depends on only one source, which the article admits is “contentious”. The authors have a long tradition of overconfidence in their data, their dataset has often needed large adjustments and has a large structural uncertainty and the study was published in a low-level journal. Even without these red flags, it is a good tradition in science reporting to ask experts in the field for their assessment of the study and to provide context, which is completely missing. Bad journalism. Carl Mears Senior Research Scientist, Remote Sensing Systems (RSS): The article does an adequate job of describing the Christy and McNider paper, but leaves out discussion of several assumptions, caveats, and alternative explanations in the original paper. In particular, both the article and the original paper ignore the contribution of small but important volcanic eruptions in the 21st century that have been shown to exhibit a cooling influence on tropospheric temperatures after 2000. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Featured Annotations: The statements quoted below are from the article; comments and replies are from the reviewers. “STUDY: Satellites Show No Acceleration In Global Warming For 23 Years” Carl Mears Senior Research Scientist, Remote Sensing Systems (RSS): The article leaves out several assumptions, caveats, and alternative explanations, some of which are described in the original paper. 1. Both the article and the original paper ignore the effects of smaller but important eruptions in the 21st century that cause a cooling effects that is not included in the model forcings. These have been shown to have a significant effect on the post-2000 trends1,2. The original paper brushes these later eruptions aside without discussing why their results might differ from the earlier Santer et al. results. By then fitting to a model that includes only the earlier eruptions, a decrease in overall warming is guaranteed in their analysis. 2. In the original paper, the authors rightly discuss the possibility that more heat has been sequestered into the ocean in “real life” than is simulated by the models. This is likely the case because of the increase in oceanic windspeed (and thus ocean mixing) in the tropics over the last few decades that is not generally present in the model results. In the article, only the sensitivity to carbon dioxide is discussed, supported by a quote from Dr. Christy. Blaming any model/measurement discrepancy on one possible cause, CO2 sensitivity, that has a large effect on the multidecadal time scale, while ignoring other possible causes, such as smaller volcanoes or internal variability) that may average out on the long term is “cherry picking”. This is done in the article, and to a smaller degree in the original paper. 3. The original paper make an admittedly bold assumption (as noted in the paper) that internal variability can be ignored while calculating transient sensitivity to increasing carbon dioxide. The leads to less uncertainty in the derived transient sensitivity results than can likely be justified. No discussion of this assumption appears in the article. 4. Both the article and the original paper fail to place the new results in context of other diagnostics of global warming. These include surface temperature (which is likely more precisely measured and certainly has a longer measurement record) and ocean heat content (which is likely where at least a portion of the missing heat has gone). 1- Santer et al (2014) Volcanic contribution to decadal changes in tropospheric temperature, Nature Geoscience 2- Santer et al (2015) Observed multivariable signals of late 20th and early 21st century volcanic activity, Geophysical Research Letters Victor Venema Scientist, University of Bonn, Germany: The study was actually about satellite estimates of the upper air temperature for the much longer period January 1979 – June 2017. It is possible to see an acceleration of the warming over the last century. In the graph below showing three well-known temperature change estimates based on the surface air temperature observations the warming is clearly smaller around 1900 than it is around 2000. In other words the warming has accelerated. Source: IPCC For a period of a few decades one does not expect to be able to see an acceleration, especially in the even more noisy upper air temperature estimates. “Global warming has not accelerated temperature rise in the bulk atmosphere in more than two decades” Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: This is not a particularly new result. It has long been known that warming has not accelerated in the observations in the last decade. Although this is well-documented in the surface record, it has also been noted in the satellite record as well. Foster and Rahmstorf (2011) Global temperature evolution 1979 – 2010, Environmental Research Letters Gleisner et al (2016) Recent global warming hiatus dominated by low-latitude temperature trends in surface and troposphere data, Geophysical Research Letters Medhaug et al (2017) Reconciling controversies about the ‘global warming hiatus’, Nature Santer et al (2017) Causes of differences in model and satellite tropospheric warming rates, Nature Geoscience Alexis Berg Research Associate, Harvard University: This is not a new finding. As the article itself mentions, this has been shown in previous studies. Also, this (and the title) makes it sound as though the expectation was too find accelerating trends in atmospheric temperatures (and thus that the “alarmists” are wrong), but I don’t believe this is the case over a relatively short time-span such as the one in this study (30-40 yrs). “We indicated 23 years ago — in our 1994 Nature article — that climate models had the atmosphere’s sensitivity to CO2 much too high,” Christy said in a statement. “This recent paper bolsters that conclusion.” Victor Venema Scientist, University of Bonn, Germany: This 23 years is likely where the mistake in the title comes from. Although the data in this Christy and McNider article from 1994 turned out to have major errors, for example not taking into account that the satellites drift, which caused the underestimation of the warming, it started the tradition of Christy and McNider being overconfident about the reliability of their data (“perhaps the best measurements of the Earth’s air temperature in terms of its global coverage and precision.”). And the tradition of immediately blaming climate models, ignoring many other independent lines of evidence on warming and climate sensitivity, when there can be many other reasons for the difference between their data and climate models. In this 1994 paper, Christy and McNider’s data showed almost no warming. In that respect one could say that 23 years of removing errors from the satellite temperature data has accelerated upper air warming. Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: One curious aspect of this statement is that the trend in over the first 15 years (1979 – 1993) is seemingly taken from a much older version of the UAH satellite lower tropospheric temperature dataset. This dataset has since been improved as inhomogeneities have been discovered and corrected, including satellite orbital decay, an error in the diurnal correction, and a miscalibration of the NOAA-9 satellite. Each of these issues would have spuriously reduced the trend in the UAH dataset—presumably if this specific result were revisited models and satellites would agree much better over 1979 – 1993. Wentz and Schabel (1998) Effects of orbital decay on satellite-derived lower tropospheric temperature trends, Nature Mears and Wentz (2005) The Effect of Diurnal Correction on Satellite-Derived Lower Tropospheric Temperature, Science Po-Chedley and Fu (2012) A Bias in the Midtropospheric Channel Warm Target Factor on the NOAA-9 Microwave Sounding Unit, Journal of Atmospheric and Oceanic Technology Spencer et al (2017) UAH Version 6 Global Satellite Temperature Products: Methodology and Results, Asia-Pacific Journal of Atmospheric Sciences “showed virtually no change in the rate of warming since the early 1990s.” Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: The periods compared by the authors are somewhat arbitrary (1979 – 1993 and 1979 – 2017) since they are comparing their new result with their older study (in 1994). This makes it a little difficult to compare with other studies on this topic, though, again, this result is not necessarily surprising. “Models are too sensitive to increases in carbon dioxide concentrations in the atmosphere, he said.” Victor Venema Scientist, University of Bonn, Germany: He said without providing evidence for this claim. There are many independent lines of evidence on the sensitivity of the global temperature to changes in carbon dioxide concentrations. From basic physics, a large number of different period with climatic changes in the deep past and the cooling observed for volcano eruptions. Source: IPCC Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: While others have documented differences in the rate of warming between models and observations, this study is different in that the authors suggest that these differences are because models are too sensitive to increases in atmospheric carbon dioxide. Several studies disagree with this assessment in both the surface and atmospheric record. Other factors contribute to this apparent discrepancy (and some are noted in the original study). These include the potential for observational biases, errors in external forcing prescribed to the models, and real world multidecadal climate variability. So the attribution of model-observational differences predominantly to models is not supported. Richardson et al (2016) Reconciled climate response estimates from climate models and the energy budget of Earth, Nature Climate Change Santer et al (2017): Causes of differences in model and satellite tropospheric warming rates, Nature Geoscience Alexis Berg Research Associate, Harvard University: This claim is not substantiated by the study. There are several hypotheses to explain why model trends and observations do not agree—internal variability, errors in forcings, model error. Mr. Christy favors the last one, but, as far as I can tell, his study makes no effort to analyse the plausibility of different causes (in fact, it seems they explicitly assume that internal variability and forcing error are not a cause). The other study cited in this piece, Ben Santer’s paper, goes much further and actually tries to evaluate the plausibility of each hypothesis -and, as the article mentions, comes to different conclusions. Note also that surface warming in models is in agreement with observations. The question is then why atmospheric warming seems to not be—the models appear to run a little warm there over the last two decades. “climate models predict too much warming in the troposphere” Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: One issue with such comparisons is that the observational record of atmospheric warming is quite uncertain as evidenced by the large trend differences between different groups that create satellite temperature datasets and even between versions of each group’s datasets. Mears et al (2011) Assessing the uncertainty in estimates of atmospheric temperature changes from MSU and AMSU using a Monte-Carlo estimation technique, Journal of Geophysical Research “While many scientists have acknowledged the mismatch between model predictions and actual temperature observations, few have really challenged the validity of the models themselves.” Alexis Berg Research Associate, Harvard University: A better way to put it would be that, given the data, few have come to the conclusion at this point that models are fundamentally flawed. “A recent study led by Lawrence Livermore National Laboratory climate scientist Ben Santer found that while the models ran hot, the ‘overestimation’ was ‘partly due to systematic deficiencies in some of the post-2000 external forcings used in the model simulations.’” Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: This is right—models have the wrong “external forcings” (such as volcanic forcing), which is likely an important factor in model-observational differences. It is also possible that errors in removing volcanic forcing and natural variability could also affect model-observational comparisons. Solomon et al (2011) The Persistently Variable “Background” Stratospheric Aerosol Layer and Global Climate Change, Science Santer et al (2014) Volcanic contribution to decadal changes in tropospheric temperature, Nature Geoscience “While volcanic eruptions are natural events, it was the timing of these that had such a noticeable effect on the trend” Victor Venema Scientist, University of Bonn, Germany: That is one of the disadvantages of using such a short dataset. For the more reliable station observations of surface air temperature observations go back in the 19th century making the contribution of (individual) volcanoes a lot smaller. Source: Global Warming Index “removing the climate effects of volcanic eruptions early on in the satellite temperature record” Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: Note that although there is nothing wrong with attempting to remove these effects from the temperature time series, it can be quite uncertain and subject to methodology, especially over short timescales. As noted in the research paper, multidecadal variability may also effect the results. Several studies have noted that multidecadal variations in the rate of ocean heat uptake have affected observed warming rates. Santer et al (2001) Accounting for the effects of volcanoes and ENSO in comparisons of modeled and observed temperature trends, Journal of Geophysical Research Chen and Tung (2014) Varying planetary heat sink led to global-warming slowdown and acceleration, Science “‘Those eruptions happened relatively early in our study period, which pushed down temperatures in the first part of the dataset, which caused the overall record to show an exaggerated warming trend,’ Christy said. ‘While volcanic eruptions are natural events, it was the timing of these that had such a noticeable effect on the trend. If the same eruptions had happened near the more recent end of the dataset, they could have pushed the overall trend into negative numbers, or a long-term cooling,’ Christy said.” Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: This study does not include the effect of smaller volcanoes late in the record that would have reduced real-world warming. Since these volcanoes were not included in model simulations, the model simulations would also have too much warming, since they did not include accurate representation of the effect of volcanic activity. This would have increased the model-observational discrepancy. Santer et al (2014) Observed multivariable signals of late 20th and early 21st century volcanic activity, Geophysical Research Letters “climate models need to be retooled to better reflect conditions in the actual climate” Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: It’s important to note that climate scientists do work on both understanding model-observational discrepancies and improving models. Another aspect to consider is that observations also have biases that can affect such comparisons. “policies based on previous climate model output and predictions might need to be reconsidered” Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: This study alone does not support this kind of broad statement, especially given that there are already several studies that disagree with the authors results."
https://science.feedback.org/review/prof-john-christy-incorrectly-claims-to-show-climate-models-are-too-sensitive-to-carbon-dioxide/,Incorrect,"The Daily Caller, John Christy, 2017-11-29",the real atmosphere is less sensitive to CO2 than what has been forecast by climate models,,"Inadequate support: Prof. Christy's study does not provide the evidence to support this conclusion, which contradicts many other published studies.","There are many reasons why a climate model projection may not perfectly match observations of some aspect of Earth's climate over a given time period, including short-term variability, differences between real-world and simulated emissions, and even measurement errors. Prof. Christy asserts that models are too sensitive to CO2 but provides no evidence to support that claim. Other research has concluded that Prof. Christy's assertion is incorrect.","From our observations we calculated that value as 1.1 C (almost 2° Fahrenheit), while climate models estimate that value as 2.3 C (about 4.1° F). Again, this indicates the real atmosphere is less sensitive to CO2 than what has been forecast by climate models.",,"Victor Venema Scientist, University of Bonn, Germany: He said without providing evidence for this claim. There are many independent lines of evidence on the sensitivity of the global temperature to changes in carbon dioxide concentrations. From basic physics, a large number of different period with climatic changes in the deep past and the cooling observed for volcano eruptions. Source: IPCC Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: While others have documented differences in the rate of warming between models and observations, this study is different in that the authors suggest that these differences are because models are too sensitive to increases in atmospheric carbon dioxide. Several studies disagree with this assessment in both the surface and atmospheric record. Other factors contribute to this apparent discrepancy (and some are noted in the original study). These include the potential for observational biases, errors in external forcing prescribed to the models, and real world multidecadal climate variability. So the attribution of model-observational differences predominantly to models is not supported. Richardson et al (2016) Reconciled climate response estimates from climate models and the energy budget of Earth, Nature Climate Change Santer et al (2017): Causes of differences in model and satellite tropospheric warming rates, Nature Geoscience Alexis Berg Research Associate, Harvard University: This claim is not substantiated by the study. There are several hypotheses to explain why model trends and observations do not agree—internal variability, errors in forcings, model error. Mr. Christy favors the last one, but, as far as I can tell, his study makes no effort to analyse the plausibility of different causes (in fact, it seems they explicitly assume that internal variability and forcing error are not a cause). The other study cited in this piece, Ben Santer’s paper*, goes much further and actually tries to evaluate the plausibility of each hypothesis—and, as the article mentions, comes to different conclusions. Note also that surface warming in models is in agreement with observations. The question is then why atmospheric warming seems to not be—the models appear to run a little warm there over the last two decades. Santer et al (2017): Causes of differences in model and satellite tropospheric warming rates, Nature Geoscience Reto Knutti Professor, ETH Zürich: [This comment is taken from an evaluation of a similar statement.] Statements that climate models overestimate the warming in response to CO2are incorrect; they are based on either too short time periods that are dominated by natural variability, by the comparison of models with datasets that do not have global coverage, by comparing to models that were run many years ago with emissions and forcings that differed from what actually happened, by the use of oversimplified energy balance models1, or a combination of these. Recent studies have shown that once the changes in climate feedbacks over time2, datasets with full coverage3,and all forcings are considered, the agreement between predicted and observed warming is excellent, even over the recent hiatus period4. It is remarkable that even projections made decades ago with climate models that were much simpler (and were running on computers that were likely slower than a mobile phone today) were quite accurate5,6,7. 1- Knutti and Rugenstein (2015) Feedbacks, climate sensitivity and the limits of linear models, Philosophical Transactions of the Royal Society A 2- Armour (2017) Energy budget constraints on climate sensitivity in light of inconstant climate feedbacks, Nature Climate Change 3- Richardson et al (2016) Reconciled climate response estimates from climate models and the energy budget of Earth, Nature Climate Change 4- Medhaug et al (2017) Reconciling controversies about the ‘global warming hiatus’, Nature 5- Stouffer and Manabe (2017) Assessing temperature pattern projections made in 1989, Nature Climate Change 6- Fischer and Knutti (2016) Observed heavy precipitation increase confirms theory and early models, Nature Climate Change 7- Allen et al (2013) Test of a decadal climate forecast, Nature Geoscience Katrin Meissner Professor, University of New South Wales: [This comment is taken from an evaluation of a similar statement.] Climate Sensitivity has been assessed by the community based on recent observations and proxy data from past climates. Climate models fall within this range of sensitivity. Some recent publications point to an increase in sensitivity with warmer temperatures*. Paleosens Project Members (2013) Making sense of palaeoclimate sensitivity, Nature Meraner et al (2013) Robust increase in equilibrium climate sensitivity under global warming,Geophysical Research Letters Zeebe (2013) Time-dependent climate sensitivity and the legacy of anthropogenic greenhouse gas emissions,Proceedings of the National Academy of Sciences"
https://science.feedback.org/review/antarctica-doomsday-glaciers-could-flood-coastal-cities-grist-eric-holthaus/,0.8,"Grist, by Eric Holthaus, on 2017-11-21.",,"""Ice Apocalypse""",,,,,"This article at Grist by Eric Holthaus examines the risk of greater sea level rise caused by a more rapid loss of glacial ice. It focuses on a process recently added to one ice sheet model (ice cliff instability), which greatly accelerated the simulated loss of Antarctic ice in a warming climate, suggesting that we could see more sea level rise by 2100 than previously projected. Scientists who reviewed the article found that while it accurately described recent research on these processes, it should have provided more accurate context on the timescale of these sea level rise scenarios and the scientific uncertainty about how likely these scenarios are to come to pass.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Twila Moon Research Scientist, University of Colorado, Boulder: The major failure of the article is that it incorrectly presents the scientifically published timeline for worst case sea level rise. This is unfortunate, because the overall information in the article about marine ice-cliff instability potentially causing sea levels to rise much sooner than previously thought is correct and important to communicate, and the quoted scientists’ statements are accurate. Henning Åkesson Postdoctoral researcher, Stockholm University and Bolin Centre for Climate Research: The article gives important insight into recent research progress on West Antarctica, the prospects of rapid sea-level rise, and its implications. What is presented is accurate and fairly balanced—though there is by no means a consensus within the glaciological community to whether ice-cliff failure is likely to occur in the future, the possibility is troublesome enough. Alexander Robel Assistant Professor, Georgia Tech: This article does a good job of summarizing some recent work on the potential for a marine ice cliff instability in Antarctica, an idea which is being actively discussed within our community to determine whether it is likely to occur in the future. Since we still do not completely understand all the processes that contribute to ice sheet evolution (including ice cliff breakup), it is difficult to distinguish which specific scenarios are “likely” or “unlikely” beyond saying that: sea level is rising, and it will continue to rise for at least hundreds of years in the future at a rate that is, in part, modulated by human choices. Mauri Pelto Professor of Environmental Science, Associate Dean, Nichols College: The article has a bias, emphasizing the high end scenarios of ice sheet behavior, avoiding scrutiny of model assumptions. The concept of marine ice cliff instability and how unusual it is as a mechanism today on the vast coastline of Antarctica or Greenland is ignored. Jan Lenaerts Assistant Professor, University of Colorado, Boulder: Eric Holthaus provides a dire, but mostly correct, assessment of the processes driving—and risks associated with—a potential rapid disintegration of the West Antarctic ice sheet. The article would be improved in places by providing more context and/or references. Allen Pope Research Associate, National Snow and Ice Data Center, University of Colorado Boulder: This piece does a good job including a range of true experts talking about the frontiers of our understanding of the Antarctic Ice Sheet. While not out of the range of possibility, the future painted (and the associated pessimist/alarmist tendencies) in the article might be a little higher than the research can definitively back up right now. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Annotations: The statements quoted below are from the article; comments and replies are from the reviewers. “finding out how fast these glaciers will collapse is one of the most important scientific questions in the world today” Twila Moon Research Scientist, University of Colorado, Boulder: There are many important science questions, but it is true that understanding the rate of ice loss at Pine Island and Thwaites Glaciers is very important for understanding how quickly future sea level rise will happen. Understanding Thwaites is arguably more important than Pine Island, though they are part of a connect region of ice. A recent peer-reviewed science article that takes a closer look at the question and explains the importance of understanding changes is Scambos et al, 2017*. Scambos et al (2017)How much, how fast?: A science review and outlook for research on the instability of Antarctica’s Thwaites Glacier in the 21st century, Global and Planetary Change “There’s growing evidence that the Pine Island Bay glaciers collapsed rapidly back then, flooding the world’s coastlines — partially the result of something called ‘marine ice-cliff instability.’” Twila Moon Research Scientist, University of Colorado, Boulder: Following earlier theory work by Jeremy Bassis and others, the marine ice-cliff instability term was introduced (as far as I’m aware) in 2015 in Pollard et al, 20151. The two lead authors then continued to investigate the mechanism using computer simulations, publishing a paper in Nature in 20162. The idea of the marine ice-cliff instability is still fairly controversial amongst glaciologists (NOT to be confused with the marine ice sheet instability, which is not controversial and is another reason that West Antarctica is vulnerable to rapid ice loss). A recent paper in Nature3 suggests that there is observational evidence from ancient iceberg tracks, but not all glaciologists are convinced that this new data fully supports the marine ice-cliff instability. Whether the marine ice-cliff instability is something that is likely to occur in Antarctica is still debated amongst scientists. 1- Pollard et al (2015)Potential Antarctic Ice Sheet retreat driven by hydrofracturing and ice cliff failure, Earth and Planetary Science Letters 2- DeConto and Pollard (2016)Contribution of Antarctica to past and future sea-level rise, Nature 3-Wise et al (2017)Evidence of marine ice-cliff instability in Pine Island Bay from iceberg-keel plough marks, Nature Henning Åkesson Postdoctoral researcher, Stockholm University and Bolin Centre for Climate Research: I largely agree. Much of the theoretical framework was established by Bassis and Walker (2012)*. They predicted a “maximum cliff height that increases with water depth”. Bassis and Walker (2012)Upper and lower limits on the stability of calving glaciers from the yield strength envelope of ice, Philosophical Transactions of the Royal Society A “Before human burning of fossil fuels triggered global warming, the continent’s ice was in relative balance” Twila Moon Research Scientist, University of Colorado, Boulder: Yes. Research suggests that the ice sheet was likely near balance up until close to the turn of the 21st century. “All this could play out in a mere 20 to 50 years — much too quickly for humanity to adapt.” Twila Moon Research Scientist, University of Colorado, Boulder: This is a statement that is difficult to justify without a reference to scientific evidence. The current knowledge of time scales involved with rapid ice sheet loss is poor (i.e., solely based on ice sheet models that are crude)—that’s the primary reason why the “How Much How Fast” US-UK program was established. “With marine ice cliff instability, sea-level rise for the next century is potentially much larger than we thought it might be five or 10 years ago” Twila Moon Research Scientist, University of Colorado, Boulder: That is true. For a recent look at how our ideas of likely future sea level rise have changed, this is a useful short piece from Science: How high will the seas rise? If marine ice-cliff instability is confirmed as a likely or expected method of Antarctic ice loss then ice loss can occur more quickly than previously thought. Richard Alley Professor, PennState University: The basic idea is I believe correct—if Thwaites Glacier in West Antarctica in the future begins to behave the way Greenland’s ice sheet is now behaving at Jakobshavn, Helheim and some other outlets, the resulting future sea level rise is likely to be notably higher and faster than currently projected by the IPCC. Iceberg calving from non-floating (tidewater) fronts is a widespread and well-known process (passengers on cruise ships to Alaska have been observing it routinely, for example), and the rate of calving is generally accepted to increase in deeper water and to be favored by reduced friction from the sides, for robust physical reasons. The Greenland outlets are in ~1 km deep fjords that are only a few km wide; furthermore, retreat out of these relatively narrow and short fjords would not greatly raise global sea level (most of Greenland’s ice rests on bedrock that is near or above sea level). Retreat of Thwaites Glacier could reach much deeper water with a much wider calving front, and beyond some threshold of retreat is generally modeled as triggering the full deglaciation of the marine basins with ~3 meters of globally averaged sea-level rise, because so much of West Antarctica’s ice rests on interconnected deep beds. The DeConto-Pollard numbers (and earlier, the Pollard-DeConto-Alley numbers, so note that I was involved with earlier parts of this research) assumed that if triggered, the retreat in West Antarctica would not be as fast as the fastest rates already observed in Greenland (a maximum retreat rate was set in the model); the notably greater sea-level contribution of West Antarctica in the new modeling arises from the much broader calving front that would be activated. But, the greater depth and width of West Antarctica’s deep marine basins than in Greenland could produce much faster calving than in Greenland. Hence, the DeConto-Pollard simulations are not a worst-case scenario. The uncertainties remain very large, especially regarding the amount of warming to that threshold. But, because tidewater calving is such a widespread process, it is highly likely that warming beyond some threshold will cause tidewater processes to occur in West Antarctica, consistent with the paleo-observations in deglaciated marine areas off Pine Island Bay. Current physical understanding then leads to the expectation of quite rapid sea-level rise. Much work remains to be done to narrow the uncertainties, including analyses of the “mélange” of broken-up icebergs mentioned by Ted Scambos—but note that such a mélange is present in the narrow fjord of Jakobshavn, providing a backstress that has still allowed the rapid retreat observed there. I believe DeConto and Pollard have taken a well-justified path in estimating the warming threshold, but much additional work can be done. Many other models that project smaller future sea-level rise from West Antarctica also lack the transition to tidewater calving. If warming becomes large enough to trigger tidewater processes in West Antarctica (or East Antarctica), then models lacking those processes are not useful for providing either most-likely or worst-case scenarios for sea-level rise. “‘Antarctic model raises prospect of unstoppable ice collapse,’ read the headline in the scientific journal Nature, a publication not known for hyperbole.” Jan Lenaerts Assistant Professor, University of Colorado, Boulder: Good to mention that the same journal published another set of Antarctic sea level rise projections one year before (2015) that are far less dire*. Ritz et al (2015)Potential sea-level rise from Antarctic ice-sheet instability constrained by observations, Nature “Instead of a three-foot increase in ocean levels by the end of the century, six feet was more likely, according to DeConto and Pollard’s findings. But if carbon emissions continue to track on something resembling a worst-case scenario, the full 11 feet of ice locked in West Antarctica might be freed up, their study showed.” Twila Moon Research Scientist, University of Colorado, Boulder: This timeline represented here is not an accurate representation of the paper’s findings. Figure 4(below) in the paper is the most helpful. It shows that 11 feet by 2100 in not expected in the tested worst case. However, the paper also addresses sea level rise past 2100. Under the Intergovernmental Panel on Climate Change Representative Concentration Pathway (RCP) 8.5 (the worst case they discussed), the paper suggests sea level rise from Antarctica alone could be 15.65 +/- 2 m by 2500. These numbers are shown in Figure 5 of the Pollard and DeConto Nature paper. A still deeply disturbing finding. Alexander Robel Assistant Professor, Georgia Tech: The study referenced1 finds that, assuming some different possible scenarios for the speed of ice sheet processes and the IPCC’s highest emissions scenario (RCP 8.5), Antarctica alone can contribute anywhere from 0.5 to 4.5 feet (Figure 5b and d, below) of sea level rise. The DeConto & Pollard study1 does not include the potential for sea level rise from thermal expansion of sea water, melting of mountain glaciers or the Greenland Ice Sheet in it’s projections, but if these are included, the total sea level rise projected for 2100 may be something like 6 feet. If this is the calculation implicit in this statement that “…six feet was more likely, according to DeConto and Pollard’s findings”, than it is perhaps a bit misleading, since DeConto & Pollard is only focused on the contribution from the Antarctic Ice Sheet. As DeConto & Pollard say in their study: “…the rates of ice loss simulated here should not be viewed as actual predictions, but rather as possible envelopes of behaviour”. Determining the “likely” amount of sea level rise in the future is a prediction that is strongly dependent on the assumptions about how ice sheet behave and on what time scales. Based on just DeConto & Pollard’s studies, and the assumptions inherent in their model, one can conclude that it is likely that sea level will rise by more than 11 feet, just from Antarctic melting, over the next several centuries, if humans do not significantly reduce emissions of greenhouse gases (see Figure 5 and S7 of DeConto & Pollard 2016). What the glaciological community as a whole considers “likely” depends on which processes we think are likely to be important contributors of ice sheet collapse, which is a matter that is actively under debate. Since the DeConto & Pollard study is relatively new, there is still an ongoing discussion about how likely it is that the Marine Ice Cliff Instability will actually occur and at what rate will it causes ice to be lost from individual glaciers. Though the article as a whole covers some parts of this debate, these individual statements about likelihood do not necessarily reflect a community consensus. DeConto and Pollard (2016)Contribution of Antarctica to past and future sea-level rise, Nature “it now seems like three feet is possible only under the rosiest of scenarios” Henning Åkesson Postdoctoral researcher, Stockholm University and Bolin Centre for Climate Research: Given DeConto and Pollard’s results, yes, though their model is one out of several models being actively developed to predict future sea-level rise. Alexander Robel Assistant Professor, Georgia Tech: Including the contribution from thermal expansion of seawater, mountain glaciers, and Greenland, three feet is probably a good estimate for the lower bound on the total sea level rise that can be expected from current and past climate change (many studies ask this question, but Pfeffer, 2008* is an oft-cited example). The key phrase here is total sea level rise, which may unfold in the next century or over the next several millennia as ice sheets continue to respond to past climate change for many hundreds to thousands of years. If this phrase refers to three feet of sea level rise from Antarctica by 2100, then it does not accurately represent the findings of DeConto & Pollard (see RCP 2.6 in Figure 5 of that study, above). Pfeffer et al (2008)Kinematic Constraints on Glacier Contributions to 21st-Century Sea-Level Rise, Science “the world’s most vulnerable megacities, like Shanghai, Mumbai, and Ho Chi Minh City, could be wiped off the map” Henning Åkesson Postdoctoral researcher, Stockholm University and Bolin Centre for Climate Research: I think this statement is too dramatic. While rising seas is a very serious challenge for populous coastlines worldwide, we have the possibility to adapt. But of course the ability to adapt will depend on how fast these changes pan out. “Pollard and DeConto are the first to admit that their model is still crude, but its results have pushed the entire scientific community into emergency mode.” Twila Moon Research Scientist, University of Colorado, Boulder: Many people in the glaciology community are working to improve computer models of ice sheet change. I actually think that many scientists already felt that humans should be in “emergency mode”. For reference, consider the “World Scientists’ Warning to Humanity”, first written in 1992 and reprised this year. But I agree that the possibility of marine ice-cliff instability raised another alarm bell. “Scientists used to think that ice sheets could take millennia to respond to changing climates” Twila Moon Research Scientist, University of Colorado, Boulder: This was a common perspective before the era of satellite data that showed rapid changes on ice sheets. “In a new study out last month in the journal Nature, a team of scientists from Cambridge and Sweden point to evidence from thousands of scratches left by ancient icebergs on the ocean floor, indicating that Pine Island’s glaciers shattered in a relatively short amount of time at the end of the last ice age.” Twila Moon Research Scientist, University of Colorado, Boulder: As noted earlier, I think there is still some disagreement on whether these are conclusive results. “But there’s reason to think Thwaites and Pine Island could go even faster than Jakobshavn.” Henning Åkesson Postdoctoral researcher, Stockholm University and Bolin Centre for Climate Research: I don’t think we know this yet, and the author doesn’t really back up this claim. The topography beneath Jakobshavn extends to great depths (more than 1 km) for several tens of kilometres upstream of the current calving front (see this recent study by An et al, 2017*). This type of geometry may allow for rapid retreat without any extra push from a warming climate. Thwaites and Pine Island are completely different beasts—the sheer scale and the sea-level equivalent they contain is what’s troublesome with these two. An et al (2017)Bed elevation of Jakobshavn Isbræ, West Greenland, from high-resolution airborne gravity and other data, Geophysical Research Letters Alexander Robel Assistant Professor, Georgia Tech: Yes, there are reasons to think Thwaites and Pine Island could collapse quickly, the most basic among them being that these glaciers are wider and potentially more slippery at the bed than Jakobshavn. “But recent examples from other regions, like the rapidly collapsing Larsen B ice shelf on the Antarctic Peninsula, show that once ice shelves break apart as a result of warming, their parent glaciers start to flow faster toward the sea, an effect that can weaken the stability of ice further inland, too.” Jan Lenaerts Assistant Professor, University of Colorado, Boulder: Regarding ice shelf stability, it is important to acknowledge (which the author didn’t do here) there are different processes at work on the Antarctic Peninsula, where the Larsen ice shelves reside(d), than on the Amundsen coast (Pine Island and Thwaites ice shelves). The Larsen A and B ice shelves were very thin, and have disintegrated from percolating surface meltwater (hydrofracturing) creating vertical cracks in the ice shelf. Larsen C is thicker and larger, but is also characterised by a relatively warm climate (many melt episodes in summer) and low snowfall (which makes it vulnerable to atmospheric warming). The ice shelves that buttress the Pine Island and Thwaites glaciers are much thicker, annual snowfall rates are very large, and surface melt rates are substantially lower than on the (former) Larsen ice shelves (3-5 times lower). Therefore, it is highly unlikely that surface-based ice shelf instability will occur within the next few decades—instead, these ice shelves would likely thin through contact with warmer ocean waters. “‘If you remove the ice shelf, there’s a potential that not just ice-cliff instabilities will start occurring, but a process called marine ice-sheet instabilities,’ says Matthew Wise, a polar scientist at the University of Cambridge. This signals the possible rapid destabilization of the entire West Antarctic ice sheet in this century.” Twila Moon Research Scientist, University of Colorado, Boulder: Multiple studies have indicated that the marine ice sheet instability is likely already underway in the Pine Island region1,2. There has been no evidence to suggest that the loss of ice from this region will stop. However, that the loss of ice from marine ice sheet instability is underway does NOT mean that the entire West Antarctic Ice Sheet will destabilize this century. There is no evidence for the ice loss to occur that quickly. 1- Joughin et al (2014) Marine Ice Sheet Collapse Potentially Under Way for the Thwaites Glacier Basin, West Antarctica, Science 2- Rignot et al (2014) Widespread, rapid grounding line retreat of Pine Island, Thwaites, Smith, and Kohler glaciers, West Antarctica, from 1992 to 2011, Geophysical Research Letters “What we do now will determine how quickly Pine Island and Thwaites collapse. A fast transition away from fossil fuels in the next few decades could be enough to put off rapid sea-level rise for centuries. That’s a decision worth countless trillions of dollars and millions of lives. ‘The range of outcomes,’ Bassis says, ‘is really going to depend on choices that people make.’” Twila Moon Research Scientist, University of Colorado, Boulder: There is no question that this is correct. The future rate of ice loss (from Antarctica and elsewhere) is linked to the rate of global warming and that is determined primarily by human activity. A useful reference is Clark et al (2016). Clark et al (2016)Consequences of twenty-first century policy for multi-millennial climate and sea-level change, Nature Climate Change Henning Åkesson Postdoctoral researcher, Stockholm University and Bolin Centre for Climate Research: This is an accurate statement. Talking about uncertainty in these scenarios of sea-level rise, I think the biggest of them all is how global emissions will develop over the next years and decades. What we do now will affect the outcome decades and centuries into the future. We do not know what the tipping points are in these systems, or whether we’ve crossed that line already. It is critical to establish whether retreat may become self-sustainable—that is, once we push the ball off the edge, it may keep rolling downhill even if we reverse current emission trends. That possibility is to me enough to dedicate significant funds and personnel on this problem. Jan Lenaerts Assistant Professor, University of Colorado, Boulder: This is strongly supported by the DeConto and Pollard 2016 Nature paper*, which showed that the Antarctic contribution to committed sea level rise can be limited to ~20 cm in a strong climate mitigation scenario (RCP2.6). DeConto and Pollard (2016)Contribution of Antarctica to past and future sea-level rise, Nature Alexander Robel Assistant Professor, Georgia Tech: The speed of glacier evolution and possibly collapse are certainly modulated by the rate of climatic changes at all points during glacier evolution. The question of specifically where glacier collapse is already underway or where it can be avoided by human choices is currently being investigated by many in the glaciological research community."
https://science.feedback.org/review/guardian-sea-level-rise-cities-fails-make-timescale-clear/,0.5,"The Guardian, by Ruth Michaelson, Richard Luscombe, Niko Kommenda, Justin McCurry, Josh Holder, Jonathan Watts, Helen Roxburgh, Dom Phillips, on 2017-11-03.",,"""The three-degree world: the cities that will be drowned by global warming""",,,,,"This story in The Guardianincludes maps of, and reporting from, five coastal cities that will be affected by continued sea level rise. The story discusses the impact sea level rise will have on those cities, and what they are doing to prepare and adapt. However, scientists who reviewed the story found that it fails to explain one very important thing to readers: nowhere is it explained that the magnitude of sea level rise shown (for a scenario in which the world warms by 3°C) is the amount that would occur after the planet has had centuries to millennia to come into equilibrium with elevated temperatures. Readers are likely to assume that the story’s maps illustrate sea level rise that could occur before the end of the 21st century, but this is not the case.See all the scientists’ annotations in context UPDATE (15 November 2017): The Guardian article has been updated to include some explanation in an expandable box. It states, in part, “How quickly will oceans rise? It could take decades or centuries, but change will be locked in by a 3C temperature rise, which would extensively melt ice caps, shrink glaciers and thermally expand the oceans so many current coastlines and low-lying plains would be under sea level.”REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Chris Roberts Research Scientist, ECMWF/Met Office: The methodology is appropriate, but the time scales involved should have been made clearer. From the original report, “locked in” sea level is defined as “the sustained temperature increase or SLR that will ensue on a time scale of centuries to millennia”. This is not the same as the sea level rise that has already occurred if temperatures reach 3 °C, which is not obvious from the figures or text. Andrew Shepherd Professor, University of Leeds: The Guardian article makes no mention of the timescale over which the “locked-in” sea level rise associated with a 3 °C climate warming would take place. The Climate Central report states that “the sea levels described could possibly, but with low probability, occur sooner than 200 years from now, or be reached as far as 2,000 years in the future”. Most readers would interpret this to mean there is a high probability that the timescale for the associated sea level rise would therefore fall between 200 and 2,000 years. This would have been a useful piece of information for the Guardian article to make clear. I think the Guardian article can be judged as misleading, because the only timescales mentioned are those of the warming and not the consequent sea level rise, and these are not matched. Jeremy Fyke Postdoctoral researcher, Los Alamos National Laboratory: This article provides an excellent visual of an unfortunately very likely general future for humanity, in which sea level rise slowly inundates many coastal cities with accelerating impacts on a vast global population. It is very well presented visually, and does a great job of attempting to link global change (sea level rise) to impacts on individuals and communities—which is practically the whole point of worrying about climate change in the first place. However, one major drawback of this article is that the magnitude and timescale of the sea level rises described in this report are not well explained. This probably leaves readers confused about, for example, what exact level of sea level rise is actually shown in the interactive plots, and over what timescale this could occur. This weakness in turn relates back to the methodology of the single study that underpins this work: Levermann et al, 2013*. In this work, they estimate the final sea level rise that occurs after several thousand years of climate response to greenhouse gas emissions. Unless I’m mistaken, it seems that this magnitude of sea level rise is what is being shown in these figures. (Though this is impossible to verify since no actual sea level rise numbers are printed, I think!) What is shown is not the sea level rise that will occur at year 2100 (as is sort of implied by the presence of figure 1). Thus it is a bit disingenuous to elicit reader reactions to sea level rise plots which represent scenarios that will practically not occur for thousands of years. If we’re talking practical responses to sea level rise in present-day cities, we also need to talk about practically relevant sea level changes (not changes 2,000 years in the future, although these are of profound significance as well). Unfortunately, this article somewhat conflates millennial-scale sea level change with near-term (i.e., decadal to 2100-scale) responses. Regardless, I continue to encourage this type of work by the Guardian to portray complex and critically societally relevant scientific data in a way that is immediately interpretable by the public. Levermann et al (2013) The multimillennial sea-level commitment of global warming, PNAS Jan Lenaerts Assistant Professor, University of Colorado, Boulder: Well-documented and well-referenced article in The Guardian with innovative graphics and a gripping mix of science and personal stories of people living in vulnerable cities. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time."
https://science.feedback.org/review/independent-makes-giant-leap-global-warming-worse-than-thought-single-study-andrew-griffin/,-0.7,"The Independent, by Andrew Griffin, on 2017-10-26.",,"""Climate change might be worse than thought after scientists find major mistake in water temperature readings""",,,,,"This article in The Independent describes a study examining one type of “proxy” record for past global temperatures the geologic record. The study found a potential problem with temperature estimates for time periods tens of millions of years ago, but this article concludes that the study means current climate change is “far worse than previously calculated”. Scientists who reviewed the article explained that this conclusion is not logically connected to the contents of the study. The article exaggerates the study’s implications for records of past climate—there are multiple types of proxy records that have been used to study those time periods— and invents implications for future warming.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Marcus Badger Lecturer in Earth Sciences, The Open University: The article reports on a paper which suggests there may be complications with ONE method we use to determine past ocean temperature. Notwithstanding possible flaws in the methods of the paper, the article ignores significant evidence from other measurements and observations and tells us nothing directly about the severity of future and present climate change. Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: This article takes the results of an experiment and, fuelled by some irresponsible hyperbole from the authors of the study, extrapolates incorrectly to modern climate change. The tone of the article is overly alarmist and unfounded based on the study in question. Mitch Lyle Professor, Sr. Research, Oregon State University: The article has minor inaccuracies reporting a flawed study. The original study has defects. If all the past records of climate warming via oxygen isotopes were wrong, they would need to be buried to the same depth (or at least to the same temperature) to get the common overprint. Depth of burial varies by a huge amount. The study also fails to acknowledge that oxygen isotopes are only one way used to measure ocean temperature. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Featured Annotations: The statements quoted below are from the article; comments and replies are from the reviewers. “Climate change might be worse than thought after scientists find major mistake in water temperature readings The sea was much colder than previously thought, the study suggests, indicating that climate change is advancing at an unprecedented rate” Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: This title and subtitle are totally misleading. The question of whether or not some (and I stress some because this only affects one proxy, not the others that suggest warm temperatures) temperature estimates were wrong has no bearing at all on the rate of current climate change. Marcus Badger Lecturer in Earth Sciences, The Open University: Even if it were correct, there is no direct link between our understanding based on the method discussed in the paper and our understanding of the severity of future and present climate change. The paper does not find a “major mistake” but suggests there may be complications with ONE method used to reconstruct past ocean temperatures. “The research challenges the ways that researchers have worked out sea temperatures until now, meaning that they may be increasing quicker than previously suggested.” Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: I don’t think there’s a link between alteration of deeply buried sediments in this study (i.e., oxygen isotope measurements from millions of years ago) and current rates of temperature increase (directly measured from satellites and weather stations). It may challenge the way we work out sea temperatures (although as I will note later the paper seriously overstates its case), but this doesn’t change the observed rates of change in the post-industrial era. This is inaccurately presented. Marcus Badger Lecturer in Earth Sciences, The Open University: There is no link between the method the paper studies to construct past temperature changes (oxygen isotopes in foraminifera) and present temperature increase (measured using satellites, direct measurements and other proxies). “If true, that means that the global warming we are currently undergoing is unparallelled within the last 100 million years” Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: The study suggests some periods of time may (according to one proxy) be cooler than originally thought, but this doesn’t change the “rate” of warming seen today. This isn’t anything to do with the study. There are confused messages coming out here about rate of change vs. absolute values. Certainly we are not reaching temperatures today that are warmer than over the last 100 million years, either with or without the results of this study. “and [current global warming is] far worse than we had previously calculated.” Marcus Badger Lecturer in Earth Sciences, The Open University: This does not follow logically from the previous sentences. “But [ocean temperatures 100 million years ago] might in fact have stayed relatively stable” Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: “Relatively” being the operative word here. And in any case, there is evidence of warmer poles from other proxies besides oxygen isotopes—organic biomolecule-based proxies (like TEX86), for example. Quite aside from that, there were lush forests where today there is only ice. The fact that the poles were warmer is not something to be called into question by this one study on one proxy, on one type of foraminifera subjected to very high temperatures in the lab. I don’t suggest that this can’t be operating on oxygen isotopes at some level, but given the wealth of other evidence, I suggest the authors of this study, and subsequently the author of this piece, have gone well overboard with their assessment. “‘If we are right, our study challenges decades of paleoclimate research,” said Anders Meibom, the head of EPFL’s Laboratory for Biological Geochemistry and a professor at the University of Lausanne.” Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: It seems the authors of this paper are not au fait with the decades of work that has been done with other proxies that also show warmth at these times, since they take their observed changes in oxygen isotopes in deeply buried and heated sediments, and extend their results outrageously, discounting hundreds of papers on either shallow, well-preserved samples, or organic temperature proxies, or pollen assemblages, or leaf margin analysis, or clumped isotopes—all of which show that the poles were indeed warmer at this time. Marcus Badger Lecturer in Earth Sciences, The Open University: It only potentially challenges ONE method used to reconstruct past temperatures. Other methods and observations based on biomarkers, pollen, large fossils support a much warmer ocean at this time. “Until now, scientists have calculated the temperature of the ancient seas by looking at foraminifera, the fossils of tiny marine organisms found in the sediment on the ocean floor.” Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: This is only one way that scientists have calculated the temperature of the ocean, and they will continue to do so. “But the new research shows that the amount of oxygen in those shells doesn’t actually remain constant over time.” Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: It’s nothing to do with the amount of Oxygen. It’s CaCO3, so oxygen content is pretty much fixed—it’s the isotopic ratio of the oxygen that is incorporated. Marcus Badger Lecturer in Earth Sciences, The Open University: This is a misunderstanding of the way that oxygen isotopes work. “The new research showed that [oxygen isotopes in foraminifera] can change” Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: There is not enough information here. This research specifically only showed that they could change when heated to 300˚C. By not saying what the circumstances are under which the temperature estimates can be altered, the article throws undue doubt on what is in most settings (despite what the authors of the study seem to be suggesting) pretty robust. “This means that the paleotemperature estimates made up to now are incorrect” Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: This is a huge overstatement. It in fact means that some paleotemperature estimates made up to now may be incorrect. An interesting finding, but being over-stated in the extreme. “The changes in the amount of oxygen in the shells isn’t a reflection of changing temperatures – just a consequence of the fact that the amount of oxygen seen changes over time anyway.” Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: It doesn’t just change over time anyway. Firstly, we are talking about the isotope ratio of oxygen, not the amount. Secondly, the authors show evidence that in some depositional settings this sort of “resetting” of temperatures could occur. By over-simplifying here the author of the article loses and obscures the original study. “To revisit the ocean’s paleotemperatures now, we need to carefully quantify this re-equilibration, which has been overlooked for too long. For that, we have to work on other types of marine organisms so that we clearly understand what took place in the sediment over geological time” Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: Or use other temperature proxies to compare with the oxygen isotope data to see if they are consistent—which is what has been done for years. Marcus Badger Lecturer in Earth Sciences, The Open University: There are already other methods based both on different organisms and different proxy methods which the authors ignore."
https://science.feedback.org/review/commentary-australian-ignores-evidence-misrepresents-research-falsely-claiming-humans-not-responsible-climate-change-ian-plimer/,-2,"The Australian, by Ian Plimer, on 2017-10-23.",,"""Misguided renewable energy policies will ruin nation""",,,,,"This opinion in The Australian by Ian Plimer repeats a number of false but common claims to support an argument that human activities are not responsible for climate change, and that renewables like wind and solar cannot effectively replace fossil-fuel-burning power plants. The scientists who reviewed this article found that it lacks scientific credibility. They explain that the author either ignores or is unaware of the abundance of scientific research that directly contradicts his claims about the cause of global warming.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Kenneth Gillingham Associate Professor, Yale University: This article is full of scientific inaccuracies and reveals a weak understanding of energy technologies and markets. Peter Neff Assistant Research Professor, University of Minnesota: Yet another in the exhausting heap of opinions choosing not to engage with evidence, while still expecting readers to believe inaccurate and baseless claims. It is baffling why publications such as The Australian wish to promote opinions that are both not well-argued and demonstrably not based on fact. Sara Vicca Postdoctoral research fellow, University of Antwerp: The article is full of incorrect information and flawed, misleading reasoning. Peer Nowack Independent Research Fellow, Imperial College London: An article that either chooses to ignore scientific arguments, or to take them out of context in order to misuse them. Could not find scientifically accurate and well backed-up claims. Aimée Slangen Researcher, Royal Netherlands Institute for Sea Research (NIOZ): This article is misleading and ignores vast bodies of scientific research on climate change. It uses clearly incorrect statements and/or flawed reasoning to argue in favor of the authors’ opinion on climate change and energy policies. Malte Stuecker Postdoctoral research fellow, University of Washington: The article is full of false statements, many of which have been rebutted multiple times. Nathaelle Bouttes Research scientist, CNRS, Laboratoire des Sciences du Climat et de l'Environnement (LSCE): The article is misleading and presents inaccurate arguments that have no scientific support in the literature. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from the article; comments and replies are from the reviewers. 1.Human activities have unambiguously increased the concentration of greenhouse gases in Earth’s atmosphere since the beginning of the Industrial Revolution. Physics predicts that the unavoidable consequence of that increase is the warming we have observed. “Global human emissions are only 3 per cent of total annual emissions.” Sara Vicca Postdoctoral research fellow, University of Antwerp: Global human emissions are indeed only a small percentage of what ecosystems cycle, but the reasoning is completely flawed. Regarding the impact on climate, it is the net emissions that matter, not the amount of carbon that is being cycled over and over. Terrestrial ecosystems take up and re-emit about 12 times more CO2 than humans emit, and oceans cycle about 9 times more CO2 than we emit. BUT! This carbon uptake and release is more or less balanced at the annual scale, and net ecosystem emissions are even negative. Without these ecosystems, atmospheric CO2 concentration would have risen even more as a consequence of fossil fuel burning; the CO2 concentration in the air would already be around 550 ppm (instead of the current ~400 ppm). Hence, it is absolutely misleading to compare amounts of CO2 cycling through the ecosystems with human CO2 emissions in this context. If anything, the CO2 cycling through the ecosystems should be taken as a reason to safeguard them: if we lose these carbon sinks, CO2 in the air will increase no matter what we do. Ana Bastos Group Leader, Max Planck Institute for Biogeochemistry: This is purposely misleading. Others have commented appropriately. The global carbon budget provides an overview of sources and sinks of CO2 since 1880. Source: Global Carbon Project Peer Nowack Independent Research Fellow, Imperial College London: Others have already commented on this in detail. Just to emphasize: the statement is clearly misleading. What matters here is how human emissions drive the net atmospheric CO2 budget (emissions minus uptake) out of balance, which leads to an accumulation of CO2 in the atmosphere. “It has never been shown that human emissions of carbon dioxide drive global warming.” Peer Nowack Independent Research Fellow, Imperial College London: This sentence essentially ignores many thousands of studies that provide evidence to the contrary (i.e., that human CO2 emissions ARE driving global warming) and is therefore factually wrong. IPCC (2013) Climate Change 2013: The Physical Science Basis Wolfgang Cramer Professor, Directeur de Recherche, Mediterranean Institute for Biodiversity and Ecology (IMBE): Virtually all statements in this article have been proven wrong so many times by scientific experts that it is unreasonable to once again show that they are wrong. But I want to focus on the statement “it has never been shown” only. How can one claim that the impact of anthropogenic greenhouse gas emissions has “never been shown that…”? Clearly, for this author, science per se either does not exist or else has no credibility whatsoever. Surely then, scientific research itself cannot exist, there is no geology to find coal resources, no studies “of natural processes such as ocean degassing”, etc. From this, one can only conclude that we actually cannot know anything—not even the things that this author believes to be true. Aimée Slangen Researcher, Royal Netherlands Institute for Sea Research (NIOZ): This is not true. In fact, there is a vast body of work on detection and attribution, which specializes in exactly this: determining the causes of observed changes in climate. This happens in a two-step process. Step 1 (the detection step) looks at whether observed changes can be explained by internal climate variability. If the answer is no, step 2 (the attribution step) determines which factors explain the observed changes. “natural processes such as ocean degassing, volcanoes, natural chemical reactions and exhalation don’t drive global warming.” Peter Neff Assistant Research Professor, University of Minnesota: Here is a great illustration of how these processes don’t drive warming over the observational period: https://www.bloomberg.com/graphics/2015-whats-warming-the-world/ “In the geological past, Earth’s atmosphere had hundreds of times the CO2 content of the modern atmosphere yet there were no carbon dioxide-driven catastrophes. The past shows that climate change is normal, that warmer times and more atmospheric carbon dioxide have driven biodiversity and that cold times kill.” Peer Nowack Independent Research Fellow, Imperial College London: There are many problems with this statement, starting with an entire lack of accuracy. It reads like a series of generic statements that can easily be taken out of context and are entirely irrelevant to the problem at hand. One particularly striking point is the implicitly obvious lack of awareness for timescales. Atmospheric CO2 concentrations are changing at unprecedented rates now, posing a serious threat to biodiversity in rapidly changing ecosystems. Aimée Slangen Researcher, Royal Netherlands Institute for Sea Research (NIOZ): Indeed, climate change is normal, but there are 2 important differences with respect to the geological record: 1) the current rate of increase in CO2 is unprecedented and 2) the current CO2 increase is caused by human emissions. “Ice core drilling shows that 800 years after natural warming, the atmosphere increases in carbon dioxide” Nathaelle Bouttes Research scientist, CNRS, Laboratoire des Sciences du Climat et de l'Environnement (LSCE): Recent work* shows that the temperature and CO2 rise were synchronous within uncertainties: if there was a lag it was less than 400 years, not 800 years as previously thought. Additionally, the temperature increase over the deglaciation cannot be explained solely by orbitally driven insolation changes (modifications of solar energy received by the Earth due to its position). The radiative effect of the CO2 rise amplifies the warming and explains part of the total deglacial warming. Parrenin et al (2013) Synchronous Change of Atmospheric CO2 and Antarctic Temperature During the Last Deglacial Warming, Science “Instrumental temperature measurements over the past 150 years show no correlation between human emissions of CO2 and ­temperature.” Emmanuel Vincent Founder & Executive Director, Science Feedback: Plotting the relationship between global temperature and the logarithm of atmospheric CO2 concentration shows a strong relationship (figure below). This is predicted by physics* since CO2 is a greenhouse gas. Ian Plimer might be confusing CO2 emissions and CO2 concentration in the atmosphere, which is what matters for explaining Earth’s surface temperature. Figure – Global temperature from Berkeley Earth’s dataset versus atmospheric CO2 concentrations. Huang and Shahabadi (2014) Why logarithmic? A note on the dependence of radiative forcing on gas concentration, Journal of Geophysical Research Atmospheres Peter Neff Assistant Research Professor, University of Minnesota: Instrumental temperature measurements over the last 150 years record weather/climate that is influenced by more than ONLY CO2. Natural variation must also be considered, including semi- to multi-decadal processes involving the ocean and atmosphere (e.g. El Niño-Southern Oscillation). “On all timescales it can be shown that there is no correlation between CO2 emissions and global warming.” Peter Neff Assistant Research Professor, University of Minnesota: This is simply false. Ice cores show correlation over ice age cycles (100,000 years). The modern observational record shows correlation that cannot be reproduced without including greenhouse gases (CO2, CH4, N2O). Climate models demonstrate this correlation very well. If you include only natural climate forcing (volcanoes, solar variations, etc.) over the observational period, models UNDERpredict observed temperatures. If you include only greenhouse gas forcing over the observational period, models OVERpredict observed temperatures. If you include natural, greenhouse gas, and other anthropogenic forcings (including cooling effects of coal/soot pollution particulates), models quite accurately match observations. Comparison between global mean surface temperature anomalies (°C) from observations (black) and AOGCM simulations forced with (a) both anthropogenic and natural forcings and (b) natural forcings only. Source: IPCC “The worldwide temperature record has been changed. Cooling trends have been ‘homogenised’ to warming trends. In the corporate world, if a loss is ‘homo­genised’ to a profit, it is fraud.” Peter Neff Assistant Research Professor, University of Minnesota: This point has been refuted ad nauseam. See Zeke Hausfather’s explaination here: https://www.carbonbrief.org/explainer-how-data-adjustments-affect-global-temperature-records Berkeley Earth independently assessed these records. The adjustments, which are necessary over 150-200 years of measurements of varying type and quality, end up reducing the warming trend over the 20th Century. Ana Bastos Group Leader, Max Planck Institute for Biogeochemistry: Every time new data is assimilated, the record is bound to change slightly. I think the author is referring to a discontinuity in the global temperature record around 1945 that was shown to be due to changes in the instruments after WWII*. Since this discontinuity was reported, new temperature products were corrected for instrumentation change. This is not fraud, just good science. Thompson et al (2008) A large discontinuity in the mid-twentieth century in observed global-mean surface temperature, Nature 2.The author makes inaccurate claims about greenhouse gas emissions in Australia and about renewable energy systems. “[South Australia] has the most expensive electricity in the world.” Kenneth Gillingham Associate Professor, Yale University: This is misleading. It is true that prices have rapidly increased, largely due to high natural gas prices from the start-up of gas liquefaction plants. However, there are plenty of other regions within countries (note South Australia is a region within the country of Australia) with just as high or higher electricity prices. How about villages in Alaska? Small islands? This claim is just misleading. “Unless the laws of physics are changed, solar power cannot be made more efficient.” Kenneth Gillingham Associate Professor, Yale University: This is incorrect. Sure, if you use exactly the same technologies we have today there is a barrier to the efficiency of polycrystalline solar panels. But there are many other technologies in the works that can have much higher efficiency. Lew (2016) Research opportunities to advance solar energy utilization, Science “Construction and maintenance of wind and solar facilities ­release far more carbon dioxide than they are meant to save over their working lives and they need to be sup­ported 24/7 by coal-fired generators.” Kenneth Gillingham Associate Professor, Yale University: This is completely incorrect. There are numerous studies contradicting this. For example, see a series of studies by Sally Benson at Stanford University. Frankly, both parts of this claim are absurd. Coal-fired generators are particularly poorly-suited to act as a backup for solar because they generally are very expensive to ramp up and down, so they are used almost everywhere around the world as baseload generators. Natural gas or hydro are much better suited as backup. This sentence belies a lack of understanding of energy technologies and markets. “[Those who signed the Paris Accord] cannot change Earth’s orbit and radiation released from the sun that drive climate” Aimée Slangen Researcher, Royal Netherlands Institute for Sea Research (NIOZ): The problem we are dealing with here is not the radiation released from the sun, but with the amount of energy that remains in the Earth’s climate system. The amount of energy trapped in the climate system increases due to the presence of greenhouse gases in the atmosphere: rather than shooting the energy back into space, it is used to heat the climate system. Simple physical laws, that make that more greenhouse gases cause a warmer climate. NASA’s Earth Observatory has an extensive explanation. Peter Neff Assistant Research Professor, University of Minnesota: This links back to the author’s earlier claim about ice cores, that they show increasing CO2 after “natural warming.” In this ancient scenario, he is correct that warming was caused by changes in Earth’s orbit around the Sun—which slightly but significantly affects the planetary energy budget. However, it is no longer the case that solely Earth’s orbit and solar radiation drive climate change. Solar energy reaching Earth has been declining for decades, as global average temperatures have continued to increase. Zeke Hausfather has nicely explained this. “Australia’s signed a suicide note [with the Paris Accord] yet didn’t seem to notice that China, India, Indonesia and the US did not commit to reducing their large carbon dioxide emissions.” Sara Vicca Postdoctoral research fellow, University of Antwerp: China and India are actually changing track. They need to because their people are dying of air pollution. And of course they have also realized that renewable energy is more profitable. See here fore much more information: https://www.worldenergy.org/publications/2017/world-energy-issues-monitor-2017/ Statement taken from the full report of 2017: “China is continuing to experience rapid growth in renewable energy capacity, with the country installing 30.8 GW of new wind capacity in 2015, and with government plans in place to build an additional 30.83 GW before the end of 2016. The country’s solar capacity, too, is increasing steadily and China has already overtaken Germany to become the country with the largest cumulative solar PV capacity globally. Regarding future investment in further renewables capacity, China claims the top spot in the 2015 Climatescope project, which ranks 55 emerging economies according to their ability to attract investment in clean energy, and places second globally after the US in Ernst and Young’s 2016 Renewable Energy Country Attractiveness Index.” “The grasslands, crops, forests and territorial waters of Australia absorb more carbon dioxide than Australia emits.” Ana Bastos Group Leader, Max Planck Institute for Biogeochemistry: This is not true. According to the CSIRO (see here): “Taking all fluxes together, the Australian biosphere gained carbon on average at 59 million tonnes of carbon per year (1 Mt = 1 Teragram, Tg) during the period 1990-2011. This amount is the equivalent to 62% of Australia’s emissions from fossil fuels for the same period (this calculation excludes the fossil fuel exports shown in the budget figure).” Source: CSIRO A thorough analysis of the Australian carbon budget can be found in Haverd et al*. Haverd et al (2013) The Australian terrestrial carbon budget, Biogeoscience"
https://science.feedback.org/review/bbc-article-ocean-acidification-accurate-brief-roger-harrabin/,0.7,"BBC, by Roger Harrabin, on 2017-10-23.",,"""More acidic oceans 'will affect all sea life'""",,,,,"This BBC article describes an as-yet-unreleased report on ocean acidification from a major collaborative scientific project called BIOACID. The report will summarize the state of research on the impacts of ocean acidification—the changing pH and chemistry of seawater due to rising atmospheric carbon dioxide—on marine life. Scientists who reviewed the article found that it was generally accurate in its description of the forthcoming report’s overall conclusions that ocean acidification poses an important threat to marine ecosystems. However, the BIOACID report will cover a broad and complex field of research, very little of which is explained in this short article.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Lennart Bach Postdoctoral research fellow, GEOMAR Helmholtz Centre for Ocean Research Kiel: A good summary of BIOACID’s key results. The information provided here is based on peer-reviewed scientific articles. I am glad the author mentions the statement that “[…]even if an organism isn’t directly harmed by acidification it may be affected indirectly through changes in its habitat or changes in the food web.” I think these complex (and so far poorly understood) food web interactions deserve attention by both the public and the scientific community. It is also important that the author mentions that there are potential winners (e.g. macroalgae) in an acidified ocean and that not every organism is negatively affected. Jean-Pierre Gattuso Research Professor, CNRS, Université Pierre et Marie Curie and IDDRI: The German program BIOACID has generated an impressive amount of knowledge on ocean acidification and its impacts. The BBC article is based on a brochure that is not available to me. It does not contain any inaccuracies but only skims the surface of the issue by highlighting a few scientific results with just one sentence. The synthesis of more than 350 publications on the effects of ocean acidification alluded to would deserve an in-depth article to provide important insight and better explain implications of the science. Adam Subhas PhD candidate, Caltech: This article is a well-done presentation of a newly published long-term study on ocean acidification. Such studies are useful for documenting long-term, larger-scale effects and the author seemed to do a pretty good job in stating the findings accurately. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Featured Annotations: The statements quoted below are from the article; comments and replies are from the reviewers. “More acidic oceans ‘will affect all sea life’” Lennart Bach Postdoctoral research fellow, GEOMAR Helmholtz Centre for Ocean Research Kiel: “More acidic” is not entirely correct as the ocean is strictly speaking still alkaline (pH>7) and will remain so in the future. It is nevertheless true that the pH will most likely decrease (and has already done so in the past). A small change in the pH leads to large shifts in seawater carbonate chemistry (as the author correctly mentions later in the main text). The pH change will affect many species. I am not sure if the statement “all sea life” is justified at this stage. Indirect effects will likely play a major role here (as mentioned later in the text) but this still lacks evidence. This is more like “work in progress” I would say. “Since the beginning of the Industrial Revolution, the average pH of global ocean surface waters have fallen from pH 8.2 to 8.1. This represents an increase in acidity of about 26%.” Lennart Bach Postdoctoral research fellow, GEOMAR Helmholtz Centre for Ocean Research Kiel: Correct. “This means the number of baby cod growing to adulthood could fall to a quarter or even a 12th of today’s numbers, the researchers suggest.” Lennart Bach Postdoctoral research fellow, GEOMAR Helmholtz Centre for Ocean Research Kiel: This statement is based on on a study by Stiasny et al*. The authors write: “Here, we obtain first experimental mortality estimates for Atlantic cod larvae under OA and incorporate these effects into recruitment models. End-of-century levels of ocean acidification (~1100 μatm according to the IPCC RCP 8.5) resulted in a doubling of daily mortality rates compared to present-day CO2 concentrations during the first 25 days post hatching (dph), a critical phase for population recruitment. These results were consistent under different feeding regimes, stocking densities and in two cod populations (Western Baltic and Barents Sea stock). When mortality data were included into Ricker-type stock-recruitment models, recruitment was reduced to an average of 8 and 24% of current recruitment for the two populations, respectively. Our results highlight the importance of including vulnerable early life stages when addressing effects of climate change on fish stocks.” The author of the BBC article referred to their work correctly. Stiasny et al (2016) Ocean Acidification Effects on Atlantic Cod Larval Survival and Recruitment to the Fished Population, PLOS ONE “[Riebesell] is a world authority on the topic and has typically communicated cautiously about the effects of acidification.” Adam Subhas PhD candidate, Caltech: This is good to note, as it shows that scientists directly involved in the research are driven by these experiments to speak out about these effects now. “‘But even if an organism isn’t directly harmed by acidification it may be affected indirectly through changes in its habitat or changes in the food web.’” Lennart Bach Postdoctoral research fellow, GEOMAR Helmholtz Centre for Ocean Research Kiel: A very important statement which is often neglected. It is good that the author included this statement. “And some plants – like algae which use carbon for photosynthesis – may even benefit.” Lennart Bach Postdoctoral research fellow, GEOMAR Helmholtz Centre for Ocean Research Kiel: This sentence is not really wrong but imprecise. First, plants use carbon dioxide (or in the case of aquatic photosynthetic organisms CO2 and often bicarbonate). The term “carbon” is too general. Second, the sentence implies that only some plants use carbon dioxide. I am sure the author is aware that “all” plants use CO2 for photosynthesis. Adam Subhas PhD candidate, Caltech: The use of “carbon” here is confusing. However the statement is not totally wrong. It is fine in my opinion to say “some plants maybe benefit” because experiments have only been run on some types of plants and algae."
https://science.feedback.org/review/former-prime-minister-tony-abbott-wrongly-claims-australia-warmed-far-less-data-show/,Inaccurate,"Global Warming Policy Foundation, Tony Abbott, 2017-10-09","unadjusted data suggests that temperatures in Australia have only increased by 0.3 degrees over the past century, not the 1 degree usually claimed",,Factually inaccurate: Observations clearly show that Australia has warmed by around 1 °C. Incorrect: IPCC projections have compared well with the observed warming trend.,"Globally, weather station data show that the world has warmed by roughly 1 °C so far–as has Australia. The warming trend over the last couple decades has matched climate model projections made during that time period.","It may be that a tipping point will be reached soon and that the world might start to warm rapidly but so far reality has stubbornly refused to conform to the Intergovernmental Panel on Climate Change’s computer modelling. [...] So far, though, there’s no concession that their models might require revision even though unadjusted data suggests that the 1930s were actually the warmest decade in the United States and that temperatures in Australia have only increased by 0.3 degrees over the past century, not the 1 degree usually claimed.",,"Peter Thorne Professor, Maynooth University: The global warming signal over the instrumental record is far larger in the unadjusted than the adjusted record. You can’t pick and choose which adjustments you happen to like. Adjustments are essential because observation techniques have changed through time and this introduces data artefacts that are not a true portrayal of the underlying climate. We have tested, replicated, and benchmarked techniques to build confidence in the techniques deployed to account for these. The choice is stark: trust the unadjusted data we know to be wrong and that shows more warming, or trust the adjusted data which has been verified scientifically many times over to improve the estimates and shows less warming. “reality has stubbornly refused to conform to the Intergovernmental Panel on Climate Change’s computer modelling” Markus Donat Research Fellow, University of New South Wales: This claim is wrong. For example, this study by Rahmstorf and colleagues* shows how projections from past IPCC reports (future projections starting in 1990 and 2000) very well predicted the observed temperature changes since then. Figure –Observed annual global temperature, unadjusted (pink) and adjusted for short-term variations due to solar variability, volcanoes and ENSO (red)compared to the scenarios of the IPCC (blue range and lines from the third assessment, green from the fourth assessment report). Source:Rahmstorf et al (2012) Rahmstorf et al (2012) Comparing climate projections to observations up to 2011, Environmental Research Letters “data suggests that the 1930s were actually the warmest decade in the United States” Markus Donat Research Fellow, University of New South Wales: It is true that the eastern part of the US is different than most of the globe with regards to temperature changes. While temperatures have been rising in most regions of the world, the eastern US is known as the so-called “warming hole” because this is one of the few regions where we do not see clear long-term warming. But using this as an argument against global warming is simply nonsense and comparable to picking one rotten cherry out of a bucket with 1,000 otherwise perfect cherries, and claiming the whole bucket of cherries is rotten. The hot temperatures in the 1930s in the US were related to a very specific coincidence of variability patterns favouring the occurrence of hot extremes (see also this study*). But if this coincidence of variability patterns would occur today in a warmer world, the records set in the 1930s would surely be broken also in this region of the world. Donat et al (2016) Extraordinary heat during the 1930s US Dust Bowl and associated large-scale conditions, Climate Dynamics “temperatures in Australia have only increased by 0.3 degrees over the past century, not the 1 degree usually claimed.” Markus Donat Research Fellow, University of New South Wales: I don’t know what the source of these numbers is. The official data for Australia by the Bureau of Meteorology, based on high-quality observations, clearly shows that average temperatures have warmed by 0.9-1 degree since 1910. Source: BOM"
https://science.feedback.org/review/new-york-times-straightforward-answers-common-climate-questions-accurate-justin-gillis/,1.4,"The New York Times, by Justin Gillis, on 2017-09-19.",,"""Climate Change Is Complex. We’ve Got Answers to Your Questions.""",,,,,"This article in The New York Times serves as a primer by briefly answering seventeen basic questions about the cause and consequences of—and possible solutions to—climate change. Thirteen scientists reviewed the article, and generally found the answers to be highly accurate distillations of the research on that topic. There are only a few instances where answers—mainly to questions about efforts to reduce greenhouse gas emissions—are worded in an imprecise way that could lead to readers misunderstanding the state of scientific knowledge.See all the scientists’ annotations in context This is part of a series of reviews of 2017’s most popular climate stories on social media.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Ted Letcher Research Scientist, Cold Regions Research and Engineering Lab: The article provided a quick and remarkably concise “listicle” style explanation of the key questions surrounding climate change. I saw no red flags, or blatant attempts to mislead the reader. Furthermore, every major scientific claim has a link to a peer reviewed article. The article largely avoids hyperbole as well as alarmist and inflammatory language, which is laudable. I also want to highlight the section that talks about the various solutions and opportunities for action. Overall, a good article that hits all the key point, speaks in plain English, and treats the reader with enough respect to look deeper into any one issue. Joeri Rogelj Professor, Centre for Environmental Policy at Imperial College London: The article provides a fair and correct account of the state of the science in my area of expertise. Some statements could be slightly more informative when the article speaks about “experts”. It is not clear who these experts are. In some cases “expert” views are used to support statements which are dependent on societal value judgments, and would benefit from some clarification. Daniel Swain Climate Scientist, University of California, Los Angeles: The accuracy of the climate information provided in this piece is generally quite high. Further, the “question and answer” format distills complex, ongoing scientific conversations into a form more readily accessible to a broad audience. Benjamin Horton Professor, Earth Observatory of Singapore: Climate change is one of the most complex areas of scientific study, so it is understandable that the general public find the topic difficult to grasp. But this article provides the readers of The New York Times the chance of understanding the topic. Lennart Bach Postdoctoral research fellow, GEOMAR Helmholtz Centre for Ocean Research Kiel: The article is well written. The author used little “alarmist” jargon and used “strong” adjectives only in cases where there is good scientific evidence for strong impacts. Devaraju Narayanappa Postdoctoral research fellow, Université de Versailles Saint-Quentin (UVSQ-CEA-CNRS): The article provides a simple answer to overarching questions on global warming/climate change and its footprints. Malte Stuecker Postdoctoral research fellow, University of Washington: The article presents short but accurate statements on climate change and its framing. Victor Venema Scientist, University of Bonn, Germany: As far as I can judge, very accurate. A pleasure to read. There should be more science reporting like this. Frank Vöhringer Dr. rer. pol, Scientist, Ecole Polytechnique Fédérale de Lausanne (EPFL): The article provides an informative overview of climate and climate policy facts with only minor inaccuracies. Ana Bastos Group Leader, Max Planck Institute for Biogeochemistry: Overall the article frames the questions correctly and provides generally good answers. However, it presents some aspects in a rather simplified and incomplete manner (e.g. consequences of global warming or mitigation solutions). Didier Swingedouw Researcher, CNRS (French National Center for Scientific Research): The article is mainly accurate for most of its assertions. Some of them are bit subjective and possibly alarmist, but generally speaking the author is very well informed concerning general understanding that we have of global warming and its impact (as released in IPCC report for instance). Dan Jones Physical Oceanographer, British Antarctic Survey: Although there are places where the language is a little imprecise (e.g. the word “ever” in the statement “Geologists say that humans are now pumping the gas into the air much faster than nature has ever done”), overall the article is an accurate, concise summary of climate change as a scientific and social issue. Kelly McCusker Research Associate, Rhodium Group and Climate Impact Lab: The article does a good job of succinctly answering complex questions without misrepresenting the scientific evidence.Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Featured Annotations: The statements quoted below are from the article; comments and replies are from the reviewers. How much is the Earth heating up? “Climate change? Global warming? What do we call it? […]You can think of global warming as one type of climate change. The broader term covers changes beyond warmer temperatures, such as shifting rainfall patterns.” Daniel Swain Climate Scientist, University of California, Los Angeles: This is a good way to describe the difference in language. It would also be reasonable to say that global warming (the increase in Earth’s average temperature) causes climate change (shifts in the location/frequency/intensity of weather patterns). In practice, the two terms are often used somewhat imprecisely and interchangeably (even in the scientific literature). Kelly McCusker Research Associate, Rhodium Group and Climate Impact Lab: It is also worth noting that global warming refers to global average temperature rising, but this does not necessarily mean that all locations across the globe are warming at all times. “the oceans are rising at an accelerating pace” Kelly McCusker Research Associate, Rhodium Group and Climate Impact Lab: Because more than 90% of the energy added to the climate system is being stored in the ocean, causing sea level rise through thermal expansion. The latest IPCC report states, “Ocean warming dominates the increase in energy stored in the climate system, accounting for more than 90% of the energy accumulated between 1971 and 2010 (high confidence).” “Two degrees is more significant than it sounds. […]The number may sound low, but as an average over the surface of an entire planet, it is actually high” Daniel Swain Climate Scientist, University of California, Los Angeles: This is an important point. “Global mean temperature” (GMT) is a pretty abstract quantity, since it doesn’t reflect any particular location on Earth. Instead, GMT serves as a useful indicator of how much the Earth’s climate has changed overall. While a helpful statistical construct, it masks the fact that the Earth is warming much faster than the global average in some regions (over land, in the Arctic) than in others (over the oceans). Victor Venema Scientist, University of Bonn, Germany: Note that the warming over land is about twice as large as the warming over the ocean. Over the ocean, more of the additional heat goes into evaporation of water rather than warming of the air. It furthermore takes time to heat up the oceans, just like a water kettle takes time to boil. Because there is more land in the Northern Hemisphere, it will warm more than the Southern Hemisphere. One way to see how much of a difference two degrees makes is to look at a region closer to the equator that is two degrees warmer. Nature will look very different. “We’ve known about [the greenhouse effect] for more than a century. Really.” Daniel Swain Climate Scientist, University of California, Los Angeles: As the author correctly notes, the underlying chemistry dates back to the late 1880s. “The first prediction that the planet would warm as humans released more of the gas was made in 1896.” Ed Hawkins Principal Research Fellow, National Centre for Atmospheric Science: Arrhenius didn’t actually discuss human emissions in 1896—he was speculating about causes of the ice ages. But, he did effectively make a prediction that warming would occur if carbon dioxide levels increased (whatever their source). “[CO2] has increased 43 percent above the pre-industrial level so far” Lennart Bach Postdoctoral research fellow, GEOMAR Helmholtz Centre for Ocean Research Kiel: Indeed! I get to a slightly different number, however, (45 %) maybe because I used a different basis (280 ppm) and/or current CO2 value (i.e., 405 ppm from Maona Loa, August 2017). The message is correct! How do we know humans are responsible for the increase in carbon dioxide? “Hard evidence, including studies that use radioactivity to distinguish industrial emissions from natural emissions, shows that the extra gas is coming from human activity.” Victor Venema Scientist, University of Bonn, Germany: Also important is that we have good estimates of how much fossil fuel we have burned, from which one can estimate the CO2 emissions. The increase in CO2 concentration in the atmosphere is about half of those emissions (the rest was taken up by the vegetation and the oceans). It would have been more accurate to say that we can see that the CO2 increase is from burning fossil fuels by measuring isotopes (differences in the number of nuclear particles of atoms). Not all relevant isotopes are radioactive and the ones that are only a little. “Geologists say that humans are now pumping the gas into the air much faster than nature has ever done.” Daniel Swain Climate Scientist, University of California, Los Angeles: “Ever” is a long time, and it’s not clear this is strictly true for the entire length of Earth’s history. But there is strong evidence that this statement is true for all human-relevant timescales: in other words, the rate of CO2 emissions caused by humans is unprecedented since the age of the dinosaurs (i.e., at least 66 million years ago*). Zeebe et al (2016) Anthropogenic carbon release rate unprecedented during the past 66 million years, Nature Could natural factors be the cause of the warming? “Could natural factors be the cause of the warming? Nope.” Victor Venema Scientist, University of Bonn, Germany: We are sure that natural factors alone could not have caused the observed warming—without the increase of greenhouse gases there would not be so much warming—but they could have contributed. For the period 1951 to 2010 our best estimate is that all of the warming was due to human activities. But natural factors could have warmed or cooled the Earth a bit. In the period around 1900, part of the warming was probably natural due to fewer volcanic eruptions and a stronger Sun. [Also see this related Claim Review. ] “The warming is extremely rapid on the geologic time scale, and no other factor can explain it as well as human emissions of greenhouse gases.” Daniel Swain Climate Scientist, University of California, Los Angeles: This accurate statement succinctly summarizes decades of scientific research across a wide range of disciplines. Why do people deny the science of climate change? “Instead of negotiating over climate change policies and trying to make them more market-oriented, some political conservatives have taken the approach of blocking them by trying to undermine the science.” Victor Venema Scientist, University of Bonn, Germany: This is mostly just in the USA. In the rest of the world, conservative parties accept the science of climate change. Ana Bastos Group Leader, Max Planck Institute for Biogeochemistry: On the scientific community side, the consensus is broad. It’s worth revisiting Cook et al. 2015*. In their review they find a 97% consensus about human-induced global warming in published climate studies. Cook et al (2016) Consensus on consensus: a synthesis of consensus estimates on human-caused global warming, Environmental Research Letters What could happen? “Over the coming 25 or 30 years, scientists say, the climate is likely to gradually warm” Ted Letcher Research Scientist, Cold Regions Research and Engineering Lab: While the exact details and timing of warming are subject to unpredictable decadal (semi-decadal) climate variability (e.g. El Niño Southern Oscillation, Pacific Decadal Oscillation, Atlantic Multidecadal Oscillation), this statement is largely true. “Longer term, if emissions rise unchecked, scientists fear climate effects so severe that they might destabilize governments, produce waves of refugees, precipitate the sixth mass extinction of plants and animals in the Earth’s history, and melt the polar ice caps, causing the seas to rise high enough to flood most of the world’s coastal cities. The emissions that create those risks are happening now, raising deep moral questions for our generation.” Ed Hawkins Principal Research Fellow, National Centre for Atmospheric Science: This paragraph suggests that the emissions that will precipitate the sixth mass extinction are happening now, which I think is misleading. We can stop those impacts by reducing our emissions. How much will the seas rise? “The ocean has accelerated and is now rising at a rate of about a foot per century[…] The risk is that the rate will increase still more. Scientists who study the Earth’s history say waters could rise by a foot per decade in a worst-case scenario, though that looks unlikely. Many experts believe that even if emissions stopped tomorrow, 15 or 20 feet of sea level rise is already inevitable, enough to flood many cities unless trillions of dollars are spent protecting them. How long it will take is unclear. But if emissions continue apace, the ultimate rise could be 80 or 100 feet.” Benjamin Horton Professor, Earth Observatory of Singapore: It is accurate to say sea-level rise is approximately one foot per century. Present-day sea-level rise is a major indicator of climate change. Since the early 1990s, sea level rose at a mean rate of ~3.1 mm/yr (~1 foot over 100 years). It is virtually certain that global mean sea level rise will continue for many centuries beyond 2100, with the amount of rise dependent on future emissions. The latest IPCC report estimates 1 to more than 3 m (up to ~10 feet) for high emission scenarios by 2300. But, those projections of sea-level rise may be limited by uncertainties surrounding the response of the Greenland and Antarctic ice sheets. For example, the report projected a likely contribution of the Antarctic ice sheet (AIS) of -8 to +15 cm under the high emissions scenario by 2100, but a recent coupled ice sheet and climate dynamics model suggests that the AIS could contribute more than 1 m by 2100, and more than 10 m by 2300, under that high emissions scenario. Is recent crazy weather tied to climate change? “Is recent crazy weather tied to climate change? Some of it is.” Daniel Swain Climate Scientist, University of California, Los Angeles: This is a reasonable short answer to an extremely challenging scientific question. “Scientists have published strong evidence that the warming climate is making heat waves more frequent and intense. It is also causing heavier rainstorms” Ana Bastos Group Leader, Max Planck Institute for Biogeochemistry: It is hard to attribute each particular event to human-induced climate change. The article correctly frames the influence in terms of increasing frequency and intensity of extremes, and directs the reader to a good reference page with clear explanations for non-experts. Daniel Swain Climate Scientist, University of California, Los Angeles: Indeed, there is now observational evidence that global warming has already increased the likelihood and magnitude of extreme heat and intense downpours across much of the globe*. Diffenbaugh et al (2017) Quantifying the influence of global warming on unprecedented extreme climate events, PNAS “In many other cases, though — hurricanes, for example — the linkage to global warming for particular trends is uncertain or disputed.” Daniel Swain Climate Scientist, University of California, Los Angeles: The question of whether global warming will affect the frequency of hurricanes is indeed an open one, and research continues. There is stronger evidence, however, that warming will increase the maximum “intensity ceiling”/intensification rate1 of the strongest storms, the maximum rainfall associated with tropical cyclones2, and the magnitude of oceanic “storm surges”3 that occur in an era of rising seas. 1- Emanuel (2017) Will Global Warming Make Hurricane Forecasting More Difficult?, BAMS 2- Scoccimarro et al (2017) Tropical Cyclone rainfall changes in a warmer climate 3- Lin et al (2016) Hurricane Sandy’s flood frequency increasing from year 1800 to 2100, PNAS Are there any realistic solutions to the problem? “But as long as there are still unburned fossil fuels in the ground, it is not too late to act.” Joeri Rogelj Professor, Centre for Environmental Policy at Imperial College London: This statement is imprecise, and depends on value judgments of what “too late” means. Even emitting only a fraction of the available unburned fossil fuels would eliminate important ecosystems like coral reef habitats. For these ecosystems it will thus be too late. Because part of the CO2 that is emitted will remain in the atmosphere for many centuries, climate change constitutes a cumulative problem. Halting CO2 emissions before the last fossil fuel has been burned thus indeed commits the world to less impacts than the theoretically maximum. However, whether this is not “too late” depends on whether no irreversible or societally unacceptable impacts were reached before that point. The latter requires societal value judgments informed by scientific assessments, but is ultimately not a scientific question. Frank Vöhringer Dr. rer. pol, Scientist, Ecole Polytechnique Fédérale de Lausanne (EPFL): This is incorrect, at least if we want to stay anywhere near the 2 degree C target. Especially coal reserves are so abundant (and there is coal gasification and coal liquefaction) that by far the largest part of them have to stay in the ground. “The warming will slow to a potentially manageable pace only when human emissions are reduced to zero.” Joeri Rogelj Professor, Centre for Environmental Policy at Imperial College London: The current understanding of interactions between the global carbon cycle and the climate system is that when global CO2 emissions are reduced to zero, the warming will remain approximately constant. This is very often confused by estimates of committed “warming in the pipeline” which instead of assuming that global emissions are reduced to zero, assume that concentrations (and therewith to a large degree forcing) are kept constant. Keeping CO2 concentrations constant would require continuous emissions of CO2 that perfectly counter the uptake by natural sinks. If CO2 emissions are reduced to zero, atmospheric CO2 concentrations will gradually decline. For heat-trapping emissions other than CO2, the requirement to reduce them to zero to stabilize warming depends on their residence time in the atmosphere. For gases and particles that only stay in the atmosphere for shorter time periods (days to a decade) achieving constant emissions would also achieve approximately stabilized warming. “But experts say the energy transition needs to speed up drastically to head off the worst effects of climate change.” Joeri Rogelj Professor, Centre for Environmental Policy at Imperial College London: This is correct. While many countries show gradual declines in their emissions, global emissions are not yet declining. The past few years, global annual CO2 emissions have not increased as much as they did previously and remained roughly constant. However, to halt global mean temperature rise annual CO2 emissions have to become zero. Does clean energy help or hurt the economy? “Converting to these cleaner sources [of energy] may be somewhat costlier in the short term, but they could ultimately pay for themselves by heading off climate damages and reducing health problems associated with dirty air.” Kenneth Gillingham Associate Professor, Yale University: The basic idea of this sentence is correct—that these cleaner sources may be somewhat costlier in the short run, but they also provide benefits that offset the short-run costs. The second part of the sentence is technically correct given that it uses the word “could,” which provides a lot of leeway. A more complete story is that a switch towards these cleaner technologies on the margin for electricity would pay for itself given reasonable estimates of the health costs of fossil fuel generation and the social cost of carbon. It’s also worth noting though that an immediate switch entirely to these technologies would incur transition costs that would likely tip the balance in the cost-benefit analysis, depending on the social cost of carbon used and what sectors we are talking about (are we talking about just electricity? industry? transport?). The vagueness of the statement means that it is less meaningful, but more difficult to critique. Ana Bastos Group Leader, Max Planck Institute for Biogeochemistry: The article does not mention the huge subsidies to the fossil fuel industry worldwide. According to the World Energy Outlook 2016, fossil-fuel subsidies were around $325 billion in 2015 ($490 billion in 2014) against 150 billion for renewables. “Burning gas instead of coal in power plants reduces emissions in the short run, though gas is still a fossil fuel and will have to be phased out in the long run.” Frank Vöhringer Dr. rer. pol, Scientist, Ecole Polytechnique Fédérale de Lausanne (EPFL): It is arguable whether natural gas is a reasonable solution even in the short run. I argued in favor of this 20 years ago, but nowadays we have to cut emissions more drastically than would be possible by switching to another fossil fuel. The CO2 coefficient of natural gas is still about 2/3 of that of coal. Efficiency factors of power plants are also somewhat better for natural gas than for coal. Overall, we might save a bit more than half of the emissions by switching to natural gas while renewables can save much more. Furthermore, given the long technical lifetime of power stations, the “short run” could easily extend to 2060 or more. “‘Clean coal’ is an approach in which the emissions from coal-burning power plants would be captured and pumped underground.” Joeri Rogelj Professor, Centre for Environmental Policy at Imperial College London: It is important to note that up to the present, the capture of CO2 is not perfect. While theoretically some CO2 emissions could be avoided, a residual amount would still leak into the atmosphere. As CO2 accumulates in the atmosphere, it would either lead to continued (yet slower) warming, or have to be compensated by the active removal of CO2 from the atmosphere, which is also not yet proven to work economically. “some countries are already talking about banning the sale of gasoline cars after 2030” Frank Vöhringer Dr. rer. pol, Scientist, Ecole Polytechnique Fédérale de Lausanne (EPFL): It’s not only talk. Great Britain has already decided in favor of such a ban by 2040. Climate change seems so overwhelming. What can I personally do about it? “Experts say the problem can only be solved by large-scale, collective action” Kenneth Gillingham Associate Professor, Yale University: This is correct. Our atmosphere is a global public good and addressing the issue requires large-scale action by most players. “Entire states and nations have to decide to clean up their energy systems” Kenneth Gillingham Associate Professor, Yale University: This is correct. It cannot be done by only a few nations—it requires collective action to make a substantial difference. “Entire states and nations have to decide to clean up their energy systems, using every tool available and moving as quickly as they can.” Kenneth Gillingham Associate Professor, Yale University: This is not universally agreed upon by experts. The key issue is that it is imprecisely written. I would not be surprised if the intent is correct. But taking it as it is written, it is not clear what “every tool available” includes. Technically, this should include truly everything, including simply shutting down all manufacturing that uses fossil fuels at all. Banning the driving of any vehicle except electric vehicles run on renewables. Banning flying. I doubt that was the intent of the sentence. The same issue holds for “moving as quickly as they can.” What are the limits to”as quickly as they can”? Does it including shutting down the economy? Or is the intended sentence “moving as quickly as they cost-effectively can”? Thus, in short, while the idea is correct, this is imprecisely worded and can easily be critiqued. Ana Bastos Group Leader, Max Planck Institute for Biogeochemistry: “Using every tool available” is highly debatable, as even tools which are usually perceived to help mitigating climate (e.g. reforestation), may not result in mitigation effects, depending on how they are implemented. A study on European forests* has shown that afforestation since 1750 was responsible for an increase of 0.12 watts per square meter in the radiative imbalance at the top of the atmosphere, rather than a decrease, because of management choices. Naudts et al (2016) Europe’s forest management did not mitigate climate warming, Science “You can plug leaks in your home insulation to save power, install a smart thermostat, switch to more efficient light bulbs, turn off unused lights, drive fewer miles by consolidating trips or taking public transit, waste less food, and eat less meat.” Ana Bastos Group Leader, Max Planck Institute for Biogeochemistry: According to a recent study*, having fewer children has the largest impact on personal carbon footprint. Wynes and Nicholas (2017) The climate mitigation gap: education and government recommendations miss the most effective individual actions, Environmental Research Letters"
https://science.feedback.org/review/daily-wire-article-incorrectly-claims-climate-models-have-overestimated-warming/,Incorrect,"The Daily Wire, James Barrett, 2017-09-19",climate models have overestimated the amount of global warming and failed to predict what climatologists call the warming ‘hiatus’,,"Factually inaccurate: Observed temperatures have actually stayed within the range of model projections. Misleading: Climate model projections show average long-term trends—by nature they will not ""predict"" short-term variability such as the ""hiatus"" period.","Climate models have, in fact, successfully projected the rate of global warming, comparing well with observed global temperature in recent years. The idea that models should be faulted for not predicting the ""hiatus""—the period in the early 2000s during which temperatures stayed below the long-term trend—reflects a misunderstanding of what a model projection is. ","climate models have overestimated the amount of global warming and failed to predict what climatologists call the warming ‘hiatus’, over 20 years of almost no change in temperatures.",,"Pierre Friedlingstein Professor, University of Exeter: Except that the report (the paper published in Nature Geoscience) never said that. The paper does not describe modelled warming vs. observations over the “hiatus” period. Ed Hawkins Principal Research Fellow, National Centre for Atmospheric Science: Recent media headlines have again discussed the issue of whether climate models are overly sensitive to greenhouse gases. These headlines have misinterpreted a study by Millar et al. which was discussing carbon budgets to limit global temperature rise to 1.5°C above pre-industrial levels. A recent study by Medhaug et al. analysed the issue of how the models have performed against recent observations at length and largely reconciled the issue. An overly simplistic comparison of simulated global temperatures and observations might suggest that the models were warming too much, but this would be wrong for a number of reasons. In the Medhaug et al. paper they show the range of models (blue shading in figure with median in light blue), compared with the HadCRUT4 observations and their estimated uncertainty (orange shading with light orange line). There are a number of well understood reasons why the light orange line might not follow the light blue line, namely: radiative forcings, variability, observational biases and choice of reference period. [Read more…] Figure 5 from Medhaug et al. showing CMIP5 simulations and observations (HadCRUT4) of global temperature. Medhaug et al (2017) Reconciling controversies about the ‘global warming hiatus’, Nature Markus Donat Research Fellow, University of New South Wales: [This comment comes from an evaluation of a similar statement.] For one example, this study by Rahmstorf and colleagues* shows how projections from past IPCC reports (future projections starting in 1990 and 2000) very well predicted the observed temperature changes since then. Figure –Observed annual global temperature, unadjusted (pink) and adjusted for short-term variations due to solar variability, volcanoes and ENSO (red)compared to the scenarios of the IPCC (blue range and lines from the third assessment, green from the fourth assessment report). Source:Rahmstorf et al (2012) Rahmstorf et al (2012) Comparing climate projections to observations up to 2011, Environmental Research Letters Reto Knutti Professor, ETH Zürich: [This comment comes from an evaluation of a similar statement.] Statements that climate models overestimate the warming in response to CO2are incorrect; they are based on either too short time periods that are dominated by natural variability, by the comparison of models with datasets that do not have global coverage, by comparing to models that were run many years ago with emissions and forcings that differed from what actually happened, by the use of oversimplified energy balance models1, or a combination of these. Recent studies have shown that once the changes in climate feedbacks over time2, datasets with full coverage3,and all forcings are considered, the agreement between predicted and observed warming is excellent, even over the recent hiatus period4. It is remarkable that even projections made decades ago with climate models that were much simpler (and were running on computers that were likely slower than a mobile phone today) were quite accurate5,6,7. 1- Knutti and Rugenstein (2015) Feedbacks, climate sensitivity and the limits of linear models, Philosophical Transactions of the Royal Society A 2- Armour (2017) Energy budget constraints on climate sensitivity in light of inconstant climate feedbacks, Nature Climate Change 3- Richardson et al (2016) Reconciled climate response estimates from climate models and the energy budget of Earth, Nature Climate Change 4- Medhaug et al (2017) Reconciling controversies about the ‘global warming hiatus’, Nature 5- Stouffer and Manabe (2017) Assessing temperature pattern projections made in 1989, Nature Climate Change 6- Fischer and Knutti (2016) Observed heavy precipitation increase confirms theory and early models, Nature Climate Change 7- Allen et al (2013) Test of a decadal climate forecast, Nature Geoscience"
https://science.feedback.org/review/daily-wire-article-misunderstands-study-carbon-budget-along-fox-news-telegraph-daily-mail-breitbart-james-barrett/,-1.7,"The Daily Wire, by James Barrett, on 2017-09-19.",,"""Climate Scientists: Climate Models Have Overestimated Global Warming""",,,,,"This story at The Daily Wire describes a new study that evaluates the remaining amount of greenhouse gas that we can emit before global temperature rises to 1.5 °C above pre-industrial times. The study suggests that we may have a little more room in the so-called “carbon budget” than previously estimated. Scientists who reviewed the Daily Wire article found that it greatly misinterpreted the study by saying that it showed that climate projections have overestimated warming. This is incorrect. The study does not conclude that climate models are overly sensitive to warming, or that future warming will be less than projected. Instead, it investigates a discrepancy between the total amount of greenhouse gas emitted since the Industrial Revolution in the models and in the real world. This difference in estimated past emissions affects the study’s calculation of the remaining “carbon budget” for future emissions. According to the study’s authors, articles implying their work “indicates that global temperatures are not rising as fast as predicted” (as published in Fox News, The Telegraph, The Daily Mail, Breitbart…) do not represent their work. Describing the inaccurate coverage of their study, two of the authors wrote, “Crucially, the reason for the correction [of the carbon budget] was not that we had a new estimate of the climate response, or warming per tonne of CO2 emitted—we used exactly the current consensus range—but that we took better account of past emissions and where human-induced warming has got to already.”See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Andrew MacDougall Assistant Professor, St. Francis Xavier University: The article selectively quotes from interviews and scientific papers to create the false perception that climate models significantly overestimate the rate of warming. The article also falsely implies that the cited paper is about the so called “hiatus” while the paper is actually about the carbon budget for the 1.5 ºC target. Pierre Friedlingstein Professor, University of Exeter: [Prof. Friedlingstein is a co-author of the Millar et al study described by the Daily Wire story.] Bad coverage of the Nature Geoscience article. The title and first 3 paragraphs are misleading. It seems very clear that the author of this article did not read the scientific article he is reporting on. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Featured Annotations: “Climate Models Have Overestimated Global Warming” Pierre Friedlingstein Professor, University of Exeter: The title does not truly reflect the article in Nature Geoscience. The issue is not that the models are too warm by 2015. CMIP5 models are on the warm end, yes, but that’s not the main issue here. The article explains that problem comes when looking at both cumulative CO2 emissions and associated warming. The cumulative CO2 emissions simulated by the models only reach 545 GtC (the present-day value) after 2020, by which time the CMIP5 ensemble-mean human- induced warming is over 0.3 ºC warmer than the central estimate for human-induced warming to 2015. “The models end up with a warming which is larger than the observed warming for the current emissions.” Pierre Friedlingstein Professor, University of Exeter: That’s a more accurate description of the study. “For the current emissions” is the key element. “the climate models have overestimated the amount of global warming and failed to predict what climatologists call the warming ‘hiatus’” Pierre Friedlingstein Professor, University of Exeter: Except that the report (the paper published in Nature Geoscience) never said that. The paper does not describe modelled warming vs. observations over the “hiatus” period. Ed Hawkins Principal Research Fellow, National Centre for Atmospheric Science: Recent media headlines have again discussed the issue of whether climate models are overly sensitive to greenhouse gases. These headlines have misinterpreted a study by Millar et al. which was discussing carbon budgets to limit global temperature rise to 1.5°C above pre-industrial levels. A recent study by Medhaug et al. analysed the issue of how the models have performed against recent observations at length and largely reconciled the issue. An overly simplistic comparison of simulated global temperatures and observations might suggest that the models were warming too much, but this would be wrong for a number of reasons. In the Medhaug et al. paper they show the range of models (blue shading in figure with median in light blue), compared with the HadCRUT4 observations and their estimated uncertainty (orange shading with light orange line). There are a number of well understood reasons why the light orange line might not follow the light blue line, namely: radiative forcings, variability, observational biases and choice of reference period. [Read more…] Figure 5 from Medhaug et al. showing CMIP5 simulations and observations (HadCRUT4) of global temperature. Medhaug et al (2017) Reconciling controversies about the ‘global warming hiatus’, Nature “The report, published in the journal Nature Geoscience on September 18, acknowledges that most of the models of warming trends failed to predict the ‘slowdown’ in warming post-2000, resulting in less pronounced warming than predicted and thus more room in the CO2 ‘emissions budget’ for the coming decades.” Andrew MacDougall Assistant Professor, St. Francis Xavier University: Millar et al. (2017) does not mention the “hiatus” nor a slow-down in global warming post 2000, but is instead focused on estimating the remaining carbon budget compatible with remaining below the 1.5 ºC target set by the Paris agreements. Instead of looking at the carbon budget from pre-industrial times to present, the study uses the present decade (2010-2019) as the reference period and asks: How much more CO2 can we emit and remain below an addition 0.6 ºC of warming? The study found that the remaining carbon budget for the 1.5 ºC target was about ~200 GtC, which is larger than that found using pre-industrial times as the reference period. This implies that either (1) models may underestimate the historical strength of natural carbon sinks, (2) that the historical cumulative CO2 emissions (545±150 GtC, 2 standard deviations) are at the low end of the uncertainty bound, (3) or a combination of these and other factors. Ana Bastos Group Leader, Max Planck Institute for Biogeochemistry: There is an ongoing discussion about the reasons for models to overestimate the rates of tropospheric temperature in the early 21st century. In a recent study, Santer and colleagues* show that the observed cooling relative to the model predictions could be explained by both internal variability in the climate system (transition to a negative phase of the Interdecadal Pacific Oscillation in ca. 1999 and other modes) and by systematic errors in the models’ forcing that lead to an overestimation of the radiative forcing in the early 21st century. These errors include a later start of a minimum in solar cycle activity than have been assumed in CMIP5 simulations, and the cooling effect of both human and natural aerosol emissions. Schmidt and colleagues* have shown that if adjusted for such effects, CMIP5 models reproduced the slow-down of the warming trends (figure below). Source: Schmidt et al (2014)* Santer et al (2017) Causes of differences in model and satellite tropospheric warming rates, Nature Geoscience Schmidt et al (2014) Reconciling warming trends, Nature Geoscience “over 20 years of almost no change in temperatures” Ana Bastos Group Leader, Max Planck Institute for Biogeochemistry: Bastos There has been a slow-down in global mean surface (troposphere) temperatures, but this does not call into question the fact that the Earth-system as a whole is warming. In fact, during the so-called “hiatus”, the net radiation imbalance in the top of the atmosphere persisted (implying that warming would continue even if emissions were to stop). In fact, at the same time that warming in the troposphere stalled, ocean heat content increased, especially in deeper layers: The fact that oceans took more heat from the atmosphere helps to explain the slow-down of warming at the surface. This seems to be, at least partly, explained by natural variability in the ocean (see here). Trenberth* argued, thus, that natural variability in the climate system makes the global mean surface temperature record increase in steps, rather than in a linear way. In another study, Yan and colleagues* analysed the redistribution of heat during the “hiatus” period and concluded that: “[…] the term ‘global warming hiatus’ is a misnomer, although we will continue to use the widely used phrase to describe the slowdown or pause in the increase of GMST in the late 20th to early 21st century, with quotation marks. Alternatively, we would like to suggest to the climate community to use ‘global surface warming slowdown’ instead in the future to avoid confusion. There is no absolute consensus on the specific oceanic sink for the excess heat that led to the slowdown in rising GMST (the Southern Ocean may be worth further attention though), but there is a general agreement in this group and in the literature that rather than a ‘global warming hiatus,’ the slowdown of GMST increase in 1998–2013 was a result of the increased uptake of heat energy by the global ocean during those years.” Trenberth (2015) Has there been a hiatus?, Science Yan et al (2016) The global warming hiatus: Slowdown or redistribution?, Earth’s Future “The report follows a study by another team of climate scientists published in June 2017 [Santer et al] that likewise determined that the actual increases in warming post-2000 was ‘generally smaller than trends estimated’ from the models.” Andrew MacDougall Assistant Professor, St. Francis Xavier University: Santer et al. (2017)* attributed the small discrepancy between climate model simulated warming and observed warming to differences in scenario forcing. (i.e., the trajectory of CO2, methane, other greenhouse gasses and aerosols) The models were given the forcing that actually transpired between year 2000 and the present day. That is, the study suggested that the discrepancy is not a problem with our models but a problem with measuring emissions of forcing agents and discrepancies between future scenarios and what actually transpired since the scenarios were designed. Santer et al (2017) Causes of differences in model and satellite tropospheric warming rates, Nature Geoscience “The team of climate scientists notes that in failing to predict the warming ‘hiatus’ in the beginning of the 21st century, the Intergovernmental Panel on Climate Change (IPCC) models overestimated temperature increases…” Pierre Friedlingstein Professor, University of Exeter: The word hiatus is not even mentioned in the paper! Prof. Piers Forster, one of the authors of the Millar et al study, asked by Carbon Brief to further clarify some of the paper’s findings and methodologies in light of the media coverage: Our paper focused on carbon emissions and the feasibility of limiting future warming to 1.5 ºC. We concluded that we would only succeed with strengthened policies to bring rapid and sustained emission reduction. We made estimates of the allowable future emissions of carbon before we pass 1.5 ºC. To do this we made assumptions about past warming, exploring different levels of warming from 2015 to address the role of uncertainty in historic warming levels. Readers should note that our method is only one way of computing the budget. The IPCC special report on 1.5 ºC will need to consider it alongside other lines of evidence. The usefulness of the carbon budget concept will also likely be assessed given its inherent uncertainty due to the uncertain historic warming. I think some press reporting is misleading as our paper did not assess climate impacts or climate model performance. Rather, our paper confirms the need for much increased urgent action from around the world if society stands a chance of limiting warming to 1.5 ºC."
https://science.feedback.org/review/global-warming-fire-suppression-practices-boost-wildfires-us-west-correctly-reported-the-atlantic-robinson-meyer/,2,"The Atlantic, by Robinson Meyer, on 2017-09-07.",,"""Has Climate Change Intensified 2017’s Western Wildfires?""",,,,,"This story in The Atlantic describes the conditions that have contributed to this year’s widespread wildfires in the western United States, including the influence of a changing climate. Scientists who reviewed the story found that it was an accurate summary of the factors involved in this fire season—warm temperatures as well as past fire-suppression practices that have increased the density of fuel available for fires to burn.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Logan Berner Assistant Research Professor, Northern Arizona University: The article provides an excellent summary of how rising air temperatures are leading to drier conditions and more fire activity among forests in parts of the western United States. The article is strengthened by including multiple interviews with scientists who have produced seminal studies of fire-climate interactions in this region. One minor error is that the “paper published in Science last year” was actually published in 2006, not 2016, yet this oversight detracts little from the overall accuracy of the article. Ben Poulter Research Scientist, NASA: The article highlights clearly the challenges that scientists and managers face in disentangling how changes in ignitions, fuel loading, past-management legacies and climate interact to start and sustain fires. William Anderegg Associate Professor, University of Utah: The article is well-supported by the peer-reviewed literature. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Featured Annotations: The statements quoted below are from the article; comments and replies are from the reviewers. “How did a wet Western winter lead to a sky-choking summer?The answer lies in the summer’s record-breaking heat, say wildfire experts. Days of near-100-degree-Fahrenheit temperatures cooked the Mountain West in early July, and a scorching heat wave lingered over the Pacific Northwest in early August.” Logan Berner Assistant Research Professor, Northern Arizona University: Exceptionally high summer air temperatures undoubtedly contributed to the extensive forest fire activity that occurred during the summer of 2017 in the western United States. Forest flammability is affected by both winter snowfall and seasonal rain, as well as by spring and summer air temperatures that regulate the timing of snowmelt and how much water the atmosphere will suck out of the forest.“the total area burned in the western United States over the past 33 years was double the size it would have been without any human-caused warming.” Anthony LeRoy Westerling Associate Professor, University of California, Merced: I would say: “the total area burned in the western United States over the past 33 years was at least double the size it would have been without any human-caused warming.” “Fires have not only been increasing in size due to climate change. In the early 20th century, state and federal governments began aggressively fighting wildfires and trying to keep them as small as possible. This has caused denser and more fire-prone forests than the long-term average for the West, which has led to more massive and uncontrollable fires.” Logan Berner Assistant Research Professor, Northern Arizona University: This statement should have included a citation and also noted that the influence of fire suppression on subsequent fire activity varies with the frequency of historical fires. The century of fire suppression has potentially increased fuel accumulation in dry forests that historically experienced very frequent fires (e.g. every 5-20 years). On the other hand, fire suppression has likely had far less of an impact on wetter forests, such as those in coastal Oregon and Washington, that historically went centuries without fire."
https://science.feedback.org/review/incorrect-claim-global-warming-mostly-natural-based-on-study-that-cant-support-conclusion-jennifer-marohasy-john-abbot/,Incorrect,"The Spectator, Jennifer Marohasy, 2017-08-21",Most of the recent warming could be natural,,"Unsupported: The methods of this study, published in the journal GeoResJ, do not provide evidence for its claim that humans are not the primary cause of global warming.  Cherry-Picking: The study relied on several local records of past climate rather than a global compilation, and failed to account for the important difference between local and global temperature change and variability.","Natural changes in climate cannot explain recent global warming, while the human-caused increase in greenhouse gas concentrations matches the observed warming well. The analysis contained in this paper—which includes important mistakes—does not demonstrate that natural cycles are responsible for modern climate change.","Most of the recent warming could be natural [...] we suggest that at most, the contribution of industrialisation to warming over the twentieth century would be in the order of 0.2°C. [...] we also calculate an Equilibrium Climate Sensitivity (ECS) of 0.6°C",,"Chris Brierley Senior Lecturer, University College London: I consider this claim to be incorrect and unsubstantiated. The authors are right in stating that “The uptake of machine learning, and specifically ANNs, in climate science has generally been slow compared to many other fields.” The assertion that “This may in part be due to the heavy investment in physical models, particularly GCMs.” is not right though—rather it arises from a widespread acknowledgment within the discipline of meteorology that physically-based models have greater predictive power than purely statistical ones (which is why all weather forecasters use general circulation models). The authors here clearly know that humans have increased CO2 levels and that would be expected to alter the energy budget of the climate. There are certain situations where the statistical assumptions going into the sort of Artificial Neural Network built by the authors are just not met. The introduction of a new factor (us and our emissions) not present in the training data (the climate proxy record) is clearly one such situation. Rather than using their data to claim that recent global warming was natural, it would instead be more appropriate to say that detecting the signal of anthropogenic climate change is hard given the noise of natural variability, especially at local scales. This topic is often referred to as the “emergence” of the climate signal. Ed Hawkins has a nice blogpost on it here. In the maps on that webpage, it shows that climate change (the signal) would not have emerged from natural variations (the noise) until after the end of the proxy records used by Abbot & Marohasy. I would also have expected the authors to have performed an actual calculation of Equilibrium Climate Sensitivity. They appear to assume (a) the climate system responds instantaneously, (b) CO2 levels have been 100 ppm higher throughout the past 150 years – instead of rising roughly exponentially (c) humans did not impact the climate in other ways—e.g. aerosol emissions, other greenhouse gases, and land use change. All those assumptions are not valid. Patrick Brown Assistant Professor, San Jose State University: 1) We know the basic physics of global temperature so it’s incorrect to assume global temperatures follow “natural cycle” sine curves. Temperature is essentially a measure of energy and global temperature changes when an energy imbalance is imposed on the Earth system. This known physics helps us understand global climate changes of the past. The Abbot and Marohasy paper acts as if we don’t know this physics and must rely on curve-fitting (signal analysis) to understand temperature changes. Abbot and Marohasy’s method assumes that temperature changes over centuries move up and down in accordance with sine-curves, with no physical explanation for why temperatures should do that. Earth’s temperature does not know what a sine curve is and there is no reason to think that Earth’s temperature should follow magic “natural cycle” sine-curves. To be more specific, we know that a large portion of the cooling during the Little Ice Age was caused by negative radiative-forcing from volcanic eruptions: Figure – Composite temperature reconstructions with climate forcings and previous hemisphere-scale reconstructions. Vertical red bands indicate volcanic-solar downturns that explain a large portion of the cooling during the “Little Ice Age”.Source:Pages 2K (2013) So temperatures went down, not because they were following some magic “natural cycle” sine-curve but because they were pushed downward from Earth experiencing a negative energy imbalance due to volcanic aerosols. Since the current climate change is also being caused by an energy imbalance, scientists can use this information from the past to assess precisely how sensitive temperature is to energy imbalances. So climate changes of the past do not in any way undermine the attribution of current climate change to anthropogenic greenhouse gasses. The bottom line is that assuming temperature changes blindly follow mathematical functions like sine curves, without considering the known physical reasons for why temperatures change, is scientific nonsense. 2) Their ‘natural cycle’ statistical model cannot predict the recent spike in temperatures. As Gavin Schmidt has pointed out (illustrated here), Abbot and Marohasy mistakenly think that the year 1965 is actually the year 2000. This totally undermines their central claim that their statistical model, based on assumed “natural cycle” sine-curves, can explain recent warming. Shaun Lovejoy Professor, McGill University: It is highly significant for this study that all of the six proxies chosen had proxy temperatures that declined or were at best constant after 1975, underscoring a combination of proxy problems (e.g. dendrochronology) and the unrepresentativeness of the proxy choices. In the “Northern Hemisphere composite” (from [one] Icelandic lake), the temperature even decreases by a whopping 0.3 °C since 1980—yet from the authors’ description, one could be forgiven for thinking that this behaviour was somehow representative of the actual Northern Hemisphere temperature. Rather than using the original data, the authors scanned the published graphs and used very low resolution versions of the data. From their graphs, it would seem that the resolutions they obtain are between 20 – 50 years (more on this later). This is a shame since in many cases the original data had annual resolution. These geographic and temporal resolution issues are underlined since they turn out to be fundamental. For example, a dozen or so globally or hemispherically representative pre-industrial multiproxies exist, each based on hundreds or thousands of individual proxies—not just 6. They show that the pre-industrial global temperature series has decadal scale oscillations that are close to ±0.1 °C and this is supported by pre-1900 instrumental data. The true decadal global scale fluctuations are thus about ten times smaller than the local series analyzed by Abbot and Marohasy. The most important point is that they committed the common but fundamental error of scale, in time, but here, mostly in space. As the authors themselves comment on multiple occasions, on multidecadal time scales the proxy temperatures fluctuate about ±1 °C. This is normal since each proxy only represents the behavior of a tiny region. When the IPCC claims that the industrial epoch temperature has increased by about 1 °C, they are referring to the globally averaged surface air temperature, and this (as we have mentioned) varies only by about ±0.1 °C over decadal time scales. The authors—being apparently unfamiliar with climate science—seem to have missed the factor of 10 discrepancy. And the explanation for the difference is simple. In the pre-industrial epoch, local temperatures varied by ±1 °C over decadal scales, but the variations over different parts of the world tended to cancel out, hence the far lower global variability. However—and this can indeed be seen by careful superposition, even of the authors’ hand picked proxies—in the last century there is a tendency for the local fluctuations to fluctuate together (and upwards!) rather than tending to cancel each other out. That’s the essence of global warming—it’s not local, it’s global! [Read more]"
https://science.feedback.org/review/climate-change-likely-helped-increase-hurricane-harveys-rainfall-early-say-exactly-much/,Mostly correct,"The Atlantic, Robinson Meyer, 2017-08-27",[climate scientists] say that aspects of the case of Hurricane Harvey suggest global warming is making a bad situation worse.,,"Correct but...: Warming sea surface temperatures provide more energy for tropical cyclones and a warmer atmosphere holds more water vapor. While rainfall do show a relationship to climate change, Hurricanes' impact are also influenced by other factors –like blocking events, vertical wind shear, urban planning…– that are not or not easily connected to climate change.","Extreme rain events, including those accompanying Tropical Cyclones, are intensifying as the world warms. However, a dedicated study would be needed to quantify how much more rain Hurricane Harvey generated due to climate change.",[climate scientists] say that aspects of the case of Hurricane Harvey—and the recent history of tropical cyclones worldwide—suggest global warming is making a bad situation worse.,,"Andrew King Research fellow, University of Melbourne: This is a reasonable statement. As tropical cyclones are such complex events— the confluence of many factors coming together—it is difficult to estimate the climate change role in such events. However, it is likely that human-caused climate change has worsened aspects of this event as described later in the article. Dan Chavas Assistant Professor, Purdue University: It is true that for a Harvey-like event—a storm at this location in East Texas that is nearly stationary—global warming likely increases the total rainfall. But we do not know whether global warming makes it more likely for a Harvey-like events to occur in the first place. Risk combines both of these probabilities. In combination, then, it is difficult to say whether there is a climate change effect on this type of flood risk. A number of articles that quote scientists—or were written by scientists—have been published on this topic already. Here are some of the statements published elsewhere that explain the effect of climate change and other factors on the severity of the damage done by Harvey.1) On sea surface temperatures and the effect of warmer atmosphere on moisture content and rain Michael Mann Professor of Meteorology, PennState University: [S]ea surface temperatures in the region have risen about 0.5 °C (close to 1 °F) over the past few decades from roughly 30 °C (86 °F) to 30.5 °C (87 °F), which contributed to the very warm sea surface temperatures (30.5-31 °C, or 87-88 °F). There is a simple thermodynamic relationship known as the Clausius-Clapeyron equation that tells us there is a roughly 3% increase in average atmospheric moisture content for each 0.5 °C of warming. Sea surface temperatures in the area where Harvey intensified were 0.5-1 °C warmer than current-day average temperatures, which translates to 1-1.5 °C warmer than “average” temperatures a few decades ago. That means 3-5% more moisture in the atmosphere. (Source) Adam Sobel Professor, Columbia University: [T]he recurrence of 100- and 500-year floods every few years is unlikely to be entirely accidental. Though Houston developers, many state and local officials, and the occupant of the White House don’t want to hear it, it’s likely that human-induced climate change has played a role in the increasing frequency of these events. There is more water vapor in a warmer atmosphere, and many other extreme rainfall events both nationwide and worldwide (including, very nearby, the Louisiana flood of just a year ago) have been shown to be amplified as a consequence. (Source) Andrew King Research fellow, University of Melbourne: While it’s hard to pin the blame for Hurricane Harvey directly on climate change, we can say this: human-caused climate change has enhanced some of the impacts of the storm. We know that climate change is enhancing extreme rainfall. As the atmosphere is getting warmer it can hold more moisture (roughly 7% more for every 1°C rise in temperature). This means that when we get the right circumstances for very extreme rainfall to occur, climate change is likely to make these events even worse than they would have been otherwise. Without a full analysis it is hard to put exact numbers on this effect, but on a basic level, wetter skies mean more intense rain. (Source) Suzana Camargo,Professor, Columbia University: and Adam SobelProfessor, Columbia University Tropical cyclones are similar to other truly heavy rain events in that they are very efficient in turning that water vapor into rain. While there is much uncertainty about how tropical cyclones should change with global warming, that they should produce more rain is perhaps one of the most confident predictions of current science on this topic. The only debate is how much heavier the rains should get with each degree of warming, and to what extent this effect is already present in observed storms today. (Source) 2) On the high pressure system that kept Harvey in place Michael Mann Professor of Meteorology, PennState University: [P]art of what has made Harvey such a devastating storm is the way it has stalled right near the coast, continuing to pummel Houston and surrounding regions with a seemingly endless deluge which will likely top out at nearly 4 feet of rainfall over a several days-long period before it is done. The stalling is due to very weak prevailing winds which are failing to steer the storm off to sea, allowing it to spin around and wobble back and forth like a top with no direction. This pattern, in turn, is associated with a greatly expanded subtropical high pressure system over much of the U.S. right now, with the jet stream pushed well to the north. This pattern of subtropical expansion is predicted in model simulations of human-caused climate change. (Source) Suzana Camargo,Professor, Columbia University: and Adam SobelProfessor, Columbia University In this case, one of the most important causes of the disaster is Harvey’s slow motion. That in turn is a consequence of the specific weather situation, in which the storm is caught between two high-pressure systems and the jet stream is too far away to the north to pull it away. In other words, it has just been sitting and dumping its huge quantities of rain in the same area for days, rather than spreading it out over a long track as a typical storm would. There are some ideas in the scientific literature that suggest that global warming may make this situation more probable. However, these ideas are still speculative and not widely agreed upon by scientists. (Source) Friederike Otto Deputy Director Environmental Change Institute, University of Oxford: It is very appropriate to highlight that this is the kind of event we expect to see more of in a warming world. However, to apply this argument directly and attribute (and quantify) the impacts from Harvey itself to human-induced climate change, neglects that climate change is not just about warming. In a changing climate, two effects come together: not only does the atmosphere warm up (thermodynamic effect) but the atmospheric circulation, which determine where, when, and how weather systems develop, can change as well (dynamic effect). Changes in the atmospheric circulation can increase the thermodynamic effect (as we saw during floods Louisiana in 2016) or act in the opposite direction to the thermodynamic effect, leading to locally decreasing the risk of extreme rainfall or canceling the effect of the warming alone (examples here). Hence, while it is very likely that climate changes played a role in the intensity of the rainfall, it is far from straightforward in practice to quantify this role. […]If we thus want to know whether Harvey is a “harbinger” for the future of Houston, the attribution question addressing the overall likelihood of a hurricane like Harvey to occur, which includes many variables other than temperature and sea level rise that interact, needs to be answered by carefully estimating the likelihood of such hurricanes developing in a warming world as well as how much rain they bring. It is a question scientists now can answer, but it requires a dedicated study. Furthermore, attributing the flooding and damages to climate change add more complexity. The answer does not depend on the weather alone but on the land surface, local hydrology, management, … and ultimately who and what is in harm’s way. (Source) Tim Palmer, Professor, University of Oxford: What has made Harvey so disastrous for Texas is the fact that it has stalled and the circulation patterns are continuously feeding moist air from the Gulf of Mexico up over Texas. So perhaps the single most important question for attributing Harvey to climate change is whether such stationary hurricanes will become more commonplace in the future. This is a question about possible changes in circulation and hence dynamics, rather than changes in the moistness and warmth of the air per se and hence thermodynamics. Unfortunately it is not a question that can be answered with a great deal of confidence from current-generation global climate models since their spatial resolution is typically inadequate to address such regional matters with any degree of reliability. (Source) 3) On the human factors that help determine the damage caused a particular storm Ilan Kelman, University College London: The hurricane is just a storm, it is not the disaster. The disaster is the fact that Houston population has increased by 40% since 1990. The disaster is the fact that many people were too poor to afford insurance or evacuate. Climate change did not make people build along a vulnerable coastline so the disaster itself is our choice and is not linked to climate change. (Source) Suzana Camargo,Professor, Columbia University: and Adam SobelProfessor, Columbia University [G]iven a metro area of 6.5 million people that basically sits in a paved floodplain, crossed by bayous, creeks, and rivers, and the same meteorological situation, we would be seeing a very major disaster even without any human influence on climate. But any extra rainfall due to warming just increases the human and financial toll of the disaster. (Source) Andrew King Research fellow, University of Melbourne: There are other factors that are making this storm worse than others in terms of its impact. Houston is the second-fastest growing city in the US, and the fourth most populous overall. As the region’s population grows, more and more of southern Texas is being paved with impermeable surfaces. This means that when there is extreme rainfall the water takes longer to drain away, prolonging and intensifying the floods. Hurricane Harvey is likely to end up being one of the most costly disasters in US history. It is also likely that climate change and population growth in the region have worsened the effects of this major storm. (Source)"
https://science.feedback.org/review/atlantic-accurately-explores-climate-context-tropical-storm-harvey-robinson-meyer/,1.5,"The Atlantic, by Robinson Meyer, on 2017-08-27.",,"""Did Climate Change Intensify Hurricane Harvey?""",,,,,"This article in The Atlantic attempted to investigate what can be said about the relationship between Tropical Storm Harvey and climate change. Harvey’s record rainfall totals around Houston, Texas are partly the result of how long it has persisted in the same location, making it an unusual storm. Scientists who reviewed the article indicated that it provides an accurate summary of how tropical cyclones are expected to change due to global warming, as well as what aspects of Harvey do not have clearly understood relationships with climate change.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Andrew King Research fellow, University of Melbourne: This article provides an excellent overview of Hurricane Harvey with good explanations of why it’s so extreme and how climate change may have contributed to this event. Karthik Balaguru Scientist, Pacific Northwest National Laboratory: Overall I think it’s a well written article that captures the essence of our understanding that under climate change storms will likely bring more rainfall. In the case of Harvey, all we can say is that it is consistent with those ideas. But we cannot say that it is the direct consequence of climate change. Dan Chavas Assistant Professor, Purdue University: One must be careful not to assume that warmer waters automatically make all aspects of extreme weather worse. Though for a given storm we do expect rainfall rates to increase at a warmer sea surface temperature, how storm size, regional counts, and track characteristics (e.g. the likelihood that a storm will become nearly stationary as was the case with Harvey) will change in a warmer world are much less well understood. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from the article; comments and replies are from the reviewers. Tropical cyclones and extreme rain events are expected to intensify as the world warms, but the complex meteorological conditions that produced Harvey also depend on processes with an uncertain relationship to climate change. “But [climate scientists] say that aspects of the case of Hurricane Harvey—and the recent history of tropical cyclones worldwide—suggest global warming is making a bad situation worse.” Andrew King Research fellow, University of Melbourne: This is a reasonable statement. As tropical cyclones are such complex events— the confluence of many factors coming together—it is difficult to estimate the climate change role in such events. However, it is likely that human-caused climate change has worsened aspects of this event as described later in the article. Dan Chavas Assistant Professor, Purdue University: It is true that for a Harvey-like event—a storm at this location in East Texas that is nearly stationary—global warming likely increases the total rainfall. But we do not know whether global warming makes it more likely for a Harvey-like events to occur in the first place. Risk combines both of these probabilities. In combination, then, it is difficult to say whether there is a climate change effect on this type of flood risk. For more details on what can be said about the influence of climate change on Hurricane Harvey, read this claim review post. “The human contribution can be up to 30 percent or so of the total rainfall coming out of the storm” Karthik Balaguru Scientist, Pacific Northwest National Laboratory: Climate change doesn’t cause events like this, but probably makes them worse by making storms (which are strong to begin with) more intense and enhancing rainfall in that process. I don’t think anyone can say with confidence that climate change has made tropical cyclones worse. There’s too much natural variability (Pacific Decadal Oscillation, Atlantic Multidecadal Oscillation, etc.) and the sample size of intense hurricanes is small. It is consistent with what’s predicted for the future, though. However, I’m not exactly sure where the “30 percent” number comes from for the human contribution to rainfall. For every one degree increase in sea surface temperature, the saturation vapor pressure increases by about 7% based on the “Clausius-Clapeyron” equation. There’s also an assumption that hurricanes will likely get stronger because of climate change, so perhaps the stronger winds will also increase evaporation. Andrew King Research fellow, University of Melbourne: A reference here would have been useful as it’s unclear exactly where this number comes from. We know that human-caused climate change can increase both the moisture content of the atmosphere, as described by the Clausius-Clapeyron relation, and the energetics of the storm, as there is increased latent heat release. Both of these climate change-influenced drivers have the potential to cause increased precipitation. Dan Chavas Assistant Professor, Purdue University: Again, it is true that in a warmer world we expect the rain rate to increase significantly. (I am not sure about the 30% specifically, but that doesn’t matter.) Thus, given the existence of a Harvey-like storm—a storm at this location in East Texas that is nearly stationary—global warming likely significantly increases the total rainfall. However, there is a second probability to account for: how likely is it for a Harvey-like event to occur in the first place? This is a much more difficult probability to assess and we do not know how climate change affects it. Risk combines these two probabilities. As a result, it is difficult to say whether there is a climate change effect on the likelihood of a flood event of this magnitude. “The tropical storm, feeding off this unusual warmth, was able to progress from a tropical depression to a category-four hurricane in roughly 48 hours.” Andrew King Research fellow, University of Melbourne: This storm was quite remarkable in its intensification. It does seem likely that the warmth of the surface and sub-surface waters, primarily linked to variability but also with a small climate change contribution, enhanced the storm."
https://science.feedback.org/review/new-york-times-accurately-assesses-the-state-of-alaskan-permafrost-henry-fountain/,1.6,"The New York Times, by Henry Fountain, on 2017-08-23.",,"""Alaska's Permafrost is Thawing""",,,,,"This story in the New York Times looks at the thawing trend of permafrost (permanently frozen soil and sediment) in Alaska as the region warms due to climate change, and the potential for this landscape to be an additional source of greenhouse gases in the future, which would further amplify global warming. Scientists who reviewed the article found that it accurately represented current research on the region, which shows that Alaska’s area of permafrost is shrinking as more and more ground thaws. This destabilizes the land surface, damaging buildings and infrastructure, and allows frozen organic matter to decay. Given the uncertainty in future projections of greenhouse gases released by thawing permafrost, however, providing more information than just the upper end of the range could help readers understand this feedback more clearly. This is part of a series of reviews of 2017’s most popular climate stories on social media.GUEST COMMENTS: Miriam Jones, Research Geologist, United States Geological Survey: This article accurately represents the state of our knowledge on permafrost thaw and carbon dynamics, and it conveys why this is an important issue to study for the future state of our planet. I take slight issue with the description of the age of the permafrost (“centuries”); the author could have gone bolder and said centuries to many millennia, since permafrost carbon age can range from a few centuries to as old or older than the last glacial maximum (20,000 years ago). Permafrost thaw is described as gradual and “top down”, which is definitely true, but it’s not the only way it thaws. It can thaw laterally, from below, and much faster than gradually.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Ben Poulter Research Scientist, NASA: The observations being made by Woods Hole Research Center researchers on the thawing of permafrost is consistent with other ecosystem changes taking place in the region that are related to climate change. These include increased growing season length, decreasing arctic sea ice, disruptions to infrastructure, and changes in wildlife populations. The main uncertainty (which this work contributes to reducing) is related to how strong the permafrost-climate feedback is, and how continued climate change will destabilize the high-arctic frozen soils. Andrew MacDougall Assistant Professor, St. Francis Xavier University: Overall the article does a good job of summarizing the potential effects of the permafrost carbon feedback to climate change. However, the article highlights the very upper-end of the estimated strength of the feedback instead of giving the most likely values or ranges. Figure – Simulated warming contribution from permafrost carbon feedback for 4 scenarios of future human greenhouse gas emissions. SourceMacDougall et al (2012) MacDougall et al (2012) Significant contribution to climate warming from the permafrost carbon feedback, Nature Geoscience Charles Koven Staff Scientist, Lawrence Berkeley National Lab: The article is accurate in its descriptions of the physical and ecological processes that are behind permafrost changes. It also does a good job of getting across the nature of the work of actual scientists working in the field, what they are doing and why they are doing it. Jeff Chanton Professor, Florida State University: I work in this field, and I think they have it right. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time."
https://science.feedback.org/review/extreme-weather-events-clearly-becoming-common-contrast-lord-lawsons-claim/,Inaccurate,"BBC, Nigel Lawson, 2017-08-10","The IPCC, the Intergovernmental Panel on Climate Change, which is sort of the voice of the consensus, concedes that there has been no increase in extreme weather events.",,"Misrepresents source: The 2013 IPCC report identifies some extreme events for which trends are unclear, but it also identifies certain types of weather extremes that research shows are clearly increasing, like heat waves and intense rainfall.","Globally, there has been a clear increase in certain weather extremes including heat waves and intense rainfall events.","[Al Gore] said that there had been a growing increase, which had been continuing, in the extreme weather events. There hasn’t been. All the experts say there haven’t been. The IPCC, the Intergovernmental Panel on Climate Change, which is sort of the voice of the consensus, concedes that there has been no increase in extreme weather events. Extreme weather events have always happened. They come and go. And some kinds of extreme weather events of a particular time increase, whereas others, like tropical storms, diminish…",,"Andreas Prein Project Scientist, National Center for Atmospheric Research: This is a false statement since the IPCC AR5 even states in its summary for policy makers that “Human influence has been detected … in changes in some climate extremes”. In this report it is also stated that: “It is now very likely that human influence has contributed to observed global scale changes in the frequency and intensity of daily temperature extremes since the mid-20th century, and likely that human influence has more than doubled the probability of occurrence of heat waves in some locations” and “It is virtually certain that there will be more frequent hot and fewer cold temperature extremes over most land areas on daily and seasonal timescales as global mean temperatures increase. It is very likely that heat waves will occur with a higher frequency and duration.” Since the publication of the IPCC AR5 many studies where published on the detection and attribution of man made impacts on climate extremes. An example which shows the human influence on precipitation extremes is Fischer and Knutti (2015)*. Fischer and Knutti (2015) Anthropogenic contribution to global occurrence of heavy-precipitation and high-temperature extremes, Nature Climate Change Ken Caldeira Senior Scientist, Carnegie Institution for Science: A good place to go for IPCC conclusions related to extreme events is the Summary: for Policy Makers of the 2012 IPCC “SREX”1 and 2014 Synthesis reports2. The 2014 Synthesis Report concludes: “Changes in many extreme weather and climate events have been observed since about 1950. Some of these changes have been linked to human influences, including a decrease in cold temperature extremes, an increase in warm temperature extremes, an increase in extreme high sea levels and an increase in the number of heavy precipitation events in a number of regions…. It is very likely that the number of cold days and nights has decreased and the number of warm days and nights has increased on the global scale. It is likely that the frequency of heat waves has increased in large parts of Europe, Asia and Australia. It is very likely that human influence has contributed to the observed global scale changes in the frequency and intensity of daily temperature extremes since the mid-20th century. It is likely that human influence has more than doubled the probability of occurrence of heat waves in some locations.” Thus, Lord Lawson’s statement is false. On the other hand, in the Synthesis Report, the IPCC also states: “There is low confidence that anthropogenic climate change has affected the frequency and magnitude of fluvial floods on a global scale. … There is low confidence in observed global-scale trends in droughts, due to lack of direct observations, dependencies of inferred trends on the choice of the definition for drought, and due to geographical inconsistencies in drought trends. … There is low confidence that long-term changes in tropical cyclone activity are robust, and there is low confidence in the attribution of global changes to any particular cause. However, it is virtually certain that intense tropical cyclone activity has increased in the North Atlantic since 1970.” Thus, there are many extreme events occurring which likely bear little or no relationship to climate change, and this may be what Lord Lawson was attempting to point out. While true, this does not mean that climate change is not contributing to increases in some kinds of extreme events. 1- IPCC (2012) Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation 2- IPCC (2014) Climate Change 2014: Synthesis Report Jeremy Fyke Postdoctoral researcher, Los Alamos National Laboratory: Lord Lawson’s blanket claim that the frequency of extreme events has not increased is wrong. Due to overall warming, for example, it is very clear in observations that the frequency and severity of extreme heat events is increasing, and that this increase would not occur in the absence of anthropogenic forcing. Twila Moon Research Scientist, University of Colorado, Boulder: This statement is not true. The IPCC issued a 2012 report on “Managing the risks of extreme events and disasters to advance climate change adaptation”1. Even within the Summary for Policymakers, the report lists the evidence of changes in extreme weather and climate events. Changes are different depending on the location (e.g. more intense and longer droughts in southern Europe and West Africa, while this is not true in North American and northwestern Australia), but changes in extremes have been documented across the globe (with low to high confidence depending on the type of event and location). The IPCC AR5 Summary for Policymakers2 states: “Changes in many extreme weather and climate events have been observed since about 1950 (see Table SPM.1 for details). It is very likely that the number of cold days and nights has decreased and the number of warm days and nights has increased on the global scale. It is likely that the frequency of heat waves has increased in large parts of Europe, Asia and Australia. There are likely more land regions where the number of heavy precipitation events has increased than where it has decreased. The frequency or intensity of heavy precipitation events has likely increased in North America and Europe. In other continents, confidence in changes in heavy precipitation events is at most medium.” It also notes: “There has been further strengthening of the evidence for human influence on temperature extremes since the SREX. It is now very likely that human influence has contributed to observed global scale changes in the frequency and intensity of daily temperature extremes since the mid-20th century, and likely that human influence has more than doubled the probability of occurrence of heat waves in some locations.” Note that it’s possible to cherry pick types of extreme events and locations to argue that there is no evidence. Also, perhaps even more important than whether extremes have already changed is that there is high certainty of changes in a number of important extremes over the coming decades. 1- IPCC (2012) Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation 2- IPCC (2013) Climate Change 2013: The Physical Science Basis Adam Sobel Professor, Columbia University: The statement, though often repeated, is patently false. Clear increases have been documented in the frequencies and intensities of heat waves and extreme precipitation events. There are other kinds of events for which there are no trends, and then others for which it is not clear whether there are trends, because natural variability is difficult to separate from long-term trends in short historical records. And indeed predictions about what global warming should do to extreme events vary from one kind of event to the next. But the observed increases in heat waves and extreme rain events are right in line with what is expected based on the predictions. And, because of the confounding effect of natural variability, there are some changes that we shouldn’t expect to see clearly yet, even though we are pretty confident that we will eventually. These include increasing intensity of tropical cyclones, and increasing occurrence of hydrological droughts and wildfires in many places. Daniel Swain Climate Scientist, University of California, Los Angeles: The specific claim here–that the IPCC scientific reviews find no increase in extremes–is incorrect, as is the broader implication that there is no observational evidence for increasing meteorological extremes. The IPCC Special Report on Managing the Risk of Extreme Events (SREX) directly contradicts the former claim, while a rapidly growing body of scientific research points toward a clear increase in certain types of extreme weather events–especially heat waves, droughts, and heavy downpours (e.g., Diffenbaugh et al. 2017)*. While it is certainly true that some of these extreme events would have occurred naturally (and that not all event types are increasing in all regions), human-caused global warming is exerting an increasingly substantial influence on the risk of global temperature and precipitation extremes. Diffenbaugh et al. (2017)Quantifying the influence of global warming on unprecedented extreme climate events.Proceedings of the National Academy of Sciences Ed Hawkins Principal Research Fellow, National Centre for Atmospheric Science: The statement about the IPCC is incorrect. The 5th Assessment Report of the IPCC actually states in the Summary for Policymakers that: “Changes in many extreme weather and climate events have been observed since about 1950.” It goes on to give specific examples: “It is very likely that the number of cold days and nights has decreased and the number of warm days and nights has increased on the global scale. It is likely that the frequency of heat waves has increased in large parts of Europe, Asia and Australia. There are likely more land regions where the number of heavy precipitation events has increased than where it has decreased. The frequency or intensity of heavy precipitation events has likely increased in North America and Europe.” The statement that “extreme weather events have always happened” is misleading. Yes, extreme weather events have always happened, but many of them show long-term trends in frequency and/or intensity, as the IPCC AR5 states. For other types of extreme event we would not have expected to clearly see a long-term change given the warming to date, but would expect to see significant changes at higher warming levels. Richard Betts Professor, Met Office Hadley Centre & University of Exeter: This statement is not true. The IPCC does not say that “there has been no increase in extreme weather events”. In the IPCC’s Fifth Assessment Report, in the Physical Science volume, the very first table of the summary document gives a comprehensive, careful and nuanced assessment of different types of extreme weather events and whether there has been an increase in them. The IPCC’s conclusion is that for some types of extreme weather event, such as hot days, heatwaves and heavy precipitation, there have been increases (with varying levels of confidence and likelihood attached to these conclusions, ranging from “very likely” to “medium confidence. For other types of extreme weather events, such as drought and tropical cyclones, there is low confidence in a global-scale trend but nevertheless increases in some more localized regions are likely to have occurred. Andrew King Research fellow, University of Melbourne: Using the vague term “extreme weather”, Lord Lawson argues there has been no increase in such events. He then makes a specific reference to tropical storms for which it is true that while we are seeing signs of change in some characteristics we are not seeing an increase in their overall number. However, if we look at other types of extreme weather that cause greater numbers of fatalities, such as heatwaves, then Lord Lawson is incorrect. Heatwaves impact human health[1], and can compound the effects of drought and famine. The intensity, frequency and duration of heatwaves around the world is on the rise due to human-caused climate change[2]. Figure – Warm spell and heatwave trends in the number of days participating in an event, in which conditions persist for at least three consecutive days. Trends are for the period 1950–2011. Units are percentage of days per season/decade. Hatching represents where trends are significant at the 5% level, and grey indicates areas where there are insufficient observations for this study. Source:Perkins et al (2012) 1- Perkins et al (2012)Increasing frequency, intensity and duration of observed global heatwaves and warm spells. Geophysical Research Letters 2- Mitchell et al (2016) Attributing human mortality during extreme heat waves to anthropogenic climate change.Environmental Research Letters"
https://science.feedback.org/review/lord-lawson-falsely-claims-global-temperatures-declined-last-decade/,Inaccurate,"BBC, Nigel Lawson, 2017-08-10","according, again, to the official figures—during this past 10 years, if anything, mean global temperature, average world temperature, has slightly declined",,Factually inaccurate: Global temperature datasets show rising—not falling—temperatures over the last ten years.,"Global temperature has continued to rise during the last decade. The three warmest years on record are 2014, 2015, and 2016.","And as for the temperature itself, it is striking, [Gore] made his previous film 10 years ago and—according, again, to the official figures—during this past 10 years, if anything, mean global temperature, average world temperature, has slightly declined.",,"UPDATE (18 Aug 2017): The Global Warming Policy Forum, of which Lord Lawson is the chairman, tweeted that Lord Lawson’s statement was based on a chart that is “erroneous”. Read more Andreas Prein Project Scientist, National Center for Atmospheric Research: I am wondering which official figures Lord Lawson speaks about since the year with the hottest global mean temperature is currently 2016, the second hottest is 2015, and third is 2014 according to data sets from NASA, the Climatic Research Unit, and the National Oceanic and Atmospheric Administration. In fact, according to these data sets the last 10 years saw some of the most rapid global mean temperature increases in observed history. Below is a figure that shows the data from NASA. Ken Caldeira Senior Scientist, Carnegie Institution for Science: Multiple independent analyses have concluded that years 2014, 2015 and 2016 were the hottest annual global mean temperatures ever observed by modern humans. It would be mathematically impossible for the hottest years to appear at the end of 10 years of declining temperature. An example of such temperature records is available here. It is obvious and clearly demonstrable that this statement made by Lord Lawson is false. Jeremy Fyke Postdoctoral researcher, Los Alamos National Laboratory: This claim is false and not supported by any official figures. Average world temperature reached a record high in 2016. Twila Moon Research Scientist, University of Colorado, Boulder: It’s not clear why Nigel Lawson would think that he should only mention 10 years of global temperature data. We are now able to look at trends that are much longer than 10 years. In fact, when looking at climate trends it is especially useful to look at 20+ year records. Many different groups are studying global temperature and there is a clear consensus that the Earth has been warming over the last several decades. It is critical to remember that short-term fluctuations in the record are expected, but do not negate the long-term march of increasing global temperatures. This is true regardless of the trend over the last 10 years. Furthermore, the scientific evidence actually points towards warmer temperatures over the last decade*. NASA keeps a nice up-to-date global temperature graph in it’s Vital Signs. Rahmstorf et al (2017) Global temperature evolution: recent trends and some pitfalls, Environmental Research Letters Victor Venema Scientist, University of Bonn, Germany: It would be hard to be more wrong. The graph below shows the “official” figures. Source: Climate.gov MetOffice statistician Doug McNeal kindly made a figure to show the last 10 years more clearly. Source Ten years is very short to judge whether the climate is changing. But in the figure you can see that the three hottest years on record occurred in 2014, 2015 and 2016. 2017 is on track to be among the hottest again. Source Adam Sobel Professor, Columbia University: The statement about the last 10 years is patently false. Each of the the last three years—2014, 2015, and 2016—has been the warmest in history. It might have been true, in a narrow sense, if it had been made a few years ago; but even then it would have been highly misleading, since the predictions about global warming apply to long-term averages, not individual decades. Each decade since the mid-20th century has been warmer than the one before, without exception. Ed Hawkins Principal Research Fellow, National Centre for Atmospheric Science: This statement by Lord Lawson is entirely untrue. Over the last 10 years, every surface global temperature dataset shows a clear rise in temperatures with 2014, 2015 & 2016 being the warmest years on record. The latest estimates of global atmospheric temperature, as measured by satellites, also show a warming trend over the past 10 years. Richard Betts Professor, Met Office Hadley Centre & University of Exeter: This statement is not true. The official figures do not show that the global mean temperature “has slightly declined”. In fact they show the opposite – global mean temperature has increased during the past 10 years. The last 3 years were warmer than the previous 7 and indeed were the warmest in record, and this year is also shaping up to be nearly as warm (probably not quite as warm as last year since the influence of the El Nino has passed, but still a very warm year). This is very clearly seen in the Met Office dataset, which happens to be shown prominently on the websites for Lord Lawson’s organisations, the Global Warming Policy Foundation and the Global Warming Policy Forum – so his claim is contradicted by information that headlines his own websites. UPDATE (18 Aug 2017): Here is a screenshot of the statement posted on the Global Warming Policy Forum’s Twitter account:"
https://science.feedback.org/review/forbes-article-accurately-describes-research-atlantic-ocean-circulation-weakening-headline-goes-farther-trevor-nace/,1,"Forbes, by Trevor Nace, on 2017-08-03.",,"""Global Ocean Circulation Appears To Be Collapsing Due To A Warming Planet""",,,,,"This article at Forbes describes a study on the possible influence of Arctic sea ice loss on recent changes to a key portion of ocean circulation in the Atlantic Ocean. This Atlantic Meridional Overturning Circulation (AMOC) transports heat around the North Atlantic, but could be slowing down as a result of climate change, with consequences for regional temperatures in Europe and eastern North America. Scientists who reviewed the article found that it accurately summarized research on the topic of the AMOC. However, the headline used stronger wording than the article, stating that “global ocean circulation appears to be collapsing due to a warming planet”. That is misleading, as this research is analyzing a weakening of the circulation pattern, but not something as extreme as a “collapse”.See all the scientists’ annotations in context If the link does not work due to Forbes’ landing page, addHypothesisto your browser and switch it on when the article pagehas loaded. This is part of a series of reviews of 2017’s most popular climate stories on social media.GUEST COMMENTS: Stefan Rahmstorf Professor, Potsdam University: I find the article is a very accurate summary of the state of science, with the exception of the word “collapsing” in the headline (which may well have been not the author’s choice). Changing this word to “weakening” would have left me with nothing to complain about.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Dan Jones Physical Oceanographer, British Antarctic Survey: This is an accurate, concise summary of the slowdown of the AMOC and its possible future states. There are a couple of minor issues—specifically, one of the links goes to an irrelevant article, and it would be useful to have a couple more citations to the scientific literature. The title is possibly a little overstated—I might instead say that the AMOC is at risk of collapsing in a warming world. Alek Petty Postdoctoral associate, NASA Goddard Space Flight Center: I think the article did a pretty good job of summarizing the main findings of this paper (and other recent studies on this theme), while adding some appropriate disclaimers. The main issue I had was with the headline. The weakening of the Atlantic Meridional Overturning Circulation isn’t exactly a collapse of the global ocean circulation, and the author makes a point of the high uncertainty that remains regarding the significance of this result towards the end of the story. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Featured Annotations: The statements quoted below are from the article; comments and replies are from the reviewers. “Global Ocean Circulation Appears To Be Collapsing Due To A Warming Planet” Dan Jones Physical Oceanographer, British Antarctic Survey: I’m a little hesitant about the title. The slowdown of the Atlantic Meridional Overturning Circulation is not the same thing as the “collapse of global ocean circulation”. It might be more accurate to say that the AMOC is at risk of collapsing in a warming world. Also, it’s worth noting that although we understand that there is a connection between AMOC and the amount of carbon dioxide in the atmosphere, the mechanisms involved in this connection are still under investigation. “Evidence is growing that the comparatively cold zone within the Northern Atlantic could be due to a slowdown of this global ocean water circulation.” Dan Jones Physical Oceanographer, British Antarctic Survey: For example, this study: Rahmstorf et al (2015) Exceptional twentieth-century slowdown in Atlantic Ocean overturning circulation, Nature Climate Change “While geologists have studied events in the past similar to what appears to be happening today, scientists are largely unsure of what lies ahead.” Stefan Rahmstorf Professor, Potsdam University: A very brief but correct reference to two issues: 1) We know the AMOC has collapsed several times in the past 100,000 years in the so-called Heinrich events, and 2) we cannot predict its future response to greenhouse warming very well because it is a highly non-linear system. “Scientists have long known about the anomalous ‘warming hole‘ in the North Atlantic Ocean, an area immune to warming of Earth’s oceans.” Dan Jones Physical Oceanographer, British Antarctic Survey: This link for “warming hole” appears to go to an irrelevant article. Here are two relevant studies on the “warming hole”: Drijfhout et al (2012) Is a Decline of AMOC Causing the Warming Hole above the North Atlantic in Observed and Modeled Warming Patterns?, Journal of Climate Rahmstorf et al (2015) Exceptional twentieth-century slowdown in Atlantic Ocean overturning circulation, Nature Climate Change"
https://science.feedback.org/review/wall-street-journal-op-ed-economic-consequences-climate-change-found-naive-scientists-david-henderson-john-cochrane/,-1.5,"The Wall Street Journal, by David Henderson, John Cochrane, on 2017-07-30.",,"""Climate Change Isn’t the End of the World""",,,,,"This Wall Street Journal commentary by David Henderson and John Cochrane argues that the world would be better off adapting to climate change than eliminating the greenhouse gas emissions that cause warming. Scientists who reviewed this article found that it does so by ignoring most climate impacts apart from estimates of Gross Domestic Product change, by using only the most optimistic estimates of this economic loss, and by focusing on adaptation possibilities in high-income nations like the United States. Climate change could have a much larger economic impact, along with impacts on the spread of human disease, food security, extreme weather, and marine ecosystems, for example.See all the scientists’ annotations in context REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Aaron Bernstein Associate Director of the Center for Health and the Global Environment, Boston Children’s Hospital, Harvard: Although many claims in this op-ed don’t mesh with reality, the most concerning delusion presented is that the health costs of climate change are both known and manageable. Legitimate economic analyses have put the costs of climate change at 2100 to GDP at several percent to more than 20%[1], with the variability largely due to different discount rates. Simply put, the more you care about children, the more expensive climate change becomes. Even these higher damage estimates may fail to capture the full costs of extreme events over time, as Martin Weitzman’s work has shown. But there’s another, and more difficult, rub. What if we don’t understand the full consequences of greenhouse gas emissions? Consider ocean acidification, which is a direct consequence of higher atmospheric carbon dioxide concentrations. The higher acid content in the world’s oceans has already begun to interfere with marine life, including fish reproduction. Research has just begun to explore the reverberations of ocean acidification to human nutrition (and consequently risk of migration and conflict). Economists do not include these massive externalities in their estimates because they have yet to be quantified. If we underestimate climate damages, we won’t simply have a costly externality kicked down the road for our children to deal with. We might not have a viable planet, and without a second planet in the wings, betting the viability of the world on a few uncertain economic analyses seems like an act of utter folly. We must, of course, make trade-offs in where we put our money but doing so based on the face value of current economic evaluations—especially those based on GDP which is generally regarded as a poor measure of economic health—gives catastrophic error too great a chance. A better approach would be to focus on implementing carbon prices that will limit greenhouse gas emissions to levels that will prevent levels of warming that the scientific community and most nations on earth have deemed potentially disastrous for human civilization. 1- Burke et al (2015)Global non-linear effect of temperature on economic production. Nature David Easterling Chief of the Scientific Services Division, NOAA's National Climatic Data Center: This is a very simplistic, almost naive op-ed on climate change impacts. Some assertions such as the one about CO2 being good for plants demonstrates that the authors do not know or understand how increasing CO2 is good or bad for plants, they are just repeating something they heard. The idea that Miami is going to build a dike like Rotterdam is almost laughable. Of course climate change is not the only risk to society, but it is the biggest environmental risk. And most large buildings (e.g. Empire State Building) are not rebuilt every 50 years, only smaller, more expendable ones are. Frank Vöhringer Dr. rer. pol, Scientist, Ecole Polytechnique Fédérale de Lausanne (EPFL): The article plays down impacts of climate change that most studies consider to be highly important: e.g. the death toll of heat waves, hazards to coastlines, costs and friction of migration and other adaptation. While it is true that climate change is not the only risk our society faces, economic studies suggest that the risks of climate change are important, especially in certain economic segments (e.g. agriculture, health) and for low income countries with low capacity for adaptation. The article fails to mention that hazards and distributive issues of climate change increase all the other risks that the authors itemize, “nuclear explosions, a world war, global pandemics, crop failures and civil chaos”, even if it is not yet clear to what extent. Verena Schoepf Research Associate, University of Amsterdam: The authors seem unaware of many consequences of climate change, particularly related to the ocean. The increase in ocean acidity and temperature, due to uptake of atmospheric CO2, will have tremendous consequences for many marine organisms and thus ultimately humans via sea level rise, impacts on weather and climate, food security, etc. Wolfgang Cramer Professor, Directeur de Recherche, Mediterranean Institute for Biodiversity and Ecology (IMBE): This article argues that policies concerning climate change need to differentiate between different objectives and instruments and also says that, in some sectors such as built infrastructure, adaptation may be less costly than what is conventionally assumed. While this may be true as a general statement (and nothing is new about it), the article creates confusion rather than clarification by focusing only on the few sectors where, in a “North American world” unaware of any poor countries, adaptation can be achieved at manageable cost. The article does not ask the question how other sectors besides the construction sector might fare under significant warming, nor how low-income people (inside or outside North America) would be affected. It also avoids speaking about the major economic and socio-political disruptions of the world being caused by warming and sea-level rise in developing countries. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Featured Annotations: The statements quoted below are from the article; comments and replies are from the reviewers. “Carbon dioxide hurts nobody’s health. It’s good for plants. Climate change need not endanger anyone” Aaron Bernstein Associate Director of the Center for Health and the Global Environment, Boston Children’s Hospital, Harvard: By this logic, the authors would gladly drink water endlessly, in the belief that as a harmless—even potentially beneficial—substance, doing so could never hurt them. Unfortunately for them they’d die from having so wrecked their bodies’ chemistry. Carbon dioxide, like water, isn’t acutely toxic to people (though it does appear to slow our brains down). But the amount of carbon dioxide in the atmosphere is already 50% higher than at any point in modern human existence. The harms that result from this change to the planets chemistry are many and well described in, among other places, the U.S. National Climate Assessment. “Healthy societies do not fall apart over slow, widely predicted, relatively small economic adjustments of the sort painted by climate analysis. Societies do fall apart from war, disease or chaos. Climate policy must compete with other long-term threats for always-scarce resources.” Aaron Bernstein Associate Director of the Center for Health and the Global Environment, Boston Children’s Hospital, Harvard: To suggest that climate change does not bear (or has little bearing) upon war, disease, and chaos represents either an exceedingly narrow and optimistic view of available peer reviewed research on the influence of climate change on these outcomes or ignorance. The extraordinary threat that climate change already poses to national security was outlined by the U.S. Defense Department in 2015. Research on climate change and infectious disease risks suggests that it either directly (through changes in mosquito population distributions) or indirectly (through forcing mass migrations) will augment risks of pandemics."
https://science.feedback.org/review/2017-track-among-hottest-year-recorded-scientists-not-surprised-thinkprogress-article-suggests-joe-romm/,1,"Think Progress, by Joe Romm, on 2017-07-19.",,"""2017 is so unexpectedly warm it is freaking out climate scientists""",,,,,"ThinkProgress published a brief but influential article commenting on record warm global temperature over the first half of 2017. The scientists who have reviewed the article confirm it accurately reports that 2017 is on track to being one of the warmest years on record. Reviewers note this wasn’t as unexpected as the article states, but the fact that 2017 global surface temperatures are that high is a clear reminder that global warming has not stopped or slowed down.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: While generally accurate, the article may overstate how unusual 2017 is shaping up to be. It is very unlikely to set a new temperature record in any of the different global surface temperature datasets (NOAA, NASA, Hadley, Berkeley Earth), and is likely to either be the second or third warmest on record. If 2017 temperatures end up comparable to or slightly below 2015, a year where the El Niño contribution was not that large, 2017 temperatures will be quite warm but “extremely remarkable” might be overstating the case a bit. However, even if temperatures end up being below 2015, the year 2017 will likely be a bit warmer than we’d naively expect simply based on the past warming trend: Victor Venema Scientist, University of Bonn, Germany: The large variety of comical claims that scientists are surprised 2017 will be warm is somewhat annoying, (the Earth is warming, every year will normally be among the warmest recorded) but the facts are otherwise right. Richard Betts Professor, Met Office Hadley Centre & University of Exeter: This article is factually correct in terms of the presentation of the data, but the claim that this is “a surprise to climate scientists” is not correct. The article seems to have been written without awareness of some important and relevant climate science. In December 2016, climate scientists at the UK’s Met Office Hadley Centre predicted that 2017 would be “another very warm year for global temperatures” – see MetOffice news release. I’m giving this a rating of 0 (neutral) because although the scientific content of the article is correct, the headline that this is “unexpected” is incorrect. Eric Guilyardi CNRS Research Director, Université Pierre et Marie Curie & Professor, University of Reading: This article rightly explains that El Niño events, which see the tropical Pacific – a quarter of the planet’s surface – warm by a few degrees celsius, boost the global surface temperature by a few tenth of a degree. So having a year without El Niño being 1°C warmer than the pre-industrial period adds to the evidence that the planet is warming at a pace that is not due to natural variability. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Featured Annotations: The statements quoted below are from the article; comments and replies are from the reviewers. “’Extremely remarkable’ 2017 heads toward record for hottest year without an El Niño episode.” Victor Venema Scientist, University of Bonn, Germany: At the moment, it is more likely than not that 2017 will become the second warmest year of the instrumental period. The warmest was 2016 with El Niño. So this claim is correct. “So it’s been a surprise to climate scientists that 2017 has been so remarkably warm — because the last El Niño ended a year ago.” Victor Venema Scientist, University of Bonn, Germany: 2016 would most likely also have been a record warm year without El Niño. Given the long-term warming trend due to global warming, it was to be expected that 2017 would also be warm. Richard Betts Professor, Met Office Hadley Centre & University of Exeter: The claim that this is “a surprise to climate scientists” is not correct. In December 2016, climate scientists at the UK’s Met Office Hadley Centre predicted that 2017 would be “another very warm year for global temperatures”. 2017 was forecast to be among the warmest on record, but not as warm as 2016, so what is happening is actually consistent with the prediction. “that is a sign the underlying global warming trend is stronger than ever.” Victor Venema Scientist, University of Bonn, Germany: The rate of warming has been about the same since 1980. The warming is only exceptionally strong if you were deceived by people claiming that global warming had/has stopped. “The latest NOAA report is “a reminder that climate change has not, despite the insistence of climate contrarians ‘paused’ or even slowed down,” Mann said..” Victor Venema Scientist, University of Bonn, Germany: Right. “2017 is so unexpectedly warm it is freaking out climate scientists” Richard Betts Professor, Met Office Hadley Centre & University of Exeter: 2017 is not “unexpectedly warm” nor is it “freaking out” climate scientists, because they predicted this! Victor Venema Scientist, University of Bonn, Germany: No, we are not freaked out."
https://science.feedback.org/review/scientists-explain-what-new-york-magazine-article-on-the-uninhabitable-earth-gets-wrong-david-wallace-wells/,-0.7,"New York Magazine, by David Wallace-Wells, on 2017-07-09.",,"""The Uninhabitable Earth""",,,,,"New York Magazine published an article by David Wallace-Wells detailing the potential impacts of climate change if no action is taken to reduce greenhouse gas emissions. Much of the article explores “worst case” scenarios of change in the climate system and the resulting impacts on human populations. Scientists reviewed the article to determine whether the descriptions of those scenarios accurately reflect the state of scientific knowledge. The New York Magazine article has triggered a number of responses debating the merits of the decision to focus on worst case scenarios, but our review simply addresses the scientific accuracy of the article. The reviewers found that some statements in this complex article do misrepresent research on the topic, and some others lack the necessary context to be clearly understood by the reader. Many other explanations in the article are correct, but readers are likely left with an overall conclusion that is exaggerated compared to our best scientific understanding.See all the scientists’ annotations in context This is part of a series of reviews of 2017’s most popular climate stories on social media.UPDATE (15 July 2017):New York Magazine has published an annotated version of its article indicating sourcing, which also incorporates several edits based on scientists’ comments.Read more Update (13 July 2017): The analysis has been updated to include several comments received just after the time of publication. The main conclusion of the analysis is unchanged. GUEST COMMENTS: Michael Mann Professor of Meteorology, PennState University: The article paints an overly bleak picture by overstating some of the science. It exaggerates for example, the near-term threat of climate “feedbacks” involving the release of frozen methane (the science on this is much more nuanced and doesn’t support the notion of a game-changing, planet-melting methane bomb. It is unclear that much of this frozen methane can be readily mobilized by projected warming). Also, I was struck by erroneous statements like this one referencing “satellite data showing the globe warming, since 1998, more than twice as fast as scientists had thought.” That’s just not true. The study in question simply showed that one particular satellite temperature dataset that had tended to show *less* warming that the other datasets, has now been brought in line with the other temperature data after some problems with that dataset were dealt with. Ironically, I am a co-author of a recent article in the journal Nature Geoscience (see e.g. this piece), using that very same new, corrected, satellite dataset, that shows that past climate model simulations slightly **over-predicted** the actual warming during the first decade of the 21st century, likely because of a mis-specification of natural factors like solar variations and volcanic eruptions. Once these are accounted for, the models and observations are pretty much in line—the warming of the globe is pretty much progressing AS models predicted… which is bad enough. The evidence that climate change is a serious problem that we must contend with now, is overwhelming on its own. There is no need to overstate the evidence, particularly when it feeds a paralyzing narrative of doom and hopelessness.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Richard Betts Professor, Met Office Hadley Centre & University of Exeter: While it is clear that ongoing warming of the global climate would eventually have very severe consequences, the concept of the Earth becoming uninhabitable within anywhere near the timescales suggested in the article is pure hyperbole. The author has clearly done very extensive research and addresses a number of climate threats that are indeed major issues, but generally the narrative ramps up the threat to go beyond the level that is supported by science. Daniel Swain Climate Scientist, University of California, Los Angeles: This is an unusual piece in that it accurately describes some of the most dire consequences of unabated global warming but focuses almost exclusively on worst case scenarios. In doing so, it provides a compelling narrative of what could happen in the future, but does not accurately characterize the likelihood of particular outcomes relative to what is justifiable based upon existing scientific evidence. Charles Koven Staff Scientist, Lawrence Berkeley National Lab: The article, while it does thoughtfully discuss some serious implications of climate change, also goes beyond the evidence in a number of instances of its exploration of worst-case scenarios. Alexis Berg Research Associate, Harvard University: This article focuses on the high-end scenario for global warming—high emissions and/or high climate sensitivity, high impacts. It selects recent research that highlights these outcomes. I am sympathetic to the author’s efforts to raise awareness about such scenarios, including impacts that are not always well discussed, and agree that we tend to focus too much on median outcomes. Nevertheless, I think the article would have gained from a more explicit acknowledgement that this particular focus is the goal of the article, as well as a from an explicit discussion (even if only qualitative) of the probabilities associated with these scenarios. Absent that, I am afraid the article, as such, feels misleading, or at least confusing for the general public. In addition, the article contains a number of claims that are factually wrong, and a number of claims that are, to my knowledge, not substantiated by research. I was also concerned by the implied claim that this article, being written after interviews with many climate scientists, somehow reflects scientists’ true opinion about global warming. I don’t believe it does. What this article suggest to me is that we, as as community of scientists and science journalists, need to find a better way to more accurately discuss climate change projections and to convey the associated risks to the public. Peter Neff Assistant Research Professor, University of Minnesota: In what seems an ode to new journalism, the author takes significant literary license to leverage information grounded in truth and paint an apocalyptic picture of extreme future scenarios possibly driven by anthropogenic climate change. Ambiguous references to studies, events and examples severely impairs credibility, as does a complete disregard for nuance. Christopher Colose Research Scientist, SciSpace LLC, NASA Goddard Institute for Space Studies: There are many arguments in this article at the interface of climate instability, socio-political disruption, and general global security. They are, however, clumsily wrapped together and doesn’t reflect well the actual risk posed by climate change. A general comment concerning the climate response to future carbon emissions—one of the emergent insights from decades of research is that linearity is too powerful of a tool to be abandoned lightly. In this context, it is better to think of future warming as smoothly monotonic in our total carbon emissions rather than behaving erratically due to significant non-linearities in the system. There is no evidence that a very abrupt methane source(s) will be readily mobilized into the atmosphere. Such scenarios are not supported by process studies, it is not emerging observationally, and is not borne out paleoclimatically (particularly in the mid-Holocene or Eemian interglacial, where high latitude summers were hotter than today). A small trickle of CH4 release is very plausible, but methane becomes converted to CO2 pretty quickly in Earth’s atmosphere, and there’s already some 200 times more CO2 in the air than CH4. These types of carbon cycle feedbacks will likely give the direct anthropogenic carbon input just a small boost in the near future. Similarly, it’s not obvious that there are any significantly missing feedbacks that should radically alter the linear perspective (certainly, any under-representation of surface albedo feedbacks in current models are unlikely to be the difference maker, since the polar regions make up a very small percentage of the globe and the surface contribution to the planetary albedo is somewhat masked by clouds). A Younger Dryas event today would likely be quite disruptive (the global mean temperature changes were quite modest, but the extratropical temperature re-organizations would still be significant); however, the processes leading to an event like this are pretty unique to a glacial climate undergoing melting, and is unlikely to occur in a warming world during our present interglacial. Actual numbers are important here. The global temperature increase could indeed reach 4-5 degrees by 2100, if humans don’t do anything to our emissions, and beyond this patches of uninhabitable areas (for humans) could start to open up in the tropics, due to heat stress limits imposed by the evaporative limits of our body. Indeed, a world 5+ degrees warmer is a big cause for alarm, even if the world takes a linear path to that mark. The world also does not end in 2100, and while it is tempting to think of later dates as “very far off,” it is worth reminding ourselves that we would live on a different planet had people of the Viking era industrialized and emitted carbon uncontrollably. Nonetheless, the near future climatic fate of New York probably looks more like the climate of South Carolina or Georgia than something from a Mad Max movie. This is still an important basis for concern given that the socio-political infrastructure that exists around the world is biased toward the modern climate. Many of the nightmare scenarios in this article, such as no more food, unbreathable air, poisoned oceans, perpetual warfare, etc. are simply ridiculous, although food security is indeed an issue at stake (see David Battisti’s comments). A “business-as-usual” climate in 1-2 centuries still looks markedly different than the current one, but there’s no reason yet to think much of the world will become uninhabitable or look like a science fiction novel. Victor Venema Scientist, University of Bonn, Germany: We are taking the climate system out of known territories. There will be many surprises and they are what worry me the most. Uncertainty is not our friend and that makes it very hard to say which worst case scenarios are unrealistic. The bigger the stakes the smaller the acceptable risks. A risk someone may be willing to take personally will be larger than the risk one takes with a community, a country or civilization. In that respect it is good that the article explores what surprises may be in store and talks about scenarios that are not likely, but a large part of the total risk. However, unfortunately often statements are inaccurate, wrong or are missing important context. These inaccuracies tend to exaggerate the risks of climate change. Charles Koven Staff Scientist, Lawrence Berkeley National Lab: The article, while it does thoughtfully discuss some serious implications of climate change, also goes beyond the evidence in a number of instances of its exploration of worst-case scenarios. Benjamin Horton Professor, Earth Observatory of Singapore: Most statements in the article are based on peer-reviewed literature. Pierre Friedlingstein Professor, University of Exeter: The article is very alarmist, making very strong statements with very little (if any) support. Implying that climate scientists support the article, which I find hard to believe. Such article does not help at all. It’s just too easy to prove it wrong and hence imply that the entire climate change issue is exaggerated. David Archer Professor, University of Chicago: I do not disagree with the tone of the article in the way that most folks here seem to, and I think it does a service to highlight recent results and ideas throughout the scientific community. However there are inaccurate statements, like about satellite warming since 1998, unsupported conclusions or implications (about past mass extinctions, air chemistry, maybe arctic methane). But I feel that the overall thrust of the article is not wrong, wildly misleading, or out of bounds of the discussion we should be having about climate change. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from the article; comments and replies are from the reviewers. 1. The article attempts to describe a worst case scenario for future warming. “The Uninhabitable Earth” Daniel Swain Climate Scientist, University of California, Los Angeles: The title itself is hyperbolic—there’s not really a plausible climate change scenario in which the Earth becomes truly uninhabitable. That’s not to downplay the very real and very large threat to human lives, economies, infrastructure, ecosystems, and species—and the author does a good job cataloging many of these later in the piece. But taken literally, the title implies a future bleaker than is warranted by existing scientific evidence. “Famine, economic collapse, a sun that cooks us: What climate change could wreak — sooner than you think.” David Archer Professor, University of Chicago: This is well-researched and on target. Unfortunately. “Venus, which was once a very Earth-like planet with plenty of life-supporting water before runaway climate change rapidly transformed it into an arid and uninhabitable sphere enveloped in an unbreathable gas” Richard Betts Professor, Met Office Hadley Centre & University of Exeter: There’s been a lot written about this recently, following the BBC’s publicising of Stephen Hawking’s remarks on it. I don’t think it is accurate to say that Venus was “once a very Earth-like planet” and hence imply that the runaway greenhouse effect could happen here. For one thing, Venus is much closer to the sun. A runaway greenhouse effect on Earth is not thought to be a plausible threat. Ted Letcher Research Scientist, Cold Regions Research and Engineering Lab: My expertise is not in exoplanetary climate, but it is not a definitively accepted “fact” that Venus was once habitable. There is still considerable debate regarding the past habitability of Venus (see links below). Therefore, this statement (which appears to imply that Venus’s climate trajectory is foreshadowing for Earth’s) comes off way too strong. Way et al (2016) Was Venus the first habitable world of our solar system?, Geophysical Research Letters Chassefière et al (2012) The evolution of Venus: Present state of knowledge and future exploration, Planetary and Space Science “parts of the Earth will likely become close to uninhabitable” Alexis Berg Research Associate, Harvard University: I am not sure how one defines habitability. Paucity of resources (e.g., water, vegetation) does not necessarily make a region uninhabitable. So I think that strictly speaking, the author is referring here to studies showing that the combination of heat+humidity may exceed a threshold for human survival some part of the year in already-very-hot-an-humid parts of Southwest Asia (around the Gulf of Persia) by the end of the century1. To my knowledge this kind of result hasn’t been shown for other regions, so in that context, the sentence “parts of”, while technically correct, may imply more than has been established. Note, however, that even without exceeding survival limits, humid heat increases would have impacts on outdoor activities2. Pal and Eltahir (2016) Future temperature in southwest Asia projected to exceed a threshold for human adaptability, Nature Climate Change Dunne et al (2013) Reductions in labour capacity from heat stress under climate warming, Nature Climate Change “there are alarming stories every day, like last month’s satellite data showing the globe warming, since 1998, more than twice as fast as scientists had thought” Carl Mears Senior Research Scientist, Remote Sensing Systems (RSS): This sentence is true for RSS data, but it’s somewhat misleading due to lack of context. If you look at the two most recent versions of the RSS data and compute linear trends Jan 1998-Dec 2016, you find that the new version has a trend value for this period of about 2.6 times larger than the previous version. But, it is good to remember that 1998 is a favorite starting point for those that seek to minimize the perceived threat of global warming. This preference is because 1998 is a relative maximum in global temperature (due to a large ENSO event), and thus trends that start in Jan 1998 are smaller than trends that start in other, nearby years. This means that when the change in trends between datasets is reported as a multiplicative effect, the change appears quite large. However, if one calculated the trends for Jan 1999-Dec 2016 instead, the trends increases by a factor of about 1.6, not 2.6, only a 60% increase. Of course this is still a pretty large increase. The sentence also ignores the other sources of lower-tropospheric satellite data. The newer version of the UAH (Version 6.0) data shows less warming than the previous version. Also, the radiosonde datasets show more warming over this period that any of the satellite datasets (except maybe UAH V5.6), and have done so for years. Alexis Berg Research Associate, Harvard University: If anything, satellite measurements of lower atmospheric temperatures (which is what the author is talking about here, not near-surface, 2-meter temperature), show slightly less warming than predicted by models, a discrepancy that is a topic of ongoing research*. Santer et al (2017) Causes of differences in model and satellite tropospheric warming rates, Nature Geoscience Victor Venema Scientist, University of Bonn, Germany: I would like to add that this “twice as fast” is just for a cherry-picked period. That is about as bad as mitigation sceptics claiming that global warming has stopped by cherry picking a specific period. The real message was that satellite upper air warming estimates are unreliable (still are), but seem to confirm what we know from the surface warming. This story was thus not alarming. If anything is was good news, it reduces uncertainties and as this uninhabitable-article already suggests: uncertainty is not our friend. “Or the news from Antarctica this past May, when a crack in an ice shelf grew 11 miles in six days, then kept going; the break now has just three miles to go — by the time you read this, it may already have met the open water, where it will drop into the sea one of the biggest icebergs ever, a process known poetically as ‘calving.’” Peter Neff Assistant Research Professor, University of Minnesota: Although a particularly dramatic and well-observed example of how floating ice shelves calve icebergs into the ocean, there is little evidence that the crack in the Larsen C ice shelf is directly related to climate change. At best this is subject to considerable debate, as it is difficult to directly connect particular atmospheric and oceanic mechanisms to the cracking of this single, albeit large, proto-iceberg. For a very measured treatment of this topic, see the Guardian article by Professor Helen Fricker of Scripps Institute of Oceanography. Having now just calved an iceberg as of July 12, it is good to hear from the most experience experts how concerning this event is. A really great simple summary is provided by David Vaughan, Director of Science for the British Antarctic Survey, who has worked on the Antarctic Peninsula and studied regional ice shelves for decades. “But no matter how well-informed you are, you are surely not alarmed enough” Daniel Swain Climate Scientist, University of California, Los Angeles: It is quantitatively true—and often under-appreciated—that the likelihood of a “worse than expected” climate future is actually higher than a “better than expected” one. That is: the distribution of climate outcomes is not symmetrical, and as others have previously pointed out, “uncertainty is not our friend“. “This article is the result of dozens of interviews and exchanges with climatologists and researchers in related fields” Alexis Berg Research Associate, Harvard University: This sentence implies, somehow, that the scientific content of this article comes from these scientists, or that they agree with it. I don’t believe that this is entirely the case—e.g. see Michael Mann’s comments—and, the author should have mentioned that as a caveat here. “and we will need to have invented technologies to extract, annually, twice as much carbon from the atmosphere as the entire planet’s plants now do” Charles Koven Staff Scientist, Lawrence Berkeley National Lab: Its unclear in this statement, about the relative amount of negative emissions needed versus the amount of carbon extracted by plants, whether the author means the total amount of photosynthesis by plants (which would be a false statement) or the total difference between photosynthesis, respiration, and disturbance (which would be a true statement). Plants photosynthesize about 120 petagrams of carbon per year, whereas the net land sink is more like 2-3 petagrams of carbon per year. It is the latter number that is comparable in magnitude to the negative emissions technologies required. “at least four feet of sea-level rise and possibly ten by the end of the century” Benjamin Horton Professor, Earth Observatory of Singapore: This statement is supported by peer-reviewed literature. 20th and 21st century rates of relative sea-level rise varied from -4 mm/yr to 3 mm/yr, and are dwarfed by potential future rates of 21st century rise, which under high forcing and unfavorable ice sheet dynamics could exceed 2 meters (i.e., a century-average rate of 20 mm/yr) in many locations. “Most people talk as if Miami and Bangladesh still have a chance of surviving; most of the scientists I spoke with assume we’ll lose them within the century, even if we stop burning fossil fuel in the next decade.” Richard Betts Professor, Met Office Hadley Centre & University of Exeter: These places are clearly at high risk of more frequent coastal flooding, but suggesting that we will “lose them within a century” is an exaggeration. Although there are substantial threats of flooding events, much of the country is not actually at risk of permanent indundation this century. Scientists and policymakers in Bangladesh are well aware of the threat of rising sea levels and are actively involved in research and planning on this, and this includes a strong focus on adaptation (as well as on making the case for reducing the threat through mitigation). They point to the example of the Netherlands to show that low-lying countries can adapt and even reclaim land from the sea. Of course this won’t be possible everywhere, especially in wilderness areas such as the Sundarbans which would be impacted by such measures themselves, but talk of the entire country “not surviving” is not a fair reflection of the scientific analysis. 2. Some types of extreme weather conditions, like heatwaves, are expected to increase with future warming. The response of other specific types of weather, such as tornadoes, remains uncertain. “This past winter, a string of days 60 and 70 degrees warmer than normal baked the North Pole” Victor Venema Scientist, University of Bonn, Germany: Regions with open water will stay relatively warm due to the relatively warm water. As soon as ice limits heat flows from the ocean to the atmosphere it can get very cold. Also, in general variability is much stronger in the Arctic—what sounds like a really big warm anomaly to an innocent reader in the USA is thus exceptional, but less so than the numbers suggest. That is context a reader would need to know. Steffensen et al (2008) High-Resolution Greenland Ice Core Data Show Abrupt Climate Change Happens in Few Years, Science “Even if we meet the Paris goals of two degrees warming, cities like Karachi and Kolkata will become close to uninhabitable, annually encountering deadly heat waves like those that crippled them in 2015. At four degrees, the deadly European heat wave of 2003, which killed as many as 2,000 people a day, will be a normal summer. At six[…] summer labor of any kind would become impossible in the lower Mississippi Valley, and everybody in the country east of the Rockies would be under more heat stress than anyone, anywhere, in the world today[…].” Alexis Berg Research Associate, Harvard University: “At two degrees… at four… at six” What is missing here is a discussion of the probabilities of each target, depending on emission scenarios, etc… It’s fine to discuss high-end scenarios, but mentioning probabilities would add context—without deterring from discussing the extreme risks associated, I believe. In general, the language in this paragraph is dire, but, in my opinion, this is an underappreciated consequence of global warming, and the author does well to highlight it. It’s difficult to extrapolate future impacts from one-time events: the 2003 heatwave killed that many people in Europe because it was so far out from the usual distribution, and populations were poorly prepared. In a warmer future, preparedness and reactivity would arguably be improved, so impacts could be reduced. Kristie Ebi Professor, University of Washington: The article highlights worst case projections of the intensity of heatwaves, but not of their frequency. Projections indicate return periods of high-mortality heatwaves will shorten over the century and, in some cases, the length of these high-mortality heatwaves will increase. That does not mean these events will occur every day during a summer. In many regions, this means a high-mortality heatwave could occurcould approachbecoming an annual event instead of rarely. Further, the projections do not take into account that increased heat-related hazardsare only one factor that influences future risks. The other factors are the extent of exposure, the vulnerability of the exposed population, and the capacity of individuals and communities to prepare for and manage heatwaves. There is growing literature that sensitivity to heatwaves has declined over recent decades, presumably because of some degree of acclimatization to ever higher temperatures, increasing access to air conditioning and cooling centers, better understanding and communication of the risks of high ambient temperatures, and changing infrastructure to reduce urban heat islands. Recent projections using different approaches that take these changes into accountshow that taking these factors into account decreases the magnitude of risks. “unprecedented droughts nearly everywhere food is today produced” Richard Betts Professor, Met Office Hadley Centre & University of Exeter: Actually, overall the general projection is for the world to be wetter on average, with increasing drought in some regions but decreases in others, and increased annual rainfall in many places. The projections are extremely uncertain though, so while it is probably possible to cherry-pick model simulations that suggest increased drought in almost any region (and hence argue, probably fairly, that most places do have some increased risk of drought) these would not be expected to happen concurrently everywhere. A scenario with increased drought in one region would generally see a decrease elsewhere. “a constant swarm of out-of-control typhoons and tornadoes and floods and droughts” Alexis Berg Research Associate, Harvard University: Not to nitpick—we don’t really know what a +6 °C world would look like in detail—but the connection between tornadoes and warming is unclear, at least in the observable record. Daniel Swain Climate Scientist, University of California, Los Angeles: While there is still some uncertainty regarding the response of tropical cyclones (i.e. typhoons and hurricanes) to global warming, there is now evidence that frequency in many ocean basins may actually decrease, but maximum intensity will likely increase. There is indeed evidence that the frequency and intensity of floods/droughts is increasing over much of the globe*, and will continue to do so as the climate warms. This is not necessarily true universally–there will still be quite a bit of spatial and temporal diversity in the response of precipitation extremes to global warming, even in a six-degree-warmer world. But in general, it’s true that there will be dramatically more flood and drought events on a global basis with multiple degrees of warming. Diffenbaugh et al (2017) Quantifying the influence of global warming on unprecedented extreme climate events, PNAS “The strongest hurricanes will come more often” Daniel Swain Climate Scientist, University of California, Los Angeles: This is a plausible claim, especially in a “six degree warmer world”. “tornadoes will grow longer and wider” Daniel Swain Climate Scientist, University of California, Los Angeles: I’m not aware of any scientific evidence for this claim. There has been some work investigating global warming and atmospheric environments conducive to severe thunderstorms (and tornadoes), but to my knowledge there are no peer-reviewed studies that investigate changes in either “length” or “width” of tornadoes. In general, the net effect of climate change upon tornado activity/intensity remains uncertain1, with evidence for increasingly favorable atmospheric environments for tornado formation in some regions2. 1- Tippett et al (2016) More tornadoes in the most extreme U.S. tornado outbreaks, Science 2- Diffenbaugh et al (2013) Robust increases in severe thunderstorm environments in response to greenhouse forcing, PNAS “hail rocks will quadruple in size” Daniel Swain Climate Scientist, University of California, Los Angeles: There is indeed evidence that maximum hail size in severe thunderstorms may increase with global warming (even while overall hail frequency may decrease). Brimelow et al (2017) The changing hail threat over North America in response to anthropogenic climate change, Nature Climate Change Diffenbaugh et al (2013) Robust increases in severe thunderstorm environments in response to greenhouse forcing, PNAS 3. Feedbacks like the release of greenhouse gases from warming landscapes can amplify warming trends, but these processes appear overstated in the article. “In other words, we have, trapped in Arctic permafrost, twice as much carbon as is currently wrecking the atmosphere of the planet, all of it scheduled to be released at a date that keeps getting moved up, partially in the form of a gas that multiplies its warming power 86 times over.” Charles Koven Staff Scientist, Lawrence Berkeley National Lab: Most work on studying the dynamics of greenhouse gas balance in degrading permafrost systems, both as based on field measurements and as represented in ecosystem models for making climate feedback projections, seems to point to methane release being a relatively minor pathway for permafrost carbon to be released to the atmosphere, at least for terrestrial permafrost sources (which comprise most of the carbon mentioned here). It is true that terrestrial permafrost systems emit methane, but most of that methane is from recently photosynthesized carbon rather than older permafrost sources, and most of the carbon released from the older permafrost sources is released as either carbon dioxide or dissolved organic carbon rather than methane. So, while uncertainty on this issue remains high, and permafrost thaw is a potentially strong feedback process, this feedback seems likely to be dominated by carbon dioxide rather than methane. A specifically misleading thing about these numbers, which are a metric called “global warming potential”, is that their units are based on the mass of the gas. Since the question here is whether a given atom of carbon will be emitted to the atmosphere contained within either a molecule of carbon dioxide or a molecule of methane, you have to take into account the fact that the molecule of carbon dioxide is much heavier, because of the two oxygen atoms it picks up in the transformation to that gas, versus the four hydrogen atoms it would acquire in becoming methane. What this means in practice is that you have to divide the global warming potential by the ratio of the weight of the molecules, which is 44/16 or 2.75. So strictly speaking, the 34 and 86 ought to read 12 and 31. This is a separate issue from the timescale one that others point out, and which further makes this comparison misleading. David Archer Professor, University of Chicago: It would be wrong to say, as I often read in the popular press, that all or most of the frozen permafrost carbon will come out as methane, or that Arctic methane will have much impact on climate evolution in the near future. But this article doesn’t exactly say that. Carbon released from permafrost that eventually reaches the atmosphere as CO2 could significantly add to the “long tail” climate impacts from CO2. And this is a much more certain outcome than from methane. The factor of 86 however is totally misleading about the impact of methane vs. CO2. This is an instantaneous impact on radiative forcing (a high-end one at that), and doesn’t reflect the longevity of CO2 (long enough to melt ice sheets) vs. methane (which, emitted now, will mostly be CO2 by the time of peak temperature, say, optimistically, 2050). Vasilii Petrenko, Assistant Professor, University of Rochester: This is incorrect. First, to the best of my knowledge, there currently is not a strong consensus about whether thawing permafrost areas would be a net carbon sink or source. If the only process is that the permafrost carbon is respired by microbes and released to the atmosphere, then there is indeed a large carbon source. However, permafrost areas currently are mostly tundra or tundra-boreal forest biomes, which have relatively low biomass carbon stores. With warming, there would be more forest expansion into formerly permafrost areas, which may compensate for the respiration of permafrost carbon. Second, with regard to large-scale methane release from thawing permafrost, currently available science indicates that this is unlikely. First, despite the ongoing Arctic warming, there is no evidence (from precise atmospheric measurements of methane) that Arctic methane emissions are increasing. Second, an ice core study that I led a number of years ago* indicated that “old” carbon sources (carbon sources depleted in the radioactive carbon–14 isotope) did not play a large role in a rapid methane increase that was associated with a period of warming 11,600 years ago. Permafrost carbon is old and relatively low in carbon–14 content. That warming provides a partial analog to what is happening today. While we can’t with 100% certainty rule out the possibility of large methane emissions from thawing permafrost in the future, the scientific data available to date indicate that the probability of such emissions is low. Petrenko et al (2009) 14CH4 Measurements in Greenland Ice: Investigating Last Glacial Termination CH4 Sources, Science Peter Neff Assistant Research Professor, University of Minnesota: The author’s facts about methane are generally accurate, but he amps up concern about catastrophic release of methane from permafrost beyond what evidence supports. Scientists also investigate whether methane frozen at the seafloor of some continental shelves can be catastrophically be released to the atmosphere. However, existing evidence suggests that natural processes prevent catastrophe. Marine methane (gas hydrates) are heavily processed in the water column, and no contribution to the atmosphere has yet been observed. See an excellent review by Carolyn Ruppel of the US Geological Survey and John Kessler of the University of Rochester*, which was also summarized in the popular press. Ruppel and Kessler (2017) The interaction of climate change and methane hydrates, Reviews of Geophysics “The IPCC reports also don’t fully account for the albedo effect (less ice means less reflected and more absorbed sunlight, hence more warming); more cloud cover (which traps heat); or the dieback of forests and other flora (which extract carbon from the atmosphere). Each of these promises to accelerate warming” Charles Koven Staff Scientist, Lawrence Berkeley National Lab: This statement is a mixture of true and false claims. Physical feedbacks like albedo and cloud cover are most definitely included in Earth system models (ESMs) that are used to make future climate projections, so while the phrase “fully account for” isn’t well defined, the statement as written seems incorrect. As of the 5th IPCC report, biogeochemical feedbacks from permafrost were not explicitly taken into account in fully-coupled ESM simulations. However, some simulations to quantify permafrost CO2 and CH4 feedbacks had been done as of that time and reported in the assessment text, and since then these types of studies have been expanded. The central estimate of the additional contribution of warming from these permafrost feedback processes is on the order of about 20 Pg C released per degree celsius global mean temperature change—or in physical terms about 0.1 watts per meter squared per degree Celsius—which is an important contribution to warming but likely less catastrophic than presented here. However, the uncertainty on these projections does remain high and I don’t think we can completely exclude the possibility of more serious permafrost-driven feedbacks yet. Feedbacks arising from forest dieback is something that is included in some but not all ESMs used to make climate projections (i.e., those that have a “dynamic vegetation” component as opposed to a static, prescribed biogeography). Most carbon cycle models used in ESMs for climate assessments have extremely simplified treatment of forest mortality processes but, some do try to resolve this process, so while the uncertainty due to this process is extremely high and poorly captured in current ESM-based projections, it is not correct to say that it is not accounted for at all. Also, the text implies that all feedback processes are positive, destabilizing feedbacks, which isn’t the case. There are also numerous negative, stabilizing feedbacks, that exist in the planet and that are also captured to various degrees in our models of the planet. As with the positive feedbacks, the uncertainty on these is large and most likely it is poorly captured by the current generation of ESMs. Ted Letcher Research Scientist, Cold Regions Research and Engineering Lab: “More cloud cover (which traps heat)” is a gross over-simplification regarding the role of clouds as a tuning knob for Earth’s climate. While it is true that clouds can act as a blanket and trap more heat, they also serve to reflect sunlight (see the prior sentence regarding the albedo effect). Which cloud effect ultimately wins out has to do with the optical thickness of the cloud (how reflective it is) and (as a rough approximation), the cloud height. As a quick rule: Higher clouds will act better as a blanket since they are both colder (and therefore radiate less energy to space) and typically optically thin. Conversely, lower clouds act more as a reflector since they are warmer and optically thick. The IPCC report does generally show a net positive cloud feedback, indicating global cloud feedbacks will lead to additional warming, but cloud feedbacks are extremely complicated and highly uncertain. Alexis Berg Research Associate, Harvard University: I am not sure what the author means here. The climate models whose projections the IPCC reports are based on definitely account for the changes in albedo from reduced sea-ice and snow cover as the world warms (although not necessarily changes in glaciers and ice caps extents—e.g. Greenland—which is maybe what the author means here), as well as the effect of changes in clouds (actually, the largest source of uncertainty in climate models projections); most models also now account for changes in vegetation and include an interactive carbon cycle (for instance, how a reduction in forest diminishes the land carbon sink). 4. Climate change in Earth’s past can be used to understand the workings of the climate system and refine our expectations for the long-term impacts of modern warming. “In fact, all but the one [extinction event] that killed the dinosaurs were caused by climate change produced by greenhouse gas. The most notorious was 252 million years ago; it began when carbon warmed the planet by five degrees, accelerated when that warming triggered the release of methane in the Arctic, and ended with 97 percent of all life on Earth dead.” David Archer Professor, University of Chicago: Other agents of destruction have been invoked for the end Permian extinction, involving toxic fluorine fumes from volcanic emissions or sulfides from the deep sea. Lee Kump Professor, PennState University: Climate change accompanies all of the mass extinctions, although severe warming isn’t necessarily always to blame. For example, the extinction at the end of the Ordovician occurred during a brief, enigmatic glaciation. The “notorious” extinction 242 million years ago, at the end of the Permian, clearly (based on oxygen isotope proxy data) was accompanied by significant global warming likely triggered by the eruption of the “Siberian Traps” volcanoes, with concomitant buildup of carbon dioxide. Whether methane was released remains speculative, although not unlikely. The species extinction percentage in the ocean could have approached 97%, the proportion was likely lower on land. “the geological record shows that temperature can shift as much as ten degrees or more in a single decade” Alexis Berg Research Associate, Harvard University: I am not sure, again, what the author is referring to here. Ice cores have shown that Greenland temperatures can swing by as much as 10 °C during glacial-interglacial transition*, yes, but we are not talking about global mean temperature here, more about swift reorganization of atmospheric circulation in interglacial glacial transitions that leads to strong regional change in the Arctic. I am unaware of studies showing past global-scale warming of 10 °C in a decade. Note, however, that even global warming of a few degrees C in a century or two would be extremely fast, by geological standards. “The last time the planet was even four degrees warmer, Peter Brannen points out in The Ends of the World, his new history of the planet’s major extinction events, the oceans were hundreds of feet higher.” Alexis Berg Research Associate, Harvard University: I don’t know what time period the author is referring to here, but closer to us, during the last interglacial (roughly 120,000 years ago), Earth was ~2 °C warmer than temperatures in the 19th century, and sea levels were about 5-6 meters higher. This suggests that even “good-case, 2 °C” long-term warming in our future could also raise oceans by that much eventually, even if the pace of that rise (and thus the amount of rise by 2100) is uncertain. “Things almost certainly won’t get that hot this century, though models of unabated emissions do bring us that far eventually.” Alexis Berg Research Associate, Harvard University: This brings up an important point: while historically, IPCC-type projections stop in 2100 by convention, warming does not stop then, in particular for very high (perhaps implausibly high) greenhouse gas emission scenarios: warming goes on in the following centuries, up to ten of degrees in the worst case. Source: IPCC Note that the larger the warming, the larger the uncertainties between climate models (the shading). 5. Warming and drought will negatively impact agriculture—varying with the crop and the region. “The end of food” Richard Betts Professor, Met Office Hadley Centre & University of Exeter: This is hyperbole.Yes there are threats to crop production and other aspects of food security, but the scientific analyses do not suggest an actual “end of food”—it is more a case of regional winners and losers. Not all current food-producing regions are projected to lose their productivity. A redistribution of production would still still be a major issue that society will need to deal with, and may well require growing crops in new places, but this is not the same as suggesting that food supplies will completely come to an end. “the basic rule for staple cereal crops grown at optimal temperature is that for every degree of warming, yields decline by 10 percent. Some estimates run as high as 15 or even 17 percent. Which means that if the planet is five degrees warmer at the end of the century, we may have as many as 50 percent more people to feed and 50 percent less grain to give them.” David Battisti Professor of Atmospheric Sciences, University of Washington: These numbers stem from the results of controlled field sites (in, for example, the Philippines, India and Mexico) and refer to the impact of local temperature changes on yield, all else being equal. (Also, note that the major grain producing regions are in the midlatitudes, where the projected temperature increases are substantially greater than the projected global average temperature increase.) The projected changes in precipitation are sufficiently uncertain that it is not possible to quantitatively account for the impact of their changes, although the IPCC 2013 WG1 Report concludes: “In many mid-latitude and subtropical dry regions, mean precipitation will likely decrease, while in many mid-latitude wet regions, mean precipitation will likely increase under the RCP8.5 scenario.” (In IPCC lingo, “likely” is greater than 2/3 chance.) Finally, there is also a fertilization effect associated with increasing CO2, although studies have shown that the deleterious impact of increasing temperature far outweigh the impact of increased CO2. Alexis Berg Research Associate, Harvard University: Well, for one thing, if food supplies decrease by 50%, one could argue that it is unlikely population would increase by 50% in the meantime… More to the point, the back-of-the-envelope calculation from the author, here, implies that all crops are grown at optimal temperature, which they are not. Exact, global impacts of global warming on agriculture are difficult to quantify. One must also account for the effect of increased atmospheric CO2 on plant photosynthesis, as well as precipitation changes, which are uncertain in particular over land in the Tropics. Adaptation and management could also influence changes a lot. Generally, the estimate has been that warming would be neutral for mid-and high latitudes, up to a point, while being detrimental to agriculture in low latitudes. But again, global, quantitative impacts are uncertain, especially for large warming. I haven’t seen studies suggesting a global decrease by 50%. “as the pathbreaking work by Rosamond Naylor and David Battisti has shown, the tropics are already too hot to efficiently grow grain, and those places where grain is produced today are already at optimal growing temperature — which means even a small warming will push them down the slope of declining productivity.” David Battisti Professor of Atmospheric Sciences, University of Washington: This statement is mostly accurate. To be more precise, it would read “Temperature in the tropics is already greater than the optimal temperature for growing the major crops (rice, wheat, maize). Most of the major grain-producing regions of the world are in the midlatitudes (e.g. the US, Europe, Ukraine, China), where today growing season temperatures are nearly optimal. Hence, warming due to increased CO2 will indeed decrease the yield of these crops in these high-producing regions.” “with some of the world’s most arable land turning quickly to desert” Alexis Berg Research Associate, Harvard University: What regions? Is this a statement about the present, or the future? If about the present, I am unaware of major arable land regions currently facing desertification. Current drought trends—whether droughts, on the global scale, are increasing in extent and/or severity—and their future under global warming, is still somewhat uncertain and a topic of ongoing research. “Precipitation is notoriously hard to model, yet predictions for later this century are basically unanimous: unprecedented droughts nearly everywhere food is today produced. By 2080, without dramatic reductions in emissions, southern Europe will be in permanent extreme drought, much worse than the American dust bowl ever was. The same will be true in Iraq and Syria and much of the rest of the Middle East; some of the most densely populated parts of Australia, Africa, and South America; and the breadbasket regions of China.” David Battisti Professor of Atmospheric Sciences, University of Washington: In general, there is large uncertainty in how precipitation will change due to increased greenhouse gases, including the Sahel in Africa, Australia, and many of important grain producing regions of the world (e.g., the US, Ukraine, China). Under high emission scenarios, models consistently project annual averaged drying in a few places by the end of the Century: e.g. southern Europe, northern Africa, and southern Africa. The IPCC 2013 WG1 Report concludes: “In many mid-latitude and subtropical dry regions, mean precipitation will likely decrease, while in many mid-latitude wet regions, mean precipitation will likely increase under the RCP8.5 scenario.” (In IPCC lingo, “likely” is greater than 2/3 chance.) Alexis Berg Research Associate, Harvard University: This is not true for precipitation. See the right panel on the plot below: What the author is probably referring to is drought projections not based on precipitation alone, but rainfall+temperature, as shown for instance by the Palmer Drought Index. However, there is a debate as to how best to interpret such projections in terms, for instance, of impacts on vegetation (and crop yields) or water resources*. So I would argue things are more uncertain than the authors implies here. Milly and Dunne (2016) Potential evapotranspiration and continental drying, Nature Climate Change Daniel Swain Climate Scientist, University of California, Los Angeles: I agree with Alexis Berg’s comment above. Projections regarding widespread occurrence of historically unprecedented drought are in most cases the product of very strong warming that overwhelms any changes (positive or negative) in precipitation in terms of net moisture. Obviously, temperature-driven droughts will still have large and adverse consequences for agriculture in many regions—so the broader point made here regarding large risks to food production is reasonable. “None of these places, which today supply much of the world’s food, will be reliable sources of any.” David Battisti Professor of Atmospheric Sciences, University of Washington: Even with no change in the natural variability in growing season temperature, increasing summer averaged temperature will likely lead to increased volatility in grain production in the midlatitudes because of the nonlinear relationship between temperature and yield. See section 7.4 of the IPCC 2013 WG2 Report for a recent summary. Africa and “Iraq, Syria and much of the Middle East” are not on the list of the world’s major grain producer regions. “In the sugarcane region of El Salvador, as much as one-fifth of the population has chronic kidney disease, including over a quarter of the men, the presumed result of dehydration from working the fields they were able to comfortably harvest as recently as two decades ago.” Victor Venema Scientist, University of Bonn, Germany: If this author already writes “presumed result”, I would love to see a reference to the scientific literature. It would be quite surprising if the 1-1.5 °C warming we have seen up now makes such a differences. Source: Berkeley Earth 6. Air quality can be affected by both emissions of pollutants and by weather patterns that contribute to urban smog, for example. Climate change can also affect disease transmission by altering the conditions required by vectors. “The warmer the planet gets, the more ozone forms, and by mid-century, Americans will likely suffer a 70 percent increase in unhealthy ozone smog, the National Center for Atmospheric Research has projected.” David Archer Professor, University of Chicago: Note that ozone concentrations are also determined by emissions of NOx and hydrocarbons, which can be controlled. “[Carbon dioxide] just crossed 400 parts per million, and high-end estimates extrapolating from current trends suggest it will hit 1,000 ppm by 2100. At that concentration, compared to the air we breathe now, human cognitive ability declines by 21 percent.” Alexis Berg Research Associate, Harvard University: There is, indeed, some research showing impairments in cognitive function test scores in people exposed to CO2 concentrations in the 950-1,000 ppm range, and even significantly worse performance when CO2 gets to 1,500 and 2,500 ppm. But note that concentrations greater than ~1,000 ppm are, already today, often found in poorly ventilated rooms and buildings. At even higher concentrations, documented metabolic and health effects start to appear—in fact, the safe limit for permanent, long-term exposure to higher concentration of CO2 does not appear to be well known. It seems like NASA and the Navy set that limit around 5,000 ppm for their crews in submarines and spacecrafts. Allen et al (2016) Associations of Cognitive Function Scores with Carbon Dioxide, Ventilation, and Volatile Organic Compound Exposures in Office Workers: A Controlled Exposure Study of Green and Conventional Office Environments, Environmental Health Perspectives “That is especially bad because the Amazon alone provides 20 percent of our oxygen.” Alexis Berg Research Associate, Harvard University: This sentence somehow implies that deforesting the Amazon would reduce atmospheric oxygen by 20%. This is not true. To quote Wally Broecker, who is cited later in the article: “Simply put, our atmosphere is endowed with such an enormous reserve of this gas that even if we were to burn all our fossil fuel reserves, all our trees, and all the organic matter stored in soils, we would use up only a few percent of the available O2. No matter how foolishly we treat our environmental heritage, we simply don’t have the capacity to put more than a small dent in our O2 supply. Furthermore, the Earth’s forests do not play a dominant role in maintaining O2 reserves, because they consume just as much of this gas as they produce. In the tropics, ants, termites, bacteria, and fungi eat nearly the entire photosynthetic O2 product. Only a tiny fraction of the organic matter they produce accumulates in swamps and soils or is carried down the rivers for burial on the sea floor.”“The Arctic also stores terrifying bugs from more recent times. In Alaska, already, researchers have discovered remnants of the 1918 flu that infected as many as 500 million and killed as many as 100 million” Kristie Ebi Professor, University of Washington: A series of cholera pandemics and 1918 Spanish influenza were global pandemics causing high mortality long before anthropogenic climate change began influencing the geographic range of climate-sensitive health outcomes. The World HealthOrganization andnational health systems are preparing for changes in the intensity of transmission, geographic range, and seasonality of climate-sensitive infectious diseases. Certainly much more needs to be done, but thearticle implies national andInternational public health organizations and institutions will not take action when diseases emerge or re-emerge. This is not consistent with the responses to Ebola, Zika, and other recent events. ” You don’t worry much about dengue or malaria if you are living in Maine or France. But as the tropics creep northward and mosquitoes migrate with them, you will.” Kristie Ebi Professor, University of Washington: The statement about the malaria incidence of malaria doesn’t mention the significant decline in the number of cases over the past several decades based onconcerted publichealth efforts. Continuing and scaling up those programs would protect future populations from any changes in disease incidence associated with climate change. “As it happens, Zika may also be a good model of the second worrying effect — disease mutation. One reason you hadn’t heard about Zika until recently is that it had been trapped in Uganda; another is that it did not, until recently, appear to cause birth defects.” Kristie Ebi Professor, University of Washington: It would be helpful to know the source of the statements about Zika. Zika was first recognized in Uganda, but has not been trapped there. Zika has been moving around the world for the past few years, presumably associated with trade and travel. With limited surveillance of Zika and with limited numbers of cases, it isn’tpossible to say whether the disease caused birth defects beforethe large outbreak lastyear; research isunderway to determine that. 7. The ocean are affected not just by rising temperatures, but by changes in chemistry caused by higher concentration of carbon dioxide in the atmosphere. “That isn’t all that ocean acidification can do. Carbon absorption can initiate a feedback loop in which underoxygenated waters breed different kinds of microbes that turn the water still more “anoxic,” first in deep ocean “dead zones,” then gradually up toward the surface[…]This process, in which dead zones grow like cancers, choking off marine life and wiping out fisheries, is already quite advanced in parts of the Gulf of Mexico and just off Namibia, where hydrogen sulfide is bubbling out of the sea along a thousand-mile stretch of land known as the ‘Skeleton Coast.’” Lee Kump Professor, PennState University: Ocean acidification per se doesn’t enhance anoxia: anoxia (loss of oxygen) results from warming (warm water holds less dissolved gas like oxygen), which would be the consequence of atmospheric CO2 buildup, as might more sluggish ocean mixing. It also is enhanced by increased nutrient delivery to the ocean from more rain and river flow on land under the warmer climate. More nutrients mean more algae growth in the uppermost ocean, more decaying organic matter below the surface, and thus less oxygen. Low oxygen zones would spread as the ocean became warmer and river flow increased as the event progressed. When oxygen is exhausted, bacteria do “breathe” other oxygen-containing compounds including sulfate and respire hydrogen sulfide. The coast of Namibia does experience these extreme conditions episodically, but such conditions are unlikely to spread globally until centuries to millennia of warming and eutrophication have occurred. Hydrogen sulfide likely contributed to the mass extinction, but the warming itself as well as other volcanic emanations like chlorine, fluorine, and sulfur dioxide were equally if not more important drivers of the extinction. The recovery from the extinction did take millions of years. “they do know that in acid waters, oysters and mussels will struggle to grow their shells, and that when the pH of human blood drops as much as the oceans’ pH has over the past generation, it induces seizures, comas, and sudden death.” David Archer Professor, University of Chicago: Human blood chemistry is regulated in a way the sea water is not, so this statement is only marginally relevant. UPDATE (15 July 2017): Here is the list of statements that have been modified from the original version of the New York Magazine article: – added: “To read an annotated version of this article, complete with interviews with scientists and links to further reading, click here.” – modified: “there are alarming stories every day, like last month’s satellite data showing the globe warming, since 1998, more than twice as fast as scientists had thought.” now reads: “there are alarming stories in the news every day, like those, last month, that seemed to suggest satellite data showed the globe warming since 1998 more than twice as fast as scientists had thought (in fact, the underlying story was considerably less alarming than the headlines).” – modified: “the geological record shows that temperature can shift as much as ten degrees or more in a single decade.” now reads: “the history of the planet shows that temperature can shift as much as five degrees Celsius within thirteen years.” – added:“This article has been updated to provide context for the recent news reports about revisions to a satellite data set, to more accurately reflect the rate of warming during the Paleocene–Eocene Thermal Maximum […]”"
https://science.feedback.org/review/breitbart-article-falsely-claims-measured-global-warming-fabricated-james-delingpole/,-1.8,"Breitbart, by James Delingpole, on 2017-07-09.",,"""‘Nearly All’ Recent Global Warming Is Fabricated, Study Finds""",,,,,"This Breitbart article by James Delingpole claims that the observed warming of Earth’s surface temperatures is largely a fabrication by scientists who have altered the measurements. The source for this claim is a document written by three individuals who have no track record of publishing scientific research on the topic, and have not submitted their work to peer-reviewed scientific journals, but simply uploaded a pdf on a wordpress blog. Scientists who reviewed the article found that its claims are false and misleading. Data are indeed adjusted to accurately account for things like changes in the instruments used to make measurements or the relocation of weather stations. However, the impact of these adjustments on the global temperature record is actually small, and the warming trend of the last century would appear to be larger without the adjustments, in contradiction with the claims in the Breitbart article.See all the scientists’ annotations in contextGUEST COMMENTS: Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: In general, their argument about removing cyclical behavior comes from comparing old 1980s NASA GISTemp records to those of today. What they don’t tell you is that the 1980 record in question (in addition to being graphed on a different baseline than all the other series) only comes from around 500 land stations almost entirely in the Northern Hemisphere and does not include any ocean data at all. There is a well known warm period in the mid-to-high latitude land areas of the Northern Hemisphere in the 1930s and 1940s, but it does not really show up much in the oceans and not at all in the S Hemisphere. As scientists have collected more historical temperature records from around the world in the past 35 years, we have created more complete records that show less warmth in that period simply because they cover more of the planet. See the NASA website for a good discussion of this. Ultimately all of these comparisons to past records are a bit of a distraction. We have all the raw temperature records today, and we can compare them to the adjusted data to see what, exactly, adjustments do to the temperature record. It turns out that adjustments actually result in less warming over the past century, not more. If we scientists were “cooking the books”, then we are doing so in the wrong direction.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Peter Thorne Professor, Maynooth University: Firstly, as far as I can tell the report [the article is based on] is not published in the peer reviewed literature, yet that is the strong implication given. Then the central money figure is grossly misleading. It takes the difference between consecutive versions of the NOAA NCEI product and purports that these differences are the adjustments being applied to the raw data. I think the only phrase one could, with any validity, use here is “not even wrong”. Both the series have been adjusted, and to pretend otherwise is either showing willful ignorance or duplicity. Taking the difference solely shows the change in adjustments applied and not the total adjustments as is being implied. Indeed, the total common adjustments being applied to both versions of the NOAA NCEI product dwarf those being shown. And the biggest adjustment of all—and only one that really matters—is that applied to account for the move from bucket measurements to engine room intakes over the oceans in the (pre-)WW2 period. This adjustment serves to greatly reduce (not increase) the centennial scale surface temperature trend. Source: IPCC AR5 Fig 2.16 (The blue line—”ICOADS”—is the uncorrected data.) Finally, the finding of unequivocal warming does not rest solely upon surface temperature records. Rather it relies upon a broad suite of indicators (see e.g. FAQ2.1 of IPCC AR5) that all point unambiguously to the conclusion that Earth is running a fever. These findings and the recent surge in temperatures are corroborated by a broad range of other non-physical indicators (phenology, etc.) and also by a suite of modern reanalysis products. For so many analyses to be wrong is all but impossible. If the authors are correct they must explain away all these very many corroborating lines of evidence put together by a diverse range of groups using a huge range of measurements and analysis techniques. They can’t, and they won’t, instead preferring to cast doubt on small details, and making misleading assertions, all the while fervently hoping that their audience misses the big picture, to sow doubt and confusion. Jennifer Francis Senior Scientist, Woods Hole Research Center: The authors of this article and of the study it references clearly have a very limited understanding of the painstaking methods used to ensure that surface temperature records are based on correct and unbiased measurements. Temperature databases from major scientific groups world-wide agree with each other, and also with measurements from independent sources, such as satellites. Shaun Lovejoy Professor, McGill University: The article is mostly misleading because it gives evidence (a graph) that does not support the interpretation that is in given in the text. A reader would have to be somewhat knowledgeable about global warming to realize that the interpretation is unjustified. Peter Neff Assistant Research Professor, University of Minnesota: In a cursory attempt at both reporting and climate science, the author glibly highlights a document heavy on accusation and light on reasoned engagement with fact. Implying nefarious motives behind temperature measurement bias correction without providing readers any indication of why this is necessary is misleading and a dereliction of the author’s journalistic responsibility. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from the article; comments and replies are from the reviewers. 1. Adjustments for known issues are necessary in any dataset, but the adjustments made to surface temperature data have not inflated the long-term warming trend. “‘Nearly All’ Recent Global Warming Is Fabricated, Study Finds” Victor Venema Scientist, University of Bonn, Germany: The entire study could not have been more wrong in three clear ways. 1. The adjustments are scientifically important, but rather modest for the global mean temperature. 2. The adjustments make the estimated warming smaller, not larger. Below are, for example, the raw and adjusted warming signals of the NASA GISS dataset. The how and why is discussed in this post. 3. Also without any thermometer it would be clear that the Earth is warming. Just look at sea ice, sea level rise, melting glaciers, later river freezing, earlier ice breakup, earlier spring and animal migration, movement of animals, plants, insects and ecosystems towards to poles and up mountains, etc. “the adjusted data” Peter Neff Assistant Research Professor, University of Minnesota: It is surprising that, despite adjusted data being the crux of the arguments made here and in the study referred to, the author never explains why one may need to adjust measurements made on the ground or by satellites. There has been significant media coverage recently of some of the adjustments relating to temperature measurements made by satellites. Simply from a practical standpoint, it is beneficial to consider what is involved in sustaining the orbit of a satellite. Once put into orbit, a satellite will slowly “decay” away from its intended orbit as it is pulled nearer to Earth by gravity and other effects. Unless it has its own propulsion to correct for this, it will eventually be pulled out of orbit. This decay affects the exact time of day during which the satellite repeats measurements over one location. For example, from 1995 to 2005, the time of day that a NOAA satellite (NOAA-14) passed over the equator changed by more than 6 hours. The temperature in Quito at 12pm local time versus 6pm local time is quite different, so the satellite measurement must be corrected for this and other effects. More details from this excellent article by Zeke Hausfather. “alarmist organizations like NASA, NOAA, and the UK Met Office differs so markedly from the original raw data that it cannot be trusted.” Peter Neff Assistant Research Professor, University of Minnesota: These are some of the most respected, independent and transparent institutions collecting and ensuring free and open access to climate data of the highest quality. If it were not for these agencies, our ability to evaluate global temperature trends at all would be in the stone age. It might be more useful to thank these international agencies for providing data with which the author makes their arguments. Victor Venema Scientist, University of Bonn, Germany: The differences between the raw and the adjusted data are small for the global mean temperature. The warming estimated from adjusted data is smaller than it would have been without taking changes in the way observations were made into account. “This chart gives you a good idea of the direction of the adjustments.” Peter Thorne Professor, Maynooth University: The chart provides solely a view as to the changes in applied adjustments between consecutive versions of one product. It does not reflect the totality of the adjustments being applied. Showing total adjustments would highlight that these deltas were dwarfed by the existing adjustments applied to the 2008 version. Specifically, the very large spurious warming resulting from biases in the raw marine data record over the late 1930s / early 1940s. The net effect of adjustments in all datasets is to reduce the centennial timescale warming in all the surface temperature products. Victor Venema Scientist, University of Bonn, Germany: This chart does not show the adjustments. It shows an unsourced graph with the difference between two datasets. This is also due to increases in the amount of data used and thus also increases in coverage. In as far as the reason are adjustments, a likely reason would be the adjustments of the sea surface temperature that make global warming smaller. Older bucket measurements are cooler than modern buoy measurements because the water cools by evaporation between taking the bucket out of the water and reading the thermometer. In the past these adjustments were thought to be larger than modern estimates. So the “scandal” here would be that scientists were conservative in their early estimate of global warming. “The blue bars show where the raw temperature data has been adjusted downwards to make it cooler; the red bars show where the raw temperature data has been adjusted upwards to make it warmer.” Peter Thorne Professor, Maynooth University: It does no such thing as both the series are adjusted. Hence it is impossible from the graph as constructed to make such an inference. To do so would require taking the adjusted data away from the raw data which is not what is being done here. Jennifer Francis Senior Scientist, Woods Hole Research Center: Adjustments are made for good reasons. One of the most common ones is to account for a station located in a growing city, where the urban heat island effect would add spurious warming. In most cases the adjustments reduce, not increase, the warming in the record. “Note how most of the downward adjustments take place in the early twentieth century and most of the upward take place in the late twentieth century.” Shaun Lovejoy Professor, McGill University: Even if all the adjustments were unjustified (as the Breitbart piece implies), they would only change the magnitude of the overall warming by about 0.1 °C; from about 1 °C to about 0.9 °C. This graph is nearly irrelevant to the question of anthropogenic warming! It could also be mentioned that the 20th Century reanalysis* which uses NO temperature data from any stations found almost an identical warming (to within 0.1 °C) as 5 other series based on station data. The information in the Breitbart graph is irrelevant to the issue of anthropogenic warming; it is at most a footnote. Compo et al (2013) Independent confirmation of global land warming without the use of station temperatures, Geophysical Research Letters Lovejoy (2017) How accurately do we know the temperature of the surface of the earth?, Climate Dynamics “Each dataset pushed down the 1940s warming” Victor Venema Scientist, University of Bonn, Germany: The second world war increased the percentage of American navy vessels, which make engine intake measurements, and decreased the percentage of merchant ships, which make bucket measurements. Source: UK MetOffice Engine intake observations are typically warmer than bucket measurements because the water cools due to evaporation before the thermometer is read. That produces a spurious warm peak in the raw data. “cyclical temperature patterns” Victor Venema Scientist, University of Bonn, Germany: The report wants to see the summer heat waves of the Dust Bowl in America in the 1930s in the global average annual mean temperature. The figurebelow shows the summer temperature difference between the Dust Bowl year 1936 and now. The affected area, which was warmer in 1936 than now (blue), is about 2% of the Earth’s surface. 2. The document the Breitbart article relies on has not been peer-reviewed by scientists who work in this field. “The peer-reviewed study by two scientists and a veteran statistician looked at the global average temperature datasets[…]” Peter Thorne Professor, Maynooth University: As far as I can tell the linked report is not accepted for any journal and thus peer-reviewed is willfully misleading at best. Ted Letcher Research Scientist, Cold Regions Research and Engineering Lab: In addition to not being peer reviewed, the study also doesn’t appear to cite ANY peer-reviewed literature to support its conclusions, nor does the report provide any additional references. Furthermore, the report appears to have a clear dismissive tone towards peer-reviewed research and uses dubious language such as “Climate Alarmist”, further straining the credibility of the report this article is based solely on. Jennifer Francis Senior Scientist, Woods Hole Research Center: If this author knew anything about the process of scientific research and publication, he would realize just how ridiculous this statement is. Note that the study reported in this article has not been published in any reputable peer-reviewed journal, undoubtedly because it would never pass muster. 3.The Breitbart article claims that we cannot say whether the Earth has warmed, but many lines of evidence independent from temperature measurements also confirm the warming trend. “used by climate alarmists to argue that recent years have been “the hottest evah” and that the warming of the last 120 years has been dramatic and unprecedented.” Peter Thorne Professor, Maynooth University: The IPCC AR5 concluded that warming was unequivocal. This finding rested upon a wealth of evidence and not solely upon surface records. However, each decade for the past three decades has been warmer than all preceding decades in the instrumental record by a greater extent than quantified uncertainties. This finding applies using older or newer versions of the datasets. “Nearly all of the warming they are now showing are in the adjustments.” Victor Venema Scientist, University of Bonn, Germany: That amounts to the claim that the Earth is not really warming. Even without looking at any thermometer data, even if we would not have invented the thermometer we would know it is warming: Glaciers are melting, from the tropical Kilimanjaro glaciers, to the ones in the Alps and Greenland. Arctic sea ice is shrinking. The growing season in the mid-latitudes has become weeks longer. Trees bud and blossom earlier. Wine grapes can be harvested earlier. Animals migrate earlier. The habitat of plants, animals and insects is shifting poleward and up the mountains. Lakes and rivers freeze later and break up the ice earlier. The oceans are rising."
https://science.feedback.org/review/earth-is-not-at-risk-of-becoming-a-hothouse-like-venus-as-stephen-hawking-claimed-bbc/,Incorrect,"BBC, Stephen Hawking, 2017-07-02","Trump's action could push the Earth over the brink, to become like Venus, with a temperature of two hundred and fifty degrees, and raining sulphuric acid.",,"Incorrect: It is not possible for Earth’s climate to become as extreme as Venus’ climate in the foreseeable future. And even extreme global warming would not be linked to sulfuric acid precipitation, which occurs on Venus because of volcanic emissions of sulfur gas.","While feedbacks (like the release of greenhouse gas from thawing permafrost) can amplify climate change, the effect has limits. In its current state, Earth is not at risk of “runaway warming” that reaches the extreme temperatures of Venus.","We are close to the tipping point where global warming becomes irreversible. Trump's action could push the Earth over the brink, to become like Venus, with a temperature of two hundred and fifty degrees, and raining sulphuric acid.",,"Andrew Dessler Professor, Texas A&M University: This is definitely hyperbole. What’s correct in it is that Venus has a massive atmospheric greenhouse effect, resulting in a surface temperature of 450 °C or 850 °F (compared to Earth’s of 14 °C or 58 °F). And basic physics tells us that, as we add greenhouse gases, we increase the strength of our own greenhouse effect. That said, we are far, far, far away from either becoming Venus or the amount of warming suggested by Hawking. Best guess warming of the 21st century is a few degrees C. Make no mistake, this could be terrible for humans and ecosystems, but it’s a lot less than suggested above. And while I don’t think the planet is near a “tipping point,” I do think that climate change is already irreversible because of the long lifetime of CO2 in the atmosphere (centuries to millennia) and the large heat capacity of the oceans. It will take 10,000s of years after CO2 emissions cease for the climate to cool back down to pre-industrial levels (unless we geoengineer). That means that the decisions we make on emissions over the next few decades will determine the climate for the next many thousands of years. To me, this is one of the most troubling parts of the climate change problem. Finally, where does “raining sulphuric acid come from”? That makes no sense—why does a warming climate lead to more sulfur in the atmosphere? That seems completely unsupportable. Christopher Colose Research Scientist, SciSpace LLC, NASA Goddard Institute for Space Studies: As brilliant as Stephen Hawking is, fortunately for life on Earth, this comment is not correct. Venus is actually much hotter than 250 degrees (on any conventional temperature scale), but the pathway it took to being a hot, dead world and a completely failed biosphere is virtually impossible to achieve on modern Earth. The key to achieving a runaway greenhouse on Earth is for our planet to absorb more energy from the Sun than it can actually lose to space at longer wavelengths. There are a few limits to the rate at which bodies can lose energy. One simple limit that applies for a bare rock in space is the Stefan-Boltzmann law, which caps the emitted energy at a constant multiplied by the fourth power of the object’s temperature. In this case, the temperature of the rock will simply be whatever is required for it to emit infrared energy as the same rate at which it gets from the Sun. However, another limit arises in a very moist atmosphere due to the infrared absorption features of water. On modern Earth, adding CO2 to the atmosphere means you decrease the emission to space, but the eventual warming of the planet will increase the emission to space. The net result is that the emission to space is essentially unchanged as a consequence of a break-even “tug of war” between CO2 absorption and temperature. In a very hot, steam atmosphere, however, the emission to space could become decoupled from the surface temperature entirely, and the planet would keep getting hotter if it absorbed more energy than it could shed off. Eventually, at the critical point of water (~705 °F) there is no density discontinuity between the liquid and vapor phases, the ocean surface loses its distinct character, and the ocean is the atmosphere. Earth’s fully vaporized oceans would give a surface pressure of about 270 modern atmospheres. Liquid water is not stable at the surface of Venus today, which is over 850 °F. An ancient vaporized ocean on Venus (for which there is some isotopic evidence for) would eventually be lost to space by the breakup of high altitude water by intense wavelengths of sunlight; this sustained water loss does not occur on Earth due to very cold temperatures in the upper troposphere, which keeps most of the vapor near the surface. In fact, the modern state of Venus (a hot planet with about 90 Earth atmospheres of CO2) can be described as a “post-runaway phase” arising because Venus lost nearly all of its water. On Earth, most of the oxidized carbon is in carbonate rocks, which form in the presence of surface liquid water. Indeed, this is the long term sink of carbon in Earth’s atmosphere, and the eventual (hundreds of thousands of years from now) removal mechanism for the excess anthropogenic CO2. However, these carbonates cannot be deposited on Venus. Instead, with no carbon sink,Venus contains a comparable amount of carbon as Earth does, except it is in the atmosphere rather than locked up in carbonate rocks. Luckily, Earth does not absorb enough Sunlight for this runaway scenario to be a credible threat. Adding CO2 to the atmosphere would never bring Earth near the critical point of water or lock Earth into a state where it can’t lose enough energy to cool off. It is theoretically possible, however, to make modern Earth hot enough such that the upper atmosphere becomes quite wet and conducive to substantial water loss to space. Such a large atmospheric warming also elevates the tropopause height well into the modern stratosphere, and large ozone concentrations could not occur in the presence of tropospheric water vapor content, so the UV protective ozone layer would be engulfed. In this scenario, huge amounts of water could still be irreversibly lost to space without a complete vaporization of the ocean. Such a scenario would still be unlikely to occur, however, even if humans burned all of the fossil fuel reserves, and would require many tens of degrees of additional warming. A somewhat more credible concern that could occur at CO2 concentrations of ~2,000 ppm (a few doublings relative to today) is opening up regions of the globe where humans can’t lose body heat efficiently[1]. Hyperthermia would be induced within hours in significant fractions of the planet for global temperature rises of 15-20 °F or so. This is still a bit outside the bounds of what we expect to occur this century. Hawking is correct that unabated fossil fuel emissions will continue to warm the planet. A smooth warming trend is still a major problem for social infrastructure, however, even if there were no major tipping points. While there may be irreversible events in subcomponents of the climate system, such as melting of the Greenland ice sheet, or die-off of the Amazon, there is no magic threshold at which warming goes from benign to irreversibly terrible. Therefore, we should still focus on limiting the magnitude of future warming, despite the fact that Earth will not become Venus. [1] Sherwood and Huber (2010) An adaptability limit to climate change due to heat stress, PNAS Alexis Tantet Postdoctoral researcher, Hamburg University, Meteorologisches Institut: According to the Fifth Assessment Report of the IPCC (Chap. 12)[1], it is likely that global mean temperature will rise by 0.3 to 1.7 degrees C by the end of the 21st century compared to the end of the 20th century for the lowest scenario of greenhouse gas emissions, or 2.6 to 4.8 degrees C for the highest emissions scenario. The magnitude of this increase is largely dependent on our ability to curb greenhouse gases emissions. As one of the major contributors to greenhouse gases emissions, the role of the USA in determining which scenario will be followed cannot be undermined. There is on the other hand low confidence and little consensus on the likelihood that the climate system will face abrupt and irreversible changes over the 21st century[1] and there is absolutely no evidence that the climate of the Earth could become like that of Venus. While present day concentrations of greenhouse gases exceed the range of concentrations recorded in the past 800,000 years, global mean surface temperatures were about 1.9 to 3.6 degrees C higher than for pre-industrial climate during the mid-Pliocene (about three million years ago), and one has to go as far as the Early Eocene (about 50 million years ago) to find temperatures higher by 9 to 14 degrees C (see IPCC Chap. 5). [1] IPCC (2013) Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change Ken Caldeira Senior Scientist, Carnegie Institution for Science: The Earth is not at risk of becoming like Venus. We have done climate model simulations in which all available fossil fuels were burned and the resulting CO2 released into the atmosphere. The planet warmed up about 10 °C in these simulations. This was enough to melt all of the ice sheets and produce 60 meters of sea-level rise, but in no such simulation does the Earth become anything like Venus. Winkelmann et al (2015) Combustion of available fossil fuel resources sufficient to eliminate the Antarctic Ice Sheet, Science"
https://science.feedback.org/review/the-atlantic-accurately-reports-study-economic-impacts-continued-climate-change-us-robinson-meyer/,1.3,"The Atlantic, by Robinson Meyer, on 2017-06-29.",,"""The American South Will Bear the Worst of Climate Change’s Costs""",,,,,"This story in The Atlantic by Robinson Meyer describes a new study on the distribution of economic impacts that result from continued climate change in the United States. The study finds that the impacts would not be uniform throughout the country, but would reduce GDP to a greater degree in southern states, for example, while the northernmost states could experience net economic benefits from warmer temperatures. Scientists who reviewed the article indicate that it accurately summarizes the study, although the topic of climate impacts is broad and complex, and can inevitably benefit from additional context.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field. Kenneth Gillingham Associate Professor, Yale University: The article is well written, engaging, and correctly described the findings of the Science article. It could have been more introspective about what the results of the Science article actually mean. (E.g. do the results still hold if the geographic distribution of population and economic activity changes in response to climate from 2012 levels? Are the differences between the south and north robust to a broader range of uncertainty than the limited uncertainty examined in the Science article?) Frances Moore Assistant Professor, University of California Davis: The article accurately describes the findings of the paper it is discussing, which is an important scientific contribution. It points out the key conclusions and contributions correctly. Gary Yohe Professor of Economics and Environmental Studies, Wesleyan University: The study makes an enormous contribution by updating aggregate economic reaction functions (sectoral and locational) across a large portion of the economy calibrated in currency and percentage changes in income for the end of the century) that will inform integrated assessment modeling efforts and estimates of the social cost of carbon for the United States. Even though it is not completely comprehensive (so the estimates and ranges continue to be lower bounds of actual totals), the estimates are higher than earlier numbers and ranges because the analysis covers more ground very carefully and digs down to county level climate risks. Spatial variability makes the aggregates less subject to the downward push of aggregating over wider areas (i.e., highs and lows do not cancel as much). Estimates of the social cost of carbon for the US should now be higher than before (they have persistently been orders of magnitude smaller than the world before now—a fact that led the EPA and the Supreme Court, to name two interested bodies, to use global estimates for the value of removing carbon emissions by, for example, raising CAFE standards for vehicles). Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time."
https://science.feedback.org/review/new-york-times-story-highlights-the-growing-number-of-extremely-hot-days-in-a-warming-world-brad-plumer-n-popovich/,1,"The New York Times, by Brad Plumer, Nadja Popovich, on 2017-06-22.",,"""95-Degree Days: How Extreme Heat Could Spread Across the World""",,,,,"This article in the New York Times is organized around maps of projected increases in extremely hot weather because of human-caused climate change. Scientists who reviewed the article indicate that climate model projections are accurately represented, and some of the impacts of hot weather (e.g. impacts on health, crop yields) are briefly summarized.See all the scientists’ annotations in contextGUEST COMMENTS: Camilo Mora, Assistant Professor,University of Hawaiʻi at Mānoa: Overall, I think this is a great article and tool. We certainly need to increase people’s understanding of this problem and this certainly helps with that. Kristie Ebi, Professor, University of Washington: The article describes projections of extreme heat days by the end of the century, providing further support for a well-known risk of climate change. The projections are based on exposure-response relationships from a period when there was generally low awareness of the risks of extreme heat. Awareness has been increasing with the frequency and intensity of heatwaves, as has implementation of heatwave early warning systems and other adaptation options, resulting in a decline in heat-related mortality in recent years in many locations. As heatwave-related mortality increases, it is difficult to imagine individuals and governments not taking action to reduce risks. Much better understanding is needed of how to motivate a proactive adaptation. The extent to which air conditioning could be an effective option in low and middle income countries will depend on how development will evolve in these countries, including electrification. The projections confirm the importance of rapid reductions in greenhouse gas emissions to avoid larger risks later in the century.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Andrew King Research fellow, University of Melbourne: The article is accurate and interesting. I think there could be more clarity around the global warming trajectories that are used here, but otherwise the article is very good. Steven Sherwood Professor, University of New South Wales: The study’s claims all appear to be based on sound, peer-reviewed research. The claims are in line with longstanding predictions and are not cherry-picked or unrepresentative, although there are uncertainties as always in any prediction. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-away: The statements quoted below are from the article; comments and replies are from the reviewers. Continued greenhouse gas emissions will cause Earth’s climate to warm, which means (in part) that extremely hot days will occur more frequently. “Global warming under Paris pledges” Andrew King Research fellow, University of Melbourne: There is a risk that some people might confuse the term “Paris pledges” with the 1.5- and 2-degree C targets that came out of the Paris Agreement. “In this scenario, countries would take some measures, but not drastic ones, to curb emissions — roughly the trajectory of the current pledges under the Paris climate agreement.” Andrew King Research fellow, University of Melbourne: The map is based on the medium-emissions trajectory of RCP4.5, which is roughly in line with the combined current pledges from the Paris Agreement. It would be useful if the article noted that this trajectory is not in line with either the 1.5- or 2-degree global warming targets from the Paris Agreement. “That’s likely to rise to a range of 137 to 200 days per year.” Andrew King Research fellow, University of Melbourne: The article doesn’t hide the fact that there is fairly high uncertainty in these projections. This helps the reader understand the confidence in the projected changes."
https://science.feedback.org/review/energy-secretary-rick-perry-incorrectly-claims-co2-not-primary-cause-climate-change/,Incorrect,"CNBC, Rick Perry, 2017-06-19",Most likely the primary control knob [on climate change] is the ocean waters and this environment that we live in.,,"Misleading: While oscillations in the distribution of ocean temperatures are an important source of natural variability, this does not change the total amount of energy in Earth’s climate system. The increase of carbon dioxide and other greenhouse gases is the primary reason for modern global warming.  Lacks specifics: It is unclear what climatic factors are or are not included in the phrase “and this environment that we live in”.",The best scientific understanding of modern climate change is better summarized by the title of a 2010 study published in the journal Science: “Atmospheric CO2: Principal Control Knob Governing Earth’s Temperature”.,"No, most likely the primary control knob [on climate change] is the ocean waters and this environment that we live in.",,"Patrick Brown Assistant Professor, San Jose State University: If we define climate change as the increase in global temperatures that have been observed since the industrial revolution, then Secretary Perry’s statement is false. Human-caused increases in atmospheric CO2 represent the single largest cause of the Earth’s uptake of heat over that time period. The influence of various drivers of climate change on the amount of Earth heat-uptake since 1750. From IPCC (2013)1. It is true that natural changes in ocean circulations, combined with other aspects of “this environment that we live in”, can influence global temperatures from year-to-year and from decade-to-decade. Thus, these natural changes can alternatively mask or exaggerate the long-term warming trend for as long as a few decades2. However, these natural changes tend to “cancel out” in the long-run such that they cannot be responsible for the sustained warming that we have seen since the industrial revolution. 1- IPCC (2013)Summary: for Policymakers. In: Climate Change 2013: The Physical Science Basis 2- Knutson et al (2016) Prospects for a prolonged slowdown in global warming in the early 21st century, Nature Communications Agus Santoso Senior research scientist, University of New South Wales: At first impression, this is actually a not-quite-straight-forward question to answer. It is understandable that someone gives an answer like: “No, most likely the primary control knob is the ocean waters and this environment that we live in.” But such answer is also not correct. Why? First, there should be many knobs in the Earth’s climate system. It is a complex system: its various components (oceans, land, atmosphere, cryosphere) are coupled together and interact with one another. The system constantly fluctuates, and all the knobs are turning. Because it is a coupled system, turning one knob will turn another, etc. This complexity makes it hard for people to comprehend there is one single knob that controls everything. The ocean, and thus the Earth, warms and cools naturally on various time scales, even when CO2 is kept constant. For instance, from time to time more cold deep water is brought up to the surface by the strengthened Trade Winds along the equatorial Pacific. Such condition occurring during a certain year is referred to as the La Niña phenomenon, and in effect the global temperature falls. The reverse is called El Niño. Similar conditions are also seen on inter-decadal time scales—referred to as the Interdecadal Pacific Oscillation. Think of the recent “global warming hiatus” associated with a decadal La Niña-like condition1. So the Pacific Trade Winds can be considered as a knob, right? Imagine if we can control the Trade winds to prevent the Earth from warming or cooling too much. This fact alone makes it hard for certain people to comprehend that there is anything else other than the ocean system that can be considered as a knob. But of course that’s not the only thing. Consider ice cover and the albedo effect, for instance. (E.g. when there’s less sea-ice, more solar radiation is absorbed due to low albedo, warming the Earth—let’s dump more ice on planetary scale so we can reduce global warming?) So how about CO2? Atmospheric CO2 is a potent greenhouse gas and being a greenhouse gas it keeps the planet warm2. Increasing CO2 does warm the planet further, but it’s not as simple as that. We also need to consider its indirect effect: how it changes ocean and atmospheric circulations and sea-ice, glaciers, as changes in all of these then can influence the Earth’s temperature. Further, as circulation changes, weather also changes, so we need to watch out for changes in the pattern and frequency of extreme events. Because we humans as aggregate emit CO2 at a rapid rate, largely due to fossil fuel consumption, CO2 can be considered as a “primary control knob” in the sense that it is the most obvious and available knob for us to turn to influence the climate. Although we cannot directly influence other knobs such as the ocean heat pump mentioned above, we can in effect through the CO2 knob—keep in mind the background noise, i.e., natural variability, still operates. That is not saying that there are no other knobs that we can turn. Land-use is one factor that is also important, as land-use changes can affect climate. Land-use changes also affect atmospheric greenhouse gas concentration (e.g. think of all the smoke coming from burning forests for agriculture). In essence, CO2 is humans’ primary climate control knob. 1- England et al (2014) Recent intensification of wind-driven circulation in the Pacific and the ongoing warming hiatus, Nature Climate Change 2- Lacis et al (2010) Atmospheric CO2: Principal Control Knob Governing Earth’s Temperature, Science Jonathan Gregory Professor, University of Reading and UK Met Office Hadley Centre: If the ocean were the primary control for global mean surface temperature change over decades, we would expect that the ocean below the surface would get cooler while the surface gets warmer, in order to conserve energy. In fact, observations show that the subsurface ocean as well as the Earth’s surface has warmed up over the last few decades. That means the total of the energy stored has been increasing. This extra energy must have come from outside the climate system. Evaluation of the Earth energy budget using observations and models indicates that the increase in stored energy over the last few decades, mostly taken up by the ocean, is about one-third of the extra energy absorbed as a consequence of changes in the composition of the atmosphere due to human activities, predominantly emissions of carbon dioxide. If there were no ocean, the rise in surface temperature would be larger; the effect of the ocean is to mitigate the temperature rise, rather than to cause it. The other roughly two-thirds of the extra absorbed energy has been radiated back to space. Source: IPCC (2013)* IPCC (2013)Chapter 13. In: Climate Change 2013: The Physical Science Basis Shaun Lovejoy Professor, McGill University: [Taken from a review of a similar claim.] Let’s say you are given only three pieces of information: a) The annual average value of the global temperature from 1880 to 1909 b) The atmospheric CO2 concentration for each year c) The effective climate sensitivity With only this, the temperature over the 104 years between 1909 and 2013 could be incredibly well forecast (black line in the figure below), indeed to about an accuracy of ±0.22 °C (purple lines, 90% confidence limits). This tight limit includes the so-called “pause” of the early 2000s. Knowing only the CO2 therefore allows us to predict the temperature more than 100 years into the future. Given that the total change over this time was 1.1 °C, the prediction is correct to within 20%. We know that the CO2 was anthropogenic, therefore its increase was not caused by a change of temperature. We can conclude that CO2 is responsible for much of the change in temperature over the last century. Figure adapted from Lovejoy (2015), Using scaling for macroweather forecasting including the pause, Geophysical Research Letters"
https://science.feedback.org/review/breitbart-misrepresents-research-58-scientific-papers-falsely-claim-disprove-human-caused-global-warming-james-delingpole/,-2,"Breitbart, by James Delingpole, on 2017-06-06.",,"""‘Global Warming’ Is a Myth, Say 58 Scientific Papers in 2017""",,,,,"In an article for Breitbart, author James Delingpole claims to provide 58 scientific papers published in 2017 that show global warming to be “a myth”. This claim is sourced entirely from a list on a blog called “No Tricks Zone”. Delingpole claims “comfort” in “know[ing] that ‘the science’ is on our side”, but he can only do so by fundamentally misrepresenting the scientists’ research. Climate Feedback reached out to authors of the scientific studies in the list of 58 papers that Delingpole claims “corroborate, independently and rigorously” his view that “‘man-made global warming’ just isn’t a thing.” So far, 29 scientists have responded to our request for comment, and all 29 have replied “No” to the question, “Do you agree with the Breitbart article that your study provides evidence against modern climate change caused by human activities?” You can read more about their reactions below.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Peter Neff Assistant Research Professor, University of Minnesota: Despite initially getting the amount of warming the planet has experienced correct, the article goes on to trivialize this global temperature increase and proceeds to provide a 101 course in logical fallacies. This article grossly misinterprets open-access scientific papers by simply looking at graphs and entirely ignoring their meaning as explained by authors in the text. Patrick Brown Assistant Professor, San Jose State University: The article describes a blog post which contains a number of cherry-picked graphs that are irrelevant to the ultimate question of how much humans have contributed to global warming over the past century. It also ascribes conclusions to numerous scientists that the scientists themselves have clearly not made. Dan Jones Physical Oceanographer, British Antarctic Survey: This piece is a logically flawed “straw man argument”. Delingpole claims to have disproven human-driven climate change, but he does not engage with how climate change actually works. Human-driven climate change is primarily about the effects of carbon dioxide on the entire climate system. When more carbon dioxide is added to the atmosphere via fossil fuel burning, more energy ultimately reaches Earth’s surface. This extra energy ends up in the ocean, atmosphere, and cryosphere (i.e., sea ice and land ice). To see the clearest fingerprints of the extra energy added to the climate system from fossil fuel burning, you have to look at the energy content of the entireclimate system over the last several decades (most of the extra energy has gone into the ocean [Levitus et al. 2012]*). Trying to disprove globalwarming in recent decades using regional, seasonal, atmosphere-only temperature trends on centuries-long timescales is very misleading. Levitus et al (2012) World ocean heat content and thermosteric sea level change (0–2000 m), 1955–2010Geophysical Research Letters Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Reviewers’ Comments: The statements quoted below are from the Breitbart article; comments and replies are from the reviewers. “Late 20th century and early 21st century global warming, they show, is neither dramatic, nor unusual, nor scary. Here … are just some of the charts to prove it.” Shaun Lovejoy Professor, McGill University: The four charts presented in the Breitbart article purport to demonstrate that the industrial epoch warming is simply a giant natural fluctuation. But it shows nothing of the sort; it is based on a complete misunderstanding of the space-time variability of the atmosphere. The article commits two common, but fundamental errors that totally invalidate its claims. The firsttwo charts are both of spatially global scale (the northern hemisphere), they illustrate the time scale error. They show northern hemisphere temperatures with millennial scale fluctuations (changes) of the order of 1°C; the so-called “medieval warming event”. Irrespective of whether these reconstructions are accurate (the global—not European—extent of the warming is the question under debate), the change occurred over time scales much longer than the 1°C warming that occurred over the last century. In the pre-industrial period, typical century long, global scale temperature fluctuations were about 0.2°C (i.e. typical century to century changes, see figure below); therefore if the temperature fluctuations followed the usual “bell-curve”, then a 1°C change in a century would have a probability of about one in 3 million of occurring naturally, the giant natural fluctuation hypothesis could easily be rejected. However, it was found that the bell curve under estimates the extreme 3% of the temperature fluctuations: extreme “black swan” events occur much more frequently than expected, yet, even when these rare extremes are taken into account, the probability of a 1°C change in a century is still less than 0.1%, it can easily be rejected1. The other fundamental error is also a scale error, but now in space rather than in time. This error is well exemplified in the fourth graph which shows data indirectly reflecting temperatures in France. Yet France is only about 0.1% of the global surface area, so that large natural fluctuations are common but are not of global significance. A common “skeptic” talking point is the fact that between 1662 and 1762, the temperature in central England increased by nearly 1 °C, i.e., about the same as the global temperature over the last century. Unfortunately for the “skeptics”, central England (greater London) is about 0.01% of the earth’s surface area so that it is not surprising that over the same period, the Northern Hemisphere temperature only increased by 0.2 °C (equal to the typical centennial change!). Finally, the third graph from China combines the two errors: the times scales are way too long and the spatial scales are way too small; it is doubly irrelevant to the question of anthropogenic global warming. Source Lovejoy (2014) 1- Lovejoy (2014) Scaling fluctuation analysis and statistical hypothesis testing of anthropogenic warming. Climate Dynamics“Here’s an unusual one from Guillet et al suggesting that there’s nothing new about wildly early or late grape harvests through the centuries Benjamin Cook Associate Research Scientist, Columbia University: The Guillet et al paper primarily uses wine grapes to look at the impact of the 1257 Samalas eruption (volcanic aerosols cool the climate, delaying grape maturation and harvest). I haven’t read the paper in the detail, but as far as I can tell they do not make any claims about recent warming or harvest trends. Contrary to the claim quoted above, our own work suggest that warming has significantly advanced wine grape harvests over western Europe1. We found, on average, that winegrape harvests have been occurring significantly earlier since 1980 (on average 10 days earlier than the 1600-1900 average). In fact, 2003 was the earliest harvest in the record by about a month. On a broader note, I want to point out that exceptional events in the paleoclimate record do not undermine the case for attributing recent warming to anthropogenic greenhouse gas emissions. We know there have been warm periods in the past, but we have quite a bit of significant independent evidence that recent warming can only be explained by invoking anthropogenic activities. [read the Dr Guillet’s comment below] 1- Cook &Wolkovich (2016) Climate change decouples drought from early wine grape harvests in France. Nature Climate Change “the mild warming of around 0.8 degrees Celsius that the planet has experienced since the middle of the 19th century” Peter Neff Assistant Research Professor, University of Minnesota: This figure [0.8°C] is generally accurate. Global average air temperature has increased by just under 1.0ºC, according to NASA Goddard Institute for Space Studies and confirmed by numerous other organizations: Source: NASA GISS However, it is quite disingenuous to suggest that warming the entire atmosphere by this amount is “mild.” Yes, it is a relatively mild adjustment on your home thermostat, increasing the temperature by less than one degree. For Americans, if your home is heated to 65ºF and you increase the temperature by 1ºF, that is equivalent to about a 0.6ºC increase. Heating the amount of air in your home is quite a different matter than heating the entire atmosphere. Just to start, the atmosphere has an approximate mass of 5 x 10^18 kg—that’s 5 quintillion kg or 11 quintillion pounds. In just over 100 years or so, we’ve increased the global air temperature thermostat by a staggering 0.8ºC—and we’re still emitting the greenhouse gases responsible for the warming. “Several of the papers note that the primary influence on warming appears to be solar activity. Few, if any, entertain the notion that carbon dioxide levels have much to do with it.” Patrick Brown Assistant Professor, San Jose State University: Many of these papers discuss the causes of temperature changes over the past several centuries or millennia. Indeed, solar activity is thought to be one of the primary drivers of the observed temperature variability over this these longer time periods. This is not the case over the past several decades. Over this recent time period we know that the Sun’s intensity has not gotten stronger because we are measuring it with satellites and we know that increasing greenhouse gasses are causing warming. We know that increasing greenhouse gasses are causing warming due to fundamental physical laws—not simply from observing that temperatures and greenhouse gas levels happen to be rising at the same time. “collaborating on studies which all corroborate, independently and rigorously, the increasingly respectable view that ‘man-made global warming’ just isn’t a thing.” Patrick Brown Assistant Professor, San Jose State University: These studies do not make this claim. Most of them are about regional (not global) temperature variations of the distant past. They generally make no claims regarding the causes of global warming over the most recent several decades nor do they make any claims about the amount of warming expected as we continue to increase greenhouse gas concentrations. Peter Neff Assistant Research Professor, University of Minnesota: This false statement is based on a list of figures taken completely out of context. For instance, No Tricks Zone [the blog Breitbart is using as a source] takes a figure from Markle et al., (2017)1 and assumes the x-axis refers to years before present. With this incorrect interpretation, it seems as though ocean temperature anomalies are very low at year 0. However, these plots show the result of simulations of idealized Dansgaard-Oeschger or Antarctic Isotope Maximum events in a general circulation model. Year 0 is simply the beginning of the simulated event and is not displaying actual modern sea surface temperature data (i.e. year 0 is not today, 0 years before present). Not only is this a red herring, it is a completely misinterpreted red herring. They also repeat the favorite Antarctic cooling cherry, taking (and altering) a figure from Mayewski et al., (2017)2 which shows Antarctic-wide climate reanalysis temperature data. As a continent (larger than the US lower-48), Antarctica is not warming. This is because much of high, dry East Antarctica is not warming. However, important areas of Antarctica, including West Antarctica which likely would show about a 0.2ºC per decade warming trend over the reanalysis period (from 1979 to present, since satellites have given good data coverage). Climate is incredibly variable around Antarctica, and also through time (large interannual variability). This is well studied, but if you only look at one graph rather than reading the research papers you will not be aware of this. See: Nicolas andBromwich (2014)New Reconstruction of Antarctic Near-Surface Temperatures: Multidecadal Trends and Reliability of Global Reanalyses. Journal of Climate Bromwich et al (2012)Central West Antarctica among the most rapidly warming regions on Earth.Nature Geoscience 1-Markle et al., (2017) Global atmospheric teleconnections during Dansgaard–Oeschger events. NatureGeoscience 2-Mayewski et al., (2017)Ice core and climate reanalysis analogs to predict Antarctic and Southern Hemisphere climate changes.Quaternary Science Reviews Response From The Authors Of The “58 Studies” Tyler Jones, Research Associate, University of Colorado The West Antarctica temperature plot that was pulled from my 2017 paper is very low resolution, and does not resolve the most recent few 100 yrs. We know from other studies that West Antarctica is currently warming faster than almost any other place on Earth. Furthermore, my paper has nothing to do with global warming or human activities. In fact, I only focus on time periods well before the Industrial Revolution. It is clear that global warming is caused predominantly by human activity. Belinda Dechnik, The University of Sydney My data does discuss sea surface temperaturein the Great Barrier Reef being slightly warmer than present during the mid-Holocene in response to natural climate variability. However, I in no way deny that the current climate is warming, and that anthropogenic effects are proving very detrimental, particularly to reef systems. This article has misunderstood my findings and in no way supports my view on climate change. I am very disturbed indeed that these people have used my article in such a way to try and discredit the serious effects of man-made climate change. Nathan Steiger, Postdoctoral Fellow, Columbia University The blog post maliciously tampered with figures from my paper, removing lines from the figures. My paper is just not relevant to the arguments about global warming. R. Scott Anderson, Professor, Northern Arizona University Although the curve shown in the Breitbart article supports our research, the specific curve cited is not our work, but comes instead from nearby tree-ring research done by Greg Wiles and his co-workers (2014). This is clearly stated in the figure caption in our article, which could have been seen if the article had been actually read. My conclusion from this is that Breitbart was not careful in its compilation, and for me this calls into question their methods for collecting data on other articles. Our conclusions are much more complex, and suggest that post-Little Ice Age warming has occurred, and has affected forests at higher elevations to a greater extent than at lower elevations. Yair Rosenthal, Professor, Rutgers University The data were taken out of context. In fact a previous article (Rosenthal et al., 20013) made the argument that the current warming, as measured by the increase in Ocean Heat Content (OHC), is a reversal of the long-term cooling trend in the preceding centuries and the rate of heat gain is substantially higher than recorded in the past. If anything, these data support global warming as manifested by the recent increase in OHC. Normunds Stivrins, Associate Professor, University of Helsinki Our article (Stivrins et al., 2017, The Holocene) focuses on other subjects than human-induced impacts (climate change). It’s sad that the blogger did not understand what this study is about, but rather took a sentence without context. Our point was that geological aspects can protect glacial ice in the ground but it starts to melt when air temperature increases—in this case when temperature started to increase above today’s temperatures. Note that this is a specific case study where exceptional environmental conditions prevail 8,400-7,400 years ago in western Latvia. Bradley Markle, PhD Candidate, University of Washington My study, and almost all I saw mentioned in the blog post, are studies of climate change in the past. My study investigates connections between different parts of the climate system during climate events that happened over 10,000 years ago. Studying climate change in the past can give context to recent climate changes. However, my study in no way investigates or tries to attribute the causes of recent climate change. It does not deal with human influences on climate. I do not argue that “global warming… is a fake artefact [sic]”. The overwhelming scientific evidence is that the climate is currently changing and that human influences, primarily releasing CO2 into the atmosphere, have a significant impact. Though, again, this is not at all addressed in my study, nor any of the ones quoted that I recognized (though I did not read them all). The blog post and Breitbart article are both misleading and inaccurate, on several levels. Ernesto Tejedor Vargas, University of Zaragoza The article Tejedor et al., 2017 is not a climate-change-denying paper. It is a paleoclimate paper showing, first, a new maximum temperature reconstruction for the last 400 years (including the current warming) and second, a new standardization method in dendrochronology to remove the non-climatic trend. The image in the post does not by any means reflect the message of the paper. That figure is the raw temperature of the CRU dataset in the region, i.e., [I would like the author of the No Tricks Zone post to] remove my name from the blog since it is not reflecting our research conclusion. David Reynolds, Postdoctoral Research Associate, Cardiff University (and co-authors) The article uses Figure 11 from Reynolds et al., 2017 without displaying the figure caption. The caption for this figure clearly states that the data shown have been detrended using a simple linear function in order to highlight the high-frequency (sub-centennial) mean annual sea surface temperature (SST) anomalies. This means we have statistically removed the long-term trend, i.e., the 20th century warming signal. The long-term trend was removed from the observational SST data as the particular proxy data being used for comparison, the marine bivalve growth increment width (GIW), does not record the low frequency change, such as the long-term warming trend. The reason the GIW chronology doesn’t record the long-term trend is because there are changes in the growth rates of the bivalves as they age (older=slower=thinner GIW). The standard procedure (e.g. Butler et al., 2009) for taking these so-called “ontogenetic effects” into account removes the ability of the GIW proxy to record long-term trends while retaining the signal of high-frequency variability. Looking at the non-detrended observational SST data (Fig 1) clearly shows there is a long-term warming trend over the 20th century in northeast Atlantic sea surface temperatures. Fig 1 — The black line shows mean annual sea surface temperatures over the North East Atlantic (50-60oN by 10-0oW). The dashed black line shows the linear trend over the 20th century. The data shown here are the raw data that were then linear detrended for use in Reynolds et al., 2017 Fig 11. Butler et al., (2009) Marine climate in the Irish Sea: analysis of a 489-year marine master chronology derived from growth increments in the shell of the clam Arctica islandica. Quaternary Science Reviews Ulrich Kotthoff, Scientist, University of Hamburg Our project covers the past ~8,000 years. The pollen-based climate reconstructions shown in our article include only two samples that cover the past 200 years. The temporal resolution of our study is thus not suited to reveal human influence on climate since the industrial revolution. Ironically, it might even be that the upper pollen samples are biased by human activity, meaning that human influence on vegetation in our research region (Southern Baltic region) might have hampered the reconstructions, e.g. by deforestation. Last not least, our data shows as well that winter temperatures did strongly increase over the past 4,000 years. One of our proxies indicates a strong temperature increase in the marine realm for the youngest sample. Interestingly, these data are not shown in the Breitbart article. Why? Our discussion of the validity of the different reconstruction methods and our interpretation of the climate signals is not taken into account at all. Matthias Thienemann, PhD Candidate, University of Cologne I do not agree with the Breitbart article that my study provides evidence against modern climate change caused by human activities. My paper deals with climate and environmental change on a larger timescale and does not allow any conclusions about current global warming. Aurel Persoiu, Emil Racovita Institute of Speleology We do not provide evidence against modern climate change caused by human activities because our record stops at AD 1860±20. Ice younger than this age has melted in the past decades: “Historical observations have shown that between AD 1863 and 1982, enhanced melting and related changes in the geometry of the ice block led to the loss of ~100 cm of ice. Based on annual ice accumulation rates derived independently of the current one (between 0.9 and 1.6 cm/year, with a mean value of ~1.3 cm/yr), we estimated an age of AD 1860 ± 20 (similar to 90 cal BP) for the top of the ice core.” The chart featured in the quoted blog article is showing the North Atlantic subtropical sea surface February temperature reconstruction of deMonecal et al (Science, 2000), not our reconstruction. We have used the deMonecal et al data in our figure 3 (panel d) and our reconstruction is in the same figure, panels c (temperature) and g (moisture source). The error in the blog article is clearly visible in the figure, where the label on the left axis reads “Atlantic winter SST”, whereas the figure itself is labeled “East central Europe”. Incidentally, the deMonecal et al data stops at 88 cal BP (similar to AD 1862). Henning Åkesson, Research Fellow, University of Bergen The Breitbart article uses a classic and flawed argument with respect to my paper, namely that “since it was warmer before (cherry-picking Norway in the mid-Holocene, around 6000 years ago), the warming we’re seeing now must be a natural phenomenon”. To infer that humans can’t be behind recent climate warming because climate changed before humans is flawed reasoning. My paper does not concern the causes of climate change, nor does the particular statement referred to in my paper (which is actually itself referring to previously published studies) provide evidence against modern climate caused by human activities. Climate in the mid-Holocene was warming due to a different configuration of Earth’s orbit relative to the sun, while warming of the last decades has been shown by overwhelming evidence (>95 % confidence in latest IPCC report) to be caused by human activities. Fatima Abrantes, Portuguese Institute for Sea and Atmosphere As anyone well informed certainly knows, an average climate warming does not at all mean that every region in the world will warm at the same rate. In fact the impact of such warmth on the atmosphere and in the surface ocean waters causes changes in the atmospheric and oceanic circulation which will have different impacts on different regions. The article on Breibart.com is so bad that the author did not even realize that the figure extracted from my paper is not my new data record but the record of the northern Spain atmospheric temperature anomaly, produced by Martín-Chivelet et al., (2011) that I have used for comparison. Indeed, my paper proves that while in the NW Iberian margin Sea Surface Temperatures (SST) during the 20th century were similar to the Medieval Warm Period ones, in the Algarve region SST shows a general increase of about 2 ºC in the last 50 years. Such results agree with both the global and regional projections that indicate this region of Europe with highest potential vulnerability in regard to current global warming (Climate, 2011). Martín-Chivelet, et al (2011)Land surface temperature changes in Northern Iberia since 4000 yr BP, based on δ13C of speleothems, Global and Planetary Change Branwen Williams, Assistant Professor, Claremont McKenna College, Pitzer College, Scripps College The seawater temperature data clearly show an increase of ~0.8C since 1860. While there are fluctuations in temperature of similar scale preceding that, the drivers of these fluctuations differ. Feng Sheng Hu, Professor, University of Illinois The graph they claimed was evidence from my article in fact was NOT even a result of [ours]. It’s a graph in an article we cited. Rob Wilson, University of St. Andrews Many of the papers are local/regional studies and will not be representative of large scale trends. One also needs to fully understand the uncertainties of these records. The latest attempts of tree-ring based northern hemisphere reconstructions clearly show a warming signal in the recent period. The constituent records may have more local complexity, but this gets averaged out/minimised when combined for large scale analyses*. A good example of what I mean at the local scale is the mention of the Rydval 2017 Scottish work. Rydval was my PhD student. The warming of Scottish summer temperatures are significant within the context of the post 1550 period. Our paper clearly states that there is great uncertainty due to less trees before this. This article does not take into account local scale variability and large scale forcing, the signal of which we see when multiple local scale records are averaged together. Stoffel et al (2015)Estimates of volcanic-induced cooling in the Northern Hemisphere over the past 1,500 yearsNature Geoscience Wilson et al (2016)Last millennium northern hemisphere summer temperatures from tree rings: Part I: The long term contextQuaternary Science Reviews Anchukaitis et al (2017)Last millennium Northern Hemisphere summer temperatures from tree rings: Part II, spatially resolved reconstructionsQuaternary Science Reviews Sébastien Guillet, University of Geneva First of all, it is important to state that the Guillet et al. paper, published in 2017 in Nature Geoscience, never claimed nor concluded that human-induced global warming was a “myth”. The paper merely aimed at reassessing the climatic impacts of the 1257 Samalas eruption on Northern Hemisphere climate using historical archives and tree-ring records. In other words, this study was not designed to answer the question of whether or not the recent warming is historically unprecedented. Let us now have a closer look at the grape harvest date (GHD) plot shown in the Breitbart article written by James Delingpole. The plot is composed of 3 GHD series. The Ile-de-France (IDF) series (purple) spans the period 1478-1977 (with several gaps due to missing observations). The IDF record was published originally by Daux et al. (2012) and Guillet et al. (2017) added a GHD for the year 1258. No GHDs are currently available for the period 1977-2017 and for the Medieval Climate Anomaly (MCA) (ca. 850-1300). Therefore the incompleteness of the IDF record is certainly not suitable for any whatsoever conclusion on whether the past few decades were unusual with respect to other periods such as the MCA. Similar statements can be made for the Alsace (orange) and Burgundy (green) records which cover the period 1700-2005 and 1354-2006 (with several missing values) respectively. We want to stress once again that GHD records shown in Guillet et al. (2017) were solely used to demonstrate that very late harvests occurred in 1258, probably as a result of the climatic anomalies (cold conditions) induced by the 1257 Samalas eruption. GHD records are now recognized as an important regional proxy for spring-summer temperature (Chuine et al., 2004; Meier et Pfister, 2007; Maurer et al., 2009; Garnier et al., 2011). Yet, as with any other proxy, the use of this archive for climate reconstructions comes with limitations and uncertainties. Several researchers have indeed shown that spring-summer temperatures are not the only factor influencing and/or determining grape harvest (Guerreau 1995, Rutishauser et al., 2007, García de Cortázar-Atauri et al., 2010). Changes in agricultural practices, the use of different grape varieties in the same region over time, as well as the political background (e.g. military conflicts, see Garnier et al., 2011) can influence harvest dates and bias the climate signal and therefore the climatic trends contained within the GHD series (García de Cortázar-Atauri et al., 2010). In summary, and given the limitations listed above, extreme caution must be taken before using the French GHD records to claim that global warming is a “massive lie”. We feel that additional studies addressing the limitations of this proxy and filling the numerous gaps existing in the available French GHD series must be carried out before drawing any definitive conclusion. References: Chuineet al (2004), Historical phenology: Grape ripening as a past climate indicator, Nature. Daux et al(2012), An open-access database of grape harvest dates for climate research: data description and quality assessment, Clim. Past. Garcia de Cortazar-Atauri et al (2010), Climate reconstructions from grape harvest dates: Methodology and uncertainties, The Holocene. Garnieret al (2011), Grapevine harvest dates in Besançon (France) between 1525 and 1847: Social outcomes or climatic evidence?, Clim. Change. Guerreau (1995), Climat et vendanges (XIVe-XIXe siècles) : révisions et compléments, Hist. Mes. Guillet et al(2017), Climate response to the Samalas volcanic eruption in 1257 revealed by proxy records, Nat. Geosci. Maurer et al(2009), BACCHUS temperature reconstruction for the period 16th to 18th centuries from Viennese and Klosterneuburg grape harvest dates, J. Geophys. Res. Meieret al (2007), Grape harvest dates as a proxy for Swiss April to August temperature reconstructions back to AD 1480, Geophys. Res. Lett. Rutishauser et al(2007), A phenology-based reconstruction of interannual changes in past spring seasons, J. Geophys. Res. BiogeosciencesJulie Richey and Jennifer Flannery, United States Geological Survey The Breitbart article, and the source it draws from, do not accurately reflect the subject matter or conclusions of our peer-reviewed, published research. Our paper, “Multi-species coral Sr/Ca-based sea-surface temperature reconstruction using Orbicella faveolata and Siderastrea siderea from the Florida Straits,” does not address global warming or its causes directly, and therefore does not, as the Breitbart article claims, “argue that the alarmist version of global warming — aka Catastrophic Anthropogenic Global Warming (CAGW) — is a fake artifact.” Our paper presents a 280-year sea surface temperature record based on the ratio of strontium to calcium in corals we sampled in the Dry Tortugas National Park. It shows that sea surface temperatures measured over many decades in the Florida Straits are variable, and that variation has been dominated for nearly the past three centuries by a natural oscillation called the Atlantic Multidecadal Oscillation. We do observe a 0.8 ºC warming trend in our record from 1970-2010 (section 3.3, page 105 of Flannery et al., 2017). Neither of these findings refutes the role of anthropogenic activity in global climate change. Anthropogenic climate change is characterized by variable climate responses across the globe. No climate record taken at a single point in space is representative of the global climate. Barbara Stenni, Associate Professor, Ca’ Foscari University of Venice Our work agrees perfectly with the results from climate models, which show that Antarctic warming should be significantly delayed relative to the rest of the planet. Furthermore, our work confirms previous work demonstrating that West Antarctica and the Antarctic Peninsula are among the fastest-warming regions on the planet. Andrea D. Tegzes and Eystein Jansen, University of Bergen Firstly, about the graphs: This is the work of Thornalley and co-authors from 2009. The datasets are based on samples from a site just south of Iceland in the northern North Atlantic (denoted by RAPiD-12-1K in Fig. 1), and not on samples from the eastern Norwegian Sea. The two graphs show reconstructed late-spring/early-summer near-surface (0-50m water depth) and sub-thermocline (approx. 100-200m water depth) ocean temperatures at this specific site. Upper-ocean temperatures at this location are particularly sensitive to changes in ocean-circulation patterns, primarily to the northeast extent of the Subpolar Gyre (SPG), and hence the degree of mixing between colder subpolar waters and warmer Atlantic waters (North Atlantic Current, NAC) (Fig. 1). The impact of ocean circulation is more pronounced at sub-thermocline depths. Near the surface, these changes are masked in part by seasonal warming. Figure 1 — The impact of changes in ocean-circulation patterns on upper-ocean temperatures south of Iceland and along the mid-Norwegian Margin. Ocean currents are marked by white arrows. Cold and warm water masses are indicated by blue and red-orange shading, respectively. Thornalley et al. (2009) used samples from the South Iceland Rise (site marked by RAPiD-12-1K), while Tegzes et al. (2017) used samples from the mid-Norwegian Margin (site marked by HA). Secondly, about the quote in the blog post (“Our sortable-silt time series show prominent multi-decadal to multi-centennial variability, but no clear long-term trend over the past 4200 years.”): Tegzes et al. (2017) investigated northward oceanic heat transport along the mid-Norwegian Margin, which is determined both by the temperature and volume of water advected northwards in the Norwegian Atlantic Slope Current (NwASC). We cannot directly reconstruct volume transport. However, by analyzing the coarseness of current-sorted deposits, we can make inferences about past variations in current speed. The sortable-silt time series, mentioned in the quote, are our current-strength proxy records from the mid-Norwegian Margin (site denoted by HA in Fig. 1). When we compared these time series with upper-ocean temperature proxy records from the same location (Andersson et al., 2003; Risebrobakken et al., 2011; Risebrobakken et al., 2003), we found either no correlation or, a seemingly counterintuitive, inverse relationship between the strength of the NwASC and the temperatures of the upper ocean at the mid-Norwegian Margin. Therefore, we concluded that, when investigating past climate, we cannot make inferences about the impact of the NwASC on regional climate solely based on its past strength. We also need independent information about the temperatures of the waters that it transported northwards from the northern North Atlantic. The authors of both papers, Thornalley et al. (2009) and Tegzes et al. (2017), aimed to broaden our understanding of ocean circulation. The coring locations (sites marked by RAPiD-12-1K and HA in Fig. 1) were chosen with that in mind. Reconstructed and measured ocean temperatures at these locations may have a large advective component, and hence should never be used to assess global warming without careful prior analysis. In addition, the sediments south of Iceland did not record the last few decades, and thus cannot be used in any argument about the modern situation. These local or regional patterns do not reflect global or hemispheric temperatures as inferred by the Breitbart article. References: Andersson et al. (2003) Late Holocene surface ocean conditions of the Norwegian Sea (Vøring Plateau). Paleoceanography. Risebrobakken et al. (2011) Early Holocene temperature variability in the Nordic Seas: The role of oceanic heat advection versus changes in orbital forcing. Paleoceanography. Risebrobakken et al. (2003) A high-resolution study of Holocene paleoclimatic and paleoceanographic changes in the Nordic Seas. Paleoceanography. Tegzes et al. (2017) Northward oceanic heat transport in the main branch of the Norwegian Atlantic Current over the late Holocene. The Holocene. Thornalley, Elderfield and McCave (2009) Holocene oscillations in temperature and salinity of the surface subpolar North Atlantic. Nature. Wenfeng Deng, Associate Research Fellow,Guangzhou Institute of Geochemistry Our results indicate that the Current Warm Period (AD 1850-present) is similar to or even warmer than the Medieval Climate Anomaly (AD 900-1300) over the western Pacific. Therefore, the Breitbart article misunderstood and overinterpreted our results and conclusions. Tomi Luoto, Adjunct Professor,University of Jyväskylä Our graph presents the relationship between temperature and precipitation (not a temperature record) and cannot be used to interpret anthropogenic climate change directly. Florin Pendea, Associate Professor,Lakehead University Orillia The claim that our paper Pendea et al. (2017) published in the Quaternary Science Reviews brings support to the notion that anthropogenic global warming doesn’t exist is completely false. The story circulated by Breitbart news represents a gross misunderstanding of the data presented in our paper. The data we present constitutes a record of millennial-scale environmental change in the North Pacific that has no relevance to the discussion around the global warming trend observed during the last 150 years in a vast number of environmental archives around the world. Guocheng Dong,State Key Laboratory of Loess and Quaternary Geology, Chinese Academy of Sciences Our paper published in The Holocene has not shown anything about human-caused global warming. I believe that misunderstanding may have occurred. Miloš Rydval, University of St. Andrews In the Rydval et al 2017 article, we clearly and repeatedlyemphasizethat there is a considerable amount of uncertainty associated with our temperature reconstruction and this generally increases further back in time and is related to, among others, data availability. This point is discussed in considerable detail in the paper and is a matter that was entirely ignored by the source cited in the Breitbart article. Thus, the cited statement: “[the reconstruction] suggests that the recent summer-time warming in Scotland is likely not unique when compared to multi-decadal warm periods observed in the 1300s, 1500s, and 1730s …” was taken out of context and misrepresented. The cited source conveniently omitted the second part of the sentence which highlights uncertainty in the earlier parts of the reconstruction and includes a cautionary statement about the interpretation of those periods. Also, it should be noted that ourstudy provides information about conditions in and around Scotland, and is therefore not a representation of the average global trends of temperature change over time, but instead representslocalscale variability. Importantly, there is nothing in our paper that in any way contradicts recent anthropogenic climate change and its causes."
https://science.feedback.org/review/breitbart-falsely-claims-58-studies-refute-human-caused-global-warming/,Inaccurate,"Breitbart, James Delingpole, 2017-06-06",'Global warming' is a myth — so say 80 graphs from 58 peer-reviewed scientific papers published in 2017.,,"Misrepresents source: Every study author who responded explained that their work did not support the assertion that ""global warming' is a myth"". Read more in a full evaluation of this article...","These studies of past climate do not challenge the well-researched fact that human activities are responsible for climate change, as many of the scientists behind the studies have confirmed.",'Global warming' is a myth — so say 80 graphs from 58 peer-reviewed scientific papers published in 2017.,,"Patrick Brown Assistant Professor, San Jose State University: These studies do not make this claim. Most of them are about regional (not global) temperature variations of the distant past. They generally make no claims regarding the causes of global warming over the most recent several decades nor do they make any claims about the amount of warming expected as we continue to increase greenhouse gas concentrations. Peter Neff Assistant Research Professor, University of Minnesota: This false statement is based on a list of figures taken completely out of context. For instance, No Tricks Zone [the blog Breitbart is using as a source] takes a figure from Markle et al., (2017)1 and assumes the x-axis refers to years before present. With this incorrect interpretation, it seems as though ocean temperature anomalies are very low at year 0. However, these plots show the result of simulations of idealized Dansgaard-Oeschger or Antarctic Isotope Maximum events in a general circulation model. Year 0 is simply the beginning of the simulated event and is not displaying actual modern sea surface temperature data (i.e. year 0 is not today, 0 years before present). Not only is this a red herring, it is a completely misinterpreted red herring. They also repeat the favorite Antarctic cooling cherry, taking (and altering) a figure from Mayewski et al., (2017)2 which shows Antarctic-wide climate reanalysis temperature data. As a continent (larger than the US lower-48), Antarctica is not warming. This is because much of high, dry East Antarctica is not warming. However, important areas of Antarctica, including West Antarctica which likely would show about a 0.2ºC per decade warming trend over the reanalysis period (from 1979 to present, since satellites have given good data coverage). Climate is incredibly variable around Antarctica, and also through time (large interannual variability). This is well studied, but if you only look at one graph rather than reading the research papers you will not be aware of this. See: Nicolas andBromwich (2014)New Reconstruction of Antarctic Near-Surface Temperatures: Multidecadal Trends and Reliability of Global Reanalyses. Journal of Climate Bromwich et al (2012)Central West Antarctica among the most rapidly warming regions on Earth.Nature Geoscience 1-Markle et al., (2017) Global atmospheric teleconnections during Dansgaard–Oeschger events. NatureGeoscience 2-Mayewski et al., (2017)Ice core and climate reanalysis analogs to predict Antarctic and Southern Hemisphere climate changes.Quaternary Science Reviews Tyler Jones, Research Associate, University of Colorado The West Antarctica temperature plot that was pulled from my 2017 paper is very low resolution, and does not resolve the most recent few 100 yrs. We know from other studies that West Antarctica is currently warming faster than almost any other place on Earth. Furthermore, my paper has nothing to do with global warming or human activities. In fact, I only focus on time periods well before the Industrial Revolution. It is clear that global warming is caused predominantly by human activity. Belinda Dechnik, The University of Sydney My data does discuss sea surface temperaturein the Great Barrier Reef being slightly warmer than present during the mid-Holocene in response to natural climate variability. However, I in no way deny that the current climate is warming, and that anthropogenic effects are proving very detrimental, particularly to reef systems. This article has misunderstood my findings and in no way supports my view on climate change. I am very disturbed indeed that these people have used my article in such a way to try and discredit the serious effects of man-made climate change. Nathan Steiger, Postdoctoral Fellow, Columbia University The blog post [that the Breitbart article is based on] maliciously tampered with figures from my paper, removing lines from the figures. My paper is just not relevant to the arguments about global warming. Yair Rosenthal, Professor, Rutgers University The data were taken out of context. In fact a previous article (Rosenthal et al., 20013) made the argument that the current warming, as measured by the increase in Ocean Heat Content (OHC), is a reversal of the long-term cooling trend in the preceding centuries and the rate of heat gain is substantially higher than recorded in the past. If anything, these data support global warming as manifested by the recent increase in OHC. Bradley Markle, PhD Candidate, University of Washington My study, and almost all I saw mentioned in the blog post, are studies of climate change in the past. My study investigates connections between different parts of the climate system during climate events that happened over 10,000 years ago. Studying climate change in the past can give context to recent climate changes. However, my study in no way investigates or tries to attribute the causes of recent climate change. It does not deal with human influences on climate. I do not argue that “global warming… is a fake artefact [sic]”. The overwhelming scientific evidence is that the climate is currently changing and that human influences, primarily releasing CO2 into the atmosphere, have a significant impact. Though, again, this is not at all addressed in my study, nor any of the ones quoted that I recognized (though I did not read them all). The blog post and Breitbart article are both misleading and inaccurate, on several levels. David Reynolds, Postdoctoral Research Associate, Cardiff University (and co-authors) The article uses Figure 11 from Reynolds et al., 2017 without displaying the figure caption. The caption for this figure clearly states that the data shown have been detrended using a simple linear function in order to highlight the high-frequency (sub-centennial) mean annual sea surface temperature (SST) anomalies. This means we have statistically removed the long-term trend, i.e., the 20th century warming signal. The long-term trend was removed from the observational SST data as the particular proxy data being used for comparison, the marine bivalve growth increment width (GIW), does not record the low frequency change, such as the long-term warming trend. The reason the GIW chronology doesn’t record the long-term trend is because there are changes in the growth rates of the bivalves as they age (older=slower=thinner GIW). The standard procedure (e.g. Butler et al., 2009) for taking these so-called “ontogenetic effects” into account removes the ability of the GIW proxy to record long-term trends while retaining the signal of high-frequency variability. Looking at the non-detrended observational SST data (Fig 1) clearly shows there is a long-term warming trend over the 20th century in northeast Atlantic sea surface temperatures. Fig 1 — The black line shows mean annual sea surface temperatures over the North East Atlantic (50-60oN by 10-0oW). The dashed black line shows the linear trend over the 20th century. The data shown here are the raw data that were then linear detrended for use in Reynolds et al., 2017 Fig 11. Butler et al., (2009) Marine climate in the Irish Sea: analysis of a 489-year marine master chronology derived from growth increments in the shell of the clam Arctica islandica. Quaternary Science Reviews Matthias Thienemann, PhD Candidate, University of Cologne I do not agree with the Breitbart article that my study provides evidence against modern climate change caused by human activities. My paper deals with climate and environmental change on a larger timescale and does not allow any conclusions about current global warming. Florin Pendea, Associate Professor,Lakehead University Orillia The claim that our paper Pendea et al. (2017) published in the Quaternary Science Reviews brings support to the notion that anthropogenic global warming doesn’t exist is completely false. The story circulated by Breitbart news represents a gross misunderstanding of the data presented in our paper. The data we present constitutes a record of millennial-scale environmental change in the North Pacific that has no relevance to the discussion around the global warming trend observed during the last 150 years in a vast number of environmental archives around the world."
https://science.feedback.org/review/playing-semantics-misleading-breitbart-article-downplays-us-contribution-to-climate-change/,-2,"Breitbart, by Thomas D. Williams, on 2017-06-05.",,"""WHO: United States Among Least Polluting Nations on the Planet""",,,,,"This article at Breitbart argues that World Health Organization rankings of particulate matter air quality show that the United States is not one of the biggest polluters in the context of the Paris Agreement. Scientists who reviewed the article explain that this is misleading. Air quality is not an indication of national greenhouse gas emissions—and the United States is currently the second-largest emitter of carbon dioxide. This is true regardless of whether one uses the term “pollution” to describe carbon dioxide emissions.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Michael Brauer Professor, The University of British Columbia: The facts in the article are correct but the entire premise is deliberately misleading—it is correct that with respect to CONCENTRATIONS (i.e. the level is in the air) of one type of health-damaging air pollutant, the US is one of the countries with the lowest concentrations in the world. However, the Paris Accord is related to EMISSIONS (how much is released into the air) of climate-forcing pollutants and in that context the U.S. is among the countries in the world with both the highest overall emissions and the highest emissions per capita (higher than all other OECD countries). For climate change, EMISSIONS are what matters. Aimée Slangen Researcher, Royal Netherlands Institute for Sea Research (NIOZ): This whole post is based on semantics and basically one big strawman fallacy. The author is deliberately confusing air pollution from suspended particulate matter (as discussed in the WHO report) with pollution from carbon dioxide emissions (as discussed in the Reuters link and the Paris Agreement). Even though CO2 does not impact our health through “disease-causing pollutants that get into people’s lungs”, it does change our environment and the Earth’s climate, and in that sense does classify as a pollutant. Pierre Friedlingstein Professor, University of Exeter: Deliberately misleading about the role of CO2 and whether it is a pollutant or not, minimizing the role of CO2 as a greenhouse gas agent leading to climate change. Dan Jones Physical Oceanographer, British Antarctic Survey: Should we call carbon dioxide a “pollutant”? That question is relevant for policy, but either way, our choice of language does not change how physics behaves. When you add more carbon dioxide to Earth’s lower atmosphere, you get more energy at Earth’s surface. The extra energy added by human emissions of CO2 has to go somewhere; it isn’t going to just disappear. It ends up in the ocean, atmosphere, and cryosphere, affecting Earth’s climate system and putting us at risk for negative climate impacts (e.g. sea level rise, heat waves of increasing frequency and intensity, shifts in precipitation patterns). The author claims that this additional warming might actually be beneficial overall, which is inconsistent with the body of scientific literature on the topic (as always, see IPCC for summary). In short, this article makes a number of misleading statements and casually dismisses volumes of scientific evidence. Alexis Berg Research Associate, Harvard University: This article willingly confuses air pollution by particulate matter and greenhouse gas emissions. The article cherry-picks skeptic claims and out-of-context scientific evidence like deep-past CO2 atmospheric levels to try to make the case that CO2 emissions and climate change are not an issue. It tries to deny the fact that the US is a large climate change “polluter”, in the sense that it emits a lot of greenhouse gas per capita, by using the old, tired talking point that CO2 is not a pollutant, and that otherwise US air pollution is pretty low. Irrelevant and misleading.Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from the article; comments and replies are from the reviewers. 1. US cities generally do not have high concentrations of particulate matter in the air compared to other regions, but the United States currently emits more carbon dioxide than any other nation except China and is #1 in total emissions up to the present day. “Despite recent attempts to paint the United States as a major global polluter, according to the World Health Organization (WHO), the U.S. is among the cleanest nations on the planet.” Pierre Friedlingstein Professor, University of Exeter: This Breitbart article is playing with words, arguing that CO2 is not a “pollutant”. When it comes to CO2, the US is the second largest emitter after China. CO2 is a greenhouse gas, primarily responsible for climate change, inducing negative impacts on human and ecosystems. Replace the word “polluter” with “emitter” and the whole article falls apart—there is no story here. Chris Brierley Senior Lecturer, University College London: This presumes a strong link between the cleanliness of a country’s air and its own emissions. This does not necessarily hold. For example, the tiny papal state of the Vatican City is probably rather polluted (as it’s contained solely within the city of Rome). However, the vast majority of that pollution will have been emitted in Italy. “While France and other G7 countries lamented the U.S. exit from the Paris climate accord, America’s air is already cleaner than that of any other country in the G7, except Canada with its scant population.” Pierre Friedlingstein Professor, University of Exeter: The Breitbart author must know that the Paris Agreement is about climate change, not about air quality. “the WHO measures air pollution by the mean annual concentration of fine suspended particles of less than 2.5 microns in diameter. These are the particles that cause diseases of all sorts and are responsible for most deaths by air pollution. According to the WHO, exposure to particulate matter increases the risk of acute lower respiratory infection, chronic obstructive pulmonary disease, heart disease, stroke and lung cancer. The report […] found that the United States was one of the most pollution-free nations in the world.” Daniel Cohan Associate Professor, Rice University: The particulate matter (PM) discussion is essentially correct. PM is indeed thought to cause far more deaths than any other air pollutant. The United States indeed has lower PM2.5 levels than most other countries, especially when comparing cities. Most of the country outside California attains EPA’s 12 ug/m3 PM2.5 standard. “Most pollution-free” is poorly worded, since of course no populated area is ‘pollution-free’. But yes, PM2.5 levels in urban and rural areas of the United States are lower than those in corresponding areas of many other countries. The article misleads by conflating levels of air pollution with terminology like “most polluting” or “biggest polluters”. Relatively clean air quality in the United States does not negate the fact that we are the world’s second largest emitter of CO2. “With such relatively clean air throughout America, how can even reputable news agencies like Reuters continue spreading the well-worn lie that the United States is one of the ‘biggest polluters’ in the world?” Pierre Friedlingstein Professor, University of Exeter: Reuters is simply saying that in terms of CO2 emissions, China is the top emitter and the USA is second. There is no point denying this. It’s a fact, based on national fossil fuel production and consumption inventories. Whether you call CO2 “pollutant” or not is irrelevant. It is the main driver of climate change. Chris Brierley Senior Lecturer, University College London: America has the largest economy and the 3rd largest population on Earth. Even if each of its factories and people themselves emitted less than in most other countries, it would still add up to being one of the biggest polluters. Alexis Berg Research Associate, Harvard University: As the author pretends not to understand, this is the case if one considers greenhouse gas emissions as part of pollution. While China’s emissions grew tremendously over the last couple decades and it overtook the US as the largest total emitter a few years ago, the US is still one of the largest emitters per capita. In addition, historically, the US (and the EU) still own the largest share of cumulative emissions since the preindustrial era when emissions began. “While the United States must remain vigilant to keep the level of real, dangerous pollutants to a minimum, it may take some consolation in the fact that among G7 nations, it has the cleanest air of all.” Chris Brierley Senior Lecturer, University College London: Carbon dioxide is a well-mixed greenhouse gas—its concentrations are roughly 407 ppm everywhere across the globe. The national concentration bears absolutely no relevance to the country’s emissions. “The problem with this ploy is that carbon dioxide is not a pollutant and it is dishonest to say it is. CO2 is colorless, odorless and completely non-toxic. Plants depend on it to live and grow, and human beings draw some into their lungs with every breath they take to no ill effect whatsoever. Growers regularly pump CO2 into greenhouses, raising levels to three times that of the natural environment, to produce stronger, greener, healthier plants.” Pierre Friedlingstein Professor, University of Exeter: Again, the point is not “is CO2 a pollutant or not”. (I believe the Supreme Court said it is.) The point is: CO2 emissions in the atmosphere lead to climate change as CO2 is a greenhouse gas. Climate change has and will have negative impact on ecosystems (land and ocean). The author deliberately ignores this. Aimée Slangen Researcher, Royal Netherlands Institute for Sea Research (NIOZ): While the CO2 does not impact our health through “disease-causing pollutants that get into people’s lungs”, it does change our environment and the Earth’s climate, and in that sense it does classify as a pollutant. Richard Lindroth Vilas Distinguished Achievement Professor, University of Wisconsin-Madison: This statement is absolutely ridiculous. It violates the most basic, fundamental maxim of toxicology, first articulated by the Renaissance physician Paracelsus: “The dose makes the poison.” Or, “All things are poison and nothing is without poison; only the dose makes a thing not a poison.” In other words, just because a substance at one concentration is harmless does not mean it is harmless at another concentration. We don’t normally think of consumption of water as harmful to humans, but at high enough doses it will kill—and has done so. A pollutant is generally defined as a substance—artificial (synthetic) or natural—that occurs in the environment at least in part because of human activity, and that has a deleterious impact on living systems. Given that basic definition, there is no way that CO2 can not be a pollutant. It is produced by a variety of human activities, but principally burning of fossil fuels. Increases in its concentration are clearly linked to global warming, which has already, and increasingly will, negatively affect living systems, including humans. The only exit from this logic is to deny that CO2 leads to warming (in contradiction to massive scientific evidence) or to deny that warming negatively impacts living systems (again in contradiction to massive evidence). The authors use a classic rhetorical ploy to confound bits of information and draw erroneous conclusions. Yes, at low concentrations CO2 is not directly harmful to humans, and in fact is required by plants. And yes, small increases in CO2 have been shown to increase plant growth. (Some of my own work has shown such; such increases also shift the chemical composition of plant tissues, and not always for the better!). Plants grown under elevated CO2 do grow faster. To my knowledge, there is no evidence that they are “stronger” (whatever that means), and if anything, they are less green. Nor is there convincing evidence they are healthier. If anything, insects consume them more than ambient-CO2 plants. Alexis Berg Research Associate, Harvard University: This depends on the definition of “pollutant”. To the extent that CO2-induced global warming endangers human welfare and health, CO2 fits the Clean Air Act’s broad definition of “air pollutants”—that’s the reasoning behind the Supreme Court’s decision to let the EPA regulate CO2 emissions. Not that this is relevant to the definition of CO2 as a pollutant (which relies on it causing climate change), but the alleged total non-toxicity is not entirely true: there is some research* showing impairments in cognitive function test scores in people exposed to CO2 concentrations in the 950-1,000 ppm range, and even significantly worse performance when CO2 rose to 1500 and 2,500 ppm. Current atmospheric CO2 is around 400 ppm—possibly going up at least a few more hundred ppm this century without emission cuts—but concentrations greater than ~1000 ppm are often found in poorly ventilated rooms and buildings. Allen et al (2016) Associations of cognitive function scores with carbon dioxide, ventilation, and volatile organic compound exposures in office workers: a controlled exposure study of green and conventional office environments, Environmental Health Perspectives 2. Rising levels of carbon dioxide and other greenhouse gases result in climate change, which has significant negative impacts on humans and their environment. “Without human intervention, the concentration of CO2 has climbed as high as 7,000 parts per million (ppm) in prior eras, whereas at present the concentration is just over 400 ppm.” Pierre Friedlingstein Professor, University of Exeter: A CO2 concentration of 7000 ppm is a model estimate (not observations) for the Cambrian, about 500 million years ago. There are obviously no measures of temperature for that time, but estimates from models are about 10°C (18°F) warmer than present day! Not exactly reassuring news… Chris Brierley Senior Lecturer, University College London: But those worlds were rather different to those that humans inhabit. They had things like palm trees and crocodiles in the Arctic, and arguably land in the Tropics was completely sterile because of the heat. “Some experts, such as UN climate scientist Dr. Indur Goklany, have defended rising CO2 levels as a good thing for humanity. Goklany has argued that the rising level of carbon dioxide in the earth’s atmosphere ‘is currently net beneficial for both humanity and the biosphere generally.” Chris Brierley Senior Lecturer, University College London: I don’t believe that Dr. Goklany was ever employed or seconded to the UN. In fact, he would appear to be working for the climate-dismissing think tank, the Heartland Institute. Alexis Berg Research Associate, Harvard University: Technically, there is no such thing, really, as a UN climate scientist. There are climate scientists, worldwide, working for universities or national research organizations, and who contribute to the UN’s IPCC review process when it produces its report, every 7 years or so. Dr. Goklany is listed (Wikipedia) as working for the US Department of Interior as a science and technology policy analyst. His PhD is in electrical engineering, and beyond opinion pieces, he doesn’t seem to have published in the field of climate sciences. So I am not sure why his opinion is relevant at all—it goes without saying that it goes against the assessment of most of the scientific community working on climate change issues. Pierre Friedlingstein Professor, University of Exeter: Dr. Goklany is one of the very few defending that view. IPCC AR5* is very clear: “Continued emission of greenhouse gases will cause further warming and long-lasting changes in all components of the climate system, increasing the likelihood of severe, pervasive and irreversible impacts for people and ecosystems.” IPCC (2013) Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change"
https://science.feedback.org/review/paris-agreement-op-ed-us-senator-ted-cruz-misrepresents-costs-benefits-reducing-greenhouse-gas-emissions/,-2,"CNN, by Senator Ted Cruz, on 2017-05-29.",,"""Ted Cruz: Trump should withdraw from Paris climate pact""",,,,,"In an op-ed published by CNN, US Senator Ted Cruz (R-TX) argues for a US withdrawal from the Paris Agreement, an international agreement with the goal of reducing greenhouse gas emissions to limit global warming. Sen. Cruz’s argument is based on claims about the climate impact of cutting greenhouse gas emissions (which he says is limited) and the economic impacts of emissions reductions (which he says are dramatic). We asked researchers to evaluate whether these claims reflected the scientific state of knowledge on these topics. The reviewers indicated that Sen. Cruz’s article cites a single report that assessed only the costs of climate actions, relying on a series of assumptions that maximized those estimated costs, and that excluded the benefits of avoided climate change and of renewable sources of energy.See all the scientists’ annotations in context REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Frank Vöhringer Dr. rer. pol, Scientist, Ecole Polytechnique Fédérale de Lausanne (EPFL): This article is a statement of opinion which uses information and pseudo-information in a biased and misleading way. For example, the economic consequences of the Paris Agreement for the USA are hugely exaggerated. Gary Yohe Professor of Economics and Environmental Studies, Wesleyan University: The claims that the Paris Accord would only produce negligible benefits is just wrong—it is the start of an iterative response that minimizes the cost of meeting any long term goal like a 2 °C target. The jobs lost claim is just hyperbole and misdirection (e.g. the demand side is costing coal jobs—a trend that started before Obama became President and that will not be reversed by Presidential Orders that open more supply). Moreover, it ignores jobs created in alternative energy design, installation, and maintenance. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from the article; comments and replies are from the reviewers. 1. The United States’ pledged emissions reductions were one portion of the global actions that would significantly limit the magnitude of future warming. “This, all while doing nothing to meaningfully decrease global temperatures.” Gary Yohe Professor of Economics and Environmental Studies, Wesleyan University: [Comment taken from an evaluation of similar statements.] The statement about the climate impact of the Paris Agreement is incorrect. The figure below, appropriated from Fawcett et al (2015)*, displays the nuances of correctly projecting the impact of the Paris Accord through 2100. Business as usual creates an emission trajectory that rapidly passes by 80 gigatons of CO2 per year by 2070; the likelihood of seeing warming less than 3 °C through 2100 along this path is 10% with a median of more than 4 °C. Abiding by the Paris Accord through 2030 and continuing its momentum through 2100 would increase that likelihood to nearly 60% with a median somewhere around 2.5 °C – a reduction of approximately 1.5 °C and not 0.2 °C. Figure— Ranges of emissions scenarios with and without the Paris Accord through 2030 and beyond. The bars on the right indicate distributions of warming through 2100, and the trajectories show a no policy case as well as a modest policy, the Paris Accord extended, and an accelerated policy case. Source: Fawcett (2015) Fawcett et al (2015) Can Paris pledges avert severe climate change?, Science Valentina Bosetti Professor, Bocconi University: The Paris Climate Agreement alone will not solve the climate change problem (meaning we need even more action, not less). It puts us on the right track, though. See the Climate Action Tracker website for details. Figure —Expected emissions projections based on NDC commitments and current policies with corresponding temperature rise (right). Source: Climate Action Tracker 2. Research shows that reducing greenhouse gas emissions does not have to result in economic harm. And importantly, the impacts of climate change come with significant costs of their own. “According to a recent National Economic Research Associates Economic Consulting study, the Paris Agreement could obliterate $3 trillion of GDP, 6.5 million industrial sector jobs and $7,000 in per capita household income from the American economy by 2040. Meeting the 2025 emissions reduction target alone could subtract $250 billion from our GDP and eliminate 2.7 million jobs. The cement, iron and steel, and petroleum refining industries could see their production cut by 21% 19%, and 11% respectively.” Kenneth Gillingham Associate Professor, Yale University: It is true that this is what the NERA study says, with many caveats. However, this statement is misleading and taken out of context. There are three reasons for this. First, and most importantly, the NERA study looked at the costs of a hypothetical set of policy actions. These may not be the actions that will be taken to comply with the Paris Agreement. One could easily model other actions with much lower costs. Second, it is only the costs that are modeled. The benefits from avoiding climate change (sea level rise, greater storm surges, greater spread of diseases, etc.) are entirely ignored. The net costs from the policies would be entirely different and likely even positive. Third, there is some cherry-picking going on here. The NERA model is known to be inflexible in how it allows for innovation to influence economic activity, and thus it tends to provide much higher cost estimates than other well-known models such as the U.S. Department of Energy’s NEMS or ICF Consulting’s IPM. The NERA model provides useful information, but it is important for it to be taken in context of model results from other models and not cherry-picked as was done here. Valentina Bosetti Professor, Bocconi University: The claim on jobs lost is totally unsubstantiated by any scientific assessment. Depending on HOW we decide to decarbonize, the effect on jobs could be either positive or negative. In general, the large investments in infrastructure required might increase jobs. This is not accounting for the totally unrelated reduction in jobs that will be most likely materialize due to robots*. Acemoglu and Restrepo (2017) Robots and Jobs: Evidence from US Labor Markets, National Bureau of Economic Research Working Paper Gary Yohe Professor of Economics and Environmental Studies, Wesleyan University: [Comment taken from an evaluation of similar statements.] The numbers he quotes are from an analysis that adds new meaning to the term “business as usual”. They look to frame their vision of the future on the basis of static behavior across major sectors of the economy; i.e., they do not allow their sectors to adapt their business operations in response to changes in their economic environment. This allows the analysis to report prices for carbon that vary by orders of magnitude across 4 major sectors and leads them to expecting investment to fall by nearly 20% at a time when increasing investment in alternative energy and new production technologies would allow them to grow their profits and support more jobs. The reported losses in jobs, GDP, and personal income are the result of these rigid assumptions and not their similarly rigid depictions of how the US would implement its plan to meet its Paris Accord target. Rather than quote a different report from a different set of experts that show economic growth in both GDP and employment (though they exist, doing so would fall into the same ordering trap as the Senator), let’s look at the recent experience in the United States. The first figure below shows that US carbon emissions have fallen by 14% since 2006, a period of time during which the unemployment rate also fell from nearly 9% to around 4.4% and the annual rate of GDP growth climbed to the historically normal range of 1.5% to 2%. The second figure shows emissions falling in California by nearly 8% since 2008 partly in response to a cap and trade program that has generated $4billion in revenue—revenue that has been used to support investment in adaptation and simultaneous expansion of the employment of less carbon intensive and/or carbon free sources of energy at scale. Over the same period, California GDP has climbed by nearly 10%. These simple economic observations contradict the Senator’s claims. Energy related carbon emissions for the United States (1992-2012) Change in California GDP, population, and GHG emissions since 2000. Source: California Air Resources Board, 2015 Bob Ward,Policy and Communications Director, London School of Economics and Political Science: The National Economic Research Associates study assumes that the United States meets the 2025 target for reducing annual emissions of greenhouse gases, which is set out in its “nationally determined contribution”, and goes on to reduce its annual emissions by 80% by 2050 compared with 1990. The authors of the study admit on pages 10-11 to making the astonishing assumption that every other country in the world ignores the targets in their nationally determined contributions and make no further efforts to reduce emissions, so that much of the calculated costs to the United States economy subsequently arise from high-carbon companies relocate or lose business to competitors in other countries. The model assumes no increase in low-carbon electricity generation over the next four decades compared with the baseline scenario, so no increase in economic growth or jobs in the low-carbon sector and no substitution of low-carbon energy for high-carbon energy—emissions reductions are achieved by imposing very high carbon prices that reduce the consumption of coal and energy. The study makes the unrealistic assumption that there will be no economic benefits to the United States from avoided impacts of climate change or co-benefits from reducing local air pollution from fossil fuels which currently contributes to the premature deaths of 200,000 Americans each year, according to a study by the Massachusetts Institute of Technology*. Overall, this is an inaccurate and misleading assessment of the cost to the United States of participating in the Paris Agreement and honouring the commitments in its nationally determined contribution—indeed, the extreme assumptions mean this a study of the costs of policy-makers attempting to achieve emissions reduction targets in some of the least cost-effective ways available. Caiazzo et al (2013) Air pollution and early deaths in the United States. Part I: Quantifying the impact of major sectors in 2005, Atmospheric Environment “Not only would these unfair standards reduce American job growth and wages[…]” Kenneth Gillingham Associate Professor, Yale University: This is possible, but hard to defend based on the evidence known today. Regulations to reduce greenhouse gases would lead to a re-optimization in the economy. For example, there would be fewer jobs at coal power plants, but more jobs in renewable energy. Whether net jobs increase or decrease depends very much on the “job intensity” of services provided in these sectors. Most estimates suggest that the job intensity is higher for renewables than for fossil fuel plants and fossil fuel extraction. See the Bureau of Labor Statistics website for very solid (but somewhat dated) evidence on green jobs in the United States. “[…]and increase monthly utility costs for hardworking families” Kenneth Gillingham Associate Professor, Yale University: This is unlikely. Other modeled analyses, such as those for the Clean Power Plan, have shown that monthly utility costs would decline under action due to increased energy efficiency investments. See EPA’s regulatory impact analysis. “The coal industry alone supplies almost one-third of America’s electric power — with an increasing amount of clean coal-burning technology becoming available.” Kenneth Gillingham Associate Professor, Yale University: This is misleading. While coal burning has become cleaner due to regulations on the air pollutants it emits, it still emits copious amounts of carbon dioxide, which is a greenhouse gas. Carbon capture and sequestration technologies have proven to be expensive and troubled (For example, see this story in The New York Times). “The Clean Power Plan, a major component of fulfilling the agreement, would spike energy costs for working and middle-class Texans by 16% by 2030, according to the Economic Reliability Council of Texas” Kenneth Gillingham Associate Professor, Yale University: This statement is incorrect. It is true that the Economic Reliability Council of Texas states that energy PRICES will increase by 16% (not costs—prices). However, with the additional energy efficiency investments the Clean Power Plan would encourage, total energy costs are modeled to decline, rather than increase (see the EPA analysis). “We simply cannot afford an agreement that puts thousands of Americans out of work[…]” Kenneth Gillingham Associate Professor, Yale University: See above for why it is misleading to say that Americans would be put out of work. Some Americans would be put out of work, while new jobs would open up for others. On net, most evidence suggests that there would be job growth, rather than a decline in jobs. “[…]increases their energy costs[…]” Kenneth Gillingham Associate Professor, Yale University: This statement is misleading. If it said “increases energy prices,” it would be correct. But it says “increases energy costs,” which is incorrect because energy efficiency is expected to reduce energy costs on net. “[…]and devastates our core industries.” Kenneth Gillingham Associate Professor, Yale University: This is simply untrue. The costs would be relatively minor in most modeled estimates and the benefits have been shown to be greater than the costs. Again, see the EPA analysis."
https://science.feedback.org/review/natural-variability-can-not-explain-modern-global-warming-heartland-institute-report-claims/,Misleading,"Heartland Institute, Craig Idso, Fred Singer, Robert Carter, 2024-08-14",Neither the rate nor the magnitude of the reported late twentieth century surface warming (1979–2000) lay outside normal natural variability.,,"Misleading: The short timeframe given makes it more difficult to say whether something is or is not outside the bounds of natural variability. However, thorough analysis in the 2013 IPCC report concluded it was “extremely likely” (a probability of at least 95%) that humans are responsible for more than half of the warming since 1950, and likely all of it.",The warming experienced since the Industrial Revolution could not have been caused by natural factors. Human activity is primarily responsible for this (ongoing) change in climate.,Neither the rate nor the magnitude of the reported late twentieth century surface warming (1979–2000) lay outside normal natural variability.,,"Patrick Brown Assistant Professor, San Jose State University: The issue of whether or not a change in global temperature is outside the range of “normal natural variability” depends on the timescale being considered. It is true that some physical climate models (and some statistical climate models based on historically observed variability) indicate that it is possible for a warming episode as large as that seen from 1979-2000 to come about from unforced (internal) variability. However, when an unforced warming episode occurs, it is typically followed by an unforced cooling episode (if that wasn’t true, the climate would be fundamentally unstable and it would have run away to a snowball or hothouse state a long time ago). This means that the longer the sustained change in temperature, the less likely it is that the change could be due to “normal natural variability”. This is why the IPCC used a period almost 3 times longer in their attribution statement that “It is extremely likely that more than half of the observed increase in global average surface temperature from 1951 to 2010 was caused by the anthropogenic increase in greenhouse gas concentrations and other anthropogenic forcings together.” Overall this claim is misleading because you can always pick some subset of a forced warming/cooling episode and claim that the change in temperature over that particular time frame was not outside the range of natural variability. This would be like looking at a baseball player’s season in which he hit 100 home runs and claiming that nothing unusual was going on because it is possible for a typical player to hit 3-4 home runs in a single week. Peter deMenocal Professor, Lamont-Doherty Earth Observatory, Columbia University, and Director, Center for Climate and Life: This is a falsely constructed argument by limiting the time range to 1979 to 2000. One can cherry pick an interval and show that it’s not especially different from the past, however if one takes the full reliable record of the last 140 years the warming is unequivocal. Jeremy Fyke Postdoctoral researcher, Los Alamos National Laboratory: Exactly as deMenocal states above. Measurements over too-short intervals can be very unrepresentative of long-term trends. An extreme example: if I measured the rate of temperature change only in the evening I would very strongly claim that the Earth is always cooling. Conversely, my immediate neighbour could claim that the Earth was obviously always warming over the same period by taking measurements only in the morning. Of course, we disagree only because neither of us is measuring over a long-enough timeframe to capture an underlying temperature trend. Timothy Osborn Professor, University of East Anglia, and Director of Research, Climatic Research Unit: [This comment was made in response to a similar statement.] Taking into account uncertainties in the internal variability, in the strength of human and natural forcings and in the strength of the climate model simulations of the temperature response to these forcings, the best estimate is that all of the observed warming since 1950 is due to human influences. Because of the uncertainties, the human contribution could be larger or smaller than this, but it is “extremely unlikely” (defined by IPCC as less than 5% chance) that it is as low as only half the observed warming. IPCC (2013) Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change"
https://science.feedback.org/review/lull-solar-activity-little-effect-global-temperatures-claims-global-cooling-not-based-science/,Incorrect,"Heartland Institute, Craig Idso, Fred Singer, Robert Carter, 2024-08-14","Forward projections of solar cyclicity imply the next few decades may be marked by global cooling rather than warming, despite continuing CO2 emissions.",,"Incorrect: Even if solar activity does decline in the near future , the climate would continue to warm due to elevated greenhouse gas concentrations.  Inadequate support: No reference is provided for the claim that solar activity is projected to decline beyond other Heartland Institute publications.","It is difficult to project solar activity, but research shows that even a substantial lull in solar activity would be far too weak to counteract human-caused global warming.","Forward projections of solar cyclicity imply the next few decades may be marked by global cooling rather than warming, despite continuing CO2 emissions.",,"Georg Feulner Senior Scientist, Potsdam Institute for Climate Impact Research (PIK): Comment taken from two prior evaluations of similar statements. While there are some indicators that future solar activity might indeed be lower, this will have little effect on global temperatures. See, for example, this RealClimate post based on Feulner and Rahmstorf (2010)1. The results have been confirmed by a number of follow-up studies2-4. While regional and seasonal effects might be larger, the expected global temperature response to a future grand solar minimum similar to the Maunder Minimum is a cooling of about 0.1°C. It should be pointed out that this cooling would occur on the background of current anthropogenic warming which is about a factor of 10 larger[…] It is also clear from these numbers that a future grand solar minimum (which would last only for a few decades anyway) would not save us from global warming, as we have shown in a scientific paper* and explained inthis RealClimate post. The marginal temperature differences between warming scenarios with and without a future Maunder Minimum is illustrated here: Figure – Rise of global temperature for two different emission scenarios (A1B, red, and A2, magenta). The dashed lines show the slightly reduced warming in case a Maunder-like solar minimum should occur during the 21st century. The blue line represents global temperature data. Source: PIK. 1- Feulner and Rahmstorf (2010) On the effect of a new grand minimum of solar activity on the future climate on Earth, Geophysical Research Letters 2- Anet et al (2013) Impact of a potential 21st century “grand solar minimum” on surface temperatures and stratospheric ozone. Geophysical Research Letters [“although the solar minimum results in a reduced global warming, it cannot compensate continuing anthropogenic impacts.“] 3- Meehl (2013) Could a future “Grand Solar Minimum” like the Maunder Minimum stop global warming? Geophysical Research Letters [“a future grand solar minimum could slow down but not stop global warming.“] 4- Jones et al (2012) What influence will future solar activity changes over the 21st century have on projected global near-surface temperature changes?Journal of Geophysical Research Atmospheres. [“the possible mitigation potential for future solar activity changes is much smaller than the known uncertainties and ranges in the future anthropogenic response.“] Peter deMenocal Professor, Lamont-Doherty Earth Observatory, Columbia University, and Director, Center for Climate and Life: Forward projections of solar variability are fraught with deep uncertainties, as exemplified by the last solar minimum. Satellite observations show this to be the weakest solar cycle in over a century. The one thing we are nearly certain of is that the years ahead will see increasing carbon dioxide concentrations in the atmosphere due to increasing emissions if nothing is done to reverse course. We know carbon dioxide and methane are greenhouse gases that trap heat in the atmosphere. Jeremy Fyke Postdoctoral researcher, Los Alamos National Laboratory: The claim that the Earth may cool in coming decades due to solar variability is incorrect (even in the word “may”). It has no bearing in any climate science, model projections, or basic physical theory. The forcing from solar variability to the heat content of the Earth system is small relative to the accelerating forcing provided by human CO2 emissions."
https://science.feedback.org/review/global-warming-not-ceased-heartland-institute-report-falsely-claims/,Inaccurate,"Heartland Institute, Craig Idso, Fred Singer, Robert Carter, 2024-08-14",global warming ceased around the end of the twentieth century and was followed (since 1997) by 19 years of stable temperature,,"Factually Inaccurate: Global surface temperature have been the warmest on record over the past three years, in line with the global warming trend of the last several decades. Fails to grasp significance of observation: Because of natural variability, short-term periods of global surface temperatures cannot be assumed to always reflect the underlying long-term trend.","Global temperatures have continued to rise over the last few decades—notably in the oceans, which store over 90% of the excess heat trapped by the greenhouse gases humans have emitted. Over short intervals, temperatures may appear to increase slower or faster than the long term trend.","Model outputs published in successive IPCC reports since 1990 project a doubling of CO2 could cause warming of up to 6°C by 2100. Instead, global warming ceased around the end of the twentieth century and was followed (since 1997) by 19 years of stable temperature. Earth has not warmed significantly for the past 18 years despite an 8 percent increase in atmospheric CO2.",,"Ed Hawkins Principal Research Fellow, National Centre for Atmospheric Science: These statements are false. The IPCC has repeatedly assessed the warming due to a doubling of CO2 as between 1.5 or 2.0 °C to 4.5 °C. The warming by 2100 would be larger than this if the CO2 concentration in the atmosphere more than doubles by then. Global warming did not cease at the end of the twentieth century—the oceans, which absorb the vast majority of the additional heat trapped by greenhouse gases, have continued to warm during this time and surface temperatures have also risen, with 2014, 2015, and 2016 being the three warmest years on record. Eric Guilyardi CNRS Research Director, Université Pierre et Marie Curie & Professor, University of Reading: The range of warming for the “business as usual” scenario of the IPCC is 4 to 6 °C. A lower CO2 emissions scenario can lead to a warming which remains below 2 °C. There is no evidence to support the claim that global warming ceased. The observations compiled by the 3 main research groups (NOAA, NASA/GISS, UK Met Office/CRU) who provide estimates of surface global temperature all show continued warming. Source: NASA Natural “internal” variations occur on top of the “external” human-induced warming, leading to periods of slower warming and periods of accelerated warming. These variations are well understood by climate scientists. In the same way, Northern Hemisphere spring sees colder and warmer days (“internal” variations) superimposed onto the season’s warming due to increased “external” insolation. Human CO2 warms not only the surface but the full depth of the ocean. The natural variations exchange heat between the surface and the deeper ocean. Periods of slower surface warming correspond to periods of faster deeper ocean warming and vice-versa. Sea level height (which also reflects deeper ocean warming) has seen no slowdown, as expected from the continued CO2 emissions. Recent work has even shown an acceleration of sea level rise*. Source: NOAA Dieng et al (2017) New estimate of the current rate of sea level rise from a sea level budget approach, Geophysical Research Letters James Renwick Professor, Victoria University of Wellington: Global warming has continued uninterrupted and the last two years (2015 and 2016) are the first two to see 1 °C or more of warming compared to pre-industrial temperatures. Climate modelshave tracked this well. Daniel Swain Climate Scientist, University of California, Los Angeles: Eighteen years is generally too short an interval to quantify statistically significant climate trends; nevertheless, warming of both the Earth’s atmosphere and its oceans is apparent in observational data between 1998 and 2016. Ted Letcher Research Scientist, Cold Regions Research and Engineering Lab: Comparing the global temperature beginning at 1997 is a common trope used by some to discredit climate science. It is an intentional cherry picking of an anomalously warm year (big El Niño) to serve as the starting point. To convince yourself, start the trend at 1998, and you’ll get a much different answer. "
https://science.feedback.org/review/co2-greenhouse-gas-caused-warming-past-climate-changes-notably-feedback-amplifying-factors/,Flawed reasoning,"Heartland Institute, Craig Idso, Fred Singer, Robert Carter, 2024-08-14","Increases in atmospheric CO2 followed increases in temperature. Therefore, CO2 levels could not have forced temperatures to rise.",,"Flawed Reasoning: A lag between the initiation of past warming due to other factors and rising CO2 does not mean mean that CO2 cannot have caused temperature to increase further. Misrepresents a complex reality: CO2 has been shown to begin increasing before temperature in some instances of past climate change, but also acted as a feedback that amplified warming caused by other factors like cycles in Earth’s orbit.","Because of the physics of the transfer of electromagnetic radiation, CO2 acts as a greenhouse gas, meaning that temperatures must increase as the concentration of CO2 increases. This is true whether natural factors initiate warming (as in many past climate changes) and the release of CO2, or the warming is initiated by a release of CO2 (as humans have done).","Historically, increases in atmospheric CO2 followed increases in temperature, they did not precede them. Therefore, CO2 levels could not have forced temperatures to rise.",,"Christopher Colose Research Scientist, SciSpace LLC, NASA Goddard Institute for Space Studies: This is both false and irrelevant. Claims that “CO2 led temperature in the past, therefore cannot have caused it to rise” originated over a decade ago from a misrepresentation of ice core research (that itself has been subject to significant refinements in dating). It was based on the fallacy that since other factors influence climate (in this case, changes in the Earth-Sun geometry) and that the carbon cycle is affected by climate, the converse cannot be true. Of course, this is not logically coherent, and in practice is wrong since the radiative effect of CO2 is well-established. Indeed, CO2 would not be expected to fluctuate on its own 100,000 year timescale on its own, independent of the climate. In fact, more recent research* shows that CO2 still led global temperatures and the full deglacial process, unlike in older literature that examined only Antarctic sites. CO2 has also “led” global temperature on geologic timescales, and is largely responsible for how Earth’s temperature evolved over the last 50 million years. There are many ways to change the partitioning of carbon between the Earth and atmosphere, and how this happens is not relevant for the fact that if more CO2 is in the atmosphere, the planet will get warmer. Today, however, the excess source of carbon to the atmosphere is from humans. Shakun et al (2012) Global warming preceded by increasing carbon dioxide concentrations during the last deglaciation, Nature Lauren Simkins Assistant Professor, University of Virginia: This claim is flawed. Ice core records of past greenhouse gas and atmospheric temperature change1, coupled with records of ocean temperature and circulation changes2, indicate that there are complex feedbacks between earth-atmosphere-ocean changes that lead to naturally variable greenhouse gas changes. In some cases during past deglaciations, increases in CO2 have lagged methane (CH4) increases and associated atmospheric temperature rise, owing to natural processes that induce greenhouse gas release into the atmosphere. This is not the case for twentieth century and beyond human-induced atmospheric CO2 and temperature increases. Regardless of the source and cause of atmospheric CO2 increase, it will have a warming effect. Basic science does not change; CO2 is a greenhouse gas that is released into the atmosphere by burning of fossil fuels and leads to atmospheric warming. 1- Monnin et al (2001) Atmospheric CO2 Concentrations over the Last Glacial Termination, Nature 2- Skinner et al (2010) Ventilation of the Deep Southern Ocean and Deglacial CO2 Rise, Science Jeremy Fyke Postdoctoral researcher, Los Alamos National Laboratory: In the natural Earth system, CO2 release acted as a feedback of naturally-forced change (e.g. due to millennial-scale, gradual, changes in the Earth’s orbit). Thus, CO2 is clearly established as an important forcer of, for example, ice ages. This demonstrates it’s effectiveness as a radiative gas. Now, of course, the situation is flipped because humans are actively emitting CO2. This is why it is now a “forcer” rather than a “feedback”. This change in no way impacts our century-old understanding of how CO2 warms the climate."
https://science.feedback.org/review/new-york-times-series-accurately-describes-research-antarctic-ice-sheets-sea-level-rise-justin-gillis/,1.2,"The New York Times, by Justin Gillis, on 2017-05-18.",,"""Antarctic Dispatches: Miles of ice collapsing into the sea / Racing to find answers in the ice""",,,,,"This three-part article in the New York Times describes research on the outlook for Antarctica’s ice sheets and their contribution to sea level rise. Scientists who reviewed the article indicate that it is generally an accurate description of the state of research, which shows that the West Antarctic Ice Sheet (which is especially vulnerable to warming) alone has the potential to raise global sea level by several meters over the long term. However, several complex statements could be improved with additional context or more precise wording to help readers avoid misconceptions. For example, the article relies heavily on recent results from one ice sheet modeling effort that simulates higher future rates of ice melt, while other model simulations contain important differences.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Anders Damsgaard Postdoctoral Scholar, Geophysical Fluid Dynamics Laboratory, Princeton University: Generally scientifically sound, but caution should be displayed before basing discussion solely on a single modeling study, especially when it incorporates fundamentally different processes relative to other contemporary models. Benjamin Horton Professor, Earth Observatory of Singapore: Determining the rates, mechanisms, and geographic variability of sea-level change is vital to projecting future sea-level rise and managing coastal flood risks. Because the Greenland and Antarctic ice sheets have the largest potential to contribute to global mean sea-level rise under future warming, understanding their sensitivity to climate change is of particular importance. Jan Lenaerts Assistant Professor, University of Colorado, Boulder: This article is well written and contains no logical fallacies. Some statements could be clarified/quantified a bit better. Lauren Simkins Assistant Professor, University of Virginia: The Antarctic Ice Sheet has the potential to contribute significantly and rapidly to future sea-level rise. This article accurately and succinctly presents research on the processes and feedbacks that make the scientific community worried about the fate of the Antarctic Ice Sheet in a warming world. Richard Betts Professor, Met Office Hadley Centre & University of Exeter: The majority of the article is informative and a fair reflection of an important area of scientific research. It is good to inform readers of this. However, in my view, the start and end of the article and the headline give undue prominence to an highly speculative aspect of the story, i.e., the question of whether major loss of ice from Antarctica has already become unavoidable. This distinction between future, avoidable, risks and existing, unstoppable impacts is absolutely key, and while the majority of the article makes this distinction well, the emphasis in the headline and the start and end of the article are opposite to that in the main body of the article. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from the article; comments and replies are from the reviewers. 1.Studies of portions of the West Antarctic Ice Sheet—which is especially vulnerable to warming—show it’s possible that large losses of ice are already inevitable. “The acceleration is making some scientists fear that Antarctica’s ice sheet may have entered the early stages of an unstoppable disintegration.” Jeremy Fyke Postdoctoral researcher, Los Alamos National Laboratory: This is all factually true. Indeed, there is worry that a climatically-initiated dynamic disintegration is currently underway. However, there is also large uncertainty around whether this is the case. So, I would tend to classify scientific confidence on whether current mass change trends represent (in part) a true dynamical disintegration process as “low”. Jan Lenaerts Assistant Professor, University of Colorado, Boulder: This is true, but referring to West Antarctic ice sheet would be more precise. Richard Betts Professor, Met Office Hadley Centre & University of Exeter: It is clear that ongoing warming of the climate will pose major risks to the stability of ice sheets. However, this statement seems to have moved the story up a notch from what is actually written later in the article. There are two aspects to this: (1) the size of the area of concern (the whole of Antarctica rather than just parts), and (2) whether irreversible loss has already begun, as opposed to being an imminent risk. The article describes legitimate concerns that parts of the West Antarctic Ice Sheet are becoming vulnerable and hence may soon be at risk of starting an “unstoppable disintegration”, but the suggestion that this is actually already happening (and hence that major Antarctic ice loss is now avoidable) is far more speculative—as indeed the later parts of the article make clear. The phrase “entered the early stages of an unstoppable disintegration” is not the same as “becoming vulnerable to an unstoppable disintegration”, but the latter phrase would better represent what is said later in the article. “Because the collapse of vulnerable parts of the ice sheet could raise the sea level dramatically, the continued existence of the world’s great coastal cities — Miami, New York, Shanghai and many more — is tied to Antarctica’s fate.” Jan Lenaerts Assistant Professor, University of Colorado, Boulder: This is the prime motive of understanding Antarctic ice sheet dynamics, especially since the far-field location gives Antarctica relatively more weight to sea level rise along many Northern Hemisphere cities than Greenland. Lauren Simkins Assistant Professor, University of Virginia: The vulnerable parts of the ice sheet are those that resting on beds that are below sea level; therefore, the ice itself is in contact with a warming ocean. The majority of the West Antarctic and ~30% of the East Antarctic sectors of the ice sheet are grounded below sea level. “Remote as Antarctica may seem, every person in the world who gets into a car, eats a steak or boards an airplane is contributing to the emissions that put the frozen continent at risk. If those emissions continue unchecked and the world is allowed to heat up enough, scientists have no doubt that large parts of Antarctica will melt into the sea. But they do not know exactly what the trigger temperature might be, or whether the recent acceleration of the ice means that Earth has already reached it.” Jeremy Fyke Postdoctoral researcher, Los Alamos National Laboratory: This is factually true. In principle, there should be threshold in cumulative carbon emissions, beyond which the Earth system is committed to various levels of Antarctic ice loss. These thresholds have been only preliminarily explored, and are still largely unknown. And given the relatively slow response time of the Antarctic ice sheet, we may have already passes some/all of them—meaning that recent observed Antarctic changes reflect, in part, the initiation of large-scale, possibly irreversible, ice loss. “But as the ice age ended and the oceans warmed, all of them collapsed.” Timothy Osborn Professor, University of East Anglia, and Director of Research, Climatic Research Unit: “Collapse” is commonly taken to mean “fail suddenly and completely”, but in the context of ice sheets the scientific use of “collapse” can encompass much longer timescales (even multiple centuries) and it would be informative to make this clear. For example, IPCC AR5 WGI (Chapter 13 on sea level change) use it this way: “Future climate forcing could trigger such an unstable collapse, which may then continue independently of climate. This potential collapse might unfold over centuries for individual bedrock troughs in West Antarctica and sectors of East Antarctica.” Without this clarification, “collapse” may be misinterpreted to mean something happening over timescales of a single decade or much shorter timescales—especially when combined with earlier language about refugees “fleeing inland” due to a “rapid disintegration”. “The warmer water seems to be doing the most damage to a series of glaciers that flow into a region of West Antarctica called the Amundsen Sea. Satellites have identified the most rapid loss of ice there, raising a critical question: Has an unstoppable collapse of the ice sheet already begun?” Jeremy Fyke Postdoctoral researcher, Los Alamos National Laboratory: This is factually correct: this is a question that the research community is currently working hard to answer. “Already, scientists know enough to be concerned. About 120,000 years ago, before the last ice age, the planet went through a natural warm period, with temperatures similar to those expected in coming decades. The sea level was 20 to 30 feet higher than it is today, implying that the ice sheets in both Greenland and Antarctica must have partly disintegrated, a warning of what could occur in the relatively near future if the heating of the planet continues unchecked.” Timothy Osborn Professor, University of East Anglia, and Director of Research, Climatic Research Unit: Although factually correct, the information provided is not sufficient to convey the relevance of sea level during this previous warm period (the previous interglacial) to the current global warming situation. It is not directly analogous because of differences in the Earth’s orbit and the long timescale during which the ice sheet melt was exposed to the warmer temperatures. IPCC AR5 WGI Summary: for Policy Makers section B4 notes these two relevant issues: “This change in sea level occurred in the context of different orbital forcing and with high-latitude surface temperature, averaged over several thousand years, at least 2°C warmer than present”. IPCC (2013) Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change Jeremy Fyke Postdoctoral researcher, Los Alamos National Laboratory: This is factually correct. Indeed, past climate states analogous to the state which is expected to manifest in the near future, are characterized by much higher sea levels. This implies that the current Antarctic (and Greenland) ice sheet volumes are not consistent with warmer climate states. Rather, warmer climate states are consistent with smaller ice sheets. “Relatively near future” is probably a misleading statement in the text, because it implies to average people a decadal timeframe—almost certainly unrealistic for 20-30 ft of sea level rise. Anders Damsgaard Postdoctoral Scholar, Geophysical Fluid Dynamics Laboratory, Princeton University: Sea level and temperatures were higher in the previous interglacial, but the Earth climate system generally had a longer time frame to adjust to these conditions. 2. Floating ice shelves in front of Antarctic glaciers are affected by warming seawater. Ice shelves act as a stabilizing force for the ice on land, so their loss leads to greater loss of glacial ice. “The Ross shelf helps to slow the flow of land ice from Antarctica into the ocean. Compared with other parts of Antarctica, the shelf seems stable now, but computer forecasts suggest that it might be vulnerable to rapid collapse in the next few decades.” Lauren Simkins Assistant Professor, University of Virginia: Using the geological record of Antarctic Ice Sheet behavior, the Ross Ice Shelf has collapsed in the past1, likely in response to ocean and atmosphere warming. Therefore, we know that the Ross Ice Shelf, which currently protects large portion of the Antarctic Ice Sheet2, is susceptible to collapse. Yokoyama et al (2016) Widespread collapse of the Ross Ice Shelf during the late Holocene, PNAS Fürst et al (2016) The safety band of Antarctic ice shelves, Nature Climate Change “In the scientists’ worst-case computer simulations, continued global warming will cause the Ross Ice Shelf to weaken and collapse starting as early as the middle of this century.” Luke Trusel Assistant Professor, Pennsylvania State University: This collapse in the referenced work is initiated by strong surface melting causing ice shelf hydrofracture and then marine ice cliff instability. Other recent studies looking at the evolution of surface melt in Antarctica find far more modest (likely insignificant) increases in surface melt over this century, particularly over the Ross ice shelf. “Right now, the shelf works like a giant bottle-stopper that slows down ice trying to flow from the land into the sea. If it collapses, the ice could flow into the ocean more rapidly, an effect that has already happened on a much smaller scale in other areas of Antarctica. The most vulnerable parts of the West Antarctic ice sheet could raise the sea level by 10 to 15 feet, inundating many of the world’s coastal cities, though most scientists think that would take well over a century, or perhaps longer. They are worried about a possible rise of as much as six feet by the end of this century.” Timothy Osborn Professor, University of East Anglia, and Director of Research, Climatic Research Unit: This is correct but unclear. What is “perhaps longer” than “well over a century”? Given the importance of timescale for how coastal cities will respond to sea level rise, the range of possible timescales should be more explicit. IPCC AR5 WGI Chapter 13 on Sea Level Change assesses these as “sea level rise of 1 to 3 m per degree of warming is projected if the warming is sustained for several millennia (low confidence)”. IPCC (2013) Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change Margot Saher Lecturer, Bangor University, Wales, UK: Several glaciers that had previously been buttressed by the Larsen B ice shelf accelerated by a factor eight after said ice shelf disintegrated. The demise of this ice shelf lead to an increase of 27 km3 of ice loss per year*. Rignot et al (2004) Accelerated ice discharge from the Antarctic Peninsula following the collapse of Larsen B ice shelf, Geophysical Research Letters “But the story is not straightforward, and the warmer water attacking the ice has not been linked to global warming — at least not directly. The winds around the continent seem to be strengthening, stirring the ocean and bringing up a layer of warmer water that has most likely been there for centuries. Are those stronger winds tied to human-caused global warming? Some scientists think so, but others say the case is unproven. “We’re not sure because we don’t have enough data, for long enough, to separate signal from noise,” said Eric J. Steig, a scientist at the University of Washington who has studied temperature trends in Antarctica.” Jeremy Fyke Postdoctoral researcher, Los Alamos National Laboratory: This is factually correct, and an important point. In some climate analyses (such as global average air temperature), climate scientists and statisticians can (1) clearly detect a signal rising above the ‘background’ noise of natural climate variability and (2) clearly attribute this signal to human forcing (versus sun strength changes, volcanoes, cosmic rays, etc.). However, in the case of regional Antarctic climatology, this is not yet clearly the case. Particularly in the case of Antarctic oceanography, as Dr. Steig points out, this largely stems from lack of observations of sufficient length to allow for robust statistical detection/attribution of near-Antarctic ocean changes. 3. Researchers use computer model simulations to study the impacts of climate changes on ice sheets. Projecting the loss of glacial ice this century is complex, and the amount of sea level rise we can expect to see is somewhat uncertain—0.5 meters (20 inches) to as much as 1 or 2 meters (3.3-6.6 feet) given continued greenhouse gas emissions. “Recent computer forecasts suggest that if greenhouse gas emissions continue at a high level, parts of Antarctica could break up rapidly, causing the ocean to rise six feet or more by the end of this century. That is double the maximum increase that an international climate panel projected only four years ago. But those computer forecasts were described as crude even by the researchers who created them. ‘We could be decades too fast, or decades too slow,’said one of them, Robert M. DeConto of the University of Massachusetts, Amherst. ‘There are still some really big question marks about the trajectory of future climate around Antarctica.’” Benjamin Horton Professor, Earth Observatory of Singapore: Process-based predictions of sea-level rise by the International climate panel (i.e., the IPCC) are limited by uncertainties surrounding the response of the Greenland and West Antarctic ice sheets1, 2, 3, steric changes4, 5, contributions from mountain glaciers6, as well as from groundwater pumping for irrigation purposes and storage of water in reservoirs7, 8, 9. In large part because of the limitations of physical process models, IPCC AR5 does not offer “very likely” (5th to 95th percentile) sea-level projections, but concluded that “there is currently insufficient evidence to evaluate the probability of specific levels above the assessed likely range”10. The contribution from Greenland (GrIS) and Antarctic (AIS) Ice Sheet mass loss has increased since the early 1990s, comprising ~19% of the total observed rise in GMSL between 1993 and 2010 and ~40% of the total observed rise in GMSL between 2003 and 200811, 12. GrIS and AIS contributions are projected to become increasingly important over the 21st century10 and dominate sea-level rise uncertainty in the second half of the 21st century13, 14. 1- Pfeffer et al (2008) Kinematic Constraints on Glacier Contributions to 21st-Century Sea-Level Rise, Science 2- Pritchard et al (2012) Antarctic ice-sheet loss driven by basal melting of ice shelves, Nature 3- Rignot et al (2011) Acceleration of the contribution of the Greenland and Antarctic ice sheets to sea level rise, Geophysical Research Letters 4- Domingues et al (2008) Improved estimates of upper-ocean warming and multi-decadal sea-level rise, Nature 5- Marcelja (2010) The timescale and extent of thermal expansion of the global ocean due to climate change, Ocean Science 6- Raper and Braigthwaite (2009) Glacier volume response time and its links to climate and topography based on a conceptual model of glacier hypsometry, The Cryosphere 7- Konikow (2011) Contribution of global groundwater depletion since 1900 to sea-level rise, Geophysical Research Letters 8- Pokhrel et al (2012) Model estimates of sea-level change due to anthropogenic impacts on terrestrial water storage, Nature Geoscience 9- Wada et al (2012) Past and future contribution of global groundwater depletion to sea-level rise, Geophysical Research Letters 10- IPCC (2013) Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change 11- Cazenave et al (2009) Sea level budget over 2003–2008: A reevaluation from GRACE space gravimetry, satellite altimetry and Argo, Global and Planetary Change 12- Helm et al (2014) Elevation and elevation change of Greenland and Antarctica derived from CryoSat-2, The Cryosphere 13- Kopp et al (2014) Probabilistic 21st and 22nd century sea-level projections at a global network of tide-gauge sites, Earth’s Future 14- Cornford et al (2015) Century-scale simulations of the response of the West Antarctic Ice Sheet to a warming climate, The Cryosphere Jeremy Fyke Postdoctoral researcher, Los Alamos National Laboratory: I think this statement is also factually true. Indeed, recent simulations suggest that sea level rise from Antarctica could be very large. However, as is implied by the word “crude”, these state-of-the-art simulations are still lacking in important physical processes which are very difficult to implement at sufficient resolution in computer models of both the Antarctic Ice Sheet and near-Antarctic climate. So, due to these deficiencies, frankly there is still very large uncertainty regarding upcoming Antarctic change, at least as simulated by computer models. However, paleoclimate proxies have the ability to provide additional critical non-model-based constraints. Anders Damsgaard Postdoctoral Scholar, Geophysical Fluid Dynamics Laboratory, Princeton University: The “recent computer forecasts” referenced here likely refer to the numerical model developed by Rob DeConto1. Different from other ice-sheet models it includes the so-called “Marine Ice Cliff Instability”, which at present is not widely accepted in the ice-sheet modeling community. Including this instability will cause increased rates for resultant sea-level rise projections. On the other hand, DeConto’s model includes simplifications related to how ice sheet slides over the sediment at the base. This ice-sliding parameterization will generally increase ice-sheet stability and cause smaller projections of sea-level rise, as demonstrated in the Nature paper by C. Ritz et al. in 20152. There is still a lot of uncertainty regarding the physical and hydrological processes involved in ice-sheet modeling. Ideally, we prepare for the upper bounds regarding projected rates in sea-level rise, since the scientific community is still far from providing high-confidence estimates. DeConto and Pollard (2016) Contribution of Antarctica to past and future sea-level rise, Nature Ritz et al (2015) Potential sea-level rise from Antarctic ice-sheet instability constrained by observations, Nature Margot Saher Lecturer, Bangor University, Wales, UK: This is based on a combination of observations and modelling1. Observations show us several glaciers are in decline2 and ice shelves, which serve as a buttress for the glaciers, are thinning due to warmer sea water. This process is seen to be accelerating3. Where ice shelves (like Larsen B) have already vanished, glaciers in the hinterland have indeed sped up4. Numerical models predict that the changes underway now are likely to lead to a full-scale collapse of the west Antarctic Ice Sheet. 1- Joughin et al (2014) Marine Ice Sheet Collapse Potentially Under Way for the Thwaites Glacier Basin, West Antarctica, Science 2- Rignot et al (2011) Acceleration of the contribution of the Greenland and Antarctic ice sheets to sea level rise, Geophysical Research Letters 3- Paolo et al (2015) Volume loss from Antarctic ice shelves is accelerating, Science 4- Scambos et al (2004) Glacier acceleration and thinning after ice shelf collapse in the Larsen B embayment, Antarctica, Geophysical Research Letters Richard Betts Professor, Met Office Hadley Centre & University of Exeter: This reflects recent research—an important point is that this is about possible future consequences of high emissions, which are hence avoidable if emissions are lower. This is in contrast to the opening sentence and headline, which talk of “unstoppable disintegration” already in progress. “Incorporating recent advances in the understanding of how ice sheets might break apart, they found that both West Antarctica and some vulnerable parts of East Antarctica would go into an unstoppable collapse if the Earth continued to warm at a rapid pace. In their worst-case scenario, the sea level could rise by six feet by the end of this century, and the pace could pick up drastically in the 22nd century. Dr. DeConto and Dr. Pollard do not claim that this is a certainty — they acknowledge that their analysis is still rough — but they argue that the possibility should be taken seriously.” Jeremy Fyke Postdoctoral researcher, Los Alamos National Laboratory: This is factually true. I think the text is accurate in reflecting the distinct possibility of “upper-bound” Antarctic behaviour. However, note that the current “worst-case” scenario estimate is not the same as the current “most-likely” scenario estimate (in any risk assessment exercise). Anders Damsgaard Postdoctoral Scholar, Geophysical Fluid Dynamics Laboratory, Princeton University: Related to my earlier comment, the relevance of the “Marine Ice Cliff Instability” is still very unclear, and not generally accepted in the ice-sheet modeling community. DeConto and Pollard’s sea-level estimates certainly fall in the high end of sea-level rise projections. However, other processes such as non-linearities in melt or basal sliding may provide similar high-end estimates. “But some research suggests that a catastrophe might not yet be inevitable. In a study last year, Robert M. DeConto of the University of Massachusetts, Amherst, and David Pollard of Pennsylvania State University used their computer model to predict what would happen if emissions were reduced sharply over the next few decades, in line with international climate goals. Under the most ambitious scenarios, they found a strong likelihood that Antarctica would remain fairly stable.” Richard Betts Professor, Met Office Hadley Centre & University of Exeter: To my mind, the way this is written gives the impression that the DeConto and Pollard study is the outlier and that a substantial body of research suggest that a catastrophe is already inevitable—however, the article has not actually given any details of any such research, it only raised the possibility of unstoppable disintegration as a research question. It would be far more accurate to say that the vast majority of research does not suggest that a catastrophe is inevitable."
https://science.feedback.org/review/heartland-institute-reports-claim-climate-models-sensitive-co2-not-reflect-evidence/,Incorrect,"Heartland Institute, Craig Idso, Fred Singer, Robert Carter, 2024-08-14",[climate models] systematically over-estimate the sensitivity of climate to carbon dioxide ... and modelers exclude forcings and feedbacks that run counter to their mission,,"Unsupported: There is no evidence that climate models systematically overestimate the climate’s sensitivity to CO2. Rather, independent lines of research produces sensitivity estimates consistent with models.  Misrepresents the scientific process: Through research, scientists improve their understanding of the climate system, and this understanding is used to refine climate models as useful scientific tools. Science does not have a “mission” to reach a predetermined conclusion.",Climate models are based on physical processes and our understanding of how the climate system works. Their sensitivity to CO2 is in line with estimates based on modern observations and records of past climate changes.,"GCMs systematically over-estimate the sensitivity of climate to carbon dioxide (CO2), many known forcings and feedbacks are poorly modeled, and modelers exclude forcings and feedbacks that run counter to their mission to find a human influence on climate.",,"Reto Knutti Professor, ETH Zürich: The statement that climate models overestimate the warming in response to CO2 is incorrect; it is based on either too short time periods that are dominated by natural variability, by the comparison of models with datasets that do not have global coverage, by comparing to models that were run many years ago with emissions and forcings that differed from what actually happened, by the use of oversimplified energy balance models1, or a combination of it. Recent studies have shown that once the changes in climate feedbacks over time2, datasets with full coverage are considered3 and all forcings are considered, the agreement between predicted and observed warming is excellent, even over the recent hiatus period4. It is remarkable that even projections made decades ago with climate models that were much simpler (and were running on computers that were likely slower than a mobile phone today) were quite accurate5,6,7. 1- Knutti and Rugenstein (2015) Feedbacks, climate sensitivity and the limits of linear models, Philosophical Transactions of the Royal Society A 2- Armour (2017) Energy budget constraints on climate sensitivity in light of inconstant climate feedbacks, Nature Climate Change 3- Richardson et al (2016) Reconciled climate response estimates from climate models and the energy budget of Earth, Nature Climate Change 4- Medhaug et al (2017) Reconciling controversies about the ‘global warming hiatus’, Nature 5- Stouffer and Manabe (2017) Assessing temperature pattern projections made in 1989, Nature Climate Change 6- Fischer and Knutti (2016) Observed heavy precipitation increase confirms theory and early models, Nature Climate Change 7- Allen et al (2013) Test of a decadal climate forecast, Nature Geoscience Katrin Meissner Professor, University of New South Wales: False. Climate Sensitivity has been assessed by the community based on recent observations and proxy data from past climates. Climate models fall within this range of sensitivity. Some recent publications point to an increase in sensitivity with warmer temperatures*. Paleosens Project Members (2013) Making sense of palaeoclimate sensitivity, Nature Meraner et al (2013) Robust increase in equilibrium climate sensitivity under global warming,Geophysical Research Letters Zeebe (2013) Time-dependent climate sensitivity and the legacy of anthropogenic greenhouse gas emissions,Proceedings of the National Academy of Sciences Patrick Brown Assistant Professor, San Jose State University: This argument reached a peak in popularity around 2012/2013 when the “hiatus” was still ongoing (i.e. when the divergence between observed and modeled global temperature was at its largest). Even then, however, it was shown that you cannot conclude much about sensitivity to CO2 from such short-term fluctuations1. Similarly, Brown et al. (2015)2 showed that decade-long periods without warming are to be expected and that there was/is a 70% chance of seeing at least one 11-year period with no warming between the years of 1993-2050 under a “middle of the road” emissions scenario. Since then, observed warming has surged and, as of 2016, observations are warmer than the average prediction from climate models (see figures below). 1- Marotzke and Forster (2015) Forcing, feedback and internal variability in global temperature trends, Nature 2- Brown et al (2015) Comparing the model-simulated global warming signal to observations using empirical estimates of unforced noise, Scientific Reports Figure –Modeled global surface temperature(RCP 4.5 emissions scenario) compared toobserved temperature (NASA GISS). Source Figure – Updated version of IPCC AR5 Figure 11.25a, showing observations and the CMIP5 model projections relative to 1986-2005. The black lines represent observational datasets (HadCRUT4.5, Cowtan & Way, NASA GISTEMP, NOAA GlobalTemp, BEST). Source"
https://science.feedback.org/review/alaskas-vicious-cycle-warming-tundra-spews-co2-speeding-up-warming-joe-romm-think-progress/,0.3,"Think Progress, by Joe Romm, on 2017-05-16.",,"""The ‘ancient carbon’ of Alaska’s tundras is being released, starting a vicious warming cycle""",,,,,"This article at ThinkProgress by Joe Romm describes a study of carbon dioxide released from warming Alaskan tundra in recent years. While the article correctly notes the study’s conclusions, it also includes some language that is imprecise or extends beyond the contents of the study. Scientists who reviewed the story found that the article’s headline, in particular, carries a tone that exaggerates the study’s conclusions. One of the study’s authors also clarified that a personal quote used in the story (taken from a radio interview) requires context for clarity.See all the scientists’ annotations in contextUPDATE (19 May 2017): The ThinkProgress article has been edited, clarifying some of the statements highlighted here, including the title of the piece. Read moreREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Charles Koven Staff Scientist, Lawrence Berkeley National Lab: The writing is a bit over the top, but factually correct in general. The main weakness is in linking the solidly evidence-based observed changes from the Commane et al paper with much more speculative links such as the Siberian methane bubbles. Pierre Friedlingstein Professor, University of Exeter: The article departs significantly from the PNAS study it aims to cover. It’s catastrophic tone is not really supported by the study. David Archer Professor, University of Chicago: It’s true that Arctic permafrost contains lots of carbon and that this is vulnerable to decomposition in the coming few centuries. My only caveat to the reader would be that the amount of methane from the Arctic, and even the amount of CO2, are today much smaller than anthropogenic sources of those gases. The largest source of methane in the Arctic is the fossil fuel industry, but we never hear that. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-away: The statements quoted below are from the article; comments and replies are from the reviewers. Warming of the Arctic leads to thawing permafrost, which releases carbon that amplifies the warming—but this is not a runaway feedback. “The ‘ancient carbon’ of Alaska’s tundras is being released, starting a vicious warming cycle ‘This is ancient carbon, thousands and millions of years old.’ It’s being released ‘much earlier than we thought.” Pierre Friedlingstein Professor, University of Exeter: This is an interesting headline and quote. The article in PNAS uses atmospheric measurements of CO2 to derive sources and sinks from tundra and boreal forests. The study does not say that “this is ancient carbon, thousands and millions year old”… It could be, but there is no evidence for this in the paper. The paper only shows that atmospheric measurements indicate that Alaskan ecosystems have been a source of carbon in recent years (2012 to 2014). Charles Koven Staff Scientist, Lawrence Berkeley National Lab: Most of the carbon in the permafrost pool is thousands to tens of thousands year old at the oldest, rather than millions. “The Alaskan tundra is warming so quickly it has become a net emitter of carbon dioxide ahead of schedule, a new study finds” Pierre Friedlingstein Professor, University of Exeter: The study doesn’t really say that.The PNAS study itself focused on 3 years (2012-2014) for which aircraft measurements were taken from April to November, and finds that Alaskan tundra was a source of carbon for 2 of these 3 years (2012 is a small sink). Then these flux estimates are compared to data from CMIP5 models for those particular years. However, the PNAS paper does not assess when these CMIP5 models become sources of CO2. One would need to see long time series of the CMIP5 models, along with longer time series of aircraft measurements and inferred carbon fluxes to estimate when each turn from sink to sources. Because it’s getting warmer, there’s more CO2 coming out which means it’s going to get warmer which means there’s more CO2 coming out[…] And it will just run away with itself.” Pierre Friedlingstein Professor, University of Exeter: This is a simplistic description of a positive feedback. Yes, warming would lead to release of carbon from soils and permafrost, and this would lead to more warming, hence more carbon loss. But in no way would this lead to a runaway feedback. Say a warming of 1°C led to a release of carbon from soils that induces an additional warming of 0.1°C (that’s quite a large positive feedback: 10% of the initial perturbation). This additional 0.1°C would lead to an additional release of carbon, inducing an additional warming of 0.01°C, which will lead to more carbon released and an additional 0.001°C warming, etc… Ultimately, warming will be 1.111…°C—larger than the initial warming of 1°C but quite far from a runaway scenario. RóisínCommane,Research Associate, Harvard School of Engineering & Applied Sciences:(Dr Commane is the first author of the scientific study discussed in the ThinkProgress article) I spoke with Henry Fountain (New York Times), Chris Mooney (Washington Post), Oli Milman (Guardian), and Bob Berwyn (Inside Climate News) about the PNAS paper and I think they all did a great job condensing my attempts at communicating the message of the paper. The radio chat I did with a local NPR station in Juneau, AK (which I think is the source of this article) was probably the least comprehensive attempt—I tried to make things as simple as possible and didn’t realize that the quote would sound so off when taken outside of that context. I think the written articles better conveyed the essence of the paper compared to what I tried to say in the radio piece. “Melting permafrost can release not just CO2, but also methane, a much stronger heat-trapping gas.” Charles Koven Staff Scientist, Lawrence Berkeley National Lab: “Thawing” is a more accurate description than “melting” for what happens to frozen soil when you warm it. “‘We find that Alaska, overall, was a net source of carbon to the atmosphere during 2012–2014,’ the study concludes. Data from NOAA’s Barrow Alaska station ‘indicate that October through December emissions of CO2 from surrounding tundra increased by 73 percent since 1975, supporting the view that rising temperatures have made Arctic ecosystems a net source of CO2.’” Charles Koven Staff Scientist, Lawrence Berkeley National Lab: That’s a very accurate description of the study. Quite different from the headline. UPDATE (19 May 2017): Here is the list of statements that have been modified from the original version of the ThinkProgress article: UPDATE (21 May 2017): We have edited our review summary for precision. While it initially read “it also includes some language that is misleading”, we changed the word “misleading” to “imprecise”, which better describes the issue scientists had with this piece—some sloppiness in the precision of concepts used."
https://science.feedback.org/review/heartland-institute-report-incorrectly-claims-no-evidence-human-impacts-melting-ice/,Incorrect,"Heartland Institute, Craig Idso, Fred Singer, Robert Carter, 2024-08-14",Melting of Arctic sea ice and polar icecaps is not occurring at ‘unnatural’ rates and does not constitute evidence of a human impact on the climate.,,"Incorrect: Observed Arctic sea ice loss, and mass loss from the Greenland and Antarctic ice sheets, is not explained by natural variability alone. Research indicates that human activity has made a significant contribution to the loss of glacial ice and Arctic sea ice.",The rapid loss of glacial ice and Arctic sea ice cover is consistent with and most likely due to human impact on the climate system.,Melting of Arctic sea ice and polar icecaps is not occurring at ‘unnatural’ rates and does not constitute evidence of a human impact on the climate.,,"Jan Lenaerts Assistant Professor, University of Colorado, Boulder: This is a mostly false statement. The correct part is the East Antarctic ice sheet is close to mass balance1, 2and that the recent changes in Antarctic sea ice cover are explained by natural variability3, 4. The statement is definitely false for Arctic sea ice, which is decreasing dramatically since the 1990s as a response to human greenhouse gas emissions. In fact, there is a direct and linear relation between CO2 emitted and sea ice decline: each metric ton CO2 emitted leads to a 3 m2 loss of Arctic sea ice5. The current loss of sea ice falls outside of natural variability and has been unprecedented in at least the last 1,450 years6. West Antarctic mass loss has been rapidly increasing since the 1990s2. Glacial retreat in the Amundsen Sea region, the main driver of this mass loss, appears to have started already in the early 20th century7. The rate of retreat is rapid and widespread8, with no mechanism for future stabilisation9. Current ice sheet mass loss contributes significantly (almost 40%10) to observed 21st century sea level rise. Until 2016, Arctic sea ice loss has dominated over slight Antarctic sea ice gain. In 2016 and 2017, Antarctic sea ice has been in decline as well, and reasons for this are currently under study. 1- Shepherd et al (2012) A Reconciled Estimate of Ice-Sheet Mass Balance, Science 2- Gardner et al (2017) Increased West Antarctic ice discharge and East Antarctic stability over the last seven years, The Cryosphere Discussions 3- Turner et al (2016) Antarctic sea ice increase consistent with intrinsic variability of the Amundsen Sea Low, Climate Dynamics 4- Meehl et al (2016) Antarctic sea-ice expansion between 2000 and 2014 driven by tropical Pacific decadal climate variability, Nature Geoscience 5- Notz and Stroeve (2016) Observed Arctic sea-ice loss directly follows anthropogenic CO2 emission, Science 6- Kinnard et al (2011) Reconstructed changes in Arctic sea ice over the past 1,450 years, Nature 7- Smith et al (2017) Sub-ice-shelf sediments record history of twentieth-century retreat of Pine Island Glacier, Nature 8- Rignot et al (2014) Widespread, rapid grounding line retreat of Pine Island, Thwaites, Smith, and Kohler glaciers, West Antarctica, from 1992 to 2011, Geophysical Research Letters 9- Joughin et al (2014) Marine ice sheet collapse potentially under way for the Thwaites Glacier Basin, West Antarctica, Science 10- Rietbroek et al (2016) Revisiting the contemporary sea-level budget on global and regional scales, PNAS Mouginot et al (2014) Sustained increase in ice discharge from the Amundsen Sea Embayment, West Antarctica, from 1973 to 2013, Geophysical Research Letters Jeremy Fyke Postdoctoral researcher, Los Alamos National Laboratory: This is demonstrably false, and indicates an ignorance of a large body of existing and easy-to-access literature, based on a wide range of independent direct observations and modeling. Both ice sheets (Greenland and Antarctica) are exhibiting mass loss, including collapse of features such as large ice shelves that have been present for millennia. Negative Arctic sea ice trends are clearly emerging from the background of natural variability. Antarctic sea ice, just this year, exhibited an unprecedented decrease, well outside of established recent natural variability windows. Peter deMenocal Professor, Lamont-Doherty Earth Observatory, Columbia University, and Director, Center for Climate and Life: The Arctic is a canary in the coal mine, and the rapid changes there reflect the telltale polar amplification signature of increased greenhouse gas forcing. The rates of Arctic sea ice retreat are unprecedented compared to earlier decades and this is one of the fastest moving systems on the planet. Both polar ice caps are losing mass as shown by GRACE satellite data. A recent study* suggests that as much as 60 % of the observed loss in late-summer Arctic sea ice extent could have been caused by changes in atmospheric circulation patterns – i.e., natural causes. Natural factors can only explain a part of the observed losses, and multiple studies (reviewed in the latest IPCC report) have shown that it is not possible to explain the observed losses without considering non-natural factors. Ding et al (2017) Influence of high-latitude atmospheric circulation changes on summertime Arctic sea ice. Nature Climate Change Jennifer Francis Senior Scientist, Woods Hole Research Center: The extent of Arctic sea ice is far lower than at any time in the past 1450 years (Kinnard et al 2011), and there is no viable explanation for its disappearance other than the rapid increase in heat-trapping greenhouse gases owing to human activities. Kinnard et al (2011) Reconstructed changes in Arctic sea ice over the past 1,450 years, Nature "
https://science.feedback.org/review/global-quackery-earth-not-warmed-past-19-years-new-study-finds-joseph-curl-the-daily-wire/,-2,"The Daily Wire, by Joseph Curl, on 2017-05-08.",,"""Global Quackery: Earth Has Not Warmed For Past 19 Years, New Study Finds""",,,,,"The title of this Daily Wire article inaccurately claims that global temperature has not warmed over the past 19 years—in direct contradiction with observations—and the article provides no evidence in support of this bold claim. The article relies, for its first section, on a Telegraph article (analyzed separately here) that is flawed and itself based on claims from a blog post referring to data from the Danish Meteorological Institute (DMI). But DMI scientists explain that the article “fundamentally misrepresents both our research and the operational data products we provide”. The second section quotes an article in the UK tabloid Daily Star. It claims that an imminent ice age is coming, based on a misrepresentation of the Sun’s influence on the climate that we have already covered in an earlier Climate Feedback review: In that review, Prof. Michael Lockwood explained, “The whole argument rests on the incorrect myth that the Maunder minimum caused a ‘mini ice age’ and uses that name to draw specious implications and conclusions.” Georg Feulner also noted that “the scientists mentioned in the article have not predicted a ‘mini ice-age’, but an extended period of low solar activity similar to the 17th-century Maunder Minimum. The Maunder Minimum falls into a more extended period of somewhat cooler climate conditions termed the ‘Little Ice Age’ (although this was no true ‘ice age’). It has thus become rather fashionable to claim that the ‘Little Ice Age’ was caused by low solar activity, but this is not what the science says.”See all the scientists’ annotations in context This is part of a series of reviews of 2017’s most popular climate stories on social media.UPDATE (16 May 2017): Following this analysis, the Daily Wire edited its article. Most notably, a statement describing the misleading claims from the Telegraph article as “findings of the DMI” has been removed. However, the misleading claims in the article generally stand uncorrected. Read moreREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. William Anderegg Associate Professor, University of Utah: The article is full of misleading claims, factual inaccuracies, and lack of documentation for many of its claims. Georg Feulner Senior Scientist, Potsdam Institute for Climate Impact Research (PIK): The article contains major inaccuracies and gives a highly biased viewpoint not supported by scientific evidence. Daniel Swain Climate Scientist, University of California, Los Angeles: While there are relatively few quantitative (and scientifically assessable) claims in this piece, those that are present are categorically false. This piece draws heavily upon a recent article in The Telegraph that itself is filled with fundamental factual errors and willful misinterpretation of data. Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: The article contains little to no rational treatment of observational data, but relies on heavily biased secondhand interpretation. It has been written by someone who had no intention of researching the truthfulness of arguments that others have made, and merely reproduces their mistruths with added inflammatory language and chiding outrage. It rehashes logically-flawed and cherry-picked arguments from other articles and repeats them verbatim without questioning their authenticity. The article also rallies emotively against ‘Global Quackery’ from thousands of qualified climate scientists of all political persuasions, but then cites factually-inaccurate statements from the CEO of a dubious company as opinions of a ‘scientist’ and ‘expert’, without any question of their integrity. Even the title is based on a lie. There is no ‘study’ that finds static temperatures for 19-years. This article is based on a newspaper article that makes this false statement based in turn on a blog post. This blog post in turn willfully misinterprets data that has been made publicly-available from the Danish Meteorological Institute. In no point along this production line of mistruths was anything like a peer reviewed study involved.Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from the article; comments and replies are from the reviewers. 1. There is a long-term warming trend at both the global scale and in the Arctic, which experienced its second-warmest winter on record in 2016/2017. “ever since December temperatures in the Arctic have consistently been lower than minus 20 C” Daniel Swain Climate Scientist, University of California, Los Angeles: It is indeed true that the Arctic is cold in winter—it’s hard to argue with that. But this statement belies the fact that winter 2017 was actually extraordinarily warm by historical standards, and second only to the record-shattering warmth observed just last year (in 2016). The attached plot, created by Zachary Labe and available at http://sites.uci.edu/zlabe/arctic-temperatures, shows that the -20 °C temperatures this winter are nearly 10 °C degrees above the long-term average of -30 °C! Therefore, the fact that temperatures were -20 °C this winter in the Arctic is actually a testament to just how much the Arctic has warmed in recent years. Ruth Mottram, Martin Stendel, Peter Langen, Danish Meteorological Institute This statement is both wrong and misleading. Firstly, most of the Arctic has in fact been consistently warmer than -20 °C this winter. For the period 1 December 2016 to 20 April 2017, the average temperature was above -20 °C everywhere in the central Arctic except north of Greenland and the Canadian Archipelago. Over the Greenland Ice Sheet and in Eastern Siberia (and only there), the temperature was below -25 °C. Secondly, it should not be a surprise that the Arctic is very cold in winter (a period with little to no sunlight). It is much fairer to consider the difference between this winter and the average winter temperatures. Compared to our baseline of 2004-2013 everywhere in the Arctic region was at least 4 °C warmer than the average of 2004-2013 (in itself a warmer baseline period than the 1958-2002 baseline used elsewhere). Around Svalbard, it was about 4.5 °C warmer than average and in Northern Greenland, including Kap Morris Jesup, the world’s northernmost weather station (where a record +3 °C temperature was recorded on one day in February), Ellesmere Island in northeastern Canada, and large parts of eastern Siberia this winter were more than 5 °C warmer than the average as you can see below: Figure: Left, Average temperature over the Arctic for the period December 2016 to April 2017; Right, Deviation of temperature for the period December 2016 to April 2017 from the average 2004-2013.This makes the winter 2016/2017 the second warmest on record in the Arctic (after winter 2015-16), according to the European Copernicus climate service.“record temperatures brought in 2016 by an exceptionally strong El Niño” Andrew King Research fellow, University of Melbourne: Last year the annual global temperature was about 1.1 °C above a late-19th century baseline but only about 0.1°C of this was due to the El Niño—the other 1 °C is due to human influences. So while the record occurred in 2016 due to El Niño, most of the anomaly was due to climate change. “the satellites now show that in recent months global temperatures have plummeted by more that [sic] 0.6 degrees” Daniel Swain Climate Scientist, University of California, Los Angeles: El Niño events do indeed elevate global temperatures temporarily, and this is partly why global temperatures in 2016 were so extreme. But as the attached plot from NASA GISS shows, temperatures so far in 2017 have still been extraordinarily warm in a historical context, and in fact would have been record-breaking if not for the large temperature spike that occurred in 2016. In any case, it is not scientifically meaningful to measure global temperature “trends” over a two year period; the large and statistically significant long-term warming signal overwhelms short-term variations on multi-decadal timescales. William Anderegg Associate Professor, University of Utah: While true (and not necessarily in agreement with the more robust thermometer records for this period, this has no bearing on the long-term climate trend, which is driven by human emissions of greenhouse gases. It is misleading and a logical fallacy to claim this says anything about climate change, which is the long-term change in temperatures. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: While temperatures have declined modestly from the peak of the El Niño event, this is expected behavior, particularly in satellite records where El Niño is amplified. However, temperatures in January through April are quite above average to-date, and while we may not set a record temperature in 2017 compared to 2016, it will very likely be the second warmest year on record (at least on the surface). Through present there is no sign of any sort of pause or slowdown in any of the surface records or one of the two satellite records (the RSS groups latest version 4 record). The only record showing a continued pause is the one produced by the University of Alabama, Huntsville (the UAH record). The differences between these records and their causes is an area of active research, though we have strong reason to suspect that the surface record is quite accurate. “This means the global temperature trend has now shown no further warming for 19 years” Andrew King Research fellow, University of Melbourne: This is both cherry-picking of the data (starting with 1998), and not correct anyway. William Anderegg Associate Professor, University of Utah: This is blatantly false. Examine the trend here: Furthermore, a short time period of a few months in 2017 cannot say anything whatsoever about the long-term change in climate. Andreas Schmittner Associate Professor, Oregon State University: This statement is false. Global temperatures continue their long-term warming trend. 2. Warming in the Arctic is causing changes to the cryosphere: both sea ice and land ice (on Greenland) have been melting faster in recent years. “Arctic sea ice is thicker than ever” Alek Petty Postdoctoral associate, NASA Goddard Space Flight Center: PIOMAS (a model constrained by surface temp observations) shows the ice volume tracking lower than ever for this time of the year. Most recent direct observations show the sea ice is still a lot thinner than it was in previous decades. Georg Feulner Senior Scientist, Potsdam Institute for Climate Impact Research (PIK): This is wrong. Arctic sea-ice thickness in 2017 is actually at its lowest values compared to earlier years for which we have sufficient data coverage, see: “In April the extent of Arctic sea ice was back to where it was in April 13 years ago” Ed Hawkins Principal Research Fellow, National Centre for Atmospheric Science: In the NSIDC dataset, April 2017 was actually the equal of the lowest Northern Hemisphere extent on record (tied with 2016 on 13.83 M km2). Ruth Mottram, Martin Stendel, Peter Langen, Danish Meteorological Institute This statement is misleading. Arctic sea ice extent in April was significantly lower than the long-term average—but varies substantially from day to day and year to year as processes such as wind and waves and short-term weather variability have a substantial effect on sea ice extent, particularly at this time of year. However, over the long term since 1979, the April sea ice extent has declined by around 3% per decade, at other times of the year the decline is even more marked. This is an example of cherry-picking dates in order to try and state that the sea ice is recovering (it’s not). It also confuses climate variability with trends over short periods. “Furthermore, whereas in 2008 most of the ice was extremely thin, this year most has been at least two metres thick.” Daniel Swain Climate Scientist, University of California, Los Angeles: Arctic sea ice volume has actually exhibited record thinness so far during 2017—beating the previous record years of 2012/2016 by a wide margin. Another nice visualization by Zachary Labe illustrates this quite clearly: “Whereas in 2008 most of the ice was extremely thin, this year most has been at least two metres thick.” Ruth Mottram, Martin Stendel, Peter Langen, Danish Meteorological Institute This is a misleading statement, as “extremely thin” is not defined and what is also not stated is that there were also substantial areas of much thicker ice in 2008. If we look at the total ice volume, which averages these effects out, on 1st May 2017 it was about 6% lower than the ice volume for the same date in 2008 according to the operational ocean and sea ice model. Again, in addition to air and ocean temperature, ice thickness depends on winds and ocean currents and shows large variations from year to year so choosing two years arbitrarily is misleading without considering the long term trend. “The Greenland ice cap last winter increased in volume faster than at any time for years.” Jan Lenaerts Assistant Professor, University of Colorado, Boulder: This is not per se completely incorrect, but the author does not tell us the whole story. The author refers to the growing of the ice sheet volume through snowfall throughout winter. The snow accumulated on Greenland in past winter (September-April) has indeed been remarkably high: However, this does not imply that the volume of the ice sheet is increasing, because (1) the ice sheet also loses ice through discharging icebergs; it is the difference between snowfall-driven growth and solid ice discharge that determines if the ice sheet gains or loses volume, and (2) the snow that accumulated during the winter will (at least partly) melt over the summer. That’s why we analyse changes to the ice sheet volume/mass on (at least) annual time scales. Only after the summer we will know how much of the accumulated snow has (not) been melted. uring the past years, the amount of melting has been record-high, and much of snow that accumulated over the winter melted and ran off into the ocean. Concurrently, ice discharge continued, so the Greenland ice sheet LOST considerable volume. We will know in September how much the ice sheet has changed volume this year. Two additional remarks: (a) The word “faster” should not have been used here. We are not talking about the rate of speed, but rather about the total change in volume. Also, it is easier to talk about “mass changes” than “volume changes” since the former is not sensitive to the density of the medium we are talking about (snow has a lower density than ice!). (b) The enhanced snowfall, ironically, is most probably also a signal of the strongly warming Arctic: as the atmosphere warms, it contains more moisture, and generates more precipitation. Also, record-low fall and winter sea ice extent led to large streaks of open water that might have contributed to additional moisture loading of the air. Ruth Mottram, Martin Stendel, Peter Langen, Danish Meteorological Institute Here the author confuses short-term variability (i.e., weather) with a significant change to the Greenland ice sheet. Until a full annual cycle is considered, it is impossible to say if the volume is increasing or not. We can confirm that there has been a record amount of snow and rain over Greenland this winter, most of it fell in October due to extra-tropical hurricane Nicole. However this “extra” winter snowfall is not yet part of the Greenland ice sheet but a snow layer sitting on top of it and the extra gain in snow may be easily wiped out by a warm sunny summer. The summer is by far the most important time of year for the ice sheet—it determines if the ice sheet will grow or shrink so we will not know until September if this winter’s extra snow will have any effect on the overall ice sheet mass budget. Furthermore, we should bear in mind that extra snowfall in Greenland is actually predicted in most climate models, (a warmer atmosphere = more moisture = more snowfall in Greenland) as a consequence of climate change. We should also note that almost all of the additional above average snow fell in the East and South, and north-western Greenland actually has less snow than usual (which you can see in the figure above). 3.Solar activity is expected to only have a minor influence on future temperature. Claims of a “little ice age” coming are based on misrepresentation of scientists’ work and a misunderstanding of the consequences of a solar activity minimum. “Scientists are also expecting a ‘huge reduction’ in solar activity for 33 years between 2020 and 2053 that will cause thermometers to crash.” Georg Feulner Senior Scientist, Potsdam Institute for Climate Impact Research (PIK): Solar activity cannot be predicted. While there are some indicators that future solar activity might indeed be lower, this will have little effect on global temperatures. See, for example,this RealClimate post based on Feulner and Rahmstorf (2010)*. The results have been confirmed by a number of follow-up studies. Feulner and Rahmstorf (2010) On the effect of a new grand minimum of solar activity on the future climate on Earth, Geophysical Research Letters Rasmus Benestad Senior scientist, The Norwegian Meteorological institute: This statement about future solar activity levels between 2020-2050 is completely baseless. Only a few years ago, the scientists were surprised by the recent reduction in the current activity. “He said: ‘We have had five warming cycles since about 900AD, each followed by a dramatic cooling cycle.’” Georg Feulner Senior Scientist, Potsdam Institute for Climate Impact Research (PIK): The global (or even hemispheric) temperature drops during past grand solar minima were actually small. Furthermore, there is increasing evidence that slightly cooler episodes like the “Little Ice Age” were predominantly caused by volcanic eruptions. See, for example,this summaryof Miller et al (2012)*. Miller et al (2012) Abrupt onset of the Little Ice Age triggered by volcanism and sustained by sea-ice/ocean feedbacks, Geophysical Research Letters"
https://science.feedback.org/review/another-arctic-ice-panic-world-temperatures-plummet-the-telegraph-christopher-booker/,-2,"The Telegraph, by Christopher Booker, on 2017-05-06.",,"""Another Arctic ice panic over as world temperatures plummet""",,,,,"The Telegraph published a brief article by Christopher Booker discussing recent Arctic temperatures and sea ice cover in the context of climate change. It is largely based on claims made in a blog post that refers to data from the Danish Meteorological Institute (DMI). But DMI scientists explain that the article “fundamentally misrepresents both our research and the operational data products we provide”. The scientists who have reviewed the article indicate that its claims are misleading or inaccurate. For instance, the article emphasizes that global average temperature has decreased since the end of the 2016 El Niño event, which was expected, but fails to note that this recent decrease by no means reverses the long-term increase in temperature. It also inaccurately claims that global temperature has not warmed over the past 19 years—in direct contradiction with observations. The author claims that last winter in the Arctic was “cold” (-20°C), but fails to recognize that this temperature is much warmer than the norm for the Arctic (by about 5°C), making it the second warmest winter on record. [This article has been used as a reference by another article in the Daily Wire, which expands on false claims made in this Telegraph article.] See all the scientists’ annotations in contextGUEST COMMENTS: Ruth Mottram, Martin Stendel, Peter Langen, Danish Meteorological Institute (with contributions from Mads Ribergaard and Gorm Dybkjær) The articles in The Telegraph and The Daily Wire fundamentally misrepresent both our research and the operational data products we provide freely to the public. Below are the details of where the Telegraph and the Daily Wire stories are misleading or simply wrong based on our data.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Dan Jones Physical Oceanographer, British Antarctic Survey: This article suffers from a common error in reasoning. The author focuses on individual “snapshots” of the state of the climate while ignoring the long-term trends. Those trends occur over many decades and must be observed/considered over those time scales. Andrew King Research fellow, University of Melbourne: This paper peddles common misconceptions about climate change to suggest that global warming is not a problem. It’s extremely misleading and can be easily debunked based on peer-reviewed literature. William Anderegg Associate Professor, University of Utah: This article is highly misleading and factually inaccurate. Jan Lenaerts Assistant Professor, University of Colorado, Boulder: This article mixes short-term weather phenomena and long-term climate trends, and uses logical fallacies and cherry-picked evidence to make a false claim. Alek Petty Postdoctoral associate, NASA Goddard Space Flight Center: Terrible article: Making up facts, cherry picking data, consulting non-scientists, and spouting nonsense. Daniel Swain Climate Scientist, University of California, Los Angeles: For its short length, this article contains an impressive number of falsehoods and willful misinterpretations of data. Essentially all the climate-related claims therein are either demonstrably false or “cherry picked.” Notes:[1] See the rating guidelines used for article evaluations.[2] Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from the article; comments and replies are from the reviewers. 1. There is a long-term warming trend at both the global scale and in the Arctic, which experienced its second-warmest winter on record in 2016/2017. “ever since December temperatures in the Arctic have consistently been lower than minus 20 C” Daniel Swain Climate Scientist, University of California, Los Angeles: It is indeed true that the Arctic is cold in winter—it’s hard to argue with that. But this statement belies the fact that winter 2017 was actually extraordinarily warm by historical standards, and second only to the record-shattering warmth observed just last year (in 2016). The attached plot, created by Zachary Labe and available at http://sites.uci.edu/zlabe/arctic-temperatures, shows that the -20 °C temperatures this winter are nearly 10 °C degrees above the long-term average of -30 °C! Therefore, the fact that temperatures were -20 °C this winter in the Arctic is actually a testament to just how much the Arctic has warmed in recent years. Ruth Mottram, Martin Stendel, Peter Langen, Danish Meteorological Institute (with contributions from Mads Ribergaard and Gorm Dybkjær) This statement is both wrong and misleading. Firstly, most of the Arctic has in fact been consistently warmer than -20 °C this winter. For the period 1 December 2016 to 20 April 2017, the average temperature was above -20 °C everywhere in the central Arctic except north of Greenland and the Canadian Archipelago. Over the Greenland Ice Sheet and in Eastern Siberia (and only there), the temperature was below -25 °C. Secondly, it should not be a surprise that the Arctic is very cold in winter (a period with little to no sunlight). It is much fairer to consider the difference between this winter and the average winter temperatures. Compared to our baseline of 2004-2013 everywhere in the Arctic region was at least 4 °C warmer than the average of 2004-2013 (in itself a warmer baseline period than the 1958-2002 baseline used elsewhere). Around Svalbard, it was about 4.5 °C warmer than average and in Northern Greenland, including Kap Morris Jesup, the world’s northernmost weather station (where a record +3 °C temperature was recorded on one day in February), Ellesmere Island in northeastern Canada, and large parts of eastern Siberia this winter were more than 5 °C warmer than the average as you can see below:Figure: Left, Average temperature over the Arctic for the period December 2016 to April 2017; Right, Deviation of temperature for the period December 2016 to April 2017 from the average 2004-2013.This makes the winter 2016/2017 the second warmest on record in the Arctic (after winter 2015-16), according to the European Copernicus climate service.“record temperatures brought in 2016 by an exceptionally strong El Niño” Andrew King Research fellow, University of Melbourne: Last year the annual global temperature was about 1.1 °C above a late-19th century baseline but only about 0.1°C of this was due to the El Niño—the other 1 °C is due to human influences. So while the record occurred in 2016 due to El Niño, most of the anomaly was due to climate change. “the satellites now show that in recent months global temperatures have plummeted by more that [sic] 0.6 degrees” Daniel Swain Climate Scientist, University of California, Los Angeles: El Niño events do indeed elevate global temperatures temporarily, and this is partly why global temperatures in 2016 were so extreme. But as the attached plot from NASA GISS shows, temperatures so far in 2017 have still been extraordinarily warm in a historical context, and in fact would have been record-breaking if not for the large temperature spike that occurred in 2016. In any case, it is not scientifically meaningful to measure global temperature “trends” over a two year period; the large and statistically significant long-term warming signal overwhelms short-term variations on multi-decadal timescales. William Anderegg Associate Professor, University of Utah: While true (and not necessarily in agreement with the more robust thermometer records for this period, this has no bearing on the long-term climate trend, which is driven by human emissions of greenhouse gases. It is misleading and a logical fallacy to claim this says anything about climate change, which is the long-term change in temperatures. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: While temperatures have declined modestly from the peak of the El Niño event, this is expected behavior, particularly in satellite records where El Niño is amplified. However, temperatures in January through April are quite above average to-date, and while we may not set a record temperature in 2017 compared to 2016, it will very likely be the second warmest year on record (at least on the surface). Through present there is no sign of any sort of pause or slowdown in any of the surface records or one of the two satellite records (the RSS groups latest version 4 record). The only record showing a continued pause is the one produced by the University of Alabama, Huntsville (the UAH record). The differences between these records and their causes is an area of active research, though we have strong reason to suspect that the surface record is quite accurate. “This means the global temperature trend has now shown no further warming for 19 years” Andrew King Research fellow, University of Melbourne: This is both cherry-picking of the data (starting with 1998), and not correct anyway. William Anderegg Associate Professor, University of Utah: This is blatantly false. Examine the trend here: Furthermore, a short time period of a few months in 2017 cannot say anything whatsoever about the long-term change in climate. Andreas Schmittner Associate Professor, Oregon State University: This statement is false. Global temperatures continue their long-term warming trend. 2. Warming in the Arctic is causing changes to the cryosphere: both sea ice and land ice (on Greenland) have been melting faster in recent years. “In April the extent of Arctic sea ice was back to where it was in April 13 years ago” Ed Hawkins Principal Research Fellow, National Centre for Atmospheric Science: In the NSIDC dataset, April 2017 was actually the equal of the lowest Northern Hemisphere extent on record (tied with 2016 on 13.83 M km2). Ruth Mottram, Martin Stendel, Peter Langen, Danish Meteorological Institute This statement is misleading. Arctic sea ice extent in April was significantly lower than the long-term average—but varies substantially from day to day and year to year as processes such as wind and waves and short-term weather variability have a substantial effect on sea ice extent, particularly at this time of year. However, over the long term since 1979, the April sea ice extent has declined by around 3% per decade, at other times of the year the decline is even more marked. This is an example of cherry-picking dates in order to try and state that the sea ice is recovering (it’s not). It also confuses climate variability with trends over short periods. “Furthermore, whereas in 2008 most of the ice was extremely thin, this year most has been at least two metres thick.” Daniel Swain Climate Scientist, University of California, Los Angeles: Arctic sea ice volume has actually exhibited record thinness so far during 2017—beating the previous record years of 2012/2016 by a wide margin. Another nice visualization by Zachary Labe illustrates this quite clearly: “Whereas in 2008 most of the ice was extremely thin, this year most has been at least two metres thick.” Ruth Mottram, Martin Stendel, Peter Langen, Danish Meteorological Institute This is a misleading statement, as “extremely thin” is not defined and what is also not stated is that there were also substantial areas of much thicker ice in 2008. If we look at the total ice volume, which averages these effects out, on 1st May 2017 it was about 6% lower than the ice volume for the same date in 2008 according to the operational ocean and sea ice model. Again, in addition to air and ocean temperature, ice thickness depends on winds and ocean currents and shows large variations from year to year so choosing two years arbitrarily is misleading without considering the long term trend. “The Greenland ice cap last winter increased in volume faster than at any time for years.” Jan Lenaerts Assistant Professor, University of Colorado, Boulder: This is not per se completely incorrect, but the author does not tell us the whole story. The author refers to the growing of the ice sheet volume through snowfall throughout winter. The snow accumulated on Greenland in past winter (September-April) has indeed been remarkably high: However, this does not imply that the volume of the ice sheet is increasing, because (1) the ice sheet also loses ice through discharging icebergs; it is the difference between snowfall-driven growth and solid ice discharge that determines if the ice sheet gains or loses volume, and (2) the snow that accumulated during the winter will (at least partly) melt over the summer. That’s why we analyse changes to the ice sheet volume/mass on (at least) annual time scales. Only after the summer we will know how much of the accumulated snow has (not) been melted. uring the past years, the amount of melting has been record-high, and much of snow that accumulated over the winter melted and ran off into the ocean. Concurrently, ice discharge continued, so the Greenland ice sheet LOST considerable volume. We will know in September how much the ice sheet has changed volume this year. Two additional remarks: (a) The word “faster” should not have been used here. We are not talking about the rate of speed, but rather about the total change in volume. Also, it is easier to talk about “mass changes” than “volume changes” since the former is not sensitive to the density of the medium we are talking about (snow has a lower density than ice!). (b) The enhanced snowfall, ironically, is most probably also a signal of the strongly warming Arctic: as the atmosphere warms, it contains more moisture, and generates more precipitation. Also, record-low fall and winter sea ice extent led to large streaks of open water that might have contributed to additional moisture loading of the air. Ruth Mottram, Martin Stendel, Peter Langen, Danish Meteorological Institute Here the author confuses short-term variability (i.e., weather) with a significant change to the Greenland ice sheet. Until a full annual cycle is considered, it is impossible to say if the volume is increasing or not. We can confirm that there has been a record amount of snow and rain over Greenland this winter, most of it fell in October due to extra-tropical hurricane Nicole. However this “extra” winter snowfall is not yet part of the Greenland ice sheet but a snow layer sitting on top of it and the extra gain in snow may be easily wiped out by a warm sunny summer. The summer is by far the most important time of year for the ice sheet—it determines if the ice sheet will grow or shrink so we will not know until September if this winter’s extra snow will have any effect on the overall ice sheet mass budget. Furthermore, we should bear in mind that extra snowfall in Greenland is actually predicted in most climate models, (a warmer atmosphere = more moisture = more snowfall in Greenland) as a consequence of climate change. We should also note that almost all of the additional above average snow fell in the East and South, and north-western Greenland actually has less snow than usual (which you can see in the figure above)."
https://science.feedback.org/review/global-sea-level-rise-accelerating-despite-heartland-institute-reports-claims-otherwise/,Inaccurate,"Heartland Institute, Craig Idso, Fred Singer, Robert Carter, 2024-08-14",Best available data show sea-level rise is not accelerating. Local and regional sea levels continue to exhibit typical natural variability—in some places rising and in others falling.,,"Factually Inaccurate: The observed rate of global sea level rise has increased in comparison to preceding decades or centuries.  Fails to Grasp Significance of Observation: Local sea level change can differ from the global average because of land surface elevation trends or ocean circulation variability, but these additional local factors are not indicative of the global sea level trend.","Globally, sea level is rising due to melting glacial ice and warming oceans, and the current rate of sea level rise is faster than past rates.",Best available data show sea-level rise is not accelerating. Local and regional sea levels continue to exhibit typical natural variability—in some places rising and in others falling.,,"Benjamin Horton Professor, Earth Observatory of Singapore: False. Comparison of long tide gauge records and multi-centennial to millennial scale sea-level reconstructions from the same region indicates that the rate of rise during the instrumental period (since ~1850 CE) was significantly faster than it was during the late Holocene (the 4000–2000 years prior to ~1850 CE). The data demonstrate that an acceleration in the rate of sea-level rise occurred. Kopp et al (2016) Temperature-driven global sea-level variability in the Common Era, Proceedings of the National Academy of Sciences [the article concludes: “A significant global sea level acceleration began in the 19th century and yielded a 20th century rise that is extremely likely (probability P ≥ 0.95) faster than during any of the previous 27 centuries.”] Daniel Swain Climate Scientist, University of California, Los Angeles: This statement is false. A wide range of direct measurements (i.e. tidal gauges) and indirect measurements (i.e., gravity monitoring satellites) show that the rate of sea level rise has increased (i.e., accelerated) in recent years*. Dieng et al (2017) New estimate of the current rate of sea level rise from a sea level budget approach, Geophysical Research Letters [the article concludes: “An important increase of the global mean sea-level rate is found during the second half of the altimetry era (2004–2015) compared to the 1993–2004 time span, mostly due to Greenland mass loss increase and also to slight increase of all other components of the budget.”] Peter deMenocal Professor, Lamont-Doherty Earth Observatory, Columbia University, and Director, Center for Climate and Life: This is untrue. The best available data show that the rate of sea level rise has more than doubled in just the last decade*. Hay et al (2015) Probabilistic reanalysis of twentieth-century sea-level rise, Nature Jeremy Fyke Postdoctoral researcher, Los Alamos National Laboratory: Use of “accelerating” is misleading. Even if the rate wasn’t accelerating (which it is), the fact of a steady rise would still be important. Global average sea level is unambiguously rising. Regions where sea level is falling are regions where local sea level signals are large enough to counteract the global trend—for example, in Baffin Bay and parts of Scandinavia, where continued residual land uplift is continuing, associated with the unweighting of the land from loss of last glacial maximum ice sheets. More details on why local sea level changes can differ from global change can be found in the IPCC report, chapter 13. A recent study finds that sea-level rise recently accelerated significantly, the rate between 1993 and 2012 being three times faster than the rate before 1990*. Dangendorf et al (2017) Reassessment of 20th century global mean sea level rise. Proceedings of the National Academy of Sciences"
https://science.feedback.org/review/the-sun-cannot-explain-recent-global-warming-contrary-to-what-heartland-institute-report-claims/,Incorrect,"Heartland Institute, Craig Idso, Fred Singer, Robert Carter, 2024-08-14","Solar forcings are not too small to explain twentieth century warming. In fact, their effect could be equal to or greater than the effect of CO<sub>2</sub> in the atmosphere.",,Incorrect: The fingerprints of the observed climatic changes do not match those that a change in solar irradiance would generate.  Factually Inaccurate: No estimate of 20th century climate forcings (warming or cooling influences) shows the solar forcing to be close to the effect of increased CO2. ,"The warming influence of CO2 has been much greater than that of the Sun over the past century, and the pattern of observed climate change cannot be explained by solar forcing.","Solar forcings are not too small to explain twentieth century warming. In fact, their effect could be equal to or greater than the effect of CO<sub>2</sub> in the atmosphere.",,"Timothy Osborn Professor, University of East Anglia, and Director of Research, Climatic Research Unit: There is strong evidence that solar forcing cannot explain much of the observed warming at all. The “fingerprint” of solar forcing does not match the observed changes at all, neither over time nor space. Solar forcing would warm both the stratosphere and the surface of the Earth, whereas CO2 warms the surface (and the troposphere) but cools the stratosphere. Using radiosondes and (more recently) satellites, we have observed a warming surface and troposphere together with a cooling stratosphere. See Santer et al (2013)* for one of many studies providing this evidence. Figure –Zonal-mean atmospheric temperature trends in satellite observations from January 1979 to December 2012 showing warming of the lower atmosphere (troposphere) and cooling of the upper-atmosphere (stratosphere), from Santer et al (2013)* Santer et al (2013) Human and natural influences on the changing thermal structure of the atmosphere, PNAS Britta Voss Postdoctoral Research fellow, U.S. Geological Survey: Solar forcing is much smaller than CO2 forcing. As this figure from the latest IPCC report shows, CO2 radiative forcing (1.68 W/m2) dwarfs solar forcing (0.05 W/m2). Along with other greenhouse gases, CO2 dominates the total radiative forcing when all positive and negative factors are taken into account. Figure – Radiative forcing estimates in 2011 relative to 1750. Values are global average radiative forcing, partitioned according to the emitted compounds or processes that result in a combination of drivers. Source IPCC AR5 Peter deMenocal Professor, Lamont-Doherty Earth Observatory, Columbia University, and Director, Center for Climate and Life: This is untrue. Solar forcing in the visible spectrum is far too small to explain recent warming. Furthermore solar variability would suggest a cooling trend more recently whereas the Earth is clearly warmed."
https://science.feedback.org/review/climate-sensitivity-estimate-given-in-heartland-institutes-report-is-misleading/,Misleading,"Heartland Institute, Craig Idso, Fred Singer, Robert Carter, 2024-08-14","Doubling the concentration of atmospheric CO2 from its pre-industrial level, in the absence of other forcings and feedbacks, would likely cause a warming of ~0.3°C to 1.1°C",,"Misleading: The claim only highlights warming in the absence of any feedbacks, meaning it has limited relevance to the real behavior of the climate system. Even taken on its own, the CO2-only warming range given in this claim is lower than can be determined from physics.","Without additional feedbacks, a doubling of CO2 would cause 1.2 - 1.3°C warming. Feedbacks do exist in the real world, however, and this increases the expected warming to 1.5 - 4.5°C.","Doubling the concentration of atmospheric CO2 from its pre-industrial level, in the absence of other forcings and feedbacks, would likely cause a warming of ~0.3°C to 1.1°C, almost 50 percent of which must already have occurred.",,"Jeremy Fyke Postdoctoral researcher, Los Alamos National Laboratory: Neglecting feedbacks in this statement is seriously misleading to uninformed readers. Feedbacks have been clearly identified as major amplifiers of the initial CO2-forced change. These feedbacks are explicitly resolved in climate models. Mark Zelinka Research Scientist, Lawrence Livermore National Laboratory: The first part of the statement is true, though the numerical values are off. Without other feedbacks to amplify the planetary heating due to CO2, the expected global warming from doubling CO2 is about 1.2 to 1.3°C. See p.96 of Roe (2008)1for a nice explanation of this. Of course, we know that there are important feedbacks in the climate system, and several of them are strong and positive, causing additional warming on top of this basic response. Narrowing down the plausible ranges of the strength of these feedbacks is an abiding goal of climate science (e.g. Stevens et al, 2016)2. Evidence has consistently pointed towards a global warming of 3°C for a doubling of CO2, albeit with uncertainty. See Armour (2017)3 for a recent study that adds to this body of evidence. So the quoted no-feedback warming of ~1 degree is completely irrelevant to Earth. It is useful only in an academic sense as a hypothetical baseline climate response that is subsequently modified by feedbacks. The second part of the statement—that half of the warming must have already occurred (presumably because CO2 levels have increased by 50% since preindustrial)—is not true. We do not expect the ultimate global warming due to doubling of CO2 to occur at the exact moment that CO2 is doubled any more than we expect water to instantaneously boil when a pot is placed on a hot stove. There is a lag between the heating due to CO2 and the surface temperature response owing to the heat capacity of the climate system, especially the ability of the ocean to take up heat. 1- Roe (2008) Feedbacks, Timescales, and Seeing Red, Annual Reviews 2- Stevens et al (2016) Prospects for narrowing bounds on Earth’s equilibrium climate sensitivity, Earth’s Future 3- Armour (2017) Energy budget constraints on climate sensitivity in light of inconstant climate feedbacks, Nature Climate Change James Renwick Professor, Victoria University of Wellington: The CO2-only warming is at the top end of this range. The water vapor feedback roughly doubles the warming, and other feedbacks (such as ice-albedo) add another degree or so. The most likely value for real-world climate sensitivity is around 3°C, with a range from about 1.5°C to 4.5°C, as has been well known for 40 years."
https://science.feedback.org/review/cnn-interview-william-happer-incorrectly-claims-temperatures-dont-match-climate-model-projections/,Incorrect,"CNN, William Happer, 2017-04-22","The temperature is not rising nearly as fast as the alarmist computer models predicted. You know, it’s much, much less, factors of 2 or 3 less.",,"Unsupported: Observed warming since the 1970s is consistent with climate model projections, the factor of 2 or 3 mentioned by Happer is not supported by available observations.  Fails to grasp significance of observation: Comparing short-term natural variations in global temperature with average long-term trends from model simulations is not an apples-to-apples comparison.","Global surface temperatures are increasing consistent with the long-term trend projected by climate models, which are useful tools for understanding the consequences of continued greenhouse gas emissions.","The temperature is not rising nearly as fast as the alarmist computer models predicted. You know, it’s much, much less, factors of 2 or 3 less. So the whole basis for the alarmism is not true, it’s based on flawed computer modeling.",,"Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: Dr. Happer’s assertion that models show 2x to 3x greater warming than observations is incorrect. At the surface (where we all live) models predict a rate of warming of 0.2°C per decade since 1970, while NASA observes warming of around 0.18°C during the same period. During this period models have been running about 10% too hot, hardly 200% to 300%. Similarly, the observations from all the different groups that measure global surface temperatures are well within the envelope of model projections: Over a longer timeframe, since we first started observing global temperatures in the late 1800s, models have also matched observations fairly well: Cowtan et al (2015) Robust comparison of climate models with observations using blended land air and ocean sea surface temperatures, Geophysical Research Letters Mat Collins Professor, University of Exeter: Looking over the last 50 years, for example, the models and the observations are consistent in terms of the rates of global temperature warming that we expect from human activities. Over shorter decadal periods, there are natural fluctuations in climate in the real world that are much harder to predict. It is true that models do not provide perfect simulations of the real world climate. However, we have considerable confidence in long-term trends at the global scale. For shorter time scales and for regional scales, we still have some work to do. Pierre Friedlingstein Professor, University of Exeter: Climate models are doing an excellent job reproducing the warming of the 20th century. They simulate a warming consistent with the observations and they can actually attribute the warming trend over the century to the observed increase in CO2, other greenhouse gases, and aerosols. What they have a harder time simulating in phase with observations is the natural variability—in particular the relative pause in warming that occurred in the last decade (1998-2013 or so). But again, this has very little to do with CO2 and climate change; this is mainly about decadal variability in the global ocean circulation. "
https://science.feedback.org/review/cnn-interview-william-happer-misleads-impact-rising-carbon-dioxide-plant-life/,Misleading,"CNN, William Happer, 2017-04-22","there's this myth that's developed around carbon dioxide that it's a pollutant […] Carbon dioxide is a perfectly natural gas, it’s just like water vapor, it’s something that plants love.",,"Misrepresents a complex reality: While ecosystems on land have taken up CO2 emitted by humans, this is not simply a beneficial interaction. Plants require more than just CO2, and the climatic effects of greenhouse gas emissions can have negative impacts on ecosystems, as well.","Land ecosystems absorb a portion of human-caused CO2 emissions, which has indeed increased plant growth. But CO2 also negatively impacts on plants and ecosystems as well as human societies by causing the climate to change significantly.","there's this myth that's developed around carbon dioxide that it's a pollutant […] Carbon dioxide is a perfectly natural gas, it’s just like water vapor, it’s something that plants love. They grow better with more carbon dioxide, and you can see the greening of the Earth already from the additional carbon dioxide in the atmosphere.",,"Sara Vicca Postdoctoral research fellow, University of Antwerp: That claim is correct, and it is generally assumed the elevated CO2 concentrations have contributed considerably to the land carbon sink (ca. 30% of our CO2 emissions have been absorbed by land ecosystems). The claim may still be misleading, though. Plants don’t only need CO2 and water, but also nutrients like nitrogen and phosphorus. If the latter are not sufficiently available, plants may not respond to elevated CO2 at all. Moreover, climatic changes (and particularly extreme events) are an important threat to ecosystems and to the land carbon sink. It is expected that nutrient limitations and extreme events will reduce the land carbon sink and may eventually turn the land into a source of CO2. I didn’t mention soil (for simplicity), but that’s an important part of the land carbon sink, too. Zhu et al (2016) Greening of the Earth and its drivers, Nature Climate Change Terrer et al (2016) Mycorrhizal association as a primary control of the CO2 fertilization effect, Science De Graaff et al (2006) Interactions between plant growth and soil nutrient cycling under elevated CO2: a meta-analysis, Global Change Biology Zaehle et al (2015) Nitrogen Availability Reduces CMIP5 Projections of Twenty-First-Century Land Carbon Uptake, Journal of Climate Zhang et al (2014) Nitrogen and phosphorous limitations significantly reduce future allowable CO2 emissions, Geophysical Research Letters Reichstein et al (2013) Climate extremes and the carbon cycle, Nature Alexis Berg Research Associate, Harvard University: Yes, we are seeing an increase in vegetation around the world, with satellites showing up to 50% of the land surface greening over the last 30 years, most of it being indeed attributed to increased atmospheric CO2*. This is not a surprise. This vegetation increase is consistent with the fact that we know that about a quarter of our CO2 emissions is being taken up by the land biosphere (another quarter going into the oceans, and the remainder staying in the atmosphere). This greening is taken into account in climate models. The real question is how long this greening is going to go on (there are already indications that it is slowing down), as we expect that as climate warms further, adverse impacts on ecosystems may start to offset the positive impact of increased atmospheric CO2—particularly in places where regional climate is moving away from the “comfort zone” of current ecosystems. Zhu et al (2016) Greening of the Earth and its drivers, Nature Climate Change Jean-François Exbrayat Post-doctoral Research Fellow, The University of Edinburgh: Carbon dioxide is a gas that is naturally present in the atmosphere. Plants grow by taking up CO2 from the atmosphere through the process of photosynthesis. Terrestrial ecosystems have taken up about 20-30% of fossil-fuel emissions since the 1960s[1]. Through this so-called “CO2-fertilization”, plants help reduce the growth of atmospheric CO2 responsible for climate change, and this might be what William Happer refers to when talking about greening. A global “greening”, (i.e., longer growing seasons) of the Earth has also been detected in satellite observations of leaf area index from the 1980s to the present day, and modelling experiments have attributed 70% of this greening to CO2 fertilization[2]. However, plants grow better with more CO2 only if they also have access to nutrients like nitrogen and phosphorus to fix the photosynthesised carbon. For example, results from Free-Air CO2 Enrichment (FACE) experiments[3] have shown that the initial enhancement of plant productivity under CO2-fertilization was declining through time. This enhancement could, however, be restored and maintained through an additional nitrogen treatment. Results from another FACE experiment in Australia[4] have recently shown that, under current phosphorus limitations, no additional growth was recorded under increased CO2. These results from FACE experiments raise uncertainty on the sustainability of the CO2-fertilization effect in mostly nitrogen-limited temperate and boreal forests and mostly phosphorus-limited tropical ecosystems. Accordingly, adding nitrogen and phosphorus limitations on plant growth in Earth system models reduces the projected capacity of the land surface to continue offsetting fossil-fuel emissions during the 21st century[5]. [1] Le Quéré et al (2016) Global Carbon Budget 2016, Earth System Science Data [2] Zhu et al (2016) Greening of the Earth and its drivers, Nature Climate Change [3] Norby et al (2010) CO2 enhancement of forest productivity constrained by limited nitrogen availability, PNAS [4] Ellsworth et al (2017) Elevated CO2 does not increase eucalypt forest productivity on a low-phosphorus soil, Nature Climate Change [5] Wieder et al (2015) Future productivity and carbon storage limited by terrestrial nutrient availability, Nature Geoscience Pierre Friedlingstein Professor, University of Exeter: This is the usual misleading argument that if CO2 is good for plants, it cannot be bad for the climate. Happer’s statement is correct—CO2 is needed for plant growth (along with water, nutrients, and energy from the sun)—but it does not change the fact that CO2 is a greenhouse gas. It increases the radiative forcing of the planet and leads to warming, as observed over the last century. What he says is like saying, “Sun cannot cause skin cancer. The sun is natural, it’s something plants love, they grow better with more sunshine!”"
https://science.feedback.org/review/bloomberg-accurately-describes-rapidly-changing-arctic-eric-roston-blacki-migliozzi/,2,"Bloomberg, by Blacki Migliozzi, Eric Roston, on 2017-04-19.",,"""How a Melting Arctic Changes Everything""",,,,,"This Bloomberg article gives a brief overview of ways in which the Arctic is changing as it warms, including the loss of sea ice and the thawing of permafrost. Scientists who reviewed the article found that it accurately described these changes, and illustrated them using appropriate datasets. However, several confident statements could be qualified with additional context to provide a clearer picture.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Michel Tsamados Lecturer (Assistant Professor), University College London: The quality of the figures along with the accuracy of the text make this a very good summary of the current state of the cryosphere in the Arctic region. Jennifer Francis Senior Scientist, Woods Hole Research Center: Changes in the Arctic are breath-taking and extremely worrisome. This article does an excellent job of summarizing some of the most conspicuous ones in language understandable by public audiences.Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from the article; comments and replies are from the reviewers. Declining Arctic sea ice cover and thawing permafrost are both complex feedbacks that amplify global warming: The loss of reflective sea ice means more sunlight absorbed by the dark Arctic Ocean, while thawing permafrost can release greenhouse gases to the atmosphere. “Scientists refer to these dramatic physical changes as ‘Arctic amplification,’ or positive feedback loops. It’s a little bit like compound interest. A small change snowballs, and Arctic conditions become much less Arctic, much more quickly.” Michel Tsamados Lecturer (Assistant Professor), University College London: Along with positive feedbacks (albedo, ice weakening, etc.) come negative feedbacks (faster growth of thinner ice, compaction, etc.) which make the fragile thin sea ice cover surprisingly resilient. So while the extent and area of sea ice might be at a lowest point, it remains to be seen if this will materialize in a similar level for the volume of ice. Having said that, the temperature and ice coverage anomalies of the 2016/2017 Fall/Winter have been remarkable and have further triggered scientists’ curiosity. “Sea ice has diminished much faster than scientists and climate models anticipated.” François Massonnet Postdoctoral Research Fellow, Université catholique de Louvain: Caution must be exercised when making such statements, and in particular how they should be interpreted. It is a fact that the observed linear trend in summer Arctic sea ice extent is more negative than the average of all the models having participated to the third and fifth phase of the Coupled Model Inter-comparison Project (CMIP3/5). It is also a fact that individual model realizations, and in fact a non-negligible number of them, have more negative trends than observed: this is the case for 17 out of 66 (~26%) in the CMIP5 ensemble (figure below). From there, we can’t robustly exclude that the observed and simulated trends are statistically different from each other. Figure – (a) Time series of sea ice extent for the Arctic in September, as modelled in CMIP5 (coloredlines) and observations-based (NASA and NSIDC). Each model is represented with a single simulation. (c) CMIP5 sea ice extent trend distributions over the period 1979–2010 for the Arctic in September. Altogether 66 realizations are shown from 26 different models (historical simulations extended after 2005 with RCP4.5 projections). They are compared against the observations-based estimates of the trends (green and blue vertical lines).Source: adapted from IPCC AR5 WG1, Chapter 9, Fig. 9.24 Let’s make a thought experiment and rewind nature back to 1979. Then let’s clap our hands, creating an infinitesimal disturbance in the atmosphere. Due to the chaotic nature of the atmosphere, this disturbance will cause nature to follow a different path from the one we have known. The trend in sea ice extent will also be different, and potentially very different from the one we have observed, according to model simulations*. What to understand from this? While these random effects of internal variability can be averaged out by running multiple times the same models, or different models, the same can’t be done for the (one) observation we have. We have to acknowledge that the difference between the (one) observed trend and the average simulated trend can, in part, be explained by internal variability that, by definition, historical climate model simulations are not supposed to anticipate. Hence, the statement that sea ice extent has shrunk faster than anticipated has to be taken with care. Notz (2015) How well must climate models agree with observations?, Philosophical Transactions of the Royal Society A Jennifer Francis Senior Scientist, Woods Hole Research Center: The main take-home message is that sea ice is disappearing very fast and we know why. It’s a clear response to the fact that carbon dioxide concentrations in the atmosphere are now higher than have been in at least 2 million years, mainly due to burning fossil fuels. The sea ice is a critical component of the Earth’s climate system, and losing over half of it in less than a human generation is already having repercussions well beyond the Arctic. “Arctic land stores about twice as much carbon as the atmosphere. While growing seasons—which are now either longer or newly possible, depending on the exact location—suck in carbon dioxide during the spring and summer, scientists believe the thawing lands are now emitting more carbon than they take in.” Jeff Chanton Professor, Florida State University: Yes, and in addition they will increase the methane that they emit, which may offset carbon that might be taken up if that is the case. “Perhaps the most visually dramatic change in the landscape has been occurring in Russia. Warming temperatures have accelerated the rate of natural underground methane leaks. The gas builds up in the soil, forming mounds called ‘pingoes.’ When the pressure becomes too great, the ground explodes, leaving 30 to 40-meter-wide craters.” [picture] Carolyn Ruppel Research Geophysicist, United States Geological Survey: In the review paper* that we published early this year, we said only this: “In recent years the discovery of deep, rapidly developed Yamal Peninsula craters that emit CH4[methane] has been attributed by some to thawing gas hydrates, although recent analyses of high-resolution satellite imagery implies pingo collapse as a more likely cause”. Normal pingoes are widespread even on the Alaskan North Slope, and they are generally believed to be ice-cored. The “alternative” pingoes that have been in the news recently and that the Bloomberg article alludes to would not have ice at their cores, according to that interpretation. Many workers have measured high methane concentrations in and near these craters on the Yamal Peninsula, but I have no way of knowing whether (a) methane is genetically related to the craters’ evolution or (b) the craters evolve first by still-not-understood processes and the crater then has access to methane that is already in the surrounding/underlying soils or produced by microbes acting on buried organic carbon (so the methane leaking into the crater is what causes high concentrations within). I also can’t say whether the phenomenon of crater formation is widespread enough and whether these craters are releasing enough methane to the atmosphere for these features to have an appreciable impact on high-latitude methane releases. Ruppel and Kessler (2017) The interaction of climate change and methane hydrates, Reviews of Geophysics"
https://science.feedback.org/review/climate-context-for-a-wet-winter-in-drought-stricken-california-in-the-la-times-rong-gong-lin-ii-paige-st-john-los-angeles-times/,0.8,"Los Angeles Times, by Paige St. John, Rong-Gong Lin II, on 2017-04-12.",,"""From extreme drought to record rain: Why California's drought-to-deluge cycle is getting worse""",,,,,"This article in The Los Angeles Times discusses the recent exceptionally wet winter in California, which followed several years of extreme drought conditions. These events are put into the context of trends in recent decades and the future projections of continued human-caused climate change. Warming temperatures are expected to increase the magnitude of both dry years (since evaporation increases with temperature) and wet years (since a warmer atmosphere has a greater “water-holding capacity”), which can sound counterintuitive at first. Scientists who reviewed the article found it to be a generally accurate description of the state of scientific knowledge on these complex topics.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Daniel Swain Climate Scientist, University of California, Los Angeles: This timely article accurately characterizes the broader climate context of California’s rapid transition from drought to flood. Andreas Prein Project Scientist, National Center for Atmospheric Research: The article is accurate and highlights the challenges that California’s water resource managers are facing due to climate change. There are some issues with differentiating natural climate variability and forced climate change but the main points are correct. Baird Langenbrunner Associate Editor, Nature Climate Change: This article is balanced and accessibly written, and its description of the recent history of California’s weather is accurate and clear. The authors do not substantiate all of their claims, nor do they explain mechanisms underlying the changes they discuss, but for its intended purpose—an article contextualizing recent California extremes within the historical record and how they might be changing—it seems to fit the bill. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from the article; comments and replies are from the reviewers. Extremes of drought and precipitation in California have increased in frequency, which is also a pattern climate models predict for the future. Natural year-to-year variability of California precipitation is high though, so it is uncertain whether the influence of climate change is already detectable. “The extreme cycles of dry and wet weather appear to have been intensifying over the last three decades.” Daniel Swain Climate Scientist, University of California, Los Angeles: There is indeed observational evidence that California precipitation extremes—and the atmospheric phenomena that cause them—have occurred more frequently in recent years*, although that signal has only recently emerged from the “noise” of natural climate variability. There is also an expectation that such swings between extreme dry and extreme wet will continue to become more pronounced as the climate warms*. Swain et al (2016) Trends in atmospheric patterns conducive to seasonal precipitation and temperature extremes in California, Science Advances Diffenbaugh et al (2015) Anthropogenic warming has increased drought risk in California, PNAS Wang et al (2015) The North American winter ‘dipole’ and extremes activity: a CMIP5 assessment, Atmospheric Science Letters Yoon et al (2015) Increasing water cycle extremes in California and in relation to ENSO cycle under global warming, Nature Communications Berg and Hall (2015) Increased Interannual Precipitation Extremes over California under Climate Change, Journal of Climate Gao et al (2017) Twenty-First-Century Changes in U.S. Regional Heavy Precipitation Frequency Based on Resolved Atmospheric Patterns, Journal of Climate A. Park Williams, Assistant Research Professor, Lamont-Doherty Earth Observatory: Yes, variability in California precipitation appears to have been higher in the past 3-4 decades than the previous decades, but it is not (and cannot be) clear that that the variability in precipitation is actually currently in the act of increasing. I say that it cannot be clear because it takes decades of data (say 2-3) to characterize the current “variability” of the climate. Based on my calculations, variability in annual precipitation totals increased considerably during the second half of the 1900s and then has remained at this relatively high level for the past couple decades, but has not clearly continued to increase. This latest swing from record dry to very wet in the last year is consistent with high variability, but it’s a single event and not necessarily indicative of a trend. There are some logical links, however, that support the inference that wild swings like the current one should be expected to become more likely. First, droughts are becoming increasingly impacted by warming temperatures. Even if precipitation behavior didn’t change at all, years with low precipitation would correspond to less and less water availability for humans and ecosystems. Second, current climate models project variability of California precipitation to increase in the future, with an increase in the frequency of years with very high precipitation totals becoming detectable sometime in the first half of this century, and an increase in the frequency of years with very low precipitation totals becoming detectable in the second half of this century*. It should always be remembered, however, that models have a tough time with California precipitation. California is right on the boundary between projections of drying to the south and wetting to the north. I personally believe the basic expectation that California precipitation should become more variable, but beyond that I don’t yet put much stock in what models have to say about the future of precipitation in California. So, variability has increased overall in the last century, and this is consistent with what models project to occur as a result of greenhouse-gas driven climate change. The increase in variability hasn’t been a monotonic trend, however, and it is not obvious from the data that the trend is continuing now as rapidly as it was in previous decades. This suggests that other low-frequency processes are also at play that influence decade-to-decade changes in the variability and magnitude of annual precipitation totals, making it particularly difficult to determine the degree to which this current event can be attributed to climate change. Nonetheless, California would be wise to prepare for more events like these. Berg and Hall (2015) Increased Interannual Precipitation Extremes over California under Climate Change, Journal of Climate “Warm weather worsened the most recent five-year drought, which included the driest four-year period on record in terms of statewide precipitation. California’s first-, second- and third-hottest years on record, in terms of statewide average temperatures, were 2014, 2015 and 2016.” Daniel Swain Climate Scientist, University of California, Los Angeles: This claim is supported by a wide range of scientific research*. Record warmth during the recent drought has also been directly implicated in some of the most iconic drought impacts, such as extreme lack of Sierra Nevada snowpack* and a large increase in wildfire intensity*. Diffenbaugh et al (2015) Anthropogenic warming has increased drought risk in California, PNAS Williams et al (2015) Contribution of anthropogenic warming to California drought during 2012–2014, Geophysical Research Letters Belmecheri et al (2016) Multi-century evaluation of Sierra Nevada snowpack, Nature Climate Change Yoon et al (2015) Increasing water cycle extremes in California and in relation to ENSO cycle under global warming, Nature Communications Baird Langenbrunner Associate Editor, Nature Climate Change: There is evidence that warmer temperatures across the globe affect large-scale atmospheric dynamics, which in turn feed into regional weather patterns. The relevant example here is the argument that a warming Arctic will reduce large-scale temperature gradients in the atmosphere, which will in turn affect (and be affected by) the complex path that storms follow across the Pacific Ocean as they approach the North American west coast. While the extent to which this has already happened is debatable*, there is agreement that it will be a robust signal if Arctic warming continues unabated*. Cohen et al (2014) Recent Arctic amplification and extreme mid-latitude weather, Nature Geoscience Overland et al (2015) Nonlinear response of mid-latitude weather to the changing Arctic, Nature Climate Change Screen (2017) Climate science: Far-flung effects of Arctic warming, Nature Geoscience “And this winter’s near disaster at the overflowing Lake Oroville was in part caused by warm storms too.” Daniel Swain Climate Scientist, University of California, Los Angeles: The skewed rain-snow ratio this season certainly contributed to some of the precipitation-related impacts this winter. While winter 2016-2017 was not exceptionally warm in the Sierra Nevada, especially relative to recent record-warm years, it was still warmer than average. In middle elevation zones of the Sierra Nevada, precipitation fell as rain rather than snow more often that would have historically been the case—leading to a snowpack that significantly lagged overall liquid precipitation (although both were well above average). (See this article in Eos.) “Not everyone is convinced that the evidence is in that climate change is responsible for extreme swings between drought and deluge.” Daniel Swain Climate Scientist, University of California, Los Angeles: There is a considerable and growing body of scientific evidence (see above references) demonstrating that California will likely experience increasingly large swings between extreme wet and extreme dry conditions. The evidence that climate change has already caused such an increase is somewhat less strong—mainly because there are relatively few extreme events in the historical record from which to draw such conclusions. Therefore, this statement is imprecise, and may be misleading if it is intended to convey that scientists substantially disagree regarding the likely future increase in California precipitation extremes. Whether such an increase is yet detectable in the historical record is indeed uncertain; there is much greater certainty regarding the likely direction of future change. “‘The dry periods are drier and the wet periods are wetter,’ said Jeffrey Mount, a water expert and senior fellow at the Public Policy Institute of California.” Andreas Prein Project Scientist, National Center for Atmospheric Research: This is seen in assessments of atmospheric reanalyses, which show a decreasing frequency of rain-producing weather systems over California but higher rain rates over the last 35 years*. Prein et al (2016) Running dry: The U.S. Southwest’s drift into a drier climate state, Geophysical Research Letters"
https://science.feedback.org/review/sea-level-rise-already-practical-concern-miami-bbc-story-accurately-explores-amanda-ruggeri-bbc/,1.7,"BBC, by Amanda Ruggeri, on 2017-04-04.",,“Miami’s fight against rising seas”,,,,,"This BBC feature article discusses the challenges that sea level rise poses for Miami, Florida in detail. Global sea level rise projected to occur in the coming decades due to human-induced climate change threatens coastal infrastructure in low-lying areas like southeast Florida. Scientists who reviewed this story found it to be insightful and generally accurate. They note that care should be taken not to misinterpret short-term variations in local sea level rise trends, such as the higher rate of sea level rise in Florida over the past decade, which is not expected to continue over the long term.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Tal Ezer Professor, Old Dominion University: The information in this story is generally correct—the frequency and severity of flooding is accelerating due to sea level rise, and the quoted scientists from NOAA and FAU are credible experts in this field. Andrea Dutton Visiting Associate Professor, University of Wisconsin: The article provides many internal references to peer-reviewed research, which supports many of the scientific claims made here, including the observation that in recent years the rate of sea-level rise in southeast Florida has accelerated. Additional insight on the implications of the research is made, including the observation that vulnerable infrastructure situated at lower elevations will be critical to sustain even those structures that are at slightly higher elevation; hence it is not the elevation of your home that is as critical as the elevation of the infrastructure that supports it. However, having argued throughout the piece that sea levels are rising quickly in this region and that a swift, coordinated response is required, I found the ending overly optimistic. It is not helpful to sustain the unrealistic belief that human innovation will enable us to just engineer our way out of this situation in south Florida indefinitely.Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from the article; comments and replies are from the reviewers. 1.The 21st Century could see a meter or more of sea level rise as the oceans continue to warm and glacial ice is lost, presenting a threat to low-lying coastal areas like southeast Florida. “Not only are sea levels rising, but the pace seems to be accelerating” Benjamin Horton Professor, Earth Observatory of Singapore: The largest change in rate of sea-level rise is between the background pre-industrial period and the 20th century. Sea-level rose 1.27 ± 0.09m in northeastern Florida (USA) during the past ~2600 years, a rate of about 0.49 mm/yr. The tide-gauge data from nearby Fernandina Beach, measures 1.91 ± 0.26mm/yr of RSL rise since 1900CE. “The most frequently-used range of estimates puts the likely range between 15-25cm (6-10in) above 1992 levels by 2030, and 79-155cm (31-61in) by 2100.” Andrea Dutton Visiting Associate Professor, University of Wisconsin: It is true that these are commonly used projections in this region. This statement refers to the Unified Sea Level Rise Projection that was produced by the Southeast Florida Regional Compact on Climate Change. “enough credible projections have been done to put together a range of scenarios that researchers are confident about” Andrea Dutton Visiting Associate Professor, University of Wisconsin: Many projections have been done, but they may very well underestimate the true expected range of scenarios. “But as more data comes in, even the worst-case estimates may turn out to be too low: for example, researchers recently discovered that ice is melting more rapidly than expected from both Antarctica and Greenland, plus gained a better understanding of how melting ice sheets actually affect sea-level rise. ‘The unlikely scenarios are now, all of a sudden, becoming more probable than they once were thought to be,’ says Sweet.” Andrea Dutton Visiting Associate Professor, University of Wisconsin: This is true, based on the research cited here. The dynamics of rapid ice sheet retreat remain uncertain which introduces uncertainty into the projections. “The most dramatic impacts may not be felt for 50 or 100 years.” Andrea Dutton Visiting Associate Professor, University of Wisconsin: While the most dramatic effects may not be felt until 50 to 100 years from now, that does not mean that dramatic impacts will not occur before then. “many of south Florida’s drainage systems and seawalls are no longer enough” Andrea Dutton Visiting Associate Professor, University of Wisconsin: This statement is true based on several different analyses. For example, in a study* that quantified the reduction of flood control capabilities of coastal water control gravity structures owing to increased sea level rise, they found that “sea level change could negatively impact nearly half the coastal flow control structures in the coming decades, unless adaptive measures are implemented to mitigate such impacts.” Obeysekera et al (2011) Climate change and its implications for water resources management in south Florida, Stochastic Environmental Research and Risk Assessment 2.Over shorter timescales, regional sea level trends can differ significantly from the long-term trend due to additional factors like ocean circulation. “Sea level rise is global. But due to a variety of factors – including, for this part of the Atlantic coast, a likely weakening of the Gulf Stream, itself potentially a result of the melting of Greenland’s ice caps – south Floridians are feeling the effects more than many others. While there has been a mean rise of a little more than 3mm per year worldwide since the 1990s, in the last decade, the NOAA Virginia Key tide gauge just south of Miami Beach has measured a 9mm rise annually.” Tal Ezer,Professor, Old Dominion University:: The main reason for higher than normal local sea level rise in places like Miami, FL, and Norfolk, VA, is that in addition to well documented global sea level rise, there are places with local land subsidence and also influence from ocean currents like the Gulf Stream. The influence of the Gulf Stream on the coast is my expertise*, but the issue is quite complicated. It is true that slowdown of the Gulf Stream will cause sea level to rise along the US East Coast and there are some signs that the Gulf Stream started to slow down due to long-term climate change, weakening the entire Atlantic Ocean circulation. However, short term fluctuations in the Gulf Stream (which may or may not relate to climate change) can also create periods of higher than normal water levels and unpredictable tidal flooding, and this is an area of active recent research. Ezer et al (2013) Gulf Stream’s induced sea level rise and variability along the U.S. mid-Atlantic coast, Journal of Geophysical Research-Oceans Stefan Rahmstorf Professor, Potsdam University: This statement touches upon several issues that are indeed discussed in the scientific literature and it is essentially correct. Let’s try and disentangle things. It is correct that Virginia Key as well as other locations on the US Atlantic coast have experienced a surge of rapid sea-level rise during the past ten years or so. However, this is a very short period in terms of sea-level variations. The longer-term rise in this region (when corrected for local land subsidence) is actually in line with the global average sea-level rise, both for the past hundred years (~1.8mm per year) or measured since the early 1990s (~3 mm per year). The recent rapid rise is thus likely a short-term natural variation (a possibility mentioned later in the article) and may well be followed by a period of very little rise. In the longer run I would expect that sea-level near Miami would continue to increase roughly in line with the global mean sea-level rise, as is indeed discussed later in the article where the future projections with their uncertainties are covered well. It is correct that local sea-level rise can differ from global sea-level rise due to “a variety of factors”, including a weakening of the Gulf Stream. For the relevant period of rapid rise, the last ten years or so, such a weakening has been documented, e.g. in the direct measurements in the RAPID section at 26 °N. So the rapid sea-level rise and the weakening of the larger Gulf Stream System coincide, and have indeed been linked.* Like with sea level, over the short time scale of the past decade this is likely to be dominated by natural variability, although there are also indications of a longer-term, probably human-caused, downward trend. Greenland melting has not caused this, but likely contributed to it. To what extent the Gulf Stream weakening explains the recent rapid sea-level rise in Miami, and to what extent other factors—like changes in the predominant winds—are responsible remains an open research question. Ezer et al (2013) Gulf Stream’s induced sea level rise and variability along the U.S. mid-Atlantic coast, Journal of Geophysical Research-Oceans Benjamin Horton Professor, Earth Observatory of Singapore: True: Sea-level rise in Florida is the result of a variety of factors. But the influence of a weakening Gulf Stream will be felt more in the northeast of the US than Florida. Furthermore, land level subsidence due to glacial isostatic adjustment is less in Florida than the mid and northeast Atlantic. With respect to melting from Greenland, yes, Florida will feel a greater impact than regions to the North. But the rate of rise will be less than the global average. Focusing on the last decade and one tide gauge could be considered cherry-picking the data. Long-term (>60yrs) tide gauges should be used. Virginia Key has only been operational since 1994. Key West Tide gauge has been operational since 1901 and records a rate of sea-level rise of 2.37 mm/yr. Andrea Dutton Visiting Associate Professor, University of Wisconsin: The hypothesis that (a) the Gulf stream has weakened over this time interval and (b) that it is the primary driver of sea level rise acceleration seen farther north along the U.S. Atlantic coast is still debated (see for example, Kopp 2013)*. Kopp (2013) Does the mid-Atlantic United States sea level acceleration hot spot reflect ocean dynamic variability?, Geophysical Research Letters “Can we definitely say it’s the ocean warming?” says Sweet, who has authored several sea-level rise studies. “No. But is it indicative of what we’d expect to see? Yes.” Andrea Dutton Visiting Associate Professor, University of Wisconsin: It is not yet clear what is causing the recent uptick in the rate of sea level rise in this region over the past several years, which is not similarly recorded at tide gauges north of Cape Hatteras according to the NOAA tide gauge data. If, however, this quote refers to the long-term trend of sea-level rise in this region, then it is correct and consistent with the analysis of the latest IPCC report* (Church and Clark, (2013) Chapter 13, IPCC AR5). Church et al (2013) Chapter 13: Sea Level Change, In: Climate Change 2013: The Physical Science Basis, IPCC"
https://science.feedback.org/review/one-of-the-most-troubling-ideas-about-climate-change-just-found-new-evidence-in-its-favor-chris-mooney-washington-post/,1.25,"The Washington Post, by Chris Mooney, on 2017-03-27.",,"""One the most troubling ideas about climate change just found new evidence in its favor""",,,,,"This article in The Washington Post discusses a new study related to the hypothesis that global warming is influencing extreme weather events in the midlatitudes by changing the behavior of the jet stream. While many previous studies have explored statistical correlations, the new study provides a specific process that can plausibly explain how enhanced Arctic warming trends may trigger remote weather impacts. Specifically, it focuses on slow-moving meanders in the jet stream in the spring and summer than can cause extended periods of hot or wet weather. The scientists who reviewed the article confirm that it is accurate and insightful, and acknowledges the areas where legitimate scientific uncertainty remains.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. James Screen Associate Professor, University of Exeter: The author does a pretty good job of summarising the state of the science on this topic and the main advance made by the new Mann et al study. It conveys some of the uncertainty and difficulties in attributing changes in the jet strea—and in “stuck” weather patterns—to man-made climate change. It is worth noting that the Mann et al study only claims a climate change effect on the jet stream in summer. However, much of the research referred to in the article is about winter and invokes different physical processes to explain the possible climate change effects on the jet stream. My ranking of “high” rather than “very high” reflects the failure of this piece to fully capture the seasonal nuances of possible connections between climate change and the jet stream. Jennifer Francis Senior Scientist, Woods Hole Research Center: The new study addresses a very complicated topic in dynamic meteorology and climate science, and this article does an excellent job of explaining the main idea and its implications. It is balanced, accurate, and well written. Jim Kossin Research Scientist, NOAA's Center for Weather and Climate: Excellent article that should be very informative for a broad audience. There are a few somewhat misleading statements that place too much emphasis on the ongoing debate about how winter storms may be linked to Arctic warming, which are not directly addressed in the new paper by Mann et al. The new results might be inferred indirectly to favor one side of the debate, but this may prove to be incorrect later. Daniel Swain Climate Scientist, University of California, Los Angeles: Overall, this piece accurately describes the findings of a new research paper by Mann et al on linkages between rapid Arctic warming and extreme weather at Earth’s more temperate latitudes. While there are a couple of statements that are overly confident given available evidence in the peer-reviewed literature, the author generally does an excellent job placing this new work into the broader context of related studies over the past decade. Christopher Colose Research Scientist, SciSpace LLC, NASA Goddard Institute for Space Studies: The relevant framing concerning this work is not in gauging its “credibility,” since the research is sound and at the frontier of our knowledge of the topic. It will not, however, be the last word on the subject. The subject of how climate change affects mid-latitude weather at the synoptic scale (roughly the scale of ~1000 kilometers, i.e., smaller than the tropical scale circulation such as the Hadley cell, but much larger than a tornado for instance) is complex for a number of reasons. One reason is that these are some of the “noisiest” regions on the planet, somewhat less so in summer than in winter, but still subject to considerable internal variability. Therefore, for problems at the synoptic scale, it is often the case that initial condition uncertainty is of more importance than the expected forced component. Indeed, it is well known that 50 realizations of weather in a suite of model runs will not be in phase with reality’s weather, but even decadal trends in dynamical aspects of the mid-latitude atmosphere may differ among the 50 individual members of the model ensemble. Tim Woollings Lecturer, University of Oxford: This article has reported on this story well. The ideas in the new study are interesting, but much more detailed work on this is required in the future. I agree with the quote from John Fyfe that this study is really at the start of something rather than the end. I think climate scientists in general have very diverse views on this theory, but this is well reported in this article. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from the article; comments and replies are from the reviewers. As the climate warms, the Arctic is warming faster than the rest of the globe, potentially impacting the strength of the jet stream, which would have implications for midlatitude weather extremes. However, uncertainty remains regarding the magnitude and mechanisms of this effect, as it is at the frontier of scientific knowledge. “The Northern Hemisphere jet stream […] flow is stronger when that temperature difference is large. But when the Arctic warms up faster than the equator does […] the jet stream’s flow can become weakened and elongated. That’s when you can get the resultant weather extremes.” Daniel Swain Climate Scientist, University of California, Los Angeles: This is an accurate and succinct description of the primary hypothesized mechanism involved in the Arctic/mid-latitude weather linkage. Jim Kossin Research Scientist, NOAA's Center for Weather and Climate: Very nice description for the lay-audience. “Ever since 2012, scientists have been debating a complex and frankly explosive idea about how a warming planet will alter our weather — one that, if it’s correct, would have profound implications across the Northern Hemisphere and especially in its middle latitudes” Jim Kossin Research Scientist, NOAA's Center for Weather and Climate: This is a somewhat misleading intro. The debate has been focused on winter storms (as Mooney discusses below), and these new results are strictly for boreal summer/spring. “a warming planet causes our weather to become more stuck in place” Daniel Swain Climate Scientist, University of California, Los Angeles: This claim is somewhat overly confident given the available evidence. Observational studies (e.g. Francis and Vavrus 2015*) do indeed suggest that the “waviness” of the jet stream and subsequently the propensity for weather patterns to become more persistent has increased in certain regions and during certain seasons, although this is not universally true. There is also emerging evidence that the rapid warming of the Arctic may be playing a role in creating the conditions favorable for weather patterns to become “stuck in place”—a hypothesis that the new Mann et al. 2017* paper discussed in the article supports. The connections between amplified Arctic warming and mid-latitude weather extremes remains a very active area of scientific research (Overland et al. 2016*), however, and considerable uncertainty regarding the magnitude and mechanisms of this effect remain. Francis and Vavrus (2015) Evidence for a wavier jet stream in response to rapid Arctic warming, Environmental Research Letters Mann et al (2017) Influence of Anthropogenic Climate Change on Planetary Wave Resonance and Extreme Weather Events, Scientific Reports Overland et al (2016) Nonlinear response of mid-latitude weather to the changing Arctic, Nature Climate Change “This basic idea has sparked half a decade of criticism and debate, and at the cutting edge of research, scientists continue to grapple with it. And now, a new study once again reinforces one of its core aspects.” Daniel Swain Climate Scientist, University of California, Los Angeles: This is an accurate framing of the (sometimes contentious) ongoing scientific conversation regarding linkages between Arctic warming and mid-latitude weather. “‘This study goes beyond statistical correlations and explores a specific process that can plausibly explain how enhanced high-latitude warming trends may trigger remote weather impacts,’ he said.” Jim Kossin Research Scientist, NOAA's Center for Weather and Climate: Yes, this is the key here. The study is a step toward physically reconciling a linkage that’s only been described statistically. “But other scientific authors have expressed considerable skepticism of these kinds of ideas in the past. A recent study in Nature Geoscience, for instance, called into question whether the Arctic’s melting, and in particular its sea ice loss, has been causing winter cooling over Eurasia, another idea that has been swept up in the debate over the jet stream and weather extremes.” Jim Kossin Research Scientist, NOAA's Center for Weather and Climate: Again, the debate has been about Arctic amplification and winter storm behavior, so this is somewhat misleading. It gives the impression that the new study tacitly pushes the debate about the winter storms toward the Francis/Vavrus side. “‘I do not believe that this theory is fully developed or that the implications have been fully explored, but I do think that Mann et al. study is a very good start.’” Christopher Colose Research Scientist, SciSpace LLC, NASA Goddard Institute for Space Studies: I agree with this. There are many competing components involved in how the jet stream will change in the future, and changing pole-to-equator temperature gradients is just one (in fact, the pole-to-equator temperature gradient increases near the tropopause, complicating the physics). Elizabeth Barnes and James Screen have a good essay here that serves as a useful entry point into these complications. Jennifer Francis Senior Scientist, Woods Hole Research Center: I disagree that the study is only a beginning. The hypothesis that connects quasi-resonance with summer extreme weather, along with evidence to support it, began with Petoukhov et al (2013)*, which was then expanded upon by Coumou et al (2014)*, Kornhuber et al (2016)*, Petoukhov et al (2016)*, and now Mann et al (2017)*. Clearly there is more to learn, but in my view, we are well down the road to understanding this mechanism and identifying its signature in extreme weather. Petoukhov et al (2013) Role of quasiresonant planetary wave dynamics in recent boreal spring-to-autumn extreme events, PNAS Coumou et al (2014) Quasi-resonant circulation regimes and hemispheric synchronization of extreme weather in boreal summer, PNAS Kornhuber et al (2016) Evidence for wave resonance as a key mechanism for generating high-amplitude quasi-stationary waves in boreal summer, Climate Dynamics Petoukhov et al (2016) Quasiresonant amplification of planetary waves and recent Northern Hemisphere weather extremes, PNAS Mann et al (2017) Influence of Anthropogenic Climate Change on Planetary Wave Resonance and Extreme Weather Events, Scientific Reports"
https://science.feedback.org/review/analysis-record-breaking-climate-change-pushes-world-uncharted-territory-damian-carrington-guardian/,1.5,"The Guardian, by Damian Carrington, on 2017-03-20.",,"""Record-breaking climate change pushes world into ‘uncharted territory’""",,,,,"This article in The Guardian describes a “State of the Global Climate” report for 2016 recently released by the World Meteorological Organization (WMO). The report highlights observations of global temperature, sea ice extent, and sea level rise, as well as notable weather patterns. Scientists who reviewed the article found that it accurately described climate trends and events mentioned in the WMO report, including record global warmth and notably low sea ice extents at both poles.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Timothy Osborn Professor, University of East Anglia, and Director of Research, Climatic Research Unit: Overall, this is an accurate and well-supported presentation of the significant nature of climate in 2016. I have highlighted a couple of statements that are overly confident/overstated, but most of the article is fine. Andrew King Research fellow, University of Melbourne: The article clearly and concisely documents some of 2016’s climate extremes and puts them in the context of the warming trend. Daniel Swain Climate Scientist, University of California, Los Angeles: Overall, the article accurately summarizes key points from the WMO report and places recent record-breaking climate events (such as unprecedented global heat and sea ice loss) into reasonable longer-term context. James Renwick Professor, Victoria University of Wellington: An excellent summary, mostly based on a report from the authoritative World Meteorological Organization. Some of the discussion (such as around sea level rise) cuts a few corners. Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: In general, the article is scientifically accurate and does not misrepresent things, although to be critical, given the title and angle of the piece it might be better to focus more on observational data and measurements from 2017, rather than citing many observations from 2016. Another possible criticism is that the piece also relies heavily on quotes and opinions from scientists rather than objective datasets or new graphic representations of those datasets. There aren’t many of the measurements that the WMO have cited included in the report, for example. Aimée Slangen Researcher, Royal Netherlands Institute for Sea Research (NIOZ): I think the article gives an accurate view of the WMO report, and it refers to other sources/papers to support the claims. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from the article; comments and replies are from the reviewers. 1.Human-caused global warming (along with El Niño conditions) lifted 2016 to the warmest year on record. “Global warming is largely being driven by emissions from human activities, but a strong El Niño – a natural climate cycle – added to the heat in 2016.” James Renwick Professor, Victoria University of Wellington: Yes, as stated in the last IPCC report, human emissions of greenhouse gases have been the dominant driver of climate change since the mid-20th century. No other changes (such as the output of the Sun) can adequately explain the observed warming. “But scientific research indicates the world was last this warm about 115,000 years ago and that the planet has not experienced such high levels of carbon dioxide in the atmosphere for 4m years.” Timothy Osborn Professor, University of East Anglia, and Director of Research, Climatic Research Unit: This statement is overly confident and not based on a broad consensus in the literature. Even the cited study states “we cannot be certain that the current year is warmer than any single year earlier in the Holocene due to centennial smoothing of the Holocene stack and original resolution of the underlying proxy records”. The most recent IPCC assessment indicates only moderate confidence that 1983-2012 was the warmest 30-year period in the last 1,400 years and limited this to the Northern Hemisphere rather than the global average. Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: Actually, some of the more recent estimates* have suggested that we may have crossed over the 400 ppm threshold briefly as recently as 2.4 million years ago, and again at 2.9 million years ago. (see Martinez-Boti et al.*). I think climate scientists typically think of the Pliocene (between about 5.3 and 2.6 million years ago) as being the last time period where CO2 may have been more or less permanently above the 400 ppm threshold though, so perhaps this is what they are referring to here. It might be advisable to tidy up the terminology a little here nonetheless. Martinez-Boti et al (2015), Plio-Pleistocene climate sensitivity evaluated using high-resolution CO2 records, Nature James Renwick Professor, Victoria University of Wellington: At the last interglacial period 115,000 years ago, increased solar intensity was responsible for the added warmth, but today’s high CO2 was last seen in the atmosphere 3-5 million years ago. At that time, global mean temperatures were a couple of degrees higher than present, and sea levels were several metres higher than present. “‘With levels of carbon dioxide in the atmosphere consistently breaking new records, the influence of human activities on the climate system has become more and more evident,’ said Taalas.” Mitch Lyle Professor, Sr. Research, Oregon State University: Readers should also be aware of the decades-long lag between the stabilization of CO2 in the atmosphere and the stabilization of CO2-induced warming. The planet will continue to heat because ocean temperatures will not yet be in equilibrium with the atmosphere. 2. Sea ice extent in both the Arctic and Antarctic have been exceptionally low in recent months. “El Niño is now waning, but the extremes continue to be seen, with temperature records tumbling in the US in February and polar heatwaves pushing ice cover to new lows.” Andrew King Research fellow, University of Melbourne: The El Niño pattern of sea surface temperatures waned quite a long time ago, with neutral conditions by mid-2016. The effects of the El Niño on the atmosphere persisted through the year, though. Daniel Swain Climate Scientist, University of California, Los Angeles: The fact that numerous high temperature and low sea ice records are still being exceeded in 2017, despite the lack of El Niño conditions in the Pacific Ocean, is indeed a testament to the increasingly strong human fingerprint upon global weather and climate events. James Renwick Professor, Victoria University of Wellington: This is especially striking in the Antarctic where sea ice extent has been increasing gradually for many years. We are now seeing historic lows in sea ice extent. Aimée Slangen Researcher, Royal Netherlands Institute for Sea Research (NIOZ): Decreasing sea ice extent has been mostly observed in the Arctic, but now also the Antarctic is showing declining sea ice extent. See this page for up to date observed sea ice extent and area. “‘Arctic ice conditions have been tracking at record low conditions since October, persisting for six consecutive months’” Timothy Osborn Professor, University of East Anglia, and Director of Research, Climatic Research Unit: Yes, this is supported by the observations, available at the NSIDC website. “‘The Arctic may be remote, but changes that occur there directly affect us. The melting of the Greenland ice sheet is already contributing significantly to sea level rise, and new research is highlighting that the melting of Arctic sea ice can alter weather conditions across Europe, Asia and North America.’” Daniel Swain Climate Scientist, University of California, Los Angeles: There is indeed observational evidence that melting of the Greenland ice sheet, which contributes to global sea level rise, has accelerated in recent years. While scientists are still intensively investigating the details, it is also true that recent research* suggests that the loss of Arctic sea ice will mostly likely influence weather patterns in mid-latitude regions (including much of Europe, Asia, and North America). Screen (2017)Far-flung effects of Arctic warming, Nature Geoscience 3.The article also mentions sea level changes, notable heat waves, and some of the societal implications of continued global warming. “The WMO’s assessment of the climate in 2016, published on Tuesday, reports unprecedented heat across the globe, exceptionally low ice at both poles and surging sea-level rise.” Timothy Osborn Professor, University of East Anglia, and Director of Research, Climatic Research Unit: “Surging” suggests that the faster sea level rise in 2016 has continued, whereas the surge was between Nov 2014 and Feb 2016, as indicated in WMO’s statement and in the data. “Global sea level rise surged between November 2014 and February 2016, with the El Niño event helping the oceans rise by 15mm.” James Renwick Professor, Victoria University of Wellington: A large part of this rise is related to the transition from La Niña to El Niño. The background rate of global sea level rise is still between 3-4mm per year. “Final data for 2016 sea level rise have yet to be published.” Aimée Slangen Researcher, Royal Netherlands Institute for Sea Research (NIOZ): Agreed, and the causes and reasons will need to be disentangled (El Niño/anthropogenic/other; ice/ocean/other). The total global mean sea-level record is publicly available through NASA’s website. “For example, the Arctic heatwaves are made tens of times more likely and the soaring temperatures seen in Australia in February were made twice as likely.” Andrew King Research fellow, University of Melbourne: This statement is referring to rapid attribution analyses that were conducted by the World Weather Attribution group. We found that the Arctic heat of late 2016 was made much more likely by human-induced climate change (although it remains a very unusual event in the current climate). In another analysis, we found the February heatwave in New South Wales was at least twice as likely to occur because of climate change. “‘Continued investment in climate research and observations is vital if our scientific knowledge is to keep pace with the rapid rate of climate change.’” James Renwick Professor, Victoria University of Wellington: Correct. We are learning as we go, observing how the climate is changing, but more effort is required to keep up with changes and to understand the physical processes at play. “Our children and grandchildren will look back on the climate deniers and ask how they could have sacrificed the planet for the sake of cheap fossil fuel energy, when the cost of inaction exceeds the cost of a transition to a low-carbon economy,’ Watson said.” Valentina Bosetti Professor, Bocconi University: There are large uncertainties surrounding the cost of inaction (i.e., what would be the monetary consequences of adapting to climate change were we not to mitigate its causes and keep emitting as we are doing today). Some of the physical impacts are estimated through projections which may be imperfect. There is large disagreement about what discount rate to use to value future climate damages1. Many of the consequences are simply hard to translate in monetary terms (non-market impacts). Some of the impacts may be nonlinear. This has lead multiple authors to consider abatement as a valuable tail-hedge insurance investment2,3. 1. Heal and Millner (2014) Agreeing to disagree on climate policy, PNAS 2. Weitzman (2014) Fat Tails and the Social Cost of Carbon, American Economic Review: 3. Drouet, Bosetti, and Tavoni (2015) Selection of climate policies under the uncertainties in the Fifth Assessment Report of the IPCC, Nature Climate Change"
https://science.feedback.org/review/great-barrier-reef-coral-climate-change-dieoff-the-new-york-times-damien-cave-justin-gillis/,1.8,"The New York Times, by Damien Cave, Justin Gillis, on 2017-03-15.",,"""Large Sections Australia’s Great Reef Are Now Dead, Scientists Find""",,,,,"The New York Times published an article on coral bleaching and mortality in the Australian Great Barrier Reef and the influence of climate change. Scientists who reviewed the article deemed it largely accurate. While last year saw a record bleaching event that ended up damaging a record number of corals in the region. Severe bleaching has continued for a second consecutive year, which is unprecedented. While natural temperature fluctuations (due to El Niño, for example) have always occurred, they are now superimposed on a warmer background due to human-induced global warming. That causes mass coral bleaching to happen more frequently. Under a business-as-usual scenario of greenhouse gas emissions, coral reef ecosystems are expected to undergo major losses as their slow development and habitat requirements prevents fast migration towards cooler regions.See all the scientists’ annotations in context This is part of a series of reviews of 2017’s most popular climate stories on social media.GUEST COMMENTS: Ove Hoegh-Guldberg Professor and Director, Global Change Institute, University of Queensland: This is an important article that relates the latest science. Even though people may find it shocking, we are facing a serious downward trend in the world’s largest continuous coral reef system. John Bruno Professor, The University of North Carolina at Chapel Hill: Overall, this was an accurate article. There were three sentences that was just a tad off—to be clear, these are minor quibbles (see below). Simon Donner Associate Professor, The University of British Columbia: The article accurately depicts the scientific consensus on climate change and coral bleaching. Mark Eakin Scientist, Coordinator of NOAA’s Coral Reef Watch, National Oceanic and Atmospheric Administration: It is a very nice article. A couple of spots are a bit overstated but this article appears well-researched and carefully worded. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from the article; comments and replies are from the reviewers. 1.Australia’s Great Barrier reef experienced an extensive coral bleaching event last year dueto warming oceans. “Huge sections of the Great Barrier Reef, stretching across hundreds of miles of its most pristine northern sector, were recently found to be dead, killed last year by overheated seawater.” For validation, see our previous analysis of an article in USA Today titled “Australia’s Great Barrier Reef has worst coral die-off ever”. “An additional kick was supplied by an El Niño weather pattern that peaked in 2016 and temporarily warmed much of the surface of the planet, causing the hottest year in a historical record dating to 1880.” John Bruno Professor, The University of North Carolina at Chapel Hill: This is a very common misconception even among scientists. The warming, bleaching, and coral loss is 100% due to greenhouse gas emissions, not the ENSO cycle and the fact that we were in a peak of the El Niño phase in early 2016. The Great Barrier Reef has experienced El Niño events for thousands of years, yet bleaching wasn’t observed there until 1998 when ocean warming pushed ocean temperatures just above the bleaching threshold. 2. Some corals could potentially migrate to cooler waters, but the rapid pace of warming means most coral will be lost. “The global reef crisis does not necessarily mean extinction for coral species. The corals may save themselves, as many other creatures are attempting to do, by moving toward the poles as the Earth warms, establishing new reefs in cooler water.” Simon Donner Associate Professor, The University of British Columbia: Minor quibble: the article mentions corals potentially migrating towards the poles. While coral species may spread poleward as the ocean warms, it takes many years for the reef structure to grow, thus the habitat for other reef species may not be easily recreated. Mark Eakin Scientist, Coordinator of NOAA’s Coral Reef Watch, National Oceanic and Atmospheric Administration: This is rather overstated. While some weedy species may migrate poleward, studies have shown that corals cannot move to much higher latitude due to other factors, such as the light corals require for photosynthesis and skeletal growth. Higher latitude corals will also be restricted to shallow water where they are more susceptible to cold stress. Kleypas et al (1999) Environmental Limits to Coral Reef Development: Where Do We Draw the Line?, American Zoologist “If water temperatures stay moderate, the damaged sections of the Great Barrier Reef may be covered with corals again in as few as 10 or 15 years” John Bruno Professor, The University of North Carolina at Chapel Hill: First, they aren’t moderate now. If they were to decrease and not exceed the bleaching threshold for another few decades, there would be some coral recovery. Second, 10-15 years is a big stretch. There would be some recovery, but not total recovery, especially of very long-lived slow-growing species. “Within a decade, certain kinds of branching and plate coral could be extinct, reef scientists say, along with a variety of small fish that rely on them for protection from predators.” John Bruno Professor, The University of North Carolina at Chapel Hill: I think it is very unlikely any corals would be extinct in a decade. The problem isn’t threat of extinction, its loss of habitat for other critters when corals bleach and die. The corals become less dense, but there will still be many millions of colonies for most species."
https://science.feedback.org/review/why-are-climate-change-models-so-flawed-because-climate-science-is-so-incomplete-jeff-jacoby-boston-globe/,-2,"The Boston Globe, by Jeff Jacoby, on 2017-03-14.",,"""Why are climate-change models so flawed? Because climate science is so incomplete""",,,,,"An article by Boston Globe columnist Jeff Jacoby argues that climate science is too “incomplete” to determine whether human-caused emissions of greenhouse gases like carbon dioxide could be responsible for global warming. The column defended US EPA Administrator Scott Pruitt’s recent statement that he “would not agree that [human activity is] a primary contributor to the global warming that we see”—a statement scientistsreviewed and found to be incorrect. Scientists who analyzed Jacoby’s column found that it is inaccurate, misleading, and uses flawed reasoning to support its central claims. In reality, CO2’s role in the climate system is well understood, and this fundamental knowledge informs the determinations that humans are responsible for modern climate change, and that continued greenhouse gas emissions will cause further warming.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. James Screen Associate Professor, University of Exeter: This is a highly inaccurate article that makes a number of false and intentionally misleading claims. The weight of scientific evidence (summarised in the IPCC reports) shows that greenhouse gas emissions are the dominant cause of observed global warming. The claim that climate models “always predict far more warming” is demonstrably false. The discussion of complexity is intended to mislead: the fact that the climate system is incredibly complex does not mean we don’t understand key aspects of how it functions. Mitch Lyle Professor, Sr. Research, Oregon State University: Jacoby used a flurry of words to claim that models did not work. He set up a straw man about complexity that was irrelevant and never actually examined real climate models. Dan Chavas Assistant Professor, Purdue University: The article is full of logical fallacies: just because a system has many moving parts does not mean it is unpredictable. Alexis Tantet Postdoctoral researcher, Hamburg University, Meteorologisches Institut: The facts given by the author regarding the skills of climate models and the state of the art are mostly wrong. The most important processes are not understood by the author and his logic is flawed William Seviour Senior Lecturer, University of Exeter: This article combines tired and regularly-debunked climate myths with faulty reasoning to support a statement which is ungrounded in scientific reality. James Renwick Professor, Victoria University of Wellington: One of the most egregious pieces of misinformation I have seen in the media in years. Ilissa Ocko Climate Scientist, Environmental Defense Fund: This article employs flawed reasoning mixed with inaccurate statements to create a false impression of climate scientists’ state of understanding. Andreas Schmittner Associate Professor, Oregon State University: The article contains major scientific inaccuracies and it omits important information. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from the article; comments and replies are from the reviewers. 1. It is clear that humans are causing climate change through emissions of greenhouse gases like carbon dioxide, which acts as a control knob on the climate system. “CO2 is certainly a heat-trapping greenhouse gas, but hardly the primary one: Water vapor accounts for about 95 percent of greenhouse gases. By contrast, carbon dioxide is only a trace component in the atmosphere: about 400 ppm (parts per million), or 0.04 percent.” Christopher Colose Research Scientist, SciSpace LLC, NASA Goddard Institute for Space Studies: First, it is true that water vapor constitutes the bulk of Earth’s present-day greenhouse effect (measured in terms of infrared absorption). Quantitatively, however, Jacoby is off by quite a bit. In fact, water vapor constitutes ~50% of the terrestrial greenhouse effect, not 95% (see here*). Clouds (solid and liquid water that form when the vapor condenses) constitute another ~25%, but CO2 contributes to almost all of the remaining fraction (only ~5% or so from all of the other combined gases). This is because CO2 still absorbs well in spectral regions where water vapor doesn’t, and also because the upper troposphere is very dry; the ability to absorb intense surface emission and re-emit it at colder, higher layers of the atmosphere is critical for the maintenance of a planetary greenhouse effect. Secondly, the water vapor greenhouse effect is not independent of the CO2 in the atmosphere. Jacoby stresses that CO2 is only a trace component of the atmosphere, an argument that is irritatingly unoriginal and provides useless context when describing the flow of radiation through the atmosphere. As before, CO2 accounts for ~20% of Earth’s greenhouse effect. N2 and O2 account for nearly all of Earth’s atmospheric mass. However, if the atmosphere were purely N2 and O2, the planet would likely be in a snowball state due to the lack of greenhouse trapping. This is where the equations of radiative transfer must be applied, rather than a naive intuition about proportions. Schmidt et al (2010)Attribution of the present-day total greenhouse effect,Journal of Geophysical Research: Atmospheres. Mark Zelinka Research Scientist, Lawrence Livermore National Laboratory: Another helpful quote comes from this article: “The contribution of CO2 to the greenhouse effect, considerable though it is, understates the central role of the gas as a controller of climate. The atmosphere, if CO2 were removed from it, would cool enough that much of the water vapor would rain out. That precipitation, in turn, would cause further cooling and ultimately spiral Earth into a globally glaciated snowball state. It is only the present of CO2 that keeps Earth’s atmosphere warm enough to contain much water vapor.” I like to think of CO2 as analogous to a military commander and water vapor as analogous to an army of foot soldiers. Even though the water vapor foot soldiers do most of the fighting, the CO2 commander sends the army to battle. William Seviour Senior Lecturer, University of Exeter: While it is true that carbon dioxide constitutes about 400 ppm (or 0.04%) of the atmosphere, the implication that this means it is insignificant in Earth’s climate is incorrect. It is the ability of a gas to absorb radiation, and so affect energy balance of the Earth, not its concentration, which is important. This effect on Earth’s energy balance can be quantified by the radiative forcing (RF); a positive RF means a surface warming effect and a negative RF a cooling. The figure below, from the 2013 IPCC report shows estimates of RF for a range of factors which have influenced climate from 1750-2011. As can be seen, increasing carbon dioxide concentrations have the largest RF and therefore the largest impact on climate. I also stress that knowledge of the important role of carbon dioxide (despite its low concentration) in Earth’s climate is not new, and dates back to the work of Tyndall, Arrhenius, and others in the 19th century. “Moreover, its warming impact decreases sharply after the first 20 or 30 ppm. Adding more CO2 molecules to the atmosphere is like painting over a red wall with white paint — the first coat does most of the work of concealing the red. A second coat of paint has much less of an effect, while adding a third or fourth coat has almost no impact at all.” Christopher Colose Research Scientist, SciSpace LLC, NASA Goddard Institute for Space Studies: Jacoby emphasizes the logarithmic nature of how CO2 affects the energy balance of Earth, and hence surface temperature (i.e., going from 10 ppm of CO2 to 11 ppm would have a much larger impact than going from 300 to 301 ppm). This is correct, but has been known for well over half a century now, and is fully accounted for in even simple estimates of future warming. This is therefore a distraction. Andreas Schmittner Associate Professor, Oregon State University: The effects of CO2 do not decrease sharply after the first 20 or 30 ppm. The radiative effects of CO2 are logarithmic, so they increase slightly less the higher CO2 gets but they don’t decrease sharply. Ilissa Ocko Climate Scientist, Environmental Defense Fund: This is flawed reasoning as it is not a sensible analogy for how the greenhouse effect works. The science is more complex: Namely, radiation from the surface at a warmer temperature is absorbed in the layers above which are at a colder temperature; the colder layers emit less radiation so that there is a net loss of radiative energy escaping to space from the atmosphere-surface system as a whole, but coming about due to the “exchange” as formulated. This is true in absorption bands that are transparent and not opaque—i.e., in bands that are not saturated. In bands that are opaque, the radiation emanating from the layer to space represents a “cooling-to-space” and this too represents a “trapping”. In this regard, the lapse-rate and decrease of temperature with height (in the troposphere) are important. The more CO2 that is added to the atmosphere, the more heat that is “trapped” in the climate system, although it is not 1:1 and is instead a logarithmic relationship. However, regardless of the rate, we still have more warming with more CO2—that is unequivocally true. William Seviour Senior Lecturer, University of Exeter: Jacoby links to a blog page which explains the logarithmic relationship of CO2 concentrations and radiative forcing. Contrary to Jacoby’s implication, this is actually a well accepted part of climate science. For instance, see Myhre et al 1998* (table 3), who give detailed estimates of this logarithmic relationship. However, as CO2 concentrations rise, the fraction of CO2 which remains in the atmosphere (rather than being absorbed by the ocean) is projected to increase (see Jones et al 2013*). The net effect is that the relationship between total CO2 emissions and surface temperature is almost linear. See the figure below from the 2013 IPCC report. Myhre et al (1998) New estimates of radiative forcing due to well mixed greenhouse gases, Geophysical Research Letters Jones et al (2013) Twenty-First-Century Compatible CO2 Emissions and Airborne Fraction Simulated by CMIP5 Earth System Models under Four Representative Concentration Pathways, Journal of Climate “There is a popular theory that atmospheric CO2 amplifies the creation of water vapor, thereby increasing warming through a ‘positive feedback loop.’ But that theory so far is mostly speculative; climate projections using models based on it have consistently failed, nearly always predicting far more warming than has occurred” John Fyfe Senior Research Scientist, Canadian Centre for Climate Modelling and Analysis: [John Fyfe was the first author of the paper linked by Jacoby to support this claim] The statement “climate projections using models based on it have consistently failed, nearly always predicting far more warming than has occurred” is false. Climate models reproduced the observed record of global average temperature rise since the middle of the 20th Century. It is true that climate models overestimated the observed rate of warming over the early-21st Century but this was not unexpected. Over this period, and due to a well-known natural fluctuation in the climate system, temperatures over much of the tropical Pacific were cooler than normal. These ocean temperatures have warmed significantly over the past few years. Climate models represent these natural fluctuations in the climate system but do not – by design – reproduce the observed timing except by chance. This is the primary reason why climate models overestimated the rate of global average temperature rise over the early-21st Century. Christopher Colose Research Scientist, SciSpace LLC, NASA Goddard Institute for Space Studies: Jacoby discusses the so-called water vapor feedback, in which warming caused by CO2 (or anything) results in more water vapor in the atmosphere, increasing heating. However, his discussion is confused. First, models are not based on a water vapor feedback. Such a feedback is result, not an assumption. There is no FORTRAN code written that tells a model to increase the water vapor concentration when the CO2 is going up. However, there is incredibly well-established thermodynamics assuring us that a warmer atmosphere can theoretically hold more water vapor. This doesn’t mean it will—after all, deserts are very hot, but not very moist. This is because atmospheric dynamics (especially the rising and sinking motions of air) keep most of Earth’s atmosphere beneath its maximum vapor holding capacity. However, it turns out that observations and complex models (as well as more simple theoretical work) suggest that this degree of “subsaturation” (or relative humidity) doesn’t change much, so the actual water vapor concentration still goes up in a similar way that it would if it just behaved like a simple thermodynamic equation (see e.g., here and here and here)*. Indeed, this has been a robust result going back to at least the 1960s in observational and model-based syntheses of the problem, and is now very well understood. Indeed, CO2 is the fundamental control knob on Earth’s climate over relatively long timescales, since the water vapor concentration is shackled to temperature in a very fundamental way, because the Sun’s output does not change very much except on geologic time intervals, and because CO2 is the principle non-condensing greenhouse gas capable of changing in response to geologic (or anthropogenic) sources and sinks on climate timescales. Pierrehumbert et al (2007) On the relative humidity of the Earth’s atmosphere, The General Circulation Held and Soden (2000) Water vapor feedback and global warming, Annual Review: of Energy and the Environment Chung et al (2014) Upper-tropospheric moistening in response to anthropogenic warming, PNAS Andreas Schmittner Associate Professor, Oregon State University: The water vapor feedback, which is referred to here as “creation of water vapor” but in fact is higher water vapor in a warmer atmosphere, is a basic prediction of thermodynamics, one of the most well-tested branches of physics. Water vapor has been observed to increase*. So, there is nothing speculative about it. The claim that climate models have consistently failed is false. In fact, the contrary is true. Climate model projections from the 1980s have essentially come true. For a recent example see Stouffer and Manabe (2017)*. Chung et al (2014) Upper-tropospheric moistening in response to anthropogenic warming, PNAS Stouffer and Manabe (2017) Assessing temperature pattern projections made in 1989, Nature Climate Change Mark Zelinka Research Scientist, Lawrence Livermore National Laboratory: All available evidence suggests that the atmosphere maintains nearly constant relative humidity, meaning that the absolute concentration of water vapor increases exponentially with temperature. The exponential increase is grounded in fundamental physics known as the Clausius-Clapeyron equation. A particularly clever test of the amplifying water vapor feedback was conducted in response to the Mount Pinatubo eruption in 1991*. If there were no amplifying water vapor feedback, then the global cooling in response to the volcanic eruption would have been much smaller than observed. Soden et al (2002) Global Cooling After the Eruption of Mount Pinatubo: A Test of Climate Feedback by Water Vapor, Science “The science is far from settled.” James Renwick Professor, Victoria University of Wellington: The basic controls on the climate, sunlight and greenhouse gases, have been understood for over a century and are not disputed. The frontiers of climate research are where the debates lie, as with any branch of science. “[Pruitt’s statement] was an accurate and judicious answer” Ilissa Ocko Climate Scientist, Environmental Defense Fund: It is objectively not an accurate answer and is misleading at best. [Pruitt’sstatement has beenreviewed by scientists with Climate Feedback and found to be incorrect.] While it is certainly challenging to determine human influence on the climate, decades of research by tens of thousands of scientists from different institutions all over the world have yielded a nearly unanimous consensus with extreme confidence that humans are the dominant cause of climate change. In fact, scientists have been questioning and researching human influence on the climate for nearly 200 years. Further, we can use techniques similar to the smoking-cancer causality research to prove that humans are mainly responsible and to show that carbon dioxide is the primary control knob for today’s climate change. There is no “tremendous disagreement” or “debate” about this. 2. Earth’s climate system is complex, but the basic processes are well understood, allowing climate scientists to usefully project the impacts of continued greenhouse gas emissions. “Earth’s climate system is unfathomably complex. […] The more variables there are in any system or train of events, the lower the probability of all of them coming to pass. Your odds of correctly guessing the outcome of a flipped coin are 1 in 2, but your odds of guessing correctly twice in a row are only 1 in 4 — i.e., ½ x ½ Extending your winning streak to a third guess is even less probable: just 1 in 8.” James Renwick Professor, Victoria University of Wellington: Yes, it is complex, but not unfathomable. The basics are simple—the energy budget at Earth’s surface is controlled by the intensity of sunlight reaching the ground and the amount of greenhouse gas in the atmosphere. That’s it. This analogy implies everything is happening randomly in the climate system. This is not the case. There is a great deal of structure imposed by the laws of fluid motion and energy transfer, and by the basic geometry and rotation rate of the Earth. Alexis Tantet Postdoctoral researcher, Hamburg University, Meteorologisches Institut: The Earth system is indeed complex with nonlinear interactions between various components on a large range of time and spatial scales. However, some processes are very robust, such as the response of the global energy budget to increased greenhouse gases, so that the surface of the Earth eventually has to warm up in order to reach a radiative balance. The distribution of the heating, the rate of melting of the ice sheets, the changes in the occurrence of extremes, etc. are more difficult to predict and that is why we need state-of-the art global climate models. Last, one should not confuse the weather prediction of an exact meteorological state, limited by the chaotic nature of the system, and climate projections of the statistics of variables in response to forcing, such as the global mean surface temperature sensitivity to greenhouse gases emissions. “The list of variables that shape climate […] would run to hundreds, if not thousands, of elements, none of which scientists would claim to understand with absolute precision.” Mitch Lyle Professor, Sr. Research, Oregon State University: Jacoby is making a laundry list, not trying to understand the issues. He is also confusing the issue by trying to claim that since scientists cannot predict climate change at a given small location at a fixed point in future time that they do not have the ability to generally predict the the future trend. Climate scientists are after the trend. Most of the variables he mentions cause the local climate to deviate to a small extent from the trend. Some, like volcanic activity or El Niño, affect the climate for a small number of years, and then their effect disappears. Christopher Colose Research Scientist, SciSpace LLC, NASA Goddard Institute for Space Studies: The basic argument in the remainder of the article is one of “complexity” and the notion that climatologists cannot perfectly understand thousands of variables, and hence the behavior of the system under investigation. Jacoby is not completely wrong—climate is extremely complex, and poses no shortage of interesting research questions. However, it is sometimes difficult for non-specialists to appreciate the emergent simplicity that can arise in an incredibly complex system. After all, how do we know summer will be warmer than winter, that the top of Mt. Everest is colder than the base, or that Arizona is expected to be on average drier than Florida, or that the equator ought to be hotter than New York, or that the climate will cool following a large volcanic eruption? These statements are not just based on prior observations, but in fact can be predicted by applying fundamental equations to a rotating planet. Part of the beauty in studying atmospheric science is in gaining an appreciation for where complexity is counterbalanced by an almost eerie predictability, much like how the outcome of a single spin in roulette is hopelessly unpredictable (and certainly influenced by every slight detail at the time the dealer releases the ball), but casinos have no problem with such complexity because the statistical behavior of the roulette wheel is well-posed. Similarly, the statistical behavior of the atmosphere, while unsolved, is not actually that complex. The appeal to complexity is a compelling one. Nonetheless, progress has been made in many complex sciences (astrophysics, geology) in which the system under investigation cannot be experimentally isolated, and yet where so much is known. However, it turns out to be incredibly simple to rule out El Niño, volcanic eruptions, soil quality, sunspot cycles, plate tectonics, etc. to the trend in global temperatures since 1950. Just as geologists can inform you of the glacial history of a region, sometimes with little more than a trained eye, CO2 leaves behind “fingerprints” in the atmospheric warming that other “forcing agents” do not. Another perhaps surprising component is that this result is not extremely sensitive to unknown variables. Suppose, for example, that the Andes Mountains were abruptly flattened. This would almost certainly affect important aspects of the global and regional climate, but many of the critical phenomena of the climate system (e.g. that the equator is wet where air rises, that storm tracks develop in the mid-latitudes, the presence of a jet stream, etc.) would still remain. Furthermore, adding CO2 to a “flat-Andes hypothetical Earth” would still result in warming. It’s physics, and it’s unavoidable. It is true that the exact magnitude of future warming, even if we knew future carbon emissions perfectly, is still not known to within even 10%. However, that uncertainty range does not overlap with “very little warming” or “make the planet uninhabitable warming.” In any case, if one’s argument is based on how complex the system is, surely perturbing that complex system is not something they ought to advocate for! “What are the odds that a climate model built on a system that simple would be reliable? Less than 50/50. (Multiplying .95 by itself 15 times yields 46.3 percent.)” James Renwick Professor, Victoria University of Wellington: Again, this assumes that all variables are independent and everything is happening randomly. This is just not the case. Winds, temperatures, pressures, cloud formation, and so on are all bound together in coherent ways by the laws of physics. Alexis Tantet Postdoctoral researcher, Hamburg University, Meteorologisches Institut: This is absolutely not how prediction skills are and should be measured. Assuming that each variable is given the same weight, the initial error would be of 5%. How this error grows with the prediction is a nontrivial problem, which cannot be explained by kindergarten probabilities, but requires observations, theory and modeling. Moreover, the problem of the predictability of fast weather fluctuations become irrelevant for long-term climate projections of statistics in response to forcing. “Is it any surprise that climate-change predictions in the real world — where the complexities are exponentially greater and the exactitude of knowledge much less — have such a poor track record?” William Seviour Senior Lecturer, University of Exeter: One way we can evaluate climate models is their ability to simulate past observed climate changes. The following figure from the 2013 IPCC report shows that they in fact have a good track record in capturing climate change over past century."
https://science.feedback.org/review/claim-new-scientist-humans-responsible-100-warming-mostly-correct/,Mostly correct,"New Scientist, Michael Le Page, 2017-03-08",more than 100 per cent of the warming over the past century is due to human actions,,"Overstates scientific confidence: The statement gives the impression of high confidence in this exact number, while a little more caution is warranted.",The best estimate of the portion of global warming observed since 1950 that is due to human influence is indeed around 100%. There is some uncertainty as to whether humans caused a little bit more or a little bit less than 100% of the warming.,... more than 100 per cent of the warming over the past century is due to human actions. How can it be more than 100 per cent? Because without us the planet would likely have cooled very slightly thanks to natural factors such as volcanic emissions and orbital changes.,,"Andrew King Research fellow, University of Melbourne: While I wouldn’t go quite as far as saying more than 100% of warming is due to human activities (because there are uncertainties on these numbers and it may be just under 100%) the point the writer is trying to make is essentially correct. Without human influences on the climate we would have had virtually no trend in global temperatures so all of the warming since about 1950 can be attributed to the human influence on the climate.Francois-Marie Breon Senior Scientist, Commissariat à l'Energie Atomique: There is no doubt that human activities led to climate warming during the last 100 years. The contribution of natural processes (the sun, volcanoes, natural variability…) is small in comparison. However, there is significant uncertainty on the natural contribution and it is not yet clear whether the Earth would have warmed or cooled during the past century without the anthropogenic perturbation. Thus, the anthropogenic contribution to the observed warming is close to 100%, but it is not demonstrated whether it is larger or smaller than this number.Andreas Schmittner Associate Professor, Oregon State University: I’d say that the statement is mostly correct. The only difference between the statement and the study it is hyperlinked to is that the study considers the temperature trend from 1950 to 2010, so the last 60 years and not the past century as noted in the statement. I’d also note that the cooling due to natural factors is not statistically significant in the study.From the IPCC’s Fifth Assessment Report: “It is extremely likely that more than half of the observed increase in global average surface temperature from 1951 to 2010 was caused by the anthropogenic increase in [greenhouse gas] concentrations and other anthropogenic forcings together. The best estimate of the human-induced contribution to warming is similar to the observed warming over this period.” Figure showing the best estimate of the human-induced contribution to warming between 1951 and 2010. Black lines show confidence intervals."
https://science.feedback.org/review/science-shows-humans-primarily-responsible-climate-change-counter-epa-administrator-scott-pruitts-claim/,Incorrect,"CNBC, Scott Pruitt, 2017-03-09",I would not agree that [carbon dioxide is] a primary contributor to the global warming that we see.,,"Misleading: While there is uncertainty about the precise value of the human contribution to global warming, that uncertainty does not include the possibility that human activities are not the primary contributor. Factually inaccurate: There is no significant scientific disagreement about the fact that human activity is responsible for climate change.",Science clearly shows that the climate change that has occurred since the Industrial Revolution is primarily due to human-caused emissions of greenhouse gases.,"I think that measuring with precision human activity on the climate is something very challenging to do and there’s tremendous disagreement about the degree of impact. So no, I would not agree that it’s a primary contributor to the global warming that we see.",,"This is part of a series of reviews of 2017’s most popular climate stories on social media.Andy Pitman Director of the ARC Centre of Excellence for Climate System Science, The University of New South Wales: Its an incorrect statement because it convolutes three statements. “I think that measuring with precision human activity on the climate is something very challenging to do” This statement is true. It is very challenging, but 30 years of intense effort by a vast array of scientists have done it. “and there’s tremendous disagreement about the degree of impact.” This statement is false in terms of the implications of the decision. That is, there is no scientifically well-informed disagreement that the impact will be significant and should be built into any sensible risk management. It is true that there is disagreement on the degree of impact, but not that the impact will be significant. To be clear, there is agreement that the impact will be very serious, but how very serious is argued. “So no, I would not agree that it’s a primary contributor to the global warming that we see.” That statement is inconsistent with every independent assessment of the scientific literature I have seen, except from organisations set up to deny the science and misinform the public. The statement that global warming is unequivocal is supported by a massive body of work. The main statement comes from the 5th assessment report by the Intergovernmental Panel on Climate Change, a report agreed to by the global scientific community, and by the world’s governments. Shaun Lovejoy Professor, McGill University: Let’s say you are given only three pieces of information: a) The annual average value of the global temperature from 1880 to 1909 b) The atmospheric CO2 concentration for each year c) The effective climate sensitivity With only this, the temperature over the 104 years between 1909 and 2013 could be incredibly well forecast (black line in the figure below), indeed to about an accuracy of ±0.22 °C (purple lines, 90% confidence limits). This tight limit includes the so-called “pause” of the early 2000s. Knowing only the CO2 therefore allows us to predict the temperature more than 100 years into the future. Given that the total change over this time was 1.1 °C, the prediction is correct to within 20%. We know that the CO2 was anthropogenic, therefore its increase was not caused by a change of temperature. We can conclude that CO2 is responsible for much of the change in temperature over the last century. Figure adapted from Lovejoy (2015), Using scaling for macroweather forecasting including the pause, Geophysical Research Letters Ed Hawkins Principal Research Fellow, National Centre for Atmospheric Science: John Tyndall measured the heat absorption properties of various gases, including carbon dioxide, in his laboratory in the 1850s and suggested that changing their atmospheric concentrations would alter the climate. The levels of carbon dioxide have increased ever since and Tyndall’s prediction has become a reality. Global temperatures have risen by about 1°C, causing sea ice and land ice to melt, sea levels to rise, and extreme heatwaves and rainfall to increase. The impacts of increasing levels of carbon dioxide in the atmosphere are being seen already and the risks for the future are considerable unless we stabilise our emissions of greenhouse gases."
https://science.feedback.org/review/scientists-we-know-what-really-causes-climate-james-barrett-the-daily-wire/,-1.5,"The Daily Wire, by James Barrett, on 2017-02-24.",,"""Scientists: Here's What Really Causes Climate Change (And It Has Nothing To Do With Human Beings)""",,,,,"This post at The Daily Wire, which has been widely shared on Facebook, claims that a recent study of variations in Earth’s orbit recorded by 90 million-year-old rocks provides evidence against a human cause of current global warming. Scientists who reviewed the post found that it misrepresented the study’s implications for modern climate change, as well as the timeframes that the study is relevant to. In reality, the gradual cycles in Earth’s orbit are much too slow to be responsible for the warming of the last couple centuries. Climate research has shown that these orbital changes and other natural factors do not explain modern warming. All the reviewers also indicate that the title of the article is not supported by its content.See all the scientists’ annotations in contextUPDATE (07 March 2017): The original article has been edited to correct some of the statements highlighted here. Read moreREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Francois-Marie Breon Senior Scientist, Commissariat à l'Energie Atomique: Although the main body of the article may be a fair description of a scientific paper, the conclusion that anthropogenic climate change is dwarfed by natural variations is extremely misleading and certainly not in the original paper. The original scientific paper discusses climate variations over millions of years. The causes for recent climate change involves processes that are very different. Georg Feulner Senior Scientist, Potsdam Institute for Climate Impact Research (PIK): The reasoning in this biased article is flawed. The fact that orbital variations can cause climate change does not imply “that the role man plays on the planet is dwarfed by natural phenomena”. Chris Brierley Senior Lecturer, University College London: It’s strange how research into how planets orbit within our solar system has ended up being used to downplay the anthropogenic role in climate change. The research is about a geologic time period without ice-ages, yet that seems to be the confused reasoning for the article’s conclusion. The incorrect link to completely different research in the Nature journal about ice-ages betrays this confusion. Geert Jan van Oldenborgh Senior researcher, KNMI (The Royal Netherlands Meteorological Institute): The article misuses a Nature article on a geological process 90 millions years ago to argue the warming of the past century is not anthropogenic. It seems the reasoning is ideologically motivated rather than based on reality. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from the article; comments and replies are from the reviewers. 1.The timing of past “ice ages” was governed by slow-changing cycles in Earth’s orbit, but these cycles can not explain recent warming, which has been caused by human activities, instead. “While evidence that the earth’s orbital variations impact radiation levels and thus global temperatures does not of course mean that man is not in some way impacting the climate, studies like these highlight that the role man plays on the planet is dwarfed by natural phenomena utterly out of our control.” Geert Jan van Oldenborgh Senior researcher, KNMI (The Royal Netherlands Meteorological Institute): Over geological time scales, indeed. However, the rise in temperature of 1 degree Celsius over the last two hundred years is not on a geological time scale, and is not caused by natural phenomena out of our control as suggested here. Both from the negative (there are no natural forcings on the climate that would have produced such heating over the last century) and from the positive (the heating is pretty much what we expect from greenhouse gases minus aerosols) the evidence is very strong that humans are responsible for most of the trend over the last 100 years. Chris Brierley Senior Lecturer, University College London: I’m not sure how they come to this conclusion. The increase in global temperature from the depth of the last glacial (22,000 years ago) to preindustrial times is about 4.5°C. This is less than the warming projected for the end of the century, if we choose to ignore man’s responsibility as the author suggests. Clearly if we do act to limit the warming to 2°C, then the glacial change would be bigger than it, but the timespans involved mean that current climate change is still a happening at a faster rate. “[…]an explanation of the fluctuations of the earth’s temperatures that global warming alarmists are going to make sure to bury: The cycle of changes in the climate over the millennia is a result of changes in the amount of solar radiation, in part caused by small changes in the orbits of Earth and Mars.” Chris Brierley Senior Lecturer, University College London: This is the accepted explanation for periodic past changes in Earth’s climate. We spend multiple classes explaining this to our students. We certainly do not bury it. “changes in the climate over the millennia” Geert Jan van Oldenborgh Senior researcher, KNMI (The Royal Netherlands Meteorological Institute): This is false. The article is about changes in climate 90 million years ago at geological time scales, much slower than the “millennia” referred to here. 2.The article seems to confuse two different studies. “While the notion that the impact on earth’s orbital cycle on solar radiation levels is the most significant factor determining global temperatures is anything but new, the team of scientists seem to have tied the phenomenon to planetary orbits in a more concrete manner than previous studies.” Chris Brierley Senior Lecturer, University College London: I can’t help but think this sentence really refers to a research article called “A simple rule to determine which insolation cycles lead to interglacials” by Tzedakis and colleagues, rather than “Theory of chaotic orbital variations confirmed by Cretaceous geological evidence” by Ma, Meyers & Sageman. “In an article summarizing the scientists’ findings, which were originally published this week in the journal Nature, the University of Wisconsin-Madison notes that the study ‘provides the first hard proof for what scientists call the ‘chaotic solar system,’ a theory proposed in 1989 to account for small variations in the present conditions of the solar system.” Chris Brierley Senior Lecturer, University College London: Neither the linked article nor this Daily Wire news item relate to the research linked in Nature [which is the Tzedakis et al paper rather than Ma et al]."
https://science.feedback.org/review/heres-why-its-so-frickin-hot-right-now-andrew-freedman-mashable/,1.3,"Mashable, by Andrew Freedman, on 2017-02-24.",,"""Here’s why it's so frickin’ hot right now""",,,,,"This article at Mashable discusses the number of high temperature records set in the United States during the month of February. While short-term weather events are not indicative of climate changes, the statistics of weather events across regions and over time doreflect climatic trends. As the climate warms due to human activities, daily high temperature records will be set more frequently than new low temperature records. The scientists who reviewed this article found that it accurately described recent US weather within this context.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Andrew King Research fellow, University of Melbourne: The article provides an overview of the recent record-breaking warm weather in parts of the US. It is well-researched and points to the most relevant literature in the field. In the absence of a specific event attribution study we cannot quantify the role of climate change in this event. However, by pointing to the long-term trend in the ratio of record-setting, the article does a nice job of putting this event in the context of a warming world. Ryan Sriver Associate Professor, University of Illinois: This is a well-written piece that provides a nice summary of the current warm events in the bigger context of climate change. I caution against using a single month of data to support claims about climate change impacts on extremes, but the discussion about record highs outpacing record lows is a good one and provides strong evidence for influence of global warming on regional weather. Scott Robeson Professor, Indiana University: This is a solid article that accurately describes recent record warm events in the US. A global perspective would have helped, as the US represents just 4% of the area of the Northern Hemisphere. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from the article; comments and replies are from the reviewers. 1.The US has experienced an increasing number of record highs vs. record lows over the last few decades. Such trend in statistics provides strong evidence for a warming climate. “Taken as a whole, the month-to-date in the U.S. has seen a ridiculously lopsided ratio of daily record highs to daily record lows, which is a key indicator of short-term weather variability and, over the longer term, human-caused climate change.” Andrew King Research fellow, University of Melbourne: This is an important qualification. We expect in a stationary climate that we would have some periods with more record hot temperatures than record lows and vice versa. Over an extended period of time, in a stationary climate, this ratio would average to be one. It’s because this pattern of more record hot than record cold temperatures has persisted over recent decades that allows us to link this trend to climate change. “As the planet warms in response to the buildup of greenhouse gases in the atmosphere, the ratio of high temperature records compared to low temperature records has become more skewed. If the climate weren’t warming, that long-term ratio should average out to about 1-to-1.” Ryan Sriver Associate Professor, University of Illinois: The shift towards more warm extremes suggests the underlying distributions (weather) are changing. The climatology is shifting towards higher temperatures. “While transient weather variability is playing a key role here, the widespread record warmth across the U.S. so far this year is part of a long-term trend toward more warm temperature records versus cold ones.” Scott Robeson Professor, Indiana University: The author correctly points out that it’s the superposition of persistent, extreme jet-stream fluctuations and the background of rising temperatures that is leading to more record warm extremes. Whether the extreme jet-stream fluctuations themselves are part of the changing winter climate is still unclear. Andrew King Research fellow, University of Melbourne: This paper is the first I’m aware of to highlight this effect over the US: Meehl et al (2009) Relative increase of record high maximum temperatures compared to record low minimum temperatures in the U.S., Geophysical Research Letters Ryan Sriver Associate Professor, University of Illinois: I agree that the year-to-year natural variability can contribute significantly to extreme temperatures, especially at local or regional scales. The disproportionate number of record highs versus record lows over several years-to-decades suggests that the seasonal temperature distributions (or likelihoods of experiencing a given extreme during any given season) are shifting toward warmer temperatures consistent with long-term anthropogenic global warming. How continued warming affects the tails of the distributions (beyond just shifting the location) is an interesting and open question. 2.February saw some unusual warmth in the US. “So far this month, there have been nearly 5,000 daily record highs set or tied, compared to just 42 daily record lows.” Scott Robeson Professor, Indiana University: It is very appropriate to look at this ratio of record highs versus record lows, as the climate stations themselves have different periods of records and therefore different expected rates of records (all are “long term” and have at least 30 years of data but some have much longer periods of record). But, one would still expect a one-to-one ratio of record highs to record lows in a stationary climate regime. “In Albany, New York, the high temperature of 74 degrees on Thursday was the warmest temperature on record for any day during the months of December, January and February.” Scott Robeson Professor, Indiana University: Seasonal records like this are even more impressive and much more robust as they are composed of much larger sample sizes than the individual day’s values."
https://science.feedback.org/review/worlds-coral-reefs-severely-threatened-climate-change-human-impacts-abc-story-notes/,Mostly correct,"ABC News, Greg Hassall, Rebecca Latham, 2017-02-23","90 per cent of the world's coral reefs will disappear in the next 35 years due to coral bleaching induced by global warming, pollution and over-development.",,"Imprecise: Clarification required: It is not certain that these corals will necessarily be dead by 2050, but instead are likely to be unsustainable, i.e., susceptible to dying after heat stress events. Somewhat misleading in that it might be understood as if the reef (the platform of rock and mineral skeletons on which corals and other species live) will physically disappear, while in reality the statement should be about the death of corals.","About half of the coral that were alive in preindustrial times have already been lost, and most corals living on reefs today are likely to be unsustainable by the end of this century.","Scientists estimate 90 per cent of the world's coral reefs will disappear in the next 35 years due to coral bleaching induced by global warming, pollution and over-development.",,"Katrin Meissner Professor, University of New South Wales: This is a fair statement, based on several peer-reviewed studies. For example, Meissner et al. (2012)* conclude that: “Regardless of the [greenhouse gas] concentration pathway” (RCP 3PD, RCP 4.5, and RCP 8.5), “virtually every reef considered in this study (>97%) would experience severe thermal stress by year 2050.” This paper considered a range of future concentration pathways from the most aggressive “business as usual” to the most optimistic (RCP 3PD, which peaks at 440 ppm), and calculated the probability of reoccurring severe bleaching events at the locations of major coral reefs worldwide. The analysis was based on future projections simulated with a climate model and superimposed natural climate variability (El Niño Southern Oscillation). “Severe thermal stress” means that a coral reef does not have enough time to recover between two severe bleaching events. Furthermore, a high percentage of reefs will also be stressed by ocean acidification by 2050 (see figure below). When we also add local pollution, increased nutrient and sediment loading, and over-development as stress factors, we can conclude that ABC’s statement is likely an underestimation. Figure – Open ocean surface seawater aragonite saturation. Left column shows the RCP 3PD simulation (year 2030 (a), year 2050 (c), and year 2100 (e)); right column the RCP 8.5 simulation (year 2030 (b), year 2050 (d), and year 2100 (f)). Reefs in blue have a less-than-10% probability of experiencing a severe bleaching event and live in areas with annual mean open ocean seawater aragonite saturation above 3.3. Orange reefs are thermally stressed experiencing a severe bleaching event at least once every 10 years. Light blue reefs are chemically stressed (annual mean seawater aragonite saturation below 3.3), and reefs in red are both thermally and chemically stressed. Meissner et al (2012) Large-scale stress factors affecting coral reefs: open ocean sea surface temperature and surface seawater aragonite saturation over the next 400 years, Coral Reefs Ken Caldeira Senior Scientist, Carnegie Institution for Science: We have made projections* indicating that, if current CO2 emission trends continue, no coral reefs will be sustainable after about mid-century. That doesn’t mean they will all disappear at that time, but rather if they were subject to some kind of major disaster, they would be unlikely to be able to recover. The statement reads: “Scientists estimate 90 per cent of the world’s coral reefs will disappear in the next 35 years due to coral bleaching induced by global warming, pollution and over-development.” I am not familiar with every projection by every scientist, but it is not unlikely that some scientists have made such an estimate and it is possible that they could be right. It is also true that there would be scientists would would not think that that estimate was credible. The author of the article should have written: “Some scientists estimate … ” rather than “Scientists estimate … “. Assuming the scientists were correctly quoted, I would have been happier if they would have used the word “could” instead of “will” to express a sense of uncertainty. Things are bad enough. If there are greater than 10% of coral reefs hanging on in year 2052, they are likely to be unsustainable and on their way out. I don’t want to allow apologists for environmental destruction to be able to point to those reefs and claim that scientists in 2017 were being unnecessarily alarmist. Cao and Caldeira (2008) Atmospheric CO2 stabilization and ocean acidification, Geophysical Research Letters Ricke et al (2013) Risks to coral reefs from ocean carbonate chemistry changes in recent earth system model projections, Environmental Research Letters Silverman et al, (2009) Coral reefs may start dissolving when atmospheric CO2 doubles, Geophysical Research Letters Mark Eakin Scientist, Coordinator of NOAA’s Coral Reef Watch, National Oceanic and Atmospheric Administration: I rate this as accurate. While there is some variability among models and future greenhouse gas scenarios, the message from all of them is clear: we are likely to see near-annual bleaching, disease, and/or mortality on most of the world’s reefs by around mid-century. van Hooidonk et al (2016) Local-scale projections of coral reef futures and implications of the Paris Agreement, Scientific Reports van Hooidonk et al (2013) Temporary refugia for coral reefs in a warming world, Nature Climate Change Heron et al (2016) Warming Trends and Bleaching Stress of the World’s Coral Reefs 1985–2012, Scientific Reports Logan et al (2014) Incorporating adaptive responses into future projections of coral bleaching, Global Change Biology Maynard et al (2015) Projections of climate conditions that increase coral disease susceptibility and pathogen abundance and virulence, Nature Climate Change John Bruno Professor, The University of North Carolina at Chapel Hill: This statement is misleading. It should have said, ‘Unless we immediately and substantially curb greenhouse gas emissions, global coral loss will continue and most living coral will be gone by the end of the century.’ (Yet note we’ve already lost at least 50-75%, maybe even 90% of living coral.) There are plenty of dire predictions in the scientific literature on how ocean warming will impact coral reefs in coming decades. However, even the most pessimistic interpretations do not predict any reef will “disappear” in the next 35 years or even by the end of the century. Instead, what the science clearly indicates is that if we continue emitting greenhouse gases at our current rate, by mid-century tropical ocean temperatures in many regions will be high enough (1-2 C warmer than today) to cause regular (annual to semi-annual) bleaching events. But even after mass bleaching and mass coral mortality, the reef is still there. The coral skeletons that build up the reef don’t go anywhere in the near term. The best evidence for this interpretation is that it all already played out in the Caribbean (and inmany other regions). On the reefs I work on across the Caribbean, coral populations collapsed 30-40 years ago (from warming and disease) but all the reefs are physically still there. The loss of the corals is tragic and affects the functioning of the ecosystem, but still, Caribbean reefs lacking much coral can still be inhabited by a stunning diversity of fishes and invertebrates and staggering densities of animal life not seen in any other habitat on earth. They are still massively important for fisheries and tourism, despite the loss of most the coral. I suspect the writer wanted to keep things simple, but they greatly oversimplified the problem and the changes scientists expect to occur. We will likely continue to lose reef-building corals at a rate of 1-2% per year, but zero % of the world’s reefs are expected to disappear. It’s really a story of community change, rather than loss (not to downplay the importance of those changes). The science does suggest that ~ 10% of coral communities probably won’t be wiped out by warming this century. But that’s due to natural variation in warming rates and because some reefs in cooler regions will benefit from warming. https://www.sharethefacts.co/share/6fe0043b-aabf-400f-8074-8ee57b11f893"
https://science.feedback.org/review/scientists-just-detected-major-change-earths-oceans-linked-warming-climate-chris-mooney-the-washington-post/,2,"The Washington Post, by Chris Mooney, on 2017-02-15.",,"""Scientists have just detected a major change to the Earth’s oceans linked to a warming climate""",,,,,"This article in The Washington Post details a new study that compiled oxygen concentration measurements in the ocean from all over the world, showing a detectable global decrease of a little more than 2% since 1960. While the study does not definitively evaluate the cause of the observed decrease, this is an expected consequence of ocean warming. According to the scientists who reviewed the article, it accurately represents research on the topic—including clear and measured descriptions of the negative impacts of oxygen trends on marine life.See all the scientists’ annotations in context This is part of a series of reviews of 2017’s most popular climate stories on social media. REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Marina Levy CNRS Senior scientist, Université Pierre et Marie Curie: The content of the article is correct. It reports on a new study in Nature showing the first observational evidence of a diminution of oxygen levels in the oceans at a global scale. This is in agreement with projections from climate models. In some regions where oxygen concentrations are already low, this can be critical for ecosystems. Lauren Simkins Assistant Professor, University of Virginia: Changes in ocean chemistry, temperature, and circulation have significant consequences for marine life and can initiate positive feedbacks to accelerate ocean and atmosphere warming. This article is refreshing in that the author presents the results and significance of global ocean oxygen loss accurately and very clearly for non-expert audiences. Soeren Thomsen Postdoctoral Research fellow, Sorbonne University: This is a very good article which includes an interview with the first author as well as comments from two other researchers (Matthew Long and Denis Gilbert) who work on oxygen. The article is very accurate and the author does not exaggerate, but tries to explain several details. Jonathan Lauderdale Postdoctoral Research Associate, MIT: This article was well substantiated and measured in its reporting of the decline in global ocean oxygen concentrations, without being hysterical about the potential for mass fish suffocations, which I have seen in previous articles on this subject. Several quotes were from scientists not involved in the research paper, which lends credibility. Shame that the headline is not entirely transparent about the content of the article. The content does support the headline, but I would still consider this clickbait. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from the article; comments and replies are from the reviewers. 1.There has been a detectable decrease in oxygen concentrations in the ocean. This trend is projected to continue as the oceans warm. “A large research synthesis, published in one of the world’s most influential scientific journals, has detected a decline in the amount of dissolved oxygen in oceans around the world — a long-predicted result of climate change that could have severe consequences for marine organisms if it continues.” William Gilly Professor of Biology, Stanford University, Hopkins Marine Station: It has been clear for at least 10 years that oxygen has been declining in the world’s oceans, both in near-surface waters and at depth, particularly in those areas with strong, natural oxygen-minimum-zones. This new study greatly extends analyses of historical data to include a significantly longer time period, a much broader global area, and to the entire water column—from the surface to 6,000 meters [depth]. This volume represents most of the inhabitable volume of the planet, and what happens there impacts all organisms, including humans, that inhabit the thin skin of terra firma. “But as that upper layer warms up, the oxygen-rich waters are less likely to mix down into cooler layers of the ocean because the warm waters are less dense and do not sink as readily.” Emmanuel M Vincent Research Scientist, University of California, Merced: Enhanced stratification of the water column is indeed one mechanism that can explain the decrease in subsurface oxygen, notably in the tropics[1]. As the upper-layer of the ocean warms faster than the deeper layers, the temperature stratification increases, with the already-warm upper layer getting warmer. This enhanced thermal stratification acts as a barrier to vertical mixing, since warmer water is less dense (like when a low density fluid (e.g. oil) tops a high density fluid (e.g. water)). This stratification can prevent oxygen coming from the surface from reaching deeper layers where it gets depleted by biological activity (respiration). As climate change proceeds, the upper-ocean layer is also expected to become fresher (less salty) in the tropics as rainfall increase, further increasing the upper-ocean stratification[2]. [1] Behrenfeld et al (2006) Climate-driven trends in contemporary ocean productivity. Nature [2] Balaguru et al (2016) Global warming-induced upper-ocean freshening and the intensification of super typhoons. Nature Communications “‘Natural variations have obscured our ability to definitively detect this signal in observations,’ Long said in an email. ‘In this study, however, Schmidtko et al. synthesize all available observations to show a global-scale decline in oxygen that conforms to the patterns we expect from human-driven climate warming. They do not make a definitive attribution statement, but the data are consistent with and strongly suggestive of human-driven warming as a root cause of the oxygen decline.’” Soeren Thomsen Postdoctoral Research fellow, Sorbonne University: It’s very good that the difficulties in detecting the signal of declining oxygen are mentioned by citing a researcher. Also the very cautious statement on the reasons are good. No unnecessary panic mongering. Lauren Simkins Assistant Professor, University of Virginia: This is supported by the relatively rapid (sub-decadal to decadal) changes in global ocean oxygen loss that are consistent with rapid changes in atmospheric greenhouse gas emissions and associated warming effects on the atmosphere and ocean, when compared to the longer-term context recorded in geological archives of past ocean variability. “Because oxygen in the global ocean is not evenly distributed, the 2 percent overall decline means there is a much larger decline in some areas of the ocean than others.” Jonathan Lauderdale Postdoctoral Research Associate, MIT: I think this is a subtle and important point to make—2% globally might not seem that much but there will be areas where the decline is more significant, such as the boundaries of Oxygen Minimum Zones, where waters could go from habitable to uninhabitable. 2. Areas of the ocean that are extremely low in oxygen significantly impact local ecosystems. The trend of decreasing oxygen concentrations is associated with increasing consequences for marine life. “Moreover, the ocean already contains so-called oxygen minimum zones, generally found in the middle depths. The great fear is that their expansion upward, into habitats where fish and other organism thrive, will reduce the available habitat for marine organisms.” William Gilly Professor of Biology, Stanford University, Hopkins Marine Station: Expansion of naturally occurring oxygen-minimum-zones, particularly the world’s largest in the eastern Pacific Ocean, is becoming more and more firmly established over a vast region at depths of several hundred meters. What’s important—and counter-intuitive—about these oxygen-minimum-zone regions is that they tend to be dynamic features of some of the most productive upper-ocean areas on Earth. The Humboldt Current system off South America supports the world’s largest single-species fishery (Peruvian anchovetta) but has water with extremely low oxygen concentration in near-shore fishing zones at depths of less than 100 meters. Any vertical (upwards) expansion of this oxygen-minimum-zone will compress the surface layer where anchovetta as well as their predators (including human fishers) operate. Increasing the density of predator and prey in a shrinking volume seldom produces a pretty result. It’s not just a matter of reduced habitat for individual species—it’s more like putting an entire highly productive ecosystem into a trash compactor. “At the end of the current paper, the researchers are blunt about the consequences of a continuing loss of oceanic oxygen. ‘Far-reaching implications for marine ecosystems and fisheries can be expected,’ they write.” William Gilly Professor of Biology, Stanford University, Hopkins Marine Station: Potential biological consequences of the trends in ocean deoxygenation documented are, if anything, understated. This is really serious business. We have done a fair job at increasing public awareness of ocean acidification, and we need to do that with deoxygenation as well. The scary thing is we know very little how these two phenomena (low pH and low oxygen) work together to impact animals that live in the ocean—from plankton to predators. When you add increasing temperature to this mix, it is clear that we have a lot to learn. Soeren Thomsen Postdoctoral Research fellow, Sorbonne University: It’s true that this is the last sentence of the paper. However, they refer to another study here: Cheung et al (2012) Shrinking of fishes exacerbates impacts of global ocean changes on marine ecosystems. Nature Climate Change. 3. The warming of the world’s oceans also has many other impacts, including sea level rise and “positive feedbacks” that can further enhance global warming. “warmer oceans have also begun to destabilize glaciers in Greenland and Antarctica” Lauren Simkins Assistant Professor, University of Virginia: This is especially true for marine-terminating glaciers, meaning that the seaward-most margin of the glacier rests on a bed below sea level and, therefore, in direct contact with the ocean. Examples are glaciers in the Amundsen Sea, Antarctica such as Pine Island and Thwaites glaciers*, currently experiencing rapid retreat that is associated with warm ocean water melting the glaciers and their floating ice shelves. Jacobs et al (2011) Stronger ocean circulation and increased melting under Pine Island Glacier ice shelf. Nature Geoscience Shepherd et al (2004) Warm ocean is eroding West Antarctic ice sheet. Geophysical Research Letters “On top of all of that, declining ocean oxygen can also worsen global warming in a feedback loop. In or near low oxygen areas of the oceans, microorganisms tend to produce nitrous oxide, a greenhouse gas, Gilbert writes.” Emmanuel M Vincent Research Scientist, University of California, Merced: Another “positive feedback loop” related to ocean warming and increased stratification is that this can reduce the ocean CO2 uptake, by preventing CO2 from being mixed down into the deep ocean layers. Matebr and Hirst (1999) Climate change feedback on the future oceanic CO2 uptake. Tellus"
https://science.feedback.org/review/california-dam-crisis-says-changing-climate-noah-diffenbaugh-new-york-times/,1,"The New York Times, by Noah Diffenbaugh, on 2017-02-14.",,"""What California’s Dam Crisis Says About the Changing Climate""",,,,,"This op-ed in the New York Times written by Stanford researcher Noah Diffenbaugh discusses northern California’s Oroville Dam, where damage to a spillway recently led to a temporary evacuation. Scientists who reviewed the article found that its description of the stress that climate change exerts on water infrastructure in the American West—both flood protection and water supply management during drought—is mostly accurate. However, the article’s title, “What California’s Dam Crisis Says About the Changing Climate”, can be read to imply that climate change, rather than a structural failure, is primarily responsible for the current situation at the Oroville Dam—which is not what the content of the article suggests.REVIEWERS’ OVERALL FEEDBACK: Roger Bales Professor of Engineering, University of California, Merced: Factual & background statements do generally reflect common knowledge. Climate warming means that we do need to add resiliency to our infrastructure. The 4 recommendations of the article are on track, and consistent with the state’s Water Action Plan. Upmanu Lall Professor of Engineering, Columbia University: Misleading title—the dam crisis is primarily about the aging infrastructure and the neglect of investment in engineering and R&D as to how to plan, design, and build a new generation of water and energy infrastructure, while maintaining what we have. It tells us nothing about climate change. The article itself is more nuanced and balanced, but ends up being an organ for the climate change story, which is important, while mentioning the need for urgent investment in and action on primary infrastructure only in passing. Ben Henley Postdoctoral research fellow, University of Melbourne: This is an eloquent and thoughtful article and is based on sound science in my opinion. The author’s down-to-earth descriptions of our understanding of the physical mechanisms are well communicated. He has linked his claims to peer-reviewed science in high-ranking journals. He has carefully linked the recent events to a number of broad-brush insights for the benefit of society. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Takeaways: 1. Warm dry years followed by extremely wet years have always been part of the climate of California, but warming can worsen both extremes by increasing evaporation, which makes droughts worse as well as put more moisture into the atmosphere allowing heavier downpours. The juxtaposition of five years of hot, dry conditions followed by more rain than reservoirs can store may seem incongruous. However, this is exactly what climate scientists have predicted for California since at least the 1980s: protracted periods of warm, dry conditions punctuated by intense wet spells, with more rain and less snow, causing both drought and floods. Roger Bales Professor of Engineering, University of California, Merced: Point that “… hot, dry conditions followed by more rain than reservoirs can store ..” is not “incongruous”, but rather consistent with the climate history of California. “[…] in fact this pattern is already emerging, with the conditions that create extremely warm dry years and extremely wet years both becoming more frequent.” This statement is supported by the study hyperlinked in the text*, which identified an increase in regional atmospheric circulation patterns associated with both extremely wet and extremely dry years in California since the middle of the 20th century. Swain et al (2016) Trends in atmospheric patterns conducive to seasonal precipitation and temperature extremes in California, Science 2. Warming means that a growing fraction of precipitation falls in the form of rain rather than snow, which increases runoff. “In an old climate, … extremely warm years were less common and snowpack was more reliable … With the shift toward more rain rather than snow, and the earlier melting of the snowpack, water managers need to release water more frequently for flood control.” This statement is supported by a recent study* of the amplified warming rate experienced at high altitudes in the Sierra Nevada, which results from the loss of sunlight-reflecting snow cover. Walton et al (date) Incorporating Snow Albedo Feedback into Downscaled Temperature and Snow Cover Projections for California’s Sierra Nevada, Journal of Climate Roger Bales Professor of Engineering, University of California, Merced: It doesn’t take much warming to change snowstorms into rainstorms. With a warmer climate, we get these winter storms, which dump rain rather than snow. The “need to release water more frequently” is not necessarily true. The key needs are to upgrade the spillway, damage to which is limiting release capacity, and update the information system used to decide releases. The state is well aware of this, and public funds for investments remain limited in the current political climate."
https://science.feedback.org/review/big-melt-global-sea-ice-record-low-usa-today-doyle-rice/,1.4,"USA Today, by Doyle Rice, on 2017-02-08.",,"""The big melt: Global sea ice at record low""",,,,,"This USA Today article by Doyle Rice describes a US National Snow & Ice Data Center announcement that the combined extent of Arctic and Antarctic sea ice set a record low for January extent. The five scientists who reviewed the article concluded that it is accurate. It properly conveys the core facts about global sea ice extent and the attribution of continuing sea ice loss to human-induced warming of the climate—primarily in the Arctic, as the low sea ice extent around Antarctica this year has not yet been clearly connected to climate change.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Steffen Tietsche Senior Scientist, European Centre for Medium-Range Weather Forecasts: The article does a good job in conveying the basic facts about sea ice and how it has been changing to a reader without prior knowledge of the subject. The strong statements it makes about the recently observed sea ice extremes are correct, and backed up by appropriate numbers, figures, and expert quotations and references. Michel Tsamados Lecturer (Assistant Professor), University College London: This is a factual article and gives an accurate representation of the state of the sea ice cover in 2016/2017. One small caveat is that the author states that “sea ice is shrinking to levels not seen in thousands of years” which is a bit vague and still a topic of active research. The IPCC report has a more timid statement (maybe too cautious?). This article is based on facts, and does not attempt to over-interpret or extrapolate from these facts. References: to the sources are provided. I consider the article trustworthy. Alek Petty Postdoctoral associate, NASA Goddard Space Flight Center: The article did a pretty good job in general of discussing recent sea ice decline, relying mainly on information from the NSIDC and NASA (reliable sources). The article was sometimes a bit loose in the language used, however (as highlighted by the annotations). This was somewhat unfortunate, as it would have been a good opportunity to provide the reader with more insight into the impact of sea ice decline, and the open questions that remain (e.g. regarding how it might impact US weather). Twila Moon Research Scientist, University of Colorado, Boulder: An excellent article that does a good job of summarizing current measurements of the loss of sea ice, especially in the Arctic. The article also hits on why this change is important and that the reduction in sea ice is directly connected to man-made climate change. These are important scientific points. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : 1.Global sea ice extent is at an all time low. “There is now less sea ice on Earth than at any time on record. Ice in the Arctic and Antarctic melted to record low levels in January, scientists reported this week.” Michel Tsamados Lecturer (Assistant Professor), University College London: Focusing on sea ice extent can be dangerous as it is partly driven by short-term weather patterns, in contrast to the volume of sea ice that is now regularly monitored by European Space Agency satellite Cryosat and is more indicative of slower climatic changes. Having said that, 2016/2017 has displayed such unusual patterns in total sea ice extent that it has triggered renewed interest in the scientific community. One has to bear in mind that the seasonal developments of Arctic and Antarctic sea ice are out of phase by ~6 months. Hence, the Earth’s “total” sea ice extent is a number with limited meaning, and is not directly obvious to interpret. In addition, this number smooths out regional variations, which can be particularly pronounced in the Antarctic. Nevertheless, just like global-mean temperature or the GDP of a country, this number can be useful to have a 0th-order view on the health and state of our planet. “Using paleoclimatic data, studies suggest sea ice is shrinking to levels not seen in thousands of years.” Michel Tsamados Lecturer (Assistant Professor), University College London: The relevant assessment from the latest IPCC report(Chapter 5 Information from Paleoclimate Archives) is: “There is medium confidence from reconstructions that the current (1980–2012) summer sea ice retreat was unprecedented and sea surface temperatures in the Arctic were anomalously high in the perspective of at least the last 1450 years. Lower than late 20th century summer Arctic sea ice cover is reconstructed and simulated for the period between 8000 and 6500 years ago in response to orbital forcing.” 2.The pronounced loss of sea ice in the Arctic is largely due to human-caused climate change, but natural variability can also be considerable—especially in the Antarctic. “‘Greenhouse gases emitted through human activities and the resulting increase in global mean temperatures are the most likely underlying cause of the sea ice decline,’ the snow and ice data center said.” Observed trends in Arctic sea ice result from the superposition of forced, man-made variations and internally generated variations. While it is clear from the literature (see IPCC WG1 AR5 Chapter 10 for a review) that observed trends cannot be explained by internal variability alone, it should be remembered that internal variability can also modulate the forced trends, in a way that is complex to properly describe. In conclusion, greenhouse gases are well responsible for the observed decline, but their effect on sea ice trends may have even been amplified by internal variability. “The amount of summer sea ice in the Arctic has steadily declined over the past few decades because of man-made global warming, according to the National Oceanic and Atmospheric Administration.” Michel Tsamados Lecturer (Assistant Professor), University College London: A recent study* makes this link very tangible by attributing every loss of 3 ± 0.3 m2 of September sea-ice area to 1 metric ton of man-made CO2 emissions. Notz and Stroeve (2016) Observed Arctic sea-ice loss directly follows anthropogenic CO2 emission, Science “Sea ice thickness also substantially declined in the latter half of the 20th century, the snow and ice data center said.” Twila Moon Research Scientist, University of Colorado, Boulder: This is an important change to emphasize because sea ice thickness is also an indicator of sea ice age. While thin sea ice can reform more quickly year to year, thick sea ice requires more time. The loss of thick sea ice is perhaps even more striking than the loss of ice area. It should be added here that this is talking about Arctic sea ice. Alek Petty Postdoctoral associate, NASA Goddard Space Flight Center: Agree—and adding how we don’t know much about Antarctic sea ice thickness would have been helpful. “At the bottom of the world, sea ice is also at all-time record low levels around Antarctica, the data center said. The lack of ice in the Antarctic, where it is currently summer, is most pronounced in the Amundsen Sea, where only a few scattered patches of ice remain.” Looking at recent time-evolution of Antarctic sea ice anomalies since November 2016 is insightful to appreciate the complexity of Antarctic sea ice dynamics. In early austral spring (below) the total Antarctic sea ice extent was already anomalously low because of strong ice retreat in the Indian Sector. Three months later, the extent anomaly has persisted but is due to an unusual ice retreat in the Amundsen sector—i.e., at the exact opposite location—as the article correctly reports: This short example reveals why sea ice extent is a useful, but not sufficient diagnostic to characterize the recent sea ice variability. “Antarctic ice fluctuates wildly year to year, and the link to man-made global warming there is not clear, NASA ice expert Walt Meier said.” Michel Tsamados Lecturer (Assistant Professor), University College London: This is true for the Antarctic, while the Arctic is expected to respond more significantly to climate change—the so-called polar amplification. This is described in detail in Box 5.1 | Polar Amplification of IPCC chapter 5 Information from Paleoclimate Archives. On short time scales (~100 years) the Antarctic response differs from the Arctic and displays a delayed warming. There are several hypotheses proposed (see, for example, Ferreira et al, 2016*). Ferreira et al (2016) Antarctic Ocean and Sea Ice Response to Ozone Depletion: A Two-Time-Scale Problem, Journal of Climate 3.Sea ice loss can influence climate and weather patterns beyond just the polar regions, but some aspects of these connections are still uncertain. “[Sea ice] also helps regulate the planet’s temperature by influencing the circulation of the atmosphere and ocean. It can affect weather in the U.S.” Michel Tsamados Lecturer (Assistant Professor), University College London: Sea ice acts as an insulating blanket over the Arctic Ocean and by removing it (via our impact on the climate) we are “performing the largest experiment in oceanography”, allowing the winds and atmosphere to directly interact with the Arctic Ocean and therefore potentially waking up the “sleeping Arctic Ocean” both mechanically and thermodynamically. (See the Lunch Hour Lecture at University College London below.) Twila Moon Research Scientist, University of Colorado, Boulder: Sea ice cover is also better at reflecting energy from the sun than open ocean. This makes sea ice an important player in keeping the ocean surface from taking up additional heat. There is currently no consensus in the scientific community about the magnitude of Arctic-lower-latitudes teleconnections compared to other teleconnections (e.g. from the tropics). This statement has to be taken with caution."
https://science.feedback.org/review/daily-mail-inflates-disagreement-scientists-data-handling-make-unsupported-accusation-data-manipulation/,Unsupported,"Daily Mail, David Rose, 2017-02-04",world leaders were duped into investing billions over manipulated global warming data,,Unsupported: David Rose does not provide tangible evidence of “data manipulation”. The claim that the data discussed were critical to world leaders signing the Paris agreement is also not supported by evidence.,"David Rose provides no evidence that global temperature data were manipulated. In reality, the data in question 1) have been verified by independent research and 2) do not significantly change the assessment of global warming relied on by policymakers.","How world leaders were duped into investing billions over manipulated global warming data… The report claimed the pause in global warming never existed, but it was based on misleading, ‘unverified’ data",,"Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: The “astonishing evidence” that David Rose purports to reveal in no way changes our understanding of modern warming or our best estimates of recent rates of warming. It does not in any way change the evidence that policymakers have at their disposal when deciding how to address the threats posed by climate change. If anything, there is strong independent evidence that NOAA’s new record may be the most accurate one over the last two decades, at least for the two-thirds of the world covered in ocean. Rose’s claim that NOAA’s results “can never be verified” is patently incorrect, as we just published a paper independently verifying the most important part of NOAA’s results. I recently led a team of researchers that evaluated NOAA’s updates to their ocean temperature record. In a paper* published last month in the journal Science Advances, we compared the old NOAA record and the new NOAA record to independent instrumentally homogenous records created from buoys, satellite radiometers, and Argo floats. Our results, as you can see in the chart below, show that the new NOAA record agrees quite well with all of these, while the old NOAA record shows much less warming. The new NOAA temperature record is by no means an outlier when compared to other groups producing global (land and ocean) surface temperature records. It shows less warming in recent years than records from Berkeley Earth, NASA, and Cowtan and Way, and a bit more warming than found in the Hadley Centre/CRU record. The old NOAA record, on the other hand, was on the bottom of the pack, with less warming than found by the other groups. Figure: Global land/ocean temperature records from NOAA, NASA, Berkeley Earth, Hadley/UAE, and Cowtan and Way. Note that the old (pre-Karl et al.) NOAA temperature record is only available through the end of 2014. Hausfather et al (2017) Assessing recent warming using instrumentally homogeneous sea surface temperature records, Science Advances Timothy Osborn Professor, University of East Anglia, and Director of Research, Climatic Research Unit: My overall take on the article is that it is misleading and inaccurate. The headline’s claim that the Karl et al. paper “duped” world leaders into investing billions is utterly false. Leaving aside the question of whether the Karl et al. paper is invalid (it isn’t), the improvement to global temperature records reported by Karl et al. had only a small impact* on our estimate of global warming over the last century or more. It is this warming over the last 50 to 150 years that is most relevant for assessing the influence of greenhouse gases and particularly our emissions of CO2. These long-term warming trends (hardly affected by the Karl et al. paper) demonstrate the warming induced by CO2 and other greenhouse gases and provide (part of) the scientific basis for international climate agreements, like the one agreed by world leaders in Paris in 2015. *A quote from Karl et al. (2015) supports this: “For the full period of record (1880–present) (Fig. 2), the new global analysis has essentially the same rate of warming as that of the previous analysis (0.068°C/decade and 0.065°C/decade, respectively)”. Peter Thorne Professor, Maynooth University: Would Karl et al not having appeared make any material difference to our understanding of climate change? No. We have multiple indicators of a warming world (see e.g. IPCC WG1 AR5 FAQ 2.1). Also, Karl et al. sits nicely within the range of available surface temperature estimates, which includes several independent analyses and several dynamical reanalysis products. Removing the estimate wouldn’t even modify the range of available estimates to the community. So, on several grounds it’s not as important as it’s made out to be by those wishing to discredit it. That’s not to say it wasn’t important. Just that whether it existed or not wouldn’t make a difference to the biggest picture. Victor Venema Scientist, University of Bonn, Germany: Since the 19th century we have seen about 1 °C (1.8 °F) of warming. The adjustments of Karl and colleagues (2015) are only of a few hundredths of a degree Celsius and thus do not appreciably change the scientific estimates of the climate sensitivity. The largest adjustment is actually making past sea surface temperatures warmer because old bucket measurements have a known cool bias (which actually reduces the magnitude of the warming trend). That adjustment is important for the assessment of climate sensitivity using only instrumental data. In the figure below, the thick black line shows the new assessment (ERSST.v4) and the thin red line the previously estimated global temperature signal (ERSST.v3). Differences are mostly less than 0.05°C, both warmer and cooler. The [exaggeration] is the minute change at the right end of the curves. Source: Karl et al. (2015)"
https://science.feedback.org/review/global-surface-temperatures-increasing-according-climate-projections-contrary-wall-street-journal-claim/,Misleading,"The Wall Street Journal, Wall Street Journal editorial, 2017-01-19",the warming is not nearly as great as the climate change computer models have predicted.,,"Fails to grasp significance of observation: This claim is used to support an argument that climate models failed to forecast global surface temperature warming, but cherry-picks a period of time too short to provide a meaningful comparison. ",Global surface temperatures are increasing consistent with the long-term trend projected by climate models.,the warming is not nearly as great as the climate change computer models have predicted. […]U.N. Intergovernmental Panel on Climate Change simulations forecast surface temperatures to increase on average 0.2 degrees Celsius per decade in the early 21st century. The warming over the first 15 years was closer to 0.05 degrees Celsius.,,"Christopher Merchant Professor, University of Reading and UK National Centre for Earth Observation: Although climate modellers tend to quote the trend to warmer temperatures in units of “degrees per decade”, it is a misunderstanding to interpret that to mean that they expect every decade to have that trend. This is why in the quoted statement, the forecast is for increases to be “on average” 0.2 °C. Just as weather fluctuates from day to day, there are fluctuations between years and decades, too. Piers Forster Professor, University of Leeds: The high emissions scenario (RCP8.5) model simulations did show around 0.2 °C warming per decade. But the IPCC report (Chapter 11, WG1, AR5, Fig 11.25) never relied on just these runs to make its prediction. It relied on multiple lines of evidence. Its temperature prediction was in fact around 0.05 to 0.15 C per decade. The statement “the warming over the first 15 years is 0.05 °C per decade” is not correct. (This was probably meant to be degrees per decade from an old version of the HadCRUT dataset with limited coverage on the Arctic). The latest analysis and synthesis of the different records published in Science in January* constrains sea-surface temperatures trends over the last 19 years to between 0.07 and 0.12 °C per decade. Global temperatures have been rising slightly faster than this due to land surface warming more. Hausfather et al (2017) Assessing recent warming using instrumentally homogeneous sea surface temperature records, Science Advances Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: Since the start of the 21st century, climate models predict 0.2 °C per decade surface warming. Observed surface warming over that same period has been 0.2 °C (NASA), 0.19 °C (NOAA) 0.18 °C (Berkeley/ Cowtan and Way), and 0.16 °C (Hadley). All of these are statistically indifferentiable from model projections over this period. In general, recent temperatures have been pretty close to the multi-model mean: Model comparisons with satellite data are more difficult as satellites don’t measure the Earth’s surface temperature. Some satellite records (RSSv4, UAHv5.6) are in reasonable agreement with model projections for tropospheric temperatures between 2000 and present, while others (UAHv6 beta, RSSv3) are notably cooler. Shaun Lovejoy Professor, McGill University: The figure below from Lovejoy (2015)* gives some details, but the basic claim of 0.2 °C too high is essentially correct. However, as the figure shows, the temperature was accurately forecast (actually hindcast) to within 0.05 °C by using a stochastic (not General Circulation Model) modelling approach. The stochastic approach worked well because the so-called pause (since 1998) was actually simply a return to the long-term (anthropogenically forced) trend that followed the massive pre-pause warming from 1992 to1998. The key point is that the fact that General Circulation Model’s tended to over-forecast the warming is a model and/or data problem (there are many different explanations in the literature), but this in no way alters the fact that the temperatures are almost exactly varying about the long term anthropogenic trend as expected. Lovejoy (2015) Using scaling for macroweather forecasting including the pause, Geophysical Research Letters"
https://science.feedback.org/review/scientists-officially-declare-2016-hottest-year-record-chris-mooney-the-washington-post/,1.9,"The Washington Post, by Chris Mooney, on 2017-01-18.",,"""U.S. scientists officially declare 2016 the hottest year on record. That makes three in a row.""",,,,,"On January 18th, NOAA and NASA released their annual assessment of the state of the global climate, including the fact that 2016 was the warmest year on record. The Washington Post article discusses the degree of confidence in this result, the factors contributing to the new record, and some of the ways in which different regions were impacted by this warmth. Scientists found this article accurate and insightful in that it provides the context necessary to understand the significance of this new temperature record. It correctly notes that the record can be tied to human influence on the climate, even though El Niño played a role in further boosting the global temperature.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. James Screen Associate Professor, University of Exeter: The article accurately conveys the US agencies’ declaration of 2016 as the hottest year on record. It provides some good background material on why the agencies’ numbers differ slightly (treatment of the Arctic) and the contributing roles of El Niño and man-made global warming. Mark Eakin Scientist, Coordinator of NOAA’s Coral Reef Watch, National Oceanic and Atmospheric Administration: The article accurately depicted the new data released by NOAA and NASA and used appropriate and valid scientific quotes to place the news in context. It also went beyond the simple temperature analysis to discuss some of the significant impacts felt in various parts of the world this year. Daniel Swain Climate Scientist, University of California, Los Angeles: This piece accurately describes the facts and broader context of record-breaking global warmth in 2016. Christopher Colose Research Scientist, SciSpace LLC, NASA Goddard Institute for Space Studies: This is a useful summary of the key points outlined by NASA and NOAA, discussing the proximate causes of the 2016 warmth compared to surrounding years (mostly El Niño), and also that there is a sharp upward trend upon which natural variability is superimposed. Andrew King Research fellow, University of Melbourne: This article accurately describes why 2016 was record-breaking and makes insightful comments about the causes for differences between datasets. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: An excellent overview of 2016 temperatures, with some detailed exploration of the differences between NOAA and NASA records. The only thing I might have added is some discussion of satellite tropospheric temperatures. James Renwick Professor, Victoria University of Wellington: An excellent summary, drawing on several leaders in the field of climate science. Julien Emile-Geay Assistant Professor, University of Southern California: Chris Mooney reads what scientists say and reports on it without hyperbole or distortion. Thermometers and sea ice have no political agenda, and this article does a good job of summarizing the most recent evidence and scientific analyses based on them. Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: Balanced descriptions of different datasets, and used explanations from scientists in appropriate places very well. Victor Venema Scientist, University of Bonn, Germany: Great article, accurate in detail (the reasons for fluctuations and for differences between datasets) while keeping sight of the big picture (the long-term trend due to man-made global warming). Aimée Slangen Researcher, Royal Netherlands Institute for Sea Research (NIOZ): The article provides a good evaluation of the record year 2016 by including data from different datasets and agencies. It not only discusses the global mean temperature record, but also notable events such as the Arctic sea ice low. All of this combined, it shows that the big picture is clearer than ever. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from the article; comments and replies are from the reviewers. 1.2016 was the warmest year on record in all agencies’ datasets. The small differences between datasets mostly relate to their methods of accounting for warming in the Arctic, where measurements are limited. “NASA concurred with NOAA, also declaring 2016 the warmest year on record in its own data set that tracks the temperatures at the surface of the planet’s land and oceans, and expressing ‘greater than 95 percent certainty’ in that conclusion. (In contrast, NOAA gave a 62 percent confidence in the broken record.)” Victor Venema Scientist, University of Bonn, Germany: The difference between NOAA and NASA-GISS is because of the way the Arctic—where much of the warming was in 2016, but where we do not have many measurements—is treated. NOAA excludes much of the Arctic, which gives it a cool bias in 2016, which is accounted for by a larger uncertainty. NOAA. The gray areas are where NOAA’s methods do not have enough observations to compute the temperature. Not computing a temperature is similar to assuming these regions warm like the global average, but the Arctic warmed more. GISTEMP of NASA-GISS uses other mathematical methods and does compute temperatures for the Arctic, which results in a more accurate global average. “Two other global agencies, the Japan Meteorological Agency and Britain’s Hadley Center, also track global temperatures.” Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: Other groups, including Berkeley Earth and Cowtan and Way, also agree that 2016 was a record warm year. It’s also a record warm year when you look at raw ocean and land data with no corrections or adjustments. “But the differences between NOAA and NASA aren’t that significant, Schmidt further argued, in the context of the bigger picture. ‘Getting hung up on the exact nature of the records is interesting, and there’s lots of technical work that can be done there, but the main take-home response there is that the trends we’ve been seeing since the 1970s are continuing and have not paused in any way,’ he said.” Daniel Swain Climate Scientist, University of California, Los Angeles: This section accurately portrays the overall context of the 2016 record, and the fact that the modest differences between datasets do not change the “big picture” conclusion that the Earth is warming and that 2016 was an extraordinary year even in that context. 2.This record is mostly attributable to human-induced global warming, but the El Niño event in 2016 also contributed. “[Jonathan Overpeck:] ‘No doubt about it anymore — humans, mainly by burning fossil fuels, are cooking the planet,’ Overpeck said.” Aimée Slangen Researcher, Royal Netherlands Institute for Sea Research (NIOZ): There is indeed a vast body of literature on ”detection and attribution” showing how the increase of greenhouse gases can be linked to changes in the climate system. Already in the most recent IPCC report this was shown for quantities such as surface temperature, ocean temperature, global mean sea level rise, Arctic sea ice loss, and glacier and ice sheet mass loss. Publications since have confirmed these findings. “[Jonathan Overpeck:] ‘it is caused by humans’” Margot Saher Lecturer, Bangor University, Wales, UK: The usual method of prying apart the various factors responsible for temperature changes is by modelling; we know the input of the Sun, we know the composition of the atmosphere, etc. If you have a climate model that, with these parameters, can reproduce the climate of the past, you can be fairly sure that, even being by definition a simplification, it gets the physics right. You can then use the model to calculate what the influence of each individual parameter was*. You can even switch parameters on and off to see what happens. These models can then also be used for climate predictions under various assumptions on, say, greenhouse gas emissions. Huber and Knutti (2012) Anthropogenic and natural warming inferred from changes in Earth’s energy balance, Nature Geoscience “‘This El Niño might have contributed about a quarter or a third’ of the record in 2016, said Deke Arndt, chief of the global monitoring branch at NOAA’s National Centers for Environmental Information, on a press call Wednesday.” Christopher Colose Research Scientist, SciSpace LLC, NASA Goddard Institute for Space Studies: I find this part confusing. The “percentage of the anomaly” caused by El Niño depends of course on the anomaly, which depends on the baseline. So it’s not really a useful number. El Niño caused a much larger fraction if you only look at a very recent baseline (e.g. just compare to 2014-15). A more straightforward number is the 2016 anomaly relative to what it would have been if ENSO were in a neutral phase. I calculated this to be ~0.13 C (0.23 F). Victor Venema Scientist, University of Bonn, Germany: I agree with Chris Colose. If you mention a fraction (a quarter or a third) you need to mention relative to what. The total warming since 1900 is about 1°C. The influence of El Nino on the 2016 temperature was small compared to that. Source “The particular signature of warming in 2016 was also revealing in another way, Overpeck said, noting that the stratosphere… saw record cold temperatures last year” Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: The troposphere (the lower part of the atmosphere) has also been rapidly warming. A newly updated record from Remote Sensing Systems using data from NASA satellites shows more warming in the troposphere than on the surface since 1979 (when satellite records began): “[Gavin Schmidt:] ‘We don’t expect record years every year, but the ongoing long-term warming trend is clear.’” Andrew King Research fellow, University of Melbourne: This is a really important point, especially as 2017 is likely to not break the 2016 record. We expect year-to-year variability, so we may not break the 2016 record for a few years, but the overall trend is upwards. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: Scientists like NASA’s Gavin Schmidt are also predicting slightly cooler 2017 temperatures as the El Niño fades, with 2017 projected to be somewhere between the 2nd and 5th warmest year on record. That said, we wouldn’t expect every single year to be a new record, and a slightly cooler 2017 is in no way inconsistent with the long term warming trend. 3.The consequences of ongoing climate change include impacts on coral reefs, Arctic sea ice coverage, and wildfires, among other things. “Last year’s warmth was manifested across the planet, from the warm tropical ocean waters off the coast of northeastern Australia, where the Great Barrier Reef experienced its worst coral bleaching event on record and large scale coral death, to the Arctic, where sea ice hit regular monthly record lows and overall temperatures were also the warmest on record, at least from January through September 2016.” Daniel Swain Climate Scientist, University of California, Los Angeles: This section accurately describes major 2016 events that occurred in the Earth system, and which most likely would not have occurred without global warming. Mark Eakin Scientist, Coordinator of NOAA’s Coral Reef Watch, National Oceanic and Atmospheric Administration: The article overlooks the fact that not only was the bleaching on the northern Great Barrier Reef the worst on record, so was the bleaching in many areas around the world. In fact, the global coral bleaching event that is still underway is the longest, most widespread, and perhaps most damaging event on record. “Extreme high temperatures were seen from India — where the city of Phalodi recorded temperatures of 51 degrees Celsius (123.8 Fahrenheit) in May, a new national record — to Iran, where a temperature of 53 degrees Celsius (127.4 F) was recorded in Delhoran on July 22.” Andrew King Research fellow, University of Melbourne: No direct link with climate change has been drawn by the article here and this is good. For these daily heat records, attribution to human-caused climate change is a lot harder than for extremes that occur on longer or larger scales. Indeed, in parts of India, the increase in aerosols due to pollution has counteracted the warming from greenhouse gas emissions so that there is virtually no trend in extreme high temperatures."
https://science.feedback.org/review/ocean-acidification-yet-another-wobbly-pillar-climate-alarmism-james-delingpole-the-spectator/,-2,"The Spectator, by James Delingpole, on 2016-04-30.",,"""Ocean acidification: yet another wobbly pillar climate alarmism""",,,,,"Research shows that the pH of the ocean is currently decreasing due to human emissions of CO2 and that this already has negative consequences for marine ecosystems—and continued emissions is expected to have further negative consequences. The article in The Spectator claims the contrary. The scientists who have analyzed the article show that it contains significant inaccuracies, notably for its core assumptions, and misrepresents scientific studies and scientists it cites to make its point. Reviewers also note that the article knocks down strawman arguments that do not represent the state of scientific knowledge (scientists do not claim the ocean will become a “giant acid bath”) and uses derogatory language by referring to ocean acidification researchers as “alarmists”. Note: This article, published in April 2016, is being assessed now because of renewed interest in the media following IPSO’s ruling (IPSO is the UK Independent Press Standards Organisation).See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Howard Browman Principal Research Scientist, Norwegian Institute of Marine Research: As Phil Williamson has carefully documented, it is a story built upon selective back-grounding, based upon dubious sources, and presented in support of the author’s own predetermined storyline and conclusion. Adam Subhas PhD candidate, Caltech: This article bases its arguments on non-peer-reviewed publications and a study which uses poorly calibrated historical data. The article also oversimplifies the science behind ocean acidification in an attempt to trivialize well-understood chemical principles that predict how CO2 dissolving into the ocean will affect ocean pH. Ken Caldeira Senior Scientist, Carnegie Institution for Science: The chemistry of ocean acidification is well understood. Negative biological consequences have been documented for many marine organisms in a diverse set of carefully controlled experiments. I was involved in an experiment in Australia’s Great Barrier Reef where we added an ‘antacid’ to a plume of seawater, bringing seawater chemistry closer to what it was several hundred years ago. We let that water flow over a patch of reef and measured an increase in the growth rate of the reef. This showed that the increase in acidity caused by our CO2 emissions is already slowing reef growth, harming the reef. Our measurements come out of sophisticated and carefully calibrated scientific instruments. They measure what is out there in the physical world, without any reference to our political views or our degree of alarm. Our measurements are not a matter of opinion. Jean-Pierre Gattuso Research Professor, CNRS, Université Pierre et Marie Curie and IDDRI: This is an appalling article which distorts the scientific evidence by disqualifying thousands of peer-reviewed articles and highlighting only two un-peer-reviewed publications from non-expert authors. Tullio Rossi Marine biologist, University of Adelaide: This is by far the most inaccurate article on ocean acidification I have ever seen. It is an explosive mix of false statements, cherry picking, and plain anti-science feelings. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from the article; comments and replies are from the reviewers. 1. The acidity of seawater (hydrogen ion concentration) has increased by about 30% over the industrial era due to the human-caused increase of atmospheric CO2. “In 2004, two NOAA scientists, Richard Feely and Christopher Sabine, produced a chart showing a strong correlation between rising atmospheric CO2 levels and falling oceanic pH levels. But then, just over a year ago, Mike Wallace, a hydrologist with 30 years’ experience, noticed while researching his PhD that they had omitted some key information[…] his results were surprising: there has been no reduction in oceanic pH levels in the last -century.” Tullio Rossi Marine biologist, University of Adelaide: This is plain wrong. Oceanic pH levels decreased by 0.1 units compared to pre-industrial levels. This corresponds to a 30% increase in acidity. For a primer on pH, see this NOAA explainer. Peer-reviewed references: Doney et al (2009) Ocean acidification: the other CO2 problem, Annual Review of Marine Science Raven et al (2005) Ocean acidification due to increasing atmospheric carbon dioxide, The Royal Society Ken Caldeira Senior Scientist, Carnegie Institution for Science: This statement just flies in both the face of observational facts and a basic understanding of chemistry. I would love to hear a cogent explanation of how atmospheric CO2 levels could rise over the course of a century without producing a decrease in ocean pH. Observations near Hawaii and several other open ocean environments show clear decreasing trends in ocean pH. See, for example this report from the European Environment Agency. It is one thing to challenge future projections, but rejecting well-established scientific facts is another thing entirely. Figure: Decline in pH measured at the Aloha station as part of the Hawaii Ocean time-series. Source Richard Feely Senior Scientist, NOAA's Pacific Marine Environmental Laboratory: Michael Wallace contacted Chris Sabine and myself several years ago and asked how to get access to historical pH measurements in the oceans so he could determine long-term trends of global ocean pH for himself. We directed him to both modern (as published in Feely et al., 2008) and historical pH measurements archived at the NOAA National Centers for Environmental Information. We cautioned him that the earlier data sets prior to 1989 had significant issues with data quality as described in the document that went along with the data set obtained from NCEI. Mr. Wallace went on to perform his analysis of the historical data without regard for the oceanographic community’s concerns about the data quality or for the proper methodology to perform this kind of analysis. He chose to publish his results within the context of an interview written by Marita Noon in the Farmington Daily Times. We responded by correcting the record by formally restating our concerns about Mr. Wallace’s incorrect use of the historical data on our website. In short, Wallace’s chart does not show any kind of useful trend in global ocean pH because the data he used, and the way he used them, were not appropriate for this kind of analysis. In the first place, the pH measurements prior to 1989 were not reliable enough to detect small pH changes over that period. In addition, companion meta data on sensor calibration, pH scales, and temperature corrections were not available. Finally, the data were so limited that no meaningful global averages could be determined. The article by Mr. Delingpole in The Spectator failed to address these important issues, as Philip Williamson correctly points out in his response to the article. “Ocean acidification is the terrifying threat whereby all that man-made CO2 we’ve been pumping into the atmosphere may react with the sea to form a sort of giant acid bath.” Jean-Pierre Gattuso Research Professor, CNRS, Université Pierre et Marie Curie and IDDRI: That is incorrect. No peer-reviewed article claim that the ocean will become acid (pH < 7). “‘Acid’ was chosen, Moore believes, because it has ‘strong negative connotations for most people’.” Tullio Rossi Marine biologist, University of Adelaide: The terms acidification was not chosen for its negative connotation but rather because it defines the direction of change. Here is a simple example: when you describe the cooling of your coffee what term do you use? Cooling or un-warming? If the temperature is going down we say it is cooling. If the temperature is going up we say it is warming. The same applies to acidity. When the pH of something goes down we say that it is acidifying. That simple. “so more correctly it should be stated that the seas are becoming slightly less alkaline.” Adam Subhas PhD candidate, Caltech: This is actually not correct. Invasion of CO2 into the ocean does not change its alkalinity at all. By adding carbonic acid, and keeping alkalinity constant (defined as either the difference between dissolved cations and anions, or the excess of acid-base species at the CO2 equivalence point), the pH decreases. “seawater has a large buffering capacity which prevents dramatic shifts in pH;” Adam Subhas PhD candidate, Caltech: This is true; however, the amount of CO2 emitted by humans is also massive, a large portion of which has already been absorbed by the oceans. Since pH is relatively insensitive to changes in CO2, it is often not the right parameter to look at in the whole system. For example, over the range of pH values which the author states are found in natural seawater, the surface pCO2 changes from 180 ppm (pH 8.3) to 1500 ppm (pH 7.5). Thus, a mean change in ocean pH of 0.3 pH units represents almost a tripling of seawater pCO2. 2. Decreasing ocean pH is documented to pose significant risks to marine ecosystems, though the magnitude of the impacts depends on specific species. “[…]The impact on calcification, metabolism, growth, fertility and survival of calcifying marine species when pH is lowered up to 0.3 units […] is beneficial, not damaging. Marine life has nothing whatsoever to fear from ocean acidification.” Ken Caldeira Senior Scientist, Carnegie Institution for Science: There is much evidence available to falsify this statement. Many experiments have shown substantial negative biological responses at these levels of pH change. Of course, some organisms are relatively unaffected by these levels. An older review that is available here without a paywall: Langdon (2002) Review of experimental evidence for effects of CO2 on calcification of reef builders. In Proc. 9th Int. Coral Reef Sym. “Then it will destroy all the species that depend on it — causing an almighty mass extinction which will wipe out the fishing industry and turn our oceans into a barren zone of death.” Jean-Pierre Gattuso Research Professor, CNRS, Université Pierre et Marie Curie and IDDRI: That is not a truthful summary of the scientific literature. Check, for example, the meta-analysis of Kroeker et al. (2013) who describe processes and organisms that do not seem to be affected by ocean acidification. Kroeker et al. (2013) Impacts of ocean acidification on marine organisms: quantifying sensitivities and interaction with warming. Global Change Biology. “a killer analysis conducted by Craig Idso of all the studies which have been done on the effects of reduced pH levels on marine life.” Jean-Pierre Gattuso Research Professor, CNRS, Université Pierre et Marie Curie and IDDRI: This publication is not peer-reviewed, cherry-picks articles and does not involve proper statistical testing. It does not, therefore, qualify as a “killer analysis”! The comprehensive metanalysis that was performed by Kroeker et al. (2013) revealed decreased survival, calcification, growth, development and abundance in response to acidification when the broad range of marine organisms is pooled together. However, the magnitude of these responses varies among taxonomic groups. Kroeker et al (2013) Impacts of ocean acidification on marine organisms: quantifying sensitivities and interaction with warming. Global Change Biology. Richard Feely Senior Scientist, NOAA's Pacific Marine Environmental Laboratory: The Idso meta-analysis described by Delingpole was never published. It does not take into account the proper method of proportional scaling analysis. It does not demonstrate how negative effects will impact ecosystem services and food-web processes that can have an effect on economically important fish and shellfish. It does not address the impacts we are already seeing on important fish food, such as pteropods (see Bednarsek et al., 2012, 2014; Feely et al., 2016). There are several highly credible published meta-analysis studies (Kroeker et al. ,2013; Wittman & Pörtner, 2013; and Busch and McElhany, 2016) that have told a much different story than Idso’s unpublished work. Delingpole failed to even mention these other studies, which show very significant impacts on several marine taxa. In summary, Delingpole’s article demonstrates a complete lack of appreciation of scientific literature on this topic and the proper choice of scientific methods for data analysis and synthesis that leads to a more accurate understanding of the present-day and future impacts of ocean acidification. Bednaršek et al (2012) Extensive dissolution of live pteropods in the Southern Ocean,Nature Geoscience Bednaršek et al (2014) Limacina helicina shell dissolution as an indicator of declining habitat,Proc. of the Royal Society B Feely et al (2016) Chemical and biological impacts of ocean acidification along the west coast of North America,Estuarine, Coastal and Shelf Science “First, marine species that calcify have survived through millions of years when CO2 was at much higher levels; second, they are more than capable of adapting — even in the short term — to environmental change” Ken Caldeira Senior Scientist, Carnegie Institution for Science: Many marine organisms respond to changes in calcium carbonate mineral saturation states. These depend not only on pH, but also on factors including amounts of carbon and calcium in the ocean. One of the most important factors is ocean alkalinity, which varies on time scale of many thousands of years. In the geologic past, when atmospheric CO2 was high, ocean alkalinity was also high, and so carbonate mineral saturation states could remain high. Unfortunately, on the timescale of centuries or decades, changes come too fast for the ocean’s natural processes to buffer ocean carbonate mineral saturation states. Directly comparing effects of high CO2 levels that developed in the geologic past over many millions of years with high CO2 levels developing today over decades and centuries shows a fundamental lack of understanding of well-established global geochemical cycles. This open access article explains some of the relevant chemistry: Cao et al (2016) Simulated effect of deep-sea sedimentation and terrestrial weathering on projections of ocean acidification,Journal of Geophysical Research Oceans Jean-Pierre Gattuso Research Professor, CNRS, Université Pierre et Marie Curie and IDDRI: Some calcifying species were indeed abundant in the Cretaceous, a time at which the atmospheric CO2 concentration was high. However, seawater alkalinity was also high due to intense weathering on land. Hence, the concentration of carbonate ions (CO3, which controls calcification) was elevated. That compensation does not happen today and will not happen in the near future because total alkalinity does not change significantly on time scales of centuries. There is ample evidence in the literature for that. Some fast-growing species are indeed able to develop some level of adaptation after several hundreds of generation. Overall, there is evidence that all past episodes of ocean warming, acidification and deoxygenation have led to mass extinctions. Furthermore, there is no calcifier close to CO2 vents, suggesting that adaptation has limited capabilities. 3.The article contains other inaccuracies and misrepresentations of its sources. “if oceans do become warmer due to ‘climate change’, the effect will be for them to ‘outgas’ CO2, not absorb more of it” Jean-Pierre Gattuso Research Professor, CNRS, Université Pierre et Marie Curie and IDDRI: Incorrect: The effect of warming is completely overwhelmed by the effect of increased atmospheric CO2. Hence, the ocean will continue to absorb massive amounts of CO2 in the future, despite ocean warming. “[ocean acidification was ] First referenced in a peer-reviewed study in Nature in 2003” Jean-Pierre Gattuso Research Professor, CNRS, Université Pierre et Marie Curie and IDDRI: The expression “ocean acidification” was actually introduced in 2001 by Broecker and Clark*. But the chemical processes involved have been know for a very long time at least the 1950s) and the impact of low pH (elevated acidity) on marine organisms since the early 1900s. The earliest experiments even predate the definition of pH by Sørensen in 1909. Broecker & Clark (2001) A dramatic Atlantic dissolution event at the onset of the last glaciation, Geochemistry Geophysics Geosystems “Howard Browman, a marine scientist for 35 years, has published a review in the ICES Journal of Marine Science of all the papers published on the subject. His verdict could hardly be more damning. The methodology used by the studies was often flawed; contrary studies suggesting that ocean acidification wasn’t a threat had sometimes had difficulty finding a publisher. There was, he said, an ‘inherent bias’ in scientific journals which predisposed them to publish ‘doom and gloom stories’.” Howard Browman Principal Research Scientist, Norwegian Institute of Marine Research: The following decomposition of this excerpt from Mr. Delingpole’s article in The Spectator identifies inaccuracies in his reporting that lead to misrepresentation of the content and intent of my article. Importantly, Mr. Delingpole never contacted me to verify that his reporting on my article was accurate. Nor was I contacted by the UK’s Independent Press Standards Organisation during their investigation of the accuracy of Mr. Delingpole’s article in The Spectator. “Howard Browman, a marine scientist for 35 years, has published a review in the ICES Journal of Marine Science of all the papers published on the subject.” Howard Browman Principal Research Scientist, Norwegian Institute of Marine Research: The article that Mr. Delingpole is referring to is not “a review”, but an introduction to a special theme issue on the topic of ocean acidification[…] The introduction does not review all of the nearly 4000 articles on the subject. Rather, it presents an overview of the sub-set of research dealing with biological/ecological effects of ocean acidification. “His verdict could hardly be more damning. Howard Browman Principal Research Scientist, Norwegian Institute of Marine Research: On p. 530 of the introduction, I state: “Although I call for a more sceptical scrutiny and balanced interpretation of the body of research on OA [Ocean Acidification], it must be emphasized that OA is happening and it will have effects on some marine organisms and ecosystem processes.” This is hardly a verdict that “…could hardly be more damning.” “The methodology used by the studies was often flawed” Howard Browman Principal Research Scientist, Norwegian Institute of Marine Research: My introduction does not present a quantitative assessment of the frequency of occurrence of methodological flaws in the ocean acidification literature. “There was, he said, an ‘inherent bias’ in scientific journals which predisposed them to publish ‘doom and gloom stories’.” Howard Browman Principal Research Scientist, Norwegian Institute of Marine Research: The words “inherent bias” do not appear in my article. Rather, I refer to “publication bias”. In research, an “inherent bias” is one which is inextricably tied to the core nature of the phenomenon being studied and cannot, therefore, be eliminated by increasing the sample size or choosing a different estimator. “Publication bias”, on the other hand, refers to the general (across all of science) phenomenon by which studies presenting positive results – supporting the hypothesis being tested – are more likely to be published than those reporting negative results. This sometimes creates a situation where published studies may be systematically different from unpublished studies – for example, studies showing an impact of ocean acidification might be published more easily and in higher profile journals than studies showing no impact. However, I only allude to this possibility in the introduction; I do not asses it quantitatively (something that would, in fact, be very difficult to do). Finally, the words “doom and gloom” do not appear in my introduction."
https://science.feedback.org/review/oceans-currently-acidifying-claims-contrary-contradict-observations/,Inaccurate,"The Spectator, James Delingpole, Mike Wallace, 2016-04-30",there has been no reduction in oceanic pH levels in the last century,,Factually wrong: This statement is contradicted by available evidence.  Inadequate support: The basis for the claim is a non-peer-reviewed paper that has been shown to have serious flaws.,The acidity of the upper ocean has increased by about 30% (meaning its pH has dropped about 0.1 units) over the past century due to human emissions of CO2.,there has been no reduction in oceanic pH levels in the last century,,"Tullio Rossi Marine biologist, University of Adelaide: This is plain wrong. Oceanic pH levels decreased by 0.1 units compared to pre-industrial levels. This corresponds to a 30% increase in acidity. For a primer on pH, see this NOAA explainer. Peer-reviewed references: Doney et al (2009) Ocean acidification: the other CO2 problem, Annual Review: of Marine Science Raven et al (2005) Ocean acidification due to increasing atmospheric carbon dioxide, The Royal Society Ken Caldeira Senior Scientist, Carnegie Institution for Science: This statement just flies in both the face of observational facts and a basic understanding of chemistry. I would love to hear a cogent explanation of how atmospheric CO2 levels could rise over the course of a century without producing a decrease in ocean pH. Observations near Hawaii and several other open ocean environments show clear decreasing trends in ocean pH. See, for example this report from the European Environment Agency. It is one thing to challenge future projections, but rejecting well-established scientific facts is another thing entirely. Figure: Decline in pH measured at the Aloha station as part of the Hawaii Ocean time-series. Source Richard Feely Senior Scientist, NOAA's Pacific Marine Environmental Laboratory: Michael Wallace contacted Chris Sabine and myself several years ago and asked how to get access to historical pH measurements in the oceans so he could determine long-term trends of global ocean pH for himself. We directed him to both modern (as published in Feely et al., 2008) and historical pH measurements archived at the NOAA National Centers for Environmental Information. We cautioned him that the earlier data sets prior to 1989 had significant issues with data quality as described in the document that went along with the data set obtained from NCEI. Mr. Wallace went on to perform his analysis of the historical data without regard for the oceanographic community’s concerns about the data quality or for the proper methodology to perform this kind of analysis. He chose to publish his results within the context of an interview written by Marita Noon in the Farmington Daily Times. We responded by correcting the record by formally restating our concerns about Mr. Wallace’s incorrect use of the historical data on our website. In short, Wallace’s chart does not show any kind of useful trend in global ocean pH because the data he used, and the way he used them, were not appropriate for this kind of analysis. In the first place, the pH measurements prior to 1989 were not reliable enough to detect small pH changes over that period. In addition, companion meta data on sensor calibration, pH scales, and temperature corrections were not available. Finally, the data were so limited that no meaningful global averages could be determined. The article by Mr. Delingpole in The Spectator failed to address these important issues, as Philip Williamson correctly points out in his response to the article. CORRECTION (28 Oct. 2018): The takeaway has been updated to clarify that thehydrogen ion concentration (acidity) of the upper ocean has changed by 30%, not the pH (that measures this hydrogen ion concentration on a logarithmic scale). "
https://science.feedback.org/review/arctic-ice-melt-already-affecting-weather-patterns-live-right-now-damian-carrington-the-guardian/,0.6,"The Guardian, by Damian Carrington, on 2016-12-19.",,"""Arctic ice melt 'already affecting weather patterns where you live right now'""",,,,,"This article in The Guardian discusses the influence of Arctic warming on mid-latitude weather patterns. The Arctic is warming faster than the global average, and the possibility that this warming is driving a change in the behavior of the jet stream—and the mid-latitude weather that results—has seen lots of coverage in the past few years. While the article includes interviews with a number of scientists doing research on these patterns, the scientists who reviewed it explained that the conclusions expressed aren’t completely representative of current scientific knowledge: There remains real uncertainty about the link between Arctic warming and certain mid-latitude weather patterns, which the article does not make entirely clear to the reader.See all the scientists’ annotations in contextGUEST COMMENTS: James Screen Associate Professor, University of Exeter: The article nicely introduces some of the emerging science linking Arctic climate change to extreme weather at lower latitudes. There are no major inaccuracies and the author has sought expert comment from several prominent scientists. However, the article fails to fully capture the large uncertainty about how Arctic warming may influence weather in places further south and how big this effect might be. For example, the article draws heavily on a scientific hypothesis that Arctic warming causes a more meandering jet stream and slower moving weather systems (e.g. blocking). This is a credible hypothesis supported by a few peer-reviewed publications (most prominently by one of the scientists interviewed), but there are other papers that have failed to identify such a link, or argued against one. In short, there is no scientific consensus on whether or not Arctic warming causes larger jet stream wiggles or more persistent weather. The jury is still out. Whilst some of the scientist’s quotes do hint at unknowns and ongoing scientific debate, the overall tone of the article gives the impression the science on this topic is more settled than it actually is. Stephen Vavrus Senior Scientist, University of Wisconsin-Madison: I think the writer basically captured the essence of the scientific information provided to him, although some simplifications make the state of the knowledge sound more sweeping than the consensus view in the community. There are skeptical voices in the community whose views differ from those presented in this article. A more complete story could have included them to provide an alternative perspective on the role of a changing Arctic.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Daniel Swain Climate Scientist, University of California, Los Angeles: The author has sought out and quoted relevant experts in the field, and presents specific factual information that is largely accurate regarding a topic that is of considerable interest to both researchers and the public at large. My primary concern with this piece is that it overstates scientific confidence in the linkages between Arctic sea ice loss and mid-latitude weather (especially regarding connections to specific events, like Hurricane Sandy) and fails to make clear that this area remains a topic of very active research. It also uses some language that trends toward hyperbolic, especially in discussing “superstorms”. Jessica Liptak Postdoctoral Research Fellow, University of Michigan: The article spans a wide range of related, but complex topics. Had it focused on just one, such as the potential link between Arctic sea ice melt and midlatitude atmospheric blocking patterns, the writer could have perhaps provided a more thorough summary of what researchers know and, just as importantly, how confident they are in their results. While this article provides insight on how Arctic warming and melting sea ice may affect midlatitude weather, it misleadingly presents the sea ice-albedo feedback as the only contributor to Arctic temperature amplification. Tim Woollings Lecturer, University of Oxford: The article seems to faithfully summarise the views of these scientists. However, this is a relatively small group of researchers, and many in the field would give a more cautious story given current uncertainties. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from the article; comments and replies are from the reviewers. 1. The Arctic is warming faster than the rest of the planet—partly because of the loss of sunlight-reflecting ice and snow, but also for other reasons. “The chain of events that links the melting Arctic with weather to the south begins with rising global temperatures causing more sea ice to melt. Unlike on the Antarctic continent, melting ice here exposes dark ocean beneath, which absorbs more sunlight than ice and warms further. This feedback loop is why the Arctic is heating up much faster than the rest of the planet.” Jessica Liptak Postdoctoral Research Fellow, University of Michigan: This statement correctly identifies how the sea ice-albedo feedback contributes to Arctic temperature amplification, but incorrectly implies that it is the only process responsible for the enhanced warming. While some studies have concluded that the sea ice-albedo feedback is the primary driver of Arctic amplification [1-2]​​, other feedbacks [3-4]​​, internal atmospheric variability, and decadal variations in sea surface temperature and ocean circulation [​5]​​, may have contributed as much, if not more, to the Arctic tropospheric temperature increase. 1. Screen and Simmonds (2010) The central role of diminishing sea ice in recent Arctic temperature amplification, Nature 2. Taylor et al. (2014) A Decomposition of Feedback Contributions to Polar Warming Amplification, Journal of Climate 3. Pithan and Mauritsen (2014) Arctic amplification dominated by temperature feedbacks in contemporary climate models, Nature Geoscience 4. Winton (2006) Amplified Arctic climate change: What does surface albedo feedback have to do with it?, Geophysical Research Letters 5. Perlwitz et al. (2015) Arctic Tropospheric Warming: Causes and Linkages to Lower Latitudes, Journal of Climate 2. The faster rate of warming in the Arctic has the potential to influence weather in the mid-latitudes, but links to specific weather patterns are still topics of active research. “The jet stream forms a boundary between the cold north and the warmer south, but the lower temperature difference means the winds are now weaker. This means the jet stream meanders more, with big loops bringing warm air to the frozen north and cold air into warmer southern climes.” Daniel Swain Climate Scientist, University of California, Los Angeles: The statement regarding what the jet stream is (a “boundary between cold north and warmer south”) is essentially correct, and there is indeed evidence that the north-south temperature difference has decreased in some regions.[1] But there remains considerable scientific uncertainty regarding whether the jet stream is actually “meandering more” in a general sense, and whether these large jet stream meanders are actually caused by sea ice loss.[2-3] 1. Francis and Skific (2015) Evidence for a wavier jet stream in response to rapid Arctic warming, Environmental Research Letters 2. Barnes and Screen (2015) The impact of Arctic warming on the midlatitude jet‐stream: Can it? Has it? Will it?, Wiley Interdisciplinary Reviews: Climate Change 3. Screen and Simmonds (2013) Exploring links between Arctic amplification and mid-latitude weather, Geophysical Research Letters Stephen Vavrus Senior Scientist, University of Wisconsin-Madison: The first sentence is grounded in solid meteorology, since the strength of westerly winds aloft is basically proportional to the north-south temperature difference. The second sentence is also supported by evidence, although not quite as solidly. The sinuosity of the upper-level westerlies generally does vary inversely with the wind speed, but there are exceptions. When the jet stream meanders a lot, then warm air is brought northward and cold air spills southward. “Furthermore, researchers say, the changes mean the loops can remain stuck over regions for weeks, rather than being blown westwards as in the past. This “blocking” effect means extreme events can unfold.” Stephen Vavrus Senior Scientist, University of Wisconsin-Madison: First, I think the word should be “eastwards”, not “westwards”. Second, although the loops do sometimes remain stuck for weeks, the sentence makes it seem as if this is the new normal. Instead, a weaker jet stream ought to increase the persistence on various time scales, but more often being days instead of weeks. The second sentence is partly true, in that atmospheric blocking patterns often do cause extreme weather events, but extreme events can also occur under other conditions, including very strong jet stream winds (e.g. atmospheric rivers). “Severe ‘snowmageddon’ winters are now strongly linked to soaring polar temperatures, say researchers, with deadly summer heatwaves and torrential floods also probably linked.” Daniel Swain Climate Scientist, University of California, Los Angeles: Arctic temperatures have certainly been much higher than the long-term average in recent years, and the extreme warm anomalies this autumn and early winter have been particularly noteworthy. Further, there is a growing body of evidence linking Arctic sea ice loss and/or polar-amplified atmospheric warming to changes in mid-latitude atmospheric circulation*. However, this subject represents a very active area of research and there remains genuine scientific uncertainty regarding specific linkages between ongoing Arctic sea ice loss and specific kinds of extreme weather (like the heatwaves, floods, and snowstorms mentioned here). Moreover, the effects under consideration would likely have different regional manifestations. Therefore, the above statement overstates scientific confidence in such linkages and is overly broad in a geographic sense. Francis and Vavrus (2012) Evidence linking Arctic amplification to extreme weather in mid-latitudes, Geophysical Research Letters Cohen et al. (2014) Recent Arctic amplification and extreme mid-latitude weather, Nature Geoscience Overland et al. (2016) Nonlinear response of mid-latitude weather to the changing Arctic, Nature Climate Change Tim Woollings Lecturer, University of Oxford: “Strongly linked” is an overstatement here. There is some evidence, but I don’t think a majority of climate scientists would make claims as strong as these. “It’s safe to say [the hot Arctic] is going to have a big impact, but it’s hard to say exactly how big right now.” Tim Woollings Lecturer, University of Oxford: This statement is unclear. Arctic warming will clearly have a strong impact on the midlatitudes in the future (certainly by the end of the century). Whether it has had a noticeable effect so far is a lot less clear. “In those years, the jet stream deviated deeply southwards over those regions, pulling down savagely cold air. Prof Adam Scaife, a climate modelling expert at the UK’s Met Office, said the evidence for a link to shrinking Arctic ice was now good: ‘The consensus points towards that being a real effect.’” Stephen Vavrus Senior Scientist, University of Wisconsin-Madison: The first sentence is correctly describing how the jet stream tends to move equatorward during the negative phase of the North Atlantic (or Arctic) Oscillation [NAO and AO, respectively], which was very prevalent in those years. Negative phases of the NAO or AO strongly promote more extreme cold in middle latitudes during winter. As for a “consensus”, that depends a lot on who you ask. This topic of potential Arctic-middle latitude connections is a controversial one, so there isn’t a lot of consensus on the overall role of the Arctic at this point. I think the closest we have to a consensus is the persuasive evidence that sea ice loss in the Barents-Kara Seas during autumn-winter promotes extreme cold downstream over eastern Asia via a stronger Siberian High Pressure Cell. Tim Woollings Lecturer, University of Oxford: This refers to a southward shifted jet in response to sea ice loss (a negative North Atlantic Oscillation pattern). It’s not clear at all that this is the same kind of behaviour as suggested by the quoted scientists. “The connection between the vanishing Arctic ice and extreme summer weather in the northern hemisphere is probable, according to scientists, but not yet as certain as the winter link.” Tim Woollings Lecturer, University of Oxford: The winter link is not certain either. As above, there is some evidence for a North Atlantic Oscillation response but still several conflicting studies. Stephen Vavrus Senior Scientist, University of Wisconsin-Madison: Again, it depends who one talks to about whether “probable” is the correct term. There have been numerous articles making this claim and providing plausible evidence for it, but a well-accepted physical explanation has yet to be established, in my opinion. The dynamical mechanisms linking sea ice anomalies to mid-latitude weather during winter are easier to understand than those during summer. Different but more complex linkages might well exist during summer to explain some of the observational evidence correlating sea ice anomalies with extreme summer weather. “Another consequence of the fast melting Arctic raises the possibility that there may be even worse extreme weather to come, according to a few scientists: titanic Atlantic superstorms and hurricanes barreling across Europe.” Daniel Swain Climate Scientist, University of California, Los Angeles: This statement does not accurately describe an outcome that is widely supported in the scientific literature. It is certainly true that Arctic sea ice is decreasing at a rapid rate, and that further sea ice loss is highly likely in the future. It is also plausible, and supported by existing research, that present and future sea ice loss may alter the atmospheric circulation in ways that affect the likelihood of certain kinds of weather events*. But the claim regarding “Atlantic superstorms” and “hurricanes barreling across Europe” seems fairly hyperbolic. Overland et al. (2016) Nonlinear response of mid-latitude weather to the changing Arctic, Nature Climate Change Kug et al. (2015) Two distinct influences of Arctic warming on cold winters over North America and East Asia, Nature Geoscience Zhang et al. (2016) Persistent shift of the Arctic polar vortex towards the Eurasian continent in recent decades, Nature Climate Change “This means a region of the north Atlantic is becoming relatively cool and this exaggerates the contrast with tropical waters to the south, which is the driver for storms. In the worst case scenario, said the renowned climate scientist Prof James Hansen, this ‘will drive superstorms, stronger than any in modern times – all hell will break loose in the north Atlantic and neighbouring lands’.” Tim Woollings Lecturer, University of Oxford: I agree that the superstorm suggestion is very speculative. In one paper we looked at a similar scenario and saw a clear increase in the number of storms, but not their intensity, though that was just in one climate model. Brayshaw and Woollings (2009) Tropical and Extratropical Responses of the North Atlantic Atmospheric Circulation to a Sustained Weakening of the MOC, Journal of Climate “I would certainly not call such [superstorm] scenarios ridiculous,” said Coumou. “But it is speculative – we don’t have the hard evidence.” James Renwick Professor, Victoria University of Wellington: The superstorm scenario rests on a number of assumptions, especially that the rate of ice melt from Greenland (and Antarctica) will accelerate very rapidly. Definitely still in the realm of speculation."
https://science.feedback.org/review/stunning-new-data-indicates-el-nino-drove-record-highs-global-temperatures-david-rose-daily-mail/,-1.9,"Daily Mail, by David Rose, Judith Curry, on 2016-11-26.",,"""Stunning new data indicates El Nino drove record highs in global temperatures...""",,,,,"Contrary to what this article implies, the long term global temperature rise is known to be mostly due to human emissions of greenhouse gases. A strong El Niño event helped set a new record in annual global surface temperature in 2015 (and likely again in 2016) by boosting global temperatures on top of the long-term warming trend. This article is a textbook case of cherry picking—it selects only one record, ignores the limitations of the data it comments on, and forms an argument based on only a few months of a much longer record. This is akin to claiming that sea level rise has ended because high tide in one area has ebbed.See all the scientists’ annotations in context The article has been originally published by The Mail on Sunday and then published online on the Daily Mail‘s website. GUEST COMMENTS: Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: This is an incredibly misleading article. It cherry picks a dataset taking measurements 2 miles up in the atmosphere only over land areas that disagrees with the other two datasets that examine the same values. The author of the dataset they use specifically warns against using it due to errors in measurement times. Literally all other surface and satellite datasets show no corresponding massive decline, either over land or globally. The author is taking a normal modest cooling at the end of a large El Niño event and spinning it completely out of proportion. In reality, 2014, 2015, and 2016 have been the three warmest years on record not just because of a large El Niño, but primarily because of a long-term warming trend driven by human emissions of greenhouse gases. The modest decline in temperatures in recent months from the peak of the El Niño event is completely in line with what has happened during past large El Niño events and was expected by scientists. Stephan Lewandowsky Professor, University of Bristol: This article is flawed to perfection. Mr. Rose made the following inadvisable choices: 1. Ignore the surface temperature record and use only satellite data. Satellites do not measure temperature, they measure microwave radiation, which can be related to an estimate of temperature by use of a computer model. The resulting estimate is, however, not only of temperature at the surface of the Earth—which is where we live—but includes temperature at altitudes of thousands of feet—where no one is trying to farm or grow tomatoes. 2. Ignore two-thirds of the satellite record. Most of the Earth is covered in ocean, and global warming is called global warming because it is global—that is, it includes the oceans. 3. Ignore the trend and focus on two data points. A long-standing trick of people who deny the overwhelming scientific consensus regarding climate change is to cherry-pick isolated observations. The only way to support the claim of a 1-degree drop in the satellite record is by comparing February 2016 to October 2016. This drop, however, is merely weather that is superimposed on the long-term climatic trend. Steven Sherwood Professor, University of New South Wales: The discussion in the article of a disagreement among scientists as to whether the record-breaking global heat in 2015 and again in 2016 was “due to El Niño” vs. “due to global warming” is completely bogus. Both global warming and El Niño, added together, produced these records. El Niño by itself could never have produced such a warm planet as we have now. Everyone, including NASA’s Gavin Schmidt, has been pointing out for some time that temperatures would dip for a while once the El Niño faded, but that’s just a bump on the road to a warmer and warmer planet. REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Ed Hawkins Principal Research Fellow, National Centre for Atmospheric Science: Overall the article is made highly misleading by omitting critical information and cherry-picking one particular dataset and time period. It also incorrectly interprets comments from climate scientists. Benjamin Horton Professor, Earth Observatory of Singapore: The claim that global land temperatures have plunged by a record margin is false because: (1) the author cherry picks the data, relying on the satellite record of Earth’s temperature, which only dates to 1978 rather than the surface temperature record which dates to the 19th century. Using the full dataset the decrease in land-based temperature is NOT a record drop; (2) the author IGNORES THE OCEANS. When combining both the land and ocean, there is not a record fall in the satellite record; and (3) the surface temperature record shows an unmistakably upward trend, irrespective of year-to-year wiggles. Victor Venema Scientist, University of Bonn, Germany: It is a pity the rating scale does not allow for rating below “very low”. Had the article honestly shown a graph of the global surface temperature increase in the last century every reader would have seen how deceptive David Rose’s article is. Kyle Armour Assistant Professor, University of Washington: It is well known that global temperature falls after receiving a temporary boost from El Niño. The author cherry-picks the slight cooling at the end of the current El Niño to suggest that the long-term global warming trend has ended. It has not. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from David Rose; comments and replies are from the reviewers. 1.Recent record global surface temperatures are primarily the result of the long-term, human-caused warming trend. A smaller boost from El Niño conditions has helped set new records in 2015 and 2016. “Some scientists, including Dr Gavin Schmidt, head of Nasa’s climate division, have claimed that the recent highs were mainly the result of long-term global warming.” Victor Venema Scientist, University of Bonn, Germany: Dr. Gavin Schmidt, who is head of NASA’s Goddard Institute for Space Studies and not any of the NASA divisions, is right. The long-term warming of about 1°C globally—and more over land or in the Northern Hemisphere—is much larger than the El Niño fluctuations. Source: Global Warming Index “Others have argued that the records were caused by El Nino […] The new fall in temperatures suggests they were right.” Ed Hawkins Principal Research Fellow, National Centre for Atmospheric Science: Incorrect. We have seen more than 1°C of warming which is largely due to human activities. The strong El Niño has added around 0.1°C temporarily. Therefore, the largest cause of the record temperatures is human activities. “This means it is possible that by some yardsticks, 2016 will be declared as hot as 2015 or even slightly hotter – because El Nino did not vanish until the middle of the year.” Victor Venema Scientist, University of Bonn, Germany: It is virtually certain that 2016 will be warmer than 2015. See for example this estimate of the 2016 average temperature based on the GISS data up to October. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: Even without the big El Niño spike, 2016 will be the hottest year on record, and 2015 the second hottest. Scientists have methods to remove the effect of El Niño on the temperature record. We can also see this in a simple example where we just remove the big El Niño-related temperature spike, but 2016 remains the warmest year in the surface temperature record: “Dr. Schmidt also denied that there was any ‘pause’ or ‘hiatus’ in global warming between the 1998 and 2015 El Ninos.” Victor Venema Scientist, University of Bonn, Germany: If you want to cherry pick 1998 as the beginning year—a year in which the temperature was high due to El Niño—it would at least be fair to stop in 2016, not 2015, because 2016 is the year that the temperatures were highest due to El Niño. If you do so, there is clearly no “slowdown”. Better would be not to cherry-pick a specific period. The long-term trend is clearly warming and statistics do not indicate any decline in the warming rate. Since 2016, I would argue you no longer need statistics to see this. Just look at the complete graph. “Professor Judith Curry, of the Georgia Institute of Technology, and president of the Climate Forecast Applications Network, said yesterday: ‘I disagree with Gavin. The record warm years of 2015 and 2016 were primarily caused by the super El Nino.’” Kyle Armour Assistant Professor, University of Washington: It seems kind of pointless to try to precisely attribute why one year was warmer or cooler than the last; this is basically just due to climate variability (including but not limited to El Niño). The broader point is that all evidence suggests that the long-term global surface warming trend has continued. There is no evidence that the rate of warming since 1998 is statistically different from the long-term trend since 1950. 2. The article makes its case by relying only on cherry-picked data from specific datasets on short periods. “The news comes amid mounting evidence that the recent run of world record high temperatures is about to end.” Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: The modest decline in temperatures in the past few months is a normal reversion after the end of the El Niño event. It has relatively little impact on the longer-term warming trend, which is the most scientifically relevant metric of climate change. Victor Venema Scientist, University of Bonn, Germany: We have had 3 record warm years: 2014, 2015, and likely 2016. Also when Bayern München loses a game, they are still be best team in Germany—when 2017 is not again a record year, global warming will continue. “The fall, revealed by Nasa satellites, has been caused by the end of El Nino” Victor Venema Scientist, University of Bonn, Germany: The temperature estimates come from passive microwave radiometers. These instruments’ prime task is estimating air humidity for meteorology—weather prediction. Thus most of the these instruments actually flew on NOAA satellites. It should be noted that they were not designed to be used for long-term climate monitoring. Steven Sherwood Professor, University of New South Wales: Temperature averages from satellite-based detectors are very noisy, and tend to exaggerate swings due to El Niño compared with other data sources. I would not attach much significance to big upswings or downswings over periods of only a few months, especially when other indicators, like sea ice, are suggesting acceleration of warmth. The long-term upward trend is clear in every source of data we have. “Global average temperatures over land have plummeted by more than 1C since the middle of this year – their biggest and steepest fall on record.” Victor Venema Scientist, University of Bonn, Germany: It is known that El Niño, an oscillation in the tropical Pacific, is a cause of short-term fluctuations of the temperature and precipitation. This should not be confused with long-term warming. This is clearly illustrated by this graph below that shows the warming of El Niño years, La Niña years (the opposite of El Niño), and neutral years individually. Victor Venema Scientist, University of Bonn, Germany: The image in the Daily Mail is deceptive as it only shows the part of the data (in the red box of the graph below). With all the problems of this dataset, it also shows long-term warming if you look at the full period.Ed Hawkins Principal Research Fellow, National Centre for Atmospheric Science: The time series used in the central image is highly misleading, as it only shows some of the data available and therefore disguises the increase seen before the chosen period. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: This is not true for global surface temperatures, not true for land surface temperatures, not true for global temperatures 2 miles up in the atmosphere, and not true for two of the three datasets that provide temperatures 2 miles up in the atmosphere only over land areas. It’s a truly breathtaking example of cherry-picking. Furthermore, the folks who created the dataset that Rose cites (Remote Sensing Systems) note that there is a serious error in their data and warn:“The lower tropospheric (TLT) temperatures have not yet been updated at this time and remain V3.3. The V3.3 TLT data suffer from the same problems with the adjustment for drifting measurement times that led us to update the TMT dataset. V3.3 TLT data should be used with caution.” “According to the satellites, the late 2016 temperatures are returning to the levels they were at after the 1998 El Nino.” Victor Venema Scientist, University of Bonn, Germany: Not based on any evidence. Just like the warming peak due to El Niño was higher in 2016 than in 1998, the period after 2016 will be warmer than the years after 1998 due to the progress of global warming. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: Even according to satellite records, which have their issues, this is not remotely the case:"
https://science.feedback.org/review/daily-mail-claim-2016-global-temperature-record-misleading/,Misleading,"Daily Mail, David Rose, 2016-11-26",El Niño drove record highs in global temperatures suggesting rise may not be down to man-made emissions.,,"Misrepresents a complex reality: Record highs in global surface temperatures in 2016 are due to the superposition of an El Niño event on top of the warming effect of human greenhouse gas emissions, so blaming the record only on El Niño paints a simplistic picture.",The continuing rise of global temperature is mostly due to human emissions of greenhouse gases. A strong El Niño event helped set a new record in annual global surface temperature in 2016.,Stunning new data indicates El Niño drove record highs in global temperatures suggesting rise may not be down to man-made emissions.,,"Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: Even without the big El Niño spike, 2016 will be the hottest year on record, and 2015 the second hottest. Scientists have methods to remove the effect of El Niño on the temperature record. We can also see this in a simple example where we just remove the big El Niño-related temperature spike, but 2016 remains the warmest year in the surface temperature record: The modest decline in temperatures in the past few months is a normal reversion after the end of the El Niño event. It has relatively little impact on the longer-term warming trend, which is the most scientifically relevant metric of climate change. Steven Sherwood Professor, University of New South Wales: Temperature averages from satellite-based detectors are very noisy, and tend to exaggerate swings due to El Niño compared with other data sources. I would not attach much significance to big upswings or downswings over periods of only a few months, especially when other indicators, like sea ice, are suggesting acceleration of warmth. The long-term upward trend is clear in every source of data we have. Victor Venema Scientist, University of Bonn, Germany: It is known that El Niño, an oscillation in the tropical Pacific, is a cause of short-term fluctuations of the temperature and precipitation. This should not be confused with long-term warming. This is clearly illustrated by this graph below that shows the warming of El Niño years, La Niña years (the opposite of El Niño), and neutral years individually."
https://science.feedback.org/review/great-barrier-reef-australia-coral-die-off-doyle-rice-usa-today/,1.6,"USA Today, by Doyle Rice, on 2016-11-29.",,"""Australia’s Great Barrier Reef has worst coral die-off ever""",,,,,"This article in USA Today reports on the latest survey of mass coral bleaching on the Great Barrier Reef released by the Australian Research Council Centre of Excellence for Coral Reef Studies. This year, the northern portion of the reef has seen the worst bleaching ever observed with two-thirds of coral dead on average—even more in some locations. Southern sections of the reef experienced much less bleaching and death because of slightly cooler water. The article correctly notes that climate change is making this kind of mass bleaching event more frequent, putting tropical reefs at risk. Reefs are ecosystems incredibly rich in biodiversity, and they provide economic value through tourism, fishing, and protection against coastal erosion.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Mark Eakin Scientist, Coordinator of NOAA’s Coral Reef Watch, National Oceanic and Atmospheric Administration: In general, the article got this one almost completely right, with one of my two quibbles being in one of the experts’ quotes. It is unfortunate, however, that the article didn’t put this story in the context of the global coral bleaching event that is still underway—currently hitting hardest in Micronesia and the Marshall Islands. Katrin Meissner Professor, University of New South Wales: This article is mostly accurate. The author made one overstatement (that we will see yearly massive bleaching events at the Great Barrier Reef within the next decade). It should be noted, though, that the frequency of massive bleaching events is increasing, will continue to increase in the near future, and that these events do not need to occur annually to kill the reef. The variability of El Niño Southern Oscillation on top of the background warming trend of surface temperatures means that we will exceed the bleaching thresholds more frequently. In the future, the reefs won’t have time to recover between these events. James Renwick Professor, Victoria University of Wellington: This is a very good article highlighting one of the world’s biodiversity hotspots and the grave risks it faces. One of two of the comments and ideas are off the mark, but it is largely factually correct. Lauren Simkins Assistant Professor, University of Virginia: Coral bleaching is a visual reminder of the influence of climate change on the world’s oceans and ecosystems. The article presents findings that support a massive bleaching event this year and some of the ecological and economic consequences of coral bleaching. Although lacking in key scientific references to support claims, the article is insightful and unbiased. John Bruno Professor, The University of North Carolina at Chapel Hill: I concur with my colleagues that this is mostly an accurate article. A few points are exaggerated, as we all noted in the annotated version. And to be clear, this may well be the worse die off on the Great Barrier Reef, but we’ve been seeing die offs of this magnitude and geographic scope around the world for decades. For example, coral reefs across the Caribbean experienced a die off of similar-to-larger scope 35 years ago. My entire career, I’ve been studying “post mass-coral die off” reefs in Jamaica, Belize, Cuba, etc. So in this regard, the event isn’t especially notable. The real lesson of the GBR coral mortality of 2016 isn’t that ocean warming is causing mass-coral die offs – we’ve known that for a quarter century. It is that even the world’s most remote, well-managed, and otherwise pristine reefs are susceptible. Many of my colleagues have assumed and argued that ocean warming only causes mass coral mortality in the presence of other insults to the reef. Stressors like overfishing, pollution, tourism, etc. that were believed to weaken “natural resilience” to ocean warming. I co-authored a paper earlier this year* that found that reef isolation had no effect on coral loss – the world’s most isolated reefs, free from local human impacts, were just as degraded in terms of the amount of remaining living coral as reefs adjacent to large population centers. The bottom line is that no form of local management can save reefs from carbon emissions. Bruno and Valdivia (2016) Coral reef degradation is not correlated with local human population density, Nature scientific reports.Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from Doyle Rice; comments and replies are from the reviewers. 1.This year, the northern section of Australia’s Great Barrier Reef experienced the worst bleaching of corals ever observed. (Corals “bleach” when water temperatures increase beyond a tolerable range.) “Scientists confirm a mass bleaching event on the Great Barrier Reef this year has killed more corals than ever before, with more than two thirds destroyed across large swathes of the biodiverse site.” Mark Eakin Scientist, Coordinator of NOAA’s Coral Reef Watch, National Oceanic and Atmospheric Administration: Actually, this is an underestimate as the “25% of the worst affected reefs (the top quartile), losses of corals ranged from 83-99%.” How much coral has died in the Great Barrier Reef’s worst bleaching event? “When water temperatures become too high, coral becomes stressed and expels the algae, which leave the coral a bleached white color.” Mark Eakin Scientist, Coordinator of NOAA’s Coral Reef Watch, National Oceanic and Atmospheric Administration: The article should have noted that, while injured and starving, bleached corals are still alive. When thermal stress is severe or prolonged, corals often die. Thermally-stressed corals also frequently die due to disease outbreaks. NOAA Coral Reef Conservation Program Infographic Gallery Burge et al (2014) Climate Change Influences on Marine Infectious Diseases: Implications for Management and Society, Annual Review: of Marine Science “The good news, scientists said, was that central and southern sections of the reef fared far better, with “only” 6% and 1% of the coral dead, respectively.” Mark Eakin Scientist, Coordinator of NOAA’s Coral Reef Watch, National Oceanic and Atmospheric Administration: The pattern of warming this year resulted in the highest thermal stress being located in the northern part of the Great Barrier Reef. This can be seen in the coral bleaching products from NOAA’s Coral Reef Watch. Source: NOAA Coral Reef Watch 2.Global warming is raising seawater temperatures, leading to episodes of widespread coral bleaching. These episodes typically occur during El Niño conditions, which regionally boost water temperature further. “Stress from unusually warm ocean water heated by man-made climate change and the natural El Niño climate pattern caused the die-off.” Julia Cole Professor, The University of Arizona: Yes, human-caused warming boosts the background temperature, so that warming associated with El Niño can now reach levels intolerable by corals. Mark Eakin Scientist, Coordinator of NOAA’s Coral Reef Watch, National Oceanic and Atmospheric Administration: Roughly speaking, the El Niño may have added a quarter of a degree C to the global average in 2015/16, while the greenhouse-gas-related warming trend has added twice that much to the average values since the 1980s. It’s also important to note that this is only one part of a global coral bleaching event that has been occurring since mid-2014. NOAA declares third ever global coral bleaching event “Mass coral bleaching is a new phenomenon and was never observed before the 1980s as global warming ramped up.” Mark Eakin Scientist, Coordinator of NOAA’s Coral Reef Watch, National Oceanic and Atmospheric Administration: Correct. Baker et al (2008) Climate change and coral reef bleaching: An ecological assessment of long-term impacts, recovery trends and future outlook, Estuarine, Coastal and Shelf ScienceJulia Cole Professor, The University of Arizona: On the Great Barrier Reef, I believe this is true. Global (especially tropical) temperatures took a jump upwards in the late 1970s, providing the extra warmth that puts corals in danger. “[…]looking to the future, mass coral bleaching on the Great Barrier Reef will likely be an annual phenomenon within a decade, Torda said.” Mark Eakin Scientist, Coordinator of NOAA’s Coral Reef Watch, National Oceanic and Atmospheric Administration: This may turn out to be true but most studies place annual bleaching, especially on the Great Barrier Reef, a bit further out—perhaps 2050. van Hooidonk et al (2013) Temporary refugia for coral reefs in a warming world, Nature Climate ChangeKatrin Meissner Professor, University of New South Wales: This sentence is an overstatement. See, for example, Meissner et al. (2012)*: “By year 2030, 66–85% of the reef locations considered in this study would experience severe bleaching events at least once every 10 years. Regardless of the concentration pathway, virtually every reef considered in this study (>97%) would experience severe thermal stress by year 2050.” Having said that, mass coral bleaching events do not need to be an annual phenomenon to kill the reef. Coral reefs need years to recover from extreme bleaching events, which means that even a decadal occurrence of severe bleaching will not give the reef enough time to ever recover. While this sentence is an overstatement, the impact on the reef is the same. Meissner et al (2012) Large-scale stress factors affecting coral reefs: open ocean sea surface temperature and surface seawater aragonite saturation over the next 400 years, Coral Reefs"
https://science.feedback.org/review/higher-global-temperatures-sea-ice-record-lows-poles-brandon-miller-cnn/,2,"CNN, by Brandon Miller, on 2016-11-19.",,"""Amid higher global temperatures, sea ice at record lows at poles""",,,,,"This CNN article discusses the unprecedented recent warm sea surface and air temperatures leading to the record low Arctic extent. It also explores the potential influence this long-term trend of sea ice loss may have on the polar vortex and weather patterns in the midlatitudes. Scientists reviewing the article found that it is an accurate and insightful summary of current scientific knowledge, which indicates that warming is driving a long-term decline in Arctic sea ice coverage—though sea ice at both poles is subject to shorter-term variability, as well.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Michel Tsamados Lecturer (Assistant Professor), University College London: The article does a good job of conveying our current understanding of the state of the sea ice in the 21st century. The very low total Arctic and Antarctic sea ice extent in October 2016 is a clear outlier with respect to the last ~40 years. Such an extreme event is a combination of particular weather patterns in both hemispheres superimposed on the rapid temperature rise observed in the Arctic (at twice the global rate – the so called ‘polar amplification’). Jan Lenaerts Assistant Professor, University of Colorado, Boulder: Well outlined and balanced article, describing the evident link between low sea ice and climate warming and the melt-albedo feedback, but also mentioning the role of weather and short-time variability. Jennifer Francis Senior Scientist, Woods Hole Research Center: This is an excellent summary of the Arctic’s bizarre behavior recently and through most of 2016. James Renwick Professor, Victoria University of Wellington: An excellent explainer piece. Well written and grounded in science. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from Brandon Miller; comments and replies are from the reviewers. 1. Arctic sea ice extent is declining rapidly as a result of climate change. Antarctic sea ice is expected to shrink eventually as well, but has been so far more influenced by natural variability. “While record low sea ice is nothing new in the Arctic, this is a surprising turn of events for the Antarctic. Even as sea ice in the Arctic has seen a rapid and consistent decline over the past decade, its counterpart in the Southern Hemisphere has seen its extent increasing.” James Renwick Professor, Victoria University of Wellington: Exactly. The “upward trend” has been big news, but in the last two years, sea ice extent around the Antarctic has taken a nose-dive. Sea ice extent anomalies for the months ofOctober (1979-2016) in the Antarctic (up) and Arctic (down). Source: NSIDC “Skeptics have long pointed to ice gain in the Southern Hemisphere as evidence climate change wasn’t occurring, but scientists warned that it was caused by natural variations and circulations in the atmosphere.” Jan Lenaerts Assistant Professor, University of Colorado, Boulder: This is slightly confusing, since it can refer to either sea ice gain or land ice gain (which were both mentioned by “skeptics”). The sea ice gain since 2000 has been attributed to natural, decadal variability in the tropical Pacific*. Land ice gain is a false claim, and mostly refers to slight thickening of the East Antarctic interior, which is more than compensated by dynamic ice loss in West Antarctica. Meehl et al (2016) Antarctic sea-ice expansion between 2000 and 2014 driven by tropical Pacific decadal climate variability, Nature Geoscience “It “certainly puts the kibosh on everyone saying that Antarctica’s ice is just going up and up,” Meier said.” Michel Tsamados Lecturer (Assistant Professor), University College London: I agree that the statement that Antarctic sea ice going up and up is a misconception when looked at over larger time scales. On the other hand it is also true that over the satellite area Antarctic sea ice has increased in extent (a bit) every month of the year (see NSIDC time series) October is probably the month with the weakest positive trend. Therefore I believe that it is more important to explain that while the transient response of Antarctic sea ice is more complex than in the Arctic, the end state (equilibrium) is also one with polar amplification, increased temperatures and sea ice decline, in both hemisphere. “For what appears to be the first time since scientists began keeping track, sea ice in the Arctic and the Antarctic are at record lows this time of year.” Michel Tsamados Lecturer (Assistant Professor), University College London: While we have a very clear picture of the sea ice concentration only over the satellite era (1979-present) there are other measurements available that are more or less direct, ranging from whaling and shipping log books (showing higher sea ice extent over the past 100 years) to paleo-climate reconstruction (proxies) over thousands to million of years. [more about ‘polar amplification’ in past climate] “It’s far too early to tell if what we are seeing in the Arctic, and now the Antarctic, is a sharp shift towards warmer poles with less ice. Scientists are quick to point out that weather in these regions can change quickly, but this is another expected result of climate change.” Julienne Stroeve Senior Research Scientist, University College London: Certainly the loss of sea ice is largely a result of warming from increased atmospheric concentrations of CO2. So it’s not surprising to see the changes in the Arctic. Climate models also predict that Antarctic sea ice will decline eventually, especially once the ozone hole recovers. There is some evidence* that the ozone hole has led to stronger circumpolar winds that spread the Antarctic sea ice cover out from the continent and since there is no land to bound the sea ice (like in the Arctic) it can expand towards the equator until it reaches warmer ocean temperatures. Arblaster and Meehl (2006) Contributions of External Forcings to Southern Annular Mode Trends, Journal of Climate Turner and Overland (2009) Contrasting climate change in the two polar regions, Polar Research 2. The current lack of Arctic sea ice growth can be partly explained by the “ice-albedo” feedback—the fact that with less sea ice, the exposed ocean water is able to absorb more solar energy, accelerating the warming and melting process. “‘The interaction between Arctic ocean temperatures and the loss of ice formation leading to continuing record minimums is clearly a climate change signal,’ said Thomas Mote, a geography research professor at the University of Georgia.” James Renwick Professor, Victoria University of Wellington: Yes. The “ice-albedo feedback” has been evident in the Arctic for some years, contributing to “polar amplification”—the effect where polar latitudes warm at around twice the rate of the globe as a whole. “Temperatures in the Arctic have soared recently, and scientists are struggling to explain exactly why.” Jennifer Francis Senior Scientist, Woods Hole Research Center: The only quibble I have with this article is this statement. I’d say that we have a fairly good understanding of the causes of this warm episode. As mentioned in the article, a very diminished ice cover this summer allowed additional solar energy to be absorbed by the Arctic Ocean, which is then released back to the atmosphere in fall that in turn retards refreezing. Additional moisture is also evaporated from the open ocean, which not only traps additional heat as a greenhouse gas, but also tends to form more clouds that also trap heat. An unusually wavy jet-stream pattern has also transported extra heat and moisture from lower-latitude regions into the Arctic, adding to the warmth. We know many self-reinforcing mechanisms operate in the Arctic, so when some heat shows up there (think greenhouse gases, moisture, etc.), its effects are amplified. This has been understood for a long time, but perhaps the pace of this warming is somewhat unexpected. “To make matters worse, the water temperatures in the Arctic Ocean are several degrees above average, which is an expected result of having less sea ice.” Julienne Stroeve Senior Research Scientist, University College London: Generally, the absorbed solar radiation leads to enhanced ocean temperatures in the mixed layer, so with summers of less ice the ocean mixed layer temperatures are usually warmer than average. Though even that is more driven by the timing of when the sea ice retreats. If it retreats early in the melt season when the sun is still high in the sky then you get more ocean warming, but if like in 2012 the ice retreats rapidly in August, it doesn’t have the same impact on ocean temperatures because the sun is already starting to set. But while this may be part of the explanation for warmer ocean temperatures at the moment, in the Barents Sea it is actually a result of warm Atlantic waters entering the Arctic. I have spoken with oceanographers about this and the sea surface temperature anomalies are a result of stronger inflow to the Barents Sea and along the west coast of Svalbard. The strong northwards flow of Atlantic water is also consistent with the more southerly winds this November that have helped to bring in warm air temperatures."
https://science.feedback.org/review/the-phony-war-against-co2-the-wall-street-journal-rodney-nichols-harrison-schmitt/,-2,"The Wall Street Journal, by Harrison Schmitt, Rodney Nichols, on 2016-10-31.",,"""The Phony War Against CO2""",,,,,"This commentary in the Wall Street Journal by Rodney Nichols and Harrison Schmitt tries to argue that CO2 emitted by humans is, overall, “beneficial”–particularly for agriculture. To do so, the authors ignore all the evidence of the negative impacts of increasing CO2 concentrations in the atmosphere (due to climate change and ocean acidification, for example). The commentary relies on claims that are not supported by any evidence, like the assertion that more CO2 in the atmosphere has helped to reduce poverty. The authors invite the reader to “check the facts” but do not apply that maxim to themselves. Instead of referring to published scientific research, the article draws heavily from information created by an advocacy group that exists to promote CO2 emissions as beneficial. Taken as a whole, the body of scientific evidence clearly shows that this is not the case.See all the scientists’ annotations in contextGUEST COMMENTS: Wolfgang Cramer Professor, Directeur de Recherche, Mediterranean Institute for Biodiversity and Ecology (IMBE): The article speaks about scientific questions under an “opinion” banner—as if questions about the role of CO2 in the Earth system could be a matter of opinions. Virtually every single point in the article can be easily proven wrong by referral to standard textbook knowledge. For the major final conclusion “With more CO2 in the atmosphere, the challenge [to feed additional 2.5 billion people] can and will be met.“, there is absolutely no scientific credibility, nor support in the scientific literature—it is pure fantasy.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. William Anderegg Associate Professor, University of Utah: The opinion article makes sweeping assertions that are not in line with the scientific understanding. The conclusions on CO2 uniformly benefiting agriculture are simply misleading—yes, CO2 can help plants but higher temperatures and more drought and pests with climate change also hurt plants. Timothy Osborn Professor, University of East Anglia, and Director of Research, Climatic Research Unit: The article presents a biased view by understating the degree and impacts of global warming while overstating or simplifying the benefits of CO2 fertilisation. James Renwick Professor, Victoria University of Wellington: The article is full of half-truths, untruths, and red herrings. Casting increased CO2 as a benefit to humankind, without considering the impacts and risks associated with a changing climate, is dangerous and irresponsible. Lauren Simkins Assistant Professor, University of Virginia: The lack of distinction between the role of solid particulates and greenhouse gases in the atmosphere makes many of the authors’ claims false and misleading. The article does not present a complete or accurate discussion of climate change, its causes, and its societal influence. The authors state that readers should ‘check the facts’ regarding climate change, but have presented us with little scientific support for their own claims. Victor Venema Scientist, University of Bonn, Germany: This has nothing to do with science. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from Harrison Schmitt and Rodney Nichols; comments and replies are from the reviewers. 1. The negative impacts of continued CO2 emissions are significant and serious. The authors only find human emissions of CO2 beneficial by ignoring all the reasons it is harmful. “Unlike genuine pollutants, carbon dioxide (CO2) is an odorless, colorless gas. Every human being exhales about two pounds of CO2 a day, along with a similar amount of water vapor. CO2 is nontoxic to people and animals” Timothy Osborn Professor, University of East Anglia, and Director of Research, Climatic Research Unit: This is a diversionary tactic: the concern about CO2 is not about its smell, its colour or its direct toxicity; instead it is about its effect on the Earth’s climate. So it is a strawman statement that may be easily demolished but not relevant to the concern about CO2 and climate change. Victor Venema Scientist, University of Bonn, Germany: There are many toxic gases that are odorless and colorless. The best known one is, like CO2, also related to combustion: carbon monoxide (CO). “But a myth persists that is both unscientific and immoral to perpetuate: that the beneficial gas carbon dioxide ranks among hazardous pollutants. It does not.” James Renwick Professor, Victoria University of Wellington: This is semantics. Some call carbon dioxide a “pollutant” and others don’t. What is relevant is that the huge amount of CO2 that humanity has put into the atmosphere is changing the climate significantly. The hazard comes from changes to precipitation and extremes, leading to reduced food security and water availability. No wonder the Pentagon rates climate change as a critical threat to US national security. Just look at what’s happening in Syria and north Africa, on the back of a severe drought and a spike in food prices. Reference: Kelley et al (2015) Climate change in the Fertile Crescent and implications of the recent Syrian drought. Proceedings of the National Academy of Sciences “[CO2] is also a greenhouse gas which helps maintain earth at a habitable temperature.” Wolfgang Cramer Professor, Directeur de Recherche, Mediterranean Institute for Biodiversity and Ecology (IMBE): While the presence of CO2 has warmed the atmosphere to “habitable” temperatures, the additional increase of it will bring temperatures way outside habitable ranges in many regions including the oceans, as well as disturbing the water cycle and acidifying the oceans. “But observations, such as those on our CO2 Coalition website, show that increased CO2 levels over the next century will cause modest and beneficial warming—perhaps as much as one degree Celsius (1.8 degrees Fahrenheit)” James Renwick Professor, Victoria University of Wellington: That [1 °C warming] is an absolute best-case scenario, if significant mitigation action is taken urgently. Increased CO2 leads to warming, which leads to increased atmospheric water vapor, less ice, and other feedbacks. A doubling of CO2 concentrations would lead to about 3 °C warming. Timothy Osborn Professor, University of East Anglia, and Director of Research, Climatic Research Unit: Projections of future warming can’t be made from observations alone: we need understanding of the mechanisms and physical processes. Neither of these are provided by the quoted website, which instead contains inaccurate articles about supposed adjustments to temperature data and claiming a new ‘little ice age’ is already here—both of which have been shown to be incorrect by scientific research. (For example, section 1.3.2 of the Fourth Assessment Working Group I IPCC report compared global temperature records from various vintages and found broad consistency.) “The costs of emissions regulations, which will be paid by everyone, will be punishingly high and will provide no benefits to most people anywhere in the world.” Lauren Simkins Assistant Professor, University of Virginia: This is simply not accurate. Global warming is a global issue that, for example, affects global coastal populations, marine ecology, crop stability, and the area of habitable land. Humans, especially in countries with the largest carbon emissions, have been successfully altering the entire Earth system; therefore, climate change is currently the most global issue that we face and will continue to face in the coming centuries. Wolfgang Cramer Professor, Directeur de Recherche, Mediterranean Institute for Biodiversity and Ecology (IMBE): It is unclear what costs are referred to here. The regulations themselves cost nothing. The reductions of emissions will avoid huge damage costs and also produce economic benefits in other than the fossil-fuel dependent economic sectors. It is the damage costs that will be “paid by everyone”, not the emission reductions. 2. Continued CO2 emissions will not improve future crop production. The IPCC report concludes that the net result of further climate change will be to hinder global crop yields. “In 2013 the level of U.S. farm output was about 2.7 times its 1948 level, and productivity was growing at an average annual rate of 1.52%. From 2001 to 2013, world-wide, global output of total crop and livestock commodities was expanding at an average rate of 2.52% a year[…] Along with better plant varieties, cropping practices and fertilizer, CO2 has contributed to this welcome increase in productivity.” G Philip Robertson,Professor, Michigan State University: In general, CO2 has had a positive effect on crop growth, but it’s impossible to separate historical effects from the greater effects of genetics and nitrogen and other inputs. However, it’s generally considered to be a fraction of those. We know better future effects because we have CO2 fertilization experiments in the field comparing present to future CO2 levels. Those experiments suggest that corn may have about a 1% gain [because of increased CO2] and soybeans 3-4 times that. However, these gains will almost certainly be offset by yield declines associated with the temperature increases caused by elevated CO2, which are well known. Historically, it’s worth noting that we had elevated CO2 long before we had the green revolution, and crop yields didn’t increase much until the green revolution. You can see this in graphs of average US corn yields from 1900. Source: University of Nebraska-Lincoln “With more CO2 in the atmosphere, the challenge [feeding 2.5 billion more people] can and will be met.” Wolfgang Cramer Professor, Directeur de Recherche, Mediterranean Institute for Biodiversity and Ecology (IMBE): There is absolutely no scientific study that would support such a conclusion. And even if there was no climate effect of CO2, a simple speculative growth enhancement by CO2 could not produce such an effect. James Renwick Professor, Victoria University of Wellington: This is very naïve. Many factors control food production. If further large changes in climate come to pass, no amount of extra CO2 will improve food security. “Feeding these people and assuring them a comfortable living standard should be among our highest moral priorities.” Lauren Simkins Assistant Professor, University of Virginia: Climate change and poverty go hand in hand, as developing countries are disproportionately affected by climate change. “When someone says, ‘climate science is settled,’ remind them to check the facts.” James Renwick Professor, Victoria University of Wellington: The basic radiation physics has been well known for 150 years. The details will always be under discussion, but we are already seeing very clearly the expected patterns of climate change. Lauren Simkins Assistant Professor, University of Virginia: This statement highlights the major problem with this article. The authors do not support their claims with scientific references and data. Their logic is flawed and does not take into account basic scientific theories that explain, for example, the role of certain gases in causing a greenhouse effect and the negative impacts of high levels of greenhouse gases in the atmosphere. […] So based on this statement and the lack of scientific references in this article, readers should be prompted to disregard the majority of claims it presents."
https://science.feedback.org/review/sea-level-rise-accelerating-risk-associated-coastal-storm-surge-contrary-claim-forbes/,Inaccurate,"Forbes, Roy Spencer, 2016-10-25","Sea level rise, which was occurring long before humans could be blamed, has not accelerated.",,"Factually wrong: The evidence from records of past climate shows that the rate of sea level rise is greater now than it was before the Industrial Revolution.  Misleading: The rate of sea level rise is expected to increase as a result of ocean warming and melting glacial ice, so using the current rate to project the future risk of storm surge fails to account for what the risk really is.","Continuing warming causes an accelerating rise of sea level, impacting coastal regions in a variety of ways—including increasing the damage from storm surge events.","Sea level rise, which was occurring long before humans could be blamed, has not accelerated and still amounts to only 1 inch every ten years. If a major hurricane is approaching with a predicted storm surge of 10-14 feet, are you really going to worry about a sea level rise of 1 inch per decade?",,"Benjamin Horton Professor, Earth Observatory of Singapore: Proxy analysis has clearly shown an acceleration in rate of sea-level rise. Our research* found that the rate of sea-level rise on the US Atlantic coast is greater now than at any time in the past 2,000 years. The research also shows a consistent link between global mean surface temperature and changes in sea level for the past millennium. The study shows that after relatively subtle changes in temperature and sea-level rise over the last 2,000 years, the rate of sea-level rise increased in the late 19th century. Sea-level rise contributes significantly to the frequency of flooding from hurricanes. The contribution from sea-level rise to flood height works in together with other factors such as timing of the storm relative to high tide, and the strength and direction of individual hurricanes. Sea-level rise between hurricanes raises the “baseline” water level and makes flooding more likely. We published another paper* showing that New York City can expect nine-foot floods, as intense as that produced by 2012’s Superstorm Sandy, at least four times more frequently over the next century. We report that floods as intense as Sandy’s would have occurred about once every 400 years on average under present day sea-level rise conditions, but that over the 21st century are expected to be about four times more probable (once every 100 years) due to an acceleration in the rate of sea-level rise. Kemp et al. (2011)Climate related sea-level variations over the past two millennia, Proceedings of the National Academy of Sciences Lin et al. (2016)Hurricane Sandy’s flood frequency increasing from year 1800 to 2100, Proceedings of the National Academy of SciencesPeter Gleick President Emeritus and Chief Scientist, Pacific Institute: A major storm that has a sea-level higher than it would otherwise have been without climate change will simply be more damaging. It doesn’t matter that current sea-level rise changes are slow. Sandy’s storm surge hit at high tide—a tide that was higher than it would otherwise have been because of human-caused climate change. Some estimates are that damages were many billions of dollars higher as a result.Kerry Emanuel Professor of Atmospheric Science, MIT: Sea level rise is indeed accelerating and is currently tracking predictions that are consistent with a roughly 1 meter (3 foot) rise by the end of the century. We are already seeing bad effects in places like Miami Beach. And 1 meter makes a large difference, so if one is concerned about one’s descendants, then yes, it is something to worry about.Jim Kossin Research Scientist, NOAA's Center for Weather and Climate: Sea level rise and its impacts vary considerably by region. To state a global mean number is misleading and irrelevant to those regions that are most vulnerable. With or without hurricanes added to the mix, the impacts on humans from sea level rise can be seen now. The author’s comparison of hurricane storm surge to sea level rise is very misleading and blurs the relevance of sea level rise to humans. Sea level rise is creating nuisance flooding in a number of places. The fact that hurricane storm surge is bigger is irrelevant and does not change the fact that people are being impacted.Victor Venema Scientist, University of Bonn, Germany: Sea level rise started before we had good instrumental observations, which makes it harder to see the acceleration. If you look sea level rise for longer periods based on indirect (proxy) evidence, it is clear that the current sea level rise is much faster than it was during the last 1000 years. See for example this article on RealClimate on a recent study for the last 2000 years. It will depend on our actions whether sea level rise will accelerate much more. See this article on the expected sea level rise for the coming century. Figure – Past and future sea-level rise. For the past, proxy data are shown in light purple and tide gauge data in blue. For the future, the IPCC projections for very high emissions (red, RCP8.5 scenario) and very low emissions (blue, RCP2.6 scenario) are shown. Source: IPCC AR5 Fig. 13.27 https://www.sharethefacts.co/share/3583ab0c-6cbe-4171-bd7a-ab2925e29e22"
https://science.feedback.org/review/hillary-clinton-boards-climate-crisis-train-nowhere-roy-spencer-forbes/,-1.8,"Forbes, by Roy Spencer, on 2016-10-25.",,"""Hillary Clinton Boards The Climate Crisis Train To Nowhere""",,,,,"This commentary by Dr. Roy Spencer published in the opinion section of Forbes makes a number of inaccurate and misleading scientific claims. For instance the article claims that climate change would be so slow that “it cannot be observed by anyone in their lifetime”, which is demonstrably wrong. It also misrepresents the impacts of climate change and makes claims about sea level and temperature records that are not supported by the evidence. Note: This article was evaluated only for scientific accuracy—Climate Feedback does not endorse or oppose political opinions.See all the scientists’ annotations in context If the link does not work due to the landing page ads on Forbes, install the Hypothesis extension in your browser and switch it on from the article page.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Kerry Emanuel Professor of Atmospheric Science, MIT: The article is inaccurate in several places and conveys that one must choose between solving immediate problems, such as poverty, and long-term risks such as climate change. We can do both, and indeed must do both if we take poverty seriously, since climate change disproportionately affects the poor. Jim Kossin Research Scientist, NOAA's Center for Weather and Climate: The author makes a number of statements that are not supported by the science or by established scientific process. He is basically playing by a different set of rules than the scientific community at large, which allows him to say anything he wants in order to make his case. A number of statements are misleading and some are obfuscating, particularly in terms of potential impacts of climate change on humans. Victor Venema Scientist, University of Bonn, Germany: This article by Roy Spencer is misleading when it comes to his own work on tropospheric temperature changes and several times severely wrong outside of his expertise. It does not give a fair overview of the state of the science. Peter Gleick President Emeritus and Chief Scientist, Pacific Institute: Almost every claim in this article is scientifically inaccurate or misleading. Alexis Berg Research Associate, Harvard University: This articles uses a number of misleading statements, logical flaws and unsubstantiated claims to try to defend the erroneous idea that climate change is nothing to worry about, that there is nothing to do about it anyway, and that wanting to address it is all a power play by politicians. Benjamin Horton Professor, Earth Observatory of Singapore: The discussion on sea level rise is misleading. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from Roy Spencer; comments and replies are from the reviewers. 1.The influence of climate change on some types of extreme weather are still unclear (e.g. tornadoes), however the strongest hurricanes are expected to become even more intense as the climate continues to warm. “Global warming and climate change, even if it is 100% caused by humans, is so slow that it cannot be observed by anyone in their lifetime. Hurricanes, tornadoes, floods, droughts and other natural disasters have yet to show any obvious long-term change.” Jim Kossin Research Scientist, NOAA's Center for Weather and Climate: This statement is far too broad to be supportable, and is misleading in a few ways. Among the many aspects and impacts of climate change, some are evolving slowly and others more quickly (quickly enough to be detected within a 70-year human lifetime). There is a very important difference between saying “there has been no change”, versus “the data records are not long enough to formally detect a change”. For example, our present records of hurricanes do in fact show very large and statistically significant increasing trends in a number of measures since the 1800s. But we also know that the older data are of a lower quality than modern data, so we are uncertain of what part of the trends are due to the data issues and what part may be due to human influences. The scientific community has established a very strict set of rules for formally establishing whether or not a trend has been detected, and we constrain our statements within this rigid framework. The author’s statement here violates those rules and is unsupportable Alexis Berg Research Associate, Harvard University: As others have noted, this is flat out wrong. With barely 1C of global warming there are already changes in temperatures, humidity precipitation patterns, sea ice, land ice, sea level, vegetation, etc., that i) can be observed, and ii) can be attributed to human-made global warming. And certainly in the coming decades, that is, within our “lifetime”, further changes are going to be even more obvious. “Furthermore, the overall increases in such things as hurricanes and tornadoes have not materialized.” Jim Kossin Research Scientist, NOAA's Center for Weather and Climate: Again, this statement is not supported by the science. We are seeing changes. We just don’t have long enough data records to formally detect the changes and attribute them to human influence. The rules of detection and attribution are well established, strict, and conservative. The author’s statement here is outside of the rules and can’t be supported in any true formal scientific sense. […] It’s wrong and unsupportable to say that there have been no changes. Our theory of hurricanes and our best numerical models inform us that hurricanes will become stronger as the world warms, and that the increase will be most evident in the strongest hurricanes. These are the hurricanes that kill the most people and do the most damage. Furthermore, increases in strength or number are not the only ways that hurricanes can change. There is mounting evidence that tropical cyclones in various regions of the world are migrating poleward. This creates significant changes in hazard exposure and human mortality risk, even in the absence of any changes in strength. “Drought in the western U.S. pales in comparison to the mega-droughts tree rings tell us existed in centuries past.” Peter Gleick President Emeritus and Chief Scientist, Pacific Institute: There are many scientific papers, going back years now, that show the influence of climate changes on the western US droughts. The fact that there have been “mega-droughts” in the past is irrelevant to whether climate changes are now influencing current droughts. See: Swain et al. (2014) The Extraordinary California drought of 2013/2014: Character, Context, and the role of climate change, Bulletin of the American Meteorological Society Mann and Gleick (2015) Climate change and California drought in the 21st century, Proceedings of the National Academy of SciencesDaniel Swain Climate Scientist, University of California, Los Angeles: In Swain et al. (2014)*, we do find that global warming has increased the likelihood of one of the “ingredients” of the California drought—specifically, very high middle atmospheric pressures. A more direct reference might be Diffenbaugh et al. (2015)*, where we specifically quantify the degree to which human caused warming has increased the likelihood of drought in California. There are other papers, as well, that find at least a fractional contribution of warming to this event. I also agree with Peter Gleick’s remark that the existence of past droughts of large magnitude is largely irrelevant when seeking causes of the present one, and does not disprove a human role in modern droughts. Swain et al. (2014) The Extraordinary California Drought of 2013/2014: Character, Context, and the Role of Climate Change, Bulletin of the American Meteorological Society Diffenbaugh et al. (2015)Anthropogenic warming has increased drought risk in California, Proceedings of the National Academy of Sciences Alexis Berg Research Associate, Harvard University: Note the comparing reconstructions of past droughts with climate model projections suggests that “future drought risk will likely exceed even the driest centuries of the Medieval Climate Anomaly (1100–1300 CE) in both moderate (RCP 4.5) and high (RCP 8.5) future emissions scenarios, leading to unprecedented drought conditions during the last millennium”. See Cook et al. (2015) Unprecedented 21st century drought risk in the American Southwest and Central Plains, Sciences Advances. “Lake-bottom sediments in Florida tell us that recent major hurricane activity in the Gulf of Mexico has been less frequent than in centuries past.” Kerry Emanuel Professor of Atmospheric Science, MIT: The lake-bottom sediment study, in which I participated, catalogued hurricanes at a particular location over several thousand years. There are indeed centennial-scale variations at particular locations that are not strongly correlated across different locations, so the authors interpreted these fluctuations in terms of changing [hurricane] tracks. The technique cannot distinguish between a weak event nearby and a strong one at a distance, so there is little data pertaining to storm intensity. “It has now, even after Hurricane Matthew, been over 4,000 days since a major hurricane (Category 3 or stronger) has made landfall in the U.S.” Jim Kossin Research Scientist, NOAA's Center for Weather and Climate: The definition of US major hurricane landfall is strict but also arbitrary, and isn’t a particularly good measure of coastal risk. The threshold of a major hurricane, and the restriction that the center of a hurricane must move over land is somewhat ad hoc and may obfuscate the points of relevance. For example, many coastal communities have experienced major hurricane landfalls over the past 4,000 days. They just don’t happen to be within the geopolitical border of the contiguous US. Matthew is in fact a good example for why the author’s statement is misleading. Matthew did a great deal of damage as a major hurricane without technically having its center touch land. The fact that it didn’t make formal landfall as a major hurricane is not particularly relevant when considering coastal hazard exposure and human mortality risk. Kerry Emanuel Professor of Atmospheric Science, MIT: One can always cherry-pick a sufficiently narrow statistic, like major landfalling continental US hurricane, that will support one’s prejudice. The fact is that there has been no pause in ALL Atlantic basin or landfalling (including regions outside the US) storms. 2.Continuing warming causes an accelerating rise of sea level, impacting coastal regions in a variety of ways—including increasing the damage from storm surge events. “Sea level rise, which was occurring long before humans could be blamed, has not accelerated and still amounts to only 1 inch every ten years. If a major hurricane is approaching with a predicted storm surge of 10-14 feet, are you really going to worry about a sea level rise of 1 inch per decade?” Benjamin Horton Professor, Earth Observatory of Singapore: Proxy analysis has clearly shown an acceleration in rate of sea-level rise. Our research* found that the rate of sea-level rise on the US Atlantic coast is greater now than at any time in the past 2,000 years. The research also shows a consistent link between global mean surface temperature and changes in sea level for the past millennium. The study shows that after relatively subtle changes in temperature and sea-level rise over the last 2,000 years, the rate of sea-level rise increased in the late 19th century. Sea-level rise contributes significantly to the frequency of flooding from hurricanes. The contribution from sea-level rise to flood height works in together with other factors such as timing of the storm relative to high tide, and the strength and direction of individual hurricanes. Sea-level rise between hurricanes raises the “baseline” water level and makes flooding more likely. We published another paper* showing that New York City can expect nine-foot floods, as intense as that produced by 2012’s Superstorm Sandy, at least four times more frequently over the next century. We report that floods as intense as Sandy’s would have occurred about once every 400 years on average under present day sea-level rise conditions, but that over the 21st century are expected to be about four times more probable (once every 100 years) due to an acceleration in the rate of sea-level rise. Kemp et al. (2011)Climate related sea-level variations over the past two millennia, Proceedings of the National Academy of Sciences Lin et al. (2016)Hurricane Sandy’s flood frequency increasing from year 1800 to 2100, Proceedings of the National Academy of Sciences Peter Gleick President Emeritus and Chief Scientist, Pacific Institute: A major storm that has a sea-level higher than it would otherwise have been without climate change will simply be more damaging. It doesn’t matter that current sea-level rise changes are slow. Sandy’s storm surge hit at high tide—a tide that was higher than it would otherwise have been because of human-caused climate change. Some estimates are that damages were many billions of dollars higher as a result. Kerry Emanuel Professor of Atmospheric Science, MIT: Sea level rise is indeed accelerating and is currently tracking predictions that are consistent with a roughly 1 meter (3 foot) rise by the end of the century. We are already seeing bad effects in places like Miami Beach. And 1 meter makes a large difference, so if one is concerned about one’s descendants, then yes, it is something to worry about. Jim Kossin Research Scientist, NOAA's Center for Weather and Climate: Sea level rise and its impacts vary considerably by region. To state a global mean number is misleading and irrelevant to those regions that are most vulnerable. With or without hurricanes added to the mix, the impacts on humans from sea level rise can be seen now. The author’s comparison of hurricane storm surge to sea level rise is very misleading and blurs the relevance of sea level rise to humans. Sea level rise is creating nuisance flooding in a number of places. The fact that hurricane storm surge is bigger is irrelevant and does not change the fact that people are being impacted. Victor Venema Scientist, University of Bonn, Germany: Sea level rise started before we had good instrumental observations, which makes it harder to see the acceleration. If you look sea level rise for longer periods based on indirect (proxy) evidence, it is clear that the current sea level rise is much faster than it was during the last 1000 years. See for example this article on RealClimate on a recent study for the last 2000 years. It will depend on our actions whether sea level rise will accelerate much more. See this article on the expected sea level rise for the coming century. Figure – Past and future sea-level rise. For the past, proxy data are shown in light purple and tide gauge data in blue. For the future, the IPCC projections for very high emissions (red, RCP8.5 scenario) and very low emissions (blue, RCP2.6 scenario) are shown. Source: IPCC AR5 Fig. 13.27 “If Hillary would have fact-checked her example of sea level rise in Norfolk, Virginia, she would have found out that the experts already know this is mostly due to the land there sinking.” Benjamin Horton Professor, Earth Observatory of Singapore: Without global warming, global sea level would have risen by less than half the observed 20th century increase and might even have fallen. We published another paper in PNAS (Kopp et al., 2016*) that showed that with global warming global sea level rose by about 14 centimeters, or 5.5 inches, from 1900 to 2000. That is a substantial increase, especially for vulnerable, low-lying coastal areas. The sinking of land in Virginia is responsible for the slow sea-level rise from 3000 years ago to the beginning of the industrial revolution. The 20th century rise was extraordinary in the context of the last three millennia—and the rise over the last two decades has been even faster. The study’s global sea-level reconstruction calculated how temperatures relate to the rate of sea-level change. Based on this relationship, the study found that, without global warming, 20th century global sea-level change would very likely have been between a decrease of 3 centimeters (1.2 inches) and a rise of 7 centimeters (2.8 inches). A companion report finds that, without the global warming-induced component of sea-level rise, more than half of the 8,000 coastal nuisance floods observed at studied US tide gauge sites since 1950 would not have occurred. Kopp et al. (2016)Temperature-driven global sea-level variability in the Common Era, Proceedings of the National Academy of Sciences 3.If followed, the pledged greenhouse gas emissions reductions of the international Paris Agreement will significantly reduce future warming and its impacts. “[…]even if the countries of the world agree to do what they promised on climate change, […]the promised actions will have no measurable effect on future global temperatures.” Victor Venema Scientist, University of Bonn, Germany: The current promises of governments around the world (INDCs) are not enough to stay below a warming of 2 °C, but they do make a difference. In an article in Nature this June, Joeri Rogelj and colleagues: “The INDCs collectively lower greenhouse gas emissions compared to where current policies stand, but still imply a median warming of 2.6–3.1 degrees Celsius by 2100.” “[…]until we develop a practical, cost-competitive alternative to fossil fuels, it is unlikely that renewable energy will ever make up more than 15-20% of global energy requirements.” Celine Guivarch Senior researcher, CIRED, Ecole des Ponts: In many countries renewables are already competitive compared to fossil fuels, and represent a larger share than the 15-20% mentioned here. Costs of renewable are still falling. And the investment in renewable is accelerating. For instance, the IEA has revised its renewable forecasts upwards. Many scenarios and studies foresee that renewables could represent a much larger share than 15-20%. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: Dr. Spencer provides no evidence to back up his assertion that renewables are necessarily limited to 15%-20% of generation. Prices of renewable technologies have been falling rapidly over the past decade, with solar power alone falling 60% and wind falling 40%. In more and more parts of the world renewables are cost-competitive with traditional fossil fuels. And unlike traditional fuels, renewables are not mature technologies and likely have additional price reductions to come. In some areas additional storage might be needed to balance out high renewable penetration. Even here storage costs have fallen dramatically due to advances in battery technologies. Additionally, electric vehicles and natural gas both enable additional renewables through grid balancing. “And since the biggest risk to humanity is poverty, if we allow policymakers to have their way, the resulting energy poverty will indeed cause the deaths of some of our children and grandchildren.” Celine Guivarch Senior researcher, CIRED, Ecole des Ponts: Poverty and energy poverty are indeed a risk for humanity; but current understanding shows that unmitigated climate change would hinder the efforts of poverty alleviation, because climate change impacts bear on most vulnerable countries and people. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: There is no necessary tradeoff between fighting poverty and climate change. There are actually a number of co-benefits to a more sustainable development pathway. For example, outdoor air pollution driven largely by coal use currently kills well over a million people annually*, and represents one of the most urgent public health crises on the planet. Addressing it by transitioning from coal to renewables, nuclear, and natural gas could benefit both health and the environment in developing countries. Rohde (2015)Air Pollution in China: Mapping of Concentrations and Sources, PLOS ONE Note: Satellites have measured the Earth’s temperature for only about 30 years. When comparing models to observations, it is wise to include the wealth of longer-term measurements in order to avoid being mislead by short-term natural fluctuation. “But the observed warming as monitored by satellites (our only truly global monitoring system) has been only about half of what computerized climate models say should be happening.” Carl Mears Senior Research Scientist, Remote Sensing Systems (RSS): The statement is fairly accurate but leaves the inference of causes up to the reader. A recent paper by Santer et al. (2016)* investigated this issue in considerable detail. For middle tropospheric temperatures the paper found that, on average, models showed 1.71 times more warming than the mean of the most recent version of the satellite data for the 1979-2015 period. This is for near global mean temperatures. For the lower troposphere, the models show about 2 times more warming than the satellites. Note that the Remote Sensing Systems lower tropospheric dataset has not yet been upgraded to the latest version, which is likely to show more warming. The article does not discuss possible reasons for this discrepancy, but given the tone of the rest of the article, the reader is expected to use the trend differences as evidence that long-term projections by climate models are suspect. These ratios do not provide such evidence. At least part of the discrepancy is known to be caused by errors in the forcings used to drive the CMIP-5 climate models. After the year 2000, the CMIP-5 models were driven by forecast values for important parameters such as volcanic aerosols, solar output, and stratospheric ozone. The forecasts turned out to be slightly inaccurate, causing the models to predict more warming than they would have if the correct forcings had been used. (Of course, these correct forcings were in the future and thus unknowable at the time the model computations were performed). Other possible causes include natural variability in the real world (which might produce a period of reduced warming) and errors in the model physics. Only errors in the model physics would cause long-term global warming to be overestimated, and there is no significant evidence that supports large errors in the model physics. Over a much longer time period, 1880-present, the warming at the surface agrees well with that expected by the CMIP-5 models. The longer time period is important because the effects of random fluctuations due to natural variability tend to average away as the time period considered gets longer. Santer et al. (2016)Comparing tropospheric warming In climate models and satellite data, Journal of Climate"
https://science.feedback.org/review/sea-level-rise-those-non-disappearing-pacific-islands-bjorn-lomborg-wall-street-journal/,-1.2,"The Wall Street Journal, by Bjorn Lomborg, on 2016-10-13.",,"""About Those Non-Disappearing Pacific Islands""",,,,,"This Wall Street Journal article comments on the fact that atoll islands in the Pacific are not all simply shrinking as sea level rises, because dynamic coastal processes can move sediment to build shorelines outward. However, the article doesn’t mention that sea level rise related to unchecked global warming would ultimately make many low-lying islands in the Pacific uninhabitable. The author, Bjorn Lomborg, cherry-picks this specific piece of research and uses it in support of a broad argument against the value of climate policy. He also misrepresents the Paris Agreement to downplay its potential to curb future climate change. See all the scientists’ annotations in contextGUEST COMMENTS: Katrin Meissner Professor, University of New South Wales: This article is misleading. The dynamics of shorelines of low-lying Pacific Islands are complicated and influenced by many local factors. Climate change and associated sea-level change are the underlying trend that will “win” over long time scales. There are many wiggles and local anomalies that, if taken out of context and analysed over short timescales, might hide the overall trend. This article is a textbook example of cherry-picking–jumping to false conclusions based on a small sample of data that does not reflect the bigger picture. Paul Kench Professor, The University of Auckland: There are a lot of claims that islands are passive geological entities that will sit there and drown. Our work shows that they are anything but static. They are dynamic. They move around and they can grow. So just because sea level is rising, it doesn’t mean doom and gloom for all atolls. Although the islands may survive into the future, the changes could still affect issues like fresh water and agriculture, potentially making life on these islands much more difficult than it is today.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Stephan Lewandowsky Professor, University of Bristol: This article is very interesting because it exemplifies a highly-misleading rhetorical practice that is effective, frequently used, but not easily recognized by the public–and hence all the more damaging. This is known as “paltering” and the term was popularized by Frederick Schauer and Richard Zeckhauser in 2009 and refers to “fudging, twisting, shading, bending, stretching, slanting, exaggerating, distorting, whitewashing, and selective reporting.” A successful palterer will try to avoid being untruthful in each of his/her utterances, but will nonetheless put together a highly misleading picture based on selective reporting, half-truths, and errors of omission. As the commenters have pointed out, this is the case here. Unfortunately, paltering is difficult for non-experts to detect and the best defense against it is to know who engages in it and for what political purpose. Lauren Simkins Assistant Professor, University of Virginia: Land area gains due to sediment accretion in the Marshall Islands and other low-lying coastlines do not necessarily indicate that coastal populations are spared from the effects of sea-level rise. I find the presented argument that the focus should be on reducing poverty and political corruption in the Marshall Islands rather than on cutting global carbon emissions not well supported and misleading to a general audience. Alexis Berg Research Associate, Harvard University: The article contains a number of logical fallacies – red herring, false dichotomy – that seem to be recurrent in Lomborg’s articles. He does point out an interesting and perhaps little-known fact about current land dynamics of Pacific atoll islands; however, this fact, in and of itself, does not all of a sudden make current concern about global climate change overblown and irrelevant, as the article somehow implies. His presentation of the Paris Agreement and discussion of the best strategy to address global warming is, in my view, dishonest and misleading. Daniel Kammen Professor, University of California, Berkeley: In my view the author attempts to develop a polemic that funds spent on climate change are not benefiting the poor, and that there is, in fact, a choice between one and the other. This is demonstrably false, and yet the author repeats it despite the evidence. James Renwick Professor, Victoria University of Wellington: The effects of sea level rise on tropical Pacific islands are indeed complicated. Implying that climate change and sea level rise are therefore not urgent concerns is very misleading. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from Bjorn Lomborg; comments and replies are from the reviewers. 1. Sea level rise does not simply result in reduction of island area as other dynamic processes shape their coasts, but in the long term it would make low-lying islands uninhabitable. “Research shows that this process is overpowering the erosion from sea-level rise, leading to net land-area gain. This is not only true for the Marshall Islands. […]several studies have documented noteworthy shoreline progradation [growth] and positional changes of islands since the mid-20th century, resulting in a net increase in island area.” James Renwick Professor, Victoria University of Wellington: The dynamics of sand accretion and loss across the tropical Pacific is indeed complicated, and many atolls are at the moment growing. However, as sea levels rise in this area of the globe, water tables also rise and become salinated, reducing the availability of fresh water for drinking or agriculture. Focusing on the tropical Pacific takes attention away from regions where the signal is much clearer, e.g. the east coast of the USA. The occurrence of “nuisance flooding” and coastal inundation has risen dramatically in recent decades. Another 50-100 centimeters of sea level rise globally threatens vast swaths of built infrastructure and hundreds of millions of lives. Whether or not Pacific atolls accrete or shrink is not the most central issue. Katrin Meissner Professor, University of New South Wales: This statement is oversimplified and cannot be generalised. For example, there is evidence from the Solomon Islands that five islands have disappeared in recent years while six others have experienced severe shoreline recession*. This evidence is based on time series of aerial and satellite imagery from 1947 to 2014 of 33 islands, along with historical insight from local knowledge: “Shoreline recession at two sites has destroyed villages that have existed since at least 1935, leading to community relocations…” Albert S et al (2016) Interactions between sea-level rise and wave exposure on reef island dynamics in the Solomon Islands Environmental Research Letters Lauren Simkins Assistant Professor, University of Virginia: As wave energy and rising sea levels batter coastlines, the erosional products (i.e. sediments) can either be accreted onto the existing land or removed offshore into the deep ocean. Where the sediment is redistributed depends on a number of factors. Although sediment accretion can increase land area, it does little to change the elevation of low-lying islands, like the Marshall Islands. Therefore, people living in low-lying areas, even if there is historical land area gain, are still susceptible to inundation and damages due to storm waves, higher-than-usual tides (e.g. king tides), and sea level rise. These unconsolidated, loose sediments are also easily mobilized; therefore, localized land area gains by sediment accretion can be very dynamic on short timescales. This article could leave readers thinking that land area gains alone can mitigate the effects of sea level rise on low-lying coastal areas, but land elevation is what is really important. “The most famous of these studies, published in 2010 by Paul Kench and Arthur Webb of the South Pacific Applied Geoscience Commission in Fiji, showed that of 27 Pacific islands, 14% lost area. Yet 43% gained area, with the rest remaining stable.” Paul Kench Professor, The University of Auckland: This comment does provide a reasonable assessment of the message of our article: that the majority of islands have become larger or remained stable and that islands are locationally dynamic on their reef platforms. We think these dynamic features do pose management challenges for island communities. However, all reports fail to reflect the nuances of our work. Arthur Webb Coastal geomorphologist, The University of Wollongong: What is for sure is that the island’s natural sedimentary systems will not just sit and be unresponsive. The islands will respond but we must be very careful to point out that ”response” does not necessarily mean that the islands will be maintained in the form we recognize today, that is, we do not know how long an island with soils for agriculture, complex vegetation, good fresh groundwater reserves, etc. can be maintained. Indeed, given what we understand of increasing rates of sea level rise we may be talking about relatively inhospitable gravel banks as the response to the next 100 years of sea level rise. “It seems self-evident that rising sea levels will reduce land area. However, there is a process of accretion, where coral broken up by the waves washes up on these low-lying islands as sand, counteracting the reduction in land mass. Research shows that this process is overpowering the erosion from sea-level rise, leading to net land-area gain.” Arthur Webb Coastal geomorphologist, The University of Wollongong: It’s just plain wrong to assume that all atolls are washing away. It’s also wrong to sugar-coat the sobering facts that rising sea levels will ultimately seal the fate of low-lying islands and their limited soils and groundwater. The confusion isn’t surprising. It’s just more complicated than many expect. 2. The author reaches his conclusion by relying on flawed reasoning: for instance he cherry-picks studies and ignores the “big picture”, in contradiction to what he recommends. “suggest that residents are fleeing atolls swiftly sinking into the sea. Yet new research shows that this is not the entire—or even an accurate—picture.”Emmanuel M Vincent Research Scientist, University of California, Merced: Scientists’ comments on this article clearly show that it is also not an “entire” or “accurate” picture. So Mr. Lomborg is using the very flawed reasoning he is condemning others of. “Representatives from the Marshall Islands have been vocal about the need for strong global action on climate. President Hilda Heine has told reporters that longtime residents are leaving the Marshall Islands because climate change is threatening the nation’s existence.” Daniel Kammen Professor, University of California, Berkeley: Mr. Lomborg cherry-picks studies relative to the global average. (Indeed, some areas of the Canadian Maritimes and Greenland are expected to see sea-level fall, but overall the rise is significant and a huge danger to the poor). The idea that aiding the poor was an alternate to addressing climate change was wrong 15 years ago when I last debated Mr. Lomborg and is wrong today. False dichotomies are a sad refuge from the facts of both poverty and climate change. Emmanuel M Vincent Research Scientist, University of California, Merced: This is an interesting rhetorical trick by Bjorn Lomborg. So far he has only supported the point that ‘as of today, the area of many Pacific islands have not decreased’. But this doesn’t mean that ‘the islands existence is not threatened’, notably in the future as sea level rise becomes more severe. So here, he is swapping a weak claim that he has supported for a much stronger one that he has not, a version of the red herring fallacy. “Those who seek to help should keep the bigger picture in mind.” James Renwick Professor, Victoria University of Wellington: Exactly Mr Lomborg. That’s why focusing on a small component of the story, in an area where many competing forces mask the underlying signal, is such a narrow approach. If one looks at the big picture of climate change, the loss of ice and snow, the increasing high temperature extremes, the already-apparent effects of sea level rise around the globe, the urgency of the problem becomes crystal-clear. “Policy makers who want to help the residents of the Marshall Islands today should look at improving the islands’ resilience” Alexis Berg Research Associate, Harvard University: This is a classic technique in Lomborg’s articles: he focuses on one small aspect of climate change – here the Marshall Islands, other times maybe polar bears or heat-related human deaths – that i) he passes off as the main concern about global warming, and ii) that he can provide some seemingly contradictory information about… All the other consequences of global warming are conveniently set aside… Red herring. 3. Reducing greenhouse gas emissions to meet Paris Agreement pledges will cost money, but will also have a significant impact on the severity of global warming this century, contrary to Lomborg’s claim. “This will achieve almost nothing. My peer-reviewed research, published last November in the journal Global Policy, shows that even if every nation were to fulfill all their carbon-cutting promises by 2030 and stick to them all the way through the century—at a cost of more than $100 trillion in lost GDP—global temperature rise would be reduced by a tiny 0.3°F (0.17°C).”John Sterman Professor, Massachusetts Institute of Technology: Dr. Lomborg sets out to show that the INDCs [emission reduction pledges] are useless. To do so he grossly misrepresents the pledges. He constructs an incomplete accounting that omits the pledges of many nations, ignores China’s pledge to cap its emissions by 2030, and assumes that the [European Union countries] will abandon their commitment to emissions reductions as soon as their pledges are fulfilled. (find more details in this rebuttal of Lomborg’s paper) James Renwick Professor, Victoria University of Wellington: The last IPCC report makes it very clear that following a path of strong emissions reductions can indeed cap warming at 2C or less, while business as usual would see 4-5C of warming this century. It is also now clear that meeting the Paris targets will likely save the West Antarctic ice sheet from melting, while other scenarios would see many metres of sea level rise, effectively destroying many of the major cities of the world. The costs of such inaction are almost incalculable. “At a cost of between $1 trillion and $2 trillion annually, the Paris climate agreement, recently ratified by China, is likely to be history’s most expensive treaty. It will slow the world’s economic growth to force a shift to inefficient green energy sources.” Alexis Berg Research Associate, Harvard University: Not sure how these costs are derived—references would be good. […] These treaty costs may appear unprecedented, but so are the risks posed by climate change. Climate change “costs” are hard to quantify precisely – for instance, how to give a monetary value to the loss of certain ecosystems?—but likely to be quite significant. This recent study in Nature, for instance, indicates that: “If future adaptation mimics past adaptation, unmitigated warming is expected to reshape the global economy by reducing average global incomes roughly 23% by 2100 and widening global income inequality, relative to scenarios without climate change”. Burke et al (2015) Global non-linear effect of temperature on economic production. Nature Gary Yohe Professor of Economics and Environmental Studies, Wesleyan University: There are hundreds of corporations who have signed on to reducing emissions in their own best interest (e.g. Walmart, DuPont, Chevron, Johnson and Johnson, Mercedes Benz, Dow… consult the White House website for an expanded list), reducing emissions and helping their customers do the same, for the benefit of their bottom line and their employees and their shareholders. These companies know that they will make money working to reduce their carbon emissions (being first to get there). Their gains are not recognized by Bjorn’s cost estimates. This is not to say that it is free. It is to say that Bjorn’s Holy Grail of cost-benefit analysis should include the enormous deductions to costs from the market."
https://science.feedback.org/review/james-lovelock-interview-by-end-of-century-robots-will-have-taken-over-decca-aitkenhead-the-guardian/,-1.4,"The Guardian, by Decca Aitkenhead, James Lovelock, on 2016-09-30.",,"""James Lovelock: ‘Before the end this century, robots will have taken over’""",,,,,"The Guardian interviewed James Lovelock (who is promoting a new book) about his speculations on Earth’s future. While the article largely features Lovelock’s subjective opinions about the future, it also contains statements about climate science and climate change that reviewers find inaccurate and unsupported by current science. The article does not inform the reader when Lovelock’s opinions and extraordinary claims are at odds with the conclusions of science that are based on a wealth of empirical data.See all the scientists’ annotations in contextGUEST COMMENTS: Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: It is hard to evaluate this article, as it’s an interview rather than any specific statement of fact by the author. However, the interviewee James Lovelock makes a number of misleading, unsupported, or outright incorrect statements about climate science which largely go unchallenged. While the article presumably faithfully reports Lovelock’s opinions, when those opinions are couched as scientific statements more pushback (or at least nuance) might be warranted.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. James Renwick Professor, Victoria University of Wellington: Some interesting ideas, but this is largely a flight of fancy, not grounded in the science of climate change. Aimée Slangen Researcher, Royal Netherlands Institute for Sea Research (NIOZ): The quotes on climate change (e.g. sea-level rise, CO2 emissions) do not reflect the current state of the scientific literature at all. Ken Caldeira Senior Scientist, Carnegie Institution for Science: Jim Lovelock is a creative and original thinker who has had many great ideas and who has made many important contributions over his career. Creative people have great ideas by having many ideas and then filtering out the ideas that are not so great. Many very creative people are better at the idea generation stage than the idea filtering stage. The journalist did not balance Lovelock’s statements with a set of clear statements saying that the vast majority of informed climate scientists (as, for example, represented by the IPCC reports) have reached consensus on conclusions that are diametrically opposed to what Lovelock is saying, and that the IPCC scientists have backed up their statements with a wealth of empirical data, whereas Lovelock is largely opining without providing any substantive evidence to support his rather extraordinary claims. Extraordinary claims demand extraordinary evidence, and Lovelock has not even come up to the standards of providing what the scientific community would consider to be ordinary evidence. Lauren Simkins Assistant Professor, University of Virginia: Inaccuracies and a lack of reference to scientific findings result in an article that is purely opinion-based and extremely misleading. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from James Lovelock; comments and replies are from the reviewers. 1.Climate models used by scientists have overall accurately projected the change of climate observed over the past 20 years, notably regarding global temperature and CO2 concentration. ” ‘CO2 is going up, but nowhere near as fast as they thought it would. The computer models just weren’t reliable.’ ” Ken Caldeira Senior Scientist, Carnegie Institution for Science: This statement is just plain wrong. Atmospheric CO2 content has recently surpassed 400 ppm and this rate of increase is in line with model projections. Aimée Slangen Researcher, Royal Netherlands Institute for Sea Research (NIOZ): This graph from the IPCC’s Summary: For Policymakers shows that CO2 is actually at the medium to higher end of the projected changes:Figure: Global mean surface temperature as a function of cumulative total global CO2 emissions from multi-model results for various emissions scenarios (coloured lines) and observations (black line). Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: Lovelock seems rather confused on this point. CO2 has actually gone up a bit faster than the Intergovernmental Panel on Climate Change (IPCC) predicted back in the Fourth Assessment Report: But modeling CO2 concentrations isn’t really that complicated (at least in the short term), and not a big focus of the IPCC and climate modelers. Rather, they use a number of different future emission scenarios reflecting different paths society could take to estimate the future warming, sea level rise, precipitation changes, and other more complex emergent properties of the climate system. Lovelock seems to be mixing up CO2 concentrations with temperatures, but even temperatures have been well within the range projected by models. ” ‘Anyone who tries to predict more than five to 10 years is a bit of an idiot, because so many things can change unexpectedly.’ ” Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: Actually, scientists have a reasonably good track record at predicting changes to the Earth’s climate so far. For example, in 1981 NASA scientist James Hansen and colleagues predicted that continuing CO2 emissions would warm the earth 0.4 °C by 2010. In reality, 2010 temperatures were about 0.5 °C warmer than in the early 1980s. Similarly, our climate models generally do a good job of reproducing the range of temperature change (and variability) seen in observational data: ” ‘and it’s only got to take one sizable volcano to erupt and all the models, everything else, is right off the board’ ” Aimée Slangen Researcher, Royal Netherlands Institute for Sea Research (NIOZ): Volcanic eruptions do have a cooling effect, but the effect is temporary (the aerosol has a lifetime of about a year, with a recovery period of up to a decade), so you’d need a Pinatubo to go off every couple of years (which is not too likely to happen) and that would still not be enough to counteract the climate response to the increase in CO2 emissions. There is a lot of literature looking at the effect of volcanic eruptions in climate models*, whichshows the impact on sea-level rise, which is a small temporary sea-level fall, followed by a recovery over a decade or so. Gleckler et al (2006) Krakatoa lives: The effect of volcanic eruptions on ocean heat content and thermal expansion, Geophysical Research Letters Gregory (2010) Long‐term effect of volcanic forcing on ocean heat content, Geophysical Research LettersZeke Hausfather Director of Climate and Energy, The Breakthrough Institute: Volcanoes have a sizable impact on the climate, but a relatively short-lived one. The impact of a large volcano like the Pinatubo eruption in 1991 will cool the climate for a few years, but after five years or so the system would revert to nearly the same state it would have been without the eruption*. It would take a supervolcano or a large period of extended volcanism to seriously disrupt our modeled scenarios, and these sort of events are relatively rare (the odds of them happening in the next 100 years are very small). Some climate models do actually have volcanoes of various sizes stuck in randomly in the future (since we can’t really predict future volcanism apart from assuming it occurs at roughly the same rate as we’ve experienced in the past), but the inclusion of these don’t really change the expected warming or other climate impacts in the next century. Hansen et al (1996) A Pinatubo Climate Modeling InvestigationJames Renwick Professor, Victoria University of Wellington: This is completely untrue. In terms of CO2 emissions, all the volcanic eruptions in the world combined put less than 1% of human CO2 emissions into the atmosphere every year. A large volcanic eruption in the tropics can cool the climate significantly for a couple of years (such as Mt Pinatubo in 1991) but climate models capture this extremely well. 2. There are a variety of energy technologies that could help reduce greenhouse gas emissions, and each has strengths and weaknesses. “Even more heretical than his enthusiasm for fracking is Lovelock’s passionate support for nuclear power.” Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: Here Lovelock is less heretical than he thinks; most future energy scenarios that meet aggressive climate goals show an expansion of nuclear energy, particularly in countries like China. There is something of an open question whether Nuclear will remain cost-competitive with other near-zero carbon technologies, however, given how quickly the costs of these technologies have fallen: Source: energy.gov ” ‘Let’s see … I think uranium that is affordable to extract would last about 50 years, something in that range. It might be 100. When you’ve used all that up, you go to thorium, and that would last you three times as long as uranium—so, shall we say, about 200 years?’” Ken Caldeira Senior Scientist, Carnegie Institution for Science: It is true that conventional uranium resources are insufficient to power civilization for the long-term. However, innovative approaches are making uranium extraction from seawater look increasingly attractive economically. Cost-effective uranium extraction from seawater could power civilization for a very long time. That said, the Sun will also last a very long time, so solar power also makes a lot of sense, especially if we could develop good energy storage or global-scale electricity grids that could wheel power to the night side of the Earth. ” ‘You see, gas in America is incredibly cheap, because of fracking,’ he says. But what about the risk of triggering earthquakes? He rolls his eyes.” Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: Lovelock is correct that hydraulic fracturing has played a large role in driving down U.S. natural gas prices. He also states a reasonable position that some of the opposition to “fracking” has been based on scientifically-dubious claims. That said, there are certainly best practices that the industry could apply to minimize drinking water contamination as well as seismic activity (which is primarily associated with wastewater disposal wells rather than fracturing per se). Where fracking gets more complicated is in its climate impact. While we are very likely better off if we are replacing coal with gas, it’s hard to make the case that a large buildup of gas infrastructure is consistent with meeting our aggressive climate goals, at least in developed countries like the United States. For more details, see this recent Yale Climate Connections article. Lauren Simkins Assistant Professor, University of Virginia: There is a big misconception about the trigger of recent earthquakes in Oklahoma. Fracking in the United States has been used for several decades. However, the disposal of waste water into the subsurface has been directly linked to the recent earthquakes in Oklahoma. A quick google scholar search on “Oklahoma earthquakes”will bring up numerous articles that demonstrate this point. My family has lived in Oklahoma for decades and I can tell you first-hand that the increase in number of >3.0 magnitude earthquakes is unprecedented in the past 8 years. 3. The article contains some exaggerated assertions, as well as imaginative speculation about the future of human civilization—some of which simply reflects the author’s opinion and is at odds with scientific results that are based on evidence and data. ” ‘You’ve only got to look at Singapore. It’s two-and-a-half times higher than the worst-case scenario for climate change, and it’s one of the most desirable cities in the world to live in.’” Aimée Slangen Researcher, Royal Netherlands Institute for Sea Research (NIOZ): There is a study by Cannaby and colleagues from the UK Met Office on sea-level rise around Singapore*. They talk about vulnerable regions within 2 m of the sea level, and find a ‘worst-case’ sea-level rise of 0.74 ± 0.29 m by 2100, so I’d say this statement is not correct. Cannaby et al (2016) Projected sea level rise and changes in extreme storm surge and wave events during the 21st century in the region of Singapore, Ocean ScienceKen Caldeira Senior Scientist, Carnegie Institution for Science: I am not sure I understand Lovelock’s point about Singapore. Singapore is a relatively wealthy, urbanized country, with an economy that is not highly weather dependent. One would expect Singapore to be able to adapt to temperature changes with far greater ease than would a poor agrarian economy. Also, several studies have projected massive increases in sea-level as a consequence of climate change. Most of Singapore is within 15 meters of sea-level. Thus, if CO2 emissions continue, we can expect most of Singapore to be underwater within a few centuries. Lauren Simkins Assistant Professor, University of Virginia: Desirability of a location has nothing to do with how safe it is from the effects of climate change. “His Gaia hypothesis, which contends that the earth is a single, self-regulating organism, is now accepted as the founding principle of most climate science […]” James Renwick Professor, Victoria University of Wellington: This is going a bit far. The Gaia gave many scientists food for thought, and a new way of thinking about the climate system in a holistic way, but it is hardly the “founding principle” of most climate science. That remains the physics of fluid flow and heat transport, plus chemistry and biology, etc. Lauren Simkins Assistant Professor, University of Virginia: Climate science is based on physical, biological, and chemical processes. There are feedbacks between these processes such as biological consumption of atmospheric CO2 by photosynthesis. However, the idea of a self-regulated Earth system due to biological activity is not a common principle of climate science. “Before the end of this century, 80% of the world’s population would be wiped out.” Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: The late Stephen Schneider, one of the giants of modern climate science, once said that in his opinion “the ‘end of the world’ and ‘good for you’ are the two lowest probability outcomes” when discussing climate change. Lovelock seems to be swapping from one extreme largely unsupported by the bulk of existing scientific evidence to the opposite. In reality, our best evidence suggests that unmitigated climate change would be very detrimental to society (and the natural world), but that we can address it through difficult concerted action. The worst potential outcomes of climate change occur in scenarios where CO2 triples relative to pre-industrial levels, and while we still have a long way to go, the actions that countries around the world committed to in Paris will help avoid some of the most disastrous outcomes. ” ‘Well, [the green movement is] a religion, really, you see. It’s totally unscientific.’ ” Lauren Simkins Assistant Professor, University of Virginia: The ability of greenhouse gases to trap heat in the atmosphere, the fact that loss of ice decreases how much energy is reflected from Earth’s surface back to space, and ocean acidification due to uptake of CO2 into the ocean are all scientifically explained by chemical and physical processes. I am sure there are different definitions of “the green movement”, but any action that “the green movement” can advocate for reduced greenhouse gas emissions has the potential to alter the physical, chemical, and biological processes that cause warming."
https://science.feedback.org/review/climate-exaggeration-backfiring-robert-bradley-jr-forbes/,-1.7,"Forbes, by Robert Bradley Jr., on 2016-09-23.",,"""Climate Exaggeration is Backfiring""",,,,,"While inaccurate climate alarmism should certainly be avoided, this Forbes’ article fails to demonstrate that climate science has been alarmist. According to the scientists that reviewed this article, the piece relies on false assertions, misleading representations of science and scientists, and poor sources. Because the climate system responds somewhat slowly, the extent of future impacts depends critically on current greenhouse gas emissions, which can commit us to long-lasting changes. The author fails to grasp this point when he asserts that the worst impacts of climate change should have already occurred if they were realistic. The net economic costs of climate change are likely to be significant and to increase over time. However, attempts to measure climate change economic impacts at the global scale is highly dependent on economists’ assumptions and there are a hosts of climate change impacts that cannot be accounted for by consumption-based global aggregations of economic impacts (e.g. impacts on ecosystems, more pronounced impact on developing countries…).See all the scientists’ annotations in context REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Victor Venema Scientist, University of Bonn, Germany: This picking of quotes that are convenient for Robert Bradley Jr.’s narrative while ignoring what most climate scientists say is one of the most used rhetorical tools of this piece. The other is the use of offensive emotional language to reduce the critical thinking of his readers. People should know that Forbes is nowadays just a blogging platform. Britta Voss Postdoctoral Research fellow, U.S. Geological Survey: This article contains no serious evidence to support its claims that climate science is fraudulent and climate action is pointless. All of the sources it cites either do not truly support the claims or are not valid in themselves. It provides very little information of any sort, and is mostly a collection of debunked theories, cherry-picked references to actual science, and unsubstantiated mantras. Kyle Armour Assistant Professor, University of Washington: There is very little substance to evaluate here. Yes, one can find examples of when individual scientists or politicians have exaggerated the impacts of climate change. But to present those examples as if they are mainstream views, when they are not, is very misleading. Frank Vöhringer Dr. rer. pol, Scientist, Ecole Polytechnique Fédérale de Lausanne (EPFL): The article is a polemic with many derogatory and misleading statements. Overall, it’s a piece of disinformation. The pro-fossil-fuel bias becomes most apparent at the end of the article. Jeremy Fyke Postdoctoral researcher, Los Alamos National Laboratory: On the whole, this article is not an objective critique of climate science. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from Robert Bradley Jr.; comments and replies are from the reviewers. 1. Natural variability in Earth’s climate system drives year-to-year fluctuations but the underlying long-term warming trend driven by human activities is clear. “The discrepancy between model-predicted warming and (lower) real-world observations has inspired new respect for natural climate variability relative to greenhouse-gas forcing.” Victor Venema Scientist, University of Bonn, Germany: Robert Bradley Jr. probably makes the typical mistake of equating the spread of individual model simulations within the ensemble spread with the model uncertainty. If climate models are used for decadal climate prediction, like Robert Bradley Jr. does here, the uncertainty is twice as large as the model spread. (more details and explanations) Natural variability has been studied by science since the beginning. That El Niño fluctuations can give the appearance of a “hiatus” is something scientists have warned about since the likes of Robert Bradley Jr. have started their “hiatus” meme, ignoring all those warnings. Without any need for statistical expertise, this can be seen in the plot below from the Texas State Climatologist. Source “‘Although some researchers doubted the existence of a global warming hiatus because of coverage bias, artificial inconsistency, and a change point analysis of instrumental Ts records,’ a just-published study at Nature.com’s Scientific Reports found, ‘it is now accepted that a recent warming deceleration can be clearly observed.’” Jeremy Fyke Postdoctoral researcher, Los Alamos National Laboratory: …which has been truncated by several years of record temperatures increases—on top of previous record warmth. This is the superposition of a forced trend on top of natural variability. The cherry-picking of time series to prove that the Earth isn’t warming due to anthropogenic influence is a classic climate change contrarian tactic. Emmanuel M Vincent Research Scientist, University of California, Merced: This graph of global temperature helps to put the “slowdown” of warming that occurred around the 2000-2010 period in perspective. It is misleading to put the emphasis on the slowdown without reminding that, over the long term, the temperature keeps rising. Source: NOAA Britta Voss Postdoctoral Research fellow, U.S. Geological Survey: This article in Scientific American provides context left out by the author on the scientific debate over the warming “hiatus.” By cherry-picking only this line from a single study, the author misrepresents the painstaking process of data analysis and hypothesis testing that led to that conclusion. As the Scientific American article points out, the authors of the study cited by the author were confident in reporting their findings—which do not refute the existence of anthropogenic global warming—because science exists to challenge previous work and is constantly incorporating new information that may alter previous conclusions, a fact which undercuts the author’s claims repeated throughout his article that climate science is a politically-motivated house of cards. 2. While impacts of climate change are already occurring, much greater impacts are expected to build in the future as a consequence of current and future greenhouse gas emissions. “Back in the late 1980s, the UN claimed that if global warming were not checked by 2000, rising sea levels would wash entire counties away.” Britta Voss Postdoctoral Research fellow, U.S. Geological Survey: Rising seas are, in fact, forcing many Pacific island nations and coastal communities in the United States to plan for permanent evacuation. Although low-lying areas will not “disappear” into the ocean anytime soon, nuisance flooding, erosion, and storm surges are making maintaining these communities economically untenable. “In 2009, then-British Prime Minister Gordon Brown predicted that the world had only 50 days to save the planet from global warming. But fifty days and years later, and the earth still spins.” Britta Voss Postdoctoral Research fellow, U.S. Geological Survey: This is extremely misleading. The article this claim refers to reports that Gordon Brown stated that the 2009 Copenhagen Climate negotiators had 50 days to adopt an adequate agreement to prevent catastrophic climate change. The time span of 50 days is inaccurately used by the author here to suggest that Brown thought the world—rather than the negotiations—would end in 50 days. “…scientist James Hansen unequivocally stated: ‘We have at most ten years—not ten years to decide upon action, but ten years to alter fundamentally the trajectory of global greenhouse emissions.'” Victor Venema Scientist, University of Bonn, Germany: The classic because-x-did-not-happen-yet-thus-x-will-not-happen fallacy. A fallacy that is especially ignorant in the case of a problem like climate change which responds slowly, like an oil tanker… “Time is up on Gore’s ‘point of no return’ and Hansen’s ‘critical tipping point.’ But the two fathers of the global-warming movement (Hansen and Gore got it going back in the summer of 1988) have nary admitted their exaggeration nor set a new timetable for effective action.” Mike MacCracken Chief Scientist for Climate Change Programs, Climate Institute: Bradley indicates no understanding of the time it will take to change over the global fossil-fuel energy system and the inertia of the climate system. Observations are already showing that the accelerating loss of ice from the Greenland and Antarctic ice sheets is giving indications of committing the world to a few meters (roughly 5-10 feet) of rise in global sea level over the next few centuries, which would seriously disrupt many coastal cities and swamp a number of island nations—and there is no indication that actions to reduce emissions can reverse this commitment—so, we are indeed moving past the point where emissions cutbacks can keep sea level and climatic conditions near to the conditions that have allowed civilization to flourish over the past several centuries 3. The weight of evidence indicates that climate change presents a serious risk to societies around the world. “Sensitivity estimates—defined as the temperature effect from the enhanced greenhouse effect—have been coming down in the peer-reviewed literature…” Kyle Armour Assistant Professor, University of Washington: This statement is somewhat misleading. Estimates of equilibrium climate sensitivity have been coming down in one branch of the literature that uses global energy budget observations (e.g. Otto et al 2013). However, recent work suggests that those energy budget estimates are biased low, moving estimates back up again once those biases are corrected for (see my recent commentary*). Meanwhile, estimates of sensitivity from other methods (e.g., paleoclimate, process-based observational constraints or climate model simulations) haven’t budged. Altogether, I don’t see any reason that the IPCC range isn’t still our best guess. Kyle C. Armour (2016) Projection and prediction: Climate sensitivity on the rise, Nature Climate Change “climate economists see a positive externality, not a negative one, from the human influence on climate. (In technical lingo, the so-called social cost of carbon would be negative.)” Gary Yohe Professor of Economics and Environmental Studies, Wesleyan University: This is cherry-picking at its worst. You can always find an economist who will make enough assumptions so that he or she can give you the answer you want. In this case (references the social cost of carbon), you can get a benefit ONLY if you assume a very high discount rate (like 5% so that future generations do not matter), and you ignore equity issues, and you assume that warmer climates in the crop-intensive areas will not include an increase in the intensity and/or frequency of intense weather (drought, floods, etc….), and you do not recognize that warmer temperatures mean more pests and more weeds. see the Summary: for Policymakers of the Report of Working Group II to the fourth assessment of the IPCC Richard Tol Professor of Economics, University of Sussex: The social cost of carbon would indeed be negative for a low climate sensitivity. This is because the net impacts of climate change only turn negative at more pronounced warming, and this would occur in a more distant future for a low climate sensitivity. At the same time, the positive impacts of carbon dioxide fertilization would be unaffected. Mike MacCracken Chief Scientist for Climate Change Programs, Climate Institute: The present calculations of the “social cost of carbon” tend to be bottom up and so include only those costs that one can reasonably quantify. As a result many types of impacts are simply left out of the calculation, like the cost of losing the culture of an island nation that is swamped, the impacts of ocean acidification and biodiversity loss, the actual social cost of climate change (e.g., of the New England climate becoming that of the Southeast, Sweden like Spain, etc.)… Britta Voss Postdoctoral Research fellow, U.S. Geological Survey: At a minimum, the author should be honest and say that “some climate economists” conclude that the net externalities of climate change may be positive, as the article he links to discusses only the economic views of its author and anecdotes from two climate scientists. Further, the article the author links to discusses only the net economic impacts on “the US and most of the developed countries”, while climate change will impact economies around the globe. This is not a meaningful argument anyway, as the exact value of the climate sensitivity does not inherently determine whether climate impacts will be economically net positive or negative. Frank Vöhringer Dr. rer. pol, Scientist, Ecole Polytechnique Fédérale de Lausanne (EPFL): There are positive and negative economic consequences of climate change. On a global level and for average temperature increases of more than 2 degrees Celsius, most climate economists find a negative influence of climate change on human welfare (and even more clearly on ecosystems), although negative net damages have been calculated in some instances. Net damages tend to be more pronounced in tropical countries, which usually have lower per capita incomes. For this reason, purely consumption-based global aggregations of climate impacts tend to show lower net damages than aggregations which consider differences in the marginal utility of income across countries. The evaluation of the net damages thus depends on whether the impacts on poor countries are properly considered. Indeed, the issue of international aggregation of benefits and damages is ethically problematic to an extent that calculating a social cost of carbon at a global level may conceal more than it reveals. 4. The article builds on unsupported assertions and accusations and logical fallacies. “Falsified and sure-to-be-falsified exaggerations from a parade of Ph.D. scientists” Britta Voss Postdoctoral Research fellow, U.S. Geological Survey: The author does not provide any evidence of “falsified” scientific reports of climate predictions or observations. “Peter Wadhams, professor of ocean physics at the University of Cambridge, predicted ‘global disaster’ from the demise of Arctic sea ice—in four years. He too, is eating crow.” Victor Venema Scientist, University of Bonn, Germany: These predictions of Peter Wadhams have been opposed by all climate scientists I know of. This picking of quotes that are convenient for Robert Bradley Jr.’s narrative while ignoring what most climate scientists say is one of his most used rhetorical tools. Kyle Armour Assistant Professor, University of Washington: Indeed. Wadham’s claims have been roundly refuted by the climate science community. They are certainly an example of exaggeration, but to suggest that they somehow represent the scientific mainstream is a great distortion. [See Climate Feedback review of the latest prediction by P. Wadhams] “Can the “uncertainty monster” in climate research, and particularly climate modeling, be acknowledged?” Kyle Armour Assistant Professor, University of Washington: A quick look through the IPCC assessment reports reveals long discussions about uncertainty in our understanding and climate prediction. Moreover, uncertainty in global warming projection exists mainly at the high end—toward more warming—for simple physical reasons. Gary Yohe Professor of Economics and Environmental Studies, Wesleyan University: The scientific community has been scrupulously careful to report uncertainties in terms of “likely” or “confidence”. The planet has warmed; that is unequivocal. Humans have contributed; that is more than 95% assured. See: IPCC 5th Assessment Report Victor Venema Scientist, University of Bonn, Germany: The “uncertainty monster” is a reason to act faster. Uncertainties about how strongly the climate will respond makes the risks of climate change larger. “…obsessing about climate change is avoiding a frank discussion about the here-and-now problems of budget deficits, the federal debt, school choice, entitlement reform, and so on.” Jeremy Fyke Postdoctoral researcher, Los Alamos National Laboratory: Of course, this is a classic false dilemma used by climate change contrarians, which claims that you can’t deal with climate change AND other issues simultaneously. This is patently wrong. “Not only do polls suggest the public is unmoved at home and in abroad…” Britta Voss Postdoctoral Research fellow, U.S. Geological Survey: This claim is incorrect. The source given to support “the public is unmoved at home” is an article titled “Poll: 91% Of Americans Aren’t Worried About Global Warming.” However, this article reports that “only 9.2 percent of Americans rank global warming as their biggest concern.” Not ranking global warming as your biggest concern is not the same thing as not being concerned at all. According to a 2016 Gallup survey, 64% of Americans are “worried a ‘great deal’ or ‘fair amount'” about global warming:"
https://science.feedback.org/review/greenlands-huge-annual-ice-loss-is-even-worse-than-thought-damian-carrington-the-guardian/,1.6,"The Guardian, by Damian Carrington, on 2016-09-23.",,"""Greenland's huge annual ice loss is even worse than thought""",,,,,"Damian Carrington’s article in the Guardian is an accurate summary of a new study advancing estimates of ice lost from Greenland. One of the factors that must be accounted for when monitoring the size of the great ice sheets of Greenland and Antarctica is the vertical motion of the land beneath the ice due to geological forces. The Earth’s crust is depressed under the weight of a growing ice sheet, and will rebound upwards as the ice sheet shrinks. Carrington’s article describes a new study finding greater “crustal rebound” in Greenland, which means some methods of estimating the loss of Greenland ice will have underestimated that loss. The reviewers pointed out that, while this work is important, it doesn’t constitute as much of a breakthrough as is suggested in the article, but mostly confirms that the rate of Greenland ice melt is now 3 times what it was before the industrial revolution.See all the scientists’ annotations in contextGUEST COMMENTS: While I would have preferred a slight moderation of the headline (replace ‘worse’ with e.g. ‘greater’ or ‘larger’) I find the headline accurate and supported by the article. The article explains the novelty and impact of the research accurately for the general readership and in particular the context provided from the scientists works really well in this regard.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Martin Truffer Professor, University of Alaska Fairbanks: The article might not explain the relevance of this work all that well, but there is really nothing controversial being presented here. The Science article presents some important new measurements, but there is no fundamental difference to what we understand about how the icesheet works. Twila Moon Research Scientist, University of Colorado, Boulder: A well-written article that accurately discusses the scientific study and the current state of Greenland research. Allen Pope Research Associate, National Snow and Ice Data Center, University of Colorado Boulder: The article does a good job of accurately portraying and providing insight to the science. A clearer focus on the different timescales involved might have improved it, but it is very good. Lauren Simkins Assistant Professor, University of Virginia: Carrington’s article is a succinct and accurate assessment of past and present ice mass loss from the Greenland Ice Sheet that is supplemented by insightful comments from scientific experts. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from Damian Carrington; comments and replies are from the reviewers. 1. A new estimate of the vertical motion of Greenland’s land surface implies that some monitoring of the Greenland ice sheet has slightly underestimated recent ice loss, which has accelerated due to human-caused warming. “the rapid ice loss recorded by satellite measurements over the last 20 years is not likely to be a blip, but part of a long-term trend being exacerbated by climate change. Global warming is driving major melting on the surface of Greenland’s glaciers and is speeding up their travel into the sea.” While this paragraph is not imprecise, there is a slight wiggle room for the wrong interpretation that the acceleration of ice loss seen in the past decades is just a “blip” on top of a much larger rate of mass loss since the Last Glacial Maximum (LGM). This new work finds the contribution to sea level rise from the Greenland Ice Sheet since the LGM to be 4.6 ± 0.7 m – an average ice loss rate of roughly 75-80 Gt/yr, which is almost identical to the rate of ice loss in the 20th century (75 Gt/yr) suggested by Kjeldsen et al. (2015). The rate of ice loss has accelerated in the past decades so that we today see rates that are more than the triple of those earlier rates. However, I do not think this is a major issue, as the paragraph is sandwiched in between precise explanations and context provided by scientists. Allen Pope Research Associate, National Snow and Ice Data Center, University of Colorado Boulder: Yes, there are two processes going on here: 1) changes still happening in the solid Earth from the last ice age and 2) current changes to the Greenland ice sheet. The former is impacting our ability to measure the latter. “Previous satellite estimates of modern ice losses tried to take this into account, but precise new GPS data showed much of Greenland is rising far more rapidly than thought, up to 12mm a year. This means 19 cubic kilometres more ice is falling into the sea each year, an increase of about 8% on earlier figures.” When scientists use modern data from e.g. satellite gravity measurements to estimate present-day ice loss, we need to correct for land uplift. Because the satellite sees that mass is changing below, but it cannot tell what is due to land motions and what is due to ice loss. The huge Sumatra earthquake caused huge land displacements and changed the gravity field. But for Greenland, changes in gravity are both due to land displacements and ice mass “displacements” or “ice loss”. This new paper solves the problem by using direct GPS measurements of land displacements. Ian Joughin Affiliate Professor, University of Washington: It’s a nice study, but the 20GT/yr represents less than 10% of the observed signal and is well within the uncertainty of those measurements (263+/-30 Gt/year – 2005-2010 loss from Shepherd et al, 2012). Moreover, it’s not clear how well sparsely sampled points constrain their estimates, so there is some uncertainty on the 20Gt/yr (it could be more or less). So while we are always striving to improve measurements of ice sheet mass loss, and this is a step in the right direction, it doesn’t produce any fundamental change in the current estimates of rates of loss from the Greenland ice sheet. Allen Pope Research Associate, National Snow and Ice Data Center, University of Colorado Boulder: It might be worth noting that only some satellite estimates need to take this into account. Especially gravity-based mass change recoveries will be impacted while elevation-change or input/output methods will not. Projects like IMBIE intercompare different methods to build consensus among them. 2. The loss of ice from the Greenland Ice Sheet is a major source of global sea level rise , after thermal expansion of ocean water and melting mountain glaciers outside the polar regions. “The melting Greenland ice sheet is already a major contributor to rising sea level and if it was eventually lost entirely, the oceans would rise by six metres around the world, flooding many of the world’s largest cities.” Lauren Simkins Assistant Professor, University of Virginia: To expand on this statement, observations of ice mass loss indicate that the Greenland Ice Sheet contributes 0.33 [0.25-0.41] mm/yr to global sea level rise. Contributions from thermal expansion and glaciers outside of Antarctica and Greenland are currently the major contributors to global sea level rise followed by contributions from the Greenland Ice Sheet. While it is important to recognize the potential sea level equivalents held up in current ice sheets, complete loss of the Greenland Ice Sheet by 2100 is not reasonable and would likely take thousands of years. For a paleo-perspective, Greenland ice cores and ice sheet models demonstrate that parts (now which parts are up for debate) of the Greenland Ice Sheet did collapse during the last interglacial period (~125,000 years ago) when global mean atmospheric temperature was ~1 degrees C warmer than pre-industrial temperature; however, sectors of the ice sheet remained intact. W. Tad Pfeffer,Professor, University of Colorado: This number [six meters] is quoted in virtually every article published about Greenland (in media and science literature!). It’s really an irrelevant number, and without any context can be very misleading, as it is here. The total loss of the Greenland ice sheet may not happen under any reasonable future scenario, and in any case would take many thousands of years to occur. A more meaningful number would be the current estimate of what the net loss might be by 2100; this could then be given as a percentage of the total ice volume on Greenland, but for the purposes of an article like this, where the reader is thinking about human consequences, quoting the total ice volume will only confuse the issue. Note: While the term “ice cap” is commonly used to refer to several different types of polar features, it technically refers to much smaller areas than Greenland, which should be called an “ice sheet”. “Ice cap is disappearing far more rapidly than previously estimated, and is part of a long-term trend, new research shows” Twila Moon Research Scientist, University of Colorado, Boulder: Again, “ice sheet” is more accurate than “ice cap”. In general, the term “ice cap” is not used in scientific literature. As a result, I think its use is confusing in the media, too, as people have a hard time understanding if it refers to ice sheets (thick ice on land) or sea ice (which are very different!)."
https://science.feedback.org/review/flooding-of-coast-caused-by-global-warming-has-already-begun-justin-gillis-the-new-york-times/,1.7,"The New York Times, by Justin Gillis, on 2016-09-03.",,"""Flooding Coast, Caused by Global Warming, Has Already Begun""",,,,,"Writing for the New York Times, Justin Gillis links the issue of global sea level rise due to climate change to examples of “sunny-day flooding” at high tide along the US East Coast. The 12 scientists who reviewed the article found that it accurately described sea level data and research. Global sea level has risen about 20 centimeters (8 inches) over the past century, contributing to an observed increase in coastal flooding. However, multiple factors affect flooding in coastal communities and many locations along the US East Coast have experienced an even larger sea level change due to additional local factors. The article also discusses research into future sea level rise based on records of past climate changes. While climate scientists generally think that sea level rise will not be greater than 1-2 meters (3.3-6.6 feet) this century, previous warm periods indicate that greater long-term sea level rise should follow in coming centuries—but precisely how much, and how quickly, is not well known. Around 125,000 years ago, for example, the Earth was probably about 1-2°C warmer than it is today, but global sea level may have been 6 meters (20 feet) higher.See all the scientists’ annotations in contextGUEST COMMENTS: Robert Nicholls Professor of Coastal Engineering, University of Southampton: I find this a compelling piece of journalism translating our emerging scientific understanding into an accessible and credible form. It brings home to readers that sea-level rise impacts are being experienced today on the US Atlantic coast. The theory of sea-level rise and flood problems is pretty well understood — this makes the point that this theory is also happening now and can only be expected to get worse — sea levels have been rising on the US east coast for the last 150 years or more and even if current trends simply continue, impacts will continue to grow. As the article states, we actually expect a significant acceleration of sea-level rise in the coming decades meaning the impacts will grow more rapidly. The discussion of the public policy aspects of the issue is also important and shows that we need to start adapting to these changes now — they are only going to get worse.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Andrea Dutton Visiting Associate Professor, University of Wisconsin: This article is well-researched and demonstrates an understanding of the nuances related to the rates of sea-level rise, and how it varies in time and space. This article does a good job at conveying the state of the science and including supporting anecdotal information regarding the inundation of the coastal U.S. due to sea-level rise. Alexis Berg Research Associate, Harvard University: The parts of this article that report on climate science are accurate. In my view, the only thing is that issue of short-term (by 2100) vs long-term (next few centuries) sea level rise projections could perhaps have been explained a bit more clearly: even though total sea level rise by the end of the century is quite uncertain, a sustained 2°C warming almost certainly guarantees a 6 meters sea level rise over the next several centuries. Aimée Slangen Researcher, Royal Netherlands Institute for Sea Research (NIOZ): As far as I can judge, the article is scientifically sound and refers to up-to-date literature, interviewing knowledgeable scientists in the field. I would have liked to see a bit more nuance around the ‘melt’ of land ice though. Lauren Simkins Assistant Professor, University of Virginia: This article supports local perspectives on sea-level rise in the United States with accurate, yet qualitative, scientific observations. Mike MacCracken Chief Scientist for Climate Change Programs, Climate Institute: While there is no real discussion in this article about other factors affecting the coastline (e.g., land subsidence and emergence, local projects that affect movement of sand, the digging of trenches through coastal wetlands, etc.), the contribution resulting from global climate change affecting sea level rise is increasingly dominating the contributions of other factors in most locations. That the present rise of a bit less than a foot since the 19th century is already having so much influence should help to justify the significance and concern in the scientific and defense communities and increasingly in some communities and states regarding the projected additional rise in sea level of two feet and possibly double that over the 21st century. The real uncertainty is becoming not how much the rise will be in the year 2100, but that the world is becoming committed to an ongoing rate of rise of a few to several feet per century, and that what is uncertain is exactly when that much rise will occur rather than if it will occur. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from Justin Gillis; comments and replies are from the reviewers. 1. Average global sea level has risen about 20 centimeters (8 inches) over the last century, and this has contributed to an increase in flooding events at high tide, notably along the US East Coast. “Federal scientists have documented a sharp jump in this nuisance flooding — often called ‘sunny-day flooding’ — along both the East Coast and the Gulf Coast in recent years. The sea is now so near the brim in many places that they believe the problem is likely to worsen quickly.” William Sweet Oceanographer, NOAA Center for Operational Oceanographic Products and Services: This refers to the historical analysis of “nuisance” tidal flooding frequencies (days per year) which we assessed in Sweet et al. (2014). In this report we looked at all tide gauges with hourly data since 1980 and with a threshold for “minor” impacts. When minor flooding (nuisance) is expected, the Weather Forecasting Offices (WFO) typically issues a “coastal flood advisory”; they issue a coastal flood warning when levels are expected to reach moderate or major levels. The minor thresholds I started calling “nuisance levels” and the phrase caught on. Generally nuisance levels vary from 1-2 feet around the U.S. The National Weather Service has a website (AHPS) that includes some of the tide gauge thresholds along with river gauges. Sweet et al (2014) Sea Level Rise and Nuisance Flood Frequency Changes around the United States, NOAA Technical Report Joshua Willis Project Scientist, NASA Jet Propulsion Laboratory: This is accurate. Global sea levels have risen by about 20 cm due to human induced global warming in the last 100 years. Both US coasts have experienced this. It is true that subsidence on the east coast has exacerbated this and the last 20 years of natural variations on the west coast may have given folks a false sense of security because it has opposed or hidden the global rise experienced almost everywhere else. “Along the East Coast, scientists with the National Oceanic and Atmospheric Administration say that many communities have already, or will soon, pass a threshold where sunny-day flooding starts to happen much more often.“ William Sweet Oceanographer, NOAA Center for Operational Oceanographic Products and Services: This relates to the Sweet and Park (2014) paper that uses a 30 days/year threshold as a definition of a tipping point. Though the 30 days/year threshold is somewhat arbitrary, it is sufficiently high that once a region experiences this many floodings, the conversation of what to do to address sea level rise tidal flooding has likely forefront. The “soon” part refers to the fact that number of flooding days per year has (East and Gulf Coast locations) and will continue to accelerate with steady (linear) rises in sea level. Sweet and Park (2014) Acceleration and tipping points of coastal inundation from sea level rise “These tidal floods are often just a foot or two deep, but they can stop traffic, swamp basements, damage cars, kill lawns and forests, and poison wells with salt.” Andrea Dutton Visiting Associate Professor, University of Wisconsin: The depth of flooding is accurate as stated, as shown in Fig. 2 of Sweet and Park (2014) 2. Besides climate change, sea level at any particular location depends on several factors, including local subsidence (lowering of land elevation that can be caused by human activities like groundwater depletion), patterns of ocean circulation… “Federal scientists have documented a sharp jump in this nuisance flooding — often called ‘sunny-day flooding’ — along both the East Coast and the Gulf Coast in recent years.” Benjamin Horton Professor, Earth Observatory of Singapore: This is a tricky one. Nuisance flooding on the Atlantic and Gulf coasts is the result of relative sea-level rise. Relative sea-level rise has a variety of components that give the rise a spatial signature. For example along the mid US Atlantic coast one-third of the rise is due to glacial isostatic adjustment with the remainder dominated by climatically driven sea-level rise. But in the Mississippi Delta the dominant driving force is subsidence. However, in the coming century these components will decrease in importance relative to climatically driven sea-level rise. “Because the land is sinking as the ocean rises, Norfolk and the metropolitan region surrounding it, known as Hampton Roads, are among the worst-hit parts of the United States.” Andrea Dutton Visiting Associate Professor, University of Wisconsin: This statement about the land sinking in the region of Norfolk, leading to higher rates of sea level rise is correct, and is supported by plenty of research, including: Kopp et al. (2014 Probabilistic 21st and 22nd century sea-level projections at a global network of tide-gauge sites, Earth’s Future) “On the Pacific Coast, a climate pattern that had pushed billions of gallons of water toward Asia is now ending, so that in coming decades the sea is likely to rise quickly off states like Oregon and California.” Matthieu Lengaigne Senior Researcher, Institut de Recherche pour le Développement: This statement is likely to be accurate. Several papers already demonstrated the influence of decadal ENSO (El Niño) variations (or the Pacific Decadal Oscillation; PDO) onto the large-scale decadal sea-level variations in the Pacific Ocean (e.g. Zhang and Church 2012). Bromirski et al. (2011) specifically addressed the influence of decadal PDO/ENSO onto the west coast of America and demonstrated an influence of the PDO there, with a suppression of sea-level rise from the 80’s until 2005. As the decadal ENSO/PDO phase is reversing, there is over the past five years an accelerated sea-level rise over the west coast of America (Hamlington et al. 2016) that should continue in the next decade. Zhang and Church (2012) Sea level trends, interannual and decadal variability in the Pacific Ocean. Geophys Res Lett Bromirski et al. (2011) Multidecadal regional sea level shifts in the Pacific over 1958-2008. J Geophys Res. Hamlington et al. (2016) An ongoing shift in Pacific Ocean sea level. Journal of Geophysical Research: Oceans. 3. While global sea level has been stable throughout human civilization history, continuing greenhouse gas emissions growth could result in a sea level rise of 0.5 meters (20 inches) to as much as 1 or 2 meters (3.3-6.6 feet) by the year 2100. But even if rising temperatures are stabilized this century, the world’s ice sheets could continue to shrink long into the future, raising sea levels several meters over coming centuries. “In 2013, scientists reached a consensus that three feet was the highest plausible rise by the year 2100. But now some of them are starting to say that six or seven feet may be possible.” Benjamin Horton Professor, Earth Observatory of Singapore: Yes, I couldn’t agree more. I actually wrote a paper regarding a survey of sea-level scientists. The concluding statement was that most experts estimate a larger sea-level rise by AD 2100 than the IPCC’s Fifth Assessment Report AR5 projects: Horton, Rahmstorf, Engelhart, and Kemp (2014) Expert assessment of sea-level rise by AD 2100 and AD 2300. Quaternary Science Reviews Richard Alley Professor, PennState University: In the 2013 IPCC report, there is a reference period (1986-2005), there is an assumption of a reference pathway of future emissions, and there is a confidence assigned to the estimate. That being said, I think the statement is pretty good. The second sentence is I believe accurate; the work by DeConto and Pollard, building on Pollard et al. (note that I’m involved in this study), for example, points to the possibility of rapid warming triggering rapid sea-level rise. Ken Caldeira Senior Scientist, Carnegie Institution for Science: This is a correct statement, but a key word is ‘some of them’. There have been some people, notably Jim Hansen, who, as I understand it, have been proposing high rates of sea-level rise without providing a mechanism for these sea-level rise rates that seemed plausible to most glaciologists. It is my understanding that the mechanisms proposed by DeConto and Pollard (i.e., mechanical instability of ice cliffs) does appear to be plausible and has some support in observations of ice shelf break-up that has already occurred in Antarctica. In other words, if this sentence were written a year ago, “some of them” would have referred to a few scientists who hold what might be considered ‘outlier’ views. Following the work of DeConto, Pollard, and others, my sense is that the risk of very high rates of sea-level rise seems substantially higher, even to what might be considered ‘mainstream’ scientists. “But the air is already so full of greenhouse gases that most land ice on the planet has started to melt.” Richard Alley Professor, PennState University: Not sure how I would parse “most of the land ice has started to melt”. It is true that there is net mass loss from most mountain glaciers, the Greenland Ice Sheet, and the West Antarctic ice sheet, which numerically makes most of the land ice. But, much of the ice remains too cold to melt, the big central region of East Antarctica is not melting, and much of the sea-level rise from the Antarctic is from faster flow into the ocean (after which the ice does melt…) rather than from melting in place. Aimée Slangen Researcher, Royal Netherlands Institute for Sea Research (NIOZ): I think this is not a very accurate statement and should be nuanced. Rather than ‘melt’, one should talk about ‘mass loss’ (or ‘mass gain’), as melt is not the only process adding to sea-level change. Especially on Antarctica, ice discharge [ice sliding into the ocean] plays a much more important role than melt, as over large parts of the Antarctic Ice Sheet (i.e. inland East Antarctica) the temperatures are so low that surface melt, even in summer, is not an issue at present (see eg these maps of Antarctica surface melt area). If we step away from the ‘melt’ however, […] most glaciers on Earth are suffering from mass loss (IPCC AR5 Chapter 4: “Since AR4 (in 2007), almost all glaciers worldwide have continued to shrink as revealed by the time series of measured changes in glacier length, area, volume and mass”). […] “In the worst-case scenario, this research suggests, the rate of sea-level rise could reach a foot per decade by the 22nd century, about 10 times faster than today.” Ken Caldeira Senior Scientist, Carnegie Institution for Science: We published the results of a study in Science Advances last year (Winkelmann et al., 2015; Combustion of available fossil fuel resources sufficient to eliminate the Antarctic Ice Sheet) concluding that in a worst case scenario, sea level could be rising at an average rate of a foot per decade, averaged over the next 1000 years. Our model, however, did not include the mechanical instability of ice sheet cliffs considered by DeConto and Pollard (2016; Contribution of Antarctica to past and future sea-level rise), which could potentially result in sea-level rises of this magnitude. A key word here is ‘could’. More work needs to be done to assess the likelihood of this occurrence, but sea-level rise rates of a foot per decade by year 2100 appear to be a real risk posed by our greenhouse gas emissions. “During ice ages, caused by wobbles in the Earth’s orbit, sea levels dropped more than 400 feet as ice piled up on land. But during periods slightly warmer than today, the sea may have risen 70 or more feet above the current level.the last sea-level high point, … occurred between the last two ice ages, about 125,000 years ago. … scientists determined that the sea level rose by something like 20 to 30 feet in that era, compared with today. “ Alexis Berg Research Associate, Harvard University: This part would perhaps be a little bit clearer for readers if it included estimates of global temperature change during these different times, to associate with these numbers on sea level change. The last ice age, at its coldest, is estimated to have been on the order of 5 degrees Celsius cooler, in terms of global average, than today. As the article mentions, sea levels then were ~400 feet lower. The last interglacial preceding it, which Dr. Dutton’s research focuses on, was perhaps 1-2C warmer than today (today meaning the pre-industrial climate, before the warming of the recent decades). As the article indicates, sea-levels were perhaps ~6 meters higher at the time. Citing these numbers would help put into perspective, for readers, the projected man-made warming of a few degrees Celsius globally, and explain why the long-term expectations of many scientists … are that sea levels will ultimately rise, over centuries, by “at least 15 or 20 feet” if the globe warms by several degrees in a sustained manner. The questions remains of course, how fast that will occur. Uncertainties on possible rates of sea level rise explain why sea level numbers by 2100 are so uncertain; but what’s virtually certain is that sea level will continue rising beyond that. “Through decades of research, it has become clear that human civilization, roughly 6,000 years old, developed during an unusually stable period for global sea levels.” Andrea Dutton Visiting Associate Professor, University of Wisconsin: The last 6,000 years have been unusually stable for the period of time that we are able to constrain rates of sea-level change particularly well (at sub-millennial timescales): see, for example, Lambeck et al (2014) Sea level and global ice volumes from the Last Glacial Maximum to the Holocene."
https://science.feedback.org/review/sea-level-rise-much-1-2-meters-3-3-6-6-feet-year-2100/,Correct,"The New York Times, Justin Gillis, 2016-09-03",Sea level rise could reach six or seven feet by the year 2100.,,,Continuing greenhouse gas emissions growth could result in a sea level rise of 0.5 meters (20 inches) to as much as 1 or 2 meters (3.3-6.6 feet) by the year 2100.,"In 2013, scientists reached a consensus that three feet was the highest plausible rise by the year 2100. But now some of them are starting to say that six or seven feet may be possible.",,"Benjamin Horton Professor, Earth Observatory of Singapore: Yes, I couldn’t agree more. I actually wrote a paper regarding a survey of sea-level scientists. The concluding statement was that most experts estimate a larger sea-level rise by AD 2100 than the IPCC’s Fifth Assessment Report AR5 projects: Horton, Rahmstorf, Engelhart, and Kemp (2014) Expert assessment of sea-level rise by AD 2100 and AD 2300. Quaternary Science Reviews Richard Alley Professor, PennState University: In the 2013 IPCC report, there is a reference period (1986-2005), there is an assumption of a reference pathway of future emissions, and there is a confidence assigned to the estimate. That being said, I think the statement is pretty good. The second sentence is I believe accurate; the work by DeConto and Pollard, building on Pollard et al. (note that I’m involved in this study), for example, points to the possibility of rapid warming triggering rapid sea-level rise. DeConto and Pollard (2016)Contribution of Antarctica to past and future sea-level rise, Nature Pollard et al (2015) Potential Antarctic Ice Sheet retreat driven by hydrofracturing and ice cliff failure, Earth and Planetary Science Letters Ken Caldeira Senior Scientist, Carnegie Institution for Science: This is a correct statement, but a key word is ‘some of them’. There have been some people, notably Jim Hansen, who, as I understand it, have been proposing high rates of sea-level rise without providing a mechanism for these sea-level rise rates that seemed plausible to most glaciologists. It is my understanding that the mechanisms proposed by DeConto and Pollard (i.e., mechanical instability of ice cliffs) does appear to be plausible and has some support in observations of ice shelf break-up that has already occurred in Antarctica. In other words, if this sentence were written a year ago, “some of them” would have referred to a few scientists who hold what might be considered ‘outlier’ views. Following the work of DeConto, Pollard, and others, my sense is that the risk of very high rates of sea-level rise seems substantially higher, even to what might be considered ‘mainstream’ scientists."
https://science.feedback.org/review/arctic-will-be-ice-free-in-summer-next-year-robin-mckie-peter-wadhams-the-guardian/,-0.6,"The Observer, The Guardian, by Robin McKie, Peter Wadhams, on 2016-08-21.",,"""Next year or the year after, the Arctic will be free ice""",,,,,"The Guardian published an interview with Peter Wadhams, who discusses the consequences of human-induced global warming on Arctic climate and opines that “Next year or the year after, the Arctic will be free of ice”. This claim appears not to be supported by proper scientific argumentation based on evidence and a physical understanding of how that forecast would realize, either in the article or in previously published scientific papers. The scientists who have reviewed the article indicate that while some statements are science-based, several claims are inaccurate or are opinions unsupported by current science. Most of the scientists tagged the article as ‘alarmist’ (meaning that “it overstates or exaggerates the risks of climate change”) and most indicated that the title of the article is not properly supported by its content. Widely publicizing this kind of guess, which has a low probability of turning out to be true, risks undermining public trust in science. Note: scientists’ ratings are intended to assess the credibility of the information contained in an article, regardless of whether a journalist or an “expert” is the author.See all the scientists’ annotations in contextGUEST COMMENTS: Kyle Armour Assistant Professor, University of Washington: The article contains numerous statements that are not supported by the scientific literature, but instead appear to be the personal opinion of Professor Wadhams. It is difficult to provide any meaningful rating for such an interview piece — Wadhams has the right to share his opinions when asked (however unsupported they may be) and at times even makes it clear that his statements are far outside the scientific mainstream. But I give the article low marks overall since it makes no attempt to distinguish which statements are rooted in science and which are simply speculation. Ed Hawkins Principal Research Fellow, National Centre for Atmospheric Science: Peter Wadhams’ views are well known to lie far outside the scientific mainstream. He makes several statements that are inaccurate and some are alarmist. There is no balance in the article from a more mainstream scientist.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Alexis Berg Research Associate, Harvard University: The interview/article should make it clearer that the claim by Prof Wadhams that the Arctic sea ice will be gone this year or next is at odds with mainstream climate science on that topic, and that he has repeatedly made such predictions that haven’t been borne out by subsequent observations. One could argue that climate model projections regarding Arctic sea ice are dire enough that there is no need to repeatedly provide unsubstantiated “guesstimates” of imminent collapse, and that doing so might even detract the public from the slower, but all too real, steady decline in sea ice, or even worse, that it eventually decreases the public’s trust in climate scientists. Allen Pope Research Associate, National Snow and Ice Data Center, University of Colorado Boulder: I gave the “low” rating because the article’s discussion of expected Arctic sea ice retreat is misleading and inaccurate. The statements are not solidly based on the most up to date science. Lauren Simkins Assistant Professor, University of Virginia: While the basic topics mentioned in the article are important to address, some of the statements are misleading and alarmist and the article is more of an opinion piece than a science-supported point. Rasmus Benestad Senior scientist, The Norwegian Meteorological institute: The question concerning sea ice is tricky due to the many and complex factors involved, and the lack of good ice models that embody all scales involved. Patrick Grenier Specialist in climate scenarios, Ouranos: This interview article covers and links several issues (sea ice projections, seabed methane bubbling, carbon capture, etc.), and I agree with some of the messages. The central claim, as conveyed by the title, is that disappearance of the summer Arctic sea ice cover will occur either in 2017 or in 2018. This is not what most sea ice experts consider. Before propagating a marginal view, one should ensure having a very strong argumentation; in this interview no argumentation is put forward to support Peter Wadhams’ central claim. The journalist has chosen to interview a researcher known for having made wrong predictions in the past, and he has chosen not to balance Wadham’s view against that of other sea ice experts. Wadhams’ alarmism is potentially harmful, because when such spectacular predictions are not realized some people may perceive the whole scientific community or science itself as untrustworthy. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from Peter Wadhams; comments and replies are from the reviewers. 1. Sea ice in the Arctic is currently melting at an unprecedented rate and, based on current scientific understanding, one can expect the Arctic to become ice free in summer in about 30-40 years. It is extremely unlikely that the Arctic will become ice free within the next 2 years as claimed in the Guardian article. “Ice-free means the central basin of the Arctic will be ice-free and I think that that is going to happen in summer 2017 or 2018.” Alexis Berg Research Associate, Harvard University: Readers should be reminded that under a business-as-usual greenhouse gas emissions scenario, climate models project an “ice-free” (less than 1 million km2 of ice) Arctic in September by ~2050. Peter Wadhams claims almost every year that it will happen sooner than that, in a matter of a few years – implying some total collapse of Arctic sea ice. This hasn’t happened so far, even if Arctic sea ice is decreasing a bit more rapidly than most models predict. I am borrowing this telling graph from Ed Hawkins (more details in this post):Kyle Armour Assistant Professor, University of Washington: There is no reason to believe that the sea ice cover will disappear this quickly. Our best estimate for this comes from climate models projections, which show that the Arctic could become ice free (less than a million square km) by mid-century — at the earliest — under business-as-usual emissions. Observations show that sea ice is declining somewhat faster than models predict, but even accounting for this suggests that an ice-free Arctic is decades away. Patrick Grenier Specialist in climate scenarios, Ouranos: It is not clear whether a permanent or a one-year phenomenon is meant here (probably the former), but in any case the scientific support for the claim is weak. In the former case (permanent disappearance), this would not correspond to what most sea ice experts do consider. Indeed, section 11.3.4.1 of the last (2013) IPCC assessment report suggests a very low probability for permanent disappearance within the current decade. In fact, from the scientific literature it seems the phenomenon is more likely to take place during the period 2040-2060. Of course, a very low probability does not necessarily mean a zero probability, and IPCC’s report could possibly underestimate the odds for disappearance within the next few years. But before propagating a marginal view (relative to IPCC conclusions), one should ensure having a very strong argumentation; in this interview no argumentation is put forward to support Peter Wadhams’ central claim. In the other possible case (isolated single-year disappearance), it has to be said sea ice has strong year-to-year variability superimposed on its long-term declining trend, and no one has the tools to precisely predict the outcome one year in advance. Seasonal-to-decadal prediction groups equipped with physically-based models have some potential prediction skill for lead times up to 12-24 months, but they currently cannot guarantee to be right for any specific forecast (e.g.: Seasonal Forecasts of the Pan-Arctic Sea Ice Extent Using a GCM-Based Seasonal Prediction System and Pan-Arctic and Regional Sea Ice Predictability: Initialization Month Dependence). So, if it turns out in 2017 or 2018 that Wadhams was right, it will have been luck more than justified certainty. “Next year or the year after that, I think it will be free of ice in summer and by that I mean the central Arctic will be ice-free. You will be able to cross over the north pole by ship. There will still be about a million square kilometres of ice in the Arctic in summer but it will be packed into various nooks and crannies” Ed Hawkins Principal Research Fellow, National Centre for Atmospheric Science: Professor Wadhams has been making this type of prediction in the media for several years, but they have not been borne out by the subsequent observations. For example: Telegraph, 2011 – “ice free by 2015”; Guardian, 2012 – “ice free by 2015 or 2016”; Financial Times, 2013 – “ice free no later than 2015”. Allen Pope Research Associate, National Snow and Ice Data Center, University of Colorado Boulder: I would also add that predictions of an ice-free Arctic (also defined as ~1 million square kilometers of remaining ice) are shown to be subject to quite a bit of uncertainty stemming from natural variability – on the order of about two decades. “Most people expect this year will see a record low in the Arctic’s summer sea-ice cover.” Ed Hawkins Principal Research Fellow, National Centre for Atmospheric Science: This is incorrect. The SIPN team (Sea Ice Prediction Network) have collected forecasts from 40 international groups and none are predicting a record low in 2016. 2. Arctic sea ice melting will make global warming more severe due to several self-reinforcing cycles (known as “positive feedbacks”). “People tend to think of an ice-free Arctic in summer in terms of it merely being a symbol of global change.” Lauren Simkins Assistant Professor, University of Virginia: This is a good point. Changes in one part of the Earth system due to warming are not in isolation and result in feedbacks in other parts of the Earth system. 2.1. When sea ice melts, less solar heat is reflected to space, leading to further warming of the ocean; this is known as the ‘albedo feedback’. “One key effect will be albedo feedback” Rasmus Benestad Senior scientist, The Norwegian Meteorological institute: Albedo is one effect, but it is moderated by cloud cover and only is effective during summer (winter gives dark “polar nights”). Other – perhaps equally important – factors involve the effect open sea has on exchange of moisture, the way temperature varies with height, cloud cover … “These effects could add 50% to the impact of global warming that is produced by rising carbon emissions.” Kyle Armour Assistant Professor, University of Washington: The sea-ice albedo feedback is thought to contribute about 10% to global warming (it’s the smallest of the various climate feedbacks); that’s including the impact of Antarctic sea-ice loss as well. So this estimate of 50% for Arctic sea-ice loss alone seems far too high. Alexis Berg Research Associate, Harvard University: These effects are admittedly included in climate models projections (even though sea ice disappears later in these models than Wadhams suggests here). What Wadhams is describing here is useful to understand these projections, but it doesn’t mean that these effects will come on top of current projections. 2.2. When frozen lands warms (around or at the bottom of the Arctic ocean), it releases methane, a powerful greenhouse gas. Evidence suggests that this “methane feedback” is not yet influencing our climate significantly. “Russian scientists who have investigated waters off their coast have detected more and more plumes of methane bubbling up from the seabed.” Ed Hawkins Principal Research Fellow, National Centre for Atmospheric Science: However, there is evidence from a dedicated field campaign that the methane in ocean plumes does not affect the atmosphere: Extensive release of methane from Arctic seabed west of Svalbard during summer 2014 does not influence the atmosphere “Underneath the permafrost there are sediments full of methane hydrates. When the permafrost goes, you release the pressure on top of these hydrates and the methane comes out of solution” Jeremy Fyke Postdoctoral researcher, Los Alamos National Laboratory: It’s unclear what is meant by ‘permafrost goes’. Nothing particularly ‘goes’ anywhere, it just melts (and has been naturally melting due to post-Last Glacial Maximum sea level rise and the resulting thermal flux due to shelf inundation). Consequentially, I would not expect the pressure seen by the underlying hydrates to decrease if the overlying permafrost degrades. In fact in the real world it will probably increase due to anthropogenic sea level rise. So it will necessarily be an anthropogenic temperature pulse, not a pressure pulse that will destabilize methane hydrates under relic permafrost. Finally, methane molecules in hydrates is not ‘in solution’ but rather in the hydrate crystalline lattice. 3. While sea ice melt does not directly cause the sea level to rise, it helps warm and melt on-land-glaciers (e.g. Greenland) that do cause sea level rise. “The most recent prediction of the Intergovernmental Panel on Climate Change (IPCC) is that seas will rise by 60 to 90 centimetres this century. I think a rise of one to two metres is far more likely.” Lauren Simkins Assistant Professor, University of Virginia: This range is not entirely accurate. Using different climate scenarios, global mean sea level is predicted to rise by 0.26 to 0.98 m by the end of the century. This does not include potential collapse of marine-based sectors of the Antarctic Ice Sheet, which could raise these estimates. Recent work suggests that Antarctica’s contribution to sea level could contribute more than 1 m to sea level rise on top of the IPCC AR5 estimates. Remark: Some of the article’s language is imprecise “the first scientists to show that the thick icecap that once covered the Arctic ocean was beginning to thin and shrink.” Lauren Simkins Assistant Professor, University of Virginia: Arctic sea ice is typically less than 4 m thick. The use of ‘ice cap’ traditionally implies a body of ice on land that covers less area than an ice sheet; however, the article discusses sea ice, not an ice cap, which is floating ice that forms due to freezing of surface water. Jeremy Fyke Postdoctoral researcher, Los Alamos National Laboratory: This is a misleading term. Ice caps are technically large land-based glaciers, whereas I think ‘Arctic icecaps’ here mean Arctic sea ice.“‘Next year or the year after, the Arctic will be free of ice’” Lauren Simkins Assistant Professor, University of Virginia: The title is misleading. Wadhams suggests that the central Arctic (only) will be ice free in the summer. "
https://science.feedback.org/review/louisiana-flooding-natural-disaster-weather-climate-change-oliver-milman-the-guardian/,1.3,"The Guardian, by Oliver Milman, on 2016-08-16.",,"""Disasters like Louisiana floods will worsen as planet warms, scientists warn""",,,,,"The article reports on the historic floods that recently occurred in Louisiana and discusses the influence of human-induced climate change on heavy-precipitation events. Overall, the article correctly places this event in its climatic context: science clearly shows one should expect to observe more frequent intense rain events as the planet continues to warm, since it allows the atmosphere to contain more moisture. However, an increase in “flooding” severity related to global warming has not yet been clearly established.See all the scientists’ annotations in contextGUEST COMMENTS: Andrew King Research fellow, University of Melbourne: Overall, the article does a good job of putting the recent heavy rainfalls in Louisiana into the broad context of climate change. While generally we expect to see more heavy downpours as the climate warms, there is a crucial caveat that’s missing- changes in the frequency of some weather systems may mean that for particular locations we wouldn’t see more extreme rainfall events. In the absence of a specific attribution study examining the role of human-induced climate change in this kind of event, we cannot say for certain that climate change increased the likelihood or intensity of these recent rains. This detail is particularly important in places like Louisiana where extreme rainfall events can arise from different weather systems, like hurricanes for example, and there is uncertainty in how climate change is influencing some of these weather events. Michela Biasutti Lamont Associate Research Professor, Lamont Doherty Earth Observatory, Columbia University: This piece gives a pretty standard overview of the state of the science as it pertains to extreme rainfall events and their link to climate: theoretical and model evidence (and, increasingly, observations) suggest that daily extreme precipitation will become more intense, so that high-intensity thresholds will be exceeded more often. The piece is also careful in providing some clarification that this general trend will not necessarily be universal. One possible nuance that might be worth noting is that the link between rainfall and flooding depends heavily on landscape modification as well.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Alexis Berg Research Associate, Harvard University: In my view, this article does a good job reporting on the recent floods in Lousiana and, more generally, the climate-change-induced changes in the water cycle that underlie scientists’ concerns about future increase in floods. However, “heavy rainfall” is not strictly synonymous to “flooding”, and I think it could have provided more context on what is known (or not known) about current, observed changes in floods. Ben Henley Postdoctoral research fellow, University of Melbourne: The article is accurate. The issue of increasing precipitation extremes due to climate change is presented well. Heavy precipitation increases have been observed, and are projected to worsen with climate change. The complexities of ocean-atmosphere circulation changes due to climate change are an area of active scientific research. Increased research in this area will help us answer the public’s questions on the human fingerprint on extreme events. Laurens Bouwer Senior risk advisor, Deltares: The article provides a good representation of the facts, and adds an evaluation of uncertainties, as well as pertinent quotes from experts. Various references to appropriate scientific documentation are provided as well. Further, evidence exists attributing the increase in extreme rainfall to global warming, as summarized in the IPCC 5th report, and more importantly, there is a long line of work attributing changed likelihood of occurrence of single events -like the Louisiana flooding- to climate change (called ‘event attribution’). Both of these topics are not mentioned explicitly, which makes the article quite careful and modest on these issues. James Renwick Professor, Victoria University of Wellington: Very well-written and well-explained article, using the latest scientific understanding. Rasmus Benestad Senior scientist, The Norwegian Meteorological institute: This is an important news report, however, the actual problem is somewhat under-communicated since it mixes return value analysis for a single site with occurrences taking place over many sites. The situation is more dramatic because extreme rains and flooding could happen in many places, and the likelihood for seeing such events is much higher than the probability associated with one specific site. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from Oliver Milman; comments and replies are from the reviewers. 1. As the climate warms due to human activities, the atmosphere can hold more moisture and this is creating more favourable conditions for extreme rain events. “as surface temperatures of the oceans warm up, the immediate response is more water vapor in the atmosphere. We’re in a system inherently capable of producing more floods.” James Renwick Professor, Victoria University of Wellington: Exactly. Every degree C of warming equates to around 7% more water vapor in the air. Not only does this lead to heavier rain, it adds to the warming as water vapor is a potent greenhouse gas. “While the north-east, midwest and upper great plains have experienced a 30% increase in heavy rainfall episodes – considered once-in-every-five year downpours – parts of the west, particularly California, have been parched by drought.” Rasmus Benestad Senior scientist, The Norwegian Meteorological institute: It is expected that an increased greenhouse effect will result in wet areas becoming wetter and dry regions drier because the atmospheric overturning (convection) will respond to the atmospheric opacity [1]. Overturning means air rising in some parts and sinking in others. Rising air (convection) brings moisture aloft where it cools, condenses, forms clouds, and precipitates. The descending air is dry as it is air that previously ascended and where the moisture has precipitated out during the ascent. [1]A mental picture of the greenhouse effect “The contrast in precipitation between wet and dry regions and between wet and dry seasons will increase, although there may be regional exceptions.” Alexis Berg Research Associate, Harvard University: While this picture might provide a leading order approximation, it is mostly valid over the oceans. Over land, recent research has shown that the “wet get wetter, dry get drier” picture does not really apply and things are a little more complex (e.g., see: Byrne and O’Gorman. “The Response of Precipitation Minus Evapotranspiration to Climate Warming: Why the “Wet-Get-Wetter, Dry-Get-Drier” Scaling Does Not Hold over Land” Journal of Climate (2015).) “On Tuesday, the National Oceanic and Atmospheric Administration (Noaa) is set to classify the Louisiana disaster as the eighth flood considered to be a once-in-every-500-years event to have taken place in the US in little over 12 months.” Laurens Bouwer Senior risk advisor, Deltares: This last sentence seems to imply that this is exceptional. However, in a country as large as the USA, it is very well possible to have multiple events each year, that exceed 100 or 500-year frequency thresholds for a particular location. Note that for this case, for multiple locations, the 500-year rainfall amount was exceeded, which is indeed exceptional. Alexis Berg Research Associate, Harvard University: As others pointed out, over a large area like the US, it is not necessarily out of the ordinary to have several places experience rare events – like record floods – in the same year. Further analysis would be required to see if the combination of these events is really unusual. Overall, while there is an observed increase in heavy rainfall event that has been attributed to man-made global warming, changes in floods are more difficult to observe and attribute. The 2012 report on climate extremes from the IPCC indicates that “There is limited to medium evidence available to assess climate-driven observed changes in the magnitude and frequency of floods at regional scales because the available instrumental records of floods at gauge stations are limited in space and time, and because of confounding effects of changes in land use and engineering. […] Further, it points out that, so far, there is “Low confidence that anthropogenic warming has affected the magnitude or frequency of floods at a global scale.” […] So the picture appears complex and uncertain, and while the title of this article is broadly consistent with the last quote above, caution is warranted when interpreting recent flooding events with respect to climate change. For the US in particular, recent research indicates an increase in flooding frequency (but not necessarily magnitude) in the Northern Central US (see Mallakpour and Villarini. “The changing nature of flooding across the central United States.” Nature Climate Change (2015)) “Noaa considers these floods extreme because, based on historical rainfall records, they should be expected to occur only once every 500 years.” James Renwick Professor, Victoria University of Wellington: This means that such a flood is expected to have a 1 in 500 chance of happening in any given year. It does not imply that such event occurs regularly every 500 years though. That statistic would hold if the climate were not warming. Since warming is occurring, and the amount of moisture in the air is increasing, the odds of getting these floods are getting larger/more likely. 2. A record high amount of atmospheric moisture helped generate extreme rainfall levels in Louisiana; in similar situations, other factors (like topography, urban planning, wind patterns…) usually contribute to the magnitude of the resulting flood. “The National Weather Service balloon released in New Orleans on Friday showed near-record levels of atmospheric moisture, prompting the service to state: “We are in record territory.” Emmanuel Vincent Founder & Executive Director, Science Feedback: The chart below from the National Weather Service’s Storm Prediction Center shows that the amount of ‘Precipitable Water’ in the atmosphere over southern Louisiana (Baton Rouge) was unprecedented just before the flood. This flood fits a pattern: a recent study found that most urban flood events over the past 40 years exhibit very high amounts of precipitable water in the atmosphere. see Schroeder et al Insights into Atmospheric Contributors to Urban Flash Flooding across the United States… (2016) Journal of Applied Meteorology and Climatology. 3. An attribution study will be needed before one can properly quantify whether -and by how much- global warming made this particular flood more likely and/or more intense. “While scientists are loathe to attribute any single event to changes in the climate, they state that warming temperatures are helping tip the scales towards altered precipitation. Some, however, bristle at the belief that because floods and storms have always occurred, they should not be linked to climate change” Rasmus Benestad Senior scientist, The Norwegian Meteorological institute: It is true that floods and storms always have occurred, but they have always ocurred for a physical reason. This may be evidence suggesting that these phenomena are rather sensitive to a climate change, if modest natural changes in physical conditions already give rise to variations in the floods and storm activity. We now know that the earth’s atmosphere is changing (increased CO2 and a global warming). It would be naive to think that floods and storms do not change when important factors change while they have always changed in the past. It is also important to think about these concepts in a risk-analysis frame, and it is important to plan for various plausible scenarios. Adam Sobel Professor, Columbia University: Observations over the US and many other places around the world show that heavy rain events have been becoming heavier over the last several decades. Climate models very consistently predict that this should happen as the climate warms, and basic physics leads us to interpret this change as, in large part, a consequence of increasing water vapor in the atmosphere. On this basis we can say that climate change has most likely increased the probability of an event like this. One still can’t say that climate change ’caused’ this event, as each event has many causes and no event can be viewed solely as a consequence of long-term trends. No study can tell us that climate change caused an event like this to happen, full stop. Every weather event has many causes. Climate change is just one of them, and usually not the most immediate. At most it can push things a bit in one direction, making the weather more severe if it was going in that direction anyway. Attribution studies can describe and quantify that push. (more details in this article)"
https://science.feedback.org/review/environment-climate-change-records-broken-international-report-oliver-milman-the-guardian/,1.3,"The Guardian, by Oliver Milman, on 2016-08-02.",,"""Environmental records shattered as climate change 'plays out before us'""",,,,,"The article summarizes the main findings of the “2015 state of the climate” report published by the National Oceanic and Atmospheric Administration. Overall it accurately reports the main findings that many global indicators of the Earth’s climate, notably the global surface temperature, have set new records in 2015 under the joint influence of ongoing human-induced climate change and a strong El Niño event. However, scientists noted a few issues with the article, such as minor errors, a lack of background and references for some key claims and a potentially misleading attribution of Indonesian fires to climate change.See all the scientists’ annotations in contextGUEST COMMENTS: Twila Moon Research Scientist, University of Colorado, Boulder: This article does a good job of summarizing results in the State of the Climate report. However, there are some areas (e.g., Greenland sea level rise contributions and extent of surface melt) where the information is not directly pertinent to modern-day effects of climate change or is presented without context. It is difficult to present so many scientific results regarding climate change in such a short article, and the author doesn’t always succeed at providing the necessary context. Nevertheless, the title clearly conveys the sum total of recent observations, which now show definite fingerprints of climate change in our annual weather.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Keven Roy Research Fellow, Nanyang Technological University: The article did a good job at summarizing the “State of the Climate 2015” report by the AMS. There were few prominent mistakes (the confusion regarding the 90+% of the total extra heat absorbed in the climate system being stored in the oceans stands out) and a few language imprecisions, but overall it conveyed the information and the main conclusions clearly. Victor Venema Scientist, University of Bonn, Germany: The general reader will get a fair impression about the state of the climate in 2015, but the scientifically interested reader will also find several irritating and unnecessary mistakes in details. Jan Lenaerts Assistant Professor, University of Colorado, Boulder: The article is accurate and reflects the report. It is a little vague here and there, but useful for a general audience. Good review of the State of the Climate report. Does appear to conflate climate change with El Niño effects, but at the same time highlights a quote regarding the dual contributions of El Niño and climate change to climate anomalies in 2015. Rasmus Benestad Senior scientist, The Norwegian Meteorological institute: The main picture provided by this report is consistent with the science, although there was a minor mistake (ocean uptake of CO2). Stephan Lewandowsky Professor, University of Bristol: The other commenters have admirably picked up on the slight inaccuracies in the article. I nonetheless believe that a “+2” is in order because the glitches are quite subtle (with the possible exception of confusing 90% of heat with 90% of CO2). On balance, it is very clear that the author tried to convey complex material accurately and this effort was quite successful. Jennifer Francis Senior Scientist, Woods Hole Research Center: The string of records broken and nearly broken in 2015 is stunning, and the story continues into the first half of 2016. Clearly a strong El Niño “juiced” the already disturbed climate system, but the Earth’s behavior in 2015 and recent months may be a preview of a future when global-average warming approaches the 2-degree C level that is generally expected to bring dangerous consequences. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from Oliver Milman; comments and replies are from the reviewers. 1. The average temperature at the surface of the planet shattered previous records in 2015, and 2016 will very likely break this record. While El Niño gave a boost to global temperatures, these records are mostly due to the long-term warming trend. “This means that the world is now 1C warmer than it was in pre-industrial times” Victor Venema Scientist, University of Bonn, Germany: The temperature is 1°C warmer than in the beginning of the instrumental temperature record (1880). The 19th century was likely a little colder than the pre-industrial period. This difference is not large and currently being studied, but likely we did not cross the 1°C warming relative to pre-industrial yet. Global temperature in the Berkeley Earth dataset from 1850 to 2015 “The UN has already said that 2016 is highly likely to break the annual record again, after 14 straight months of extreme heat aided by a hefty El Niño climatic event, a weather event that typically raises temperatures around the world.“ Victor Venema Scientist, University of Bonn, Germany: The influence of El Niño was likely not as large as it was in 1998. A large part of the warming was also in the Arctic, as Jan Lenaerts also argues below. Jan Lenaerts Assistant Professor, University of Colorado, Boulder: I would say that it increases ‘global mean temperature’. An El Niño does not necessarily imply warming everywhere on Earth. Also, especially pronounced are the warm conditions in the Arctic, which are not explicitly mentioned here, but do not relate to the strong El Niño. The first six months of 2016 were the warmest six-month period in NASA’s modern temperature record, which dates back to 1880. Credits: NASA/Goddard Institute for Space Studies 2. Global Sea Level has set a new record in 2015, boosted by melting glaciers around the world and increasing ocean heat content that causes the water to expand. “The thermal expansion of the oceans, compounded by melting glaciers, resulted in the highest global sea level on record in 2015.” Keven Roy Research Fellow, Nanyang Technological University: This statement in the AMS report refers to the satellite altimetry record, which reaches back to 1993. It is also important to remember that it refers to the global average sea level. We do have local records of past sea level that extend further back in time, for instance tide gauge records or inferences based upon biological markers. For instance, combined tide gauge records have been used to infer global mean sea level rise (GMSL) over the 20th century and into the 21st century. The obtained estimate of the GMSL rise agrees with the satellite altimetry record in their overlap since 1993 (e.g., Hay et al., 2015: Probabilistic reanalysis of twentieth-century sea-level rise). “The oceans, which absorb more than 90% of the extra CO2 pumped into the atmosphere“ Rasmus Benestad Senior scientist, The Norwegian Meteorological institute: Here “CO2” should be “heat” … according to the Scripps Institute, the uptake of CO2″ is about 26%. Keven Roy Research Fellow, Nanyang Technological University: “The oceans, which absorb more than 90% of the extra CO2 pumped into the atmosphere” should read “The oceans, which absorb more than 90% of the extra heat pumped into the climate system“. “The world’s alpine glaciers recorded a net annual loss of ice for the 36th consecutive year and the Greenland ice sheet … experienced melting over more than 50% of its surface.” Jan Lenaerts Assistant Professor, University of Colorado, Boulder: That is correct, see figure below: There was an event in the beginning of July when ~50% of the ice sheet experienced melt. This is clearly outside of the expected natural variability, but does not necessarily project the overall Greenland summer (since such melt events are extremely episodic). Overall, Greenland experienced a warm summer, with slightly more surface runoff than average and overall average amounts of snowfall (source) Twila Moon Research Scientist, University of Colorado, Boulder: This is true. Perhaps more important, though, is that surface melt in Greenland started early this year and included several large spikes. While current surface melt is not currently larger than the record-breaking 2012 melt year, it is ahead of 2013-2015 so far. The NSIDC has an excellent summary of current melt status for Greenland here. “Greenland ice sheet … would balloon sea levels by around 7m should it disintegrate” Twila Moon Research Scientist, University of Colorado, Boulder: This is a reasonable number for the total mean sea level rise if all of the Greenland Ice Sheet melted. Total melt of the Greenland Ice Sheet, however, is essentially impossible over the next several hundred years. Nevertheless, the Greenland Ice Sheet has been losing large amounts of ice and the rate of loss has increased over the recent decade or so (references include this paper and this one). The amount of ice Greenland has lost to date has already raised global sea levels and projections indicate the possibility of 0.5 m more sea level rise from Greenland alone over the coming several centuries. 3. While some anomalous climate events of 2015 can be related to climate change with high confidence (eg record low in Arctic sea ice area), such a connection is not established for other events (eg drought in Indonesia). “other “remarkable” changes in 2015 include the Arctic’s lowest maximum sea ice extent in the 37-year satellite record, recorded in February 2015.” Jennifer Francis Senior Scientist, Woods Hole Research Center: The graphs below show a best estimate of ice extent for the period 1850 to 2013 for winter and summer. Source: NSIDC “The rapid changes in the climate may have profound consequences for humans and other species… Severe drought caused food shortages for millions of people in Ethiopia, with a lack of rainfall resulting in “intense and widespread” forest fires in Indonesia that belched out a vast quantity of greenhouse gas” Technically correct, in that drought due to lack of rainfall is linked to Indonesian forest fires in some El Niño years. The lead sentence for the paragraph implies a link between climate change and the following events, including Indonesian forest fires, which is not established. To the extent that climate change might be affecting the frequency and intensity of El Niño events or rainfall patterns during El Niño events, it might be playing a role, but that is not claimed in this article. For example, Dai 2012 (Increasing drought under global warming in observations and models) documents a decreasing observed precipitation trend in Indonesia, but Trenberth, Dai et al 2014 (Global warming and changes in drought) note that “it is probably not possible to determine reliable decadal and longer-term trends in drought without first accounting for the effects of ENSO and the Pacific Decadal Oscillation.” Trenberth, Dai et al also note that drought due to El Niño effects on precipitation may also be exacerbated by the effects of warming on evapotranspiration, which is an area of ongoing study."
https://science.feedback.org/review/science-about-links-between-global-warming-and-massive-heat-waves-chris-mooney-washington-post/,1.7,"The Washington Post, by Chris Mooney, on 2016-07-21.",,"""What science can tell us about the links between global warming and massive heat waves""",,,,,"The Washington Post reports on the “massive heat wave” that is currently affecting the US and explores the question of how such events are related to human-induced global warming. The scientists who have reviewed the article confirm that it accurately describes the state of scientific knowledge on the topic. While the observed increased frequency, severity and duration of heat waves in some parts of the world are among the most certain impacts of climate change, calculating any increases to the current heat wave’s probability or intensity as a result of global warming will require a specific study (called an “event attribution study”), which has not yet been performed for the current event as of July 25th.See all the scientists’ annotations in contextGUEST COMMENTS: Andrew King Research fellow, University of Melbourne: This is a well-written article that provides a good overall discussion around the connection between climate change and the ongoing US heat wave. In the absence of a specific event attribution study the role of climate change in this event can’t be quantified, but Chris Mooney provides an insightful overview of the role of climate change in heat events generally. Friederike Otto Deputy Director Environmental Change Institute, University of Oxford: I do not find anything wrong with the article. And it makes the key point that robust event attribution is now possible. However, the article could better help readers understand what ‘event attribution’ is in contrast to ‘predictions’. The article makes the point that it is now possible to attribute individual classes of extreme events to climate change: eg heat waves in a specific region and season. It is not clear in pointing out that the reason for having to do a specific ‘attribution study’ is to quantify the role anthropogenic climate change played in an event given the observed class of heat wave. While on average we see an increase in heat wave frequency and intensity, there are parts of the world where there is actually hardly any increase (e.g. parts of India in the pre monsoon season) while for others the likelihood of certain types of heat waves to occur has increased at least 10 fold (eg Central Europe).REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Geert Jan van Oldenborgh Senior researcher, KNMI (The Royal Netherlands Meteorological Institute): The article gives a fair and balanced view on the topic. The one proviso that is not made that could have been added is that increasing air pollution with aerosols that block sunlight can counteract the effect of greenhouse gases on heat waves, as was the case in Europe up to the mid-1980s and is the case now in some other parts of the world such as India. However, the opposite is happening in the United States where clearer skies also increase the risk of severe heat waves. There are other factors, such as drying soils, that can exacerbate a heat wave, so indeed a specific study is needed to know how much the present heat wave can be attributed to global warming. Ken Caldeira Senior Scientist, Carnegie Institution for Science: This article is very good because it relies on quality documents including a National Academies report and the US Climate Assessment. It quotes several scientists who reflect the broad consensus of scientists who work on extreme event attribution. The story makes the point that with global warming, extreme heat waves will become more common and more intense, yet just as you cannot say with 100% confidence that a smoker would not have died of cancer had he not smoked, we cannot with 100% confidence attribute any particular heat wave to climate change. However, just as statistics, combined with mechanistic understanding, clearly demonstrate that smoking cigarettes causes cancer, statistics, combined with a mechanistic understanding of climate physics, clearly demonstrate that the accumulation of greenhouse gases in the atmosphere is causing an increase in the frequency and intensity of heat waves. Overall, an excellent article. Twila Moon Research Scientist, University of Colorado, Boulder: This well-explained article accurately represents the current science for understanding the contribution of climate change to extreme events such as heat waves. Victor Venema Scientist, University of Bonn, Germany: A fair summary of the scientific current understanding of the observed increases in heat waves and their relations with global warming. Doug Smith Senior researcher, UK Met Office: A balanced overview. Sarah Perkins-Kirkpatrick Research Scientist, Climate Change Research Centre, The University of New South Wales: This article is very accurate, a little oversimplified in some areas, but that can be difficult to overcome. Patrick Grenier Specialist in climate scenarios, Ouranos: The journalist is right regarding his main point: it cannot be told that global warming is the cause of a specific extreme event (unless it could not have existed without global warming); the issue must be addressed with probabilities, comparing all events we experience with all events we would have got without global warming. However, the point is not well illustrated by the current heat wave in Eastern US, since this region is precisely known for showing negative long-term trends in many extreme heat indicators. In summary, the main point is insightful and applies globally, but the journalist does not illustrate it with the most appropriate event, because projected increases in the indicators of extreme heat over Eastern US have not clearly got out of the natural variability so far. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time.Key Take-aways : The statements quoted below are from Chris Mooney; comments and replies are from the reviewers. 1. Heat waves in the U.S. have already become more frequent and intense due to human induced global warming. “And the gist is that when it comes to extreme heat waves in general — heat waves that appear out of the norm in some way, for instance in their intensity, frequency, or duration — while scientists never say individual events are “caused” by climate change, they are getting less and less circumspect about making some connection.” Andrew King Research fellow, University of Melbourne: This is certainly true. Over the last few years we’ve seen more and more attribution statements related to heat waves (where there is higher confidence in the climate change link compared with other extremes, such as heavy rain events) and scientists have become more confident in making this connection. Rasmus Benestad Senior scientist, The Norwegian Meteorological institute: “Climate change” is by definition a shift in the weather statistics, such as the curve that describes the likelihood of temperatures exceeding a certain threshold [see figure below]. The temperature has a statistical character that is close to being bell-shaped (normal distribution), which implies that high temperatures are expected to be more frequent with a global warming – unless the typical range of temperatures (standard deviation) or shape of the curve changes as well. Climate is the typical character outlined by this curve (probability density function) describing the probabilities, whereas weather is each different data point on which this curve is based. When referring to one event – one data point – one talks about weather. Weather is not the same as climate, but they are related: climate is the expected weather. Figure illustrating how a change in climate influences the frequency of extreme heat events: an increase in the average temperature (upper panel) causes a large increase in the probability of extreme hot events; a change in the climate variability (lower panels) can further alter the frequency of extreme events. – adapted from IPCC report (2001) “The U.S. National Climate Assessment found that U.S. heat waves have already “become more frequent and intense,” that the U.S. is shattering high temperature records far more frequently than it is shattering low temperature records (just as you’d expect), and that it is seeing correspondingly fewer cold spells.” Andrew King Research fellow, University of Melbourne: This is true and is also consistent with findings from other areas of the world. For example, Dr Sophie Lewis led work that showed in Australia there have been 12 times as many hot records compared to cold records since 2000. 2. In order to calculate how much climate change has exacerbated a given heat wave (or made it more likely), an event attribution study is needed; such a study has not yet been completed for the current heat wave. “Typically, in such an attribution study, scientists will use sets of climate models — one set including the factors that drive human global warming and the other including purely “natural” factors — and see if an event like the one in question is more likely to occur in the first set of models. Researchers are getting better and better at performing these kinds of studies fast, in near real time.” Andrew King Research fellow, University of Melbourne: This is an accurate description of how extreme event attribution studies are conducted. 3. Heat waves cause severe risks to health, particularly for children and elderly people. Some deaths due to heat waves can be directly attributed to climate change. “this event poses severe risks to health — particularly for children and the elderly […] an extreme 2003 heat wave that affected Paris and Europe, and which has indeed been connected to climate change through statistical attribution analysis […] killed hundreds of people in Paris and London, and a recent study attributed at least some of those deaths, themselves, to climate change.” Victor Venema Scientist, University of Bonn, Germany: Only mentioning the deaths in two cities understates the danger of heat waves. The number of people who died in the 2003 heat wave is estimated to be in the tens of thousands. This article estimates it was 70 thousand additional deaths. Kristie Ebi Professor, University of Washington: The majority of injuries, illnesses, and deaths during heatwaves are preventable. A robust literature base documents individuals at higher risk during heatwaves, such as adults over the age of 65 years, infants, individuals with certain chronic diseases, and others. Heatwave early warning and response systems save lives; expanding these systems to more cities and increasing awareness of the health risks of high ambient temperatures could increase resilience as heatwaves increase in frequency, intensity, and duration. Another issue is that growing confidence that climate change is increasing the probability of heatwaves means some deaths during heatwaves could be attributed to climate change. Sarah Perkins-Kirkpatrick Research Scientist, Climate Change Research Centre, The University of New South Wales: When the 2003 European heatwave occurred it killed 70 000 people. At the time the likelihood of that event occurring had doubled due to human influence. Now an event like this is 10 times more likely due to human influence. References: Stott et al (2004) Human contribution to the European heatwave of 2003. Nature. Christidis et al (2015) Dramatically increasing chance of extremely hot summers since the 2003 European heatwave. Nature Climate Change. Trigo et al (2005) How exceptional was the early August 2003 heatwave in France?. Geophysical Research Letters."
https://science.feedback.org/review/heat-waves-u-s-already-become-frequent-intense-due-global-warming/,Accurate,"The Washington Post, Chris Mooney, 2016-07-21",the U.S. is shattering high temperature records far more frequently than it is shattering low temperature records,,,"Because of human-caused global warming, heat waves in the U.S. are becoming more common and the hottest heat waves are getting hotter. Weather is naturally variable, but the trend of warming temperatures means that local record highs are set more often, and record lows less often.","The U.S. National Climate Assessment found that U.S. heat waves have already 'become more frequent and intense,' that the U.S. is shattering high temperature records far more frequently than it is shattering low temperature records (just as you’d expect), and that it is seeing correspondingly fewer cold spells.",,"Andrew King Research fellow, University of Melbourne: This is true and is also consistent with findings from other areas of the world. For example, Dr Sophie Lewis led work* that showed in Australia there have been 12 times as many hot records compared to cold records since 2000. Lewis and King (2015) Dramatically increased rate of observed hot record breaking in recent Australian temperatures, Geophysical Research LettersRasmus Benestad Senior scientist, The Norwegian Meteorological institute: “Climate change” is by definition a shift in the weather statistics, such as the curve that describes the likelihood of temperatures exceeding a certain threshold [see figure below]. The temperature has a statistical character that is close to being bell-shaped (normal distribution), which implies that high temperatures are expected to be more frequent with a global warming – unless the typical range of temperatures (standard deviation) or shape of the curve changes as well. Climate is the typical character outlined by this curve (probability density function) describing the probabilities, whereas weather is each different data point on which this curve is based. When referring to one event – one data point – one talks about weather. Weather is not the same as climate, but they are related: climate is the expected weather. Figure illustrating how a change in climate influences the frequency of extreme heat events: an increase in the average temperature (upper panel) causes a large increase in the probability of extreme hot events; a change in the climate variability (lower panels) can further alter the frequency of extreme events. – adapted from IPCC report (2001)Sarah Perkins-Kirkpatrick Research Scientist, Climate Change Research Centre, The University of New South Wales: This is certainly true—the distribution of temperature is shifting towards warmer conditions. This allows for a large increase in the frequency of heatwaves, as well as an increase in their intensity. But the amount of change depends largely on the area of focus. Some regions have a much wider temperature distribution than others. Changes in the variability of the temperature distribution will also influence by how much extreme events like heatwaves will change. Almost all attribution studies on extreme heat conditions have come back with some measurable human influence. The amount of this influence varies a lot, and therefore, is specific to the event analysed. But in general, yes, there is a detectable human influence behind extreme hot temperature events."
https://science.feedback.org/review/climate-change-emergency-jet-stream-shift-warning-global-warming-extreme-weather-gabriel-samuels-the-independent/,-1.4,"The Independent, by Gabriel Samuels, on 2016-06-30.",,"""Scientists warn 'global climate emergency' over shifting jet stream""",,,,,"The article repeats claims made by two bloggers that upper-level winds crossing the equator would be an unprecedented consequence of climate change. In reality, such wind features are frequently observed and the central claim of the article is thus unsupported by science. Note: The Independent has updated the article on July 1st, by: changing the subtitle of the article from the initial “Experts say drastic weather changes could cause ‘massive hits to food supply’ and ‘death of winter’” to “Other scientists have since dismissed the claims as ‘total nonsense’”; adding a sentence linking to a rebuttal of the claims that reads “However other scientists dismissed their claims, with one describing their concern over wind crossing the equator as “total nonsense”.” Unfortunately the original inaccurate article has been shared 10k times on social media while the correction has only been shared 150 times (as of July 5th 2016).See all the scientists’ annotations in contextGUEST COMMENTS: Edwin Gerber Associate Professor, New York University: This article makes little sense. It uses scientific jargon, such as in the last paragraph, to make it sound “scientific”, but uses it so loosely that it has no meaning. I do not see any logic behind these wild claims, there are no connections with established research, and there is no discussion of statistical certainty. Moreover, wild attributions to anthropogenic climate change are made without any backing. Winds routinely cross the equator in the monsoonal circulations. This happens every year, without any grave consequences for climate.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Tim Woollings Lecturer, University of Oxford: The article seems to truthfully repeat the bloggers claims, but with no attempt to verify these claims from other sources. Unfortunately the claims are ridiculous. This snapshot is clearly just a weather pattern, rather than any long-term change. To put things in context, we do expect the jet streams to move in response to climate change, but only by a couple of degrees of latitude over the coming century. Emmanuel M Vincent Research Scientist, University of California, Merced: This article reports on speculations made by bloggers without any appropriate fact-checking. Had the journalist contacted actual scientists, it would have been easy for him to understand that the claims are without any scientific substance. One can only wonder whether this lack of fact-checking is intentional to create a click-bait headline and generate buzz on social media. Jennifer Francis Senior Scientist, Woods Hole Research Center: It is true that there are often (but not always) two jet streams in each hemisphere. The hypothesis related to Arctic warming causing weaker zonal winds of the jet refers to the POLAR jet. This flow is driven primarily by the temperature difference between the Arctic and middle-latitudes. The features headlined in this story, however, are a product of the SUB-TROPICAL jet, which is driven mainly by temperature differences between the tropics and middle-latitudes. The upper-level tropical atmosphere is also warming faster than most other places, which is increasing the temperature difference and thus contributing to a STRONGER sub-tropical jet [and not a weaker, wavier jet as this article suggests]. Clifford Mass, Professor of Atmospheric Sciences, University of Washington: This is total nonsense. Flow often crosses the equator. The cross-equator flow identified by Scribbler and Beckwith is not between mid-latitude jet streams, as claimed. The analysis is making mistakes that even one of my junior undergrads would not make. [this comment was originally published in a rebuttal to the bloggers’ claims in The Washington Post] Ken Caldeira Senior Scientist, Carnegie Institution for Science: This is an odd story because the subhead and the second quotes dismiss the central claim as being “total nonsense”. So, the story seems more-or-less accurate: “A couple of people make a strong claim that is likely to prove false and a bunch of other people denounce the claim as total nonsense”. The question therefore is not so much the accuracy of the story, but of the editorial decision to publicize something that was likely to prove total nonsense. Further, the story reports on a blog post. I do not see any reference to any peer-reviewed paper. So again, the question is why is The Independent giving so much play to what appears to be an erroneous blog post? I do not see this piece so much as a failure of reporting as a failure of proper editorial control. [note that this comment was written after the article was updated with a link to the rebuttal]Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time."
https://science.feedback.org/review/its-official-humans-are-making-the-earth-much-greener-washington-post-chris-mooney/,0.6,"The Washington Post, by Chris Mooney, on 2016-06-27.",,"""Thanks to climate change, the Arctic is turning green""",,,,,"Overall the article accurately reports that increased temperatures and atmospheric CO2, due to human greenhouse gas emissions, are already increasing plant growth in the Arctic region. However, scientists point to some misleading aspects of the article: most problematically, the author leaves open the hypothesis that the increased CO2 uptake by plants in the Arctic could significantly offset future global warming. In reality, scientists already take into account CO2 uptake by plants in climate projections and conclude that Arctic greening is very unlikely to have a significant impact on the global carbon cycle.See all the scientists’ annotations in contextGUEST COMMENTS: Chelsea Little PhD candidate, Eawag, The Swiss Federal Institute for Aquatic Science and Technology: The main message of this article – that the Arctic is greening, and that this trend is caused by anthropogenic climate change – is accurate and well-explained. The author also addresses the complexity of the trend’s potential impacts on the Arctic itself and on global greenhouse gas concentrations. Peter Reich Regents Professor, University of Minnesota: The article is a poster child for a lot of what is wrong with even our “hypothetically” best mainstream press coverage of science and the environment. The article is factually accurate (up to a point) but incomplete. It is true that rising CO2 and longer growing seasons likely will increase LAI [leaf area index] and productivity in certain northern regions, but the article gives the impression (by intentionally or unintentionally conflating northern regions and the rest of the world) that this may be widespread. Additionally, and equally or more problematically, the article is imbalanced in not fully acknowledging that the scale of net positive impacts (in terms of increased carbon gain) in far northern regions will likely only partially offset: carbon losses from high latitude ecosystems (e.g. soil carbon losses from peatlands and permafrost due to decomposition, respiration and/or fire), climate-change induced losses of productivity in the tropics, and climate-change induced losses of carbon from increased wildfires in southern boreal and temperate coniferous forests. Thus the article fails my “objectivity” test in being more about making a news splash than about reporting these important findings accurately framed within the overall broader context.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Ken Caldeira Senior Scientist, Carnegie Institution for Science: Overall, this is an excellent article. It not only reports the key scientific findings but also highlights several key uncertainties. This article nicely balances a description of what we think we know with a description of what we know we don’t know. Overall, I would consider this an exemplary piece of science journalism. My one critique would be the assumption implicit in the reporting that greening is all good. While greening is good for some things, greening can be disruptive to ecosystems. Organisms that were well-adapted to harsher conditions might find themselves at an ecological disadvantage as conditions ameliorate, and thus there will be winners and losers. Thus greening can have adverse consequences for biodiversity. This implicit assumption that greening is good is reflected in the title of the piece, raising the issue of who or what we should ‘thank’ for the greening. Overall, however, this is a thoughtful and nuanced piece of scientific reporting. Jake Weltzin Program Manager, US Geological Survey: Overall a nice description of the state of the science; well-referenced and linked; outlines the uncertainties; describes how this work builds on, but is different from, prior work. Alexis Berg Research Associate, Harvard University: This article reports on a new high-profile study that formally attributes the documented greening of the Arctic to human greenhouse gas emissions. The article correctly places this new research in its context (the greening had been observed before, but not explained) and identifies what is new in the study. However, the author then goes on to discuss the implications of this greening for the carbon cycle, and somehow implies that these results about Arctic greening are new cause for optimism, as greening will be associated with CO2 absorption by the land which will slow down global warming. This whole discussion, in my view, was confused and potentially misleading for readers. The distinction between “greening” and ecosystems being a potential sink/source of carbon is not well presented. Arctic greening is well documented, but whether this means the Arctic is storing more and more carbon (and will keep doing so in the future) is unclear, and a topic of ongoing research. The article also seems to imply that these results are new cause for optimism because the land carbon uptake was somehow not accounted for in climate projections. This is incorrect. It is already well established that the land takes up about 25% of our CO2 emissions. Observations of greening at high latitudes are consistent with our expectations. The land carbon sink is already accounted for in climate change projections. There are some uncertainties, but the issue is mostly whether this sink will persist or decrease – not, as the author implies here, whether it will somehow go up to offset the entirety of human CO2 emissions and associated global warming. The article reports about recent evidence that terrestrial ecosystems are ‘greening’ in response to human activities, principally the increasing atmospheric CO2 concentration. The author presents this ‘greening’ as a new finding while annual global carbon budgets have reported that about 25% of the fossil-fuel emissions have been taken up by the biosphere since the 1960s. Nothing is fundamentally wrong in the article but it is organized in a somewhat misleading way, with a high risk that the title could be taken out of context by “skeptics”. James Renwick Professor, Victoria University of Wellington: This is a very nice article that lays out the recent evidence. It discusses the pluses and minuses of the issue and comes to a balanced conclusion. The article is quite neutral and balanced. It describes the Arctic greening and its attribution to climate change and CO2 increase, also mentioning uncertainties. The article concludes by saying that “researchers do not seem to be arguing that it’s enough to counterbalance the entire human-induced warming trend”. On the contrary, this should be seen as evidence that “we are causing the Earth to change”. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from Chris Mooney; comments and replies are from the reviewers. 1. Increased CO2 concentrations and temperature won’t necessarily increase plant productivity in the future and in all regions (there are other factors controlling plant growth such as nutrient and water availability…) “Earlier this month, NASA scientists provided a visualization of a startling climate change trend — the Earth is getting greener, as viewed from space, especially in its rapidly warming northern regions. And this is presumably occurring as more carbon dioxide in the air, along with warmer temperatures and longer growing seasons, makes plants very, very happy.” Peter Reich Regents Professor, University of Minnesota: The point in the second sentence may be true for areas where longer growing seasons and warmer temperatures do increase productivity, but it is likely false for vast other regions of the world where lack of moisture will outweigh positive impacts of global change on growth. So this sentence right off the bat gives a bit of a misrepresentation by being worded in a way that can be construed as applying globally not just in the far north. Also there is nothing “startling” about this trend – it is exactly as hypothesized for such regions. “This is happening even as the overall warming of the planet may, by lengthening growing seasons and moistening the atmosphere, further stoke plant growth.” Alexis Berg Research Associate, Harvard University: … note that relative humidity over land, near the surface, is projected to decrease with global warming (i.e., humidity increases more slowly than temperature over land). This has been observed in the past 10-15 years (although the role of variability is still unclear). So “moistening of the atmosphere”, as far as vegetation is concerned, is not accurate (at least globally). See: https://www.climate.gov/news-features/understanding-climate/2013-state-climate-humidity “The key question then becomes how much this process can offset overall global warming over time. And that’s quite unclear. “ James Renwick Professor, Victoria University of Wellington: Exactly. While the “greening” via extra plant growth could help put a brake on climate change, it depends on plants having enough water, and temperatures they thrive in. Neither of these are guaranteed in future, and the greening could easily become browning as the years pass. The overall effect on atmospheric concentrations of CO2 is likely to be small. “He said he is not sure to what extent the greening trend will continue, as “disturbances” like wildfires might counteract it, or plants may become “acclimated to this kind of high temperature”” The Duke FACE [free-air CO2 enrichment] experiment also showed that it is not clear whether nutrient availability will continue supporting high rates of plant productivity despite higher atmospheric CO2 concentrations. 2. Arctic greening won’t offset much of global warming. The global carbon uptake by biomass (plants) is a well-known carbon sink and it is unclear yet whether this sink will remain effective in the future. “It is clear, then, that greening is emerging as a factor with the potential to blunt some of the worst impacts of human greenhouse gas emissions.” Chelsea Little PhD candidate, Eawag, The Swiss Federal Institute for Aquatic Science and Technology: In fact, experts agree that the greening of the arctic is unlikely to even offset the increased carbon release from the arctic itself (much less the rest of the world) in a changing climate, for instance by permafrost melting: The figure above is from a 2016 study that was authored by 100 expert researchers in various fields of arctic climate research, which concludes: “Our study highlights that Arctic and boreal biomass should not be counted on to offset permafrost carbon release and suggests that the permafrost region will become a carbon source to the atmosphere by 2100 regardless of warming scenario.” “Still, the trend is already prompting more optimistic assessments of our climate future in some quarters. Arctic greening was recently cited, in a major report by the U.S. Geological Survey, as the central reason that the state of Alaska, despite worsening wildfires and more thaw of permafrost, might still be able to stow away more carbon than it loses over the course of the 21st century.” Alexis Berg Research Associate, Harvard University: a) This is highly uncertain, because, as discussed, the future of the greening trend is unclear b) it is only for Alaska, and is unlikely to make a significant difference for “our climate future” as the author mentions. c) even if it could be generalized to the entire Arctic, or the entire land, it is no cause for “optimism”: as discussed above, the land is already a carbon sink. It might remain one in the future, despite climate change, but the risk is actually that it decreases and leaves us with more of our emissions accumulating in the atmosphere. “climate change skeptics and contrarians … have long contended that global warming won’t be all bad, and that plants might help offset any global warming trend.” It is not only a skeptic’s argument: the land biosphere does offset part of the warming by taking up 25% of emissions. However, the uncertainty in the durability of this pattern is very large with no clear consensus between earth system models used in the IPCC latest assessment report, see Figure below: From Friedlingstein et al (2014) Uncertainties in CMIP5 Climate Projections due to Carbon Cycle Feedbacks, Journal of Climate “But thus far, researchers do not seem to be arguing that it’s enough to counterbalance the entire human-induced warming trend.” Alexis Berg Research Associate, Harvard University: Of course not. This sentence is highly misleading. As indicated above, the land carbon sink is a well-established phenomenon, not a new theory based on new observations related to Arctic greening and that somehow scientists would now be debating to know whether it will offset global warming entirely. Nobody is even talking about that. The issue is whether the current carbon sink (25% of our emissions) will maintain itself or decrease. The “land sink” offsets about 25% of fossil-fuel emissions annually*. The long-term durability of the sink is debatable as it may be threatened by simultaneous enhancements of soil respiration due to warmer temperatures and more substrate availability (permafrost thaw in particular) but with a large climate-driven variability. *data source: www.globalcarbonproject.org Jacqueline Mohan, Associate Professor, University of Georgia In terms of ecosystems being a carbon sink/storage or source to the atmosphere, it is essential we consider soils and soil microbes. The majority of Arctic ecosystem carbon is stored in the SOILS. With enhanced plant productivity, there is more “microbial food” in the form of organic carbon from plants going to the soils. More microbial food means more microbial metabolism/decomposition of organic carbon to CO2, which is an important SOURCE of carbon (CO2) to the atmosphere with a climate warming effect. To understand what is going on with Arctic ecosystem-climate interactions, we need to know what is going on with ecosystem respiration (C source to atmosphere) not just productivity (C sink from the atmosphere and the topic of the article on increasing “greeness”). In ecosystem ecology there is a finding of a “priming” effect on soil microbial C decomposition, where a small amount of yummy, labile C (the new green stuff coming from plants) can stimulate the decomposition and release to the atmosphere of very old, less yummy recalcitrant forms of C that had been stored in soils for a long time. This could actually result in more carbon being released to the atmosphere by Arctic ecosystems than they took from the atmosphere to support the measured enhancement in greenness. 3. The fact that the Arctic is “greening” has been documented before, but the attribution of this trend to human activities is new. “new research in Nature Climate Change not only reinforces the reality of this trend — which is already provoking debate about the overall climate consequences of a warming Arctic — but statistically attributes it to human causes, which largely means greenhouse gas emissions (albeit with a mix of other elements as well).” Alexis Berg Research Associate, Harvard University: That’s a good summary of what’s new in this study: Arctic greening had been documented before, its causes had been discussed, but this is the first study to formally attribute this greening trend to human gas emissions. Note that trends in surface temperature and in some aspects of the hydrological cycle (e.g., precipitation, evaporation) have been detected and attributed similarly; this is the first study to do so with vegetation trends (which appear closely related to temperature trends, though). Chelsea Little PhD candidate, Eawag, The Swiss Federal Institute for Aquatic Science and Technology: While the NASA project is a wonderful visualization with impressive details and scale, the trend of Arctic greening is not startling to scientists. Researchers have been studying the increase in plant growth in the arctic for well over two decades at this point. The author notes this later in his article, but framing the pattern as surprising for the lede is somewhat disingenuous. Whether the trend is slowing or reversing itself, why some areas are browning rather than greening, or what the long-term consequences might be are still very much debated, but the pattern itself is extremely well-established. Here is some of the previous work detailing the trend: “Increased plant growth in the northern high latitudes from 1981 to 1991” R. B. Myeni et al, “Greening of arctic Alaska, 1981-2001” Gensuo Jia et al “Vegetation greening in the canadian arctic related to decadal warming“, by the same authors also using satellite data, this time from 1982-2006 “Divergent Arctic-Boreal Vegetation Changes between North America and Eurasia over the Past 30 Years“, Jian Bi et al, showing greening also in the European and Russian Arctic"
https://science.feedback.org/review/great-barrier-reef-perish-2030s-andrew-freedman-mashable/,1.0,"Mashable, by Andrew Freedman, on 2016-04-29.",,"""Great Barrier Reef may perish by 2030s...""",,,,,"This Mashable article reports on preliminary research that finds that the ongoing coral bleaching event in the Pacific is mainly due to human-caused global warming, and that if global warming proceeds as currently expected, “large parts” of the Great Barrier Reef could die by the mid-2030s. Six scientists have reviewed the article and conclude that overall it is accurate and in agreement with the science. The title, however, was pointed out to be somewhat exaggerated. Scientists expect that coral reefs may perish by the 2030s, yet the “Great Barrier Reef” is an ecosystem of many different species that are variously resilient to climate change. To be clear, catastrophic impacts are predicted for coral reefs, but this does not necessarily mean the entire Great Barrier Reef will be devastated. See all the scientists’ annotations in contextGUEST COMMENTS: The article reflects the current state of knowledge in this area. While it may sound alarming (even alarmist) that the world’s most biologically diverse marine ecosystem may be largely eliminated over the next 20-30 years, this is the conclusion and scientific consensus to be found in Chapter 30 and other places of the latest Intergovernmental Panel on Climate Change report (IPCC). It is also the consensus conclusion of the major scientific bodies and science community that study coral reefs (e.g. International Society for Reef Studies report). Jon Day PhD candidate, ARC Centre of Excellence for Coral Reef Studies, James Cook University: The article focuses solely on increasing ocean temperatures whereas the Great Barrier Reef (GBR) is currently threatened by multiple pressures – however, none of the other pressures are mentioned. It builds on the erroneous headline that “..93% of the GBR has already been devastated by bleaching” – whereas the media release from the ARC Centre for Coral Reef Studies explained why this was not a true summation of the recent bleaching situation. This article also gives readers the (false) impression that the entire Great Barrier Reef will be devastated within decades; whereas the article should have clarified it was referring to the coral reefs which, whilst a critical part of the GBR, comprise around 10% of the entire area.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. The article is an accurate description of an unpublished study that models the effect of anthropogenic ocean warming on ocean temperatures and coral bleaching. It is a nice description of the science, context, warming impacts, and basic ecology of the system. Minor points off for a somewhat exaggerated headline. (Note, the faculty are at three academic research institutions in Australia, not at the ARC, which is the national funding agency). James Renwick Professor, Victoria University of Wellington: This is a very good and readable article. I can find very little to quibble with over the description of the science. Excellent science, communicated clearly. Sarah Perkins-Kirkpatrick Research Scientist, Climate Change Research Centre, The University of New South Wales: I was an author on the scientific study this article is reporting on. The article is sticking to our findings very accurately. It also does a nice job of presenting the state of knowledge in the field.Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time.Key Take-aways : The statements quoted below are from Andrew Freedman; comments and replies are from the reviewers. 1. Coral reefs around the globe are threatened with extinction this century due to climate change that causes the oceans to warm and become more acidic “The projection that much of the Great Barrier Reef could perish within the next few decades could turn out to be too pessimistic, since other research has shown that some species of corals are surprisingly resilient to the stress from changing ocean temperatures.” Ken Caldeira Senior Scientist, Carnegie Institution for Science: Whether it is two decades or four decades does not make much of a difference to people living 100 years from now. It is clear that if we do not curtail emissions dramatically and soon, coral reefs around the world will be gone. I would like to add to Ken’s point here. We are already – and have been for some time – into dangerous climate change when it comes to coral reefs and hundreds of millions of people that depend on them. The first global mass coral bleaching (NB: reef scale and regional coral bleaching has been reported since the early 1980s and not before) occurred in 1998 and saw the death of an estimated 16% of reef building corals from across the planet (which sounds small until you appreciate that this is a global average!). While it is too early to speculate at this point, the fact that we now have much warmer seas underpinning the current global disturbance to temperature patterns (plus the much more severe event in Australia) suggests that we will have a much greater mortality at the end of 2016 than what we saw in 1998. “The analysis’ findings dovetail with other research that has predicted the mass die-off of coral reefs around the planet by the year 2050, as waters warm and exceed the tolerance level of many coral reef systems.” This is true. This statement refers to the study I published in 1999 (Climate change, coral bleaching and the future of the world’s coral reefs) which brought climate projections together with the known tolerances of reef building corals and specifically proposed that the conditions that cause serious bleaching today would occur every 1-2 years by 2040-2050.[…] The important point here is that anything more frequent than 10-15 years in terms of mass coral bleaching events will overwhelm regeneration, which normally takes this long to occur. That is, coral reefs go downhill well before bleaching conditions become as frequent as every 1-2 years. “a new study by scientists at the Australian Research Council finds that the ongoing bleaching event is mainly due to human-caused global warming, and that if global warming proceeds as currently expected, “large parts” of the Great Barrier Reef could die by the mid-2030s.” Ken Caldeira Senior Scientist, Carnegie Institution for Science: We published a paper some years ago projecting that by mid-century, no coral reefs would be sustainable (Silverman et al 2009: Coral reefs may start dissolving when atmospheric CO2 doubles). It is thus not surprising to see the failure of large areas of reef before that date. “Great Barrier Reef may perish by 2030s” Ken Caldeira Senior Scientist, Carnegie Institution for Science: This word ‘may’ is obviously key. The question is: what is the likelihood. 2. The current global bleaching event is unprecedented; it is due to the combined influence of global warming and El Niño “The ongoing global bleaching event is the longest-lasting one ever observed, and only the third ever seen. It has occurred during the warmest year on record, which occurred in 2015, and the two most unusually mild months on Earth, which took place in January and February, respectively.” It should be emphasized to the readers that mass coral bleaching first turns up in scientific records in the early 1980s – with no reports prior to that. Over time, mass coral bleaching and mortality has expanded in frequency and severity, with three truly global events being recorded so far – 1998, 2010, and 2016. The apparent shortening of the interval between global events is of great concern and suggests that anything we can do now to avoid further increases in carbon dioxide and other greenhouse gases in the atmosphere will save very substantial amounts in lost income and livelihoods from subsistence as well as industries such as fishing and tourism. This is an issue of food security – the effects of which are already occurring and which are growing more serious by the day. 3. Ocean warming is one of many human pressures that are stressing coral reefs (eg pollution, acidification…) “Australia’s Great Barrier Reef is one of the world’s greatest reservoirs of biodiversity. A World Heritage site, it is currently under assault from unusually hot ocean temperatures,” Jon Day PhD candidate, ARC Centre of Excellence for Coral Reef Studies, James Cook University: The 2014 Outlook Report published by Great Barrier Reef Marine Park Authority, the agency responsible for managing the Great Barrier Reef (GBR), clarifies that the GBR is currently faced with many pressures, of which climate change is only one. Poor water quality from land-based runoff, damage from cyclones, ocean acidification, Crown-of-Thorns starfish, dumping of dredge spoil, etc, are among a multitude of pressures which are cumulatively impacting on the GBR, and particularly upon coral reefs. Ken Caldeira Senior Scientist, Carnegie Institution for Science: Note that there is also a possibility that ocean acidification is contributing stress to coral reef systems, making them more susceptible to bleaching from high seawater temperatures. Note: The article builds on another Mashable article (“Coral bleaching has devastated 93% of the Great Barrier Reef”) whose title is misleading “Coral bleaching has devastated 93% of the Great Barrier Reef” Jon Day PhD candidate, ARC Centre of Excellence for Coral Reef Studies, James Cook University: This headline stating that “bleaching has devastated 93% of the GBR” is misleading as I explained in a recent article in The Conversation: “It is important to recognise that if bleaching was observed on a reef, this does not mean a particular reef has entirely bleached. […] Perhaps the more accurate way to frame the results (and indeed the wording used in the media release) is to say that only 7% of the coral reefs across the Great Barrier Reef have completely avoided bleaching.”"
https://science.feedback.org/review/bjorn-lomborg-overheated-climate-alarm-wall-street-journal/,-1.3,"The Wall Street Journal, by Bjorn Lomborg, on 2016-04-06.",,"""An Overheated Climate Alarm""",,,,,"On 4 April 2016 the US Global Change Research Program released a comprehensive overview of the impact of climate change on American public health. In an op-ed in the Wall Street Journal, Bjorn Lomborg criticizes the report as unbalanced. Ten scientists analyzed the article and found that Lomborg had reached his conclusions through cherry-picking from a small subset of the evidence, misrepresenting the results of existing studies, and relying on flawed reasoning.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Aaron Bernstein Associate Director of the Center for Health and the Global Environment, Boston Children’s Hospital, Harvard: While it’s true that cold may kill more people today than heat, Lomborg’s assertion that climate change will result in fewer overall deaths in the U.S. this century from extreme temperatures is not supported by available evidence. The citations in the report, which Lomborg himself dismisses, substantiate this claim e.g. Mills, David, et al. “Climate change impacts on extreme temperature mortality in select metropolitan areas in the United States” in Climatic Change. Lomborg largely conflates U.S. with global assessments. His logic, from a public health perspective, is also deeply troubling and fails, at first pass, the maxim of “first do no harm”. Beyond this, adaptive capacity to climate extremes is no easy feat and as several past extreme heat events have shown, such as the European heatwaves of 2003 or 2010, the consequences reverberate beyond mortality in those directly exposed. Heatwaves promote wildfires, crop losses, food price spikes and conflicts. Antonio Gasparrini Senior Lecturer, London School of Hygiene and Tropical Medicine: My review is limited to the part of the article that describes the results of the study published in The Lancet, which I first-authored. The interpretation provided in the article is misleading, as our study is meant to provide evidence on past/current relationships between temperature and health, and not to assess changes in the future. In addition, the study does not offer a global assessment, and it is limited to a set of countries not representative of the global population. Alexis Berg Research Associate, Harvard University: Bjorn Lomborg disputes the notion, presented in a recent national assessment report, that global warming will increase the number of temperature-related deaths in the US. To do so, he carefully picks studies and uses flawed reasoning. Instances of faulty reasoning include Lomborg’s interpretations of the facts that i) cold-related deaths currently outnumber heat-related ones and ii) migration patterns in the last decades indicate that people are generally moving to the warmer, Southern part of the US. However, i) does not imply that warmer temperatures will reduce deaths: what matters is the sensitivity of the death-risk to a change in temperature, and that appears to be higher for heat than for cold; as for ii), migration patterns are not driven only by climate, and probably account for future climate change even less so. While Mr. Lomborg’s single focus on deaths directly related to temperature could imply that it is the only thing that matters, it clouds out (whether on purpose or not) all the other impacts expected from global warming: impacts on ecosystems, agriculture, water resources, sea level rise, etc. Those other impacts are also expected to have detrimental effects, if not directly on the lives or deaths of Americans, at least on their welfare and on America’s prosperity. Stephan Lewandowsky Professor, University of Bristol: Mr Lomborg points to a skewed and highly selective sample of the literature and ignores many other well-established findings that would undermine his argument. For example, the article ignores the recent finding that economic productivity declines with increasing temperatures past a fairly cool inflection point, and that this relationship remains unchanged even after considerable time for adaptation has elapsed. The article also ignores the adverse effects of climate change on agricultural production; the demonstrable relationship between heat and migration; the association between heat and interpersonal violence at all scales; the fact that unmitigated climate change will eventually make parts of the planet uninhabitable due to the increase of temperatures beyond the life-threatening threshold of 35C (wet bulb temperature, not dry temperature). Bizarrely, for an article concerned with the health effects of climate change, Mr Lomborg also fails to mention the demonstrable health benefits that are associated with cutting carbon emissions due to a reduction in pollution-related mortality. Unfortunately, therefore, the article fails to inform but instead misleads the readership by an extremely selective reporting of the literature. Steven Sherwood Professor, University of New South Wales: The article raises legitimate issues but its key point that cold kills more people than heat is misleading, because heat deaths will skyrocket once global temperature has risen significantly while the benefits on the cold side will decline. Indeed there is a strict limit to human tolerance of heat and humidity, that may be approached in some regions within a century and would cause severe stresses. Philip Staddon Lecturer/Visiting Scholar, The Open University, Xi’an Jiaotong-Liverpool University: Lomborg is using scientific ‘language’ to suggest that climate change will have insignificant health impacts; this goes against a vast body of evidence. The notion that benefits from warmer winters could be more important than risks from hotter summers in terms of human health is plain wrong. For once, the US administration is taking health impacts of climate change seriously, and it is particularly unhelpful to attempt to confuse the public on this issue. David Mills Managing Analyst, Stratus Consulting: The article claims the new U.S. Global Change report overlooks the evidence about the relative significance of mortality attributed to cold (and the cold season) relative to heat (and the hot season) while in reality, it is included (see Sections 2.5 and 2.6). Similarly, Lomborg uses selective representation of published literature and puts the emphasis on studies outside the U.S., while the new report specifically notes it focuses on reviewing U.S. based studies. Katrin Meissner Professor, University of New South Wales: This article is cherry-picking and presents scientific results in a misleading way. Rasmus Benestad Senior scientist, The Norwegian Meteorological institute: I think the article misrepresents statistics and cherry picks some facts to support its position while ignoring relevant ones. There may be some validity in some of the points. Overall, the message is very dubious. For the interested reader, here is an insightful discussion on the topic of how climate change threatens U.S. population’s health. Michael Brauer Professor, The University of British Columbia: The article is selective in its interpretation of the temperature-mortality relationship. It is correct that both cold and warm temperatures kill and that, at present, cold kills more than heat but that does not imply that future warming will lead to fewer cold-related deaths than any increase in heat-related deaths, these relationships are complex and non-linear. It also discusses one part only of a comprehensive assessment to argue that the whole assessment is incorrect/invalid. This is biased. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time.Key Take-aways : The statements quoted below are from Bjorn Lomborg; comments and replies are from the reviewers. 1. Climate change impacts on health are not limited to just cold and heat-related deaths but also include air quality, extreme events, diseases carried by parasites… “Higher temperatures, we’re told, will be deadly—killing “thousands to tens of thousands” of Americans” Alexis Berg Research Associate, Harvard University: Whether this is on purpose or not, Mr. Lomborg’s immediate focus on the part of the report dealing with temperature-related deaths makes it sound as if this is the only focus of the report. However, the report also deals with air quality impacts, food safety, extreme events, etc. “cold kills many more people than heat.” Kristie Ebi Professor, University of Washington: Mr. Lomborg is confusing seasonal mortality with temperature-related mortality. It is true that mortality is higher during winter than summer. However, it does not follow that winter mortality is temperature-dependent (which summer mortality is). Dave Mills and I reviewed the evidence and concluded that only a small proportion of winter mortality is likely associated with temperature. A growing numbers of publications are exploring associations between weather and winter mortality, with differences in methods and results. The country with the strongest association between winter mortality and temperature is England, which appears in other publications to be at least partly due to cold housing. Winter mortality is lower in northern European countries. Rasmus Benestad Senior scientist, The Norwegian Meteorological institute: This is cherry picking – even if it were true. Climate change is much more than just temperature. It also affects precipitation and the lack thereof – with consequences such as floods, mud slides, droughts, and wildfires. Furthermore, the cold is fairly limited to the high northern latitudes, … and not so many live there, but many more in the warm tropics… These rich countries also have the means to collect statistics. The poor developing countries often lack credible statistics, and I do not believe for a second that we have an estimate of all people who die from heat stress in Asia, Africa, and Latin America. Philip Staddon Lecturer/Visiting Scholar, The Open University, Xi’an Jiaotong-Liverpool University: Lomborg seems unaware of, or more likely is ignoring, the fact that climate change caused by human activities is making the climate not only warmer but more unpredictable: increased intensity and frequency of extreme weather events including drought, heavy downpours, heat waves… “In pushing too hard for the case that global warming is universally bad for everything, the administration’s report undermines the reasonable case for climate action.” Alexis Berg Research Associate, Harvard University: As seems to always be the case with Lomborg (cf his previous WSJ’s article reviewed by Climate Feedback), he picks up a few studies that support his position. Note, first, that the report’s claim about projected heat-related deaths outweighing cold ones applies to the US: different regions might have different responses… Second, when reviewing the literature on the topic, the IPCC report indicates (WGIIAR5-Chap11, p.721): “it is not clear whether winter mortality will decrease in a warmer, but more variable, climate (Kinney et al., 2012; Ebi and Mills, 2013). Overall, we conclude that the increase in heat-related mortality by mid-century will outweigh gains due to fewer cold periods, especially in tropical developing countries with limited adaptive capacities and large exposed populations” So the US report does not appear wildly at odds with the literature on the topic, or to be “pushing too hard”. Also, it does not say that warming is universally bad, just that the bad outweighs the good on this particular topic. 2. It is not obvious that winter-death will decrease due to climate change, contrary to Lomborg’s claim “…climate change will also reduce the number of cold days and cold spells. That will cut the total number of cold-related deaths.” Philip Staddon Lecturer/Visiting Scholar, The Open University, Xi’an Jiaotong-Liverpool University: The assertion that warmer winters = less mortality is a schoolboy error. Indeed everyone knows that European countries with warmer climates and milder winters actually have MORE not LESS winter mortality; principally due to adaptation. The current numbers of winter mortality may well be higher than summer heat wave mortality in many temperate to northern countries, however what is crucially important is that evidence points to significant increase in summer heat related mortality and no or very little change to winter mortality as a result of climate change. Katrin Meissner Professor, University of New South Wales: A recent paper by Kinney et al. (Winter season mortality: will climate warming bring benefits?) suggests that reductions in cold-related mortality under warming climate may be much smaller than some have assumed. Kinney and colleagues analyzed excess winter mortality across multiple cities and over multiple years within individual cities. They found that excess winter mortality was no lower in warmer vs. colder cities, suggesting that temperature is not a key driver of winter excess mortality. In addition, variability in daily mortality within cities was not strongly influenced by winter temperature. Kristie Ebi Professor, University of Washington: There is very limited scientific support for the claim that reducing the number of cold days (by which he apparently means winter) will reduce the number of cold-related deaths. Again, this is assuming winter mortality is temperature-dependent; an assumption not verified by research in the US and elsewhere. “The administration’s new report refers to this study … but only in trivial ways, such as to establish the relationship between temperature and mortality.” Antonio Gasparrini Senior Lecturer, London School of Hygiene and Tropical Medicine: As previously noted, [our] study contributes evidence only to ‘direct’ effects of temperature on human health. As a matter of fact, this is likely to represent a minor part of the total excess mortality and morbidity due to a changing climate. 3. Lomborg misrepresents the U.S. Global Change report that he criticizes and he misunderstands the Lancet study that he uses to support his case “Not once does this “scientific assessment” acknowledge that cold deaths significantly outweigh heat deaths.” Alexis Berg Research Associate, Harvard University: That’s not true. Under section 2.5, the report indicates: “A recent analysis of U.S. deaths from temperature extremes based on death records found an average of approximately 1,300 deaths per year from 2006 to 2010 coded as resulting from extreme cold exposures, and 670 deaths per year coded as resulting from exposure to extreme heat. These results, and those from all similar studies that rely solely on coding within medical records to determine cause of deaths, will underestimate the actual number of deaths due to extreme temperatures.” And then further down (my emphasis): “studies based on statistical approaches have found that, despite a larger number of deaths being coded as related to extreme cold rather than extreme heat, and a larger mortality rate in winter overall, the relationship between mortality and an additional day of extreme heat is generally much larger than the relationship between mortality and an additional day of extreme cold.” “Consider a rigorous study published last year in the journal Lancet that examined temperature-related mortality around the globe.” Antonio Gasparrini Senior Lecturer, London School of Hygiene and Tropical Medicine: As the first author of this article, I deem it is worth pointing out that the aim of this study is to establish the association between non-optimal temperature and mortality (in terms of excess deaths) in the recent past, using historical data. The article clearly acknowledges that these results cannot be easily extrapolated to the future, in particular under climate change scenarios, for a series of reasons detailed in the discussion section of the article. For instance, the change in heat and cold-related deaths will depend on changes in future temperature distribution, which is likely to be more complex than a simple upward shift. “The report confidently claims that when temperatures rise, “the reduction in premature deaths from cold are expected to be smaller than the increase in deaths from heat in the United States.” Six footnotes are attached to that statement.” Alexis Berg Research Associate, Harvard University: The report says “The decrease in deaths and illness due to reductions in winter cold have not been as well studied as the health impacts of increased heat, but the reduction in premature deaths from cold are expected to be smaller than the increase in deaths from heat in the United States“. This doesn’t sound over-confident to me; and as for the “footnotes”, there are scientific references to back up that claim, not asterisks leading to fine-print caveats… 4. Excess mortality during cold days does not imply people died from the cold (think influenza…) “In the U.S. about 9,000 people die from heat each year but 144,000 die from cold.” Alexis Berg Research Associate, Harvard University: These numbers are not deaths reported as clinically due to heat or cold. It seems Lomborg computed them from the Lancet study, using percentages given by the study, times the total number of deaths. Kristie Ebi Professor, University of Washington: Where do these numbers come from? According to a review of national health statistics: During 2006–2010, about 2,000 U.S. residents died each year from weather-related causes. About 31% of these deaths were attributed to exposure to excessive natural heat, heat stroke, sun stroke, or all; 63% were attributed to exposure to excessive natural cold, hypothermia, or both; and the remaining 6% were attributed to floods, storms, or lightning. This statement also confuses seasonal mortality with mortality from extreme events. As noted in Ebi and Mills, this distinction is important for understanding what could happen with climate change. Philip Staddon Lecturer/Visiting Scholar, The Open University, Xi’an Jiaotong-Liverpool University: In the UK for example, the evidence now shows NO strong link between how cold a winter is and how many deaths occur. Sure the link was very strong up until the 1970s, but Lomborg might be aware that since the 1950s there have been massive improvements in building, heating, aid to the poorest, healthcare. How winter temperatures affected mortality in the 50s is no longer relevant. The key driver for annual variation in winter mortality in rich countries now appears to be incidence and virulence of influenza and similar diseases. Antonio Gasparrini Senior Lecturer, London School of Hygiene and Tropical Medicine: As previously noted, the study published in The Lancet contributes little to understanding how these figures will change in the future under scenarios of climate change. In particular, it is difficult to ascertain from these results if the supposed decrease in cold-related deaths will offset the supposed increase in heat-related mortality. “cold deaths actually occur during moderate temperatures” Rasmus Benestad Senior scientist, The Norwegian Meteorological institute: This suggests that the dependency is not linear, and there is a multitude of factors involved. Hence, “cold deaths” may be a misnomer. The temperature is a moderator combined with standard of living, life-style diseases, pollution, and poverty, in addition to accidents and other weather conditions… “The Lancet researchers found that about 0.5%—half a percent—of all deaths are associated with heat, not only from acute problems like heat stroke, but also increased mortality from cardiac events and dehydration. But more than 7% of deaths are related to cold—counting hypothermia, as well as increased blood pressure and risk of heart attack that results when the body restricts blood flow in response to frigid temperatures.” Alexis Berg Research Associate, Harvard University: I do not want to question the quality of this particular study, but it’s worth looking at how they get such numbers. First, this is a statistical study where they look at data on numbers of deaths and temperatures in various locations: of course, nothing says if, or how, these deaths are really related to temperature (heat or cold). This is an empirical study. Lomborg’s comments suggest that the authors of this study are counting deaths explicitly caused by heat or cold, but this is not the case. Second, they basically fit a temperature-death risk response curve to this data. They then see for what temperature the mortality risk is lowest – and then they aggregate all the deaths below (for cold-related deaths) and above (for heat-related ones) that temperature. Because the temperature of minimum mortality is often high (around 20-25C, or lower 70’s F), for cold-related deaths this leads to integrating the response function (even with low death risks) over much of the temperature distribution. See plots below. The authors indicate as much: “This difference was mainly caused by the high minimum-mortality percentile, with most of the mean daily temperatures being lower than the optimum value.” This methodology also explains why most cold-related deaths appear due to “moderate cold”. This is worth explaining, because I am not sure dying in 15C weather (60F) in Rome or Sydney is really what people will understand when they read about “cold-related deaths”! From Gasparrini et al. figure 1: Exposure–response associations as best linear unbiased prediction (with 95% empirical CI, shaded grey) in representative cities of the 13 countries, with related temperature distributions. Solid grey lines are minimum mortality temperatures and dashed grey lines are the 2.5th and 97.5th percentiles. RR=relative risk. The other thing that is easy to see is that the risk curve generally increases slowly towards cold temperature, but a lot more steeply past high temperatures. So even if one agrees with how this study classifies and counts “cold deaths”, the fact that they outnumber heat deaths, in absolute numbers, does not necessarily mean that increasing temperatures will reduce deaths: based on these plots, it could well be that warming will reduce cold-related deaths less than it increases heat-related ones. And indeed, this is what the studies about future projection of temperature-related deaths that they cite, and that Lomborg discusses, do find. 5. Southern states will likely become less attractive due to impacts of climate change “Consider where they move. Migration patterns show people heading for warm states like Texas and Florida, not snowy Minnesota and Michigan.” James Renwick Professor, Victoria University of Wellington: This focuses on average climate rather than on extremes, and such patterns of migration are based on our knowledge of the past. As the frequency of extreme hot days increases, as the number of extreme hurricanes increases, and as sea levels rise, people may find that Florida is not so attractive after all. Alexis Berg Research Associate, Harvard University: People don’t like the cold, they like sunshine and warmth, and (supposedly as a result, according to Lomborg), they move to the South: does Lomborg really want us to deduce from that that global warming will thus be good for us – even simply in terms of temperature-related deaths? That’s not reasonable. First, while people have indeed generally been moving from the North(-East) to the South over the last decades, it’s not only because of “better climate”: quoting this article by the Washington Post, “Several long-term trends dating as far back as the 1960s are behind this larger pattern. The rise of air conditioning and interstate highways have made once-sleepy (and sweltering) Southern cities more appealing. And, over the same time, the decline of industrial jobs in the Midwest and Northeast have pushed people out. Cheap housing during the boom years also drove growth in states such as Arizona and Nevada“. I think that is already much more reasonable than saying that people move South only because they know they are less likely to die from cold exposure there. Second, people may be moving there right now partly because of climate, and that may indeed be a “smart” move because, TODAY, indeed, current cold-related deaths outnumber heat-related deaths. However, even supposing that this is a significant factor in their decision process, it’s not clear that they are also thinking about future warming. So the fact that people are moving there NOW does not even logically imply, as Lomborg would have it, that FUTURE warming will be beneficial – which is the point of interest here. Kristie Ebi Professor, University of Washington: This has more to do with economic factors than weather. If people moved only because of poor weather, why hasn’t everyone left Northern Europe?"
https://science.feedback.org/review/washington-post-chris-mooneys-earth-no-parallel-66-million-years/,1.5,"The Washington Post, by Chris Mooney, on 2016-03-21.",,"""What we’re doing to the Earth has no parallel in 66 million years, scientists say""",,,,,"Chris Mooney reports on a new scientific study that shows the current rate of increase of carbon dioxide in the atmosphere is unprecedented in the record of the last 66 million years. The seven scientists who reviewed the article confirmed that it is accurate and insightful. While a significant die-off of oceanic species coincided with the rapid increase in CO2 that happened around 55 million years ago, the rate of carbon release from human activities today is at least ten times as fast, suggesting the negative consequences on marine life could be greater this time.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. The Washington Post article refers to an article published in Nature Geoscience. In the original scientific article, the authors use an elegant model-data comparison twist to evaluate whether the carbon release was rapid enough to produce a detectable lag in the climate response to the initial carbon release. Although the publication is rather technical, the Washington Post article effectively highlighted the primary message: according to the authors’ best estimate of the carbon release rate, humans might well release carbon ten times more rapidly than what likely happened during the PETM (Palaeocene–Eocene Thermal Maximum). It sadly implies that even the PETM, a massive warm climatic excursion, might not be harsh enough to represent an analogue for future climate change, as the Washington Post rightfully points out. The article does a very good job in working out the main message of the original scientific paper in an understandable way without oversimplification. The statements are generally correct, except maybe at one point, where it is said that “the researchers used a deep ocean core of sediment”. The sediment core is actually not from the deep ocean but from a rather shallow continental margin site with a high accumulation rate, if I get it right. But this is a minor detail, the main story is conveyed very nicely in this article. Ken Caldeira Senior Scientist, Carnegie Institution for Science: Overall, the article seems to me to be a sound representation of the underlying work. Further, the underlying work appears to be sound. Overall, a well done piece. We need a lot more science reporting of this quality. Katrin Meissner Professor, University of New South Wales: This is a well written and accurate article. Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: I see no problems with this article. It’s a pretty fair representation of one of the key findings of a new paper. Chris Mooney does a great job of placing the results of this study into a modern context. His statements are well supported by existing peer-reviewed literature. Alexis Berg Research Associate, Harvard University: As far as I can tell, this article accurately reports on a recent paleoclimate study investigating the PETM event and the rate of carbon release during that event. The article conveys the study’s conclusion accurately, i.e., that current, man-made rates of carbon release into the atmosphere are unprecedented. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : 1. Past changes in Earth’s climate have been associated with mass extinctions “about 56 million years ago … The planet proceeded to warm rapidly, at least in geologic terms, and major die-offs of some marine organisms followed due to strong acidification of the oceans.”Ken Caldeira Senior Scientist, Carnegie Institution for Science: The event was a “strong acidification” event relative to changes that ordinarily occur over geologic time but it was a weak event compared to what our modern industrial society is threatening to produce. If anything, Chris Mooney is erring on the side of downplaying risks from ocean acidification by saying that “major die-offs” were associated with a “strong acidification” event, when in fact they have been associated with events that are far weaker than we will produce with continued burning of coal, oil, and gas. Katrin Meissner Professor, University of New South Wales: There are several potential causes for the benthic extinctions that are seen in sediment cores. In addition to acidification, abrupt warming of bottom waters, decrease in dissolved oxygen and a potential decrease in food availability (raining down from surface layers) have been put forward in the past (e.g. Thomas [2003] Extinction and food at the seafloor…; Thomas [2007] Cenozoic mass extinctions in the deep sea…; Sluijs et al. [2007] The Palaeocene–Eocene Thermal Maximum super greenhouse…; McInerney and Wing [2011] The Paleocene-Eocene Thermal Maximum: A Perturbation of Carbon Cycle, Climate, and Biosphere with Implications for the Future). 2. Humans are now releasing carbon dioxide at about 10 times faster than the most rapid event of anytime in at least the past 66 million years “We’re putting carbon into the atmosphere at an even faster rate than happened back then.”Lee Kump Professor, PennState University: We are now exceeding by an order of magnitude the rate of carbon release during one of the most remarkable global warming events in Earth’s history. “In contrast, humans are now emitting about 10 billion tons annually — changing the planet much more rapidly.” Alexis Berg Research Associate, Harvard University: This is the current rate, but it’s worth pointing out that this rate is the result of exponential growth over the last decades, and that it was “only” 1-2 billion tons in the 50’s, for instance. In drawing the analogy with the PETM, one may also wonder how long the current rates can be sustained – if anything, compared to the 4,000 years of the PETM – given that such emissions are most likely unsustainable over the long-term, either because of fossil fuel availability constraints, or because of the adverse feedback of climate change on human societies."
https://science.feedback.org/review/scientists-are-exaggerating-carbon-threat-to-reefs-and-marine-life/,-2,"The Australian, The Times, by Ben Webster, on 2016-03-01.",,"""Scientists are exaggerating carbon threat to marine life""",,,,,"Ben Webster reports that the threat posed by ocean acidification to marine life is “exaggerated”. The article, written for The Times and republished in The Australian, is based on an interview by Dr Howard Browman, editor of a special issue on ocean acidification, who claims that Webster quotes him in a misleading way. The article is not representative of the state of scientific knowledge.See all the scientists’ annotations in contextGUEST COMMENTS: Howard Browman Principal Research Scientist, Norwegian Institute of Marine Research: The Times article is not representative of the message that I tried to give the journalist during the interview – that is, the message presented my introduction to the special issue in which I state clearly and explicitly that ocean acidification IS happening and WILL have effects. After reading my introduction, and the articles in the special issue, readers can come to their their own conclusion about whether the journalist worked carefully, conscientiously and impartially to help me accurately spread its messages. I spoke with Ben Webster of The Times in a 30-minute phone call and explained that the objective of the special issue he was reporting on was to introduce more balance into the topic of Ocean Acidification. He cherry-picked our conversation and presented phrases out of context – seemingly in order to be sensational – despite the fact that I told him that the press was part of the “exaggeration” problem. For example, the quoted phrase “inherent bias” in the first paragraph is not the same as the “publication bias” that I refer to in my introduction. Further, my introduction does not say that the existing literature is “exaggerating” the effects of ocean acidification, but that more careful interpretation is required. Finally, I am not saying that the special issue overturns previous literature on the topic, as the Times suggests, but that they should be taken together, in balance. Very disappointing.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Ken Caldeira Senior Scientist, Carnegie Institution for Science: The main problem with this article is that it quotes a single source (Dr. Browman) who has views that differ from much of the scientific community. The author of this article did not interview anyone that Dr Browman is criticizing. Note: “my comments were made before I learned that Dr Howard Browman felt his views were misrepresented in the article”. (added on Mar. 4 2016) Jean-Pierre Gattuso Research Professor, CNRS, Université Pierre et Marie Curie and IDDRI: This article brings together a series of inaccurate and misleading statements on the science of ocean acidification. Adam Subhas PhD candidate, Caltech: This article misses some major intellectual points about ocean acidification, thanks to what seems to be a willful misunderstanding and misquoting of an interview with Dr. Browman on an Ocean Acidification special issue journal. Mark Eakin Scientist, Coordinator of NOAA’s Coral Reef Watch, National Oceanic and Atmospheric Administration: The reporter uses inflammatory language and cherry-picks parts of the paper to create a story that is basically untrue. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time.Key Take-aways : 1. Research shows that Ocean Acidification has serious consequences for marine life “More than half of the 44 studies selected for publication found that raised levels of CO2 had little or no impact on marine life, including crabs, limpets, sea urchins and sponges”Jean-Pierre Gattuso Research Professor, CNRS, Université Pierre et Marie Curie and IDDRI: This is meaningless… it is not unexpected that several papers published in the issue showed little or no impact because the call for papers specifically welcomed such contributions. The bias is therefore very high. I recommend using the unbiased dataset investigated by Kroeker et al. (2013). It does demonstrate negative impacts on some processes and groups of organisms. Kroeker K. et al., 2013. Impacts of ocean acidification on marine organisms: quantifying sensitivities and interaction with warming. Global Change Biology 19:1884-1896. Adam Subhas PhD candidate, Caltech: It is crucial to understand exactly which species are and aren’t affected by Ocean Acidification, as that will determine how ecosystems will change through time. I will also point out that if this figure is correct, and 50% of organisms are unaffected by Ocean Acidification, 50% of organisms are affected by Ocean Acidification, which is a HUGE amount of marine life. It also neglects the fact that reefs themselves are most definitely affected, which creates and maintains the habitat for many of these other organisms in the first place. “The term ocean acidification was also a misnomer, he said, because it suggested that the oceans could become acidic instead of alkaline.”Ken Caldeira Senior Scientist, Carnegie Institution for Science: This is like saying that it is wrong to say the Arctic is warming because it is still cold. ‘Warming’ and ‘acidifying’ both refer to a direction of change and do not specify the state of the system. This claim about a misnomer is based on a misunderstanding of how words are used. “The oceans will never become acid because there is such a huge buffering capacity in the oceans. We simply could never release enough CO2 into the atmosphere to cause the pH to go below 7 [the point in the pH scale at which a solution becomes acidic].”Adam Subhas PhD candidate, Caltech: This statement sets up a false notion about the pH balance of the oceans. In fact, the global ocean is, on weighted average, very close to (but just above) 7, which is controlled by many factors including atmospheric CO2 changes, but most importantly by the buffering from carbonate-rich sediments. This buffering timescale is slow, such that there can in fact be a decoupling of ocean pH from the main buffering capacity of seawater (see Honisch et al, Science, 2012 The Geological Record of Ocean Acidification). This statement also fails to acknowledge the thermodynamic threshold to skeleton-building (saturation state), which for corals and many other organisms falls well above pH 7. “If they had called it something else, such as ‘lower alkalinity’, it wouldn’t have been as catchy”Adam Subhas PhD candidate, Caltech: CO2 has zero effect on alkalinity. “They” would have never called Ocean Acidification ‘lower alkalinity’, because that is simply an incorrect thing to say. 2. The article misrepresents the nature of scientific inquiry “The review found that many studies had used flawed methods, subjecting marine creatures to sudden increases in carbon dioxide that would never be experienced in real life. In some cases it was levels far beyond what would ever be reached even if we burnt every molecule of carbon on the planet”Ken Caldeira Senior Scientist, Carnegie Institution for Science: It is normal in scientific investigation to study impacts of large doses as a step towards understanding impacts of smaller doses. Just because a study considered high doses, that in no way undermines the value of a study. Jean-Pierre Gattuso Research Professor, CNRS, Université Pierre et Marie Curie and IDDRI: This is an incorrect statement which has already been debunked before, including by two of the authors of the paper this manuscript referee to. Hurd C. L., Cornwall C. E., Dupont S., Gattuso J.-P., Hoegh-Guldberg O., Gao K. & Lagos N. A., 2015. Ocean acidification: Laboratory seawater studies are justified. Nature 525:187. Extreme values are useful for physiologists to elucidate the cellular and molecular pathways confering susceptibility or resistance to elevated CO2. Yang et al. (2016; fig. 8d) showed that most of the data on the biological response to ocean acidification archived in a World Data Centre were collected at pCO2 values below 1000 uatm, in agreement with the business-as-usual CO2 emission scenario. Yang Y.et al., 2016. Data compilation on the biological response to ocean acidification: an update. Earth System Science Data 8:79-87. “An “inherent bias” in scientific journals in favour of more calamitous predictions has excluded research showing that marine creatures are not damaged by ocean acidification, which is caused by the sea absorbing carbon dioxide from the atmosphere.”Jean-Pierre Gattuso Research Professor, CNRS, Université Pierre et Marie Curie and IDDRI: A publication bias towards positive results is inherent to all fields of research. But I believe that it is far from being as bad as the article suggests. The most recent and comprehensive meta-analysis of the impact of ocean acidification shows that many processes and taxonomic groups exhibit no statistically significant response (Kroeker et al., 2013). This demonstrates that many non-calamitous papers are published. Kroeker K. et al., 2013. Impacts of ocean acidification on marine organisms: quantifying sensitivities and interaction with warming. Global Change Biology 19:1884-1896. Ken Caldeira Senior Scientist, Carnegie Institution for Science: In all fields of research, it is much easier to publish a paper saying ‘We were able to develop convincing evidence that X affects Y’ than to publish a paper saying that ‘We were not able to develop convincing evidence that X affects Y’. That is a bias that is inherent in all of modern science and is not specific to ocean acidification research. Mark Eakin Scientist, Coordinator of NOAA’s Coral Reef Watch, National Oceanic and Atmospheric Administration: This is an inflammatory twisting of the author’s words. Browman discusses the well-known bias against publication of negative results. It has nothing to do with the direction of the signal, only the inability of the researchers to demonstrate an effect in their experiments. It has nothing to do with how “calamitous” the predictions are. In fact, sometimes the negative results would have been more calamitous depending on the experimental design. “Dr Browman, a marine scientist for 35 years, said he was not saying that ocean acidification posed no threat, but that he believed that “a higher level of academic scepticism” should be applied to the topic.Ken Caldeira Senior Scientist, Carnegie Institution for Science: By making such broad statements, Dr Browman is undermining the hard work of many people who have spent a huge amount of effort to document the effects of ocean acidification on many marine species. If Dr Browman wants to attack particular studies, he should cite particular statements from particular papers that he thinks are false. It is inappropriate to make vague accusations denigrating an entire field of inquiry. Adam Subhas PhD candidate, Caltech: There is a degree to which scientific skepticism should be applied to Ocean Acidification experiments. There are many “cook and look” type experiments that investigate short term, single-species effects which are often not representative of the real world, include no mechanistic or physiological explanation, and lack any sort of adaptive response from the organism itself. However, the field as a whole is moving away from this approach, thanks to the hard work of many ecologists, biologists, chemists, and oceanographers working together, generating data, and participating in the scientific method. Examples of this progress can be found in the articles Gattuso, Caldeira, and I, have cited above."
https://science.feedback.org/review/sea-level-rise-global-warming-climate-change/,1.7,"The New York Times, by Justin Gillis, on 2016-02-22.",,"""Seas Are Rising at Fastest Rate in Last 28 Centuries""",,,,,"Justin Gillis reports on new results showing that the current rate of sea level rise is unprecedented in a record dating back 2,000 years. The article explains that this rise is attributable to human-induced climate change, and that higher sea levels are already impacting coastal communities. The seven scientists who reviewed the article confirmed that it is accurate and insightful. Note that results about the increased frequency of coastal flooding in the US discussed in this article are from a Climate Central’s analysis that has not undergone formal peer-review. We wish to stress this point as peer-review is a mechanism that allows to increase the trust one can have in a result and ensures the work meets higher standards of scientific quality.See all the scientists’ annotations in context GUEST COMMENTS: Robert Nicholls Professor of Coastal Engineering, University of Southampton:The article by Kopp et al (on which The New York Times is reporting) provides a quite convincing attribution of much of 20th century and early 21st century sea-level rise to human-induced warming. It shows that the recent rate of rise in sea level is unprecedented in more than 2000 years of record and that these changes are almost certain to accelerate substantially into the future. Interestingly this new analysis also appears to reinforce the conclusions of the IPCC Fifth Assessment Report about sea-level rise expectations through the 21st century. While human activity has been linked to sea level rise forecasts before, here human activity is linked to observed changes, which is an important improvement. REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Andrea Dutton Visiting Associate Professor, University of Wisconsin:This article is an accurate and insightful summary of the recently published research on this topic. Justin Gillis has a strong background in this topic which comes across through his careful language and nuanced understanding of the issues. Note however that the Climate Central report is not peer-reviewed literature. This was not clear in much of the press coverage and was not clear at the beginning of this article where these two “studies” are presented as equals. Even if the report by Climate Central is correct, it should not be elevated to the status of peer-reviewed literature by the media. James E Neumann Principal, Industrial Economics:The article is highly accurate and cites relevant new work, but omits other recent relevant work (Andrea Dutton has provided in annotations) and what might be helpful discussions of the key mechanisms of sea level rise. These are relatively minor points. Aimée Slangen Researcher, Royal Netherlands Institute for Sea Research (NIOZ):The article gives a good overview and insight into the main conclusions of both the Climate Central report (by Dr. Strauss) and the research paper (by Dr. Kopp), and links the two well. Rasmus Benestad Senior scientist, The Norwegian Meteorological institute:The article gives a good account of some new papers that recently have been published about the global sea level. Stephan Lewandowsky Professor, University of Bristol:The article does a very good job reporting the papers and is entirely accurate. I did not spot any errors or even minor glitches–well done. Mr Gillis does an exemplary job in reporting science factually and accurately. Notes: [1]See the rating guidelines used for article evaluations. [2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The quotes below are from Justin Gillis’ article. 1. Current pace of sea level rise is unprecedented in history of human civilization and this rate of sea level increase cannot be explained without human influence. “in the absence of human emissions, the ocean surface would be rising less rapidly and might even be falling.” Aimée Slangen Researcher, Royal Netherlands Institute for Sea Research (NIOZ):To clarify: the study by Kopp et al uses hypothetical temperature scenarios to show that if temperatures in the 20th century had been similar to the average temperature of the years 500-1800, sea-level rise would have been less rapid or even falling. “Based on extensive geological evidence, scientists already knew that the sea level rose drastically at the end of the last ice age… They also knew that the sea level had basically stabilized, like the rest of the climate, over the past several thousand years”Emmanuel M Vincent Research Scientist, University of California, Merced:This statement is supported by a recent report in Nature Climate Change written by 22 scientists. The figure below shows that global sea level rose by about 100 meters at the end of the last ice age 15 thousand years ago and that sea level had stabilized more than 5 thousand years ago. This helps clear a common misconception that current rate of sea level rise could be simply due to the end of the ice age. Long-term global mean sea-level change for the past 20,000 years (black line) based on palaeo sea level records and projections for the next 10,000 years for four emission scenarios. From Fig. 2 in Past and future changes in global mean sea level 2. Sea level rise has and will have very significant economic impacts, for instance by flooding coastal cities. “The worsening of tidal flooding in American coastal communities is largely a consequence of greenhouse gases from human activity, and the problem will grow far worse in coming decades, scientists reported Monday.” Andrea Dutton Visiting Associate Professor, University of Wisconsin:An accurate summary of the research that was published by Kopp et al. in PNAS. In fact, if anything, it is somewhat of an understatement given that the worsening of tidal flooding may be ENTIRELY due to the influence of greenhouse gases from human activity. This is based on the statement in the published research by Kopp et al (PNAS) that sea level in the 20th century may have “very likely risen by between -3 cm and +7 cm “, which is a way of saying that it may have fallen by 3 cm or risen by up to 7 cm over that time frame in the absence of [human-induced] global warming. Robert Nicholls Professor of Coastal Engineering, University of Southampton:While the rises in sea levels to date are small, they have had impacts and greatly increased nuisance flooding along the US East Coast as Strauss et al demonstrate. As sea levels continue to rise this will be extremely challenging to residents of the US East Coast and globally around the world’s coasts. This shows the benefits of sustained reductions in greenhouse emissions. Further these coastal communities will need to adapt in a systematic way to the sea-level rise that has occurred which is also challenging. “roughly three-quarters of the tidal flood days now occurring in towns along the East Coast would not be happening in the absence of the rise in the sea level caused by human emissions.” Emmanuel M Vincent Research Scientist, University of California, Merced:The trend in the number of “coastal flood days” in the US is convincing supporting evidence of this conclusion. Visualization created by Climate Central “Experts say the situation would then grow far worse in the 22nd century and beyond, likely requiring the abandonment of many coastal cities.” Andrea Dutton Visiting Associate Professor, University of Wisconsin:This statement is accurate. See Clark et al. (2016) Nature Climate Change (Consequences of twenty-first-century policy for multi-millennial climate and sea-level change, currently available online) or Dutton et al. (2015) Science, Sea-level rise due to polar ice-sheet mass loss during past warm periods. 3. Sea levels are expected to rise 0.5 to 1 meter on average by 2100, and the rise should impact mean sea levels for millenias. “One of the authors of the new paper, Dr. Rahmstorf, had previously published estimates suggesting the sea could rise as much as five or six feet by 2100.” Andrea Dutton Visiting Associate Professor, University of Wisconsin:This is an accurate representation of the previous and current research. It might have been nice to also note here that because the models he used probably don’t fully account for the rate of mass loss of ice from the polar ice sheets that the 3-4 feet estimate in the current research and in the IPCC may well underestimate the eventual magnitude of global mean sea-level rise by 2100. “In an interview, Dr. Rahmstorf said the rise would eventually reach five feet and far more — the only question was how long it would take. Scientists say the recent climate agreement negotiated in Paris is not remotely ambitious enough to forestall a significant melting of Greenland and Antarctica, though if fully implemented, it may slow the pace somewhat.” Andrea Dutton Visiting Associate Professor, University of Wisconsin:This is an accurate summary. To learn more about the eventual degree of melting in the future, see Clark et al (2016) Nature Climate Change (Consequences of twenty-first-century policy for multi-millennial climate and sea-level change, currently available online)."
https://science.feedback.org/review/patrick-michaels-the-climate-snow-job-the-wall-street-journal/,-1.8,"The Wall Street Journal, by Patrick Michaels, on 2016-01-24.",,"""The Climate Snow Job""",,,,,"The article misleads readers with a series of sweeping claims about distinct aspects of climate science and the implications of global warming for the global economy. Most of the article is devoted to casting doubt over the accuracy of the global temperature record. The author uses detailed technical descriptions to distract readers from the inaccuracies of the article, which involve cherry-picking data to support multiple unsubstantiated and discredited claims.See all the scientists’ annotations in contextGUEST COMMENTS: Peter deMenocal Professor, Lamont-Doherty Earth Observatory, Columbia University, and Director, Center for Climate and Life: This is a simple, deliberate, and misleading conflation of (natural) El Niño variability and (anthropogenic) global warming trend to suggest that 2015 warmth is soley related to El Niño variability. It is very easy to debunk Michael’s suggestion that 2015 warmth is due only to El Niño, as shown by the other reviewers. The weather-related reinsurance risk statement itself is plain false (just read the MunichRe corporate statements), as is the statement that “Without El Niño, temperatures in 2015 would have been typical of the post-1998 regime“.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Ken Mankoff Senior Scientist, Geological Survey of Denmark & Greenland: The author attributes the record 2015 temperature only to El Niño. El Niño contributed, but was assisted into the record books by a general warming trend that is directly linked to human CO2 emissions. Every data set has issues and is incomplete or incorrect in some sense, and can be used to question a result, but a proper analysis of multiple independent data shows what is really happening. The author did not do this, and instead cherry-picks data and misleads the reader. Jennifer Francis Senior Scientist, Woods Hole Research Center: Patrick Michaels (note he is referred to as a ‘climatologist’ even though he does not have a PhD in climate science) contorts and misrepresents facts, deliberately misleads with disinformation, and demonstrates either his lack of knowledge or willful ignorance of the science. Britta Voss Postdoctoral Research fellow, U.S. Geological Survey: The author cherry-picks data to support multiple unsubstantiated and discredited claims. The detailed technical descriptions distract from the overall inaccurate picture presented by the article. Emmanuel M Vincent Research Scientist, University of California, Merced: The article argues about the effect of El Niño on global temperature but fails to include relevant information about the long term trend in global temperature observed by multiple lines of evidence. Rasmus Benestad Senior scientist, The Norwegian Meteorological institute: This letter is based on a series of misguided notions and does not rely on up-to-date knowledge. Victor Venema Scientist, University of Bonn, Germany: At least this Wall Street Journal piece penned by Patrick J. Michaels was not derogatory. James Renwick Professor, Victoria University of Wellington: This article is indeed a snow job, as the title implies. The author has twisted the facts and distorted the science wildly. The author is well known for his wildly inaccurate climate “forecasts”, see e.g. Patrick Michaels: Cato’s Climate Expert Has History Of Getting It WrongNotes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Featured Annotations: Below is a list of statements made by Patrick Michaels in his article along with comments and replies made by scientists. “Surface temperatures are indeed increasing slightly: They’ve been going up, in fits and starts” Victor Venema Scientist, University of Bonn, Germany: There are also other reasons why the global mean temperature changes from one year to the next, such as volcanoes and El Niño. You see these changes on top of the long-term trend due to increases in greenhouse gases. “in fits and starts” It is strange that Michaels emphasises this, because that is exactly the main reason why his idea that there was a “hiatus” in man-made global warming due to greenhouse gasses is so terribly wrong. Does anyone see a “hiatus” in the graph below? You no longer need statistics to tell you that this meme was wrong. “Before carbon dioxide from economic activity could have warmed us up, temperatures rose three-quarters of a degree Fahrenheit between 1910 and World War II.” Victor Venema Scientist, University of Bonn, Germany: Also before 1950 there was warming due to greenhouse gasses. Part of this warming was compensated by increases air pollution that also comes from burning fossil fuels. However, CO2 builds up, while air polution has a short life time. In the end, CO2 dominates. Before 1950 there was also warming due to natural causes due to less volcanoes and a stronger Sun. After 1950 we can say that our best estimate is that all warming was man-made, but also before 1950 part of the warming was man-made. All forcings (physical causes that change the temperature) are shown in this graph from the latest IPCC report. James Renwick Professor, Victoria University of Wellington: These changes are all a mix of solar radiation increase (before 1940), increased air pollution from industrialization mid-century, and greenhouse gas increase. Plus a few volcanoes and some natural variability. Models can capture all this really well, provided that they include the effects of greenhouse gas increase – otherwise, forget it. So sure, natural variations are in the mix, but human-induced greenhouse warming is becoming more important all the time. Shaun Lovejoy Professor, McGill University: This statement is a mixture of exaggeration and cherry picking. First for the cherry picking. Figure 1 shows that the period 1910-1944 had the largest 34 year warming since 1880. Figure 2 (see below) – the same data but plotted against the CO2 forcing, a surrogate for all anthropogenic effects – shows that by 1944 there was already about 0.3C (0.5F) of anthropogenic warming (i.e. 1944 was not “too early”). This is clarified in Fig. 3 that shows the residual: the estimate of the natural variability accounted for about 0.46C of the rise. This seems a lot for natural variablity – except that it was cherry picked to be the largest natural increase since 1880. Fig. 4 shows that it is almost exactly of the magnitude predicted by a 130-140 year return period. In other words this event is exactly as expected by the theory of anthropogenic warming! Such events are predicted by the theory. See : Lovejoy, S. 2014: Return periods of global climate fluctuations and the pause, Geophys. Res. Lett. 41, 4704-4710, doi: 10.1002/2014GL060478. Fig. 2: “Until last June, most scientists acknowledged that warming reached a peak in the late 1990s” Ken Mankoff Senior Scientist, Geological Survey of Denmark & Greenland: I’m not aware of any scientists that acknowledged this. This statement was always only true if you cherry-pick data and look at short time periods. 1998 was a record hot year, which is why many non-climate-scientists claimed “global warming stopped in 1998”, but that was incorrect. It was incorrect in 1999, and anytime between then and last June. See, for example, Climate myths: Global warming stopped in 1998 “a marginally significant warming trend in the data over the past several years, erasing the temperature plateau that vexed climate alarmists have found difficult to explain.” Britta Voss Postdoctoral Research fellow, U.S. Geological Survey: As this figure shows, the corrections made to the NOAA dataset last year only changed their global temperature estimates very slightly compared to their previous dataset. (See Karl et al., 2015, Science, for details). Regarding the “erasing” of the “temperature plateau” (aka “hiatus”), as NASA’s Gavin Schmidt pointed out, “The fact that such small changes to the analysis make the difference between a hiatus or not merely underlines how fragile a concept it was in the first place.” “When the Pacific circulation returns to its more customary mode, all that suppressed cold water will surge to the surface with a vengeance, and global temperatures will drop. Temperatures in 1999 were nearly three-tenths of a degree lower than in 1998, and a similar change should occur this time around, though it might not fit so neatly into a calendar year. Often the compensatory cooling, known as La Niña, is larger than the El Niño warming.” James Renwick Professor, Victoria University of Wellington: This avoids the point. If one fits a trend through just the El Niño years, or just the La Nina years, or just the neutral years, the result is the same – significant warming. ENSO adds year-to-year variations, but greenhouse gas increase provides the trend. source: National Climate Assessment 2014 “the rate of warming in the satellite-sensed data is barely a third of what it was supposed to have been” Victor Venema Scientist, University of Bonn, Germany: One wonders where this number, “a third”, comes from. The global mean temperature trend of the tropospheric temperatures (estimated by satellite) is very similar to that of the surface temperature over the short period for which we have satellite data. It is expected that the tropospheric temperature would rise a bit faster than the surface temperature, but this is a small deviation. Far from the completely false claim of Michaels that the warming is only a third of what it should be. As in any case, this deviation could be due to the models, the measurements, their data processing or the comparison. One would need to understand the reasons for this small deviation before one can claim that the models would need to be a little less sensitive. “50% the modeled temperature forecasts for the rest of this century” Rasmus Benestad Senior scientist, The Norwegian Meteorological institute: This is pure hand waving without any substance to support it. The comparison between climate models and measurements suggest a good agreement “The notion that world-wide weather is becoming more extreme is just that: a notion, or a testable hypothesis. As data from the world’s biggest reinsurer, Munich Re and University of Colorado environmental-studies professor Roger Pielke Jr. have shown, weather-related losses haven’t increased at all over the past quarter-century. In fact, the trend, while not statistically significant, is downward.” Laurens Bouwer Senior risk advisor, Deltares: This statement is not accurate, as 1) The main point is that up to now, we do not see an increase in loss records such as from Munich Re, due to anthropogenic climate change. That is not to say there is no increase in extreme weather, because there is. See IPCC SREX and AR5 reports, to which I also contributed. There is no signal in most loss records from floods and storms, though. So Patrick Michaels is misusing scientific information and consensus. And 2) it misses a point: there is an upward trend in losses, only after correction for population growth and wealth increase, this trend disappears. See the paper Roger Pielke and Munich Re wrote together, with me: Confronting Disaster Losses And also this recent review I did (freely accessible): Have Disaster Losses Increased Due to Anthropogenic Climate Change? James Renwick Professor, Victoria University of Wellington: Right… that’ll be why the Munich-Re website states (quoting Professor Peter Höppe, Head of Munich Re’s Geo Risks Research/Corporate Climate Centre): “Climate change is one of the greatest risks facing humankind this century. Through a part of its core business, the insurance industry is directly affected and therefore assumes a leading role in devising solutions for climate protection and adaptation to the inevitable changes.” “Last year showed the second-smallest weather-related loss of Global World Productivity, or GWP, in the entire record” Peter deMenocal Professor, Lamont-Doherty Earth Observatory, Columbia University, and Director, Center for Climate and Life: It is actually false, interesting that he brought this up. I consulted my reinsurance contacts and have several links that indicate the opposite view, that they are very concerned about mounting climate-related losses. Renaissance Re 2015 SEC document: “We believe, and believe the consensus view of current scientific studies substantiates, that changes in climate conditions, primarily global temperatures and expected sea levels are likely to increase the severity, and possibly the frequency, of weather related natural disasters and catastrophes relative to the historical experience over the past 100 years. Coupled with currently projected demographic trends in catastrophe-exposed regions, we currently estimate that this expected increase in severe weather, such as tropical cyclone intensity, over coming periods will increase the average economic value of expected losses, increase the number of people exposed per year to natural disasters and in general exacerbate disaster risk, including risks to infrastructure, global supply chains and agricultural production.” See also: “No climate-change deniers to be found in the reinsurance business“: “In Munich Re’s offices, there wasn’t much debate as the claims cheques flew out the door: The higher frequency of extreme weather events is influenced by climate change; and recent climate change is largely due to burning hydrocarbons. “I’m quite convinced that most climate change is caused by human activity,” says Peter Höppe, head of geo-risks research at Munich Re.“ Severe weather in North America, Munich RE"
https://science.feedback.org/review/james-taylor-2015-was-not-even-close-to-hottest-year-on-record/,-1.8,"Forbes, by James Taylor, on 2016-01-14.",,"""2015 Was Not Even Close To Hottest Year On Record""",,,,,"This is an inaccurate and misleading report. It only comments on the temperature in the troposphere (not at the surface of the Earth, where people live) and ignores most of the data available to discuss whether or not Earth’s climate is warming. It is based on a single, unpublished and contested record. Note that another contributor to Forbes published an accurate article on the subject, however the inaccurate article has been read 15-20 times more (26k) than the accurate one (1.5k) as of Jan 22, 2016.See all the scientists’ annotations in contextGUEST COMMENTS: Carl Mears Senior Research Scientist, Remote Sensing Systems (RSS): The author is guilty of ignoring the surface temperature record, which is probably more accurate than the satellite temperature record. The author ignores the fact that record temperatures often occur in the year following an El Nino, because the global temperature response tends to lag the El Nino SST anomaly by 3-4 months. The author engages in excessive derogatory name calling, and appears to lump scientists in with “global warming activists”. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: This article makes startlingly inaccurate claims about the earth’s surface and satellite temperature records, as well as attempts to ascertain the earth’s temperatures over the past two millennia through proxy measurements. The author would do well to talk to scientists involved in surface and satellite records and to consult the peer-reviewered scientific literature rather than blogs when writing in the future.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Alexis Berg Research Associate, Harvard University: Very misleading and biased article. The author tries to confuse readers by using the satellite record of the lower atmosphere temperature to disprove the fact that 2015 was the warmest year, when everybody else is in fact referring to the mean temperature at the surface. They are slightly different things. Satellite measurements do not disprove surface measurements. A more interesting question would be to understand the difference between the two. A better-informed – and less biased – author would have addressed that and tried to explain it to their readers. Julien Emile-Geay Assistant Professor, University of Southern California: This is a highly misleading piece by an author with a history of cherry picking. Nothing in this piece is factually accurate. Furthermore, in relying on discredited reports by the Heartland Institute instead of the peer-reviewed literature, the author completely misinterprets the paleoclimate record, which only strengthens the point that 2015 is an exceptionally warm year, not just since 1979 but for the past 10,000 years. David Easterling Chief of the Scientific Services Division, NOAA's National Climatic Data Center: The coverage is a bit disingenuous since it only uses one satellite data set, and emphasizes the troposphere rather than the boundary layer [surface] where people actually live. The surface and upper air are two very different areas and their temperatures differ for lots of scientifically valid reasons. James Renwick Professor, Victoria University of Wellington: This piece is a rehash of several points that have been refuted many times over. The “satellite temperature record” from Roy Spencer is trumpeted so much because it is the only record that shows slow warming. Victor Venema Scientist, University of Bonn, Germany: The Forbes post of James Taylor provides the deepest possible contrast to the accurate New York Times article on the 2015 temperature record. Eric Guilyardi CNRS Research Director, Université Pierre et Marie Curie & Professor, University of Reading: A biased piece that confuses scientists and activists, full of inaccuracies and even plain errors. The author has obviously no expertise in climate science and did not seek to get some to write his piece. Quite poor journalism, if the term even applies. Britta Voss Postdoctoral Research fellow, U.S. Geological Survey: The author uses inaccurate and misleading claims (based on evidence from scientifically discredited sources) and rhetorical devices to confuse the facts and bias readers against legitimate climate science. Nothing in this article is either scientific or novel. Those are stale talking points that are constantly recycled by political operatives in pursuit of an agenda. The article contains major scientific inaccuracies by claiming that most of the last 10,000 years and most of the past several thousand years were warmer than today (not true, see Marcott et al. 2013 or PAGES 2K). It omits the surface temperature data from the last 100 years, which show that it was a record warm year. It presents logical flaws by first showing the satellite data of lower tropospheric temperature estimates from 1979 to the present to say that 1998 was warmer than 2015 and then argues that the surface temperature record from the last 100 years was too short to make an argument. What I find most disturbing is that the author paints scientific facts as coming from “activists” and being “doctored”. Clearly an attempt to discredit science. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : Below is a list of statements made by James Taylor in his article along with comments and replies made by scientists.1. The hottest year on record, in terms of annual global average surface temperature, is 2015. “Forget what global warming activists would lead you to believe—2015 was not even close to the hottest year on record.” Britta Voss Postdoctoral Research fellow, U.S. Geological Survey: This is simply false. 2015 was indeed the hottest year on record. This was rigorously determined by a large group of climate scientists. By calling these scientists “global warming activists,” the author misleadingly implies that the claim is made by a fringe group of non-expert partisans. “So how do global warming activists get away with raising constant alarm and making such outrageous claims as 2015 being the hottest ever? The answer is misleading head-fakes, doctored temperature records, and a compliant media that is more than willing to push the agenda of global warming activists.” James Renwick Professor, Victoria University of Wellington: A wild misrepresentation of reality. Reputable scientists, not activists, compile these records. As for a compliant media, it’s generally the opposite. Many media outlets seem only too pleased to run disinformation pieces like this one, in the name of “balance”. “doctored temperature records” Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: The irony is that the “undoctored” raw temperature records also show that 2015 was the warmest year ever, and actually show a lot more global warming over the past 150 years: 2. Other climatic datasets are consistent with surface temperature data. “Satellite temperature readings going back to 1979 show 1998 was by far the warmest year in the satellite era” James Renwick Professor, Victoria University of Wellington: In that particular record, yes. But what does it measure? An estimate of temperature in a layer above the earth’s surface, derived from observations of radiation into space. It is one of the most adjusted and manipulated records out there. And it is about the only one that shows 1998 as the warmest year. Look at thermometer records, ocean temperature, ice melt, atmospheric moisture content, you name it. They all show the same things, that the earth system is warming steadily. Alexis Berg Research Associate, Harvard University: One wonders here if the author is aware that satellite measurements of the “Lower Atmosphere” (a few km in the atmosphere) do not measure the same thing as surface temperature. So they don’t need to be exactly the same. So in a sense he is comparing apples with oranges here (or mandarines with oranges, if you will). Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: Satellite records do not measure the surface of the earth, where we live; rather, they measure the temperature of the lower atmosphere. They are also subject to large uncertainties due to the need for corrections of factors like orbital decay and coverage / scan time changes. If you look at the uncertainty range of estimates for satellites, it is much larger than that of surface temperatures and really can’t tell us anything about the correctness of the surface temperature trend. “Satellite temperature measurements show 1998 and 2010 were warmer than 2015. Image courtesy of drroyspencer.com.” Victor Venema Scientist, University of Bonn, Germany: The UAH6.0 dataset has not been published yet and scientists have thus not had the opportunity to check these results. UAH6 used very different methods to estimate the temperatures and having a much smaller recent trend than the previous UAH5 dataset. An awkward choice to use UAH6.0 to contrast to the well vetted and more reliable trend estimates of the surface temperature by six different groups world wide. A balanced journalist would at least also show these results. “But we do have other reliable indicators of temperatures before the late 1800s, and the evidence shows temperatures have been warmer than today for most of the past several thousand years, including warmer-than-present temperatures for most of the human civilization time period” James Renwick Professor, Victoria University of Wellington: This is a complete fabrication. The paleoclimate record suggests that the current warmth is unprecedented for at least the last 1400 years. And it is the cause of the current warming (fossil fuel burning) that’s the real story. “we do have other reliable indicators of temperatures before the late 1800s” Julien Emile-Geay Assistant Professor, University of Southern California: How convenient that indicators of temperature are deemed “reliable” to support this fallacy, but unreliable otherwise! The author cannot have it both ways: if the temperature record is reliable prior to the instrumental era (starting in the 1800s), then it is a fortiori reliable afterwards ; and all surface temperature analyses show an extremely strong warming that cannot be explained without man-made forcing, CO2 leading the pack. The paleoclimate record unequivocally shows that temperature maxima coincide with high concentrations of greenhouse gases in the atmosphere (https://www.ipcc.ch/report/ar5/wg1/ Chap 5), which is also the cause of the present warming. 3. El Niño warmth in the eastern equatorial Pacific Ocean contributed to the record warmth, but more importantly, it occurred on top of the long-term global warming trend. “With a record El Niño, we should have experienced record high temperatures. Yet we didn’t.” Eric Guilyardi CNRS Research Director, Université Pierre et Marie Curie & Professor, University of Reading: We certainly did experience a record high temperature (as shown by James Renwick above. A 1 degree celsius (or 2 F) El Niño warming increases the global temperature by 0.1 deg C (or 0.2 F). This year’s El Niño has added about 0.3 deg C driving the global temperature up to 1 C (2 F) above the pre-industrial value. As decades go by the El Niño warming becomes relatively smaller and smaller compared to human induced global warming (+50% in the 90s and just +30% now for the same extreme El Niño). Victor Venema Scientist, University of Bonn, Germany: The last record of the satellite tropospheric temperatures in 1998 was in the year after an El Nino. This may well be the case again. Climate predictions on the short-term are difficult, but it is expected that 2016 will again be a record year. Carl Mears Senior Research Scientist, Remote Sensing Systems (RSS): Calendar years with record temperatures tend to occur in the year following the peak of the El Nino event. This was true for the 1997-1998 and 2009-2010 El Ninos in the satellite data. The fact that 2015 was a record year in the surface temperature record probably means that 2016 will even be a bigger record breaker. “Indeed, if a record strong El Niño cannot bring global temperatures back to the warmth of 1998, what can—and when will that be?” Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: In the surface temperature record, 5 independent groups all find that 2015 far exceeded the temperature of 1998 and was the warmest year on record by a significant margin:"
https://science.feedback.org/review/analysis-justin-gillis-2015-hottest-year-global-warming/,1.9,"The New York Times, by Justin Gillis, on 2016-01-20.",,"""2015 Was Hottest Year in Historical Record, Scientists Say""",,,,,"The article accurately covers the news that the global surface temperature of the planet in 2015 has set a new record, well above any previous measurement. It correctly explains that this new record is due to the combined effects of a strong El Niño event (currently at its peak intensity) in the Pacific, and the continued global warming effect of human emissions of greenhouse gases.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. James Renwick Professor, Victoria University of Wellington: A very nice, well-written, and factual article, including comment from some of the globe’s leading climate scientists. Pretty much everything in this article is correct and based on peer-reviewed literature. Eric Guilyardi CNRS Research Director, Université Pierre et Marie Curie & Professor, University of Reading: A well documented article with properly quoted top experts. The many facts to consider on this topic are mostly there. Julien Emile-Geay Assistant Professor, University of Southern California: Very balanced article looking at multiple sources of information and interviewing qualified climate scientists. Victor Venema Scientist, University of Bonn, Germany: A joy to read a US newspaper article that accurately reports on the changes in the global temperatures. Rasmus Benestad Senior scientist, The Norwegian Meteorological institute: The article accurately reflects the scientific findings that 2015 is the hottest year on record. Emmanuel M Vincent Research Scientist, University of California, Merced: An accurate and well documented report on the finding that 2015 is the hottest year on instrumental record by a wide margin. Andreas Schmittner Associate Professor, Oregon State University: This article is an excellent example of conveying scientific findings.Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Featured Annotations: Below is a list of a few statements made by Justin Gillis in his article along with comments and replies made by scientists. “When temperatures are averaged at a global scale, the differences between years are usually measured in fractions of a degree” James Renwick Professor, Victoria University of Wellington: Important to understand this. Global/annual average temperatures change by only a tiny fraction from year to year, usually. The jump from 2014 to 2015 is really remarkable. “The strong El Niño has continued into 2016, raising the possibility that this year will, yet again, set a global temperature record” Eric Guilyardi CNRS Research Director, Université Pierre et Marie Curie & Professor, University of Reading: Yes, it is likely that 2016 will also be a near record year for global surface temperature. It is also possible that 2017 will see a La Niña occur (usually following a large El Niño) and that this year will be cooler than 2015 and 2016. This is why detecting climate change and a human influence cannot be done on just a few specific years. Climate scientists consider several decades to average out the naturally variability of the climate. A few very cold days in spring do not imply winter has arrived, do they?"
https://science.feedback.org/review/analysis-of-chris-mooney-scientists-say-human-greenhouse-gas-emissions-have-canceled-the-next-ice-age/,1.7,"The Washington Post, by Chris Mooney, on 2016-01-13.",,"""Scientists say human greenhouse gas emissions have canceled the next ice age""",,,,,"The article presents an accurate account of recently published research which suggests that human-induced global warming will delay the onset of the next ice age by 50,000 years. The research supports the findings of several studies published over the past 15 years, and is consistent with the scientific consensus that human activity is changing the climate with very long-term consequences. Although anthropogenic greenhouse-gas emissions will likely delay the onset of the next ice-age, this is no cause for complacency. As the research notes, at pre-industrial levels of CO2 the planet would not descend into an ice age for another 50,000 years. By contrast, the adverse consequences of global warming are expected to intervene in the coming years, decades and centuries.See all the scientists’ annotations in contextGUEST COMMENTS: Lee Kump Professor, PennState University: That atmospheric carbon dioxide buildup from fossil fuel burning likely will delay the onset of the next glaciation is actually old news; the last emergence of the idea I’m aware of was in 2008, in an article reporting on the work of University of Chicago geoscientist David Archer. The new idea that emerges from the recently published work of Ganopolski et al. is that even if preindustrial levels of 280 ppmv atmospheric CO2 had been sustained to the present and beyond, Earth would have enjoyed an anomalously prolonged warm, interglacial state compared to past interglacials. This finding appears to be robust, but should be evaluated using other earth system models appropriate to study the complicated process of glacial inception. Ken Caldeira Senior Scientist, Carnegie Institution for Science: One thing to be aware of is that this conclusion is not new. For instance, Uchikawa and Zeebe (2008), using a model based on that of Walker and Kasting (1992) came up with the same conclusion, as well as Archer and Ganopolski (2005) who concluded: “We predict that a carbon release from fossil fuels or methane hydrate deposits of 5000 Gton of Carbon could prevent glaciation for the next 500,000 years”. That is not to belittle the present article, who has performed more sophisticated ice sheet modeling than in previous studies. Thus, I would see the new study as giving us greater confidence in conclusions reached by Ganapolski and others in earlier publications.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. The IPCC’s latest projections for sea level rise by century’s end (e.g. IPCC summary for policymakers) range from 40 cm to 63 cm (or 15″ to 25″). A notable component of that will be due to ice loss. So while our carbon emissions may have initially delayed an ice age, this benefit has been traded for the likelihood of fairly adverse consequences in the future. James Renwick Professor, Victoria University of Wellington: The article is essentially a factual account of the content of the paper, and the material (in the paper and in the WaPo article) covers ideas that have been current for several years, that human-induced greenhouse gases increase has delayed the next ice age. Guillaume Leduc Researcher, CEREGE: The article fairly reports on one of the findings of one article that has recently been published in the scientific journal Nature. On multi-millenia timescales, orbital parameters are considered as pacemakers of ice ages, but now that CO2 has massively been injected in the atmosphere the next ice age which should have already been much into the pipeline is already aborted. The article indeed talks about many things clearly established for decades, but that are still valid. Rasmus Benestad Senior scientist, The Norwegian Meteorological institute: The reporting of the research is objective, although the research itself may be perceived as a bit speculative at this point, even if its plausible. The results are interesting, and need to be confirmed through further work. Alexis Berg Research Associate, Harvard University: This is a nice article which reports on a recent Nature study accurately. However, for the sake of clarity and to avoid potential misinterpretations of such results, the implication that human greenhouse gas emissions have “canceled the next ice age” (in 50,000 years) could have been compared with the implications for near-term global warming. Article continues the tradition of excellence in climate and energy reporting by Chris Mooney and others at the Washington Post. Clearly explains state of the science, though I would have liked to see other anthropogenically and naturally influenced climate forcers (especially aerosols and methane) brought into the discussion.Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time."
https://science.feedback.org/review/analysis-of-matt-ridley-benny-peiser-your-complete-guide-to-the-climate-debate/,-1.5,"The Wall Street Journal, by Matt Ridley, Benny Peiser, on 2015-11-27.",,"""Your Complete Guide to the Climate Debate""",,,,,"The opinion piece in the WSJ by Matt Ridley & Benny Peiser contains numerous false statements, cherry-picked evidence, and misleading assertions about climate science. It attempts to surround the hard facts about climate change with clouds of uncertainty, even though these facts are agreed to by the scientific academies of every major country in the world and the vast majority of the world’s climate scientists. Facts and/or studies are cherry picked or placed out of context to support the main claim that global warming is not as bad as we feared. For example the assertion that 1.5C of warming would be “beneficial” is one that very few scientists or economists agree with, and is contradicted by the overwhelming weight of evidence in the IPCC’s reports showing that the adverse impacts from climate change will far outweigh the benefits from carbon-dioxide induced greening and other heat-related effects. See below for a list of scientists’ comments on the article’s statements.See all the scientists’ annotations in context GUEST COMMENTS: Steven Sherwood Professor, University of New South Wales: This article peddles the usual false statements masquerading as opinion that we have been seeing for years, and would not be published by a reputable publisher. Most of the scientific statements in the article are false or misleading. Mark Jacobson Professor of Civil and Environmental Engineering, Stanford University: Misleading article with cherry-picked information placed out of context. Eric Wolff Professor, University of Cambridge: The article starts with an obvious logical fallacy: that because people attend a long-planned meeting on climate change, they must think this issue is more important than terrorism. REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Alexis Berg Research Associate, Harvard University: The authors cherry-picks facts and/or studies to try to make the claim that, essentially, global warming is not as bad as we feared. It is a very biased and misleading presentation of the science. Twila Moon Research Scientist, University of Colorado, Boulder: This article is full of convenient cherry-picking and misleading statements. The level of information provided suggests the author is aware of the actual scientific findings that clearly demonstrate the severity of the climate change, but is building false conclusions by cherry picking or making false or unspecific statements. Emmanuel M Vincent Research Scientist, University of California, Merced: The authors omit to mention all the evidence that go against his narrative, this is cherry picking. For instance, the claim that extreme events are not increasing as a response to the ongoing warming of the climate can only be made by not considering the fact that we clearly observe an increase in the severity of both heat waves and heavy rainfall events for instance. William Anderegg Associate Professor, University of Utah: The article contains rampant cherry-picking, misleading statements, and flawed logic. Its presentation of the science is highly biased and inaccurate. Rasmus Benestad Senior scientist, The Norwegian Meteorological institute: The article makes a number of false claims, such as the planet has been warmer during the last 10000 years. The claim that there has been no increase in frequency/intensity of storms/floods/droughts is misleading. There has been increases in extreme precipitation. It’s wrong that the climate sensitivity is “likely to be anything from 1.5 to 4.5 degrees Celsius” – the most likely value is in the central parts of this range, and the fringe values are less probable. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Featured Annotations: Below is a list of statements made by Matt Ridley and Benny Peiser in their Wall Street Journal article along with comments and replies made by scientists. “What precisely makes these world leaders so convinced that climate change is a more urgent and massive threat than the incessant rampages of Islamist violence?” Julien Emile-Geay Assistant Professor, University of Southern California: Studies like this one: Climate change in the Fertile Crescent and implications of the recent Syrian drought. It is one of many examples illustrating how climate stressors may bring societies into conflict over scarce resources. The exact number of future climate victims is impossible to compute, but even by the most conservative estimates it is many orders of magnitude greater than the hundreds (or conservatively thousands) of people killed yearly by terrorist acts. Eric Wolff Professor, University of Cambridge: The article starts with an obvious logical fallacy: that because people attend a long-planned meeting on climate change, they must think this issue is more important than terrorism. Alexis Berg Research Associate, Harvard University: False dichotomy. Climate change and terrorism both can and should be addressed – no matter how one ranks them. By the author’s logic, there couldn’t be a summit on anything else than terrorism right now. Mark Jacobson Professor of Civil and Environmental Engineering, Stanford University: I think the authors are ignorant of the fact that combustion of fossil fuels and solid biofuels today kills between 4-7 million people worldwide EACH year due to the air pollution impacts alone, and these deaths are preventable. This is referenced here. Anthony Barnosky Professor, University of California, Berkeley: Climate change has now been shown to be a contributing cause to the rise of the Islamic State in Syria and a chief national security concern. Happening now are the current refugee crisis and international terrorism spawned by ISIS—a legacy of how climate change helps precipitate conflict as a threat multiplier. Past examples include the Arab Spring uprising (major contributor was a failed crop in Egypt from intense drought), riots in Pakistan and attacks on government officials when drought meant choosing between water to drink and water for hydropower. See recent comments by National security adviser Susan Rice. “world temperatures, because they have gone up only very slowly, less than half as fast as the scientific consensus predicted in 1990” Steven Sherwood Professor, University of New South Wales: This statement is false. The IPCC predicted that warming between 2015 and 1990 would be within about 0.35 and 0.60C; the actual temperature in 2015 will be about 0.5C above the average of years around 1990, so a bit above the middle of the range originally predicted by the IPCC. “the world is barely half a degree Celsius (0.9 degrees Fahrenheit) warmer than it was about 35 years ago” Alexis Berg Research Associate, Harvard University: This kind of statement seems to imply that 0.5 C change in global temperature is negligible. For reference, readers unfamiliar with the order of magnitude of changes in global temperature should be reminded that the difference between today’s global temperature and that of the the Last Glacial maximum (around 20,000 years ago), when ice sheets extended over northern North America and Northern Europe/Asia, is estimated to be only around 4-5 C (e.g., Annan, J. D. and Hargreaves, J. C.: A new global reconstruction of temperature changes at the Last Glacial Maximum) A warming of a few degrees C globally, as projected today under a business-as-usual scenario, is thus something of geological magnitude. Anthony Barnosky Professor, University of California, Berkeley: Global temperature rise has of course been almost double what this article implies if you compare it to preindustrial rather than just the past 35 years. Which means warming has accelerated, not slowed, contrary to the presentation in this article. “Also, it is increasingly clear that the planet was significantly warmer than today several times during the past 10,000 years.” William Anderegg Associate Professor, University of Utah: In addition to likely wrong, this has absolutely no bearing on current human-caused warming. The projections of current warming will greatly exceed temperatures of the past 10,000 years and, more importantly for society and ecosystems, the rate of anthropogenic warming already greatly exceeds any temperature changes in the past 10,000 and even several million years. This rate of warming can have massive societal consequences and will be exceptionally hard for ecosystems and societies to adapt. Eric Wolff Professor, University of Cambridge: This is incorrect. It is notoriously hard to estimate a global average temperature, even today, let alone in the past. However the most comprehensive attempt to do so was by Marcott et al (A reconstruction of regional and global temperature for the past 11,300 years, Science) They found that early Holocene (10000 to 6000 years ago) warmth was followed by a slow cooling of about 0.7 degrees in the last 5000 years. The warming of the last century has taken global average temperature just above the maximum of the early Holocene – albeit so far only for a short period of time. However, it is clear that as warming continues we are entering a prolonged period that is significantly warmer than any period in the last 10000 years. “there has been no increase in frequency or intensity of storms, floods or droughts, while deaths attributed to such natural disasters have never been fewer” Steven Sherwood Professor, University of New South Wales: This statement is not justified as several studies are now reporting increases in severe rains and in storm damages even when non-environmental factors are accounted for. Moreover the authors ignore heat waves which show the clearest increase and kill more people than the ones they mention. Alexis Berg Research Associate, Harvard University: The authors seem to carefully select the types of climate extremes for which, despite projections of increased frequency/intensity of such extremes, observations over recent decades do not allow us to say if present trends are consistent with projections (e.g., droughts). Note that for other types of climate extremes, like temperature extremes, heat waves, or high-intensity rainfall, observations are in agreement with projections and show an increase attributable to human influence- e.g., Fischer and Knutti, 2015, Anthropogenic contribution to global occurrence of heavy-precipitation and high-temperature extremes, Nature Climate Change. “Antarctica is gaining land-based ice, according to a new study by NASA scientists published in the Journal of Glaciology” Twila Moon Research Scientist, University of Colorado, Boulder: This study examined Antarctic ice sheet mass changes until 2008 and presents a single study of Antarctic ice mass. Also, the mechanism indicated for mass change – increased snowfall – is actually a result of a warming atmosphere and an understood change that is consistent with scientific understanding. Perhaps more pertinent, however, is that other studies, including of more recent changes have suggested overall ice loss and, most important, large future ice loss. Recently published articles (Joughin et al. 2014, Rignot et al. 2014) looking at changes on coastal Antarctic ice shelves shows that we have likely already entered a period of major ice shelf retreat, with no mechanisms in sight to stop this retreat over the next 100s of years. The implication of ice shelf and glacier retreat around the Antarctic coast is increased ice loss over the next 10s to 1000s of years. There is a very large body of scientific work examining Antarctic ice sheet mass trends and there is community agreement that future ice loss is expected and will be worse if global temperatures increase more. Jonathan Bamber Professor, University of Bristol: West Antarctica has been losing mass at an increasing rate since the 1990s and, irrespective of what is happening further East, that trend looks set to continue. Going to the other end of the Earth, the Greenland ice sheet has also been losing mass at an accelerating rate since around 1995. Greenland is now the single biggest source of mass to the oceans. These trends at both poles are huge signals that are unequivocal and uncontested. “Sea level continues its centuries-long slow rise—about a foot a century—with no sign of recent acceleration.” Emmanuel M Vincent Research Scientist, University of California, Merced: “Recent” is not a precise term. On climate relevant scale, evidence shows that sea level rise has been accelerating. See for instance the figure below from Jevrejeva et al see also: Church (2008) Understanding global sea levels: past, present and future “But scientists disagree: They say there is great uncertainty” William Anderegg Associate Professor, University of Utah: This is highly misleading. Uncertainty is a fixture of life and is absolutely no reason for not taking policy action. There will always be uncertainty in science (in the form of standard deviations around estimates, for instance), but the scientists fundamentally do not disagree that: 1) humans’ emissions of greenhouse gases are the primary cause of climate change of the past 50-60 years, and 2) consequences are likely to be significantly harmful. See here and here. “It projects that temperatures are likely to be anything from 1.5 to 4.5 degrees Celsius (2.7 to 8.1 degrees Fahrenheit) warmer by the latter part of the century” Victor Venema Scientist, University of Bonn, Germany: This is the range for the Equilibrium Climate Sensitivity, not for the temperature in 2100. This temperature depends on how much we will mitigate climate change for which there are no predictions. This is a wide range of climate sensitivities, but not a sign of disagreement in the scientific community as the op-ed suggests. This range is a fair summary of the evidence for most scientists. Steven Sherwood Professor, University of New South Wales: The authors confuses the “sensitivity” (which they correctly notes ranges from 1.5-4.5C) with the actual warming that we’d have by 2100 (which ranges from 3-6C). There is no way that 3C of warming would be beneficial, and there is no way that we would get away with less than 3C of warming on a business-as-usual emissions pathway. 4C or more of warming would probably render some regions of the planet uninhabitable due to heat stress and cause massive disruption to all societies; 3C might even be enough to do that, we don’t know. “…that is, anything from mildly beneficial to significantly harmful.” Alexis Berg Research Associate, Harvard University: This sentence is very misleading. Even assuming that 1.5 C would be mildly beneficial – which is an unsubstantiated claim at this point – this sentence omits to mention that this more modest warming implies strong and rapid human action to limit greenhouse gas emissions – it is not at all an equally likely outcome of a business-as-usual scenario! A large part in the uncertainties from IPCC projections for the end of the 21st century is due to human behavior, e.g., mainly how much of fossil fuels we will burn (RCPs on the figure below). Note as well that for a business-as-usual scenario (RCP8.5), warming does not stop in 2100, but goes on after that. Steven Sherwood Professor, University of New South Wales: The assertion that 1.5C of warming would be “beneficial” is one that very few scientists or economists would agree with other than Richard Tol. It is true that CO2-induced greening will be beneficial, but how beneficial compared to the problems from greater heat and shifting rainfall patterns is dubious at best. “a new study by a leading climate economist, Richard Tol of the University of Sussex, concludes that warming may well bring gains, because carbon dioxide causes crops and wild ecosystems to grow greener and more drought-resistant.” Victor Venema Scientist, University of Bonn, Germany: It is a good idea to check the source. In this case the link goes to an unpublished manuscript. The manuscript only cites one study with positive impacts. The one of Dr. Tol himself for a 1°C temperature rise, which is a point we have just reached. That impacts for this study become statistically significant only at 3.5°C is because the economic uncertainties are so large. Uncertainties go both ways. William Anderegg Associate Professor, University of Utah: This is an old and largely debunked idea. The best available evidence suggests that while carbon dioxide concentrations do help some crops in some regions, the increases of temperature and drought stress are non-linear and have and will mostly overwhelm positive effects. In fact, climate change has probably driven declines in crop production of 2 of the 4 largest global crops even in the past 30 years. “A key study published in the Journal of Climate this year by Bjorn Stevens of the Max Planck Institute for Meteorology in Hamburg, Germany, found that the cooling impact of sulfate emissions has held back global warming less than thought till now” Victor Venema Scientist, University of Bonn, Germany: That clouds and aerosols are an important reason for the large confidence interval for the climate sensitivity is generally accepted. However, it is an exaggeration to claim that Bjorn Stevens found this. He presented limited evidence that makes a case for future research into this topic. More in general, one should never judge the state of the art based on single papers, especially new papers. “Scientific skeptics are now routinely censored, or threatened with prosecution.” Britta Voss Postdoctoral Research fellow, U.S. Geological Survey: This is misleading as it implies that climate skeptics are being threatened with prosecution because of their skeptical views. In reality, the questions of legality directed at climate skeptics (or, more significantly, fossil fuel companies) are based on concerns of conflict of interest, as scientists and others expressing views on climate science that are contradictory to mainstream consensus have in some cases been found to derive significant funding from fossil fuel companies and other groups that stand to profit from delaying climate policies. The recent example of Willie Soon, the Harvard-Smithsonian researcher who neglected to disclose his funding from fossil fuel companies when publishing research skeptical of established climate science, is a prime example of such a conflict of interest."
https://science.feedback.org/review/forbes-james-taylor-top-10-global-warming-lies-that-may-shock-you/,-2,"Forbes, by James Taylor, on 2015-02-09.",,“Top 10 Global Warming Lies That May Shock You”,,,,,"According to Forbes.com, this article has been read more than 110,000 times, making it one of Forbes’ most read article on climate in 2015, and author James Taylor is a popular contributor who writes about energy and environment. So how accurate was this article? Not accurate at all. According to scientists, this article contains numerous factual mistakes and flawed logic about basic science, and the reporting is based on uncredible sources. See the list below for more.See all the scientists’ annotations in context If the link does not work due to the high number of ads on Forbes, install Hypothesis bookmarklet or extension in your browser and switch it on from the article page. GUEST COMMENTS: Peter Reich, Regents Professor and Distinguished McKnight University Professor in Forest Resources, University of Minnesota This is an unusual (as well as misleading) article in that the author mixes sound scientific reasoning with illogical reasoning, and includes patterns and notions supported by data (i.e., facts) with ideas that are wildly inconsistent with the available evidence (falsehoods presented as facts). The misleading aspect comes in because the author picks what are presented as “facts” (sometimes accurate sometimes not accurate whatsoever) and compares these with other “facts” to make a point, but the comparison often has no real relevance to the questions or issues at hand. David Bahr, Associate Professor, Department of Physics, Regis University and Institute of Arctic and Alpine Research, University of Colorado I have rarely read such a misleading and factually inaccurate article. This is not science journalism and has no place in a magazine that purports to be a leading source of reliable news. It cannot qualify as an informed or informative opinion piece, and Forbes does their readers a great disservice by allowing the publication of blatant falsehoods. The author -James Taylor- has no understanding of the important distinctions between polar sea ice (floating on an ocean) and polar ice sheets (grounded on land), and he confuses their role in sea level rise. Despite Taylor’s protestations, the temporary expansion of Antarctic sea ice (which the author embarrassingly confuses with the expansion of an ice sheet) is well understood in the context of climate change, as is the significant reduction of Arctic sea ice which the author misleadingly understates. Taylor wrongly equates the existence of Antarctic sea ice with a lack of sea level rise. In fact, floating and melting sea ice cannot contribute to sea level rise, any more than floating and melting ice cubes can cause a glass of water to overflow. By erroneously focusing on sea ice, the author misdirects the reader and thereby conveniently overlooks the two largest current contributors to sea level rise, thermal expansion of oceans and melting glaciers. Mountain glaciers in particular (including those in Glacier National Park as discussed by Taylor) are receding at an unprecedented and increasing rate that has been repeatedly and undeniably linked to man-made climate change. The glaciers’ rapidly increasing contribution to sea level rise is unassailable. Taylor makes numerous unsubstantiated and entirely non-scientific value judgements about the benefits of climate change, and then he very inappropriately presents these value judgements as logical evidence. Among many egregious examples, the author touts the unproven benefits of increased plant growth as glaciers recede. This is in contrast, for example, to peer-reviewed research showing that as glaciers melt there will be a loss of fresh drinking water to a significant percentage of the world’s population. Taylor’s uncorroborated value judgements should not be presented as if they are on equal footing with facts, and this is a very misleading tactic hiding behind his so-called presentation of science. I could go on at length about the numerous falsehoods, misrepresentations, misdirections, cherry-picked data, cherry-picked research, and appalling logic in this article, but this sampling is sufficient to demonstrate Taylor’s failure to understand and competently write about climate change. REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. William Anderegg Associate Professor, University of Utah: This article wins the Olympic gold for cherry-picking data, misleading claims, and a long list of scientifically unsupported assertions. Sarah Perkins-Kirkpatrick Research Scientist, Climate Change Research Centre, The University of New South Wales: Absolutely appalling. Not based on credible scientific publications. Cherry picking of data and results. Use of incorrect or ambiguous language to confuse reader and to support cherry-picked results. Alexis Berg Research Associate, Harvard University: This is a deeply flawed article, scientifically. The author tries to refute a document by the Environmental Defense Fund listing 10 effects of global warming that may be unexpected (“shocking”) to the layman. To do so, he uses logical fallacies, cherry-picks studies and/or data, makes unsubstantiated claims and generally completely ignores the science of climate change and its impacts on natural and human systems. David Lobell Associate Professor, Stanford University: Repeatedly makes the erroneous argument that if something is getting better overall (e.g. health, or food production), then it’s not possible that some factor (e.g. climate) could have a negative effect. By that logic, the readers of Forbes would only worry about the economy after it was already shrinking. Lindsey Nicholson Postdoctoral research fellow, University of Innsbruck: In the sections of my expertise (glaciers, sea-level rise) the article bases its arguments on fundamental misunderstandings of basic science. The difference between sea ice made from freezing sea water, and icebergs discharged from land ice (ice sheets and glaciers) is critical. The former has no impact on sea level, while the latter does. Its a great example of where it is important to understand what the terminology refers to, and also why public articles ought to include definitions of these things to remove all ambiguity. Steven Sherwood Professor, University of New South Wales: False claims made in this article include (just to name a couple in “Lie #1”): Australia’s highest recorded temperature being >50 years ago (this Oodnadatta reading was an incorrectly logged, and was invalidated by the Bureau of Meteorology); heat waves not being attributable to global warming (several recent studies have shown precisely that they are, in the sense that such severe heat could not have occurred without the boost from human-caused global warming). Some claims (e.g. that we’ll just adapt to continued sea level rise) are as lacking in any scientific bases as the claims the author elsewhere criticises. Ilissa Ocko Climate Scientist, Environmental Defense Fund: Incredibly misleading article that takes information out of context and employs flawed reasoning. This article reveals without a doubt that the author is certainly no scientist or expert on the subject, and as such should not be considered a viable source of information. Aaron Bernstein Associate Director of the Center for Health and the Global Environment, Boston Children’s Hospital, Harvard: A reader could be fooled into believing what is written at face value but most claims articulated in James Taylor’s article are false based upon scientific research. Rasmus Benestad Senior scientist, The Norwegian Meteorological institute: Using labels such as “alarmist” does not invite to constructive debate. Furthermore, the statement “remember these are the very best arguments global warming alarmists can make” is highly subjective and not a judgement I think James Taylor is in position to make. For instance “Bats Drop from the Sky” is not one of them! Tobias Sauter Postdoctoral research fellow, University of Erlangen: This article simply ignores the essential principles of good scientific journalism: Truth and accuracy, independence, and impartiality. The article is plagued with inaccurate information and false statements about climate and glacier change. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Featured Annotations: Below is a list of scientists’ comments replying to James Taylor’s statements. “Global warming alarmists’ preferred electricity source – wind power – kills nearly 1 million bats every year (to say nothing of the more than 500,000 birds killed every year) in the United States alone. […] Killing 30 million bats every year in response to dubious claims that global warming might once in a great while kill 100,000 bats makes no sense.” Alexis Berg Research Associate, Harvard University: False dichotomy. The point of transitioning power generation away from fossil fuels is not only to save bats. Also, just to provide some context, it is “estimated that between 89 and 340 million birds die annually from vehicle collisions on U.S. roads” Sarah Perkins-Kirkpatrick Research Scientist, Climate Change Research Centre, The University of New South Wales: Australian bats are fine tuned to a specific threshold – around 42C. Once the temperature is reached they literally DO fall out of trees, and it is primarily lactating mothers and babies this happens to. The more this occurs (as what is projected under anthropogenic climate change), the more they will die, and the less they will be able to recover from what was once a very rare event. See this article, and publications by the author Just Welbergen. “Australia’s highest recorded temperature occurred more than half a century ago, … Indeed, Queensland’s 2014 heat wave paled in comparison to the 1972 heat wave that occurred 42 years of global warming ago. If global warming caused the 2014 Queensland heat wave, why wasn’t it as severe as the 1972 Queensland heat wave?” Alexis Berg Research Associate, Harvard University: Comparing particular dates in times and claiming that global warming should explain everything is a stale and discredited tactic from climate skeptics. What one needs to do is look at robust trends in the data. In his case, it shows that heat waves have increased in frequency/duration since 1950 in some parts of the world (where there is sufficient data to look at such changes), like Europe, Asia, and, yes, South-east Australia. See: Perkins, Alexander & Nairn (2012), Increasing frequency, intensity and duration of observed global heatwaves and warm spells, Geophys. Res. Lett. “Lyme Disease is much more common in northern, cooler regions of the United States than in southern, warmer regions. Asserting, without any supporting data or evidence, that a disease that prospers in cool climates will become more prevalent as a result of global warming defies objective data and common sense. Prof. Kristie L. Ebi, University of Washington: The supporting evidence is one 2008 review of the spatial dynamics of Lyme disease by Killilea et al. The authors did conclude that the presence of forests was associated with increased risk of Lyme disease. They also concluded that the reasons for variations across forested areas are poorly understood, and that significant progress is needed in identifying the determinants of spatial variation in risk and incidence. Between the year 2000 and 2015, there has been 31 publications on Lyme disease and climate change providing significantly more information. The recent US National Assessment Health Chapter concluded that: “Potential impacts of climate change on the transmission of Lyme disease include: 1) changes in the geographic distribution of the disease due to the increase in favorable habitat for ticks to survive off their hosts; 2) a lengthened transmission season due to earlier onset of higher temperatures in the spring and later onset of cold and frost;” Susan E. Pacheco, MD, University of Texas Health Science Center at Houston: 1. That Lyme disease occurs in the northeastern states does not mean that the disease process is driven by a cold environment. Indeed the ticks that spread this disease thrive in humid and relatively warm environments. This, combined with increased human outdoor activities during warmer months help explain most cases of Lyme disease occur in the summer months. It has been established that the geographic distribution of the Ixodes tick has increased with warming temperatures. 2. The authors cite an article by Killilea et al, where it is stated, in the context of spatial dynamics, that “the only environmental variable consistently associated with increased Lyme disease was the presence of forests”. This is taken out of context as climate change is not a variable in this analysis. In a more recent article, Ostfeld, the senior author of the Killilea paper, discusses the association between climate warming and increase in the distribution of the Ixodes tick. “The alarmists’ asserted national security threat depends on assertions that (1) global warming is causing a reduction in food and water supplies and (2) migrations of people to places with more food and water will increase risks of military conflict. Objective facts refute both assertions.” Aaron Bernstein Associate Director of the Center for Health and the Global Environment, Boston Children’s Hospital, Harvard: For starters, many experienced leaders—military, political, and otherwise—are extremely concerned about the threat climate change poses to security. See the American Security Project’s work on climate security. In addition, growing staple crops at higher CO2reduces their nutritional value. While some regions have benefited from recent warming, extreme events associated with climate change have already destabilized the world food system. Models consistently show that climate change will adversely effect crop output. The best available science also shows that even in the past few decades climate change has reduced food production, by as much as 5 billion dollars per year as of 2002. “U.S. Forest Service data show pine beetle infestations have recently declined dramatically throughout the western United States.” William Anderegg Associate Professor, University of Utah: This is true, but it does not reflect a lack of climate change influence on beetles. When one actually examines the US Forest Service reports data, they state that the infestation rates are falling in many regions because they have already killed most of their host pine species. This is hardly good news. Regents Professor Steven W. Running, University of Montana: Climate change has accelerated insect epidemic mortality in western forests. I would refer readers to the 2014 National Climate Assessment, specifically the Chapter on Forests for full details. “Severe storms, floods and agricultural losses may cost a great deal of money, but such extreme weather events—and their resulting costs—are dramatically declining as the Earth modestly warms.” Emmanuel Vincent Founder & Executive Director, Science Feedback: To the best of my knowledge, there is no scientific evidence showing that severe storms and flood are “dramatically declining“. Such a strong statement should be supported by a strong reference. To the contrary, as the atmosphere warms, water vapor content increases, and this is allowing more extreme rainfall events, notably during hurricanes. see eg: Trenberth (2011) Changes in precipitation with climate change “Calling attention to anecdotal incidents of icebergs breaking off the Antarctic ice sheet, while deliberately ignoring the overall growth of the Antarctic ice sheet is a misleading and favorite tactic of global warming alarmists” Martin Truffer, Professor, University of Alaska Fairbanks: The author does not know what he is referring to when he says ‘the Antarctic Ice Sheet’. What has been expanding is the extent of sea ice around Antarctica, not the Antarctic Ice Sheet. While icebergs routinely break off Antarctica, the release of this particular iceberg was significant. Iceberg calving from Pine Island Glacier has been occurring at ever increasing rates, and the line of contact between the glacier and the ocean (the grounding line) keeps retreating. It looks even worse at nearby Thwaites Glacier that is now on the brink of unstable retreat, or has already crossed that threshold. See, for example: Joughin et al (2014). Marine Ice Sheet Collapse Potentially Underway for the Thwaites Glacier Basin, West Antarctica. The basins of Thwaites and Pine Island Glacier hold enough ice to raise global sea level by 1.5 m. “alarmists here are taking overwhelmingly good news about global warming improving plant health and making it seem like this good news is actually bad news because healthier plants mean more pollen.” Susan E. Pacheco, MD, University of Texas Health Science Center at Houston: 1. There is definite scientific evidence demonstrating that warmer temperatures and higher CO2 levels increase the length of the pollen season, and the allergenicity of pollens. 2. Elevated pollen counts have been associated with increase in emergency room visits in patients with asthma."
https://science.feedback.org/review/forbes-james-taylor-updated-nasa-data-polar-ice-not-receding-after-all/,-2,"Forbes, by James Taylor, on 2015-05-19.",,“Updated NASA Data: Global Warming Not Causing Any Polar Ice Retreat”,,,,,"This article has been read more than 660,000 times since it was published in May, making it Forbes’s most read article on climate in 2015. So how accurate was it? Not accurate at all. According to the reviewers, this article contains numerous factual errors and flawed logic. The author fails to distinguish between sea and land ice, and the Arctic and Antarctic. Taylor’s conclusion, which contradicts the observed signal of global warming on polar ice, is misleading.See all the scientists’ annotations in context If the link does not work due to the high number of ads on Forbes, install Hypothesis bookmarklet or extension in your browser and switch it on from the article page. UPDATE (6 September 2019): On an unspecified date, Forbes retracted this post. A note on the article now reads: “After review, this post has been removed for failing to meet our editorial standards. We are providing our readers the headline, author and first paragraphs for context only. We regret any inconvenience or confusion.”GUEST COMMENTS: Jennifer Francis, Research Professor I, Department of Marine and Coastal Sciences, Rutgers University As is clearly explained in a recent article from Carbon Brief, sea ice behavior in the Arctic and Antarctic is responding to climate change in different ways, and we know why. In the graph below, it is obvious that Arctic sea ice is disappearing at a much faster rate than Antarctic ice is increasing. Numerous studies have concluded that Arctic ice loss results from a combination of thinning due to greenhouse-gas warming, natural events that flushed thick ice out of the region, and various positive feedbacks (amplifying effects) that augment the ice loss. Climate models cannot reproduce observed Arctic sea ice loss without including the buildup of greenhouse gases in the atmosphere. On this topic the science is settled. In Antarctica, sea ice varies from year to year much more than it does in the Arctic because its boundaries are not confined by land, as they are in the Arctic. The Southern Ocean sea ice is free to move with the ferocious winds and strong ocean currents that prevail there and cause the large variations. In recent years, the amount of sea ice in winter (when it has a relatively small effect on the global energy balance because there’s no sunlight) has increased, but much less than the amount lost in the Arctic. This increase has been caused by stronger storms (related to a recovering ozone hole) and fresher surface waters (owing to melting of Antarctica’s ice shelves). Because the Antarctic is so much colder than the Arctic, it takes a much larger temperature increase to affect the sea ice, but eventually global warming will cause this sea ice to decline, as well. Readers of articles such as this that claim to refute decades of peer-reviewed science must arm themselves with a healthy dose of skepticism — the good kind. Dig deeper, inform yourself, and don’t take one non-scientist’s take as gospel just because it supports a position that you hope is true. Arctic and Antarctic annual average sea ice extent (million square kilometres), from 1979 to present, against a baseline of 1981-2010. Source: Monthly data available from NOAA, via the NSIDC. Julienne Stroeve , Senior Research Scientist, National Snow and Ice Data CenterThe article is misleading and completely incorrect. It appears that the article is lumping together sea ice and ice sheets, although perhaps the author does not know the difference between sea ice and the ice on Greenland and Antarctica. Several outright false statements persist in the article: 1) Sea ice from earlier satellites, submarines, aircraft, whaling log reports, etc. do not show that polar ice caps were more extensive in 1979 than the 1920s. Sea ice also did not remain at 1979 levels until 2005. There is no NASA data that shows this. Arctic sea ice has been declining in all calendar months and in all regions of the Arctic (except for slight increase in the Bering Sea during winter) since the satellite record began, it has not recovered in any way. The Antarctic shows areas of small regional increases that are dependent on the time of year, but in contrast to the Arctic, these increases are not for all sea ice regions and they do not happen in all calendar months. 2) The author also appears confused by the fact that the sea ice grows back every winter and fails to understand the importance of weather. We do not expect each year to exhibit lower sea ice extents than the year before as sea ice responds to the weather patterns, and a particularly cold year may help keep ice around in one summer (such as in 2013). That does not imply the long-term trend is not continuing, just that there are departures from year to year along the long-term trend. Just as one shouldn’t make a big deal out of the record low in 2012, they shouldn’t point to 2013 as a recovery. 2015 shows this to be very true despite the author’s claim of a “dramatic rebound” in 2013, and the false statement that sea ice has been 5% above the 1979 average ever since 2012. 3) May 2015 does not show sea ice 5% above the 1979 average, in fact the Arctic set an all time record low for the winter maximum in 2015. And while the Antarctic had some record high summer ice, the maximum in 2015 was near average. 4) There is no definition of what the author means by land ice, but records show increased melting of Greenland and parts of Antarctica, that together lead to significant increases in global sea level.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Twila Moon Research Scientist, University of Colorado, Boulder: This article was overwhelmingly misleading. The author consistently applied incorrect methods to come to false conclusions using real data. Terms were also used incorrectly, increasing confusion. Ken Mankoff Senior Scientist, Geological Survey of Denmark & Greenland: This article discusses land and sea ice interchangebly and appears to confuse the two. This is a fundamental error, equivalent in other fields to confusing house and senate, or an artery and vein. Ron Kwok Senior Research Scientist, Jet Propulsion Laboratory, California Institute of Technology: In this article, The Arctic and Antarctic ice cover are totally muddled. Most of the trends quoted are of the Arctic, even though the mechanisms controlling Arctic and Antarctic ice differ and should be considered carefully and separately. Robert Grumbine Physical Scientist, National Oceanic and Atmospheric Administration: Cherry picking, misrepresentation, distortion. Substituting personal value judgements for scientific conclusions. Ilissa Ocko Climate Scientist, Environmental Defense Fund: The author asserts bold statements that are not whatsoever backed up by science and scientific research. The article is misleading and flat out incorrect, with flawed reasoning throughout. Jan Lenaerts Assistant Professor, University of Colorado, Boulder: This article claims that global sea ice has not decreased since 2012, by ‘cherry-picking’ data comparing short term signal to a long-term trend. It contains many invalid and unjustified claims. Rasmus Benestad Senior scientist, The Norwegian Meteorological institute: The article contains a number of inaccuracies and mixes up different aspects. The sea-ice reduction in the Arctic is a summer-time phenomenon, whereas the Antarctic sea-ice is a winter-time condition. Thus, the sea ice at the two poles involve different mechansisms, in addition to playing out in different geography (the North pole is an ocean basin surrounded by land, whereas the South pole is land surrounded by sea). It’s very naive to think that ice is just ice. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-away: The statements quoted below are from James Taylor; comments and replies are from the reviewers. While sea ice extent varies from year to year, global sea ice extent has declined since satellite records began in 1979.“Updated data from NASA satellite instruments reveal the Earth’s polar ice caps have not receded at all since the satellite instruments began measuring the ice caps in 1979.” Dr. Robert Grumbine, National Oceanic and Atmospheric Administration: Incorrect on at least two levels. What he compares is ice at a particular time in 1979 with ice at a particular time in 2015. Today (23 October 2015), the figure is negative; ice is again below the long term average, and below values at any time in 1979. The second and more important level on which this is wrong is that for examining long term trends, scientists use all the data, not just two particular days out of 36 (and growing) years of data. The long term trend is negative. Both of these can be verified by going to Cryosphere Today, at the University of Illinois. See also Cryosphere Today’s response to this article. Twila Moon Research Scientist, University of Colorado, Boulder: This is flat out false. NASA has an excellent visualization and graph of Arctic sea ice decline since 1979. Antarctic sea ice, on the other hand, has had some expansion. However, this expansion does not negate climate change, as explained in this news article. “Since the end of 2012, moreover, total polar ice extent has largely remained above the post-1979 average.” Ken Mankoff Senior Scientist, Geological Survey of Denmark & Greenland: Extent is a measure of area, but volume also matters. The short-term area increase is due to new thin ice. This ice melts more easily than the older thicker ice which used to occupy this area. See this news article. “The late 1970s marked the end of a 30-year cooling trend.” Ken Mankoff Senior Scientist, Geological Survey of Denmark & Greenland: Also misleading. Natural variability is still part of the ongoing climate warming. While the late 1970s were cooler than the years around 1904, it was not a continuous cooling, as seen below. You can also see in this figure that late 1970s temperatures were still high in comparison to the previous 120 years. “As a result, the polar ice caps were quite likely more extensive than they had been since at least the 1920s.” Dr. Robert Grumbine, National Oceanic and Atmospheric Administration: Mr. Taylor should publish his research on what the sea ice area was. Otherwise, he is simply stating his opinion on a technical topic. And he his not an expert in this topic. “Beginning in 2005, however, polar ice modestly receded for several years.” Dr. Robert Grumbine, National Oceanic and Atmospheric Administration: Mr. Taylor’s value judgement of ‘modest’ recession is, again, hampered by not being expert in sea ice. A ‘modest’ change in body temperature from 98.6 F to 108.6 F (only 10 degrees, the outside temperature changes by 30 degrees some days) would be fatal. ‘Modest’ is decided by examining the thing you’re studying. “Total polar ice area—factoring in both sea and land ice—had receded by much less than 10 percent, but alarmists focused on the sea ice loss as ‘proof’ of a global warming crisis.” Ilissa Ocko Climate Scientist, Environmental Defense Fund: Lumping all of the polar ice together is not very insightful. First – land ice and sea ice are very different; land ice accumulates for thousands of years while sea ice is a seasonal and inter-annual process. Land ice in Antarctica is melting rapidly which means that water stored for centuries is entering the oceans raising sea level. However, sea ice in Antarctica is slightly gaining likely because of mixing processes between melting freshwater and ocean saltwater. The sea ice in Antarctica has little impact on the energy balance and does not change sea level. One must distinguish between the two different processes of land and sea ice. Second – Arctic and Antarctic processes are very different. The Antarctic is much cooler than the Arctic, as it is very isolated from the rest of the world with a current that prevents some of the warming from reaching the area. Even though the Antarctic air and sea are warming, because the Antarctic sea ice melts every summer anyways, and the Arctic’s does not, Arctic sea ice melt strongly impacts the energy balance. Sea ice volume in the Arctic has decreased by 50% from 1979 to today – data from the Polar Science Center. Third – polar ice area is not nearly as telling as polar ice mass or volume, so the metric that the author uses is extremely misleading. “receding polar ice caps have little if any negative impact on human health and welfare, and likely a positive benefit” Ilissa Ocko Climate Scientist, Environmental Defense Fund: This is not true. Polar ice caps (land ice) have already contributed to sea level rise that has impacted coastal communities all over the world. Currently, mean sea level rise (7.5 inches globally; 1 foot off the Northeast U.S.) manifests its worst impacts through storm surges that are much higher than they would otherwise be. … Further, Arctic communities have already been impacted by melting ice and permafrost. One resident of an Eskimo community stated in 2012 that “Not that long ago the water was far from our village and could not be easily seen from our homes. Today the weather is changing and is slowly taking away our village. Our boardwalks are warped, some of our buildings tilt, the land is sinking and falling away, and the water is close to our homes. The infrastructure that supports our village is compromised and affecting the health and well-being of our community members, especially our children.” Coastal erosion has threatened many communities, and standard defensive adaptation strategies, such as rock walls, sandbags, and riprap, have been unsuccessful. High costs to relocate have prevented all but one Alaskan village to escape."
https://science.feedback.org/review/andrew-freedman-mashable-hurricane-patricia-global-warming/,1.4,"Mashable, by Andrew Freedman, on 2015-10-23.",,“How Hurricane Patricia became the strongest hurricane on record so quickly”,,,,,"This article is accurate and based on comments from scientists with actual expertise in the study of climate influence on intense hurricanes. It describes the roles of El Niño, greenhouse warming, and other physical factors at play in Hurricane Patricia’s spectacular intensification.See all the scientists’ annotations in contextGUEST COMMENTS: James Kossin, Research Scientist, NOAA’s Center for Weather and Climate Nice piece. Well written and accurate, with a good variety of quotes. Doesn’t over-reach or sensationalize, and presents some aspects of what we know in a clear useful way. In fact, the connection between climate change and Patricia may be a bit understated and overly conservative, as the connection between climate change and the most extreme hurricanes was not discussed.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Karthik Balaguru Scientist, Pacific Northwest National Laboratory: The article is well-written and explains the potential scientific reasons behind the rapid intensification of Hurricane Patricia reasonably. Hamish Ramsay Lecturer, Monash University: A well written and balanced article that draws on a range of scientific opinion from well-established climate scientists, hurricane specialists and forecasters. The article provides a nice summary of the major physical factors at play, while also highlighting the issues and challenges to do with detection and attribution of extreme events such as this. Daniel Cohan Associate Professor, Rice University: The author has undertaken a superb effort to incorporate the instant reactions of leading experts in tropical cyclone formation. The article provides a nuanced explanation of current scientific understanding and uncertainty regarding the relative roles of El Niño and greenhouse warming in intensifying Pacific storms. Dan Chavas Assistant Professor, Purdue University: It’s a very nice article overall, as it is more an organized survey of scientists rather than a non-science author trying to make a scientific argument. My concerns lie only with the content provided by one of the scientist contributors (Kevin Trenberth), which is not the author’s responsibility. Emmanuel Vincent Founder & Executive Director, Science Feedback: A good description of what scientists think about the influence of climate change on intense hurricanes like Patricia. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time."
https://science.feedback.org/review/matthew-francis-forbes-even-without-drastic-predictions-coasts-are-in-danger/,1,"Forbes, by Matthew Francis, on 2015-07-28.",,“Climate Change Will Cause Increased Flooding In Coastal Cities ”,,,,,"This article provides a fair and balanced discussion of two recent scientific studies on the magnitude of the sea level rise that can be expected this century as a result of human-induced climate change.See all the scientists’ annotations in context If the link does not work due to the high number of ads on Forbes, install Hypothesis bookmarklet or extension in your browser and switch it on from the article page.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Tad Pfeffer, Professor of Glaciology, University of Colorado A clear statement of the content of a controversial paper, with an accurate description of the source of controversy. I think this is a good piece of science journalism, in which the author gives an even-handed account of the position taken in the Hansen et al piece, and also describes the informed opposition to the Hansen’s conclusions, as articulated in Kevin Trenberth’s response (also cited in the piece). The author’s scientific credentials show in his writing, even though he does not come down on one side or another of the controversy. David Bahr, Associate Professor, Department of Physics, Regis University and Institute of Arctic and Alpine Research, University of Colorado The article discusses a manuscript that is still under “open access” review, so naturally there is still significant (and public) discussion about the details among scientific reviewers. Overall the article is accurate, though some of the language is a little skewed. For example, the author says climate deniers “may not have science on their side,” but that should be “do not have science on their side.” Likewise, by calling Hansen’s work “alarmist predictions,” the author uses language that is common to climate deniers and introduces a subtle bias that is unfounded until the review process is complete. Nevertheless, the article is reasonable, and it correctly states that sea level rise is a real problem regardless of this particular Hansen publication. Ted Scambos, Senior Research Scientist, National Snow and Ice Data Center The article is accurate enough in its discussion of the threat, and the Hansen paper, but understates the nature of the concerning issues with the Hansen et al. extrapolation and concluding estimates. Hansen et al. estimates are based on a somewhat adhoc amplification of the contribution from the ice sheets based on the past two decades’ observations. If we have seen an approximate doubling every decade, then (having eight decades left in this century) we might anticipate at least a 2^8 (256-fold) increase in mass loss from the ice by 2100 – says Hansen et al. This ignores fundamental issues with the mechanics of this ice loss, e.g. in glacier speeds or in surface melt rates. This was discussed in part in an earlier paper by Pfeffer et al., in 2008. Rasmus Benestad, Meteorologisk Institutt The article does not explain that the IPCC numbers tend to exclude collapse from landfast ice, wheras Hansen et al place a great deal of emphasis on land ice. Also it is diverted by an argument about ENSO (El Niño), which is not relevant for the analysis by Hansen et al, as ENSO involves much shorter time scales. James E. Neumann, Industrial Economics The author generally characterizes two important new studies accurately, and correctly references other relevant work and the major conclusions of that work. Alexis Berg, Postdoctoral Research fellow, Columbia University This article reports on two recent papers about climate change and sea-level rise. The author places the articles in the context of current scientific thinking rather accurately. He should have mentioned that Hansen’s paper is not published yet, and could also have provided more quantitative information on the topic.Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time."
https://science.feedback.org/review/andrew-freedman-south-carolina-flooding-climate-change/,1.3,"Mashable, by Andrew Freedman, on 2015-10-06.",,“South Carolina flooding is the type event climate scientists have warned about for years”,,,,,"This Mashable article does a good job at describing the relationship between the flooding in South Carolina and climate change. Long-term trends show an increase in the frequency of heavy downpours in the US, and this increase is consistent with the consequences of climate change. There is still debate, however, over attributing specific extreme rain events to climate change. Some scientists argue that by increasing the amount of moisture in the atmosphere, global warming has an impact on all extreme rain events. Not all scientists agree with this conclusion, however, and Andrew Freedman makes this clear in his article.See all the scientists’ annotations in contextGUEST COMMENTS: Thomas Mote, Professor, Department of Geography, University of Georgia I believe the article addresses our current understanding of the science and is a balanced response. The article discussed the unique juxtaposition of an upper-level low and hurricane that was the direct cause of the event, but also directly addresses the role of the increase in atmospheric water vapor available for enhancing rainfall. The article also discusses the potential role of high latitude blocking highs (such as occurred with Hurricane Sandy), but, appropriately, does not dwell on that as a leading mechanism. I also appreciate the different perspectives on attribution studies and how they might apply to this situation. Note: For the reader interested in further analysis about the influence of climate change on South Carolina flooding, Dr. J. Marshall Shepherd (Professor at the University of Georgia) recommends the article by Chris Mooney in the Washington Post. Dr. Shepherd says, “It pretty much sums up what I would say about South Carolina flooding and climate change.”REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Dargan Frierson Associate Professor, University of Washington: Water vapor content has increased in a warmer climate, and this is leading to more extreme rainfall events around the world. It’s tricky to evaluate the contribution of climate change to a particular weather event, but generally speaking, the author provides an accurate summary of the challenges of this research, and the range of scientific thinking about it. Victor Venema Scientist, University of Bonn, Germany: This is a complicated topic and the author honestly describes many caveats. Still the reader may get the impression that the changes in precipitation are larger than they most likely are. Jim Kossin Research Scientist, NOAA's Center for Weather and Climate: The statements and quotes are defensible but also vague and quite broad in how one thing may be related to another. Consequently, the article does not provide much scientific insight. The lack of specificity in “connecting the dots” leads to a somewhat unsubstantial message. Alexis Berg Research Associate, Harvard University: In my view this article presents a well-documented and balanced view of what can, or cannot, be said currently about extreme precipitation events and global warming in general, and about this recent event in South Carolina in particular. I appreciate the author’s effort to get the input of several climate scientists on the latter. Ilissa Ocko Climate Scientist, Environmental Defense Fund: Comprehensive overview of the state of the science, including discussion of areas we know well and areas that are still being actively researched. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time."
https://science.feedback.org/review/betsy-mccaughey-wake-up-obama-climate-change-has-been-happening-forever/,-2,"New York Post, by Betsy McCaughey, on 2015-09-07.",,"“Wake up, Obama, climate change has been happening forever”",,,,,"The scientists unanimously qualify this article as misleading and flawed in its reasoning. The author asserts that “many scientists are predicting the onset of two or three centuries of cooler weather—which would mean bigger glaciers.” As the scientists point out, however, glaciologists have collected “crystal clear” evidence for accelerating glacier melt and retreat, which scientists overwhelmingly attribute to human-induced global warming, and scientific consensus warns that a continued rise in atmospheric greenhouse gas concentrations will produce further global warming.See all the scientists’ annotations in contextGUEST COMMENTS: Martin Truffer, Professor of Physics, University of Alaska Fairbanks This article seems to proclaim that because there is natural variability in climate, there can’t possibly be human-caused climate change. This is like saying that sea-level change cannot be due to ice loss, because sea level goes up and down every day with the tides, without ice melting. The fact is that global temperatures keep rising, and the carbon dioxide content of the atmosphere has reached a level that is unsurpassed during the time human civilization has existed. We are in the middle of conducting the greatest climate experiment. Uncertainties in models mean that we don’t know exact outcomes, but the forcing of greenhouse gases is understood sufficiently well that the risk of large changes in climate is very high. Undoubtedly, natural variability means that there will be cooler trends that interrupt the general warming, but it also means that there will be times with unusually high rates of warming. Scientists who proclaim to know that we are heading into decades of cooling stand on very thin ground. Stephan Harrison, Associate Professor in Quaternary Science, University of Exeter This article is highly misleading and biased. It fails to recognise that scientists have good understanding of the ways in which climate change occurs and the ways in which we can differentiate between natural variability in the climate and climate change produced by human greenhouse gas emissions. Obama was also correct in using Exit Glacier as an example of how contemporary climate change is leading to the retreat of glaciers. This pattern of glacier melt is seen in all of the world’s glaciated mountain regions. Arguing whether one glacier started its recession slightly earlier or slightly later than others is to miss the point. The article also tries to suggest that Arctic warming is not new. What it fails to reveal though is that the recent warming covers the whole of the Arctic region; previous warming was much more regional. Finally, the article claims that scientists are predicting a long period of global cooling. While climate change does not mean that all regions of the world will warm uniformly, the overwhelming scientific consensus is clear that a continued rise in atmospheric greenhouse gas concentrations will produce continued global warming. This view is supported by all the world’s major academies of science and by the recent reports of the Intergovernmental Panel on Climate Change. David Bahr, Associate Professor, Department of Physics, Regis University and Institute of Arctic and Alpine Research, University of Colorado Betsy McCaughey incorrectly confuses the historically slow retreat of the Exit Glacier with its vastly more rapid retreat over the last 25 years. Manmade climate change is directly related to the historically unprecedented and rapid melt of Alaskan glaciers. Scientific study after study shows that most of the world’s glaciers are melting at an ever-increasing rate that cannot be explained by natural cycles alone. Only human activities could generate the speed-up in melt that we have observed over the last 25 years in Alaska and around the world. Glaciologists have collected tens of thousands of measurements from glaciers, dating back over 120 years, and the evidence of accelerating glacier melt and retreat in response to manmade warming is crystal clear. Any other conclusion is willfully ignoring the data, the facts, and the conclusions of the entire glaciological community. Ignoring this level of certainty about the human causes of melting of glaciers is analogous to believing that the Earth is flat, all evidence to the contrary. Mauri Pelto, Professor of Environmental Science, Nichols College Alpine glaciers did retreat rapidly during the first half of the century, but not from 1950-1980 when many alpine glaciers including several in Glacier Bay, Alaska did advance. The volume of Greenland and Antarctic Ice Sheets was also stable during this period. Today, it is the ubiquitous and rapid volume loss on glaciers that is remarkable, and one of the many different lines of evidence that have convinced the vast majority of scientists that the current warming is caused by man. Glaciers in equatorial and arctic latitudes, wet and arid climates, large and small, ending in lakes or the ocean are almost all retreating. Out of the 250 glaciers I have worked on, at present 242 are retreating, six have disappeared and one is stationary.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Alexis Berg Research Associate, Harvard University: This article rehashes a tired old argument that because natural forces have caused climate change in the past, current climate change is no big deal. In fact, every line of evidence now points to man-made greenhouse gas emissions as the primary driver of ongoing (and projected) climate change. The article also tries to pin the “global warming theory” on president Obama, while the reality is that it reflects the consensus diagnosis of the climate science community. Jan Lenaerts Assistant Professor, University of Colorado, Boulder: An extremely subjective, unsubstantiated article. It includes several misleading and flawed statements and cites irrelevant experts. Andreas Schmittner Associate Professor, Oregon State University: Contrary to overwhelming scientific evidence and conclusions of the vast majority of climate scientists, the article claims that climate will be cooling in the future and that the recently observed warming is not caused by humans. It is misleading in suggesting uncertainty and doubt about human causes of climate change, whereas in reality there is very little uncertainty and doubt on that point. Joseph Shea Assistant Professor, University of Northern British Columbia: The article contains many misleading and simply false statements about climate and glacier change. Ilissa Ocko Climate Scientist, Environmental Defense Fund: This article is plagued with inaccurate information, flawed logic, and quotes from individuals who lack climate science merit. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time."
https://science.feedback.org/review/tom-harris-deceptive-temperature-record-claims/,-1.9,"The Washington Times, by Tom Harris, on 2015-08-23.",,“Deceptive temperature record claims”,,,,,"Our reviewers unanimously characterize this article as misleading and in disagreement with elementary science. The author uses a scientifically baseless argument to support his claim that an average global temperature for the surface of the Earth is a meaningless quantity.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Shaun Lovejoy Professor, McGill University: The argument has two parts: a) that the accuracy of the measurements is too low to claim a record, b) that the global temperature is meaningless. a) is an affirmation that is not supported by the facts (the actual accuracy is indeed enough to affirm that the month is hottest – or at least amongst the hottest). b) This is a repetition of a sophisticated but irrelevant argument put forward many years ago by Essex and McKitrick. Victor Venema Scientist, University of Bonn, Germany: The article is deceptive and claiming that a global average temperature does not exist is simply wrong. Dargan Frierson Associate Professor, University of Washington: The only deception here is by the author, who uses a false scientific claim (that global average temperature does not exist) to back up his ridiculous assertion that global warming doesn’t matter. Andreas Schmittner Associate Professor, Oregon State University: The article claims that global mean temperature is not a meaningful measure of climate, contrary to climate science and its standard practices. It is a typical denial argument that has no foundation in science. Alexis Berg Research Associate, Harvard University: This article recycles old, specious skeptic talking points about how the Earth’s global temperature does not exist, cannot be computed and/or is irrelevant to its inhabitants. All long-debunked nonsense. John Abraham, Professor, University of St. Thomas This article makes several inaccurate claims and the authors demonstrates a nearly complete lack of knowledge about measurement of the Earth’s climate. The claims about temperature accuracy, ocean measurements, thermodynamics and others are just plain wrong. Andreas Klocker Physical Oceanographer, University of Tasmania: Whereas this article claims that ‘Warmest month announcements have no scientific basis’ I would say that this article does not have any scientific basis. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from the article; comments and replies are from the reviewers. 1.Through careful analysis, researchers effectively track changes in global temperatures. “This is the distance between Ottawa, Canada, and Myrtle Beach, S.C. cities with very different climates. Yet, according to NASA, only one temperature sensing station is necessary for the two cities and the vast area between them to be adequately represented in their network.” Victor Venema Scientist, University of Bonn, Germany: One of the reasons why climatologists prefer to work with “anomalies”, deviations from the typical climate, is that anomalies are similar over large regions, especially when it comes to averages over longer periods. I guess everyone still remembers that last winter the entire East Coast was colder than usual, while the West Coast was warmer than usual. Thus while it naturally was absolutely warmer in the South, regions of the East coast with different climates still had similar temperature anomalies, this is why a station at a given point is representative of the temperature anomaly in a large region around that point. Alexis Berg Research Associate, Harvard University: This is an old skeptic talking point that has been discussed a thousand times. The basic point is the difference between temperature anomalies and absolute temperatures. See for instance this NASAwebpage, which indicates: “The GISTEMP analysis concerns only temperature anomalies, not absolute temperature. Temperature anomalies are computed relative to the base period 1951-1980. The reason to work with anomalies, rather than absolute temperature is that absolute temperature varies markedly in short distances, while monthly or annual temperature anomalies are representative of a much larger region. Indeed, we have shown (Hansen and Lebedeff, 1987) that temperature anomalies are strongly correlated out to distances of the order of 1000 km.” See also this article by Real Climate : “the basic issue is that temperature anomalies have a much greater correlation scale (100’s of miles) than absolute temperatures – i.e. if the monthly anomaly in upstate New York is a 2ºC, that is a good estimate for the anomaly from Ohio to Maine, and from Quebec to Maryland, while the absolute temperature would vary far more. That means you need fewer data points to make a good estimate of the global value.” “In their award winning book, ‘Taken By Storm’ (2007), Canadian researchers Christopher Essex and Ross McKitrick explain: ‘Temperature is not an amount of something [like height or weight]. It is a number that represents the condition of a physical system. In thermodynamics it is known as an intensive quantity, in contrast to quantities like energy, which have an additive property, which we call extensive in thermodynamics.’” Andreas Schmittner Associate Professor, Oregon State University: Temperature and heat (energy) content are closely related such that the heat content is the temperature times the specific heat capacity and the density. Because the specific heat capacity is a constant and density variations are small compared to temperature variations the heat content is typically very closely related to the temperature of the air in the atmosphere or the water in the oceans. Thus, while this citation of Essex and McKitrick is a correct statement about the principles of thermodynamics, its use here is misleading because it does not acknowledge the close relationship between temperature and energy in practical climate applications. “Temperature, like viscosity and density, and of course phone numbers, is not something that can be meaningfully averaged. ‘Global temperature’ does not exist.” Alexis Berg Research Associate, Harvard University: According to this line of argument, one could not talk about human body temperature, because the temperature of someone’s feet is not the same as, say, their belly. Yet I am sure Mr. Harris accepts the medical relevance of the concept of fever (or hypothermia)… Victor Venema Scientist, University of Bonn, Germany: A measured temperature is always an average over time and space. The thermometer is not infinitely fast and probes a finite space. If Harris were right, you could no longer say something as simple as your bedroom being cooler than your living room. Or the Moon being colder than the Earth. 2. Continued climate change comes with serious impacts for humans and other species. “Even if you could calculate some sort of meaningful global temperature statistic, the figure would be unimportant. No one and nothing would experience it directly since we all live in regions, not the globe. There is no super-sized being straddling the planet, feeling global averages in temperature. Global warming does not matter.” Alexis Berg Research Associate, Harvard University: This is nonsense. What about the last ice age, when global temperature was estimated to be a handful of degrees (C) lower than today, and half of North America and Europe were under huge ice sheets? Of course for large changes regional temperatures are tied to the global temperature. Almost all regions are currently warming with global warming at present, and are projected to do so with further warming. Note that warming is indeed “global”, but not every place is warming at the same rate, and some few places might even experience negative trends for now (e.g., Southeast US, North Atlantic – see below, or also here). Also note that as this supposedly irrelevant global temperature is rising, a host of associated metrics/impacts are following suit: sea level is rising, ice sheets, sea ice, permafrost and glaciers are melting, species are migrating, etc. Source: IPCC Andreas Schmittner Associate Professor, Oregon State University: Global warming matters a great deal. We know that global mean temperatures are related to sea level such that a warmer planet is one with less snow and ice on land and hence higher sea level."
https://science.feedback.org/review/brad-plumer-el-nino-explained-why-this-years-could-be-one-of-the-strongest-on-record/,1.7,"Vox, by Brad Plumer, on 2015-08-17.",,"“El Niño, explained: Why this year's could be one the strongest on record”",,,,,"Scientists unanimously qualify this article as accurate and informative. The article contains useful information for readers who are interested in learning about the ongoing El Niño event. The author correctly emphasizes the probabilistic nature of the impact of El Niño events on climate—the current El Niño, for instance, increases the odds of a rainy winter in California, but does not make it a certain outcome.See all the scientists’ annotations in context GUEST COMMENTS: Wenju Cai, Principal Research Scientist, Commonwealth Scientific and Industrial Research Organisation (CSIRO) This article is educational, logical, and useful to interested readers who want to know about the current El Niño, and/or to learn about El Niño and its impacts. The information flow-structure is also well thought out. REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Ailie Gallant Research Fellow, Monash University:This is a great article on the current El Niño and explainer on how El Niños often affect global climate, as well as regional climates around the world. The author has done a great job of providing caveats that all El Niños are different and that not every El Niño will bring rain or drought (depending on where you are) but think of it as “tipping the scales” towards those states. I think the author has done a good job of not overselling the current El Niño given that we’re not sure exactly what the impacts will be until they happen. A nice explainer from Vox. Julien Emile-Geay Assistant Professor, University of Southern California:A very well-informed piece, as scientifically accurate as can be for a didactic piece, and touching on all the impacts that people care about. I wish all climate reporting were half as good! Michelle LHeureux Scientist, US National Oceanic and Atmospheric Administration:Brad wrote a very solid and informative article on this current El Niño. He provides a clear definition of El Niño and its potential impacts, and he also managed to communicate several more nuanced elements that many El Niño articles miss when they are promoting “Godzilla.” In particular, I appreciate how he discusses that even though El Niño is quite significant, there is still uncertainty in the ultimate impacts on U.S. temperature and precipitation. Predicting climate months in advance is about making bets (favoring certain odds) because no impact is ever guaranteed. With that said, this upcoming winter will likely be quite interesting! Eric Guilyardi CNRS Research Director, Université Pierre et Marie Curie & Professor, University of Reading:This is relatively well written piece that does explain the current El Niño event and the broader context. The links are helpful if one wants to understand more."
https://science.feedback.org/review/the-telegraph-christopher-booker-arctic-ice-has-made-fools-of-warmists/,-2,"The Telegraph, by Christopher Booker, on 2015-07-25.",,“How Arctic ice has made fools all those poor warmists”,,,,,"Christopher Booker’s article claims that sea ice behavior contradicts the predicted effects of climate change, but his argument contains major scientific inaccuracies. It uses anecdotal claims as evidence, short-term year-to-year changes to dismiss long-term trends, and builds on cherry-picked information to reach its conclusions. In reality, the long-term trend of sea ice loss is clear, and mass loss from ice sheets is contributing to sea level rise.See all the scientists’ annotations in contextGUEST COMMENTS: Julienne Stroeve Senior Research Scientist, University College London: The writer fails to understand interannual variability. Long-term ice extent decline and ice volume decline does not mean each year will be lower than the year before, but that the long-term trend is towards less sea ice and thinner ice. The fact that the ice thickness increased from the record low in 2012 is no surprise since there was more ice left over in summer 2013 and 2014. This does not signal a “recovery” as the ice is still much thinner than it was in the 1980s and 1990s. It is simply a reflection of interannual variability, in particular a cooler summer in 2013 that resulted in significantly less ice melt that year. Note that the thickness did not increase by a third, the total ice volume (thickness x area) increased. The article contains numerous scientific errors as well as errors in understanding basic physics and how things are measured. For example, the author incorrectly states that you cannot measure thick ice with electromagnetic induction instruments and that instead a tape measure was needed. In fact the reverse is true, if the ice is too thick, it’s too hard to drill through the ice and measure it with a tape measure. The author is also incorrect that there is more polar ice than since 1979. Global sea ice measurements do not support this statement. Finally the fact that ships get stuck in the ice is never a surprise to those working in the polar regions. Conditions vary regionally all the time and movement of ice can suddenly result in ice compression and thick ice that may trap ships.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Andreas Schmittner Associate Professor, Oregon State University: The article claims that there is more polar ice than at any time since satellite observations begun. The existing observational evidence suggests the opposite. Alexis Berg Research Associate, Harvard University: This “take” on Arctic sea-ice changes, and more generally polar ice evolution, is highly inaccurate and totally misleading. The authors goes to great lengths to try to convince readers that polar ice is doing just fine, and therefore by extension that global warming is nothing to worry about – he cherry-picks claims, tries to pass anecdotes as evidence and annual changes as representative of long-term trends. Loic Jullion Postdoctoral Research fellow, Mediterranean Institute of Oceanography: Another article cherry picking a few years or events opposing the global trend. The majority of available pieces of evidence suggest that polar sea ice is decreasing. Jonathan Lauderdale Postdoctoral Research Associate, MIT: This article is cherry picking individual years in the satellite sea ice record whilst ignoring the long term trend. It uses anecdotes of ships getting stuck in locally thick sea ice whilst ignoring the broader spatial and temporal patterns of change. It uses misleading confusion of the effect of sea ice and land ice on sea level to justify the authors opinion that climate change is one of “the longest-running farces of our modern world”. Arctic sea ice is just one thread of evidence amongst many that suggest the climate is undergoing a warming shift as a result of anthropogenic activities. Emmanuel Vincent Founder & Executive Director, Science Feedback: The article contains major inacurracies and fails to remind the broader context of polar sea-ice and land-ice evolution over the last several decades. It also builds on a few cherry-picked facts to reach its conclusions; in science one has to account for all evidences to conclude on the most likely theory. Britta Voss Postdoctoral Research fellow, U.S. Geological Survey: This article cherry-picks portions of climate records which suit the author’s argument (that changes in Arctic ice are overstated or not a matter of concern) and relies on anecdotes rather than technical analysis. Climate records cannot be considered only on a year-to-year basis because many trends develop over decades or longer. Kyle Armour Assistant Professor, University of Washington: This article contains major scientific errors in just about every paragraph. Those scientific statements that are somewhat accurate are used in very misleading ways (e.g., the expansion of Antarctic sea ice being incorrectly linked to sea level rise; and the increase in sea-ice volume over just a few years being taken as a sign of sea-ice recovery). Further, the article highlights statements made in the press and findings by scientists that have always been considered far outside the scientific mainstream, which gives me the impression that the article was written to be intentionally misleading. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time."
https://science.feedback.org/review/the-telegraph-dan-hyde-earth-heading-for-mini-ice-age-within-15-years/,-1.5,"The Telegraph, by Dan Hyde, on 2015-07-11.",,“Earth heading for 'mini ice age' within 15 years”,,,,,"The article’s central message about an imminent mini ice age is unfounded, as it’s based on an incorrect understanding of what the Maunder minimum is, and jumps to conclusions about future climate impacts.See all the scientists’ annotations in contextUPDATE (05 Aug 2015): The original article has been modified and now features a “Correction” acknowledging that “An earlier version of this article inaccurately stated that scientists have predicted bitterly cold winters in the 2030s“. Read MoreGUEST COMMENTS: David Battisti Professor of Atmospheric Sciences, University of Washington: The article is based on material in a press release for an international astronomy meeting. Nowhere in the press release is it stated that this will cause a mini ice age, or cold winters, or the Thames to freeze. The press release is limited to a study of the solar cycle. The peer reviewed literature shows that changes in solar irradiance due to sunspot cycles may cause the global average temperature to vary by up to 0.1C on an eleven year cycle. The published peer reviewed literature concludes that the Little Ice Age was primarily due to an extended period of increased volcanic activity. A recent study [in press] quantified the cause of the cooling during the Little Ice Age (1600-1850) to be primarily due to changes in volcanic activity (77%) and secondarily due to changes in greenhouse gas concentrations (13%); changes in solar output contributed only about 10% to the net cooling of the Little Ice Age.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Michael Lockwood Professor of Space Environment Physics, University of Reading: The whole argument in the article rests on the incorrect myth that the Maunder minimum caused a “mini ice age” and uses that name to draw specious implications and conclusions. Just a couple of weeks ago we made a press release about state-of-the-art climate modelling led by the Met Office (by Sarah Ineson et al., published in Nature Communications) that shows what a return to Maunder minimum conditions would (and would not do) – but that is ignored. Loic Jullion Postdoctoral Research fellow, Mediterranean Institute of Oceanography: The Author (Dan Hyde) uses a paper focussing purely on the dynamics of the Sun solar activity to extrapolate the arrival of an upcoming ice age. Unless Dan Hyde actually attended the meeting and heard the authors explicitly mentioning the impact of their findings on climate, this article is misleading. Emmanuel M Vincent Research Scientist, University of California, Merced: This article concludes on the imminence of an ice age while the initial scientists’ press release—although ambiguous—does not. Why not fact-check sensational information before publication? Britta Voss Postdoctoral Research fellow, U.S. Geological Survey: The research this article reports on does not support a “mini ice age”, and the article does not offer commentary from researchers not involved in the work or point out that the results have not yet gone through the process of peer review. Featured Annotations: Below is a list of a few statements made by Dan Hide in his article along with comments and replies made by scientists. “The earth is 15 years from a “mini ice-age” that will cause bitterly cold winters during which rivers such as the Thames freeze over, scientists have predicted.” Michael Lockwood Professor of Space Environment Physics, University of Reading: The term “mini ice age” is inherently misleading in the context of solar variations as it implies a global decrease in temperatures and at all times of year. This does not apply at all to the solar Maunder minimum. Temperature observations from central England show that summers during the Maunder minimum were, if anything, slightly warmer than average – indeed the third warmest summer in that record occurred in the middle of the Maunder minimum, just 2 years after the coldest winter. Hence there was certainly not the unremitting cold in the Maunder minimum that the term “mini ice age” implies. There is evidence that there was increased occurrence of cold winters during the Maunder minimum but this is an effect of jet stream behaviour specific to northern Europe and the USA and not a global ice age. Recent climate modelling has reproduced this effect and indicates that the inferred lower solar ultraviolet emissions during the Maunder minimum modified the jet stream such that winters in northern Europe and the USA were colder but those in Greenland/Canada and southern Europe were warmer. This was not an “ice age” of any kind. Part of the confusion exploited by this article is that there is some evidence from tree ring data for a slight global decrease in temperatures that has been called “the little ice age” but this is nothing to do with solar variations and commenced decades before solar activity fell and the Maunder minimum began and continued after it ended. Georg Feulner Senior Scientist, Potsdam Institute for Climate Impact Research (PIK): First of all, the scientists mentioned in the article have not predicted a “mini ice-age”, but an extended period of low solar activity similar to the 17th-century Maunder Minimum. The Maunder Minimum falls into a more extended period of somewhat cooler climate conditions termed the “Little Ice Age” (although this was no true “ice age”). It has thus become rather fashionable to claim that the “Little Ice Age” was caused by low solar activity, but this is not what the science says. First, the “Little Ice Age” began already way before the Maunder Minimum and ended much later. Second, low solar activity has contributed to the cooler conditions in the late 17th century, but other drivers like frequent and powerful volcanic eruptions are responsible for most of the cooling. The link from a prediction of low solar activity in the future to a “mini ice-age” is thus highly questionable.“Temperatures will fall dramatically in the 2030s.” Georg Feulner Senior Scientist, Potsdam Institute for Climate Impact Research (PIK): While regional and seasonal effects might be larger, the expected global temperature response to a future grand solar minimum similar to the Maunder Minimum is a cooling of about 0.1°C. It should be pointed out that this cooling would occur on the background of current anthropogenic warming which is about a factor of 10 larger. To claim that “temperatures will fall dramatically” is thus not really justified. It is also clear from these numbers that a future grand solar minimum (which would last only for a few decades anyway) would not save us from global warming, as we have shown in a scientific paper and explained here. The marginal temperature differences between warming scenarios with and without a future Maunder Minimum is illustrated here: Figure – Rise of global temperature for two different emission scenarios (A1B, red, and A2, magenta). The dashed lines show the slightly reduced warming in case a Maunder-like solar minimum should occur during the 21st century. The blue line represents global temperature data. Source: PIK.“In a presentation to the National Astronomy Meeting in Llandudno, she said the result would be similar to freezing conditions of the late 17th century.” Keven Roy Research Fellow, Nanyang Technological University: Dr. Zharkova’s research predicts a lower solar activity for the next couple solar cycles (explaining patterns in recent solar activity in terms of internal variability within the solar dynamo, and extrapolating them in the future), leading to a so-called “solar minimum”, but says absolutely nothing about its impact on the climate system. A link between this decreased solar activity and the climate system cannot be drawn from the research presented or from the peer-reviewed paper on which it is based: Shepherd et al. (2014), Prediction of solar activity from solar background magnetic field variations in cycles 21-23, Astrophysical JournalNotes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all released at the same time. UPDATE (05Aug 2015): Here is the list of statements that have been removed (or modified) from the original version of The Telegraph article: “River Thames could freeze over in 2030s when Northern Hemisphere faces bitterly cold winters, scientists say” [original subtitle of the article] “The earth is 15 years from a “mini ice-age” that will cause bitterly cold winters during which rivers such as the Thames freeze over, scientists have predicted.“ “[…] in such a way that temperatures will fall dramatically in the 2030s.“ “In a presentation to the National Astronomy Meeting in Llandudno, she said the result would be similar to freezing conditions of the late 17th century.“ “This had helped create a picture of what would happen in the 2030s.“ See the retracted sentences highlighted over the article."
https://science.feedback.org/review/pope-francis-encyclical-laudato-si/,0.9,"Vatican.va, by Pope Francis, on 2015-06-18.",,Pope Francis’ Encyclical Laudato Si,,,,,"Pope Francis’s encyclical rather accurately depicts the current reality of climate change. While it does contain a few minor scientific inaccuracies, and could be interpreted as understating the degree of certainty scientists have in understanding climate change impacts, the encyclical fairly represents the present concerns raised by the scientific community.See all the scientists’ annotations in contextUPDATE (25 May 2017): The Encyclicalhas been edited, clarifying oneof the statements that scientists had highlighted here. The problematic statement initially read “Concentrated in the atmosphere, these gases do not allow the warmth of the sun’s rays reflected by the earth to be dispersed in space” and has been updated to “As these gases build up in the atmosphere, they hamper the escape of heat produced by sunlight at the earth’s surface“.GUEST COMMENTS: Kerry Emanuel , Professor of Atmospheric Science at MIT The Pope’s encyclical is strongly aligned with the scientific consensus about the reality and risks posed by global warming. The most striking feature of the encyclical is its linking of environmental degradation to cultural and political decline, painting it as a moral issue, not just a practical problem.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Alexis Berg Research Associate, Harvard University: In the few passages dealing with climate science, this text does not contain major scientific inaccuracies – but it does contain some minor ones, or at least some poor choices of words. The presentation of some elements (e.g., the scientific consensus on the attribution of observed climate change) is not as clear as it could be. Andreas Klocker Physical Oceanographer, University of Tasmania: Some facts are a bit oversimplified (but not wrong), but in general a good article written for a very broad audience. Dasvinder Kambo, PhD Candidate, Queen’s University Note: I only read Chapter 1 of the encyclical. I found Chapter 1 to be a great representation of ‘popular’ scientific understanding of the effects of climate change. However, there could have been more input on the interactions of how humans in one country influence humans in others (i.e. Fossil fuel production in North America / China decreasing rainfall in west Africa/India). Britta Voss Postdoctoral Research fellow, U.S. Geological Survey: The purpose of this document was not to provide a technical description of climate science, however, the evidence presented in support of the anthropogenic footprint of environmental problems in general and climate change in particular was overall accurate and relevant. Sarah Perkins-Kirkpatrick Research Scientist, Climate Change Research Centre, The University of New South Wales: Most of the encyclical is reasonably accurate, though there are a few careless statements that could have been better explained. In general, the current scientific view is reasonably well summarized. Emmanuel Vincent Founder & Executive Director, Science Feedback: I did not spot major inaccuracies in this document as far as climate information goes. The encyclical is a good summary of human pressure on ecosystems and associated societal concerns. It is based on a state-of-the-art scientific knowledge of these issues although some statements are imprecise. Jonathan Lauderdale Postdoctoral Research Associate, MIT: The Encyclical summarized the current state of climate science well, in conjunction with a raft of other issues related to human exploitation of the natural environment. The key part of this document is bridging the gap between the scientific observations that we make, which often do not engage the public’s attention, and the moral implications of humans as guardians of our planet (whether you are religious or not, this still makes sense). As a specific point, I think the Encyclical could have been more definitive in attributing recent climate change to anthropogenic factors – mentioning the natural forcings in the context of warming seemed to be uncharacteristically overcautious. Mark Eakin Scientist, Coordinator of NOAA’s Coral Reef Watch, National Oceanic and Atmospheric Administration: This encyclical is beautifully written and largely captures the scientific consensus. It is a bit too conservative in places, especially in terms of the amount of climate change attributed to humans. Featured Annotations: The statements quoted below are from the Encyclical; comments and replies are from the reviewers. “In recent decades this warming has been accompanied by a constant rise in the sea level and, it would appear, by an increase of extreme weather events, even if a scientifically determinable cause cannot be assigned to each particular phenomenon.” Sarah Perkins-Kirkpatrick Research Scientist, Climate Change Research Centre, The University of New South Wales: It depends on the type of event. heatwaves and extreme heat events have increased since at least the 1950s1. Though tropical cyclones and drought are a bit harder to analyse since natural climate variability also plays a large role. This means there may be a signal of change due to human activity, but is more difficult to measure, due to the noise of the natural variability of the climate. Also, “attribution” can be done for specific events. this basically compares how often an extreme event of a particular magnitude and duration occurs in climate model simulations both with and without human emissions of greenhouse gases. This was first done on the 2003 European heatwave2. So it can be done, but is heavily dependent to the event you analyse, the spacial scale on which it occurs, and even the climate model/s and experimental set up you use3 1- Perkins (2012)Increasing frequency, intensity and duration of observed global heatwaves and warm spells. Geophysical Research Letters 2- Stott (2004)Human contribution to the European heatwave of 2003. Nature 3- Angelil (2014)Attribution of extreme weather to anthropogenic greenhouse gas emissions: Sensitivity to spatial and temporal scales.Geophysical Research Letters“….to combat this warming or at least the human causes which produce or aggravate it. It is true that there are other factors (such as volcanic activity, variations in the earth’s orbit and axis, the solar cycle), yet a number of scientific studies indicate that most global warming in recent decades is due to the great concentration of greenhouse gases (carbon dioxide, methane, nitrogen oxides and others) released mainly as a result of human activity.” Jonathan Lauderdale Postdoctoral Research Associate, MIT: I think this statement is unnecessarily unclear and could be cherry-picked: “The Pope says volcanic activity, Earth’s orbit and the solar cycle cause global warming”. While volcanic activity, changes in Earth’s orbit and the solar cycle can (and do) produce changes in climate, the recent trend of these forcings over the last couple of decades is probably towards net cooling. Foster & Rahmstorf (2011) Global temperature evolution 1979–2010. ERL Alexis Berg Research Associate, Harvard University: I find this statement a little weak. As mentioned above, natural factors would not lead to global warming over recent decades. Saying “a number of scientific studies” is a little bit of an understatement: it’s really almost all of the literature on the topic… The IPCC statement in the Summary: for Policy Makers: “It is extremely likely that more than half of the observed increase in global average surface temperature from 1951 to 2010 was caused by the anthropogenic increase in greenhouse gas concentrations and other anthropogenic forcings together. The best estimate of the human-induced contribution to warming is similar to the observed warming over this period. {10.3}”“Another determining factor has been an increase in changed uses of the soil, principally deforestation for agricultural purposes.” Andy Pitman Director of the ARC Centre of Excellence for Climate System Science, The University of New South Wales: This statement is correct. Deforestation leads to the emissions of greenhouse gases, a reduced absorption of gases and a range of other problems that adds to the problem of burning fossil fuels. Jean-François Exbrayat Post-doctoral Research Fellow, The University of Edinburgh: Deforestation is principally the result of the agricultural expansion, for example soy bean and beef production in Brazil (1). The conversion of forests to other types of land use leads to a release of greenhouse gases. Tropical deforestation alone emits around 0.57-1.22 Pg C y-1 (2) globally, or 7-14% of the total anthropogenic emissions. The large uncertainty is due to the complex interactions of multiple mechanisms that occur at different time scales such as instantaneous burning, and slower decay of slash residues (3). However, removing trees limits the capacity of the land surface to absorb atmospheric carbon dioxide and thereby reduces the ability of terrestrial ecosystems to act as long-term carbon stores. (1) Nepstad et al. Science (2014) 344, 1118-1123, doi: 10.1126/science.1248525 (2) Harris et al. Science (2012) 336, 1573-1576, doi: 10.1126/science.1217962 (3) Ramankutty et al. Global Change Biology (2007) 13, 51–66, doi: 10.1111/j.1365-2486.2006.01272.x“Concentrated in the atmosphere, these gases do not allow the warmth of the sun’s rays reflected by the earth to be dispersed in space.” Alexis Berg Research Associate, Harvard University: This is really poorly phrased. If by “warmth of the sun’s rays reflected by the earth” one means something like “infrared radiation emitted by the earth when heated by the sun”, then okay – but that’s a stretch. As it is it makes it sound as if greenhouse gases trap reflected solar radiation… Andy Pitman Director of the ARC Centre of Excellence for Climate System Science, The University of New South Wales: This statement is simply careless – sun’s rays reflected pass back out – its the suns rays absorbed and then re-emitted that get trapped. Its a basic error that should not exist. “The melting in the polar ice caps and in high altitude plains can lead to the dangerous release of methane gas” Alexis Berg Research Associate, Harvard University: This is a bit confused, it seems. While melting ice caps (Greenland, Antarctica) and glaciers will lead to sea-level rise, I am unaware of the fact that it would lead to methane release. On the other hand, the “decomposition of frozen organic material” in, e.g., melting frozen soils of high latitudes (permafrost), could lead to carbon dioxide or methane release (depending on the hydrological conditions associated with this melting, i.e. aerobic or anaerobic).“Things are made worse by the loss of tropical forests which would otherwise help to mitigate climate change.” Jean-François Exbrayat Post-doctoral Research Fellow, The University of Edinburgh: Tropical deforestation contributes to climate change through the emission of greenhouse gases (see my above comment). Although regrowth and reforestation may partially offset these emissions, deforested areas will remain a long-term net source of greenhouse gases (1) unless complete regrowth is allowed. (1) Exbrayat and Williams. Geophysical Research Letters (2015) 42, 2968–2976, doi: 10.1002/2015GL063497 “Carbon dioxide pollution increases the acidification of the oceans and compromises the marine food chain.” Mark Eakin Scientist, Coordinator of NOAA’s Coral Reef Watch, National Oceanic and Atmospheric Administration: The combination of warming and acidification of the ocean is having tremendous consequences on organisms, ecosystems, ecosystem services, and human societies. A recent summary of impacts of ocean acidification can be found in Turley and Gattuso 2012 A recent review of the combined impacts of ocean warming and acidification on ocean chemistry and physics can be found in Howes et al. 2015 A new review of the combined impacts of ocean warming and acidification on ocean chemistry, physics, ecosystems, and dependent human societies coming out shortly: Gattuso J.-P., et al., in press. Contrasting futures for ocean and society from different anthropogenic CO2 emissions scenarios. Science.“However, many of these symptoms indicate that such effects will continue to worsen if we continue with current models of production and consumption.” Alexis Berg Research Associate, Harvard University: Not only will global warming impacts worsen in the future, but it is worth underscoring that global impacts will likely not scale with global mean temperature change, i.e., the impacts of a 4 deg.C warming will not simply be twice as severe as those of a 2C warming.“Each year sees the disappearance of thousands of plant and animal species which we will never know, which our children will never see, because they have been lost for ever.” Dasvinder Kambo, PhD Candidate, Queen’s University Researchers compared current extinction rates to a conservative background estimation of 2 mammalian extinctions /10,000 species /100 years. Our current rates are 114 times higher than the background rate – highest that it has been since previous large extinction events. “Many of the world’s coral reefs are already barren or in a state of constant decline.” Mark Eakin Scientist, Coordinator of NOAA’s Coral Reef Watch, National Oceanic and Atmospheric Administration: Coral reef decline has been well-documented and is accelerating due to the combination of local impacts and the global impacts of ocean warming and acidification due to anthropogenic increases in greenhouse gases. Pandolfi et al. (2003)Global Trajectories of the Long-Term Decline of Coral Reef Ecosystems. Science Knowlton (2001)The future of coral reefs. PNAS Hughes et al. (2003)Climate Change, Human Impacts, and the Resilience of Coral Reefs. Science“It is aggravated by the rise in temperature of the oceans.”Mark Eakin Scientist, Coordinator of NOAA’s Coral Reef Watch, National Oceanic and Atmospheric Administration: We may have reached the point now where climate change has eclipsed the local impacts mentioned in the previous sentence as the greatest, most pervasive threat to coral reefs. See links above."
https://science.feedback.org/review/mashable-andrew-freedman-vanuatu-cyclone-pam-climate-change/,1.5,"Mashable, by Andrew Freedman, on 2015-03-16.",,"""Vanuatu's president makes a leap in tying Cyclone Pam to climate change""",,,,,"The main reason for the positive evaluation is that the author successfully places Cyclone Pam within the larger context of climate change and its’ effect on tropical cyclones, and does so by effectively calling on several scientists with expertise in this field.See all the scientists’ annotations in contextGUEST COMMENTS: Brian Soden, Professor at the University of Miami All of the scientists quoted in that article are reputable, well-respected experts on the subject. The extent to which there’s a diversity of expert opinions expressed in that article concerning the connection between Pam and anthropogenic global warming accurately reflects the degree of scientific uncertainty on the matter and the various ways in which climate change can influence tropical cyclones. For example, sea level has undoubtedly risen due to anthropogenic activities and this certainly increases the storm surge. Likewise, higher moisture contents in the atmosphere lead to higher rainfall amounts in tropical cyclones. The impact of anthropogenic climate change on TC intensity is less clear, and this is reflected in the comments of those quoted. Greg Holland, Willis Senior Scientist and Leader of Regional Climate Section, National Center for Atmospheric ResearchA growing body of published evidence is pointing towards there being substantially more intense tropical cyclones as a result of climate change. And this is not just in the future. Recent studies by us have indicated a substantial increase in the proportion of Category 4 and 5 cyclones both globally and in individual regions that is strongly related to the global surface temperature increases that have already occurred. For the western South Pacific the proportion of Cat 4-5 cyclones has more than doubled in the last 30 years[1]. Thus, the chances of a Pam occurring have increased substantially because of climate change.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Jim Kossin Research Scientist, NOAA's Center for Weather and Climate: An insightful and timely article. There are some statements quoted that are not easily supported and may be overstating the direct impacts of climate change on Cyclone Pam, but the overall message is reasonable. Dan Chavas Assistant Professor, Purdue University: Overall it’s a nice, well-written article that hits most of the key points regarding the complex question of how global warming may affect tropical cyclones. The main issue is with the comments quoted from one of the “experts”, Kevin Trenberth, that are misleading. Emmanuel Vincent Founder & Executive Director, Science Feedback: Even though one may ask whether a single storm is caused by or linked to climate change, this is not a question that science can confidently answer (Vice News has an insightful article on this). What can be more confidently stated is that the impacts associated with Tropical Cyclones (notably coastal surge and floods from cyclonic rainfall) are very likely increasing due to anthropogenic climate change. Hamish Ramsay Lecturer, Monash University: The interannual (El Niño) and intraseasonal (Madden-Julian Oscillation) variability present in the South Pacific at the time of Pam likely contributed to its extreme intensity. It is important that we understand the influence of these internal modes on tropical cyclone intensity within the broader context of a long-term warming trend in the Pacific. References: [1] Holland, G.J. and C. Bruyere, 2014: Recent Intense Hurricane Response to Global Climate Change. Clim. Dyn., 42, 617-627. DOI: 10.1007/s00382-013-1713-0. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time."
https://science.feedback.org/review/wall-street-journal-bjorn-lomborg-alarming-thing-climate-alarmism/,-1.6,"The Wall Street Journal, by Bjorn Lomborg, on 2015-02-01.",,"""The Alarming Thing About Climate Alarmism""",,,,,"The main reason for this negative evaluation is that the author practices cherry-picking: he is selecting limited evidence to support his thesis that “much of the data about climate change are…encouraging”. The evidence provided is insufficient: several examples are either inaccurate or only speak about one aspect of the problem, ignoring much of the published literature on the subject. See all the scientists’ annotations in context GUEST COMMENTS: Gary W. Yohe[1], Huffington Foundation Professor of Economics and Environmental Studies at Wesleyan University Bjorn Lomborg’s op-ed refers to the recent plateau in global mean temperature, but he ignores that the last fifteen years have been very warm; most of the warmest years on record occurred in the past 15. This is a very old argument, that “cherry-picks” data without providing historical context. I am “not a climate scientist, but I know many very good scientists”, so I will not speak more to the science behind that. I will, though, speak to the detected and attributed examples of the observed and anticipated increases in the frequency and intensity of extreme weather events, and the message that Bjorn sends for those whose job is to protect people and natural systems. These events are the fingerprints of the manifestation of a changing climate that has been reported for decades. It is possible to pick one, like droughts, where attribution is difficult because we have so little data. Or others, like hurricanes, where alternative explanations need some more work. It is, though, irresponsible to ignore the preponderance of evidence on floods, extreme precipitation events (and if it is winter, these are snow storms), wildfires, etc. These were anticipated to occur as the climate changes. They have occurred around the world (U.S., Russia, Indonesia, Japan, Argentina, etc..), and they are getting worse and more frequent[2]. Bjorn does speak to impacts on humans with his natural disaster discussion, but he ignores the value of adaptations that communities have undertaken over the past decade or so to reduce risk –successful adaptations based on local social, political and economic context that allow people to survive. Ignoring these activities allows Bjorn to suggest that the climate problem is minimal. That is to say, the reductions in deaths that he reports can be attributed largely to reactions undertaken by communities and societies because they had recognized the “dark tails” of what the future might hold[3]. The message of this opinion piece, if believed, would eliminate the value of responses based on risk –and cost lives and billions of dollars in damage[4] that will then be attributed to a gross misinterpretation of the recent history. Bjorn is a fan of cost-benefit analysis with high discount rates and a single metric, and it is from that perspective that he derives his repetition of the same message. The world has moved on, and the WSJ should know better. Their readers understand risk management; why do not the editors insist that their opinion writers do the same? REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Kyle Armour Assistant Professor, University of Washington: The article contains numerous scientific errors, does not provide references for some of its key claims, and ignores much of the published literature on the subjects discussed. It appears that many details have been cherry-picked or misconstrued in service of making a political point. Alexis Berg Research Associate, Harvard University: The author tries to rebut the narrative “that the world’s climate is changing from bad to worse”. In doing so, he erects a straw-man, cherry-picks studies and misrepresents current climate science. Furthermore, the logic that since things are not ‘worst-than-we-thought’, we shouldn’t take action and do the things we would do if things were simply ‘bad’, is lost on me… Emmanuel M Vincent Research Scientist, University of California, Merced: The article is imprecise, for instance, about who the “doomsayers” and the “alarmists” are: since the core of the argumentation is about them, a definition of who they are and what they argue exactly cannot be avoided. It is also vague in its conclusion: “we need balance”, here again what exactly is meant by balance should be made clearer. John Dwyer Postdoctoral research fellow, MIT: Tries and fails to make a convincing case for why humans need to worry about climate change less than they currently do. Britta Voss Postdoctoral Research fellow, U.S. Geological Survey: Although this author appears to have read parts of the IPCC report and carefully selected the facts which support his narrative, he presents information in a very misleading way, and some of his statements (e.g. “despite endless successions of climate summits, carbon emissions continue to rise”) do not support his thesis that action on climate change is alarmist and unnecessary. His conclusion that “climate change is not worse than we thought. Some indicators are worse, but some are better” suggests a false equivalency between the indicators that are “worse” and those that are “better”. Dan Chavas Assistant Professor, Purdue University: The author on multiple occasions presents blatantly inaccurate information and otherwise uses selective information to argue his point, which is highly misleading. References: [1] Gary Yohe is also – Senior member of the IPCC since the 1990’s; – Member of assorted National Academy of Sciences panels including America’s Climate Choices; and – Vice Chair of the National Climate Assessment Development and Advisory Committee (for the United States) [2]Chapter 18 of the WGII IPCC AR5 report on “Detection and Attribution” of Climate Change impacts [3] Adaptation sections in the regional chapters of IPCC AR5 [4] see e.g. theglobalchange.gov report on Global Climate Change Impacts in the United States. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time."