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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^th 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/

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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/

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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/

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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.