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https://science.feedback.org/review/futurism-story-great-barrier-reef-compromised-sensational-headline/

-0.5

Futurism, by Jolene Creighton, June Javelosa, on 2017-04-12.

"Scientists Announce That The Great Barrier Reef is Officially “Terminal”"

This April 2017 story at Futurism describes a statement released by James Cook University’s ARC Centre of Excellence for Coral Reef Studies on bleaching along Australia’s Great Barrier Reef. Bleaching occurs when corals are exposed to excessively warm water. Scientists who reviewed the article found that most of the information is accurate (except for a couple generalizations), but the headline is not supported by the story. The headline seems to indicate that scientists were quoted as saying the the Great Barrier Reef “is ‘terminal’”, but no source used that word.See all the scientists’ annotations in context This is part of a series of reviews of 2017’s most popular climate stories on social media. REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Terry Hughes Professor, ARC Centre of Excellence for Coral Reef Studies, James Cook University: The content is almost all correct, but the attention-grabbing headline is wrong and isn’t supported by the quotes from two scientists or by the rest of the content. Simon Donner Associate Professor, The University of British Columbia: The short article accurately captures the scientific evidence that repeat mass bleaching events will threaten the Great Barrier Reef, and the message of the ARC official statement. In doing so, however, it is forced into some generalizations including i) describing the Great Barrier Reef as a single entity that can “die” (rather than a complex web of ecosystems that will experience widespread degradation) and ii) stating there have been only four instances of mass bleaching (there have been thousands of events across the world over the past three decades, yet only four years where bleaching occurred in all ocean basins). Mark Eakin Scientist, Coordinator of NOAA’s Coral Reef Watch, National Oceanic and Atmospheric Administration: Much of the story is factually correct. However, the declaration of the reef as “terminal” in the title is a very bad start. What could have been a good story is dragged down by the use of terms like “terminal” without attribution, confuses no time for recovery between back-to-back events with no hope for recovery in the future, and uses a quote saying an expert has “given up” from the perspective of insufficient government action on water quality without providing context for how this relates to a story that is focused on global warming and bleaching. Unfortunately, the facts and quotes don’t support the title. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time.

https://science.feedback.org/review/breitbart-california-fires-misleads-omitting-explanation-climates-influence-joel-pollak/

-1.4

Breitbart, by Joel Pollak, on 2017-12-09.

"Jerry Brown Blames Climate Change for California Fires: ‘The New Normal’"

This article in Breitbart criticizes a statement by California Governor Jerry Brown, who said that the recent dangerous fires are “the new normal” for the area. The article correctly lists a number of factors that contribute to wildfires, including weather patterns and the construction of homes in areas at risk of fire. The article represents the contribution of climate change to wildfire trends as unknown, and a matter of debate for climate scientists. Scientists who reviewed the story found this to be misleading. The article fails to explain the ways in which climate change can clearly influence the factors that control wildfires. A number of published studies have found that climate change is an important contributing factor to wildfire behavior in the western United States.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Anthony LeRoy Westerling Associate Professor, University of California, Merced: The article ignores the overwhelming evidence in peer reviewed scientific literature that warmer temperatures and more variable precipitation are exacerbating western US wildfire activity, leading to more large fires, more area burned, changing fire severity, and longer fire seasons. While many other factors interact with climate to influence wildfire, a changing climate is clearly driving an increase in fire risk. The fact that other factors influence wildfire does not imply that climate has no effect on wildfire. Logan Berner Assistant Research Professor, Northern Arizona University: The Breitbart article provides a poorly reasoned and misleading view of how climate change has contributed to recent fires in California and the rest of the western USA. The most informative part of the article is the link that it provides to a piece by Southern California Public Radio, which, unlike the Breitbart article, provides an informative and unbiased look at factors contributing to these recent fires. Stefan Doerr Professor, Swansea University: The article is factually correct with no significant inaccuracies. Indeed no specific wildfire event can be specifically linked to climate change as the main cause. The article correctly states that “climate change could be one of a variety of factors”. It also correctly states that “an important factor […] was that people are building homes in areas that are naturally prone to wildfires, or where naturally dry conditions mean that the kinds of building materials and vegetation [used] are a fire hazard. This, however, is only one of many factors. Climate is not discussed further and it would have been more balanced if the article had also highlighted that climate scientists (i) have shown that the fire season in the southwest USA has lengthened considerably and (ii) generally agree that climate warming increases the probability of the occurrence of large fires in California (as well as many other regions of the world). See for example: Westerling (2016) Increasing western US forest wildfire activity: sensitivity to changes in the timing of spring, Philosophical Transactions of the Royal Society B Doerr and Santin (2016) Global trends in wildfire and its impacts: perceptions versus realities in a changing world,Philosophical Transactions of the Royal Society B Daniel Swain Climate Scientist, University of California, Los Angeles: This article mixes several true statements with a much larger number of demonstrably false assertions, yielding a very misleading piece overall. While it is true that potential links between climate change and the strength/magnitude of Santa Ana winds themselves remain uncertain, links between warming temperatures and drying vegetation (and therefore wildfire risk) have been extensively demonstrated. Autumn 2017 was the warmest and second driest such period on record in coastal Southern California—which has yielded explosive fire conditions that both the National Weather Service and state/local fire agencies have confirmed are the most severe on record for this time of year. Recent studies suggest that further warming and vegetation drying due to climate change will likely increase the amount of area burned by wildfire in southwestern California, even absent changes in the strength of Santa Ana winds. An even clearer link already exists between warming temperatures and increasing wildfire risk more broadly across the American West. Ben Poulter Research Scientist, NASA: One only has to read the links in the article to understand that climate change is the underlying driver of the unusually intense 2017 winter fires that are impacting both the people and places of Southern California. Wildfires result from complex interactions between ignitions, fuel availability, and weather, and after accounting for the role of people and management, climate change has been shown to affect and exacerbate all three. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time.

https://science.feedback.org/review/daily-caller-uncritically-reports-misleading-satellite-temperature-study-michael-bastasch/

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The Daily Caller, by Michael Bastasch, on 2017-11-29.

"STUDY: Satellites Show No Acceleration In Global Warming For 23 Years"

This article in The Daily Caller describes a recent study published on the University of Alabama at Huntsville satellite temperature dataset. The study claims that, after removing the cooling influence of two large volcanic eruptions in 1982 and 1991, the rate of warming is slower than simulated by climate models. While The Daily Caller story accurately describes the study, it fails to include comments from other scientists in the field or to provide necessary context for readers, as the scientists who reviewed the story explained. For example, the study fails to account for more recent volcanic activity, and does not support its conclusion that climate models are overly sensitive to CO2. In addition, the story’s headline emphasizes that the study shows “no acceleration in global warming for 23 years” and this is presented as a challenge to model simulations. This is misleading, as no acceleration of the warming rate is expected to be seen in such a short timeframe.See all the scientists’ annotations in context This is part of a series of reviews of 2017’s most popular climate stories on social media.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Alexis Berg Research Associate, Harvard University: This article reports on a new study by Christy and McNider that, in my view, contains little new regarding atmospheric temperature trends and seems to simply assert that model-observation discrepancies are due to model errors. Also, it seems the absence of accelerating warming trends is meant to go against prevailing climate science, but I find that to be a strawman argument. In that sense the article is misleading—however, to its credit, it does report on other published results that contradict this recent study, but it fails to provide further context or to make any effort to compare/reconcile the validity of these different studies. Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: The article includes many points made in the original study, but leaves out or de-emphasizes issues that are important to the interpretation of the results. Other factors contribute to model-observational differences in atmospheric warming, but the presentation makes it seem like the difference is largely a result of climate model sensitivity errors. Francois-Marie Breon Senior Scientist, Commissariat à l'Energie Atomique: The general public article provides a fairly accurate summary of the John Christy paper. It may lack some information about the general context, and could have emphasized some of the uncertainties in the satellite data and the fact that the temperature analysis refers to rather high atmospheric levels rather than the low levels where humans live. I also note that, a few years back, the skeptics said that the warming had “stopped” whereas they now say that there is “no acceleration”. This is a nice progress towards the truth. Victor Venema Scientist, University of Bonn, Germany: The article contains some inaccuracies, but the main problem is that it depends on only one source, which the article admits is “contentious”. The authors have a long tradition of overconfidence in their data, their dataset has often needed large adjustments and has a large structural uncertainty and the study was published in a low-level journal. Even without these red flags, it is a good tradition in science reporting to ask experts in the field for their assessment of the study and to provide context, which is completely missing. Bad journalism. Carl Mears Senior Research Scientist, Remote Sensing Systems (RSS): The article does an adequate job of describing the Christy and McNider paper, but leaves out discussion of several assumptions, caveats, and alternative explanations in the original paper. In particular, both the article and the original paper ignore the contribution of small but important volcanic eruptions in the 21st century that have been shown to exhibit a cooling influence on tropospheric temperatures after 2000. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Featured Annotations: The statements quoted below are from the article; comments and replies are from the reviewers. “STUDY: Satellites Show No Acceleration In Global Warming For 23 Years” Carl Mears Senior Research Scientist, Remote Sensing Systems (RSS): The article leaves out several assumptions, caveats, and alternative explanations, some of which are described in the original paper. 1. Both the article and the original paper ignore the effects of smaller but important eruptions in the 21st century that cause a cooling effects that is not included in the model forcings. These have been shown to have a significant effect on the post-2000 trends1,2. The original paper brushes these later eruptions aside without discussing why their results might differ from the earlier Santer et al. results. By then fitting to a model that includes only the earlier eruptions, a decrease in overall warming is guaranteed in their analysis. 2. In the original paper, the authors rightly discuss the possibility that more heat has been sequestered into the ocean in “real life” than is simulated by the models. This is likely the case because of the increase in oceanic windspeed (and thus ocean mixing) in the tropics over the last few decades that is not generally present in the model results. In the article, only the sensitivity to carbon dioxide is discussed, supported by a quote from Dr. Christy. Blaming any model/measurement discrepancy on one possible cause, CO2 sensitivity, that has a large effect on the multidecadal time scale, while ignoring other possible causes, such as smaller volcanoes or internal variability) that may average out on the long term is “cherry picking”. This is done in the article, and to a smaller degree in the original paper. 3. The original paper make an admittedly bold assumption (as noted in the paper) that internal variability can be ignored while calculating transient sensitivity to increasing carbon dioxide. The leads to less uncertainty in the derived transient sensitivity results than can likely be justified. No discussion of this assumption appears in the article. 4. Both the article and the original paper fail to place the new results in context of other diagnostics of global warming. These include surface temperature (which is likely more precisely measured and certainly has a longer measurement record) and ocean heat content (which is likely where at least a portion of the missing heat has gone). 1- Santer et al (2014) Volcanic contribution to decadal changes in tropospheric temperature, Nature Geoscience 2- Santer et al (2015) Observed multivariable signals of late 20th and early 21st century volcanic activity, Geophysical Research Letters Victor Venema Scientist, University of Bonn, Germany: The study was actually about satellite estimates of the upper air temperature for the much longer period January 1979 – June 2017. It is possible to see an acceleration of the warming over the last century. In the graph below showing three well-known temperature change estimates based on the surface air temperature observations the warming is clearly smaller around 1900 than it is around 2000. In other words the warming has accelerated. Source: IPCC For a period of a few decades one does not expect to be able to see an acceleration, especially in the even more noisy upper air temperature estimates. “Global warming has not accelerated temperature rise in the bulk atmosphere in more than two decades” Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: This is not a particularly new result. It has long been known that warming has not accelerated in the observations in the last decade. Although this is well-documented in the surface record, it has also been noted in the satellite record as well. Foster and Rahmstorf (2011) Global temperature evolution 1979 – 2010, Environmental Research Letters Gleisner et al (2016) Recent global warming hiatus dominated by low-latitude temperature trends in surface and troposphere data, Geophysical Research Letters Medhaug et al (2017) Reconciling controversies about the ‘global warming hiatus’, Nature Santer et al (2017) Causes of differences in model and satellite tropospheric warming rates, Nature Geoscience Alexis Berg Research Associate, Harvard University: This is not a new finding. As the article itself mentions, this has been shown in previous studies. Also, this (and the title) makes it sound as though the expectation was too find accelerating trends in atmospheric temperatures (and thus that the “alarmists” are wrong), but I don’t believe this is the case over a relatively short time-span such as the one in this study (30-40 yrs). “We indicated 23 years ago — in our 1994 Nature article — that climate models had the atmosphere’s sensitivity to CO2 much too high,” Christy said in a statement. “This recent paper bolsters that conclusion.” Victor Venema Scientist, University of Bonn, Germany: This 23 years is likely where the mistake in the title comes from. Although the data in this Christy and McNider article from 1994 turned out to have major errors, for example not taking into account that the satellites drift, which caused the underestimation of the warming, it started the tradition of Christy and McNider being overconfident about the reliability of their data (“perhaps the best measurements of the Earth’s air temperature in terms of its global coverage and precision.”). And the tradition of immediately blaming climate models, ignoring many other independent lines of evidence on warming and climate sensitivity, when there can be many other reasons for the difference between their data and climate models. In this 1994 paper, Christy and McNider’s data showed almost no warming. In that respect one could say that 23 years of removing errors from the satellite temperature data has accelerated upper air warming. Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: One curious aspect of this statement is that the trend in over the first 15 years (1979 – 1993) is seemingly taken from a much older version of the UAH satellite lower tropospheric temperature dataset. This dataset has since been improved as inhomogeneities have been discovered and corrected, including satellite orbital decay, an error in the diurnal correction, and a miscalibration of the NOAA-9 satellite. Each of these issues would have spuriously reduced the trend in the UAH dataset—presumably if this specific result were revisited models and satellites would agree much better over 1979 – 1993. Wentz and Schabel (1998) Effects of orbital decay on satellite-derived lower tropospheric temperature trends, Nature Mears and Wentz (2005) The Effect of Diurnal Correction on Satellite-Derived Lower Tropospheric Temperature, Science Po-Chedley and Fu (2012) A Bias in the Midtropospheric Channel Warm Target Factor on the NOAA-9 Microwave Sounding Unit, Journal of Atmospheric and Oceanic Technology Spencer et al (2017) UAH Version 6 Global Satellite Temperature Products: Methodology and Results, Asia-Pacific Journal of Atmospheric Sciences “showed virtually no change in the rate of warming since the early 1990s.” Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: The periods compared by the authors are somewhat arbitrary (1979 – 1993 and 1979 – 2017) since they are comparing their new result with their older study (in 1994). This makes it a little difficult to compare with other studies on this topic, though, again, this result is not necessarily surprising. “Models are too sensitive to increases in carbon dioxide concentrations in the atmosphere, he said.” Victor Venema Scientist, University of Bonn, Germany: He said without providing evidence for this claim. There are many independent lines of evidence on the sensitivity of the global temperature to changes in carbon dioxide concentrations. From basic physics, a large number of different period with climatic changes in the deep past and the cooling observed for volcano eruptions. Source: IPCC Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: While others have documented differences in the rate of warming between models and observations, this study is different in that the authors suggest that these differences are because models are too sensitive to increases in atmospheric carbon dioxide. Several studies disagree with this assessment in both the surface and atmospheric record. Other factors contribute to this apparent discrepancy (and some are noted in the original study). These include the potential for observational biases, errors in external forcing prescribed to the models, and real world multidecadal climate variability. So the attribution of model-observational differences predominantly to models is not supported. Richardson et al (2016) Reconciled climate response estimates from climate models and the energy budget of Earth, Nature Climate Change Santer et al (2017): Causes of differences in model and satellite tropospheric warming rates, Nature Geoscience Alexis Berg Research Associate, Harvard University: This claim is not substantiated by the study. There are several hypotheses to explain why model trends and observations do not agree—internal variability, errors in forcings, model error. Mr. Christy favors the last one, but, as far as I can tell, his study makes no effort to analyse the plausibility of different causes (in fact, it seems they explicitly assume that internal variability and forcing error are not a cause). The other study cited in this piece, Ben Santer’s paper, goes much further and actually tries to evaluate the plausibility of each hypothesis -and, as the article mentions, comes to different conclusions. Note also that surface warming in models is in agreement with observations. The question is then why atmospheric warming seems to not be—the models appear to run a little warm there over the last two decades. “climate models predict too much warming in the troposphere” Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: One issue with such comparisons is that the observational record of atmospheric warming is quite uncertain as evidenced by the large trend differences between different groups that create satellite temperature datasets and even between versions of each group’s datasets. Mears et al (2011) Assessing the uncertainty in estimates of atmospheric temperature changes from MSU and AMSU using a Monte-Carlo estimation technique, Journal of Geophysical Research “While many scientists have acknowledged the mismatch between model predictions and actual temperature observations, few have really challenged the validity of the models themselves.” Alexis Berg Research Associate, Harvard University: A better way to put it would be that, given the data, few have come to the conclusion at this point that models are fundamentally flawed. “A recent study led by Lawrence Livermore National Laboratory climate scientist Ben Santer found that while the models ran hot, the ‘overestimation’ was ‘partly due to systematic deficiencies in some of the post-2000 external forcings used in the model simulations.’” Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: This is right—models have the wrong “external forcings” (such as volcanic forcing), which is likely an important factor in model-observational differences. It is also possible that errors in removing volcanic forcing and natural variability could also affect model-observational comparisons. Solomon et al (2011) The Persistently Variable “Background” Stratospheric Aerosol Layer and Global Climate Change, Science Santer et al (2014) Volcanic contribution to decadal changes in tropospheric temperature, Nature Geoscience “While volcanic eruptions are natural events, it was the timing of these that had such a noticeable effect on the trend” Victor Venema Scientist, University of Bonn, Germany: That is one of the disadvantages of using such a short dataset. For the more reliable station observations of surface air temperature observations go back in the 19th century making the contribution of (individual) volcanoes a lot smaller. Source: Global Warming Index “removing the climate effects of volcanic eruptions early on in the satellite temperature record” Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: Note that although there is nothing wrong with attempting to remove these effects from the temperature time series, it can be quite uncertain and subject to methodology, especially over short timescales. As noted in the research paper, multidecadal variability may also effect the results. Several studies have noted that multidecadal variations in the rate of ocean heat uptake have affected observed warming rates. Santer et al (2001) Accounting for the effects of volcanoes and ENSO in comparisons of modeled and observed temperature trends, Journal of Geophysical Research Chen and Tung (2014) Varying planetary heat sink led to global-warming slowdown and acceleration, Science “‘Those eruptions happened relatively early in our study period, which pushed down temperatures in the first part of the dataset, which caused the overall record to show an exaggerated warming trend,’ Christy said. ‘While volcanic eruptions are natural events, it was the timing of these that had such a noticeable effect on the trend. If the same eruptions had happened near the more recent end of the dataset, they could have pushed the overall trend into negative numbers, or a long-term cooling,’ Christy said.” Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: This study does not include the effect of smaller volcanoes late in the record that would have reduced real-world warming. Since these volcanoes were not included in model simulations, the model simulations would also have too much warming, since they did not include accurate representation of the effect of volcanic activity. This would have increased the model-observational discrepancy. Santer et al (2014) Observed multivariable signals of late 20th and early 21st century volcanic activity, Geophysical Research Letters “climate models need to be retooled to better reflect conditions in the actual climate” Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: It’s important to note that climate scientists do work on both understanding model-observational discrepancies and improving models. Another aspect to consider is that observations also have biases that can affect such comparisons. “policies based on previous climate model output and predictions might need to be reconsidered” Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: This study alone does not support this kind of broad statement, especially given that there are already several studies that disagree with the authors results.

https://science.feedback.org/review/prof-john-christy-incorrectly-claims-to-show-climate-models-are-too-sensitive-to-carbon-dioxide/

Incorrect

The Daily Caller, John Christy, 2017-11-29

the real atmosphere is less sensitive to CO2 than what has been forecast by climate models

Inadequate support: Prof. Christy's study does not provide the evidence to support this conclusion, which contradicts many other published studies.

There are many reasons why a climate model projection may not perfectly match observations of some aspect of Earth's climate over a given time period, including short-term variability, differences between real-world and simulated emissions, and even measurement errors. Prof. Christy asserts that models are too sensitive to CO2 but provides no evidence to support that claim. Other research has concluded that Prof. Christy's assertion is incorrect.

From our observations we calculated that value as 1.1 C (almost 2° Fahrenheit), while climate models estimate that value as 2.3 C (about 4.1° F). Again, this indicates the real atmosphere is less sensitive to CO2 than what has been forecast by climate models.

Victor Venema Scientist, University of Bonn, Germany: He said without providing evidence for this claim. There are many independent lines of evidence on the sensitivity of the global temperature to changes in carbon dioxide concentrations. From basic physics, a large number of different period with climatic changes in the deep past and the cooling observed for volcano eruptions. Source: IPCC Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: While others have documented differences in the rate of warming between models and observations, this study is different in that the authors suggest that these differences are because models are too sensitive to increases in atmospheric carbon dioxide. Several studies disagree with this assessment in both the surface and atmospheric record. Other factors contribute to this apparent discrepancy (and some are noted in the original study). These include the potential for observational biases, errors in external forcing prescribed to the models, and real world multidecadal climate variability. So the attribution of model-observational differences predominantly to models is not supported. Richardson et al (2016) Reconciled climate response estimates from climate models and the energy budget of Earth, Nature Climate Change Santer et al (2017): Causes of differences in model and satellite tropospheric warming rates, Nature Geoscience Alexis Berg Research Associate, Harvard University: This claim is not substantiated by the study. There are several hypotheses to explain why model trends and observations do not agree—internal variability, errors in forcings, model error. Mr. Christy favors the last one, but, as far as I can tell, his study makes no effort to analyse the plausibility of different causes (in fact, it seems they explicitly assume that internal variability and forcing error are not a cause). The other study cited in this piece, Ben Santer’s paper*, goes much further and actually tries to evaluate the plausibility of each hypothesis—and, as the article mentions, comes to different conclusions. Note also that surface warming in models is in agreement with observations. The question is then why atmospheric warming seems to not be—the models appear to run a little warm there over the last two decades. Santer et al (2017): Causes of differences in model and satellite tropospheric warming rates, Nature Geoscience Reto Knutti Professor, ETH Zürich: [This comment is taken from an evaluation of a similar statement.] Statements that climate models overestimate the warming in response to CO2are incorrect; they are based on either too short time periods that are dominated by natural variability, by the comparison of models with datasets that do not have global coverage, by comparing to models that were run many years ago with emissions and forcings that differed from what actually happened, by the use of oversimplified energy balance models1, or a combination of these. Recent studies have shown that once the changes in climate feedbacks over time2, datasets with full coverage3,and all forcings are considered, the agreement between predicted and observed warming is excellent, even over the recent hiatus period4. It is remarkable that even projections made decades ago with climate models that were much simpler (and were running on computers that were likely slower than a mobile phone today) were quite accurate5,6,7. 1- Knutti and Rugenstein (2015) Feedbacks, climate sensitivity and the limits of linear models, Philosophical Transactions of the Royal Society A 2- Armour (2017) Energy budget constraints on climate sensitivity in light of inconstant climate feedbacks, Nature Climate Change 3- Richardson et al (2016) Reconciled climate response estimates from climate models and the energy budget of Earth, Nature Climate Change 4- Medhaug et al (2017) Reconciling controversies about the ‘global warming hiatus’, Nature 5- Stouffer and Manabe (2017) Assessing temperature pattern projections made in 1989, Nature Climate Change 6- Fischer and Knutti (2016) Observed heavy precipitation increase confirms theory and early models, Nature Climate Change 7- Allen et al (2013) Test of a decadal climate forecast, Nature Geoscience Katrin Meissner Professor, University of New South Wales: [This comment is taken from an evaluation of a similar statement.] Climate Sensitivity has been assessed by the community based on recent observations and proxy data from past climates. Climate models fall within this range of sensitivity. Some recent publications point to an increase in sensitivity with warmer temperatures*. Paleosens Project Members (2013) Making sense of palaeoclimate sensitivity, Nature Meraner et al (2013) Robust increase in equilibrium climate sensitivity under global warming,Geophysical Research Letters Zeebe (2013) Time-dependent climate sensitivity and the legacy of anthropogenic greenhouse gas emissions,Proceedings of the National Academy of Sciences

https://science.feedback.org/review/antarctica-doomsday-glaciers-could-flood-coastal-cities-grist-eric-holthaus/

0.8

Grist, by Eric Holthaus, on 2017-11-21.

"Ice Apocalypse"

This article at Grist by Eric Holthaus examines the risk of greater sea level rise caused by a more rapid loss of glacial ice. It focuses on a process recently added to one ice sheet model (ice cliff instability), which greatly accelerated the simulated loss of Antarctic ice in a warming climate, suggesting that we could see more sea level rise by 2100 than previously projected. Scientists who reviewed the article found that while it accurately described recent research on these processes, it should have provided more accurate context on the timescale of these sea level rise scenarios and the scientific uncertainty about how likely these scenarios are to come to pass.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Twila Moon Research Scientist, University of Colorado, Boulder: The major failure of the article is that it incorrectly presents the scientifically published timeline for worst case sea level rise. This is unfortunate, because the overall information in the article about marine ice-cliff instability potentially causing sea levels to rise much sooner than previously thought is correct and important to communicate, and the quoted scientists’ statements are accurate. Henning Åkesson Postdoctoral researcher, Stockholm University and Bolin Centre for Climate Research: The article gives important insight into recent research progress on West Antarctica, the prospects of rapid sea-level rise, and its implications. What is presented is accurate and fairly balanced—though there is by no means a consensus within the glaciological community to whether ice-cliff failure is likely to occur in the future, the possibility is troublesome enough. Alexander Robel Assistant Professor, Georgia Tech: This article does a good job of summarizing some recent work on the potential for a marine ice cliff instability in Antarctica, an idea which is being actively discussed within our community to determine whether it is likely to occur in the future. Since we still do not completely understand all the processes that contribute to ice sheet evolution (including ice cliff breakup), it is difficult to distinguish which specific scenarios are “likely” or “unlikely” beyond saying that: sea level is rising, and it will continue to rise for at least hundreds of years in the future at a rate that is, in part, modulated by human choices. Mauri Pelto Professor of Environmental Science, Associate Dean, Nichols College: The article has a bias, emphasizing the high end scenarios of ice sheet behavior, avoiding scrutiny of model assumptions. The concept of marine ice cliff instability and how unusual it is as a mechanism today on the vast coastline of Antarctica or Greenland is ignored. Jan Lenaerts Assistant Professor, University of Colorado, Boulder: Eric Holthaus provides a dire, but mostly correct, assessment of the processes driving—and risks associated with—a potential rapid disintegration of the West Antarctic ice sheet. The article would be improved in places by providing more context and/or references. Allen Pope Research Associate, National Snow and Ice Data Center, University of Colorado Boulder: This piece does a good job including a range of true experts talking about the frontiers of our understanding of the Antarctic Ice Sheet. While not out of the range of possibility, the future painted (and the associated pessimist/alarmist tendencies) in the article might be a little higher than the research can definitively back up right now. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Annotations: The statements quoted below are from the article; comments and replies are from the reviewers. “finding out how fast these glaciers will collapse is one of the most important scientific questions in the world today” Twila Moon Research Scientist, University of Colorado, Boulder: There are many important science questions, but it is true that understanding the rate of ice loss at Pine Island and Thwaites Glaciers is very important for understanding how quickly future sea level rise will happen. Understanding Thwaites is arguably more important than Pine Island, though they are part of a connect region of ice. A recent peer-reviewed science article that takes a closer look at the question and explains the importance of understanding changes is Scambos et al, 2017*. Scambos et al (2017)How much, how fast?: A science review and outlook for research on the instability of Antarctica’s Thwaites Glacier in the 21st century, Global and Planetary Change “There’s growing evidence that the Pine Island Bay glaciers collapsed rapidly back then, flooding the world’s coastlines — partially the result of something called ‘marine ice-cliff instability.’” Twila Moon Research Scientist, University of Colorado, Boulder: Following earlier theory work by Jeremy Bassis and others, the marine ice-cliff instability term was introduced (as far as I’m aware) in 2015 in Pollard et al, 20151. The two lead authors then continued to investigate the mechanism using computer simulations, publishing a paper in Nature in 20162. The idea of the marine ice-cliff instability is still fairly controversial amongst glaciologists (NOT to be confused with the marine ice sheet instability, which is not controversial and is another reason that West Antarctica is vulnerable to rapid ice loss). A recent paper in Nature3 suggests that there is observational evidence from ancient iceberg tracks, but not all glaciologists are convinced that this new data fully supports the marine ice-cliff instability. Whether the marine ice-cliff instability is something that is likely to occur in Antarctica is still debated amongst scientists. 1- Pollard et al (2015)Potential Antarctic Ice Sheet retreat driven by hydrofracturing and ice cliff failure, Earth and Planetary Science Letters 2- DeConto and Pollard (2016)Contribution of Antarctica to past and future sea-level rise, Nature 3-Wise et al (2017)Evidence of marine ice-cliff instability in Pine Island Bay from iceberg-keel plough marks, Nature Henning Åkesson Postdoctoral researcher, Stockholm University and Bolin Centre for Climate Research: I largely agree. Much of the theoretical framework was established by Bassis and Walker (2012)*. They predicted a “maximum cliff height that increases with water depth”. Bassis and Walker (2012)Upper and lower limits on the stability of calving glaciers from the yield strength envelope of ice, Philosophical Transactions of the Royal Society A “Before human burning of fossil fuels triggered global warming, the continent’s ice was in relative balance” Twila Moon Research Scientist, University of Colorado, Boulder: Yes. Research suggests that the ice sheet was likely near balance up until close to the turn of the 21st century. “All this could play out in a mere 20 to 50 years — much too quickly for humanity to adapt.” Twila Moon Research Scientist, University of Colorado, Boulder: This is a statement that is difficult to justify without a reference to scientific evidence. The current knowledge of time scales involved with rapid ice sheet loss is poor (i.e., solely based on ice sheet models that are crude)—that’s the primary reason why the “How Much How Fast” US-UK program was established. “With marine ice cliff instability, sea-level rise for the next century is potentially much larger than we thought it might be five or 10 years ago” Twila Moon Research Scientist, University of Colorado, Boulder: That is true. For a recent look at how our ideas of likely future sea level rise have changed, this is a useful short piece from Science: How high will the seas rise? If marine ice-cliff instability is confirmed as a likely or expected method of Antarctic ice loss then ice loss can occur more quickly than previously thought. Richard Alley Professor, PennState University: The basic idea is I believe correct—if Thwaites Glacier in West Antarctica in the future begins to behave the way Greenland’s ice sheet is now behaving at Jakobshavn, Helheim and some other outlets, the resulting future sea level rise is likely to be notably higher and faster than currently projected by the IPCC. Iceberg calving from non-floating (tidewater) fronts is a widespread and well-known process (passengers on cruise ships to Alaska have been observing it routinely, for example), and the rate of calving is generally accepted to increase in deeper water and to be favored by reduced friction from the sides, for robust physical reasons. The Greenland outlets are in ~1 km deep fjords that are only a few km wide; furthermore, retreat out of these relatively narrow and short fjords would not greatly raise global sea level (most of Greenland’s ice rests on bedrock that is near or above sea level). Retreat of Thwaites Glacier could reach much deeper water with a much wider calving front, and beyond some threshold of retreat is generally modeled as triggering the full deglaciation of the marine basins with ~3 meters of globally averaged sea-level rise, because so much of West Antarctica’s ice rests on interconnected deep beds. The DeConto-Pollard numbers (and earlier, the Pollard-DeConto-Alley numbers, so note that I was involved with earlier parts of this research) assumed that if triggered, the retreat in West Antarctica would not be as fast as the fastest rates already observed in Greenland (a maximum retreat rate was set in the model); the notably greater sea-level contribution of West Antarctica in the new modeling arises from the much broader calving front that would be activated. But, the greater depth and width of West Antarctica’s deep marine basins than in Greenland could produce much faster calving than in Greenland. Hence, the DeConto-Pollard simulations are not a worst-case scenario. The uncertainties remain very large, especially regarding the amount of warming to that threshold. But, because tidewater calving is such a widespread process, it is highly likely that warming beyond some threshold will cause tidewater processes to occur in West Antarctica, consistent with the paleo-observations in deglaciated marine areas off Pine Island Bay. Current physical understanding then leads to the expectation of quite rapid sea-level rise. Much work remains to be done to narrow the uncertainties, including analyses of the “mélange” of broken-up icebergs mentioned by Ted Scambos—but note that such a mélange is present in the narrow fjord of Jakobshavn, providing a backstress that has still allowed the rapid retreat observed there. I believe DeConto and Pollard have taken a well-justified path in estimating the warming threshold, but much additional work can be done. Many other models that project smaller future sea-level rise from West Antarctica also lack the transition to tidewater calving. If warming becomes large enough to trigger tidewater processes in West Antarctica (or East Antarctica), then models lacking those processes are not useful for providing either most-likely or worst-case scenarios for sea-level rise. “‘Antarctic model raises prospect of unstoppable ice collapse,’ read the headline in the scientific journal Nature, a publication not known for hyperbole.” Jan Lenaerts Assistant Professor, University of Colorado, Boulder: Good to mention that the same journal published another set of Antarctic sea level rise projections one year before (2015) that are far less dire*. Ritz et al (2015)Potential sea-level rise from Antarctic ice-sheet instability constrained by observations, Nature “Instead of a three-foot increase in ocean levels by the end of the century, six feet was more likely, according to DeConto and Pollard’s findings. But if carbon emissions continue to track on something resembling a worst-case scenario, the full 11 feet of ice locked in West Antarctica might be freed up, their study showed.” Twila Moon Research Scientist, University of Colorado, Boulder: This timeline represented here is not an accurate representation of the paper’s findings. Figure 4(below) in the paper is the most helpful. It shows that 11 feet by 2100 in not expected in the tested worst case. However, the paper also addresses sea level rise past 2100. Under the Intergovernmental Panel on Climate Change Representative Concentration Pathway (RCP) 8.5 (the worst case they discussed), the paper suggests sea level rise from Antarctica alone could be 15.65 +/- 2 m by 2500. These numbers are shown in Figure 5 of the Pollard and DeConto Nature paper. A still deeply disturbing finding. Alexander Robel Assistant Professor, Georgia Tech: The study referenced1 finds that, assuming some different possible scenarios for the speed of ice sheet processes and the IPCC’s highest emissions scenario (RCP 8.5), Antarctica alone can contribute anywhere from 0.5 to 4.5 feet (Figure 5b and d, below) of sea level rise. The DeConto & Pollard study1 does not include the potential for sea level rise from thermal expansion of sea water, melting of mountain glaciers or the Greenland Ice Sheet in it’s projections, but if these are included, the total sea level rise projected for 2100 may be something like 6 feet. If this is the calculation implicit in this statement that “…six feet was more likely, according to DeConto and Pollard’s findings”, than it is perhaps a bit misleading, since DeConto & Pollard is only focused on the contribution from the Antarctic Ice Sheet. As DeConto & Pollard say in their study: “…the rates of ice loss simulated here should not be viewed as actual predictions, but rather as possible envelopes of behaviour”. Determining the “likely” amount of sea level rise in the future is a prediction that is strongly dependent on the assumptions about how ice sheet behave and on what time scales. Based on just DeConto & Pollard’s studies, and the assumptions inherent in their model, one can conclude that it is likely that sea level will rise by more than 11 feet, just from Antarctic melting, over the next several centuries, if humans do not significantly reduce emissions of greenhouse gases (see Figure 5 and S7 of DeConto & Pollard 2016). What the glaciological community as a whole considers “likely” depends on which processes we think are likely to be important contributors of ice sheet collapse, which is a matter that is actively under debate. Since the DeConto & Pollard study is relatively new, there is still an ongoing discussion about how likely it is that the Marine Ice Cliff Instability will actually occur and at what rate will it causes ice to be lost from individual glaciers. Though the article as a whole covers some parts of this debate, these individual statements about likelihood do not necessarily reflect a community consensus. DeConto and Pollard (2016)Contribution of Antarctica to past and future sea-level rise, Nature “it now seems like three feet is possible only under the rosiest of scenarios” Henning Åkesson Postdoctoral researcher, Stockholm University and Bolin Centre for Climate Research: Given DeConto and Pollard’s results, yes, though their model is one out of several models being actively developed to predict future sea-level rise. Alexander Robel Assistant Professor, Georgia Tech: Including the contribution from thermal expansion of seawater, mountain glaciers, and Greenland, three feet is probably a good estimate for the lower bound on the total sea level rise that can be expected from current and past climate change (many studies ask this question, but Pfeffer, 2008* is an oft-cited example). The key phrase here is total sea level rise, which may unfold in the next century or over the next several millennia as ice sheets continue to respond to past climate change for many hundreds to thousands of years. If this phrase refers to three feet of sea level rise from Antarctica by 2100, then it does not accurately represent the findings of DeConto & Pollard (see RCP 2.6 in Figure 5 of that study, above). Pfeffer et al (2008)Kinematic Constraints on Glacier Contributions to 21st-Century Sea-Level Rise, Science “the world’s most vulnerable megacities, like Shanghai, Mumbai, and Ho Chi Minh City, could be wiped off the map” Henning Åkesson Postdoctoral researcher, Stockholm University and Bolin Centre for Climate Research: I think this statement is too dramatic. While rising seas is a very serious challenge for populous coastlines worldwide, we have the possibility to adapt. But of course the ability to adapt will depend on how fast these changes pan out. “Pollard and DeConto are the first to admit that their model is still crude, but its results have pushed the entire scientific community into emergency mode.” Twila Moon Research Scientist, University of Colorado, Boulder: Many people in the glaciology community are working to improve computer models of ice sheet change. I actually think that many scientists already felt that humans should be in “emergency mode”. For reference, consider the “World Scientists’ Warning to Humanity”, first written in 1992 and reprised this year. But I agree that the possibility of marine ice-cliff instability raised another alarm bell. “Scientists used to think that ice sheets could take millennia to respond to changing climates” Twila Moon Research Scientist, University of Colorado, Boulder: This was a common perspective before the era of satellite data that showed rapid changes on ice sheets. “In a new study out last month in the journal Nature, a team of scientists from Cambridge and Sweden point to evidence from thousands of scratches left by ancient icebergs on the ocean floor, indicating that Pine Island’s glaciers shattered in a relatively short amount of time at the end of the last ice age.” Twila Moon Research Scientist, University of Colorado, Boulder: As noted earlier, I think there is still some disagreement on whether these are conclusive results. “But there’s reason to think Thwaites and Pine Island could go even faster than Jakobshavn.” Henning Åkesson Postdoctoral researcher, Stockholm University and Bolin Centre for Climate Research: I don’t think we know this yet, and the author doesn’t really back up this claim. The topography beneath Jakobshavn extends to great depths (more than 1 km) for several tens of kilometres upstream of the current calving front (see this recent study by An et al, 2017*). This type of geometry may allow for rapid retreat without any extra push from a warming climate. Thwaites and Pine Island are completely different beasts—the sheer scale and the sea-level equivalent they contain is what’s troublesome with these two. An et al (2017)Bed elevation of Jakobshavn Isbræ, West Greenland, from high-resolution airborne gravity and other data, Geophysical Research Letters Alexander Robel Assistant Professor, Georgia Tech: Yes, there are reasons to think Thwaites and Pine Island could collapse quickly, the most basic among them being that these glaciers are wider and potentially more slippery at the bed than Jakobshavn. “But recent examples from other regions, like the rapidly collapsing Larsen B ice shelf on the Antarctic Peninsula, show that once ice shelves break apart as a result of warming, their parent glaciers start to flow faster toward the sea, an effect that can weaken the stability of ice further inland, too.” Jan Lenaerts Assistant Professor, University of Colorado, Boulder: Regarding ice shelf stability, it is important to acknowledge (which the author didn’t do here) there are different processes at work on the Antarctic Peninsula, where the Larsen ice shelves reside(d), than on the Amundsen coast (Pine Island and Thwaites ice shelves). The Larsen A and B ice shelves were very thin, and have disintegrated from percolating surface meltwater (hydrofracturing) creating vertical cracks in the ice shelf. Larsen C is thicker and larger, but is also characterised by a relatively warm climate (many melt episodes in summer) and low snowfall (which makes it vulnerable to atmospheric warming). The ice shelves that buttress the Pine Island and Thwaites glaciers are much thicker, annual snowfall rates are very large, and surface melt rates are substantially lower than on the (former) Larsen ice shelves (3-5 times lower). Therefore, it is highly unlikely that surface-based ice shelf instability will occur within the next few decades—instead, these ice shelves would likely thin through contact with warmer ocean waters. “‘If you remove the ice shelf, there’s a potential that not just ice-cliff instabilities will start occurring, but a process called marine ice-sheet instabilities,’ says Matthew Wise, a polar scientist at the University of Cambridge. This signals the possible rapid destabilization of the entire West Antarctic ice sheet in this century.” Twila Moon Research Scientist, University of Colorado, Boulder: Multiple studies have indicated that the marine ice sheet instability is likely already underway in the Pine Island region1,2. There has been no evidence to suggest that the loss of ice from this region will stop. However, that the loss of ice from marine ice sheet instability is underway does NOT mean that the entire West Antarctic Ice Sheet will destabilize this century. There is no evidence for the ice loss to occur that quickly. 1- Joughin et al (2014) Marine Ice Sheet Collapse Potentially Under Way for the Thwaites Glacier Basin, West Antarctica, Science 2- Rignot et al (2014) Widespread, rapid grounding line retreat of Pine Island, Thwaites, Smith, and Kohler glaciers, West Antarctica, from 1992 to 2011, Geophysical Research Letters “What we do now will determine how quickly Pine Island and Thwaites collapse. A fast transition away from fossil fuels in the next few decades could be enough to put off rapid sea-level rise for centuries. That’s a decision worth countless trillions of dollars and millions of lives. ‘The range of outcomes,’ Bassis says, ‘is really going to depend on choices that people make.’” Twila Moon Research Scientist, University of Colorado, Boulder: There is no question that this is correct. The future rate of ice loss (from Antarctica and elsewhere) is linked to the rate of global warming and that is determined primarily by human activity. A useful reference is Clark et al (2016). Clark et al (2016)Consequences of twenty-first century policy for multi-millennial climate and sea-level change, Nature Climate Change Henning Åkesson Postdoctoral researcher, Stockholm University and Bolin Centre for Climate Research: This is an accurate statement. Talking about uncertainty in these scenarios of sea-level rise, I think the biggest of them all is how global emissions will develop over the next years and decades. What we do now will affect the outcome decades and centuries into the future. We do not know what the tipping points are in these systems, or whether we’ve crossed that line already. It is critical to establish whether retreat may become self-sustainable—that is, once we push the ball off the edge, it may keep rolling downhill even if we reverse current emission trends. That possibility is to me enough to dedicate significant funds and personnel on this problem. Jan Lenaerts Assistant Professor, University of Colorado, Boulder: This is strongly supported by the DeConto and Pollard 2016 Nature paper*, which showed that the Antarctic contribution to committed sea level rise can be limited to ~20 cm in a strong climate mitigation scenario (RCP2.6). DeConto and Pollard (2016)Contribution of Antarctica to past and future sea-level rise, Nature Alexander Robel Assistant Professor, Georgia Tech: The speed of glacier evolution and possibly collapse are certainly modulated by the rate of climatic changes at all points during glacier evolution. The question of specifically where glacier collapse is already underway or where it can be avoided by human choices is currently being investigated by many in the glaciological research community.

https://science.feedback.org/review/guardian-sea-level-rise-cities-fails-make-timescale-clear/

0.5

The Guardian, by Ruth Michaelson, Richard Luscombe, Niko Kommenda, Justin McCurry, Josh Holder, Jonathan Watts, Helen Roxburgh, Dom Phillips, on 2017-11-03.

"The three-degree world: the cities that will be drowned by global warming"

This story in The Guardianincludes maps of, and reporting from, five coastal cities that will be affected by continued sea level rise. The story discusses the impact sea level rise will have on those cities, and what they are doing to prepare and adapt. However, scientists who reviewed the story found that it fails to explain one very important thing to readers: nowhere is it explained that the magnitude of sea level rise shown (for a scenario in which the world warms by 3°C) is the amount that would occur after the planet has had centuries to millennia to come into equilibrium with elevated temperatures. Readers are likely to assume that the story’s maps illustrate sea level rise that could occur before the end of the 21st century, but this is not the case.See all the scientists’ annotations in context UPDATE (15 November 2017): The Guardian article has been updated to include some explanation in an expandable box. It states, in part, “How quickly will oceans rise? It could take decades or centuries, but change will be locked in by a 3C temperature rise, which would extensively melt ice caps, shrink glaciers and thermally expand the oceans so many current coastlines and low-lying plains would be under sea level.”REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Chris Roberts Research Scientist, ECMWF/Met Office: The methodology is appropriate, but the time scales involved should have been made clearer. From the original report, “locked in” sea level is defined as “the sustained temperature increase or SLR that will ensue on a time scale of centuries to millennia”. This is not the same as the sea level rise that has already occurred if temperatures reach 3 °C, which is not obvious from the figures or text. Andrew Shepherd Professor, University of Leeds: The Guardian article makes no mention of the timescale over which the “locked-in” sea level rise associated with a 3 °C climate warming would take place. The Climate Central report states that “the sea levels described could possibly, but with low probability, occur sooner than 200 years from now, or be reached as far as 2,000 years in the future”. Most readers would interpret this to mean there is a high probability that the timescale for the associated sea level rise would therefore fall between 200 and 2,000 years. This would have been a useful piece of information for the Guardian article to make clear. I think the Guardian article can be judged as misleading, because the only timescales mentioned are those of the warming and not the consequent sea level rise, and these are not matched. Jeremy Fyke Postdoctoral researcher, Los Alamos National Laboratory: This article provides an excellent visual of an unfortunately very likely general future for humanity, in which sea level rise slowly inundates many coastal cities with accelerating impacts on a vast global population. It is very well presented visually, and does a great job of attempting to link global change (sea level rise) to impacts on individuals and communities—which is practically the whole point of worrying about climate change in the first place. However, one major drawback of this article is that the magnitude and timescale of the sea level rises described in this report are not well explained. This probably leaves readers confused about, for example, what exact level of sea level rise is actually shown in the interactive plots, and over what timescale this could occur. This weakness in turn relates back to the methodology of the single study that underpins this work: Levermann et al, 2013*. In this work, they estimate the final sea level rise that occurs after several thousand years of climate response to greenhouse gas emissions. Unless I’m mistaken, it seems that this magnitude of sea level rise is what is being shown in these figures. (Though this is impossible to verify since no actual sea level rise numbers are printed, I think!) What is shown is not the sea level rise that will occur at year 2100 (as is sort of implied by the presence of figure 1). Thus it is a bit disingenuous to elicit reader reactions to sea level rise plots which represent scenarios that will practically not occur for thousands of years. If we’re talking practical responses to sea level rise in present-day cities, we also need to talk about practically relevant sea level changes (not changes 2,000 years in the future, although these are of profound significance as well). Unfortunately, this article somewhat conflates millennial-scale sea level change with near-term (i.e., decadal to 2100-scale) responses. Regardless, I continue to encourage this type of work by the Guardian to portray complex and critically societally relevant scientific data in a way that is immediately interpretable by the public. Levermann et al (2013) The multimillennial sea-level commitment of global warming, PNAS Jan Lenaerts Assistant Professor, University of Colorado, Boulder: Well-documented and well-referenced article in The Guardian with innovative graphics and a gripping mix of science and personal stories of people living in vulnerable cities. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time.

https://science.feedback.org/review/independent-makes-giant-leap-global-warming-worse-than-thought-single-study-andrew-griffin/

-0.7

The Independent, by Andrew Griffin, on 2017-10-26.

"Climate change might be worse than thought after scientists find major mistake in water temperature readings"

This article in The Independent describes a study examining one type of “proxy” record for past global temperatures the geologic record. The study found a potential problem with temperature estimates for time periods tens of millions of years ago, but this article concludes that the study means current climate change is “far worse than previously calculated”. Scientists who reviewed the article explained that this conclusion is not logically connected to the contents of the study. The article exaggerates the study’s implications for records of past climate—there are multiple types of proxy records that have been used to study those time periods— and invents implications for future warming.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Marcus Badger Lecturer in Earth Sciences, The Open University: The article reports on a paper which suggests there may be complications with ONE method we use to determine past ocean temperature. Notwithstanding possible flaws in the methods of the paper, the article ignores significant evidence from other measurements and observations and tells us nothing directly about the severity of future and present climate change. Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: This article takes the results of an experiment and, fuelled by some irresponsible hyperbole from the authors of the study, extrapolates incorrectly to modern climate change. The tone of the article is overly alarmist and unfounded based on the study in question. Mitch Lyle Professor, Sr. Research, Oregon State University: The article has minor inaccuracies reporting a flawed study. The original study has defects. If all the past records of climate warming via oxygen isotopes were wrong, they would need to be buried to the same depth (or at least to the same temperature) to get the common overprint. Depth of burial varies by a huge amount. The study also fails to acknowledge that oxygen isotopes are only one way used to measure ocean temperature. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Featured Annotations: The statements quoted below are from the article; comments and replies are from the reviewers. “Climate change might be worse than thought after scientists find major mistake in water temperature readings The sea was much colder than previously thought, the study suggests, indicating that climate change is advancing at an unprecedented rate” Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: This title and subtitle are totally misleading. The question of whether or not some (and I stress some because this only affects one proxy, not the others that suggest warm temperatures) temperature estimates were wrong has no bearing at all on the rate of current climate change. Marcus Badger Lecturer in Earth Sciences, The Open University: Even if it were correct, there is no direct link between our understanding based on the method discussed in the paper and our understanding of the severity of future and present climate change. The paper does not find a “major mistake” but suggests there may be complications with ONE method used to reconstruct past ocean temperatures. “The research challenges the ways that researchers have worked out sea temperatures until now, meaning that they may be increasing quicker than previously suggested.” Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: I don’t think there’s a link between alteration of deeply buried sediments in this study (i.e., oxygen isotope measurements from millions of years ago) and current rates of temperature increase (directly measured from satellites and weather stations). It may challenge the way we work out sea temperatures (although as I will note later the paper seriously overstates its case), but this doesn’t change the observed rates of change in the post-industrial era. This is inaccurately presented. Marcus Badger Lecturer in Earth Sciences, The Open University: There is no link between the method the paper studies to construct past temperature changes (oxygen isotopes in foraminifera) and present temperature increase (measured using satellites, direct measurements and other proxies). “If true, that means that the global warming we are currently undergoing is unparallelled within the last 100 million years” Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: The study suggests some periods of time may (according to one proxy) be cooler than originally thought, but this doesn’t change the “rate” of warming seen today. This isn’t anything to do with the study. There are confused messages coming out here about rate of change vs. absolute values. Certainly we are not reaching temperatures today that are warmer than over the last 100 million years, either with or without the results of this study. “and [current global warming is] far worse than we had previously calculated.” Marcus Badger Lecturer in Earth Sciences, The Open University: This does not follow logically from the previous sentences. “But [ocean temperatures 100 million years ago] might in fact have stayed relatively stable” Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: “Relatively” being the operative word here. And in any case, there is evidence of warmer poles from other proxies besides oxygen isotopes—organic biomolecule-based proxies (like TEX86), for example. Quite aside from that, there were lush forests where today there is only ice. The fact that the poles were warmer is not something to be called into question by this one study on one proxy, on one type of foraminifera subjected to very high temperatures in the lab. I don’t suggest that this can’t be operating on oxygen isotopes at some level, but given the wealth of other evidence, I suggest the authors of this study, and subsequently the author of this piece, have gone well overboard with their assessment. “‘If we are right, our study challenges decades of paleoclimate research,” said Anders Meibom, the head of EPFL’s Laboratory for Biological Geochemistry and a professor at the University of Lausanne.” Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: It seems the authors of this paper are not au fait with the decades of work that has been done with other proxies that also show warmth at these times, since they take their observed changes in oxygen isotopes in deeply buried and heated sediments, and extend their results outrageously, discounting hundreds of papers on either shallow, well-preserved samples, or organic temperature proxies, or pollen assemblages, or leaf margin analysis, or clumped isotopes—all of which show that the poles were indeed warmer at this time. Marcus Badger Lecturer in Earth Sciences, The Open University: It only potentially challenges ONE method used to reconstruct past temperatures. Other methods and observations based on biomarkers, pollen, large fossils support a much warmer ocean at this time. “Until now, scientists have calculated the temperature of the ancient seas by looking at foraminifera, the fossils of tiny marine organisms found in the sediment on the ocean floor.” Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: This is only one way that scientists have calculated the temperature of the ocean, and they will continue to do so. “But the new research shows that the amount of oxygen in those shells doesn’t actually remain constant over time.” Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: It’s nothing to do with the amount of Oxygen. It’s CaCO3, so oxygen content is pretty much fixed—it’s the isotopic ratio of the oxygen that is incorporated. Marcus Badger Lecturer in Earth Sciences, The Open University: This is a misunderstanding of the way that oxygen isotopes work. “The new research showed that [oxygen isotopes in foraminifera] can change” Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: There is not enough information here. This research specifically only showed that they could change when heated to 300˚C. By not saying what the circumstances are under which the temperature estimates can be altered, the article throws undue doubt on what is in most settings (despite what the authors of the study seem to be suggesting) pretty robust. “This means that the paleotemperature estimates made up to now are incorrect” Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: This is a huge overstatement. It in fact means that some paleotemperature estimates made up to now may be incorrect. An interesting finding, but being over-stated in the extreme. “The changes in the amount of oxygen in the shells isn’t a reflection of changing temperatures – just a consequence of the fact that the amount of oxygen seen changes over time anyway.” Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: It doesn’t just change over time anyway. Firstly, we are talking about the isotope ratio of oxygen, not the amount. Secondly, the authors show evidence that in some depositional settings this sort of “resetting” of temperatures could occur. By over-simplifying here the author of the article loses and obscures the original study. “To revisit the ocean’s paleotemperatures now, we need to carefully quantify this re-equilibration, which has been overlooked for too long. For that, we have to work on other types of marine organisms so that we clearly understand what took place in the sediment over geological time” Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: Or use other temperature proxies to compare with the oxygen isotope data to see if they are consistent—which is what has been done for years. Marcus Badger Lecturer in Earth Sciences, The Open University: There are already other methods based both on different organisms and different proxy methods which the authors ignore.

https://science.feedback.org/review/commentary-australian-ignores-evidence-misrepresents-research-falsely-claiming-humans-not-responsible-climate-change-ian-plimer/

-2

The Australian, by Ian Plimer, on 2017-10-23.

"Misguided renewable energy policies will ruin nation"

This opinion in The Australian by Ian Plimer repeats a number of false but common claims to support an argument that human activities are not responsible for climate change, and that renewables like wind and solar cannot effectively replace fossil-fuel-burning power plants. The scientists who reviewed this article found that it lacks scientific credibility. They explain that the author either ignores or is unaware of the abundance of scientific research that directly contradicts his claims about the cause of global warming.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Kenneth Gillingham Associate Professor, Yale University: This article is full of scientific inaccuracies and reveals a weak understanding of energy technologies and markets. Peter Neff Assistant Research Professor, University of Minnesota: Yet another in the exhausting heap of opinions choosing not to engage with evidence, while still expecting readers to believe inaccurate and baseless claims. It is baffling why publications such as The Australian wish to promote opinions that are both not well-argued and demonstrably not based on fact. Sara Vicca Postdoctoral research fellow, University of Antwerp: The article is full of incorrect information and flawed, misleading reasoning. Peer Nowack Independent Research Fellow, Imperial College London: An article that either chooses to ignore scientific arguments, or to take them out of context in order to misuse them. Could not find scientifically accurate and well backed-up claims. Aimée Slangen Researcher, Royal Netherlands Institute for Sea Research (NIOZ): This article is misleading and ignores vast bodies of scientific research on climate change. It uses clearly incorrect statements and/or flawed reasoning to argue in favor of the authors’ opinion on climate change and energy policies. Malte Stuecker Postdoctoral research fellow, University of Washington: The article is full of false statements, many of which have been rebutted multiple times. Nathaelle Bouttes Research scientist, CNRS, Laboratoire des Sciences du Climat et de l'Environnement (LSCE): The article is misleading and presents inaccurate arguments that have no scientific support in the literature. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from the article; comments and replies are from the reviewers. 1.Human activities have unambiguously increased the concentration of greenhouse gases in Earth’s atmosphere since the beginning of the Industrial Revolution. Physics predicts that the unavoidable consequence of that increase is the warming we have observed. “Global human emissions are only 3 per cent of total annual emissions.” Sara Vicca Postdoctoral research fellow, University of Antwerp: Global human emissions are indeed only a small percentage of what ecosystems cycle, but the reasoning is completely flawed. Regarding the impact on climate, it is the net emissions that matter, not the amount of carbon that is being cycled over and over. Terrestrial ecosystems take up and re-emit about 12 times more CO2 than humans emit, and oceans cycle about 9 times more CO2 than we emit. BUT! This carbon uptake and release is more or less balanced at the annual scale, and net ecosystem emissions are even negative. Without these ecosystems, atmospheric CO2 concentration would have risen even more as a consequence of fossil fuel burning; the CO2 concentration in the air would already be around 550 ppm (instead of the current ~400 ppm). Hence, it is absolutely misleading to compare amounts of CO2 cycling through the ecosystems with human CO2 emissions in this context. If anything, the CO2 cycling through the ecosystems should be taken as a reason to safeguard them: if we lose these carbon sinks, CO2 in the air will increase no matter what we do. Ana Bastos Group Leader, Max Planck Institute for Biogeochemistry: This is purposely misleading. Others have commented appropriately. The global carbon budget provides an overview of sources and sinks of CO2 since 1880. Source: Global Carbon Project Peer Nowack Independent Research Fellow, Imperial College London: Others have already commented on this in detail. Just to emphasize: the statement is clearly misleading. What matters here is how human emissions drive the net atmospheric CO2 budget (emissions minus uptake) out of balance, which leads to an accumulation of CO2 in the atmosphere. “It has never been shown that human emissions of carbon dioxide drive global warming.” Peer Nowack Independent Research Fellow, Imperial College London: This sentence essentially ignores many thousands of studies that provide evidence to the contrary (i.e., that human CO2 emissions ARE driving global warming) and is therefore factually wrong. IPCC (2013) Climate Change 2013: The Physical Science Basis Wolfgang Cramer Professor, Directeur de Recherche, Mediterranean Institute for Biodiversity and Ecology (IMBE): Virtually all statements in this article have been proven wrong so many times by scientific experts that it is unreasonable to once again show that they are wrong. But I want to focus on the statement “it has never been shown” only. How can one claim that the impact of anthropogenic greenhouse gas emissions has “never been shown that…”? Clearly, for this author, science per se either does not exist or else has no credibility whatsoever. Surely then, scientific research itself cannot exist, there is no geology to find coal resources, no studies “of natural processes such as ocean degassing”, etc. From this, one can only conclude that we actually cannot know anything—not even the things that this author believes to be true. Aimée Slangen Researcher, Royal Netherlands Institute for Sea Research (NIOZ): This is not true. In fact, there is a vast body of work on detection and attribution, which specializes in exactly this: determining the causes of observed changes in climate. This happens in a two-step process. Step 1 (the detection step) looks at whether observed changes can be explained by internal climate variability. If the answer is no, step 2 (the attribution step) determines which factors explain the observed changes. “natural processes such as ocean degassing, volcanoes, natural chemical reactions and exhalation don’t drive global warming.” Peter Neff Assistant Research Professor, University of Minnesota: Here is a great illustration of how these processes don’t drive warming over the observational period: https://www.bloomberg.com/graphics/2015-whats-warming-the-world/ “In the geological past, Earth’s atmosphere had hundreds of times the CO2 content of the modern atmosphere yet there were no carbon dioxide-driven catastrophes. The past shows that climate change is normal, that warmer times and more atmospheric carbon dioxide have driven biodiversity and that cold times kill.” Peer Nowack Independent Research Fellow, Imperial College London: There are many problems with this statement, starting with an entire lack of accuracy. It reads like a series of generic statements that can easily be taken out of context and are entirely irrelevant to the problem at hand. One particularly striking point is the implicitly obvious lack of awareness for timescales. Atmospheric CO2 concentrations are changing at unprecedented rates now, posing a serious threat to biodiversity in rapidly changing ecosystems. Aimée Slangen Researcher, Royal Netherlands Institute for Sea Research (NIOZ): Indeed, climate change is normal, but there are 2 important differences with respect to the geological record: 1) the current rate of increase in CO2 is unprecedented and 2) the current CO2 increase is caused by human emissions. “Ice core drilling shows that 800 years after natural warming, the atmosphere increases in carbon dioxide” Nathaelle Bouttes Research scientist, CNRS, Laboratoire des Sciences du Climat et de l'Environnement (LSCE): Recent work* shows that the temperature and CO2 rise were synchronous within uncertainties: if there was a lag it was less than 400 years, not 800 years as previously thought. Additionally, the temperature increase over the deglaciation cannot be explained solely by orbitally driven insolation changes (modifications of solar energy received by the Earth due to its position). The radiative effect of the CO2 rise amplifies the warming and explains part of the total deglacial warming. Parrenin et al (2013) Synchronous Change of Atmospheric CO2 and Antarctic Temperature During the Last Deglacial Warming, Science “Instrumental temperature measurements over the past 150 years show no correlation between human emissions of CO2 and ­temperature.” Emmanuel Vincent Founder & Executive Director, Science Feedback: Plotting the relationship between global temperature and the logarithm of atmospheric CO2 concentration shows a strong relationship (figure below). This is predicted by physics* since CO2 is a greenhouse gas. Ian Plimer might be confusing CO2 emissions and CO2 concentration in the atmosphere, which is what matters for explaining Earth’s surface temperature. Figure – Global temperature from Berkeley Earth’s dataset versus atmospheric CO2 concentrations. Huang and Shahabadi (2014) Why logarithmic? A note on the dependence of radiative forcing on gas concentration, Journal of Geophysical Research Atmospheres Peter Neff Assistant Research Professor, University of Minnesota: Instrumental temperature measurements over the last 150 years record weather/climate that is influenced by more than ONLY CO2. Natural variation must also be considered, including semi- to multi-decadal processes involving the ocean and atmosphere (e.g. El Niño-Southern Oscillation). “On all timescales it can be shown that there is no correlation between CO2 emissions and global warming.” Peter Neff Assistant Research Professor, University of Minnesota: This is simply false. Ice cores show correlation over ice age cycles (100,000 years). The modern observational record shows correlation that cannot be reproduced without including greenhouse gases (CO2, CH4, N2O). Climate models demonstrate this correlation very well. If you include only natural climate forcing (volcanoes, solar variations, etc.) over the observational period, models UNDERpredict observed temperatures. If you include only greenhouse gas forcing over the observational period, models OVERpredict observed temperatures. If you include natural, greenhouse gas, and other anthropogenic forcings (including cooling effects of coal/soot pollution particulates), models quite accurately match observations. Comparison between global mean surface temperature anomalies (°C) from observations (black) and AOGCM simulations forced with (a) both anthropogenic and natural forcings and (b) natural forcings only. Source: IPCC “The worldwide temperature record has been changed. Cooling trends have been ‘homogenised’ to warming trends. In the corporate world, if a loss is ‘homo­genised’ to a profit, it is fraud.” Peter Neff Assistant Research Professor, University of Minnesota: This point has been refuted ad nauseam. See Zeke Hausfather’s explaination here: https://www.carbonbrief.org/explainer-how-data-adjustments-affect-global-temperature-records Berkeley Earth independently assessed these records. The adjustments, which are necessary over 150-200 years of measurements of varying type and quality, end up reducing the warming trend over the 20th Century. Ana Bastos Group Leader, Max Planck Institute for Biogeochemistry: Every time new data is assimilated, the record is bound to change slightly. I think the author is referring to a discontinuity in the global temperature record around 1945 that was shown to be due to changes in the instruments after WWII*. Since this discontinuity was reported, new temperature products were corrected for instrumentation change. This is not fraud, just good science. Thompson et al (2008) A large discontinuity in the mid-twentieth century in observed global-mean surface temperature, Nature 2.The author makes inaccurate claims about greenhouse gas emissions in Australia and about renewable energy systems. “[South Australia] has the most expensive electricity in the world.” Kenneth Gillingham Associate Professor, Yale University: This is misleading. It is true that prices have rapidly increased, largely due to high natural gas prices from the start-up of gas liquefaction plants. However, there are plenty of other regions within countries (note South Australia is a region within the country of Australia) with just as high or higher electricity prices. How about villages in Alaska? Small islands? This claim is just misleading. “Unless the laws of physics are changed, solar power cannot be made more efficient.” Kenneth Gillingham Associate Professor, Yale University: This is incorrect. Sure, if you use exactly the same technologies we have today there is a barrier to the efficiency of polycrystalline solar panels. But there are many other technologies in the works that can have much higher efficiency. Lew (2016) Research opportunities to advance solar energy utilization, Science “Construction and maintenance of wind and solar facilities ­release far more carbon dioxide than they are meant to save over their working lives and they need to be sup­ported 24/7 by coal-fired generators.” Kenneth Gillingham Associate Professor, Yale University: This is completely incorrect. There are numerous studies contradicting this. For example, see a series of studies by Sally Benson at Stanford University. Frankly, both parts of this claim are absurd. Coal-fired generators are particularly poorly-suited to act as a backup for solar because they generally are very expensive to ramp up and down, so they are used almost everywhere around the world as baseload generators. Natural gas or hydro are much better suited as backup. This sentence belies a lack of understanding of energy technologies and markets. “[Those who signed the Paris Accord] cannot change Earth’s orbit and radiation released from the sun that drive climate” Aimée Slangen Researcher, Royal Netherlands Institute for Sea Research (NIOZ): The problem we are dealing with here is not the radiation released from the sun, but with the amount of energy that remains in the Earth’s climate system. The amount of energy trapped in the climate system increases due to the presence of greenhouse gases in the atmosphere: rather than shooting the energy back into space, it is used to heat the climate system. Simple physical laws, that make that more greenhouse gases cause a warmer climate. NASA’s Earth Observatory has an extensive explanation. Peter Neff Assistant Research Professor, University of Minnesota: This links back to the author’s earlier claim about ice cores, that they show increasing CO2 after “natural warming.” In this ancient scenario, he is correct that warming was caused by changes in Earth’s orbit around the Sun—which slightly but significantly affects the planetary energy budget. However, it is no longer the case that solely Earth’s orbit and solar radiation drive climate change. Solar energy reaching Earth has been declining for decades, as global average temperatures have continued to increase. Zeke Hausfather has nicely explained this. “Australia’s signed a suicide note [with the Paris Accord] yet didn’t seem to notice that China, India, Indonesia and the US did not commit to reducing their large carbon dioxide emissions.” Sara Vicca Postdoctoral research fellow, University of Antwerp: China and India are actually changing track. They need to because their people are dying of air pollution. And of course they have also realized that renewable energy is more profitable. See here fore much more information: https://www.worldenergy.org/publications/2017/world-energy-issues-monitor-2017/ Statement taken from the full report of 2017: “China is continuing to experience rapid growth in renewable energy capacity, with the country installing 30.8 GW of new wind capacity in 2015, and with government plans in place to build an additional 30.83 GW before the end of 2016. The country’s solar capacity, too, is increasing steadily and China has already overtaken Germany to become the country with the largest cumulative solar PV capacity globally. Regarding future investment in further renewables capacity, China claims the top spot in the 2015 Climatescope project, which ranks 55 emerging economies according to their ability to attract investment in clean energy, and places second globally after the US in Ernst and Young’s 2016 Renewable Energy Country Attractiveness Index.” “The grasslands, crops, forests and territorial waters of Australia absorb more carbon dioxide than Australia emits.” Ana Bastos Group Leader, Max Planck Institute for Biogeochemistry: This is not true. According to the CSIRO (see here): “Taking all fluxes together, the Australian biosphere gained carbon on average at 59 million tonnes of carbon per year (1 Mt = 1 Teragram, Tg) during the period 1990-2011. This amount is the equivalent to 62% of Australia’s emissions from fossil fuels for the same period (this calculation excludes the fossil fuel exports shown in the budget figure).” Source: CSIRO A thorough analysis of the Australian carbon budget can be found in Haverd et al*. Haverd et al (2013) The Australian terrestrial carbon budget, Biogeoscience

https://science.feedback.org/review/bbc-article-ocean-acidification-accurate-brief-roger-harrabin/

0.7

BBC, by Roger Harrabin, on 2017-10-23.

"More acidic oceans 'will affect all sea life'"

This BBC article describes an as-yet-unreleased report on ocean acidification from a major collaborative scientific project called BIOACID. The report will summarize the state of research on the impacts of ocean acidification—the changing pH and chemistry of seawater due to rising atmospheric carbon dioxide—on marine life. Scientists who reviewed the article found that it was generally accurate in its description of the forthcoming report’s overall conclusions that ocean acidification poses an important threat to marine ecosystems. However, the BIOACID report will cover a broad and complex field of research, very little of which is explained in this short article.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Lennart Bach Postdoctoral research fellow, GEOMAR Helmholtz Centre for Ocean Research Kiel: A good summary of BIOACID’s key results. The information provided here is based on peer-reviewed scientific articles. I am glad the author mentions the statement that “[…]even if an organism isn’t directly harmed by acidification it may be affected indirectly through changes in its habitat or changes in the food web.” I think these complex (and so far poorly understood) food web interactions deserve attention by both the public and the scientific community. It is also important that the author mentions that there are potential winners (e.g. macroalgae) in an acidified ocean and that not every organism is negatively affected. Jean-Pierre Gattuso Research Professor, CNRS, Université Pierre et Marie Curie and IDDRI: The German program BIOACID has generated an impressive amount of knowledge on ocean acidification and its impacts. The BBC article is based on a brochure that is not available to me. It does not contain any inaccuracies but only skims the surface of the issue by highlighting a few scientific results with just one sentence. The synthesis of more than 350 publications on the effects of ocean acidification alluded to would deserve an in-depth article to provide important insight and better explain implications of the science. Adam Subhas PhD candidate, Caltech: This article is a well-done presentation of a newly published long-term study on ocean acidification. Such studies are useful for documenting long-term, larger-scale effects and the author seemed to do a pretty good job in stating the findings accurately. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Featured Annotations: The statements quoted below are from the article; comments and replies are from the reviewers. “More acidic oceans ‘will affect all sea life’” Lennart Bach Postdoctoral research fellow, GEOMAR Helmholtz Centre for Ocean Research Kiel: “More acidic” is not entirely correct as the ocean is strictly speaking still alkaline (pH>7) and will remain so in the future. It is nevertheless true that the pH will most likely decrease (and has already done so in the past). A small change in the pH leads to large shifts in seawater carbonate chemistry (as the author correctly mentions later in the main text). The pH change will affect many species. I am not sure if the statement “all sea life” is justified at this stage. Indirect effects will likely play a major role here (as mentioned later in the text) but this still lacks evidence. This is more like “work in progress” I would say. “Since the beginning of the Industrial Revolution, the average pH of global ocean surface waters have fallen from pH 8.2 to 8.1. This represents an increase in acidity of about 26%.” Lennart Bach Postdoctoral research fellow, GEOMAR Helmholtz Centre for Ocean Research Kiel: Correct. “This means the number of baby cod growing to adulthood could fall to a quarter or even a 12th of today’s numbers, the researchers suggest.” Lennart Bach Postdoctoral research fellow, GEOMAR Helmholtz Centre for Ocean Research Kiel: This statement is based on on a study by Stiasny et al*. The authors write: “Here, we obtain first experimental mortality estimates for Atlantic cod larvae under OA and incorporate these effects into recruitment models. End-of-century levels of ocean acidification (~1100 μatm according to the IPCC RCP 8.5) resulted in a doubling of daily mortality rates compared to present-day CO2 concentrations during the first 25 days post hatching (dph), a critical phase for population recruitment. These results were consistent under different feeding regimes, stocking densities and in two cod populations (Western Baltic and Barents Sea stock). When mortality data were included into Ricker-type stock-recruitment models, recruitment was reduced to an average of 8 and 24% of current recruitment for the two populations, respectively. Our results highlight the importance of including vulnerable early life stages when addressing effects of climate change on fish stocks.” The author of the BBC article referred to their work correctly. Stiasny et al (2016) Ocean Acidification Effects on Atlantic Cod Larval Survival and Recruitment to the Fished Population, PLOS ONE “[Riebesell] is a world authority on the topic and has typically communicated cautiously about the effects of acidification.” Adam Subhas PhD candidate, Caltech: This is good to note, as it shows that scientists directly involved in the research are driven by these experiments to speak out about these effects now. “‘But even if an organism isn’t directly harmed by acidification it may be affected indirectly through changes in its habitat or changes in the food web.’” Lennart Bach Postdoctoral research fellow, GEOMAR Helmholtz Centre for Ocean Research Kiel: A very important statement which is often neglected. It is good that the author included this statement. “And some plants – like algae which use carbon for photosynthesis – may even benefit.” Lennart Bach Postdoctoral research fellow, GEOMAR Helmholtz Centre for Ocean Research Kiel: This sentence is not really wrong but imprecise. First, plants use carbon dioxide (or in the case of aquatic photosynthetic organisms CO2 and often bicarbonate). The term “carbon” is too general. Second, the sentence implies that only some plants use carbon dioxide. I am sure the author is aware that “all” plants use CO2 for photosynthesis. Adam Subhas PhD candidate, Caltech: The use of “carbon” here is confusing. However the statement is not totally wrong. It is fine in my opinion to say “some plants maybe benefit” because experiments have only been run on some types of plants and algae.

https://science.feedback.org/review/former-prime-minister-tony-abbott-wrongly-claims-australia-warmed-far-less-data-show/

Inaccurate

Global Warming Policy Foundation, Tony Abbott, 2017-10-09

unadjusted data suggests that temperatures in Australia have only increased by 0.3 degrees over the past century, not the 1 degree usually claimed

Factually inaccurate: Observations clearly show that Australia has warmed by around 1 °C. Incorrect: IPCC projections have compared well with the observed warming trend.

Globally, weather station data show that the world has warmed by roughly 1 °C so far–as has Australia. The warming trend over the last couple decades has matched climate model projections made during that time period.

It may be that a tipping point will be reached soon and that the world might start to warm rapidly but so far reality has stubbornly refused to conform to the Intergovernmental Panel on Climate Change’s computer modelling. [...] So far, though, there’s no concession that their models might require revision even though unadjusted data suggests that the 1930s were actually the warmest decade in the United States and that temperatures in Australia have only increased by 0.3 degrees over the past century, not the 1 degree usually claimed.

Peter Thorne Professor, Maynooth University: The global warming signal over the instrumental record is far larger in the unadjusted than the adjusted record. You can’t pick and choose which adjustments you happen to like. Adjustments are essential because observation techniques have changed through time and this introduces data artefacts that are not a true portrayal of the underlying climate. We have tested, replicated, and benchmarked techniques to build confidence in the techniques deployed to account for these. The choice is stark: trust the unadjusted data we know to be wrong and that shows more warming, or trust the adjusted data which has been verified scientifically many times over to improve the estimates and shows less warming. “reality has stubbornly refused to conform to the Intergovernmental Panel on Climate Change’s computer modelling” Markus Donat Research Fellow, University of New South Wales: This claim is wrong. For example, this study by Rahmstorf and colleagues* shows how projections from past IPCC reports (future projections starting in 1990 and 2000) very well predicted the observed temperature changes since then. Figure –Observed annual global temperature, unadjusted (pink) and adjusted for short-term variations due to solar variability, volcanoes and ENSO (red)compared to the scenarios of the IPCC (blue range and lines from the third assessment, green from the fourth assessment report). Source:Rahmstorf et al (2012) Rahmstorf et al (2012) Comparing climate projections to observations up to 2011, Environmental Research Letters “data suggests that the 1930s were actually the warmest decade in the United States” Markus Donat Research Fellow, University of New South Wales: It is true that the eastern part of the US is different than most of the globe with regards to temperature changes. While temperatures have been rising in most regions of the world, the eastern US is known as the so-called “warming hole” because this is one of the few regions where we do not see clear long-term warming. But using this as an argument against global warming is simply nonsense and comparable to picking one rotten cherry out of a bucket with 1,000 otherwise perfect cherries, and claiming the whole bucket of cherries is rotten. The hot temperatures in the 1930s in the US were related to a very specific coincidence of variability patterns favouring the occurrence of hot extremes (see also this study*). But if this coincidence of variability patterns would occur today in a warmer world, the records set in the 1930s would surely be broken also in this region of the world. Donat et al (2016) Extraordinary heat during the 1930s US Dust Bowl and associated large-scale conditions, Climate Dynamics “temperatures in Australia have only increased by 0.3 degrees over the past century, not the 1 degree usually claimed.” Markus Donat Research Fellow, University of New South Wales: I don’t know what the source of these numbers is. The official data for Australia by the Bureau of Meteorology, based on high-quality observations, clearly shows that average temperatures have warmed by 0.9-1 degree since 1910. Source: BOM

https://science.feedback.org/review/new-york-times-straightforward-answers-common-climate-questions-accurate-justin-gillis/

1.4

The New York Times, by Justin Gillis, on 2017-09-19.

"Climate Change Is Complex. We’ve Got Answers to Your Questions."

This article in The New York Times serves as a primer by briefly answering seventeen basic questions about the cause and consequences of—and possible solutions to—climate change. Thirteen scientists reviewed the article, and generally found the answers to be highly accurate distillations of the research on that topic. There are only a few instances where answers—mainly to questions about efforts to reduce greenhouse gas emissions—are worded in an imprecise way that could lead to readers misunderstanding the state of scientific knowledge.See all the scientists’ annotations in context This is part of a series of reviews of 2017’s most popular climate stories on social media.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Ted Letcher Research Scientist, Cold Regions Research and Engineering Lab: The article provided a quick and remarkably concise “listicle” style explanation of the key questions surrounding climate change. I saw no red flags, or blatant attempts to mislead the reader. Furthermore, every major scientific claim has a link to a peer reviewed article. The article largely avoids hyperbole as well as alarmist and inflammatory language, which is laudable. I also want to highlight the section that talks about the various solutions and opportunities for action. Overall, a good article that hits all the key point, speaks in plain English, and treats the reader with enough respect to look deeper into any one issue. Joeri Rogelj Professor, Centre for Environmental Policy at Imperial College London: The article provides a fair and correct account of the state of the science in my area of expertise. Some statements could be slightly more informative when the article speaks about “experts”. It is not clear who these experts are. In some cases “expert” views are used to support statements which are dependent on societal value judgments, and would benefit from some clarification. Daniel Swain Climate Scientist, University of California, Los Angeles: The accuracy of the climate information provided in this piece is generally quite high. Further, the “question and answer” format distills complex, ongoing scientific conversations into a form more readily accessible to a broad audience. Benjamin Horton Professor, Earth Observatory of Singapore: Climate change is one of the most complex areas of scientific study, so it is understandable that the general public find the topic difficult to grasp. But this article provides the readers of The New York Times the chance of understanding the topic. Lennart Bach Postdoctoral research fellow, GEOMAR Helmholtz Centre for Ocean Research Kiel: The article is well written. The author used little “alarmist” jargon and used “strong” adjectives only in cases where there is good scientific evidence for strong impacts. Devaraju Narayanappa Postdoctoral research fellow, Université de Versailles Saint-Quentin (UVSQ-CEA-CNRS): The article provides a simple answer to overarching questions on global warming/climate change and its footprints. Malte Stuecker Postdoctoral research fellow, University of Washington: The article presents short but accurate statements on climate change and its framing. Victor Venema Scientist, University of Bonn, Germany: As far as I can judge, very accurate. A pleasure to read. There should be more science reporting like this. Frank Vöhringer Dr. rer. pol, Scientist, Ecole Polytechnique Fédérale de Lausanne (EPFL): The article provides an informative overview of climate and climate policy facts with only minor inaccuracies. Ana Bastos Group Leader, Max Planck Institute for Biogeochemistry: Overall the article frames the questions correctly and provides generally good answers. However, it presents some aspects in a rather simplified and incomplete manner (e.g. consequences of global warming or mitigation solutions). Didier Swingedouw Researcher, CNRS (French National Center for Scientific Research): The article is mainly accurate for most of its assertions. Some of them are bit subjective and possibly alarmist, but generally speaking the author is very well informed concerning general understanding that we have of global warming and its impact (as released in IPCC report for instance). Dan Jones Physical Oceanographer, British Antarctic Survey: Although there are places where the language is a little imprecise (e.g. the word “ever” in the statement “Geologists say that humans are now pumping the gas into the air much faster than nature has ever done”), overall the article is an accurate, concise summary of climate change as a scientific and social issue. Kelly McCusker Research Associate, Rhodium Group and Climate Impact Lab: The article does a good job of succinctly answering complex questions without misrepresenting the scientific evidence.Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Featured Annotations: The statements quoted below are from the article; comments and replies are from the reviewers. How much is the Earth heating up? “Climate change? Global warming? What do we call it? […]You can think of global warming as one type of climate change. The broader term covers changes beyond warmer temperatures, such as shifting rainfall patterns.” Daniel Swain Climate Scientist, University of California, Los Angeles: This is a good way to describe the difference in language. It would also be reasonable to say that global warming (the increase in Earth’s average temperature) causes climate change (shifts in the location/frequency/intensity of weather patterns). In practice, the two terms are often used somewhat imprecisely and interchangeably (even in the scientific literature). Kelly McCusker Research Associate, Rhodium Group and Climate Impact Lab: It is also worth noting that global warming refers to global average temperature rising, but this does not necessarily mean that all locations across the globe are warming at all times. “the oceans are rising at an accelerating pace” Kelly McCusker Research Associate, Rhodium Group and Climate Impact Lab: Because more than 90% of the energy added to the climate system is being stored in the ocean, causing sea level rise through thermal expansion. The latest IPCC report states, “Ocean warming dominates the increase in energy stored in the climate system, accounting for more than 90% of the energy accumulated between 1971 and 2010 (high confidence).” “Two degrees is more significant than it sounds. […]The number may sound low, but as an average over the surface of an entire planet, it is actually high” Daniel Swain Climate Scientist, University of California, Los Angeles: This is an important point. “Global mean temperature” (GMT) is a pretty abstract quantity, since it doesn’t reflect any particular location on Earth. Instead, GMT serves as a useful indicator of how much the Earth’s climate has changed overall. While a helpful statistical construct, it masks the fact that the Earth is warming much faster than the global average in some regions (over land, in the Arctic) than in others (over the oceans). Victor Venema Scientist, University of Bonn, Germany: Note that the warming over land is about twice as large as the warming over the ocean. Over the ocean, more of the additional heat goes into evaporation of water rather than warming of the air. It furthermore takes time to heat up the oceans, just like a water kettle takes time to boil. Because there is more land in the Northern Hemisphere, it will warm more than the Southern Hemisphere. One way to see how much of a difference two degrees makes is to look at a region closer to the equator that is two degrees warmer. Nature will look very different. “We’ve known about [the greenhouse effect] for more than a century. Really.” Daniel Swain Climate Scientist, University of California, Los Angeles: As the author correctly notes, the underlying chemistry dates back to the late 1880s. “The first prediction that the planet would warm as humans released more of the gas was made in 1896.” Ed Hawkins Principal Research Fellow, National Centre for Atmospheric Science: Arrhenius didn’t actually discuss human emissions in 1896—he was speculating about causes of the ice ages. But, he did effectively make a prediction that warming would occur if carbon dioxide levels increased (whatever their source). “[CO2] has increased 43 percent above the pre-industrial level so far” Lennart Bach Postdoctoral research fellow, GEOMAR Helmholtz Centre for Ocean Research Kiel: Indeed! I get to a slightly different number, however, (45 %) maybe because I used a different basis (280 ppm) and/or current CO2 value (i.e., 405 ppm from Maona Loa, August 2017). The message is correct! How do we know humans are responsible for the increase in carbon dioxide? “Hard evidence, including studies that use radioactivity to distinguish industrial emissions from natural emissions, shows that the extra gas is coming from human activity.” Victor Venema Scientist, University of Bonn, Germany: Also important is that we have good estimates of how much fossil fuel we have burned, from which one can estimate the CO2 emissions. The increase in CO2 concentration in the atmosphere is about half of those emissions (the rest was taken up by the vegetation and the oceans). It would have been more accurate to say that we can see that the CO2 increase is from burning fossil fuels by measuring isotopes (differences in the number of nuclear particles of atoms). Not all relevant isotopes are radioactive and the ones that are only a little. “Geologists say that humans are now pumping the gas into the air much faster than nature has ever done.” Daniel Swain Climate Scientist, University of California, Los Angeles: “Ever” is a long time, and it’s not clear this is strictly true for the entire length of Earth’s history. But there is strong evidence that this statement is true for all human-relevant timescales: in other words, the rate of CO2 emissions caused by humans is unprecedented since the age of the dinosaurs (i.e., at least 66 million years ago*). Zeebe et al (2016) Anthropogenic carbon release rate unprecedented during the past 66 million years, Nature Could natural factors be the cause of the warming? “Could natural factors be the cause of the warming? Nope.” Victor Venema Scientist, University of Bonn, Germany: We are sure that natural factors alone could not have caused the observed warming—without the increase of greenhouse gases there would not be so much warming—but they could have contributed. For the period 1951 to 2010 our best estimate is that all of the warming was due to human activities. But natural factors could have warmed or cooled the Earth a bit. In the period around 1900, part of the warming was probably natural due to fewer volcanic eruptions and a stronger Sun. [Also see this related Claim Review. ] “The warming is extremely rapid on the geologic time scale, and no other factor can explain it as well as human emissions of greenhouse gases.” Daniel Swain Climate Scientist, University of California, Los Angeles: This accurate statement succinctly summarizes decades of scientific research across a wide range of disciplines. Why do people deny the science of climate change? “Instead of negotiating over climate change policies and trying to make them more market-oriented, some political conservatives have taken the approach of blocking them by trying to undermine the science.” Victor Venema Scientist, University of Bonn, Germany: This is mostly just in the USA. In the rest of the world, conservative parties accept the science of climate change. Ana Bastos Group Leader, Max Planck Institute for Biogeochemistry: On the scientific community side, the consensus is broad. It’s worth revisiting Cook et al. 2015*. In their review they find a 97% consensus about human-induced global warming in published climate studies. Cook et al (2016) Consensus on consensus: a synthesis of consensus estimates on human-caused global warming, Environmental Research Letters What could happen? “Over the coming 25 or 30 years, scientists say, the climate is likely to gradually warm” Ted Letcher Research Scientist, Cold Regions Research and Engineering Lab: While the exact details and timing of warming are subject to unpredictable decadal (semi-decadal) climate variability (e.g. El Niño Southern Oscillation, Pacific Decadal Oscillation, Atlantic Multidecadal Oscillation), this statement is largely true. “Longer term, if emissions rise unchecked, scientists fear climate effects so severe that they might destabilize governments, produce waves of refugees, precipitate the sixth mass extinction of plants and animals in the Earth’s history, and melt the polar ice caps, causing the seas to rise high enough to flood most of the world’s coastal cities. The emissions that create those risks are happening now, raising deep moral questions for our generation.” Ed Hawkins Principal Research Fellow, National Centre for Atmospheric Science: This paragraph suggests that the emissions that will precipitate the sixth mass extinction are happening now, which I think is misleading. We can stop those impacts by reducing our emissions. How much will the seas rise? “The ocean has accelerated and is now rising at a rate of about a foot per century[…] The risk is that the rate will increase still more. Scientists who study the Earth’s history say waters could rise by a foot per decade in a worst-case scenario, though that looks unlikely. Many experts believe that even if emissions stopped tomorrow, 15 or 20 feet of sea level rise is already inevitable, enough to flood many cities unless trillions of dollars are spent protecting them. How long it will take is unclear. But if emissions continue apace, the ultimate rise could be 80 or 100 feet.” Benjamin Horton Professor, Earth Observatory of Singapore: It is accurate to say sea-level rise is approximately one foot per century. Present-day sea-level rise is a major indicator of climate change. Since the early 1990s, sea level rose at a mean rate of ~3.1 mm/yr (~1 foot over 100 years). It is virtually certain that global mean sea level rise will continue for many centuries beyond 2100, with the amount of rise dependent on future emissions. The latest IPCC report estimates 1 to more than 3 m (up to ~10 feet) for high emission scenarios by 2300. But, those projections of sea-level rise may be limited by uncertainties surrounding the response of the Greenland and Antarctic ice sheets. For example, the report projected a likely contribution of the Antarctic ice sheet (AIS) of -8 to +15 cm under the high emissions scenario by 2100, but a recent coupled ice sheet and climate dynamics model suggests that the AIS could contribute more than 1 m by 2100, and more than 10 m by 2300, under that high emissions scenario. Is recent crazy weather tied to climate change? “Is recent crazy weather tied to climate change? Some of it is.” Daniel Swain Climate Scientist, University of California, Los Angeles: This is a reasonable short answer to an extremely challenging scientific question. “Scientists have published strong evidence that the warming climate is making heat waves more frequent and intense. It is also causing heavier rainstorms” Ana Bastos Group Leader, Max Planck Institute for Biogeochemistry: It is hard to attribute each particular event to human-induced climate change. The article correctly frames the influence in terms of increasing frequency and intensity of extremes, and directs the reader to a good reference page with clear explanations for non-experts. Daniel Swain Climate Scientist, University of California, Los Angeles: Indeed, there is now observational evidence that global warming has already increased the likelihood and magnitude of extreme heat and intense downpours across much of the globe*. Diffenbaugh et al (2017) Quantifying the influence of global warming on unprecedented extreme climate events, PNAS “In many other cases, though — hurricanes, for example — the linkage to global warming for particular trends is uncertain or disputed.” Daniel Swain Climate Scientist, University of California, Los Angeles: The question of whether global warming will affect the frequency of hurricanes is indeed an open one, and research continues. There is stronger evidence, however, that warming will increase the maximum “intensity ceiling”/intensification rate1 of the strongest storms, the maximum rainfall associated with tropical cyclones2, and the magnitude of oceanic “storm surges”3 that occur in an era of rising seas. 1- Emanuel (2017) Will Global Warming Make Hurricane Forecasting More Difficult?, BAMS 2- Scoccimarro et al (2017) Tropical Cyclone rainfall changes in a warmer climate 3- Lin et al (2016) Hurricane Sandy’s flood frequency increasing from year 1800 to 2100, PNAS Are there any realistic solutions to the problem? “But as long as there are still unburned fossil fuels in the ground, it is not too late to act.” Joeri Rogelj Professor, Centre for Environmental Policy at Imperial College London: This statement is imprecise, and depends on value judgments of what “too late” means. Even emitting only a fraction of the available unburned fossil fuels would eliminate important ecosystems like coral reef habitats. For these ecosystems it will thus be too late. Because part of the CO2 that is emitted will remain in the atmosphere for many centuries, climate change constitutes a cumulative problem. Halting CO2 emissions before the last fossil fuel has been burned thus indeed commits the world to less impacts than the theoretically maximum. However, whether this is not “too late” depends on whether no irreversible or societally unacceptable impacts were reached before that point. The latter requires societal value judgments informed by scientific assessments, but is ultimately not a scientific question. Frank Vöhringer Dr. rer. pol, Scientist, Ecole Polytechnique Fédérale de Lausanne (EPFL): This is incorrect, at least if we want to stay anywhere near the 2 degree C target. Especially coal reserves are so abundant (and there is coal gasification and coal liquefaction) that by far the largest part of them have to stay in the ground. “The warming will slow to a potentially manageable pace only when human emissions are reduced to zero.” Joeri Rogelj Professor, Centre for Environmental Policy at Imperial College London: The current understanding of interactions between the global carbon cycle and the climate system is that when global CO2 emissions are reduced to zero, the warming will remain approximately constant. This is very often confused by estimates of committed “warming in the pipeline” which instead of assuming that global emissions are reduced to zero, assume that concentrations (and therewith to a large degree forcing) are kept constant. Keeping CO2 concentrations constant would require continuous emissions of CO2 that perfectly counter the uptake by natural sinks. If CO2 emissions are reduced to zero, atmospheric CO2 concentrations will gradually decline. For heat-trapping emissions other than CO2, the requirement to reduce them to zero to stabilize warming depends on their residence time in the atmosphere. For gases and particles that only stay in the atmosphere for shorter time periods (days to a decade) achieving constant emissions would also achieve approximately stabilized warming. “But experts say the energy transition needs to speed up drastically to head off the worst effects of climate change.” Joeri Rogelj Professor, Centre for Environmental Policy at Imperial College London: This is correct. While many countries show gradual declines in their emissions, global emissions are not yet declining. The past few years, global annual CO2 emissions have not increased as much as they did previously and remained roughly constant. However, to halt global mean temperature rise annual CO2 emissions have to become zero. Does clean energy help or hurt the economy? “Converting to these cleaner sources [of energy] may be somewhat costlier in the short term, but they could ultimately pay for themselves by heading off climate damages and reducing health problems associated with dirty air.” Kenneth Gillingham Associate Professor, Yale University: The basic idea of this sentence is correct—that these cleaner sources may be somewhat costlier in the short run, but they also provide benefits that offset the short-run costs. The second part of the sentence is technically correct given that it uses the word “could,” which provides a lot of leeway. A more complete story is that a switch towards these cleaner technologies on the margin for electricity would pay for itself given reasonable estimates of the health costs of fossil fuel generation and the social cost of carbon. It’s also worth noting though that an immediate switch entirely to these technologies would incur transition costs that would likely tip the balance in the cost-benefit analysis, depending on the social cost of carbon used and what sectors we are talking about (are we talking about just electricity? industry? transport?). The vagueness of the statement means that it is less meaningful, but more difficult to critique. Ana Bastos Group Leader, Max Planck Institute for Biogeochemistry: The article does not mention the huge subsidies to the fossil fuel industry worldwide. According to the World Energy Outlook 2016, fossil-fuel subsidies were around $325 billion in 2015 ($490 billion in 2014) against 150 billion for renewables. “Burning gas instead of coal in power plants reduces emissions in the short run, though gas is still a fossil fuel and will have to be phased out in the long run.” Frank Vöhringer Dr. rer. pol, Scientist, Ecole Polytechnique Fédérale de Lausanne (EPFL): It is arguable whether natural gas is a reasonable solution even in the short run. I argued in favor of this 20 years ago, but nowadays we have to cut emissions more drastically than would be possible by switching to another fossil fuel. The CO2 coefficient of natural gas is still about 2/3 of that of coal. Efficiency factors of power plants are also somewhat better for natural gas than for coal. Overall, we might save a bit more than half of the emissions by switching to natural gas while renewables can save much more. Furthermore, given the long technical lifetime of power stations, the “short run” could easily extend to 2060 or more. “‘Clean coal’ is an approach in which the emissions from coal-burning power plants would be captured and pumped underground.” Joeri Rogelj Professor, Centre for Environmental Policy at Imperial College London: It is important to note that up to the present, the capture of CO2 is not perfect. While theoretically some CO2 emissions could be avoided, a residual amount would still leak into the atmosphere. As CO2 accumulates in the atmosphere, it would either lead to continued (yet slower) warming, or have to be compensated by the active removal of CO2 from the atmosphere, which is also not yet proven to work economically. “some countries are already talking about banning the sale of gasoline cars after 2030” Frank Vöhringer Dr. rer. pol, Scientist, Ecole Polytechnique Fédérale de Lausanne (EPFL): It’s not only talk. Great Britain has already decided in favor of such a ban by 2040. Climate change seems so overwhelming. What can I personally do about it? “Experts say the problem can only be solved by large-scale, collective action” Kenneth Gillingham Associate Professor, Yale University: This is correct. Our atmosphere is a global public good and addressing the issue requires large-scale action by most players. “Entire states and nations have to decide to clean up their energy systems” Kenneth Gillingham Associate Professor, Yale University: This is correct. It cannot be done by only a few nations—it requires collective action to make a substantial difference. “Entire states and nations have to decide to clean up their energy systems, using every tool available and moving as quickly as they can.” Kenneth Gillingham Associate Professor, Yale University: This is not universally agreed upon by experts. The key issue is that it is imprecisely written. I would not be surprised if the intent is correct. But taking it as it is written, it is not clear what “every tool available” includes. Technically, this should include truly everything, including simply shutting down all manufacturing that uses fossil fuels at all. Banning the driving of any vehicle except electric vehicles run on renewables. Banning flying. I doubt that was the intent of the sentence. The same issue holds for “moving as quickly as they can.” What are the limits to”as quickly as they can”? Does it including shutting down the economy? Or is the intended sentence “moving as quickly as they cost-effectively can”? Thus, in short, while the idea is correct, this is imprecisely worded and can easily be critiqued. Ana Bastos Group Leader, Max Planck Institute for Biogeochemistry: “Using every tool available” is highly debatable, as even tools which are usually perceived to help mitigating climate (e.g. reforestation), may not result in mitigation effects, depending on how they are implemented. A study on European forests* has shown that afforestation since 1750 was responsible for an increase of 0.12 watts per square meter in the radiative imbalance at the top of the atmosphere, rather than a decrease, because of management choices. Naudts et al (2016) Europe’s forest management did not mitigate climate warming, Science “You can plug leaks in your home insulation to save power, install a smart thermostat, switch to more efficient light bulbs, turn off unused lights, drive fewer miles by consolidating trips or taking public transit, waste less food, and eat less meat.” Ana Bastos Group Leader, Max Planck Institute for Biogeochemistry: According to a recent study*, having fewer children has the largest impact on personal carbon footprint. Wynes and Nicholas (2017) The climate mitigation gap: education and government recommendations miss the most effective individual actions, Environmental Research Letters

https://science.feedback.org/review/daily-wire-article-incorrectly-claims-climate-models-have-overestimated-warming/

Incorrect

The Daily Wire, James Barrett, 2017-09-19

climate models have overestimated the amount of global warming and failed to predict what climatologists call the warming ‘hiatus’

Factually inaccurate: Observed temperatures have actually stayed within the range of model projections. Misleading: Climate model projections show average long-term trends—by nature they will not "predict" short-term variability such as the "hiatus" period.

Climate models have, in fact, successfully projected the rate of global warming, comparing well with observed global temperature in recent years. The idea that models should be faulted for not predicting the "hiatus"—the period in the early 2000s during which temperatures stayed below the long-term trend—reflects a misunderstanding of what a model projection is.

climate models have overestimated the amount of global warming and failed to predict what climatologists call the warming ‘hiatus’, over 20 years of almost no change in temperatures.

Pierre Friedlingstein Professor, University of Exeter: Except that the report (the paper published in Nature Geoscience) never said that. The paper does not describe modelled warming vs. observations over the “hiatus” period. Ed Hawkins Principal Research Fellow, National Centre for Atmospheric Science: Recent media headlines have again discussed the issue of whether climate models are overly sensitive to greenhouse gases. These headlines have misinterpreted a study by Millar et al. which was discussing carbon budgets to limit global temperature rise to 1.5°C above pre-industrial levels. A recent study by Medhaug et al. analysed the issue of how the models have performed against recent observations at length and largely reconciled the issue. An overly simplistic comparison of simulated global temperatures and observations might suggest that the models were warming too much, but this would be wrong for a number of reasons. In the Medhaug et al. paper they show the range of models (blue shading in figure with median in light blue), compared with the HadCRUT4 observations and their estimated uncertainty (orange shading with light orange line). There are a number of well understood reasons why the light orange line might not follow the light blue line, namely: radiative forcings, variability, observational biases and choice of reference period. [Read more…] Figure 5 from Medhaug et al. showing CMIP5 simulations and observations (HadCRUT4) of global temperature. Medhaug et al (2017) Reconciling controversies about the ‘global warming hiatus’, Nature Markus Donat Research Fellow, University of New South Wales: [This comment comes from an evaluation of a similar statement.] For one example, this study by Rahmstorf and colleagues* shows how projections from past IPCC reports (future projections starting in 1990 and 2000) very well predicted the observed temperature changes since then. Figure –Observed annual global temperature, unadjusted (pink) and adjusted for short-term variations due to solar variability, volcanoes and ENSO (red)compared to the scenarios of the IPCC (blue range and lines from the third assessment, green from the fourth assessment report). Source:Rahmstorf et al (2012) Rahmstorf et al (2012) Comparing climate projections to observations up to 2011, Environmental Research Letters Reto Knutti Professor, ETH Zürich: [This comment comes from an evaluation of a similar statement.] Statements that climate models overestimate the warming in response to CO2are incorrect; they are based on either too short time periods that are dominated by natural variability, by the comparison of models with datasets that do not have global coverage, by comparing to models that were run many years ago with emissions and forcings that differed from what actually happened, by the use of oversimplified energy balance models1, or a combination of these. Recent studies have shown that once the changes in climate feedbacks over time2, datasets with full coverage3,and all forcings are considered, the agreement between predicted and observed warming is excellent, even over the recent hiatus period4. It is remarkable that even projections made decades ago with climate models that were much simpler (and were running on computers that were likely slower than a mobile phone today) were quite accurate5,6,7. 1- Knutti and Rugenstein (2015) Feedbacks, climate sensitivity and the limits of linear models, Philosophical Transactions of the Royal Society A 2- Armour (2017) Energy budget constraints on climate sensitivity in light of inconstant climate feedbacks, Nature Climate Change 3- Richardson et al (2016) Reconciled climate response estimates from climate models and the energy budget of Earth, Nature Climate Change 4- Medhaug et al (2017) Reconciling controversies about the ‘global warming hiatus’, Nature 5- Stouffer and Manabe (2017) Assessing temperature pattern projections made in 1989, Nature Climate Change 6- Fischer and Knutti (2016) Observed heavy precipitation increase confirms theory and early models, Nature Climate Change 7- Allen et al (2013) Test of a decadal climate forecast, Nature Geoscience

https://science.feedback.org/review/daily-wire-article-misunderstands-study-carbon-budget-along-fox-news-telegraph-daily-mail-breitbart-james-barrett/

-1.7

The Daily Wire, by James Barrett, on 2017-09-19.

"Climate Scientists: Climate Models Have Overestimated Global Warming"

This story at The Daily Wire describes a new study that evaluates the remaining amount of greenhouse gas that we can emit before global temperature rises to 1.5 °C above pre-industrial times. The study suggests that we may have a little more room in the so-called “carbon budget” than previously estimated. Scientists who reviewed the Daily Wire article found that it greatly misinterpreted the study by saying that it showed that climate projections have overestimated warming. This is incorrect. The study does not conclude that climate models are overly sensitive to warming, or that future warming will be less than projected. Instead, it investigates a discrepancy between the total amount of greenhouse gas emitted since the Industrial Revolution in the models and in the real world. This difference in estimated past emissions affects the study’s calculation of the remaining “carbon budget” for future emissions. According to the study’s authors, articles implying their work “indicates that global temperatures are not rising as fast as predicted” (as published in Fox News, The Telegraph, The Daily Mail, Breitbart…) do not represent their work. Describing the inaccurate coverage of their study, two of the authors wrote, “Crucially, the reason for the correction [of the carbon budget] was not that we had a new estimate of the climate response, or warming per tonne of CO2 emitted—we used exactly the current consensus range—but that we took better account of past emissions and where human-induced warming has got to already.”See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Andrew MacDougall Assistant Professor, St. Francis Xavier University: The article selectively quotes from interviews and scientific papers to create the false perception that climate models significantly overestimate the rate of warming. The article also falsely implies that the cited paper is about the so called “hiatus” while the paper is actually about the carbon budget for the 1.5 ºC target. Pierre Friedlingstein Professor, University of Exeter: [Prof. Friedlingstein is a co-author of the Millar et al study described by the Daily Wire story.] Bad coverage of the Nature Geoscience article. The title and first 3 paragraphs are misleading. It seems very clear that the author of this article did not read the scientific article he is reporting on. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Featured Annotations: “Climate Models Have Overestimated Global Warming” Pierre Friedlingstein Professor, University of Exeter: The title does not truly reflect the article in Nature Geoscience. The issue is not that the models are too warm by 2015. CMIP5 models are on the warm end, yes, but that’s not the main issue here. The article explains that problem comes when looking at both cumulative CO2 emissions and associated warming. The cumulative CO2 emissions simulated by the models only reach 545 GtC (the present-day value) after 2020, by which time the CMIP5 ensemble-mean human- induced warming is over 0.3 ºC warmer than the central estimate for human-induced warming to 2015. “The models end up with a warming which is larger than the observed warming for the current emissions.” Pierre Friedlingstein Professor, University of Exeter: That’s a more accurate description of the study. “For the current emissions” is the key element. “the climate models have overestimated the amount of global warming and failed to predict what climatologists call the warming ‘hiatus’” Pierre Friedlingstein Professor, University of Exeter: Except that the report (the paper published in Nature Geoscience) never said that. The paper does not describe modelled warming vs. observations over the “hiatus” period. Ed Hawkins Principal Research Fellow, National Centre for Atmospheric Science: Recent media headlines have again discussed the issue of whether climate models are overly sensitive to greenhouse gases. These headlines have misinterpreted a study by Millar et al. which was discussing carbon budgets to limit global temperature rise to 1.5°C above pre-industrial levels. A recent study by Medhaug et al. analysed the issue of how the models have performed against recent observations at length and largely reconciled the issue. An overly simplistic comparison of simulated global temperatures and observations might suggest that the models were warming too much, but this would be wrong for a number of reasons. In the Medhaug et al. paper they show the range of models (blue shading in figure with median in light blue), compared with the HadCRUT4 observations and their estimated uncertainty (orange shading with light orange line). There are a number of well understood reasons why the light orange line might not follow the light blue line, namely: radiative forcings, variability, observational biases and choice of reference period. [Read more…] Figure 5 from Medhaug et al. showing CMIP5 simulations and observations (HadCRUT4) of global temperature. Medhaug et al (2017) Reconciling controversies about the ‘global warming hiatus’, Nature “The report, published in the journal Nature Geoscience on September 18, acknowledges that most of the models of warming trends failed to predict the ‘slowdown’ in warming post-2000, resulting in less pronounced warming than predicted and thus more room in the CO2 ‘emissions budget’ for the coming decades.” Andrew MacDougall Assistant Professor, St. Francis Xavier University: Millar et al. (2017) does not mention the “hiatus” nor a slow-down in global warming post 2000, but is instead focused on estimating the remaining carbon budget compatible with remaining below the 1.5 ºC target set by the Paris agreements. Instead of looking at the carbon budget from pre-industrial times to present, the study uses the present decade (2010-2019) as the reference period and asks: How much more CO2 can we emit and remain below an addition 0.6 ºC of warming? The study found that the remaining carbon budget for the 1.5 ºC target was about ~200 GtC, which is larger than that found using pre-industrial times as the reference period. This implies that either (1) models may underestimate the historical strength of natural carbon sinks, (2) that the historical cumulative CO2 emissions (545±150 GtC, 2 standard deviations) are at the low end of the uncertainty bound, (3) or a combination of these and other factors. Ana Bastos Group Leader, Max Planck Institute for Biogeochemistry: There is an ongoing discussion about the reasons for models to overestimate the rates of tropospheric temperature in the early 21st century. In a recent study, Santer and colleagues* show that the observed cooling relative to the model predictions could be explained by both internal variability in the climate system (transition to a negative phase of the Interdecadal Pacific Oscillation in ca. 1999 and other modes) and by systematic errors in the models’ forcing that lead to an overestimation of the radiative forcing in the early 21st century. These errors include a later start of a minimum in solar cycle activity than have been assumed in CMIP5 simulations, and the cooling effect of both human and natural aerosol emissions. Schmidt and colleagues* have shown that if adjusted for such effects, CMIP5 models reproduced the slow-down of the warming trends (figure below). Source: Schmidt et al (2014)* Santer et al (2017) Causes of differences in model and satellite tropospheric warming rates, Nature Geoscience Schmidt et al (2014) Reconciling warming trends, Nature Geoscience “over 20 years of almost no change in temperatures” Ana Bastos Group Leader, Max Planck Institute for Biogeochemistry: Bastos There has been a slow-down in global mean surface (troposphere) temperatures, but this does not call into question the fact that the Earth-system as a whole is warming. In fact, during the so-called “hiatus”, the net radiation imbalance in the top of the atmosphere persisted (implying that warming would continue even if emissions were to stop). In fact, at the same time that warming in the troposphere stalled, ocean heat content increased, especially in deeper layers: The fact that oceans took more heat from the atmosphere helps to explain the slow-down of warming at the surface. This seems to be, at least partly, explained by natural variability in the ocean (see here). Trenberth* argued, thus, that natural variability in the climate system makes the global mean surface temperature record increase in steps, rather than in a linear way. In another study, Yan and colleagues* analysed the redistribution of heat during the “hiatus” period and concluded that: “[…] the term ‘global warming hiatus’ is a misnomer, although we will continue to use the widely used phrase to describe the slowdown or pause in the increase of GMST in the late 20th to early 21st century, with quotation marks. Alternatively, we would like to suggest to the climate community to use ‘global surface warming slowdown’ instead in the future to avoid confusion. There is no absolute consensus on the specific oceanic sink for the excess heat that led to the slowdown in rising GMST (the Southern Ocean may be worth further attention though), but there is a general agreement in this group and in the literature that rather than a ‘global warming hiatus,’ the slowdown of GMST increase in 1998–2013 was a result of the increased uptake of heat energy by the global ocean during those years.” Trenberth (2015) Has there been a hiatus?, Science Yan et al (2016) The global warming hiatus: Slowdown or redistribution?, Earth’s Future “The report follows a study by another team of climate scientists published in June 2017 [Santer et al] that likewise determined that the actual increases in warming post-2000 was ‘generally smaller than trends estimated’ from the models.” Andrew MacDougall Assistant Professor, St. Francis Xavier University: Santer et al. (2017)* attributed the small discrepancy between climate model simulated warming and observed warming to differences in scenario forcing. (i.e., the trajectory of CO2, methane, other greenhouse gasses and aerosols) The models were given the forcing that actually transpired between year 2000 and the present day. That is, the study suggested that the discrepancy is not a problem with our models but a problem with measuring emissions of forcing agents and discrepancies between future scenarios and what actually transpired since the scenarios were designed. Santer et al (2017) Causes of differences in model and satellite tropospheric warming rates, Nature Geoscience “The team of climate scientists notes that in failing to predict the warming ‘hiatus’ in the beginning of the 21st century, the Intergovernmental Panel on Climate Change (IPCC) models overestimated temperature increases…” Pierre Friedlingstein Professor, University of Exeter: The word hiatus is not even mentioned in the paper! Prof. Piers Forster, one of the authors of the Millar et al study, asked by Carbon Brief to further clarify some of the paper’s findings and methodologies in light of the media coverage: Our paper focused on carbon emissions and the feasibility of limiting future warming to 1.5 ºC. We concluded that we would only succeed with strengthened policies to bring rapid and sustained emission reduction. We made estimates of the allowable future emissions of carbon before we pass 1.5 ºC. To do this we made assumptions about past warming, exploring different levels of warming from 2015 to address the role of uncertainty in historic warming levels. Readers should note that our method is only one way of computing the budget. The IPCC special report on 1.5 ºC will need to consider it alongside other lines of evidence. The usefulness of the carbon budget concept will also likely be assessed given its inherent uncertainty due to the uncertain historic warming. I think some press reporting is misleading as our paper did not assess climate impacts or climate model performance. Rather, our paper confirms the need for much increased urgent action from around the world if society stands a chance of limiting warming to 1.5 ºC.

https://science.feedback.org/review/global-warming-fire-suppression-practices-boost-wildfires-us-west-correctly-reported-the-atlantic-robinson-meyer/

2

The Atlantic, by Robinson Meyer, on 2017-09-07.

"Has Climate Change Intensified 2017’s Western Wildfires?"

This story in The Atlantic describes the conditions that have contributed to this year’s widespread wildfires in the western United States, including the influence of a changing climate. Scientists who reviewed the story found that it was an accurate summary of the factors involved in this fire season—warm temperatures as well as past fire-suppression practices that have increased the density of fuel available for fires to burn.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Logan Berner Assistant Research Professor, Northern Arizona University: The article provides an excellent summary of how rising air temperatures are leading to drier conditions and more fire activity among forests in parts of the western United States. The article is strengthened by including multiple interviews with scientists who have produced seminal studies of fire-climate interactions in this region. One minor error is that the “paper published in Science last year” was actually published in 2006, not 2016, yet this oversight detracts little from the overall accuracy of the article. Ben Poulter Research Scientist, NASA: The article highlights clearly the challenges that scientists and managers face in disentangling how changes in ignitions, fuel loading, past-management legacies and climate interact to start and sustain fires. William Anderegg Associate Professor, University of Utah: The article is well-supported by the peer-reviewed literature. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Featured Annotations: The statements quoted below are from the article; comments and replies are from the reviewers. “How did a wet Western winter lead to a sky-choking summer?The answer lies in the summer’s record-breaking heat, say wildfire experts. Days of near-100-degree-Fahrenheit temperatures cooked the Mountain West in early July, and a scorching heat wave lingered over the Pacific Northwest in early August.” Logan Berner Assistant Research Professor, Northern Arizona University: Exceptionally high summer air temperatures undoubtedly contributed to the extensive forest fire activity that occurred during the summer of 2017 in the western United States. Forest flammability is affected by both winter snowfall and seasonal rain, as well as by spring and summer air temperatures that regulate the timing of snowmelt and how much water the atmosphere will suck out of the forest.“the total area burned in the western United States over the past 33 years was double the size it would have been without any human-caused warming.” Anthony LeRoy Westerling Associate Professor, University of California, Merced: I would say: “the total area burned in the western United States over the past 33 years was at least double the size it would have been without any human-caused warming.” “Fires have not only been increasing in size due to climate change. In the early 20th century, state and federal governments began aggressively fighting wildfires and trying to keep them as small as possible. This has caused denser and more fire-prone forests than the long-term average for the West, which has led to more massive and uncontrollable fires.” Logan Berner Assistant Research Professor, Northern Arizona University: This statement should have included a citation and also noted that the influence of fire suppression on subsequent fire activity varies with the frequency of historical fires. The century of fire suppression has potentially increased fuel accumulation in dry forests that historically experienced very frequent fires (e.g. every 5-20 years). On the other hand, fire suppression has likely had far less of an impact on wetter forests, such as those in coastal Oregon and Washington, that historically went centuries without fire.

https://science.feedback.org/review/incorrect-claim-global-warming-mostly-natural-based-on-study-that-cant-support-conclusion-jennifer-marohasy-john-abbot/

Incorrect

The Spectator, Jennifer Marohasy, 2017-08-21

Most of the recent warming could be natural

Unsupported: The methods of this study, published in the journal GeoResJ, do not provide evidence for its claim that humans are not the primary cause of global warming. Cherry-Picking: The study relied on several local records of past climate rather than a global compilation, and failed to account for the important difference between local and global temperature change and variability.

Natural changes in climate cannot explain recent global warming, while the human-caused increase in greenhouse gas concentrations matches the observed warming well. The analysis contained in this paper—which includes important mistakes—does not demonstrate that natural cycles are responsible for modern climate change.

Most of the recent warming could be natural [...] we suggest that at most, the contribution of industrialisation to warming over the twentieth century would be in the order of 0.2°C. [...] we also calculate an Equilibrium Climate Sensitivity (ECS) of 0.6°C

Chris Brierley Senior Lecturer, University College London: I consider this claim to be incorrect and unsubstantiated. The authors are right in stating that “The uptake of machine learning, and specifically ANNs, in climate science has generally been slow compared to many other fields.” The assertion that “This may in part be due to the heavy investment in physical models, particularly GCMs.” is not right though—rather it arises from a widespread acknowledgment within the discipline of meteorology that physically-based models have greater predictive power than purely statistical ones (which is why all weather forecasters use general circulation models). The authors here clearly know that humans have increased CO2 levels and that would be expected to alter the energy budget of the climate. There are certain situations where the statistical assumptions going into the sort of Artificial Neural Network built by the authors are just not met. The introduction of a new factor (us and our emissions) not present in the training data (the climate proxy record) is clearly one such situation. Rather than using their data to claim that recent global warming was natural, it would instead be more appropriate to say that detecting the signal of anthropogenic climate change is hard given the noise of natural variability, especially at local scales. This topic is often referred to as the “emergence” of the climate signal. Ed Hawkins has a nice blogpost on it here. In the maps on that webpage, it shows that climate change (the signal) would not have emerged from natural variations (the noise) until after the end of the proxy records used by Abbot & Marohasy. I would also have expected the authors to have performed an actual calculation of Equilibrium Climate Sensitivity. They appear to assume (a) the climate system responds instantaneously, (b) CO2 levels have been 100 ppm higher throughout the past 150 years – instead of rising roughly exponentially (c) humans did not impact the climate in other ways—e.g. aerosol emissions, other greenhouse gases, and land use change. All those assumptions are not valid. Patrick Brown Assistant Professor, San Jose State University: 1) We know the basic physics of global temperature so it’s incorrect to assume global temperatures follow “natural cycle” sine curves. Temperature is essentially a measure of energy and global temperature changes when an energy imbalance is imposed on the Earth system. This known physics helps us understand global climate changes of the past. The Abbot and Marohasy paper acts as if we don’t know this physics and must rely on curve-fitting (signal analysis) to understand temperature changes. Abbot and Marohasy’s method assumes that temperature changes over centuries move up and down in accordance with sine-curves, with no physical explanation for why temperatures should do that. Earth’s temperature does not know what a sine curve is and there is no reason to think that Earth’s temperature should follow magic “natural cycle” sine-curves. To be more specific, we know that a large portion of the cooling during the Little Ice Age was caused by negative radiative-forcing from volcanic eruptions: Figure – Composite temperature reconstructions with climate forcings and previous hemisphere-scale reconstructions. Vertical red bands indicate volcanic-solar downturns that explain a large portion of the cooling during the “Little Ice Age”.Source:Pages 2K (2013) So temperatures went down, not because they were following some magic “natural cycle” sine-curve but because they were pushed downward from Earth experiencing a negative energy imbalance due to volcanic aerosols. Since the current climate change is also being caused by an energy imbalance, scientists can use this information from the past to assess precisely how sensitive temperature is to energy imbalances. So climate changes of the past do not in any way undermine the attribution of current climate change to anthropogenic greenhouse gasses. The bottom line is that assuming temperature changes blindly follow mathematical functions like sine curves, without considering the known physical reasons for why temperatures change, is scientific nonsense. 2) Their ‘natural cycle’ statistical model cannot predict the recent spike in temperatures. As Gavin Schmidt has pointed out (illustrated here), Abbot and Marohasy mistakenly think that the year 1965 is actually the year 2000. This totally undermines their central claim that their statistical model, based on assumed “natural cycle” sine-curves, can explain recent warming. Shaun Lovejoy Professor, McGill University: It is highly significant for this study that all of the six proxies chosen had proxy temperatures that declined or were at best constant after 1975, underscoring a combination of proxy problems (e.g. dendrochronology) and the unrepresentativeness of the proxy choices. In the “Northern Hemisphere composite” (from [one] Icelandic lake), the temperature even decreases by a whopping 0.3 °C since 1980—yet from the authors’ description, one could be forgiven for thinking that this behaviour was somehow representative of the actual Northern Hemisphere temperature. Rather than using the original data, the authors scanned the published graphs and used very low resolution versions of the data. From their graphs, it would seem that the resolutions they obtain are between 20 – 50 years (more on this later). This is a shame since in many cases the original data had annual resolution. These geographic and temporal resolution issues are underlined since they turn out to be fundamental. For example, a dozen or so globally or hemispherically representative pre-industrial multiproxies exist, each based on hundreds or thousands of individual proxies—not just 6. They show that the pre-industrial global temperature series has decadal scale oscillations that are close to ±0.1 °C and this is supported by pre-1900 instrumental data. The true decadal global scale fluctuations are thus about ten times smaller than the local series analyzed by Abbot and Marohasy. The most important point is that they committed the common but fundamental error of scale, in time, but here, mostly in space. As the authors themselves comment on multiple occasions, on multidecadal time scales the proxy temperatures fluctuate about ±1 °C. This is normal since each proxy only represents the behavior of a tiny region. When the IPCC claims that the industrial epoch temperature has increased by about 1 °C, they are referring to the globally averaged surface air temperature, and this (as we have mentioned) varies only by about ±0.1 °C over decadal time scales. The authors—being apparently unfamiliar with climate science—seem to have missed the factor of 10 discrepancy. And the explanation for the difference is simple. In the pre-industrial epoch, local temperatures varied by ±1 °C over decadal scales, but the variations over different parts of the world tended to cancel out, hence the far lower global variability. However—and this can indeed be seen by careful superposition, even of the authors’ hand picked proxies—in the last century there is a tendency for the local fluctuations to fluctuate together (and upwards!) rather than tending to cancel each other out. That’s the essence of global warming—it’s not local, it’s global! [Read more]

https://science.feedback.org/review/climate-change-likely-helped-increase-hurricane-harveys-rainfall-early-say-exactly-much/

Mostly correct

The Atlantic, Robinson Meyer, 2017-08-27

[climate scientists] say that aspects of the case of Hurricane Harvey suggest global warming is making a bad situation worse.

Correct but...: Warming sea surface temperatures provide more energy for tropical cyclones and a warmer atmosphere holds more water vapor. While rainfall do show a relationship to climate change, Hurricanes' impact are also influenced by other factors –like blocking events, vertical wind shear, urban planning…– that are not or not easily connected to climate change.

Extreme rain events, including those accompanying Tropical Cyclones, are intensifying as the world warms. However, a dedicated study would be needed to quantify how much more rain Hurricane Harvey generated due to climate change.

[climate scientists] say that aspects of the case of Hurricane Harvey—and the recent history of tropical cyclones worldwide—suggest global warming is making a bad situation worse.

Andrew King Research fellow, University of Melbourne: This is a reasonable statement. As tropical cyclones are such complex events— the confluence of many factors coming together—it is difficult to estimate the climate change role in such events. However, it is likely that human-caused climate change has worsened aspects of this event as described later in the article. Dan Chavas Assistant Professor, Purdue University: It is true that for a Harvey-like event—a storm at this location in East Texas that is nearly stationary—global warming likely increases the total rainfall. But we do not know whether global warming makes it more likely for a Harvey-like events to occur in the first place. Risk combines both of these probabilities. In combination, then, it is difficult to say whether there is a climate change effect on this type of flood risk. A number of articles that quote scientists—or were written by scientists—have been published on this topic already. Here are some of the statements published elsewhere that explain the effect of climate change and other factors on the severity of the damage done by Harvey.1) On sea surface temperatures and the effect of warmer atmosphere on moisture content and rain Michael Mann Professor of Meteorology, PennState University: [S]ea surface temperatures in the region have risen about 0.5 °C (close to 1 °F) over the past few decades from roughly 30 °C (86 °F) to 30.5 °C (87 °F), which contributed to the very warm sea surface temperatures (30.5-31 °C, or 87-88 °F). There is a simple thermodynamic relationship known as the Clausius-Clapeyron equation that tells us there is a roughly 3% increase in average atmospheric moisture content for each 0.5 °C of warming. Sea surface temperatures in the area where Harvey intensified were 0.5-1 °C warmer than current-day average temperatures, which translates to 1-1.5 °C warmer than “average” temperatures a few decades ago. That means 3-5% more moisture in the atmosphere. (Source) Adam Sobel Professor, Columbia University: [T]he recurrence of 100- and 500-year floods every few years is unlikely to be entirely accidental. Though Houston developers, many state and local officials, and the occupant of the White House don’t want to hear it, it’s likely that human-induced climate change has played a role in the increasing frequency of these events. There is more water vapor in a warmer atmosphere, and many other extreme rainfall events both nationwide and worldwide (including, very nearby, the Louisiana flood of just a year ago) have been shown to be amplified as a consequence. (Source) Andrew King Research fellow, University of Melbourne: While it’s hard to pin the blame for Hurricane Harvey directly on climate change, we can say this: human-caused climate change has enhanced some of the impacts of the storm. We know that climate change is enhancing extreme rainfall. As the atmosphere is getting warmer it can hold more moisture (roughly 7% more for every 1°C rise in temperature). This means that when we get the right circumstances for very extreme rainfall to occur, climate change is likely to make these events even worse than they would have been otherwise. Without a full analysis it is hard to put exact numbers on this effect, but on a basic level, wetter skies mean more intense rain. (Source) Suzana Camargo,Professor, Columbia University: and Adam SobelProfessor, Columbia University Tropical cyclones are similar to other truly heavy rain events in that they are very efficient in turning that water vapor into rain. While there is much uncertainty about how tropical cyclones should change with global warming, that they should produce more rain is perhaps one of the most confident predictions of current science on this topic. The only debate is how much heavier the rains should get with each degree of warming, and to what extent this effect is already present in observed storms today. (Source) 2) On the high pressure system that kept Harvey in place Michael Mann Professor of Meteorology, PennState University: [P]art of what has made Harvey such a devastating storm is the way it has stalled right near the coast, continuing to pummel Houston and surrounding regions with a seemingly endless deluge which will likely top out at nearly 4 feet of rainfall over a several days-long period before it is done. The stalling is due to very weak prevailing winds which are failing to steer the storm off to sea, allowing it to spin around and wobble back and forth like a top with no direction. This pattern, in turn, is associated with a greatly expanded subtropical high pressure system over much of the U.S. right now, with the jet stream pushed well to the north. This pattern of subtropical expansion is predicted in model simulations of human-caused climate change. (Source) Suzana Camargo,Professor, Columbia University: and Adam SobelProfessor, Columbia University In this case, one of the most important causes of the disaster is Harvey’s slow motion. That in turn is a consequence of the specific weather situation, in which the storm is caught between two high-pressure systems and the jet stream is too far away to the north to pull it away. In other words, it has just been sitting and dumping its huge quantities of rain in the same area for days, rather than spreading it out over a long track as a typical storm would. There are some ideas in the scientific literature that suggest that global warming may make this situation more probable. However, these ideas are still speculative and not widely agreed upon by scientists. (Source) Friederike Otto Deputy Director Environmental Change Institute, University of Oxford: It is very appropriate to highlight that this is the kind of event we expect to see more of in a warming world. However, to apply this argument directly and attribute (and quantify) the impacts from Harvey itself to human-induced climate change, neglects that climate change is not just about warming. In a changing climate, two effects come together: not only does the atmosphere warm up (thermodynamic effect) but the atmospheric circulation, which determine where, when, and how weather systems develop, can change as well (dynamic effect). Changes in the atmospheric circulation can increase the thermodynamic effect (as we saw during floods Louisiana in 2016) or act in the opposite direction to the thermodynamic effect, leading to locally decreasing the risk of extreme rainfall or canceling the effect of the warming alone (examples here). Hence, while it is very likely that climate changes played a role in the intensity of the rainfall, it is far from straightforward in practice to quantify this role. […]If we thus want to know whether Harvey is a “harbinger” for the future of Houston, the attribution question addressing the overall likelihood of a hurricane like Harvey to occur, which includes many variables other than temperature and sea level rise that interact, needs to be answered by carefully estimating the likelihood of such hurricanes developing in a warming world as well as how much rain they bring. It is a question scientists now can answer, but it requires a dedicated study. Furthermore, attributing the flooding and damages to climate change add more complexity. The answer does not depend on the weather alone but on the land surface, local hydrology, management, … and ultimately who and what is in harm’s way. (Source) Tim Palmer, Professor, University of Oxford: What has made Harvey so disastrous for Texas is the fact that it has stalled and the circulation patterns are continuously feeding moist air from the Gulf of Mexico up over Texas. So perhaps the single most important question for attributing Harvey to climate change is whether such stationary hurricanes will become more commonplace in the future. This is a question about possible changes in circulation and hence dynamics, rather than changes in the moistness and warmth of the air per se and hence thermodynamics. Unfortunately it is not a question that can be answered with a great deal of confidence from current-generation global climate models since their spatial resolution is typically inadequate to address such regional matters with any degree of reliability. (Source) 3) On the human factors that help determine the damage caused a particular storm Ilan Kelman, University College London: The hurricane is just a storm, it is not the disaster. The disaster is the fact that Houston population has increased by 40% since 1990. The disaster is the fact that many people were too poor to afford insurance or evacuate. Climate change did not make people build along a vulnerable coastline so the disaster itself is our choice and is not linked to climate change. (Source) Suzana Camargo,Professor, Columbia University: and Adam SobelProfessor, Columbia University [G]iven a metro area of 6.5 million people that basically sits in a paved floodplain, crossed by bayous, creeks, and rivers, and the same meteorological situation, we would be seeing a very major disaster even without any human influence on climate. But any extra rainfall due to warming just increases the human and financial toll of the disaster. (Source) Andrew King Research fellow, University of Melbourne: There are other factors that are making this storm worse than others in terms of its impact. Houston is the second-fastest growing city in the US, and the fourth most populous overall. As the region’s population grows, more and more of southern Texas is being paved with impermeable surfaces. This means that when there is extreme rainfall the water takes longer to drain away, prolonging and intensifying the floods. Hurricane Harvey is likely to end up being one of the most costly disasters in US history. It is also likely that climate change and population growth in the region have worsened the effects of this major storm. (Source)

https://science.feedback.org/review/atlantic-accurately-explores-climate-context-tropical-storm-harvey-robinson-meyer/

1.5

The Atlantic, by Robinson Meyer, on 2017-08-27.

"Did Climate Change Intensify Hurricane Harvey?"

This article in The Atlantic attempted to investigate what can be said about the relationship between Tropical Storm Harvey and climate change. Harvey’s record rainfall totals around Houston, Texas are partly the result of how long it has persisted in the same location, making it an unusual storm. Scientists who reviewed the article indicated that it provides an accurate summary of how tropical cyclones are expected to change due to global warming, as well as what aspects of Harvey do not have clearly understood relationships with climate change.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Andrew King Research fellow, University of Melbourne: This article provides an excellent overview of Hurricane Harvey with good explanations of why it’s so extreme and how climate change may have contributed to this event. Karthik Balaguru Scientist, Pacific Northwest National Laboratory: Overall I think it’s a well written article that captures the essence of our understanding that under climate change storms will likely bring more rainfall. In the case of Harvey, all we can say is that it is consistent with those ideas. But we cannot say that it is the direct consequence of climate change. Dan Chavas Assistant Professor, Purdue University: One must be careful not to assume that warmer waters automatically make all aspects of extreme weather worse. Though for a given storm we do expect rainfall rates to increase at a warmer sea surface temperature, how storm size, regional counts, and track characteristics (e.g. the likelihood that a storm will become nearly stationary as was the case with Harvey) will change in a warmer world are much less well understood. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from the article; comments and replies are from the reviewers. Tropical cyclones and extreme rain events are expected to intensify as the world warms, but the complex meteorological conditions that produced Harvey also depend on processes with an uncertain relationship to climate change. “But [climate scientists] say that aspects of the case of Hurricane Harvey—and the recent history of tropical cyclones worldwide—suggest global warming is making a bad situation worse.” Andrew King Research fellow, University of Melbourne: This is a reasonable statement. As tropical cyclones are such complex events— the confluence of many factors coming together—it is difficult to estimate the climate change role in such events. However, it is likely that human-caused climate change has worsened aspects of this event as described later in the article. Dan Chavas Assistant Professor, Purdue University: It is true that for a Harvey-like event—a storm at this location in East Texas that is nearly stationary—global warming likely increases the total rainfall. But we do not know whether global warming makes it more likely for a Harvey-like events to occur in the first place. Risk combines both of these probabilities. In combination, then, it is difficult to say whether there is a climate change effect on this type of flood risk. For more details on what can be said about the influence of climate change on Hurricane Harvey, read this claim review post. “The human contribution can be up to 30 percent or so of the total rainfall coming out of the storm” Karthik Balaguru Scientist, Pacific Northwest National Laboratory: Climate change doesn’t cause events like this, but probably makes them worse by making storms (which are strong to begin with) more intense and enhancing rainfall in that process. I don’t think anyone can say with confidence that climate change has made tropical cyclones worse. There’s too much natural variability (Pacific Decadal Oscillation, Atlantic Multidecadal Oscillation, etc.) and the sample size of intense hurricanes is small. It is consistent with what’s predicted for the future, though. However, I’m not exactly sure where the “30 percent” number comes from for the human contribution to rainfall. For every one degree increase in sea surface temperature, the saturation vapor pressure increases by about 7% based on the “Clausius-Clapeyron” equation. There’s also an assumption that hurricanes will likely get stronger because of climate change, so perhaps the stronger winds will also increase evaporation. Andrew King Research fellow, University of Melbourne: A reference here would have been useful as it’s unclear exactly where this number comes from. We know that human-caused climate change can increase both the moisture content of the atmosphere, as described by the Clausius-Clapeyron relation, and the energetics of the storm, as there is increased latent heat release. Both of these climate change-influenced drivers have the potential to cause increased precipitation. Dan Chavas Assistant Professor, Purdue University: Again, it is true that in a warmer world we expect the rain rate to increase significantly. (I am not sure about the 30% specifically, but that doesn’t matter.) Thus, given the existence of a Harvey-like storm—a storm at this location in East Texas that is nearly stationary—global warming likely significantly increases the total rainfall. However, there is a second probability to account for: how likely is it for a Harvey-like event to occur in the first place? This is a much more difficult probability to assess and we do not know how climate change affects it. Risk combines these two probabilities. As a result, it is difficult to say whether there is a climate change effect on the likelihood of a flood event of this magnitude. “The tropical storm, feeding off this unusual warmth, was able to progress from a tropical depression to a category-four hurricane in roughly 48 hours.” Andrew King Research fellow, University of Melbourne: This storm was quite remarkable in its intensification. It does seem likely that the warmth of the surface and sub-surface waters, primarily linked to variability but also with a small climate change contribution, enhanced the storm.

https://science.feedback.org/review/new-york-times-accurately-assesses-the-state-of-alaskan-permafrost-henry-fountain/

1.6

The New York Times, by Henry Fountain, on 2017-08-23.

"Alaska's Permafrost is Thawing"

This story in the New York Times looks at the thawing trend of permafrost (permanently frozen soil and sediment) in Alaska as the region warms due to climate change, and the potential for this landscape to be an additional source of greenhouse gases in the future, which would further amplify global warming. Scientists who reviewed the article found that it accurately represented current research on the region, which shows that Alaska’s area of permafrost is shrinking as more and more ground thaws. This destabilizes the land surface, damaging buildings and infrastructure, and allows frozen organic matter to decay. Given the uncertainty in future projections of greenhouse gases released by thawing permafrost, however, providing more information than just the upper end of the range could help readers understand this feedback more clearly. This is part of a series of reviews of 2017’s most popular climate stories on social media.GUEST COMMENTS: Miriam Jones, Research Geologist, United States Geological Survey: This article accurately represents the state of our knowledge on permafrost thaw and carbon dynamics, and it conveys why this is an important issue to study for the future state of our planet. I take slight issue with the description of the age of the permafrost (“centuries”); the author could have gone bolder and said centuries to many millennia, since permafrost carbon age can range from a few centuries to as old or older than the last glacial maximum (20,000 years ago). Permafrost thaw is described as gradual and “top down”, which is definitely true, but it’s not the only way it thaws. It can thaw laterally, from below, and much faster than gradually.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Ben Poulter Research Scientist, NASA: The observations being made by Woods Hole Research Center researchers on the thawing of permafrost is consistent with other ecosystem changes taking place in the region that are related to climate change. These include increased growing season length, decreasing arctic sea ice, disruptions to infrastructure, and changes in wildlife populations. The main uncertainty (which this work contributes to reducing) is related to how strong the permafrost-climate feedback is, and how continued climate change will destabilize the high-arctic frozen soils. Andrew MacDougall Assistant Professor, St. Francis Xavier University: Overall the article does a good job of summarizing the potential effects of the permafrost carbon feedback to climate change. However, the article highlights the very upper-end of the estimated strength of the feedback instead of giving the most likely values or ranges. Figure – Simulated warming contribution from permafrost carbon feedback for 4 scenarios of future human greenhouse gas emissions. SourceMacDougall et al (2012) MacDougall et al (2012) Significant contribution to climate warming from the permafrost carbon feedback, Nature Geoscience Charles Koven Staff Scientist, Lawrence Berkeley National Lab: The article is accurate in its descriptions of the physical and ecological processes that are behind permafrost changes. It also does a good job of getting across the nature of the work of actual scientists working in the field, what they are doing and why they are doing it. Jeff Chanton Professor, Florida State University: I work in this field, and I think they have it right. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time.

https://science.feedback.org/review/extreme-weather-events-clearly-becoming-common-contrast-lord-lawsons-claim/

Inaccurate

BBC, Nigel Lawson, 2017-08-10

The IPCC, the Intergovernmental Panel on Climate Change, which is sort of the voice of the consensus, concedes that there has been no increase in extreme weather events.

Misrepresents source: The 2013 IPCC report identifies some extreme events for which trends are unclear, but it also identifies certain types of weather extremes that research shows are clearly increasing, like heat waves and intense rainfall.

Globally, there has been a clear increase in certain weather extremes including heat waves and intense rainfall events.

[Al Gore] said that there had been a growing increase, which had been continuing, in the extreme weather events. There hasn’t been. All the experts say there haven’t been. The IPCC, the Intergovernmental Panel on Climate Change, which is sort of the voice of the consensus, concedes that there has been no increase in extreme weather events. Extreme weather events have always happened. They come and go. And some kinds of extreme weather events of a particular time increase, whereas others, like tropical storms, diminish…

Andreas Prein Project Scientist, National Center for Atmospheric Research: This is a false statement since the IPCC AR5 even states in its summary for policy makers that “Human influence has been detected … in changes in some climate extremes”. In this report it is also stated that: “It is now very likely that human influence has contributed to observed global scale changes in the frequency and intensity of daily temperature extremes since the mid-20th century, and likely that human influence has more than doubled the probability of occurrence of heat waves in some locations” and “It is virtually certain that there will be more frequent hot and fewer cold temperature extremes over most land areas on daily and seasonal timescales as global mean temperatures increase. It is very likely that heat waves will occur with a higher frequency and duration.” Since the publication of the IPCC AR5 many studies where published on the detection and attribution of man made impacts on climate extremes. An example which shows the human influence on precipitation extremes is Fischer and Knutti (2015)*. Fischer and Knutti (2015) Anthropogenic contribution to global occurrence of heavy-precipitation and high-temperature extremes, Nature Climate Change Ken Caldeira Senior Scientist, Carnegie Institution for Science: A good place to go for IPCC conclusions related to extreme events is the Summary: for Policy Makers of the 2012 IPCC “SREX”1 and 2014 Synthesis reports2. The 2014 Synthesis Report concludes: “Changes in many extreme weather and climate events have been observed since about 1950. Some of these changes have been linked to human influences, including a decrease in cold temperature extremes, an increase in warm temperature extremes, an increase in extreme high sea levels and an increase in the number of heavy precipitation events in a number of regions…. It is very likely that the number of cold days and nights has decreased and the number of warm days and nights has increased on the global scale. It is likely that the frequency of heat waves has increased in large parts of Europe, Asia and Australia. It is very likely that human influence has contributed to the observed global scale changes in the frequency and intensity of daily temperature extremes since the mid-20th century. It is likely that human influence has more than doubled the probability of occurrence of heat waves in some locations.” Thus, Lord Lawson’s statement is false. On the other hand, in the Synthesis Report, the IPCC also states: “There is low confidence that anthropogenic climate change has affected the frequency and magnitude of fluvial floods on a global scale. … There is low confidence in observed global-scale trends in droughts, due to lack of direct observations, dependencies of inferred trends on the choice of the definition for drought, and due to geographical inconsistencies in drought trends. … There is low confidence that long-term changes in tropical cyclone activity are robust, and there is low confidence in the attribution of global changes to any particular cause. However, it is virtually certain that intense tropical cyclone activity has increased in the North Atlantic since 1970.” Thus, there are many extreme events occurring which likely bear little or no relationship to climate change, and this may be what Lord Lawson was attempting to point out. While true, this does not mean that climate change is not contributing to increases in some kinds of extreme events. 1- IPCC (2012) Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation 2- IPCC (2014) Climate Change 2014: Synthesis Report Jeremy Fyke Postdoctoral researcher, Los Alamos National Laboratory: Lord Lawson’s blanket claim that the frequency of extreme events has not increased is wrong. Due to overall warming, for example, it is very clear in observations that the frequency and severity of extreme heat events is increasing, and that this increase would not occur in the absence of anthropogenic forcing. Twila Moon Research Scientist, University of Colorado, Boulder: This statement is not true. The IPCC issued a 2012 report on “Managing the risks of extreme events and disasters to advance climate change adaptation”1. Even within the Summary for Policymakers, the report lists the evidence of changes in extreme weather and climate events. Changes are different depending on the location (e.g. more intense and longer droughts in southern Europe and West Africa, while this is not true in North American and northwestern Australia), but changes in extremes have been documented across the globe (with low to high confidence depending on the type of event and location). The IPCC AR5 Summary for Policymakers2 states: “Changes in many extreme weather and climate events have been observed since about 1950 (see Table SPM.1 for details). It is very likely that the number of cold days and nights has decreased and the number of warm days and nights has increased on the global scale. It is likely that the frequency of heat waves has increased in large parts of Europe, Asia and Australia. There are likely more land regions where the number of heavy precipitation events has increased than where it has decreased. The frequency or intensity of heavy precipitation events has likely increased in North America and Europe. In other continents, confidence in changes in heavy precipitation events is at most medium.” It also notes: “There has been further strengthening of the evidence for human influence on temperature extremes since the SREX. It is now very likely that human influence has contributed to observed global scale changes in the frequency and intensity of daily temperature extremes since the mid-20th century, and likely that human influence has more than doubled the probability of occurrence of heat waves in some locations.” Note that it’s possible to cherry pick types of extreme events and locations to argue that there is no evidence. Also, perhaps even more important than whether extremes have already changed is that there is high certainty of changes in a number of important extremes over the coming decades. 1- IPCC (2012) Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation 2- IPCC (2013) Climate Change 2013: The Physical Science Basis Adam Sobel Professor, Columbia University: The statement, though often repeated, is patently false. Clear increases have been documented in the frequencies and intensities of heat waves and extreme precipitation events. There are other kinds of events for which there are no trends, and then others for which it is not clear whether there are trends, because natural variability is difficult to separate from long-term trends in short historical records. And indeed predictions about what global warming should do to extreme events vary from one kind of event to the next. But the observed increases in heat waves and extreme rain events are right in line with what is expected based on the predictions. And, because of the confounding effect of natural variability, there are some changes that we shouldn’t expect to see clearly yet, even though we are pretty confident that we will eventually. These include increasing intensity of tropical cyclones, and increasing occurrence of hydrological droughts and wildfires in many places. Daniel Swain Climate Scientist, University of California, Los Angeles: The specific claim here–that the IPCC scientific reviews find no increase in extremes–is incorrect, as is the broader implication that there is no observational evidence for increasing meteorological extremes. The IPCC Special Report on Managing the Risk of Extreme Events (SREX) directly contradicts the former claim, while a rapidly growing body of scientific research points toward a clear increase in certain types of extreme weather events–especially heat waves, droughts, and heavy downpours (e.g., Diffenbaugh et al. 2017)*. While it is certainly true that some of these extreme events would have occurred naturally (and that not all event types are increasing in all regions), human-caused global warming is exerting an increasingly substantial influence on the risk of global temperature and precipitation extremes. Diffenbaugh et al. (2017)Quantifying the influence of global warming on unprecedented extreme climate events.Proceedings of the National Academy of Sciences Ed Hawkins Principal Research Fellow, National Centre for Atmospheric Science: The statement about the IPCC is incorrect. The 5th Assessment Report of the IPCC actually states in the Summary for Policymakers that: “Changes in many extreme weather and climate events have been observed since about 1950.” It goes on to give specific examples: “It is very likely that the number of cold days and nights has decreased and the number of warm days and nights has increased on the global scale. It is likely that the frequency of heat waves has increased in large parts of Europe, Asia and Australia. There are likely more land regions where the number of heavy precipitation events has increased than where it has decreased. The frequency or intensity of heavy precipitation events has likely increased in North America and Europe.” The statement that “extreme weather events have always happened” is misleading. Yes, extreme weather events have always happened, but many of them show long-term trends in frequency and/or intensity, as the IPCC AR5 states. For other types of extreme event we would not have expected to clearly see a long-term change given the warming to date, but would expect to see significant changes at higher warming levels. Richard Betts Professor, Met Office Hadley Centre & University of Exeter: This statement is not true. The IPCC does not say that “there has been no increase in extreme weather events”. In the IPCC’s Fifth Assessment Report, in the Physical Science volume, the very first table of the summary document gives a comprehensive, careful and nuanced assessment of different types of extreme weather events and whether there has been an increase in them. The IPCC’s conclusion is that for some types of extreme weather event, such as hot days, heatwaves and heavy precipitation, there have been increases (with varying levels of confidence and likelihood attached to these conclusions, ranging from “very likely” to “medium confidence. For other types of extreme weather events, such as drought and tropical cyclones, there is low confidence in a global-scale trend but nevertheless increases in some more localized regions are likely to have occurred. Andrew King Research fellow, University of Melbourne: Using the vague term “extreme weather”, Lord Lawson argues there has been no increase in such events. He then makes a specific reference to tropical storms for which it is true that while we are seeing signs of change in some characteristics we are not seeing an increase in their overall number. However, if we look at other types of extreme weather that cause greater numbers of fatalities, such as heatwaves, then Lord Lawson is incorrect. Heatwaves impact human health[1], and can compound the effects of drought and famine. The intensity, frequency and duration of heatwaves around the world is on the rise due to human-caused climate change[2]. Figure – Warm spell and heatwave trends in the number of days participating in an event, in which conditions persist for at least three consecutive days. Trends are for the period 1950–2011. Units are percentage of days per season/decade. Hatching represents where trends are significant at the 5% level, and grey indicates areas where there are insufficient observations for this study. Source:Perkins et al (2012) 1- Perkins et al (2012)Increasing frequency, intensity and duration of observed global heatwaves and warm spells. Geophysical Research Letters 2- Mitchell et al (2016) Attributing human mortality during extreme heat waves to anthropogenic climate change.Environmental Research Letters

https://science.feedback.org/review/lord-lawson-falsely-claims-global-temperatures-declined-last-decade/

Inaccurate

BBC, Nigel Lawson, 2017-08-10

according, again, to the official figures—during this past 10 years, if anything, mean global temperature, average world temperature, has slightly declined

Factually inaccurate: Global temperature datasets show rising—not falling—temperatures over the last ten years.

Global temperature has continued to rise during the last decade. The three warmest years on record are 2014, 2015, and 2016.

And as for the temperature itself, it is striking, [Gore] made his previous film 10 years ago and—according, again, to the official figures—during this past 10 years, if anything, mean global temperature, average world temperature, has slightly declined.

UPDATE (18 Aug 2017): The Global Warming Policy Forum, of which Lord Lawson is the chairman, tweeted that Lord Lawson’s statement was based on a chart that is “erroneous”. Read more Andreas Prein Project Scientist, National Center for Atmospheric Research: I am wondering which official figures Lord Lawson speaks about since the year with the hottest global mean temperature is currently 2016, the second hottest is 2015, and third is 2014 according to data sets from NASA, the Climatic Research Unit, and the National Oceanic and Atmospheric Administration. In fact, according to these data sets the last 10 years saw some of the most rapid global mean temperature increases in observed history. Below is a figure that shows the data from NASA. Ken Caldeira Senior Scientist, Carnegie Institution for Science: Multiple independent analyses have concluded that years 2014, 2015 and 2016 were the hottest annual global mean temperatures ever observed by modern humans. It would be mathematically impossible for the hottest years to appear at the end of 10 years of declining temperature. An example of such temperature records is available here. It is obvious and clearly demonstrable that this statement made by Lord Lawson is false. Jeremy Fyke Postdoctoral researcher, Los Alamos National Laboratory: This claim is false and not supported by any official figures. Average world temperature reached a record high in 2016. Twila Moon Research Scientist, University of Colorado, Boulder: It’s not clear why Nigel Lawson would think that he should only mention 10 years of global temperature data. We are now able to look at trends that are much longer than 10 years. In fact, when looking at climate trends it is especially useful to look at 20+ year records. Many different groups are studying global temperature and there is a clear consensus that the Earth has been warming over the last several decades. It is critical to remember that short-term fluctuations in the record are expected, but do not negate the long-term march of increasing global temperatures. This is true regardless of the trend over the last 10 years. Furthermore, the scientific evidence actually points towards warmer temperatures over the last decade*. NASA keeps a nice up-to-date global temperature graph in it’s Vital Signs. Rahmstorf et al (2017) Global temperature evolution: recent trends and some pitfalls, Environmental Research Letters Victor Venema Scientist, University of Bonn, Germany: It would be hard to be more wrong. The graph below shows the “official” figures. Source: Climate.gov MetOffice statistician Doug McNeal kindly made a figure to show the last 10 years more clearly. Source Ten years is very short to judge whether the climate is changing. But in the figure you can see that the three hottest years on record occurred in 2014, 2015 and 2016. 2017 is on track to be among the hottest again. Source Adam Sobel Professor, Columbia University: The statement about the last 10 years is patently false. Each of the the last three years—2014, 2015, and 2016—has been the warmest in history. It might have been true, in a narrow sense, if it had been made a few years ago; but even then it would have been highly misleading, since the predictions about global warming apply to long-term averages, not individual decades. Each decade since the mid-20th century has been warmer than the one before, without exception. Ed Hawkins Principal Research Fellow, National Centre for Atmospheric Science: This statement by Lord Lawson is entirely untrue. Over the last 10 years, every surface global temperature dataset shows a clear rise in temperatures with 2014, 2015 & 2016 being the warmest years on record. The latest estimates of global atmospheric temperature, as measured by satellites, also show a warming trend over the past 10 years. Richard Betts Professor, Met Office Hadley Centre & University of Exeter: This statement is not true. The official figures do not show that the global mean temperature “has slightly declined”. In fact they show the opposite – global mean temperature has increased during the past 10 years. The last 3 years were warmer than the previous 7 and indeed were the warmest in record, and this year is also shaping up to be nearly as warm (probably not quite as warm as last year since the influence of the El Nino has passed, but still a very warm year). This is very clearly seen in the Met Office dataset, which happens to be shown prominently on the websites for Lord Lawson’s organisations, the Global Warming Policy Foundation and the Global Warming Policy Forum – so his claim is contradicted by information that headlines his own websites. UPDATE (18 Aug 2017): Here is a screenshot of the statement posted on the Global Warming Policy Forum’s Twitter account:

https://science.feedback.org/review/forbes-article-accurately-describes-research-atlantic-ocean-circulation-weakening-headline-goes-farther-trevor-nace/

1

Forbes, by Trevor Nace, on 2017-08-03.

"Global Ocean Circulation Appears To Be Collapsing Due To A Warming Planet"

This article at Forbes describes a study on the possible influence of Arctic sea ice loss on recent changes to a key portion of ocean circulation in the Atlantic Ocean. This Atlantic Meridional Overturning Circulation (AMOC) transports heat around the North Atlantic, but could be slowing down as a result of climate change, with consequences for regional temperatures in Europe and eastern North America. Scientists who reviewed the article found that it accurately summarized research on the topic of the AMOC. However, the headline used stronger wording than the article, stating that “global ocean circulation appears to be collapsing due to a warming planet”. That is misleading, as this research is analyzing a weakening of the circulation pattern, but not something as extreme as a “collapse”.See all the scientists’ annotations in context If the link does not work due to Forbes’ landing page, addHypothesisto your browser and switch it on when the article pagehas loaded. This is part of a series of reviews of 2017’s most popular climate stories on social media.GUEST COMMENTS: Stefan Rahmstorf Professor, Potsdam University: I find the article is a very accurate summary of the state of science, with the exception of the word “collapsing” in the headline (which may well have been not the author’s choice). Changing this word to “weakening” would have left me with nothing to complain about.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Dan Jones Physical Oceanographer, British Antarctic Survey: This is an accurate, concise summary of the slowdown of the AMOC and its possible future states. There are a couple of minor issues—specifically, one of the links goes to an irrelevant article, and it would be useful to have a couple more citations to the scientific literature. The title is possibly a little overstated—I might instead say that the AMOC is at risk of collapsing in a warming world. Alek Petty Postdoctoral associate, NASA Goddard Space Flight Center: I think the article did a pretty good job of summarizing the main findings of this paper (and other recent studies on this theme), while adding some appropriate disclaimers. The main issue I had was with the headline. The weakening of the Atlantic Meridional Overturning Circulation isn’t exactly a collapse of the global ocean circulation, and the author makes a point of the high uncertainty that remains regarding the significance of this result towards the end of the story. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Featured Annotations: The statements quoted below are from the article; comments and replies are from the reviewers. “Global Ocean Circulation Appears To Be Collapsing Due To A Warming Planet” Dan Jones Physical Oceanographer, British Antarctic Survey: I’m a little hesitant about the title. The slowdown of the Atlantic Meridional Overturning Circulation is not the same thing as the “collapse of global ocean circulation”. It might be more accurate to say that the AMOC is at risk of collapsing in a warming world. Also, it’s worth noting that although we understand that there is a connection between AMOC and the amount of carbon dioxide in the atmosphere, the mechanisms involved in this connection are still under investigation. “Evidence is growing that the comparatively cold zone within the Northern Atlantic could be due to a slowdown of this global ocean water circulation.” Dan Jones Physical Oceanographer, British Antarctic Survey: For example, this study: Rahmstorf et al (2015) Exceptional twentieth-century slowdown in Atlantic Ocean overturning circulation, Nature Climate Change “While geologists have studied events in the past similar to what appears to be happening today, scientists are largely unsure of what lies ahead.” Stefan Rahmstorf Professor, Potsdam University: A very brief but correct reference to two issues: 1) We know the AMOC has collapsed several times in the past 100,000 years in the so-called Heinrich events, and 2) we cannot predict its future response to greenhouse warming very well because it is a highly non-linear system. “Scientists have long known about the anomalous ‘warming hole‘ in the North Atlantic Ocean, an area immune to warming of Earth’s oceans.” Dan Jones Physical Oceanographer, British Antarctic Survey: This link for “warming hole” appears to go to an irrelevant article. Here are two relevant studies on the “warming hole”: Drijfhout et al (2012) Is a Decline of AMOC Causing the Warming Hole above the North Atlantic in Observed and Modeled Warming Patterns?, Journal of Climate Rahmstorf et al (2015) Exceptional twentieth-century slowdown in Atlantic Ocean overturning circulation, Nature Climate Change

https://science.feedback.org/review/wall-street-journal-op-ed-economic-consequences-climate-change-found-naive-scientists-david-henderson-john-cochrane/

-1.5

The Wall Street Journal, by David Henderson, John Cochrane, on 2017-07-30.

"Climate Change Isn’t the End of the World"

This Wall Street Journal commentary by David Henderson and John Cochrane argues that the world would be better off adapting to climate change than eliminating the greenhouse gas emissions that cause warming. Scientists who reviewed this article found that it does so by ignoring most climate impacts apart from estimates of Gross Domestic Product change, by using only the most optimistic estimates of this economic loss, and by focusing on adaptation possibilities in high-income nations like the United States. Climate change could have a much larger economic impact, along with impacts on the spread of human disease, food security, extreme weather, and marine ecosystems, for example.See all the scientists’ annotations in context REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Aaron Bernstein Associate Director of the Center for Health and the Global Environment, Boston Children’s Hospital, Harvard: Although many claims in this op-ed don’t mesh with reality, the most concerning delusion presented is that the health costs of climate change are both known and manageable. Legitimate economic analyses have put the costs of climate change at 2100 to GDP at several percent to more than 20%[1], with the variability largely due to different discount rates. Simply put, the more you care about children, the more expensive climate change becomes. Even these higher damage estimates may fail to capture the full costs of extreme events over time, as Martin Weitzman’s work has shown. But there’s another, and more difficult, rub. What if we don’t understand the full consequences of greenhouse gas emissions? Consider ocean acidification, which is a direct consequence of higher atmospheric carbon dioxide concentrations. The higher acid content in the world’s oceans has already begun to interfere with marine life, including fish reproduction. Research has just begun to explore the reverberations of ocean acidification to human nutrition (and consequently risk of migration and conflict). Economists do not include these massive externalities in their estimates because they have yet to be quantified. If we underestimate climate damages, we won’t simply have a costly externality kicked down the road for our children to deal with. We might not have a viable planet, and without a second planet in the wings, betting the viability of the world on a few uncertain economic analyses seems like an act of utter folly. We must, of course, make trade-offs in where we put our money but doing so based on the face value of current economic evaluations—especially those based on GDP which is generally regarded as a poor measure of economic health—gives catastrophic error too great a chance. A better approach would be to focus on implementing carbon prices that will limit greenhouse gas emissions to levels that will prevent levels of warming that the scientific community and most nations on earth have deemed potentially disastrous for human civilization. 1- Burke et al (2015)Global non-linear effect of temperature on economic production. Nature David Easterling Chief of the Scientific Services Division, NOAA's National Climatic Data Center: This is a very simplistic, almost naive op-ed on climate change impacts. Some assertions such as the one about CO2 being good for plants demonstrates that the authors do not know or understand how increasing CO2 is good or bad for plants, they are just repeating something they heard. The idea that Miami is going to build a dike like Rotterdam is almost laughable. Of course climate change is not the only risk to society, but it is the biggest environmental risk. And most large buildings (e.g. Empire State Building) are not rebuilt every 50 years, only smaller, more expendable ones are. Frank Vöhringer Dr. rer. pol, Scientist, Ecole Polytechnique Fédérale de Lausanne (EPFL): The article plays down impacts of climate change that most studies consider to be highly important: e.g. the death toll of heat waves, hazards to coastlines, costs and friction of migration and other adaptation. While it is true that climate change is not the only risk our society faces, economic studies suggest that the risks of climate change are important, especially in certain economic segments (e.g. agriculture, health) and for low income countries with low capacity for adaptation. The article fails to mention that hazards and distributive issues of climate change increase all the other risks that the authors itemize, “nuclear explosions, a world war, global pandemics, crop failures and civil chaos”, even if it is not yet clear to what extent. Verena Schoepf Research Associate, University of Amsterdam: The authors seem unaware of many consequences of climate change, particularly related to the ocean. The increase in ocean acidity and temperature, due to uptake of atmospheric CO2, will have tremendous consequences for many marine organisms and thus ultimately humans via sea level rise, impacts on weather and climate, food security, etc. Wolfgang Cramer Professor, Directeur de Recherche, Mediterranean Institute for Biodiversity and Ecology (IMBE): This article argues that policies concerning climate change need to differentiate between different objectives and instruments and also says that, in some sectors such as built infrastructure, adaptation may be less costly than what is conventionally assumed. While this may be true as a general statement (and nothing is new about it), the article creates confusion rather than clarification by focusing only on the few sectors where, in a “North American world” unaware of any poor countries, adaptation can be achieved at manageable cost. The article does not ask the question how other sectors besides the construction sector might fare under significant warming, nor how low-income people (inside or outside North America) would be affected. It also avoids speaking about the major economic and socio-political disruptions of the world being caused by warming and sea-level rise in developing countries. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Featured Annotations: The statements quoted below are from the article; comments and replies are from the reviewers. “Carbon dioxide hurts nobody’s health. It’s good for plants. Climate change need not endanger anyone” Aaron Bernstein Associate Director of the Center for Health and the Global Environment, Boston Children’s Hospital, Harvard: By this logic, the authors would gladly drink water endlessly, in the belief that as a harmless—even potentially beneficial—substance, doing so could never hurt them. Unfortunately for them they’d die from having so wrecked their bodies’ chemistry. Carbon dioxide, like water, isn’t acutely toxic to people (though it does appear to slow our brains down). But the amount of carbon dioxide in the atmosphere is already 50% higher than at any point in modern human existence. The harms that result from this change to the planets chemistry are many and well described in, among other places, the U.S. National Climate Assessment. “Healthy societies do not fall apart over slow, widely predicted, relatively small economic adjustments of the sort painted by climate analysis. Societies do fall apart from war, disease or chaos. Climate policy must compete with other long-term threats for always-scarce resources.” Aaron Bernstein Associate Director of the Center for Health and the Global Environment, Boston Children’s Hospital, Harvard: To suggest that climate change does not bear (or has little bearing) upon war, disease, and chaos represents either an exceedingly narrow and optimistic view of available peer reviewed research on the influence of climate change on these outcomes or ignorance. The extraordinary threat that climate change already poses to national security was outlined by the U.S. Defense Department in 2015. Research on climate change and infectious disease risks suggests that it either directly (through changes in mosquito population distributions) or indirectly (through forcing mass migrations) will augment risks of pandemics.

https://science.feedback.org/review/2017-track-among-hottest-year-recorded-scientists-not-surprised-thinkprogress-article-suggests-joe-romm/

1

Think Progress, by Joe Romm, on 2017-07-19.

"2017 is so unexpectedly warm it is freaking out climate scientists"

ThinkProgress published a brief but influential article commenting on record warm global temperature over the first half of 2017. The scientists who have reviewed the article confirm it accurately reports that 2017 is on track to being one of the warmest years on record. Reviewers note this wasn’t as unexpected as the article states, but the fact that 2017 global surface temperatures are that high is a clear reminder that global warming has not stopped or slowed down.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: While generally accurate, the article may overstate how unusual 2017 is shaping up to be. It is very unlikely to set a new temperature record in any of the different global surface temperature datasets (NOAA, NASA, Hadley, Berkeley Earth), and is likely to either be the second or third warmest on record. If 2017 temperatures end up comparable to or slightly below 2015, a year where the El Niño contribution was not that large, 2017 temperatures will be quite warm but “extremely remarkable” might be overstating the case a bit. However, even if temperatures end up being below 2015, the year 2017 will likely be a bit warmer than we’d naively expect simply based on the past warming trend: Victor Venema Scientist, University of Bonn, Germany: The large variety of comical claims that scientists are surprised 2017 will be warm is somewhat annoying, (the Earth is warming, every year will normally be among the warmest recorded) but the facts are otherwise right. Richard Betts Professor, Met Office Hadley Centre & University of Exeter: This article is factually correct in terms of the presentation of the data, but the claim that this is “a surprise to climate scientists” is not correct. The article seems to have been written without awareness of some important and relevant climate science. In December 2016, climate scientists at the UK’s Met Office Hadley Centre predicted that 2017 would be “another very warm year for global temperatures” – see MetOffice news release. I’m giving this a rating of 0 (neutral) because although the scientific content of the article is correct, the headline that this is “unexpected” is incorrect. Eric Guilyardi CNRS Research Director, Université Pierre et Marie Curie & Professor, University of Reading: This article rightly explains that El Niño events, which see the tropical Pacific – a quarter of the planet’s surface – warm by a few degrees celsius, boost the global surface temperature by a few tenth of a degree. So having a year without El Niño being 1°C warmer than the pre-industrial period adds to the evidence that the planet is warming at a pace that is not due to natural variability. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Featured Annotations: The statements quoted below are from the article; comments and replies are from the reviewers. “’Extremely remarkable’ 2017 heads toward record for hottest year without an El Niño episode.” Victor Venema Scientist, University of Bonn, Germany: At the moment, it is more likely than not that 2017 will become the second warmest year of the instrumental period. The warmest was 2016 with El Niño. So this claim is correct. “So it’s been a surprise to climate scientists that 2017 has been so remarkably warm — because the last El Niño ended a year ago.” Victor Venema Scientist, University of Bonn, Germany: 2016 would most likely also have been a record warm year without El Niño. Given the long-term warming trend due to global warming, it was to be expected that 2017 would also be warm. Richard Betts Professor, Met Office Hadley Centre & University of Exeter: The claim that this is “a surprise to climate scientists” is not correct. In December 2016, climate scientists at the UK’s Met Office Hadley Centre predicted that 2017 would be “another very warm year for global temperatures”. 2017 was forecast to be among the warmest on record, but not as warm as 2016, so what is happening is actually consistent with the prediction. “that is a sign the underlying global warming trend is stronger than ever.” Victor Venema Scientist, University of Bonn, Germany: The rate of warming has been about the same since 1980. The warming is only exceptionally strong if you were deceived by people claiming that global warming had/has stopped. “The latest NOAA report is “a reminder that climate change has not, despite the insistence of climate contrarians ‘paused’ or even slowed down,” Mann said..” Victor Venema Scientist, University of Bonn, Germany: Right. “2017 is so unexpectedly warm it is freaking out climate scientists” Richard Betts Professor, Met Office Hadley Centre & University of Exeter: 2017 is not “unexpectedly warm” nor is it “freaking out” climate scientists, because they predicted this! Victor Venema Scientist, University of Bonn, Germany: No, we are not freaked out.

https://science.feedback.org/review/scientists-explain-what-new-york-magazine-article-on-the-uninhabitable-earth-gets-wrong-david-wallace-wells/

-0.7

New York Magazine, by David Wallace-Wells, on 2017-07-09.

"The Uninhabitable Earth"

New York Magazine published an article by David Wallace-Wells detailing the potential impacts of climate change if no action is taken to reduce greenhouse gas emissions. Much of the article explores “worst case” scenarios of change in the climate system and the resulting impacts on human populations. Scientists reviewed the article to determine whether the descriptions of those scenarios accurately reflect the state of scientific knowledge. The New York Magazine article has triggered a number of responses debating the merits of the decision to focus on worst case scenarios, but our review simply addresses the scientific accuracy of the article. The reviewers found that some statements in this complex article do misrepresent research on the topic, and some others lack the necessary context to be clearly understood by the reader. Many other explanations in the article are correct, but readers are likely left with an overall conclusion that is exaggerated compared to our best scientific understanding.See all the scientists’ annotations in context This is part of a series of reviews of 2017’s most popular climate stories on social media.UPDATE (15 July 2017):New York Magazine has published an annotated version of its article indicating sourcing, which also incorporates several edits based on scientists’ comments.Read more Update (13 July 2017): The analysis has been updated to include several comments received just after the time of publication. The main conclusion of the analysis is unchanged. GUEST COMMENTS: Michael Mann Professor of Meteorology, PennState University: The article paints an overly bleak picture by overstating some of the science. It exaggerates for example, the near-term threat of climate “feedbacks” involving the release of frozen methane (the science on this is much more nuanced and doesn’t support the notion of a game-changing, planet-melting methane bomb. It is unclear that much of this frozen methane can be readily mobilized by projected warming). Also, I was struck by erroneous statements like this one referencing “satellite data showing the globe warming, since 1998, more than twice as fast as scientists had thought.” That’s just not true. The study in question simply showed that one particular satellite temperature dataset that had tended to show *less* warming that the other datasets, has now been brought in line with the other temperature data after some problems with that dataset were dealt with. Ironically, I am a co-author of a recent article in the journal Nature Geoscience (see e.g. this piece), using that very same new, corrected, satellite dataset, that shows that past climate model simulations slightly **over-predicted** the actual warming during the first decade of the 21st century, likely because of a mis-specification of natural factors like solar variations and volcanic eruptions. Once these are accounted for, the models and observations are pretty much in line—the warming of the globe is pretty much progressing AS models predicted… which is bad enough. The evidence that climate change is a serious problem that we must contend with now, is overwhelming on its own. There is no need to overstate the evidence, particularly when it feeds a paralyzing narrative of doom and hopelessness.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Richard Betts Professor, Met Office Hadley Centre & University of Exeter: While it is clear that ongoing warming of the global climate would eventually have very severe consequences, the concept of the Earth becoming uninhabitable within anywhere near the timescales suggested in the article is pure hyperbole. The author has clearly done very extensive research and addresses a number of climate threats that are indeed major issues, but generally the narrative ramps up the threat to go beyond the level that is supported by science. Daniel Swain Climate Scientist, University of California, Los Angeles: This is an unusual piece in that it accurately describes some of the most dire consequences of unabated global warming but focuses almost exclusively on worst case scenarios. In doing so, it provides a compelling narrative of what could happen in the future, but does not accurately characterize the likelihood of particular outcomes relative to what is justifiable based upon existing scientific evidence. Charles Koven Staff Scientist, Lawrence Berkeley National Lab: The article, while it does thoughtfully discuss some serious implications of climate change, also goes beyond the evidence in a number of instances of its exploration of worst-case scenarios. Alexis Berg Research Associate, Harvard University: This article focuses on the high-end scenario for global warming—high emissions and/or high climate sensitivity, high impacts. It selects recent research that highlights these outcomes. I am sympathetic to the author’s efforts to raise awareness about such scenarios, including impacts that are not always well discussed, and agree that we tend to focus too much on median outcomes. Nevertheless, I think the article would have gained from a more explicit acknowledgement that this particular focus is the goal of the article, as well as a from an explicit discussion (even if only qualitative) of the probabilities associated with these scenarios. Absent that, I am afraid the article, as such, feels misleading, or at least confusing for the general public. In addition, the article contains a number of claims that are factually wrong, and a number of claims that are, to my knowledge, not substantiated by research. I was also concerned by the implied claim that this article, being written after interviews with many climate scientists, somehow reflects scientists’ true opinion about global warming. I don’t believe it does. What this article suggest to me is that we, as as community of scientists and science journalists, need to find a better way to more accurately discuss climate change projections and to convey the associated risks to the public. Peter Neff Assistant Research Professor, University of Minnesota: In what seems an ode to new journalism, the author takes significant literary license to leverage information grounded in truth and paint an apocalyptic picture of extreme future scenarios possibly driven by anthropogenic climate change. Ambiguous references to studies, events and examples severely impairs credibility, as does a complete disregard for nuance. Christopher Colose Research Scientist, SciSpace LLC, NASA Goddard Institute for Space Studies: There are many arguments in this article at the interface of climate instability, socio-political disruption, and general global security. They are, however, clumsily wrapped together and doesn’t reflect well the actual risk posed by climate change. A general comment concerning the climate response to future carbon emissions—one of the emergent insights from decades of research is that linearity is too powerful of a tool to be abandoned lightly. In this context, it is better to think of future warming as smoothly monotonic in our total carbon emissions rather than behaving erratically due to significant non-linearities in the system. There is no evidence that a very abrupt methane source(s) will be readily mobilized into the atmosphere. Such scenarios are not supported by process studies, it is not emerging observationally, and is not borne out paleoclimatically (particularly in the mid-Holocene or Eemian interglacial, where high latitude summers were hotter than today). A small trickle of CH4 release is very plausible, but methane becomes converted to CO2 pretty quickly in Earth’s atmosphere, and there’s already some 200 times more CO2 in the air than CH4. These types of carbon cycle feedbacks will likely give the direct anthropogenic carbon input just a small boost in the near future. Similarly, it’s not obvious that there are any significantly missing feedbacks that should radically alter the linear perspective (certainly, any under-representation of surface albedo feedbacks in current models are unlikely to be the difference maker, since the polar regions make up a very small percentage of the globe and the surface contribution to the planetary albedo is somewhat masked by clouds). A Younger Dryas event today would likely be quite disruptive (the global mean temperature changes were quite modest, but the extratropical temperature re-organizations would still be significant); however, the processes leading to an event like this are pretty unique to a glacial climate undergoing melting, and is unlikely to occur in a warming world during our present interglacial. Actual numbers are important here. The global temperature increase could indeed reach 4-5 degrees by 2100, if humans don’t do anything to our emissions, and beyond this patches of uninhabitable areas (for humans) could start to open up in the tropics, due to heat stress limits imposed by the evaporative limits of our body. Indeed, a world 5+ degrees warmer is a big cause for alarm, even if the world takes a linear path to that mark. The world also does not end in 2100, and while it is tempting to think of later dates as “very far off,” it is worth reminding ourselves that we would live on a different planet had people of the Viking era industrialized and emitted carbon uncontrollably. Nonetheless, the near future climatic fate of New York probably looks more like the climate of South Carolina or Georgia than something from a Mad Max movie. This is still an important basis for concern given that the socio-political infrastructure that exists around the world is biased toward the modern climate. Many of the nightmare scenarios in this article, such as no more food, unbreathable air, poisoned oceans, perpetual warfare, etc. are simply ridiculous, although food security is indeed an issue at stake (see David Battisti’s comments). A “business-as-usual” climate in 1-2 centuries still looks markedly different than the current one, but there’s no reason yet to think much of the world will become uninhabitable or look like a science fiction novel. Victor Venema Scientist, University of Bonn, Germany: We are taking the climate system out of known territories. There will be many surprises and they are what worry me the most. Uncertainty is not our friend and that makes it very hard to say which worst case scenarios are unrealistic. The bigger the stakes the smaller the acceptable risks. A risk someone may be willing to take personally will be larger than the risk one takes with a community, a country or civilization. In that respect it is good that the article explores what surprises may be in store and talks about scenarios that are not likely, but a large part of the total risk. However, unfortunately often statements are inaccurate, wrong or are missing important context. These inaccuracies tend to exaggerate the risks of climate change. Charles Koven Staff Scientist, Lawrence Berkeley National Lab: The article, while it does thoughtfully discuss some serious implications of climate change, also goes beyond the evidence in a number of instances of its exploration of worst-case scenarios. Benjamin Horton Professor, Earth Observatory of Singapore: Most statements in the article are based on peer-reviewed literature. Pierre Friedlingstein Professor, University of Exeter: The article is very alarmist, making very strong statements with very little (if any) support. Implying that climate scientists support the article, which I find hard to believe. Such article does not help at all. It’s just too easy to prove it wrong and hence imply that the entire climate change issue is exaggerated. David Archer Professor, University of Chicago: I do not disagree with the tone of the article in the way that most folks here seem to, and I think it does a service to highlight recent results and ideas throughout the scientific community. However there are inaccurate statements, like about satellite warming since 1998, unsupported conclusions or implications (about past mass extinctions, air chemistry, maybe arctic methane). But I feel that the overall thrust of the article is not wrong, wildly misleading, or out of bounds of the discussion we should be having about climate change. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from the article; comments and replies are from the reviewers. 1. The article attempts to describe a worst case scenario for future warming. “The Uninhabitable Earth” Daniel Swain Climate Scientist, University of California, Los Angeles: The title itself is hyperbolic—there’s not really a plausible climate change scenario in which the Earth becomes truly uninhabitable. That’s not to downplay the very real and very large threat to human lives, economies, infrastructure, ecosystems, and species—and the author does a good job cataloging many of these later in the piece. But taken literally, the title implies a future bleaker than is warranted by existing scientific evidence. “Famine, economic collapse, a sun that cooks us: What climate change could wreak — sooner than you think.” David Archer Professor, University of Chicago: This is well-researched and on target. Unfortunately. “Venus, which was once a very Earth-like planet with plenty of life-supporting water before runaway climate change rapidly transformed it into an arid and uninhabitable sphere enveloped in an unbreathable gas” Richard Betts Professor, Met Office Hadley Centre & University of Exeter: There’s been a lot written about this recently, following the BBC’s publicising of Stephen Hawking’s remarks on it. I don’t think it is accurate to say that Venus was “once a very Earth-like planet” and hence imply that the runaway greenhouse effect could happen here. For one thing, Venus is much closer to the sun. A runaway greenhouse effect on Earth is not thought to be a plausible threat. Ted Letcher Research Scientist, Cold Regions Research and Engineering Lab: My expertise is not in exoplanetary climate, but it is not a definitively accepted “fact” that Venus was once habitable. There is still considerable debate regarding the past habitability of Venus (see links below). Therefore, this statement (which appears to imply that Venus’s climate trajectory is foreshadowing for Earth’s) comes off way too strong. Way et al (2016) Was Venus the first habitable world of our solar system?, Geophysical Research Letters Chassefière et al (2012) The evolution of Venus: Present state of knowledge and future exploration, Planetary and Space Science “parts of the Earth will likely become close to uninhabitable” Alexis Berg Research Associate, Harvard University: I am not sure how one defines habitability. Paucity of resources (e.g., water, vegetation) does not necessarily make a region uninhabitable. So I think that strictly speaking, the author is referring here to studies showing that the combination of heat+humidity may exceed a threshold for human survival some part of the year in already-very-hot-an-humid parts of Southwest Asia (around the Gulf of Persia) by the end of the century1. To my knowledge this kind of result hasn’t been shown for other regions, so in that context, the sentence “parts of”, while technically correct, may imply more than has been established. Note, however, that even without exceeding survival limits, humid heat increases would have impacts on outdoor activities2. Pal and Eltahir (2016) Future temperature in southwest Asia projected to exceed a threshold for human adaptability, Nature Climate Change Dunne et al (2013) Reductions in labour capacity from heat stress under climate warming, Nature Climate Change “there are alarming stories every day, like last month’s satellite data showing the globe warming, since 1998, more than twice as fast as scientists had thought” Carl Mears Senior Research Scientist, Remote Sensing Systems (RSS): This sentence is true for RSS data, but it’s somewhat misleading due to lack of context. If you look at the two most recent versions of the RSS data and compute linear trends Jan 1998-Dec 2016, you find that the new version has a trend value for this period of about 2.6 times larger than the previous version. But, it is good to remember that 1998 is a favorite starting point for those that seek to minimize the perceived threat of global warming. This preference is because 1998 is a relative maximum in global temperature (due to a large ENSO event), and thus trends that start in Jan 1998 are smaller than trends that start in other, nearby years. This means that when the change in trends between datasets is reported as a multiplicative effect, the change appears quite large. However, if one calculated the trends for Jan 1999-Dec 2016 instead, the trends increases by a factor of about 1.6, not 2.6, only a 60% increase. Of course this is still a pretty large increase. The sentence also ignores the other sources of lower-tropospheric satellite data. The newer version of the UAH (Version 6.0) data shows less warming than the previous version. Also, the radiosonde datasets show more warming over this period that any of the satellite datasets (except maybe UAH V5.6), and have done so for years. Alexis Berg Research Associate, Harvard University: If anything, satellite measurements of lower atmospheric temperatures (which is what the author is talking about here, not near-surface, 2-meter temperature), show slightly less warming than predicted by models, a discrepancy that is a topic of ongoing research*. Santer et al (2017) Causes of differences in model and satellite tropospheric warming rates, Nature Geoscience Victor Venema Scientist, University of Bonn, Germany: I would like to add that this “twice as fast” is just for a cherry-picked period. That is about as bad as mitigation sceptics claiming that global warming has stopped by cherry picking a specific period. The real message was that satellite upper air warming estimates are unreliable (still are), but seem to confirm what we know from the surface warming. This story was thus not alarming. If anything is was good news, it reduces uncertainties and as this uninhabitable-article already suggests: uncertainty is not our friend. “Or the news from Antarctica this past May, when a crack in an ice shelf grew 11 miles in six days, then kept going; the break now has just three miles to go — by the time you read this, it may already have met the open water, where it will drop into the sea one of the biggest icebergs ever, a process known poetically as ‘calving.’” Peter Neff Assistant Research Professor, University of Minnesota: Although a particularly dramatic and well-observed example of how floating ice shelves calve icebergs into the ocean, there is little evidence that the crack in the Larsen C ice shelf is directly related to climate change. At best this is subject to considerable debate, as it is difficult to directly connect particular atmospheric and oceanic mechanisms to the cracking of this single, albeit large, proto-iceberg. For a very measured treatment of this topic, see the Guardian article by Professor Helen Fricker of Scripps Institute of Oceanography. Having now just calved an iceberg as of July 12, it is good to hear from the most experience experts how concerning this event is. A really great simple summary is provided by David Vaughan, Director of Science for the British Antarctic Survey, who has worked on the Antarctic Peninsula and studied regional ice shelves for decades. “But no matter how well-informed you are, you are surely not alarmed enough” Daniel Swain Climate Scientist, University of California, Los Angeles: It is quantitatively true—and often under-appreciated—that the likelihood of a “worse than expected” climate future is actually higher than a “better than expected” one. That is: the distribution of climate outcomes is not symmetrical, and as others have previously pointed out, “uncertainty is not our friend“. “This article is the result of dozens of interviews and exchanges with climatologists and researchers in related fields” Alexis Berg Research Associate, Harvard University: This sentence implies, somehow, that the scientific content of this article comes from these scientists, or that they agree with it. I don’t believe that this is entirely the case—e.g. see Michael Mann’s comments—and, the author should have mentioned that as a caveat here. “and we will need to have invented technologies to extract, annually, twice as much carbon from the atmosphere as the entire planet’s plants now do” Charles Koven Staff Scientist, Lawrence Berkeley National Lab: Its unclear in this statement, about the relative amount of negative emissions needed versus the amount of carbon extracted by plants, whether the author means the total amount of photosynthesis by plants (which would be a false statement) or the total difference between photosynthesis, respiration, and disturbance (which would be a true statement). Plants photosynthesize about 120 petagrams of carbon per year, whereas the net land sink is more like 2-3 petagrams of carbon per year. It is the latter number that is comparable in magnitude to the negative emissions technologies required. “at least four feet of sea-level rise and possibly ten by the end of the century” Benjamin Horton Professor, Earth Observatory of Singapore: This statement is supported by peer-reviewed literature. 20th and 21st century rates of relative sea-level rise varied from -4 mm/yr to 3 mm/yr, and are dwarfed by potential future rates of 21st century rise, which under high forcing and unfavorable ice sheet dynamics could exceed 2 meters (i.e., a century-average rate of 20 mm/yr) in many locations. “Most people talk as if Miami and Bangladesh still have a chance of surviving; most of the scientists I spoke with assume we’ll lose them within the century, even if we stop burning fossil fuel in the next decade.” Richard Betts Professor, Met Office Hadley Centre & University of Exeter: These places are clearly at high risk of more frequent coastal flooding, but suggesting that we will “lose them within a century” is an exaggeration. Although there are substantial threats of flooding events, much of the country is not actually at risk of permanent indundation this century. Scientists and policymakers in Bangladesh are well aware of the threat of rising sea levels and are actively involved in research and planning on this, and this includes a strong focus on adaptation (as well as on making the case for reducing the threat through mitigation). They point to the example of the Netherlands to show that low-lying countries can adapt and even reclaim land from the sea. Of course this won’t be possible everywhere, especially in wilderness areas such as the Sundarbans which would be impacted by such measures themselves, but talk of the entire country “not surviving” is not a fair reflection of the scientific analysis. 2. Some types of extreme weather conditions, like heatwaves, are expected to increase with future warming. The response of other specific types of weather, such as tornadoes, remains uncertain. “This past winter, a string of days 60 and 70 degrees warmer than normal baked the North Pole” Victor Venema Scientist, University of Bonn, Germany: Regions with open water will stay relatively warm due to the relatively warm water. As soon as ice limits heat flows from the ocean to the atmosphere it can get very cold. Also, in general variability is much stronger in the Arctic—what sounds like a really big warm anomaly to an innocent reader in the USA is thus exceptional, but less so than the numbers suggest. That is context a reader would need to know. Steffensen et al (2008) High-Resolution Greenland Ice Core Data Show Abrupt Climate Change Happens in Few Years, Science “Even if we meet the Paris goals of two degrees warming, cities like Karachi and Kolkata will become close to uninhabitable, annually encountering deadly heat waves like those that crippled them in 2015. At four degrees, the deadly European heat wave of 2003, which killed as many as 2,000 people a day, will be a normal summer. At six[…] summer labor of any kind would become impossible in the lower Mississippi Valley, and everybody in the country east of the Rockies would be under more heat stress than anyone, anywhere, in the world today[…].” Alexis Berg Research Associate, Harvard University: “At two degrees… at four… at six” What is missing here is a discussion of the probabilities of each target, depending on emission scenarios, etc… It’s fine to discuss high-end scenarios, but mentioning probabilities would add context—without deterring from discussing the extreme risks associated, I believe. In general, the language in this paragraph is dire, but, in my opinion, this is an underappreciated consequence of global warming, and the author does well to highlight it. It’s difficult to extrapolate future impacts from one-time events: the 2003 heatwave killed that many people in Europe because it was so far out from the usual distribution, and populations were poorly prepared. In a warmer future, preparedness and reactivity would arguably be improved, so impacts could be reduced. Kristie Ebi Professor, University of Washington: The article highlights worst case projections of the intensity of heatwaves, but not of their frequency. Projections indicate return periods of high-mortality heatwaves will shorten over the century and, in some cases, the length of these high-mortality heatwaves will increase. That does not mean these events will occur every day during a summer. In many regions, this means a high-mortality heatwave could occurcould approachbecoming an annual event instead of rarely. Further, the projections do not take into account that increased heat-related hazardsare only one factor that influences future risks. The other factors are the extent of exposure, the vulnerability of the exposed population, and the capacity of individuals and communities to prepare for and manage heatwaves. There is growing literature that sensitivity to heatwaves has declined over recent decades, presumably because of some degree of acclimatization to ever higher temperatures, increasing access to air conditioning and cooling centers, better understanding and communication of the risks of high ambient temperatures, and changing infrastructure to reduce urban heat islands. Recent projections using different approaches that take these changes into accountshow that taking these factors into account decreases the magnitude of risks. “unprecedented droughts nearly everywhere food is today produced” Richard Betts Professor, Met Office Hadley Centre & University of Exeter: Actually, overall the general projection is for the world to be wetter on average, with increasing drought in some regions but decreases in others, and increased annual rainfall in many places. The projections are extremely uncertain though, so while it is probably possible to cherry-pick model simulations that suggest increased drought in almost any region (and hence argue, probably fairly, that most places do have some increased risk of drought) these would not be expected to happen concurrently everywhere. A scenario with increased drought in one region would generally see a decrease elsewhere. “a constant swarm of out-of-control typhoons and tornadoes and floods and droughts” Alexis Berg Research Associate, Harvard University: Not to nitpick—we don’t really know what a +6 °C world would look like in detail—but the connection between tornadoes and warming is unclear, at least in the observable record. Daniel Swain Climate Scientist, University of California, Los Angeles: While there is still some uncertainty regarding the response of tropical cyclones (i.e. typhoons and hurricanes) to global warming, there is now evidence that frequency in many ocean basins may actually decrease, but maximum intensity will likely increase. There is indeed evidence that the frequency and intensity of floods/droughts is increasing over much of the globe*, and will continue to do so as the climate warms. This is not necessarily true universally–there will still be quite a bit of spatial and temporal diversity in the response of precipitation extremes to global warming, even in a six-degree-warmer world. But in general, it’s true that there will be dramatically more flood and drought events on a global basis with multiple degrees of warming. Diffenbaugh et al (2017) Quantifying the influence of global warming on unprecedented extreme climate events, PNAS “The strongest hurricanes will come more often” Daniel Swain Climate Scientist, University of California, Los Angeles: This is a plausible claim, especially in a “six degree warmer world”. “tornadoes will grow longer and wider” Daniel Swain Climate Scientist, University of California, Los Angeles: I’m not aware of any scientific evidence for this claim. There has been some work investigating global warming and atmospheric environments conducive to severe thunderstorms (and tornadoes), but to my knowledge there are no peer-reviewed studies that investigate changes in either “length” or “width” of tornadoes. In general, the net effect of climate change upon tornado activity/intensity remains uncertain1, with evidence for increasingly favorable atmospheric environments for tornado formation in some regions2. 1- Tippett et al (2016) More tornadoes in the most extreme U.S. tornado outbreaks, Science 2- Diffenbaugh et al (2013) Robust increases in severe thunderstorm environments in response to greenhouse forcing, PNAS “hail rocks will quadruple in size” Daniel Swain Climate Scientist, University of California, Los Angeles: There is indeed evidence that maximum hail size in severe thunderstorms may increase with global warming (even while overall hail frequency may decrease). Brimelow et al (2017) The changing hail threat over North America in response to anthropogenic climate change, Nature Climate Change Diffenbaugh et al (2013) Robust increases in severe thunderstorm environments in response to greenhouse forcing, PNAS 3. Feedbacks like the release of greenhouse gases from warming landscapes can amplify warming trends, but these processes appear overstated in the article. “In other words, we have, trapped in Arctic permafrost, twice as much carbon as is currently wrecking the atmosphere of the planet, all of it scheduled to be released at a date that keeps getting moved up, partially in the form of a gas that multiplies its warming power 86 times over.” Charles Koven Staff Scientist, Lawrence Berkeley National Lab: Most work on studying the dynamics of greenhouse gas balance in degrading permafrost systems, both as based on field measurements and as represented in ecosystem models for making climate feedback projections, seems to point to methane release being a relatively minor pathway for permafrost carbon to be released to the atmosphere, at least for terrestrial permafrost sources (which comprise most of the carbon mentioned here). It is true that terrestrial permafrost systems emit methane, but most of that methane is from recently photosynthesized carbon rather than older permafrost sources, and most of the carbon released from the older permafrost sources is released as either carbon dioxide or dissolved organic carbon rather than methane. So, while uncertainty on this issue remains high, and permafrost thaw is a potentially strong feedback process, this feedback seems likely to be dominated by carbon dioxide rather than methane. A specifically misleading thing about these numbers, which are a metric called “global warming potential”, is that their units are based on the mass of the gas. Since the question here is whether a given atom of carbon will be emitted to the atmosphere contained within either a molecule of carbon dioxide or a molecule of methane, you have to take into account the fact that the molecule of carbon dioxide is much heavier, because of the two oxygen atoms it picks up in the transformation to that gas, versus the four hydrogen atoms it would acquire in becoming methane. What this means in practice is that you have to divide the global warming potential by the ratio of the weight of the molecules, which is 44/16 or 2.75. So strictly speaking, the 34 and 86 ought to read 12 and 31. This is a separate issue from the timescale one that others point out, and which further makes this comparison misleading. David Archer Professor, University of Chicago: It would be wrong to say, as I often read in the popular press, that all or most of the frozen permafrost carbon will come out as methane, or that Arctic methane will have much impact on climate evolution in the near future. But this article doesn’t exactly say that. Carbon released from permafrost that eventually reaches the atmosphere as CO2 could significantly add to the “long tail” climate impacts from CO2. And this is a much more certain outcome than from methane. The factor of 86 however is totally misleading about the impact of methane vs. CO2. This is an instantaneous impact on radiative forcing (a high-end one at that), and doesn’t reflect the longevity of CO2 (long enough to melt ice sheets) vs. methane (which, emitted now, will mostly be CO2 by the time of peak temperature, say, optimistically, 2050). Vasilii Petrenko, Assistant Professor, University of Rochester: This is incorrect. First, to the best of my knowledge, there currently is not a strong consensus about whether thawing permafrost areas would be a net carbon sink or source. If the only process is that the permafrost carbon is respired by microbes and released to the atmosphere, then there is indeed a large carbon source. However, permafrost areas currently are mostly tundra or tundra-boreal forest biomes, which have relatively low biomass carbon stores. With warming, there would be more forest expansion into formerly permafrost areas, which may compensate for the respiration of permafrost carbon. Second, with regard to large-scale methane release from thawing permafrost, currently available science indicates that this is unlikely. First, despite the ongoing Arctic warming, there is no evidence (from precise atmospheric measurements of methane) that Arctic methane emissions are increasing. Second, an ice core study that I led a number of years ago* indicated that “old” carbon sources (carbon sources depleted in the radioactive carbon–14 isotope) did not play a large role in a rapid methane increase that was associated with a period of warming 11,600 years ago. Permafrost carbon is old and relatively low in carbon–14 content. That warming provides a partial analog to what is happening today. While we can’t with 100% certainty rule out the possibility of large methane emissions from thawing permafrost in the future, the scientific data available to date indicate that the probability of such emissions is low. Petrenko et al (2009) 14CH4 Measurements in Greenland Ice: Investigating Last Glacial Termination CH4 Sources, Science Peter Neff Assistant Research Professor, University of Minnesota: The author’s facts about methane are generally accurate, but he amps up concern about catastrophic release of methane from permafrost beyond what evidence supports. Scientists also investigate whether methane frozen at the seafloor of some continental shelves can be catastrophically be released to the atmosphere. However, existing evidence suggests that natural processes prevent catastrophe. Marine methane (gas hydrates) are heavily processed in the water column, and no contribution to the atmosphere has yet been observed. See an excellent review by Carolyn Ruppel of the US Geological Survey and John Kessler of the University of Rochester*, which was also summarized in the popular press. Ruppel and Kessler (2017) The interaction of climate change and methane hydrates, Reviews of Geophysics “The IPCC reports also don’t fully account for the albedo effect (less ice means less reflected and more absorbed sunlight, hence more warming); more cloud cover (which traps heat); or the dieback of forests and other flora (which extract carbon from the atmosphere). Each of these promises to accelerate warming” Charles Koven Staff Scientist, Lawrence Berkeley National Lab: This statement is a mixture of true and false claims. Physical feedbacks like albedo and cloud cover are most definitely included in Earth system models (ESMs) that are used to make future climate projections, so while the phrase “fully account for” isn’t well defined, the statement as written seems incorrect. As of the 5th IPCC report, biogeochemical feedbacks from permafrost were not explicitly taken into account in fully-coupled ESM simulations. However, some simulations to quantify permafrost CO2 and CH4 feedbacks had been done as of that time and reported in the assessment text, and since then these types of studies have been expanded. The central estimate of the additional contribution of warming from these permafrost feedback processes is on the order of about 20 Pg C released per degree celsius global mean temperature change—or in physical terms about 0.1 watts per meter squared per degree Celsius—which is an important contribution to warming but likely less catastrophic than presented here. However, the uncertainty on these projections does remain high and I don’t think we can completely exclude the possibility of more serious permafrost-driven feedbacks yet. Feedbacks arising from forest dieback is something that is included in some but not all ESMs used to make climate projections (i.e., those that have a “dynamic vegetation” component as opposed to a static, prescribed biogeography). Most carbon cycle models used in ESMs for climate assessments have extremely simplified treatment of forest mortality processes but, some do try to resolve this process, so while the uncertainty due to this process is extremely high and poorly captured in current ESM-based projections, it is not correct to say that it is not accounted for at all. Also, the text implies that all feedback processes are positive, destabilizing feedbacks, which isn’t the case. There are also numerous negative, stabilizing feedbacks, that exist in the planet and that are also captured to various degrees in our models of the planet. As with the positive feedbacks, the uncertainty on these is large and most likely it is poorly captured by the current generation of ESMs. Ted Letcher Research Scientist, Cold Regions Research and Engineering Lab: “More cloud cover (which traps heat)” is a gross over-simplification regarding the role of clouds as a tuning knob for Earth’s climate. While it is true that clouds can act as a blanket and trap more heat, they also serve to reflect sunlight (see the prior sentence regarding the albedo effect). Which cloud effect ultimately wins out has to do with the optical thickness of the cloud (how reflective it is) and (as a rough approximation), the cloud height. As a quick rule: Higher clouds will act better as a blanket since they are both colder (and therefore radiate less energy to space) and typically optically thin. Conversely, lower clouds act more as a reflector since they are warmer and optically thick. The IPCC report does generally show a net positive cloud feedback, indicating global cloud feedbacks will lead to additional warming, but cloud feedbacks are extremely complicated and highly uncertain. Alexis Berg Research Associate, Harvard University: I am not sure what the author means here. The climate models whose projections the IPCC reports are based on definitely account for the changes in albedo from reduced sea-ice and snow cover as the world warms (although not necessarily changes in glaciers and ice caps extents—e.g. Greenland—which is maybe what the author means here), as well as the effect of changes in clouds (actually, the largest source of uncertainty in climate models projections); most models also now account for changes in vegetation and include an interactive carbon cycle (for instance, how a reduction in forest diminishes the land carbon sink). 4. Climate change in Earth’s past can be used to understand the workings of the climate system and refine our expectations for the long-term impacts of modern warming. “In fact, all but the one [extinction event] that killed the dinosaurs were caused by climate change produced by greenhouse gas. The most notorious was 252 million years ago; it began when carbon warmed the planet by five degrees, accelerated when that warming triggered the release of methane in the Arctic, and ended with 97 percent of all life on Earth dead.” David Archer Professor, University of Chicago: Other agents of destruction have been invoked for the end Permian extinction, involving toxic fluorine fumes from volcanic emissions or sulfides from the deep sea. Lee Kump Professor, PennState University: Climate change accompanies all of the mass extinctions, although severe warming isn’t necessarily always to blame. For example, the extinction at the end of the Ordovician occurred during a brief, enigmatic glaciation. The “notorious” extinction 242 million years ago, at the end of the Permian, clearly (based on oxygen isotope proxy data) was accompanied by significant global warming likely triggered by the eruption of the “Siberian Traps” volcanoes, with concomitant buildup of carbon dioxide. Whether methane was released remains speculative, although not unlikely. The species extinction percentage in the ocean could have approached 97%, the proportion was likely lower on land. “the geological record shows that temperature can shift as much as ten degrees or more in a single decade” Alexis Berg Research Associate, Harvard University: I am not sure, again, what the author is referring to here. Ice cores have shown that Greenland temperatures can swing by as much as 10 °C during glacial-interglacial transition*, yes, but we are not talking about global mean temperature here, more about swift reorganization of atmospheric circulation in interglacial glacial transitions that leads to strong regional change in the Arctic. I am unaware of studies showing past global-scale warming of 10 °C in a decade. Note, however, that even global warming of a few degrees C in a century or two would be extremely fast, by geological standards. “The last time the planet was even four degrees warmer, Peter Brannen points out in The Ends of the World, his new history of the planet’s major extinction events, the oceans were hundreds of feet higher.” Alexis Berg Research Associate, Harvard University: I don’t know what time period the author is referring to here, but closer to us, during the last interglacial (roughly 120,000 years ago), Earth was ~2 °C warmer than temperatures in the 19th century, and sea levels were about 5-6 meters higher. This suggests that even “good-case, 2 °C” long-term warming in our future could also raise oceans by that much eventually, even if the pace of that rise (and thus the amount of rise by 2100) is uncertain. “Things almost certainly won’t get that hot this century, though models of unabated emissions do bring us that far eventually.” Alexis Berg Research Associate, Harvard University: This brings up an important point: while historically, IPCC-type projections stop in 2100 by convention, warming does not stop then, in particular for very high (perhaps implausibly high) greenhouse gas emission scenarios: warming goes on in the following centuries, up to ten of degrees in the worst case. Source: IPCC Note that the larger the warming, the larger the uncertainties between climate models (the shading). 5. Warming and drought will negatively impact agriculture—varying with the crop and the region. “The end of food” Richard Betts Professor, Met Office Hadley Centre & University of Exeter: This is hyperbole.Yes there are threats to crop production and other aspects of food security, but the scientific analyses do not suggest an actual “end of food”—it is more a case of regional winners and losers. Not all current food-producing regions are projected to lose their productivity. A redistribution of production would still still be a major issue that society will need to deal with, and may well require growing crops in new places, but this is not the same as suggesting that food supplies will completely come to an end. “the basic rule for staple cereal crops grown at optimal temperature is that for every degree of warming, yields decline by 10 percent. Some estimates run as high as 15 or even 17 percent. Which means that if the planet is five degrees warmer at the end of the century, we may have as many as 50 percent more people to feed and 50 percent less grain to give them.” David Battisti Professor of Atmospheric Sciences, University of Washington: These numbers stem from the results of controlled field sites (in, for example, the Philippines, India and Mexico) and refer to the impact of local temperature changes on yield, all else being equal. (Also, note that the major grain producing regions are in the midlatitudes, where the projected temperature increases are substantially greater than the projected global average temperature increase.) The projected changes in precipitation are sufficiently uncertain that it is not possible to quantitatively account for the impact of their changes, although the IPCC 2013 WG1 Report concludes: “In many mid-latitude and subtropical dry regions, mean precipitation will likely decrease, while in many mid-latitude wet regions, mean precipitation will likely increase under the RCP8.5 scenario.” (In IPCC lingo, “likely” is greater than 2/3 chance.) Finally, there is also a fertilization effect associated with increasing CO2, although studies have shown that the deleterious impact of increasing temperature far outweigh the impact of increased CO2. Alexis Berg Research Associate, Harvard University: Well, for one thing, if food supplies decrease by 50%, one could argue that it is unlikely population would increase by 50% in the meantime… More to the point, the back-of-the-envelope calculation from the author, here, implies that all crops are grown at optimal temperature, which they are not. Exact, global impacts of global warming on agriculture are difficult to quantify. One must also account for the effect of increased atmospheric CO2 on plant photosynthesis, as well as precipitation changes, which are uncertain in particular over land in the Tropics. Adaptation and management could also influence changes a lot. Generally, the estimate has been that warming would be neutral for mid-and high latitudes, up to a point, while being detrimental to agriculture in low latitudes. But again, global, quantitative impacts are uncertain, especially for large warming. I haven’t seen studies suggesting a global decrease by 50%. “as the pathbreaking work by Rosamond Naylor and David Battisti has shown, the tropics are already too hot to efficiently grow grain, and those places where grain is produced today are already at optimal growing temperature — which means even a small warming will push them down the slope of declining productivity.” David Battisti Professor of Atmospheric Sciences, University of Washington: This statement is mostly accurate. To be more precise, it would read “Temperature in the tropics is already greater than the optimal temperature for growing the major crops (rice, wheat, maize). Most of the major grain-producing regions of the world are in the midlatitudes (e.g. the US, Europe, Ukraine, China), where today growing season temperatures are nearly optimal. Hence, warming due to increased CO2 will indeed decrease the yield of these crops in these high-producing regions.” “with some of the world’s most arable land turning quickly to desert” Alexis Berg Research Associate, Harvard University: What regions? Is this a statement about the present, or the future? If about the present, I am unaware of major arable land regions currently facing desertification. Current drought trends—whether droughts, on the global scale, are increasing in extent and/or severity—and their future under global warming, is still somewhat uncertain and a topic of ongoing research. “Precipitation is notoriously hard to model, yet predictions for later this century are basically unanimous: unprecedented droughts nearly everywhere food is today produced. By 2080, without dramatic reductions in emissions, southern Europe will be in permanent extreme drought, much worse than the American dust bowl ever was. The same will be true in Iraq and Syria and much of the rest of the Middle East; some of the most densely populated parts of Australia, Africa, and South America; and the breadbasket regions of China.” David Battisti Professor of Atmospheric Sciences, University of Washington: In general, there is large uncertainty in how precipitation will change due to increased greenhouse gases, including the Sahel in Africa, Australia, and many of important grain producing regions of the world (e.g., the US, Ukraine, China). Under high emission scenarios, models consistently project annual averaged drying in a few places by the end of the Century: e.g. southern Europe, northern Africa, and southern Africa. The IPCC 2013 WG1 Report concludes: “In many mid-latitude and subtropical dry regions, mean precipitation will likely decrease, while in many mid-latitude wet regions, mean precipitation will likely increase under the RCP8.5 scenario.” (In IPCC lingo, “likely” is greater than 2/3 chance.) Alexis Berg Research Associate, Harvard University: This is not true for precipitation. See the right panel on the plot below: What the author is probably referring to is drought projections not based on precipitation alone, but rainfall+temperature, as shown for instance by the Palmer Drought Index. However, there is a debate as to how best to interpret such projections in terms, for instance, of impacts on vegetation (and crop yields) or water resources*. So I would argue things are more uncertain than the authors implies here. Milly and Dunne (2016) Potential evapotranspiration and continental drying, Nature Climate Change Daniel Swain Climate Scientist, University of California, Los Angeles: I agree with Alexis Berg’s comment above. Projections regarding widespread occurrence of historically unprecedented drought are in most cases the product of very strong warming that overwhelms any changes (positive or negative) in precipitation in terms of net moisture. Obviously, temperature-driven droughts will still have large and adverse consequences for agriculture in many regions—so the broader point made here regarding large risks to food production is reasonable. “None of these places, which today supply much of the world’s food, will be reliable sources of any.” David Battisti Professor of Atmospheric Sciences, University of Washington: Even with no change in the natural variability in growing season temperature, increasing summer averaged temperature will likely lead to increased volatility in grain production in the midlatitudes because of the nonlinear relationship between temperature and yield. See section 7.4 of the IPCC 2013 WG2 Report for a recent summary. Africa and “Iraq, Syria and much of the Middle East” are not on the list of the world’s major grain producer regions. “In the sugarcane region of El Salvador, as much as one-fifth of the population has chronic kidney disease, including over a quarter of the men, the presumed result of dehydration from working the fields they were able to comfortably harvest as recently as two decades ago.” Victor Venema Scientist, University of Bonn, Germany: If this author already writes “presumed result”, I would love to see a reference to the scientific literature. It would be quite surprising if the 1-1.5 °C warming we have seen up now makes such a differences. Source: Berkeley Earth 6. Air quality can be affected by both emissions of pollutants and by weather patterns that contribute to urban smog, for example. Climate change can also affect disease transmission by altering the conditions required by vectors. “The warmer the planet gets, the more ozone forms, and by mid-century, Americans will likely suffer a 70 percent increase in unhealthy ozone smog, the National Center for Atmospheric Research has projected.” David Archer Professor, University of Chicago: Note that ozone concentrations are also determined by emissions of NOx and hydrocarbons, which can be controlled. “[Carbon dioxide] just crossed 400 parts per million, and high-end estimates extrapolating from current trends suggest it will hit 1,000 ppm by 2100. At that concentration, compared to the air we breathe now, human cognitive ability declines by 21 percent.” Alexis Berg Research Associate, Harvard University: There is, indeed, some research showing impairments in cognitive function test scores in people exposed to CO2 concentrations in the 950-1,000 ppm range, and even significantly worse performance when CO2 gets to 1,500 and 2,500 ppm. But note that concentrations greater than ~1,000 ppm are, already today, often found in poorly ventilated rooms and buildings. At even higher concentrations, documented metabolic and health effects start to appear—in fact, the safe limit for permanent, long-term exposure to higher concentration of CO2 does not appear to be well known. It seems like NASA and the Navy set that limit around 5,000 ppm for their crews in submarines and spacecrafts. Allen et al (2016) Associations of Cognitive Function Scores with Carbon Dioxide, Ventilation, and Volatile Organic Compound Exposures in Office Workers: A Controlled Exposure Study of Green and Conventional Office Environments, Environmental Health Perspectives “That is especially bad because the Amazon alone provides 20 percent of our oxygen.” Alexis Berg Research Associate, Harvard University: This sentence somehow implies that deforesting the Amazon would reduce atmospheric oxygen by 20%. This is not true. To quote Wally Broecker, who is cited later in the article: “Simply put, our atmosphere is endowed with such an enormous reserve of this gas that even if we were to burn all our fossil fuel reserves, all our trees, and all the organic matter stored in soils, we would use up only a few percent of the available O2. No matter how foolishly we treat our environmental heritage, we simply don’t have the capacity to put more than a small dent in our O2 supply. Furthermore, the Earth’s forests do not play a dominant role in maintaining O2 reserves, because they consume just as much of this gas as they produce. In the tropics, ants, termites, bacteria, and fungi eat nearly the entire photosynthetic O2 product. Only a tiny fraction of the organic matter they produce accumulates in swamps and soils or is carried down the rivers for burial on the sea floor.”“The Arctic also stores terrifying bugs from more recent times. In Alaska, already, researchers have discovered remnants of the 1918 flu that infected as many as 500 million and killed as many as 100 million” Kristie Ebi Professor, University of Washington: A series of cholera pandemics and 1918 Spanish influenza were global pandemics causing high mortality long before anthropogenic climate change began influencing the geographic range of climate-sensitive health outcomes. The World HealthOrganization andnational health systems are preparing for changes in the intensity of transmission, geographic range, and seasonality of climate-sensitive infectious diseases. Certainly much more needs to be done, but thearticle implies national andInternational public health organizations and institutions will not take action when diseases emerge or re-emerge. This is not consistent with the responses to Ebola, Zika, and other recent events. ” You don’t worry much about dengue or malaria if you are living in Maine or France. But as the tropics creep northward and mosquitoes migrate with them, you will.” Kristie Ebi Professor, University of Washington: The statement about the malaria incidence of malaria doesn’t mention the significant decline in the number of cases over the past several decades based onconcerted publichealth efforts. Continuing and scaling up those programs would protect future populations from any changes in disease incidence associated with climate change. “As it happens, Zika may also be a good model of the second worrying effect — disease mutation. One reason you hadn’t heard about Zika until recently is that it had been trapped in Uganda; another is that it did not, until recently, appear to cause birth defects.” Kristie Ebi Professor, University of Washington: It would be helpful to know the source of the statements about Zika. Zika was first recognized in Uganda, but has not been trapped there. Zika has been moving around the world for the past few years, presumably associated with trade and travel. With limited surveillance of Zika and with limited numbers of cases, it isn’tpossible to say whether the disease caused birth defects beforethe large outbreak lastyear; research isunderway to determine that. 7. The ocean are affected not just by rising temperatures, but by changes in chemistry caused by higher concentration of carbon dioxide in the atmosphere. “That isn’t all that ocean acidification can do. Carbon absorption can initiate a feedback loop in which underoxygenated waters breed different kinds of microbes that turn the water still more “anoxic,” first in deep ocean “dead zones,” then gradually up toward the surface[…]This process, in which dead zones grow like cancers, choking off marine life and wiping out fisheries, is already quite advanced in parts of the Gulf of Mexico and just off Namibia, where hydrogen sulfide is bubbling out of the sea along a thousand-mile stretch of land known as the ‘Skeleton Coast.’” Lee Kump Professor, PennState University: Ocean acidification per se doesn’t enhance anoxia: anoxia (loss of oxygen) results from warming (warm water holds less dissolved gas like oxygen), which would be the consequence of atmospheric CO2 buildup, as might more sluggish ocean mixing. It also is enhanced by increased nutrient delivery to the ocean from more rain and river flow on land under the warmer climate. More nutrients mean more algae growth in the uppermost ocean, more decaying organic matter below the surface, and thus less oxygen. Low oxygen zones would spread as the ocean became warmer and river flow increased as the event progressed. When oxygen is exhausted, bacteria do “breathe” other oxygen-containing compounds including sulfate and respire hydrogen sulfide. The coast of Namibia does experience these extreme conditions episodically, but such conditions are unlikely to spread globally until centuries to millennia of warming and eutrophication have occurred. Hydrogen sulfide likely contributed to the mass extinction, but the warming itself as well as other volcanic emanations like chlorine, fluorine, and sulfur dioxide were equally if not more important drivers of the extinction. The recovery from the extinction did take millions of years. “they do know that in acid waters, oysters and mussels will struggle to grow their shells, and that when the pH of human blood drops as much as the oceans’ pH has over the past generation, it induces seizures, comas, and sudden death.” David Archer Professor, University of Chicago: Human blood chemistry is regulated in a way the sea water is not, so this statement is only marginally relevant. UPDATE (15 July 2017): Here is the list of statements that have been modified from the original version of the New York Magazine article: – added: “To read an annotated version of this article, complete with interviews with scientists and links to further reading, click here.” – modified: “there are alarming stories every day, like last month’s satellite data showing the globe warming, since 1998, more than twice as fast as scientists had thought.” now reads: “there are alarming stories in the news every day, like those, last month, that seemed to suggest satellite data showed the globe warming since 1998 more than twice as fast as scientists had thought (in fact, the underlying story was considerably less alarming than the headlines).” – modified: “the geological record shows that temperature can shift as much as ten degrees or more in a single decade.” now reads: “the history of the planet shows that temperature can shift as much as five degrees Celsius within thirteen years.” – added:“This article has been updated to provide context for the recent news reports about revisions to a satellite data set, to more accurately reflect the rate of warming during the Paleocene–Eocene Thermal Maximum […]”

https://science.feedback.org/review/breitbart-article-falsely-claims-measured-global-warming-fabricated-james-delingpole/

-1.8

Breitbart, by James Delingpole, on 2017-07-09.

"‘Nearly All’ Recent Global Warming Is Fabricated, Study Finds"

This Breitbart article by James Delingpole claims that the observed warming of Earth’s surface temperatures is largely a fabrication by scientists who have altered the measurements. The source for this claim is a document written by three individuals who have no track record of publishing scientific research on the topic, and have not submitted their work to peer-reviewed scientific journals, but simply uploaded a pdf on a wordpress blog. Scientists who reviewed the article found that its claims are false and misleading. Data are indeed adjusted to accurately account for things like changes in the instruments used to make measurements or the relocation of weather stations. However, the impact of these adjustments on the global temperature record is actually small, and the warming trend of the last century would appear to be larger without the adjustments, in contradiction with the claims in the Breitbart article.See all the scientists’ annotations in contextGUEST COMMENTS: Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: In general, their argument about removing cyclical behavior comes from comparing old 1980s NASA GISTemp records to those of today. What they don’t tell you is that the 1980 record in question (in addition to being graphed on a different baseline than all the other series) only comes from around 500 land stations almost entirely in the Northern Hemisphere and does not include any ocean data at all. There is a well known warm period in the mid-to-high latitude land areas of the Northern Hemisphere in the 1930s and 1940s, but it does not really show up much in the oceans and not at all in the S Hemisphere. As scientists have collected more historical temperature records from around the world in the past 35 years, we have created more complete records that show less warmth in that period simply because they cover more of the planet. See the NASA website for a good discussion of this. Ultimately all of these comparisons to past records are a bit of a distraction. We have all the raw temperature records today, and we can compare them to the adjusted data to see what, exactly, adjustments do to the temperature record. It turns out that adjustments actually result in less warming over the past century, not more. If we scientists were “cooking the books”, then we are doing so in the wrong direction.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Peter Thorne Professor, Maynooth University: Firstly, as far as I can tell the report [the article is based on] is not published in the peer reviewed literature, yet that is the strong implication given. Then the central money figure is grossly misleading. It takes the difference between consecutive versions of the NOAA NCEI product and purports that these differences are the adjustments being applied to the raw data. I think the only phrase one could, with any validity, use here is “not even wrong”. Both the series have been adjusted, and to pretend otherwise is either showing willful ignorance or duplicity. Taking the difference solely shows the change in adjustments applied and not the total adjustments as is being implied. Indeed, the total common adjustments being applied to both versions of the NOAA NCEI product dwarf those being shown. And the biggest adjustment of all—and only one that really matters—is that applied to account for the move from bucket measurements to engine room intakes over the oceans in the (pre-)WW2 period. This adjustment serves to greatly reduce (not increase) the centennial scale surface temperature trend. Source: IPCC AR5 Fig 2.16 (The blue line—”ICOADS”—is the uncorrected data.) Finally, the finding of unequivocal warming does not rest solely upon surface temperature records. Rather it relies upon a broad suite of indicators (see e.g. FAQ2.1 of IPCC AR5) that all point unambiguously to the conclusion that Earth is running a fever. These findings and the recent surge in temperatures are corroborated by a broad range of other non-physical indicators (phenology, etc.) and also by a suite of modern reanalysis products. For so many analyses to be wrong is all but impossible. If the authors are correct they must explain away all these very many corroborating lines of evidence put together by a diverse range of groups using a huge range of measurements and analysis techniques. They can’t, and they won’t, instead preferring to cast doubt on small details, and making misleading assertions, all the while fervently hoping that their audience misses the big picture, to sow doubt and confusion. Jennifer Francis Senior Scientist, Woods Hole Research Center: The authors of this article and of the study it references clearly have a very limited understanding of the painstaking methods used to ensure that surface temperature records are based on correct and unbiased measurements. Temperature databases from major scientific groups world-wide agree with each other, and also with measurements from independent sources, such as satellites. Shaun Lovejoy Professor, McGill University: The article is mostly misleading because it gives evidence (a graph) that does not support the interpretation that is in given in the text. A reader would have to be somewhat knowledgeable about global warming to realize that the interpretation is unjustified. Peter Neff Assistant Research Professor, University of Minnesota: In a cursory attempt at both reporting and climate science, the author glibly highlights a document heavy on accusation and light on reasoned engagement with fact. Implying nefarious motives behind temperature measurement bias correction without providing readers any indication of why this is necessary is misleading and a dereliction of the author’s journalistic responsibility. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from the article; comments and replies are from the reviewers. 1. Adjustments for known issues are necessary in any dataset, but the adjustments made to surface temperature data have not inflated the long-term warming trend. “‘Nearly All’ Recent Global Warming Is Fabricated, Study Finds” Victor Venema Scientist, University of Bonn, Germany: The entire study could not have been more wrong in three clear ways. 1. The adjustments are scientifically important, but rather modest for the global mean temperature. 2. The adjustments make the estimated warming smaller, not larger. Below are, for example, the raw and adjusted warming signals of the NASA GISS dataset. The how and why is discussed in this post. 3. Also without any thermometer it would be clear that the Earth is warming. Just look at sea ice, sea level rise, melting glaciers, later river freezing, earlier ice breakup, earlier spring and animal migration, movement of animals, plants, insects and ecosystems towards to poles and up mountains, etc. “the adjusted data” Peter Neff Assistant Research Professor, University of Minnesota: It is surprising that, despite adjusted data being the crux of the arguments made here and in the study referred to, the author never explains why one may need to adjust measurements made on the ground or by satellites. There has been significant media coverage recently of some of the adjustments relating to temperature measurements made by satellites. Simply from a practical standpoint, it is beneficial to consider what is involved in sustaining the orbit of a satellite. Once put into orbit, a satellite will slowly “decay” away from its intended orbit as it is pulled nearer to Earth by gravity and other effects. Unless it has its own propulsion to correct for this, it will eventually be pulled out of orbit. This decay affects the exact time of day during which the satellite repeats measurements over one location. For example, from 1995 to 2005, the time of day that a NOAA satellite (NOAA-14) passed over the equator changed by more than 6 hours. The temperature in Quito at 12pm local time versus 6pm local time is quite different, so the satellite measurement must be corrected for this and other effects. More details from this excellent article by Zeke Hausfather. “alarmist organizations like NASA, NOAA, and the UK Met Office differs so markedly from the original raw data that it cannot be trusted.” Peter Neff Assistant Research Professor, University of Minnesota: These are some of the most respected, independent and transparent institutions collecting and ensuring free and open access to climate data of the highest quality. If it were not for these agencies, our ability to evaluate global temperature trends at all would be in the stone age. It might be more useful to thank these international agencies for providing data with which the author makes their arguments. Victor Venema Scientist, University of Bonn, Germany: The differences between the raw and the adjusted data are small for the global mean temperature. The warming estimated from adjusted data is smaller than it would have been without taking changes in the way observations were made into account. “This chart gives you a good idea of the direction of the adjustments.” Peter Thorne Professor, Maynooth University: The chart provides solely a view as to the changes in applied adjustments between consecutive versions of one product. It does not reflect the totality of the adjustments being applied. Showing total adjustments would highlight that these deltas were dwarfed by the existing adjustments applied to the 2008 version. Specifically, the very large spurious warming resulting from biases in the raw marine data record over the late 1930s / early 1940s. The net effect of adjustments in all datasets is to reduce the centennial timescale warming in all the surface temperature products. Victor Venema Scientist, University of Bonn, Germany: This chart does not show the adjustments. It shows an unsourced graph with the difference between two datasets. This is also due to increases in the amount of data used and thus also increases in coverage. In as far as the reason are adjustments, a likely reason would be the adjustments of the sea surface temperature that make global warming smaller. Older bucket measurements are cooler than modern buoy measurements because the water cools by evaporation between taking the bucket out of the water and reading the thermometer. In the past these adjustments were thought to be larger than modern estimates. So the “scandal” here would be that scientists were conservative in their early estimate of global warming. “The blue bars show where the raw temperature data has been adjusted downwards to make it cooler; the red bars show where the raw temperature data has been adjusted upwards to make it warmer.” Peter Thorne Professor, Maynooth University: It does no such thing as both the series are adjusted. Hence it is impossible from the graph as constructed to make such an inference. To do so would require taking the adjusted data away from the raw data which is not what is being done here. Jennifer Francis Senior Scientist, Woods Hole Research Center: Adjustments are made for good reasons. One of the most common ones is to account for a station located in a growing city, where the urban heat island effect would add spurious warming. In most cases the adjustments reduce, not increase, the warming in the record. “Note how most of the downward adjustments take place in the early twentieth century and most of the upward take place in the late twentieth century.” Shaun Lovejoy Professor, McGill University: Even if all the adjustments were unjustified (as the Breitbart piece implies), they would only change the magnitude of the overall warming by about 0.1 °C; from about 1 °C to about 0.9 °C. This graph is nearly irrelevant to the question of anthropogenic warming! It could also be mentioned that the 20th Century reanalysis* which uses NO temperature data from any stations found almost an identical warming (to within 0.1 °C) as 5 other series based on station data. The information in the Breitbart graph is irrelevant to the issue of anthropogenic warming; it is at most a footnote. Compo et al (2013) Independent confirmation of global land warming without the use of station temperatures, Geophysical Research Letters Lovejoy (2017) How accurately do we know the temperature of the surface of the earth?, Climate Dynamics “Each dataset pushed down the 1940s warming” Victor Venema Scientist, University of Bonn, Germany: The second world war increased the percentage of American navy vessels, which make engine intake measurements, and decreased the percentage of merchant ships, which make bucket measurements. Source: UK MetOffice Engine intake observations are typically warmer than bucket measurements because the water cools due to evaporation before the thermometer is read. That produces a spurious warm peak in the raw data. “cyclical temperature patterns” Victor Venema Scientist, University of Bonn, Germany: The report wants to see the summer heat waves of the Dust Bowl in America in the 1930s in the global average annual mean temperature. The figurebelow shows the summer temperature difference between the Dust Bowl year 1936 and now. The affected area, which was warmer in 1936 than now (blue), is about 2% of the Earth’s surface. 2. The document the Breitbart article relies on has not been peer-reviewed by scientists who work in this field. “The peer-reviewed study by two scientists and a veteran statistician looked at the global average temperature datasets[…]” Peter Thorne Professor, Maynooth University: As far as I can tell the linked report is not accepted for any journal and thus peer-reviewed is willfully misleading at best. Ted Letcher Research Scientist, Cold Regions Research and Engineering Lab: In addition to not being peer reviewed, the study also doesn’t appear to cite ANY peer-reviewed literature to support its conclusions, nor does the report provide any additional references. Furthermore, the report appears to have a clear dismissive tone towards peer-reviewed research and uses dubious language such as “Climate Alarmist”, further straining the credibility of the report this article is based solely on. Jennifer Francis Senior Scientist, Woods Hole Research Center: If this author knew anything about the process of scientific research and publication, he would realize just how ridiculous this statement is. Note that the study reported in this article has not been published in any reputable peer-reviewed journal, undoubtedly because it would never pass muster. 3.The Breitbart article claims that we cannot say whether the Earth has warmed, but many lines of evidence independent from temperature measurements also confirm the warming trend. “used by climate alarmists to argue that recent years have been “the hottest evah” and that the warming of the last 120 years has been dramatic and unprecedented.” Peter Thorne Professor, Maynooth University: The IPCC AR5 concluded that warming was unequivocal. This finding rested upon a wealth of evidence and not solely upon surface records. However, each decade for the past three decades has been warmer than all preceding decades in the instrumental record by a greater extent than quantified uncertainties. This finding applies using older or newer versions of the datasets. “Nearly all of the warming they are now showing are in the adjustments.” Victor Venema Scientist, University of Bonn, Germany: That amounts to the claim that the Earth is not really warming. Even without looking at any thermometer data, even if we would not have invented the thermometer we would know it is warming: Glaciers are melting, from the tropical Kilimanjaro glaciers, to the ones in the Alps and Greenland. Arctic sea ice is shrinking. The growing season in the mid-latitudes has become weeks longer. Trees bud and blossom earlier. Wine grapes can be harvested earlier. Animals migrate earlier. The habitat of plants, animals and insects is shifting poleward and up the mountains. Lakes and rivers freeze later and break up the ice earlier. The oceans are rising.

https://science.feedback.org/review/earth-is-not-at-risk-of-becoming-a-hothouse-like-venus-as-stephen-hawking-claimed-bbc/

Incorrect

BBC, Stephen Hawking, 2017-07-02

Trump's action could push the Earth over the brink, to become like Venus, with a temperature of two hundred and fifty degrees, and raining sulphuric acid.

Incorrect: It is not possible for Earth’s climate to become as extreme as Venus’ climate in the foreseeable future. And even extreme global warming would not be linked to sulfuric acid precipitation, which occurs on Venus because of volcanic emissions of sulfur gas.

While feedbacks (like the release of greenhouse gas from thawing permafrost) can amplify climate change, the effect has limits. In its current state, Earth is not at risk of “runaway warming” that reaches the extreme temperatures of Venus.

We are close to the tipping point where global warming becomes irreversible. Trump's action could push the Earth over the brink, to become like Venus, with a temperature of two hundred and fifty degrees, and raining sulphuric acid.

Andrew Dessler Professor, Texas A&M University: This is definitely hyperbole. What’s correct in it is that Venus has a massive atmospheric greenhouse effect, resulting in a surface temperature of 450 °C or 850 °F (compared to Earth’s of 14 °C or 58 °F). And basic physics tells us that, as we add greenhouse gases, we increase the strength of our own greenhouse effect. That said, we are far, far, far away from either becoming Venus or the amount of warming suggested by Hawking. Best guess warming of the 21st century is a few degrees C. Make no mistake, this could be terrible for humans and ecosystems, but it’s a lot less than suggested above. And while I don’t think the planet is near a “tipping point,” I do think that climate change is already irreversible because of the long lifetime of CO2 in the atmosphere (centuries to millennia) and the large heat capacity of the oceans. It will take 10,000s of years after CO2 emissions cease for the climate to cool back down to pre-industrial levels (unless we geoengineer). That means that the decisions we make on emissions over the next few decades will determine the climate for the next many thousands of years. To me, this is one of the most troubling parts of the climate change problem. Finally, where does “raining sulphuric acid come from”? That makes no sense—why does a warming climate lead to more sulfur in the atmosphere? That seems completely unsupportable. Christopher Colose Research Scientist, SciSpace LLC, NASA Goddard Institute for Space Studies: As brilliant as Stephen Hawking is, fortunately for life on Earth, this comment is not correct. Venus is actually much hotter than 250 degrees (on any conventional temperature scale), but the pathway it took to being a hot, dead world and a completely failed biosphere is virtually impossible to achieve on modern Earth. The key to achieving a runaway greenhouse on Earth is for our planet to absorb more energy from the Sun than it can actually lose to space at longer wavelengths. There are a few limits to the rate at which bodies can lose energy. One simple limit that applies for a bare rock in space is the Stefan-Boltzmann law, which caps the emitted energy at a constant multiplied by the fourth power of the object’s temperature. In this case, the temperature of the rock will simply be whatever is required for it to emit infrared energy as the same rate at which it gets from the Sun. However, another limit arises in a very moist atmosphere due to the infrared absorption features of water. On modern Earth, adding CO2 to the atmosphere means you decrease the emission to space, but the eventual warming of the planet will increase the emission to space. The net result is that the emission to space is essentially unchanged as a consequence of a break-even “tug of war” between CO2 absorption and temperature. In a very hot, steam atmosphere, however, the emission to space could become decoupled from the surface temperature entirely, and the planet would keep getting hotter if it absorbed more energy than it could shed off. Eventually, at the critical point of water (~705 °F) there is no density discontinuity between the liquid and vapor phases, the ocean surface loses its distinct character, and the ocean is the atmosphere. Earth’s fully vaporized oceans would give a surface pressure of about 270 modern atmospheres. Liquid water is not stable at the surface of Venus today, which is over 850 °F. An ancient vaporized ocean on Venus (for which there is some isotopic evidence for) would eventually be lost to space by the breakup of high altitude water by intense wavelengths of sunlight; this sustained water loss does not occur on Earth due to very cold temperatures in the upper troposphere, which keeps most of the vapor near the surface. In fact, the modern state of Venus (a hot planet with about 90 Earth atmospheres of CO2) can be described as a “post-runaway phase” arising because Venus lost nearly all of its water. On Earth, most of the oxidized carbon is in carbonate rocks, which form in the presence of surface liquid water. Indeed, this is the long term sink of carbon in Earth’s atmosphere, and the eventual (hundreds of thousands of years from now) removal mechanism for the excess anthropogenic CO2. However, these carbonates cannot be deposited on Venus. Instead, with no carbon sink,Venus contains a comparable amount of carbon as Earth does, except it is in the atmosphere rather than locked up in carbonate rocks. Luckily, Earth does not absorb enough Sunlight for this runaway scenario to be a credible threat. Adding CO2 to the atmosphere would never bring Earth near the critical point of water or lock Earth into a state where it can’t lose enough energy to cool off. It is theoretically possible, however, to make modern Earth hot enough such that the upper atmosphere becomes quite wet and conducive to substantial water loss to space. Such a large atmospheric warming also elevates the tropopause height well into the modern stratosphere, and large ozone concentrations could not occur in the presence of tropospheric water vapor content, so the UV protective ozone layer would be engulfed. In this scenario, huge amounts of water could still be irreversibly lost to space without a complete vaporization of the ocean. Such a scenario would still be unlikely to occur, however, even if humans burned all of the fossil fuel reserves, and would require many tens of degrees of additional warming. A somewhat more credible concern that could occur at CO2 concentrations of ~2,000 ppm (a few doublings relative to today) is opening up regions of the globe where humans can’t lose body heat efficiently[1]. Hyperthermia would be induced within hours in significant fractions of the planet for global temperature rises of 15-20 °F or so. This is still a bit outside the bounds of what we expect to occur this century. Hawking is correct that unabated fossil fuel emissions will continue to warm the planet. A smooth warming trend is still a major problem for social infrastructure, however, even if there were no major tipping points. While there may be irreversible events in subcomponents of the climate system, such as melting of the Greenland ice sheet, or die-off of the Amazon, there is no magic threshold at which warming goes from benign to irreversibly terrible. Therefore, we should still focus on limiting the magnitude of future warming, despite the fact that Earth will not become Venus. [1] Sherwood and Huber (2010) An adaptability limit to climate change due to heat stress, PNAS Alexis Tantet Postdoctoral researcher, Hamburg University, Meteorologisches Institut: According to the Fifth Assessment Report of the IPCC (Chap. 12)[1], it is likely that global mean temperature will rise by 0.3 to 1.7 degrees C by the end of the 21st century compared to the end of the 20th century for the lowest scenario of greenhouse gas emissions, or 2.6 to 4.8 degrees C for the highest emissions scenario. The magnitude of this increase is largely dependent on our ability to curb greenhouse gases emissions. As one of the major contributors to greenhouse gases emissions, the role of the USA in determining which scenario will be followed cannot be undermined. There is on the other hand low confidence and little consensus on the likelihood that the climate system will face abrupt and irreversible changes over the 21st century[1] and there is absolutely no evidence that the climate of the Earth could become like that of Venus. While present day concentrations of greenhouse gases exceed the range of concentrations recorded in the past 800,000 years, global mean surface temperatures were about 1.9 to 3.6 degrees C higher than for pre-industrial climate during the mid-Pliocene (about three million years ago), and one has to go as far as the Early Eocene (about 50 million years ago) to find temperatures higher by 9 to 14 degrees C (see IPCC Chap. 5). [1] IPCC (2013) Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change Ken Caldeira Senior Scientist, Carnegie Institution for Science: The Earth is not at risk of becoming like Venus. We have done climate model simulations in which all available fossil fuels were burned and the resulting CO2 released into the atmosphere. The planet warmed up about 10 °C in these simulations. This was enough to melt all of the ice sheets and produce 60 meters of sea-level rise, but in no such simulation does the Earth become anything like Venus. Winkelmann et al (2015) Combustion of available fossil fuel resources sufficient to eliminate the Antarctic Ice Sheet, Science

https://science.feedback.org/review/the-atlantic-accurately-reports-study-economic-impacts-continued-climate-change-us-robinson-meyer/

1.3

The Atlantic, by Robinson Meyer, on 2017-06-29.

"The American South Will Bear the Worst of Climate Change’s Costs"

This story in The Atlantic by Robinson Meyer describes a new study on the distribution of economic impacts that result from continued climate change in the United States. The study finds that the impacts would not be uniform throughout the country, but would reduce GDP to a greater degree in southern states, for example, while the northernmost states could experience net economic benefits from warmer temperatures. Scientists who reviewed the article indicate that it accurately summarizes the study, although the topic of climate impacts is broad and complex, and can inevitably benefit from additional context.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field. Kenneth Gillingham Associate Professor, Yale University: The article is well written, engaging, and correctly described the findings of the Science article. It could have been more introspective about what the results of the Science article actually mean. (E.g. do the results still hold if the geographic distribution of population and economic activity changes in response to climate from 2012 levels? Are the differences between the south and north robust to a broader range of uncertainty than the limited uncertainty examined in the Science article?) Frances Moore Assistant Professor, University of California Davis: The article accurately describes the findings of the paper it is discussing, which is an important scientific contribution. It points out the key conclusions and contributions correctly. Gary Yohe Professor of Economics and Environmental Studies, Wesleyan University: The study makes an enormous contribution by updating aggregate economic reaction functions (sectoral and locational) across a large portion of the economy calibrated in currency and percentage changes in income for the end of the century) that will inform integrated assessment modeling efforts and estimates of the social cost of carbon for the United States. Even though it is not completely comprehensive (so the estimates and ranges continue to be lower bounds of actual totals), the estimates are higher than earlier numbers and ranges because the analysis covers more ground very carefully and digs down to county level climate risks. Spatial variability makes the aggregates less subject to the downward push of aggregating over wider areas (i.e., highs and lows do not cancel as much). Estimates of the social cost of carbon for the US should now be higher than before (they have persistently been orders of magnitude smaller than the world before now—a fact that led the EPA and the Supreme Court, to name two interested bodies, to use global estimates for the value of removing carbon emissions by, for example, raising CAFE standards for vehicles). Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time.

https://science.feedback.org/review/new-york-times-story-highlights-the-growing-number-of-extremely-hot-days-in-a-warming-world-brad-plumer-n-popovich/

1

The New York Times, by Brad Plumer, Nadja Popovich, on 2017-06-22.

"95-Degree Days: How Extreme Heat Could Spread Across the World"

This article in the New York Times is organized around maps of projected increases in extremely hot weather because of human-caused climate change. Scientists who reviewed the article indicate that climate model projections are accurately represented, and some of the impacts of hot weather (e.g. impacts on health, crop yields) are briefly summarized.See all the scientists’ annotations in contextGUEST COMMENTS: Camilo Mora, Assistant Professor,University of Hawaiʻi at Mānoa: Overall, I think this is a great article and tool. We certainly need to increase people’s understanding of this problem and this certainly helps with that. Kristie Ebi, Professor, University of Washington: The article describes projections of extreme heat days by the end of the century, providing further support for a well-known risk of climate change. The projections are based on exposure-response relationships from a period when there was generally low awareness of the risks of extreme heat. Awareness has been increasing with the frequency and intensity of heatwaves, as has implementation of heatwave early warning systems and other adaptation options, resulting in a decline in heat-related mortality in recent years in many locations. As heatwave-related mortality increases, it is difficult to imagine individuals and governments not taking action to reduce risks. Much better understanding is needed of how to motivate a proactive adaptation. The extent to which air conditioning could be an effective option in low and middle income countries will depend on how development will evolve in these countries, including electrification. The projections confirm the importance of rapid reductions in greenhouse gas emissions to avoid larger risks later in the century.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Andrew King Research fellow, University of Melbourne: The article is accurate and interesting. I think there could be more clarity around the global warming trajectories that are used here, but otherwise the article is very good. Steven Sherwood Professor, University of New South Wales: The study’s claims all appear to be based on sound, peer-reviewed research. The claims are in line with longstanding predictions and are not cherry-picked or unrepresentative, although there are uncertainties as always in any prediction. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-away: The statements quoted below are from the article; comments and replies are from the reviewers. Continued greenhouse gas emissions will cause Earth’s climate to warm, which means (in part) that extremely hot days will occur more frequently. “Global warming under Paris pledges” Andrew King Research fellow, University of Melbourne: There is a risk that some people might confuse the term “Paris pledges” with the 1.5- and 2-degree C targets that came out of the Paris Agreement. “In this scenario, countries would take some measures, but not drastic ones, to curb emissions — roughly the trajectory of the current pledges under the Paris climate agreement.” Andrew King Research fellow, University of Melbourne: The map is based on the medium-emissions trajectory of RCP4.5, which is roughly in line with the combined current pledges from the Paris Agreement. It would be useful if the article noted that this trajectory is not in line with either the 1.5- or 2-degree global warming targets from the Paris Agreement. “That’s likely to rise to a range of 137 to 200 days per year.” Andrew King Research fellow, University of Melbourne: The article doesn’t hide the fact that there is fairly high uncertainty in these projections. This helps the reader understand the confidence in the projected changes.

https://science.feedback.org/review/energy-secretary-rick-perry-incorrectly-claims-co2-not-primary-cause-climate-change/

Incorrect

CNBC, Rick Perry, 2017-06-19

Most likely the primary control knob [on climate change] is the ocean waters and this environment that we live in.

Misleading: While oscillations in the distribution of ocean temperatures are an important source of natural variability, this does not change the total amount of energy in Earth’s climate system. The increase of carbon dioxide and other greenhouse gases is the primary reason for modern global warming. Lacks specifics: It is unclear what climatic factors are or are not included in the phrase “and this environment that we live in”.

The best scientific understanding of modern climate change is better summarized by the title of a 2010 study published in the journal Science: “Atmospheric CO2: Principal Control Knob Governing Earth’s Temperature”.

No, most likely the primary control knob [on climate change] is the ocean waters and this environment that we live in.

Patrick Brown Assistant Professor, San Jose State University: If we define climate change as the increase in global temperatures that have been observed since the industrial revolution, then Secretary Perry’s statement is false. Human-caused increases in atmospheric CO2 represent the single largest cause of the Earth’s uptake of heat over that time period. The influence of various drivers of climate change on the amount of Earth heat-uptake since 1750. From IPCC (2013)1. It is true that natural changes in ocean circulations, combined with other aspects of “this environment that we live in”, can influence global temperatures from year-to-year and from decade-to-decade. Thus, these natural changes can alternatively mask or exaggerate the long-term warming trend for as long as a few decades2. However, these natural changes tend to “cancel out” in the long-run such that they cannot be responsible for the sustained warming that we have seen since the industrial revolution. 1- IPCC (2013)Summary: for Policymakers. In: Climate Change 2013: The Physical Science Basis 2- Knutson et al (2016) Prospects for a prolonged slowdown in global warming in the early 21st century, Nature Communications Agus Santoso Senior research scientist, University of New South Wales: At first impression, this is actually a not-quite-straight-forward question to answer. It is understandable that someone gives an answer like: “No, most likely the primary control knob is the ocean waters and this environment that we live in.” But such answer is also not correct. Why? First, there should be many knobs in the Earth’s climate system. It is a complex system: its various components (oceans, land, atmosphere, cryosphere) are coupled together and interact with one another. The system constantly fluctuates, and all the knobs are turning. Because it is a coupled system, turning one knob will turn another, etc. This complexity makes it hard for people to comprehend there is one single knob that controls everything. The ocean, and thus the Earth, warms and cools naturally on various time scales, even when CO2 is kept constant. For instance, from time to time more cold deep water is brought up to the surface by the strengthened Trade Winds along the equatorial Pacific. Such condition occurring during a certain year is referred to as the La Niña phenomenon, and in effect the global temperature falls. The reverse is called El Niño. Similar conditions are also seen on inter-decadal time scales—referred to as the Interdecadal Pacific Oscillation. Think of the recent “global warming hiatus” associated with a decadal La Niña-like condition1. So the Pacific Trade Winds can be considered as a knob, right? Imagine if we can control the Trade winds to prevent the Earth from warming or cooling too much. This fact alone makes it hard for certain people to comprehend that there is anything else other than the ocean system that can be considered as a knob. But of course that’s not the only thing. Consider ice cover and the albedo effect, for instance. (E.g. when there’s less sea-ice, more solar radiation is absorbed due to low albedo, warming the Earth—let’s dump more ice on planetary scale so we can reduce global warming?) So how about CO2? Atmospheric CO2 is a potent greenhouse gas and being a greenhouse gas it keeps the planet warm2. Increasing CO2 does warm the planet further, but it’s not as simple as that. We also need to consider its indirect effect: how it changes ocean and atmospheric circulations and sea-ice, glaciers, as changes in all of these then can influence the Earth’s temperature. Further, as circulation changes, weather also changes, so we need to watch out for changes in the pattern and frequency of extreme events. Because we humans as aggregate emit CO2 at a rapid rate, largely due to fossil fuel consumption, CO2 can be considered as a “primary control knob” in the sense that it is the most obvious and available knob for us to turn to influence the climate. Although we cannot directly influence other knobs such as the ocean heat pump mentioned above, we can in effect through the CO2 knob—keep in mind the background noise, i.e., natural variability, still operates. That is not saying that there are no other knobs that we can turn. Land-use is one factor that is also important, as land-use changes can affect climate. Land-use changes also affect atmospheric greenhouse gas concentration (e.g. think of all the smoke coming from burning forests for agriculture). In essence, CO2 is humans’ primary climate control knob. 1- England et al (2014) Recent intensification of wind-driven circulation in the Pacific and the ongoing warming hiatus, Nature Climate Change 2- Lacis et al (2010) Atmospheric CO2: Principal Control Knob Governing Earth’s Temperature, Science Jonathan Gregory Professor, University of Reading and UK Met Office Hadley Centre: If the ocean were the primary control for global mean surface temperature change over decades, we would expect that the ocean below the surface would get cooler while the surface gets warmer, in order to conserve energy. In fact, observations show that the subsurface ocean as well as the Earth’s surface has warmed up over the last few decades. That means the total of the energy stored has been increasing. This extra energy must have come from outside the climate system. Evaluation of the Earth energy budget using observations and models indicates that the increase in stored energy over the last few decades, mostly taken up by the ocean, is about one-third of the extra energy absorbed as a consequence of changes in the composition of the atmosphere due to human activities, predominantly emissions of carbon dioxide. If there were no ocean, the rise in surface temperature would be larger; the effect of the ocean is to mitigate the temperature rise, rather than to cause it. The other roughly two-thirds of the extra absorbed energy has been radiated back to space. Source: IPCC (2013)* IPCC (2013)Chapter 13. In: Climate Change 2013: The Physical Science Basis Shaun Lovejoy Professor, McGill University: [Taken from a review of a similar claim.] Let’s say you are given only three pieces of information: a) The annual average value of the global temperature from 1880 to 1909 b) The atmospheric CO2 concentration for each year c) The effective climate sensitivity With only this, the temperature over the 104 years between 1909 and 2013 could be incredibly well forecast (black line in the figure below), indeed to about an accuracy of ±0.22 °C (purple lines, 90% confidence limits). This tight limit includes the so-called “pause” of the early 2000s. Knowing only the CO2 therefore allows us to predict the temperature more than 100 years into the future. Given that the total change over this time was 1.1 °C, the prediction is correct to within 20%. We know that the CO2 was anthropogenic, therefore its increase was not caused by a change of temperature. We can conclude that CO2 is responsible for much of the change in temperature over the last century. Figure adapted from Lovejoy (2015), Using scaling for macroweather forecasting including the pause, Geophysical Research Letters

https://science.feedback.org/review/breitbart-misrepresents-research-58-scientific-papers-falsely-claim-disprove-human-caused-global-warming-james-delingpole/

-2

Breitbart, by James Delingpole, on 2017-06-06.

"‘Global Warming’ Is a Myth, Say 58 Scientific Papers in 2017"

In an article for Breitbart, author James Delingpole claims to provide 58 scientific papers published in 2017 that show global warming to be “a myth”. This claim is sourced entirely from a list on a blog called “No Tricks Zone”. Delingpole claims “comfort” in “know[ing] that ‘the science’ is on our side”, but he can only do so by fundamentally misrepresenting the scientists’ research. Climate Feedback reached out to authors of the scientific studies in the list of 58 papers that Delingpole claims “corroborate, independently and rigorously” his view that “‘man-made global warming’ just isn’t a thing.” So far, 29 scientists have responded to our request for comment, and all 29 have replied “No” to the question, “Do you agree with the Breitbart article that your study provides evidence against modern climate change caused by human activities?” You can read more about their reactions below.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Peter Neff Assistant Research Professor, University of Minnesota: Despite initially getting the amount of warming the planet has experienced correct, the article goes on to trivialize this global temperature increase and proceeds to provide a 101 course in logical fallacies. This article grossly misinterprets open-access scientific papers by simply looking at graphs and entirely ignoring their meaning as explained by authors in the text. Patrick Brown Assistant Professor, San Jose State University: The article describes a blog post which contains a number of cherry-picked graphs that are irrelevant to the ultimate question of how much humans have contributed to global warming over the past century. It also ascribes conclusions to numerous scientists that the scientists themselves have clearly not made. Dan Jones Physical Oceanographer, British Antarctic Survey: This piece is a logically flawed “straw man argument”. Delingpole claims to have disproven human-driven climate change, but he does not engage with how climate change actually works. Human-driven climate change is primarily about the effects of carbon dioxide on the entire climate system. When more carbon dioxide is added to the atmosphere via fossil fuel burning, more energy ultimately reaches Earth’s surface. This extra energy ends up in the ocean, atmosphere, and cryosphere (i.e., sea ice and land ice). To see the clearest fingerprints of the extra energy added to the climate system from fossil fuel burning, you have to look at the energy content of the entireclimate system over the last several decades (most of the extra energy has gone into the ocean [Levitus et al. 2012]*). Trying to disprove globalwarming in recent decades using regional, seasonal, atmosphere-only temperature trends on centuries-long timescales is very misleading. Levitus et al (2012) World ocean heat content and thermosteric sea level change (0–2000 m), 1955–2010Geophysical Research Letters Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Reviewers’ Comments: The statements quoted below are from the Breitbart article; comments and replies are from the reviewers. “Late 20th century and early 21st century global warming, they show, is neither dramatic, nor unusual, nor scary. Here … are just some of the charts to prove it.” Shaun Lovejoy Professor, McGill University: The four charts presented in the Breitbart article purport to demonstrate that the industrial epoch warming is simply a giant natural fluctuation. But it shows nothing of the sort; it is based on a complete misunderstanding of the space-time variability of the atmosphere. The article commits two common, but fundamental errors that totally invalidate its claims. The firsttwo charts are both of spatially global scale (the northern hemisphere), they illustrate the time scale error. They show northern hemisphere temperatures with millennial scale fluctuations (changes) of the order of 1°C; the so-called “medieval warming event”. Irrespective of whether these reconstructions are accurate (the global—not European—extent of the warming is the question under debate), the change occurred over time scales much longer than the 1°C warming that occurred over the last century. In the pre-industrial period, typical century long, global scale temperature fluctuations were about 0.2°C (i.e. typical century to century changes, see figure below); therefore if the temperature fluctuations followed the usual “bell-curve”, then a 1°C change in a century would have a probability of about one in 3 million of occurring naturally, the giant natural fluctuation hypothesis could easily be rejected. However, it was found that the bell curve under estimates the extreme 3% of the temperature fluctuations: extreme “black swan” events occur much more frequently than expected, yet, even when these rare extremes are taken into account, the probability of a 1°C change in a century is still less than 0.1%, it can easily be rejected1. The other fundamental error is also a scale error, but now in space rather than in time. This error is well exemplified in the fourth graph which shows data indirectly reflecting temperatures in France. Yet France is only about 0.1% of the global surface area, so that large natural fluctuations are common but are not of global significance. A common “skeptic” talking point is the fact that between 1662 and 1762, the temperature in central England increased by nearly 1 °C, i.e., about the same as the global temperature over the last century. Unfortunately for the “skeptics”, central England (greater London) is about 0.01% of the earth’s surface area so that it is not surprising that over the same period, the Northern Hemisphere temperature only increased by 0.2 °C (equal to the typical centennial change!). Finally, the third graph from China combines the two errors: the times scales are way too long and the spatial scales are way too small; it is doubly irrelevant to the question of anthropogenic global warming. Source Lovejoy (2014) 1- Lovejoy (2014) Scaling fluctuation analysis and statistical hypothesis testing of anthropogenic warming. Climate Dynamics“Here’s an unusual one from Guillet et al suggesting that there’s nothing new about wildly early or late grape harvests through the centuries Benjamin Cook Associate Research Scientist, Columbia University: The Guillet et al paper primarily uses wine grapes to look at the impact of the 1257 Samalas eruption (volcanic aerosols cool the climate, delaying grape maturation and harvest). I haven’t read the paper in the detail, but as far as I can tell they do not make any claims about recent warming or harvest trends. Contrary to the claim quoted above, our own work suggest that warming has significantly advanced wine grape harvests over western Europe1. We found, on average, that winegrape harvests have been occurring significantly earlier since 1980 (on average 10 days earlier than the 1600-1900 average). In fact, 2003 was the earliest harvest in the record by about a month. On a broader note, I want to point out that exceptional events in the paleoclimate record do not undermine the case for attributing recent warming to anthropogenic greenhouse gas emissions. We know there have been warm periods in the past, but we have quite a bit of significant independent evidence that recent warming can only be explained by invoking anthropogenic activities. [read the Dr Guillet’s comment below] 1- Cook &Wolkovich (2016) Climate change decouples drought from early wine grape harvests in France. Nature Climate Change “the mild warming of around 0.8 degrees Celsius that the planet has experienced since the middle of the 19th century” Peter Neff Assistant Research Professor, University of Minnesota: This figure [0.8°C] is generally accurate. Global average air temperature has increased by just under 1.0ºC, according to NASA Goddard Institute for Space Studies and confirmed by numerous other organizations: Source: NASA GISS However, it is quite disingenuous to suggest that warming the entire atmosphere by this amount is “mild.” Yes, it is a relatively mild adjustment on your home thermostat, increasing the temperature by less than one degree. For Americans, if your home is heated to 65ºF and you increase the temperature by 1ºF, that is equivalent to about a 0.6ºC increase. Heating the amount of air in your home is quite a different matter than heating the entire atmosphere. Just to start, the atmosphere has an approximate mass of 5 x 10^18 kg—that’s 5 quintillion kg or 11 quintillion pounds. In just over 100 years or so, we’ve increased the global air temperature thermostat by a staggering 0.8ºC—and we’re still emitting the greenhouse gases responsible for the warming. “Several of the papers note that the primary influence on warming appears to be solar activity. Few, if any, entertain the notion that carbon dioxide levels have much to do with it.” Patrick Brown Assistant Professor, San Jose State University: Many of these papers discuss the causes of temperature changes over the past several centuries or millennia. Indeed, solar activity is thought to be one of the primary drivers of the observed temperature variability over this these longer time periods. This is not the case over the past several decades. Over this recent time period we know that the Sun’s intensity has not gotten stronger because we are measuring it with satellites and we know that increasing greenhouse gasses are causing warming. We know that increasing greenhouse gasses are causing warming due to fundamental physical laws—not simply from observing that temperatures and greenhouse gas levels happen to be rising at the same time. “collaborating on studies which all corroborate, independently and rigorously, the increasingly respectable view that ‘man-made global warming’ just isn’t a thing.” Patrick Brown Assistant Professor, San Jose State University: These studies do not make this claim. Most of them are about regional (not global) temperature variations of the distant past. They generally make no claims regarding the causes of global warming over the most recent several decades nor do they make any claims about the amount of warming expected as we continue to increase greenhouse gas concentrations. Peter Neff Assistant Research Professor, University of Minnesota: This false statement is based on a list of figures taken completely out of context. For instance, No Tricks Zone [the blog Breitbart is using as a source] takes a figure from Markle et al., (2017)1 and assumes the x-axis refers to years before present. With this incorrect interpretation, it seems as though ocean temperature anomalies are very low at year 0. However, these plots show the result of simulations of idealized Dansgaard-Oeschger or Antarctic Isotope Maximum events in a general circulation model. Year 0 is simply the beginning of the simulated event and is not displaying actual modern sea surface temperature data (i.e. year 0 is not today, 0 years before present). Not only is this a red herring, it is a completely misinterpreted red herring. They also repeat the favorite Antarctic cooling cherry, taking (and altering) a figure from Mayewski et al., (2017)2 which shows Antarctic-wide climate reanalysis temperature data. As a continent (larger than the US lower-48), Antarctica is not warming. This is because much of high, dry East Antarctica is not warming. However, important areas of Antarctica, including West Antarctica which likely would show about a 0.2ºC per decade warming trend over the reanalysis period (from 1979 to present, since satellites have given good data coverage). Climate is incredibly variable around Antarctica, and also through time (large interannual variability). This is well studied, but if you only look at one graph rather than reading the research papers you will not be aware of this. See: Nicolas andBromwich (2014)New Reconstruction of Antarctic Near-Surface Temperatures: Multidecadal Trends and Reliability of Global Reanalyses. Journal of Climate Bromwich et al (2012)Central West Antarctica among the most rapidly warming regions on Earth.Nature Geoscience 1-Markle et al., (2017) Global atmospheric teleconnections during Dansgaard–Oeschger events. NatureGeoscience 2-Mayewski et al., (2017)Ice core and climate reanalysis analogs to predict Antarctic and Southern Hemisphere climate changes.Quaternary Science Reviews Response From The Authors Of The “58 Studies” Tyler Jones, Research Associate, University of Colorado The West Antarctica temperature plot that was pulled from my 2017 paper is very low resolution, and does not resolve the most recent few 100 yrs. We know from other studies that West Antarctica is currently warming faster than almost any other place on Earth. Furthermore, my paper has nothing to do with global warming or human activities. In fact, I only focus on time periods well before the Industrial Revolution. It is clear that global warming is caused predominantly by human activity. Belinda Dechnik, The University of Sydney My data does discuss sea surface temperaturein the Great Barrier Reef being slightly warmer than present during the mid-Holocene in response to natural climate variability. However, I in no way deny that the current climate is warming, and that anthropogenic effects are proving very detrimental, particularly to reef systems. This article has misunderstood my findings and in no way supports my view on climate change. I am very disturbed indeed that these people have used my article in such a way to try and discredit the serious effects of man-made climate change. Nathan Steiger, Postdoctoral Fellow, Columbia University The blog post maliciously tampered with figures from my paper, removing lines from the figures. My paper is just not relevant to the arguments about global warming. R. Scott Anderson, Professor, Northern Arizona University Although the curve shown in the Breitbart article supports our research, the specific curve cited is not our work, but comes instead from nearby tree-ring research done by Greg Wiles and his co-workers (2014). This is clearly stated in the figure caption in our article, which could have been seen if the article had been actually read. My conclusion from this is that Breitbart was not careful in its compilation, and for me this calls into question their methods for collecting data on other articles. Our conclusions are much more complex, and suggest that post-Little Ice Age warming has occurred, and has affected forests at higher elevations to a greater extent than at lower elevations. Yair Rosenthal, Professor, Rutgers University The data were taken out of context. In fact a previous article (Rosenthal et al., 20013) made the argument that the current warming, as measured by the increase in Ocean Heat Content (OHC), is a reversal of the long-term cooling trend in the preceding centuries and the rate of heat gain is substantially higher than recorded in the past. If anything, these data support global warming as manifested by the recent increase in OHC. Normunds Stivrins, Associate Professor, University of Helsinki Our article (Stivrins et al., 2017, The Holocene) focuses on other subjects than human-induced impacts (climate change). It’s sad that the blogger did not understand what this study is about, but rather took a sentence without context. Our point was that geological aspects can protect glacial ice in the ground but it starts to melt when air temperature increases—in this case when temperature started to increase above today’s temperatures. Note that this is a specific case study where exceptional environmental conditions prevail 8,400-7,400 years ago in western Latvia. Bradley Markle, PhD Candidate, University of Washington My study, and almost all I saw mentioned in the blog post, are studies of climate change in the past. My study investigates connections between different parts of the climate system during climate events that happened over 10,000 years ago. Studying climate change in the past can give context to recent climate changes. However, my study in no way investigates or tries to attribute the causes of recent climate change. It does not deal with human influences on climate. I do not argue that “global warming… is a fake artefact [sic]”. The overwhelming scientific evidence is that the climate is currently changing and that human influences, primarily releasing CO2 into the atmosphere, have a significant impact. Though, again, this is not at all addressed in my study, nor any of the ones quoted that I recognized (though I did not read them all). The blog post and Breitbart article are both misleading and inaccurate, on several levels. Ernesto Tejedor Vargas, University of Zaragoza The article Tejedor et al., 2017 is not a climate-change-denying paper. It is a paleoclimate paper showing, first, a new maximum temperature reconstruction for the last 400 years (including the current warming) and second, a new standardization method in dendrochronology to remove the non-climatic trend. The image in the post does not by any means reflect the message of the paper. That figure is the raw temperature of the CRU dataset in the region, i.e., [I would like the author of the No Tricks Zone post to] remove my name from the blog since it is not reflecting our research conclusion. David Reynolds, Postdoctoral Research Associate, Cardiff University (and co-authors) The article uses Figure 11 from Reynolds et al., 2017 without displaying the figure caption. The caption for this figure clearly states that the data shown have been detrended using a simple linear function in order to highlight the high-frequency (sub-centennial) mean annual sea surface temperature (SST) anomalies. This means we have statistically removed the long-term trend, i.e., the 20th century warming signal. The long-term trend was removed from the observational SST data as the particular proxy data being used for comparison, the marine bivalve growth increment width (GIW), does not record the low frequency change, such as the long-term warming trend. The reason the GIW chronology doesn’t record the long-term trend is because there are changes in the growth rates of the bivalves as they age (older=slower=thinner GIW). The standard procedure (e.g. Butler et al., 2009) for taking these so-called “ontogenetic effects” into account removes the ability of the GIW proxy to record long-term trends while retaining the signal of high-frequency variability. Looking at the non-detrended observational SST data (Fig 1) clearly shows there is a long-term warming trend over the 20th century in northeast Atlantic sea surface temperatures. Fig 1 — The black line shows mean annual sea surface temperatures over the North East Atlantic (50-60oN by 10-0oW). The dashed black line shows the linear trend over the 20th century. The data shown here are the raw data that were then linear detrended for use in Reynolds et al., 2017 Fig 11. Butler et al., (2009) Marine climate in the Irish Sea: analysis of a 489-year marine master chronology derived from growth increments in the shell of the clam Arctica islandica. Quaternary Science Reviews Ulrich Kotthoff, Scientist, University of Hamburg Our project covers the past ~8,000 years. The pollen-based climate reconstructions shown in our article include only two samples that cover the past 200 years. The temporal resolution of our study is thus not suited to reveal human influence on climate since the industrial revolution. Ironically, it might even be that the upper pollen samples are biased by human activity, meaning that human influence on vegetation in our research region (Southern Baltic region) might have hampered the reconstructions, e.g. by deforestation. Last not least, our data shows as well that winter temperatures did strongly increase over the past 4,000 years. One of our proxies indicates a strong temperature increase in the marine realm for the youngest sample. Interestingly, these data are not shown in the Breitbart article. Why? Our discussion of the validity of the different reconstruction methods and our interpretation of the climate signals is not taken into account at all. Matthias Thienemann, PhD Candidate, University of Cologne I do not agree with the Breitbart article that my study provides evidence against modern climate change caused by human activities. My paper deals with climate and environmental change on a larger timescale and does not allow any conclusions about current global warming. Aurel Persoiu, Emil Racovita Institute of Speleology We do not provide evidence against modern climate change caused by human activities because our record stops at AD 1860±20. Ice younger than this age has melted in the past decades: “Historical observations have shown that between AD 1863 and 1982, enhanced melting and related changes in the geometry of the ice block led to the loss of ~100 cm of ice. Based on annual ice accumulation rates derived independently of the current one (between 0.9 and 1.6 cm/year, with a mean value of ~1.3 cm/yr), we estimated an age of AD 1860 ± 20 (similar to 90 cal BP) for the top of the ice core.” The chart featured in the quoted blog article is showing the North Atlantic subtropical sea surface February temperature reconstruction of deMonecal et al (Science, 2000), not our reconstruction. We have used the deMonecal et al data in our figure 3 (panel d) and our reconstruction is in the same figure, panels c (temperature) and g (moisture source). The error in the blog article is clearly visible in the figure, where the label on the left axis reads “Atlantic winter SST”, whereas the figure itself is labeled “East central Europe”. Incidentally, the deMonecal et al data stops at 88 cal BP (similar to AD 1862). Henning Åkesson, Research Fellow, University of Bergen The Breitbart article uses a classic and flawed argument with respect to my paper, namely that “since it was warmer before (cherry-picking Norway in the mid-Holocene, around 6000 years ago), the warming we’re seeing now must be a natural phenomenon”. To infer that humans can’t be behind recent climate warming because climate changed before humans is flawed reasoning. My paper does not concern the causes of climate change, nor does the particular statement referred to in my paper (which is actually itself referring to previously published studies) provide evidence against modern climate caused by human activities. Climate in the mid-Holocene was warming due to a different configuration of Earth’s orbit relative to the sun, while warming of the last decades has been shown by overwhelming evidence (>95 % confidence in latest IPCC report) to be caused by human activities. Fatima Abrantes, Portuguese Institute for Sea and Atmosphere As anyone well informed certainly knows, an average climate warming does not at all mean that every region in the world will warm at the same rate. In fact the impact of such warmth on the atmosphere and in the surface ocean waters causes changes in the atmospheric and oceanic circulation which will have different impacts on different regions. The article on Breibart.com is so bad that the author did not even realize that the figure extracted from my paper is not my new data record but the record of the northern Spain atmospheric temperature anomaly, produced by Martín-Chivelet et al., (2011) that I have used for comparison. Indeed, my paper proves that while in the NW Iberian margin Sea Surface Temperatures (SST) during the 20th century were similar to the Medieval Warm Period ones, in the Algarve region SST shows a general increase of about 2 ºC in the last 50 years. Such results agree with both the global and regional projections that indicate this region of Europe with highest potential vulnerability in regard to current global warming (Climate, 2011). Martín-Chivelet, et al (2011)Land surface temperature changes in Northern Iberia since 4000 yr BP, based on δ13C of speleothems, Global and Planetary Change Branwen Williams, Assistant Professor, Claremont McKenna College, Pitzer College, Scripps College The seawater temperature data clearly show an increase of ~0.8C since 1860. While there are fluctuations in temperature of similar scale preceding that, the drivers of these fluctuations differ. Feng Sheng Hu, Professor, University of Illinois The graph they claimed was evidence from my article in fact was NOT even a result of [ours]. It’s a graph in an article we cited. Rob Wilson, University of St. Andrews Many of the papers are local/regional studies and will not be representative of large scale trends. One also needs to fully understand the uncertainties of these records. The latest attempts of tree-ring based northern hemisphere reconstructions clearly show a warming signal in the recent period. The constituent records may have more local complexity, but this gets averaged out/minimised when combined for large scale analyses*. A good example of what I mean at the local scale is the mention of the Rydval 2017 Scottish work. Rydval was my PhD student. The warming of Scottish summer temperatures are significant within the context of the post 1550 period. Our paper clearly states that there is great uncertainty due to less trees before this. This article does not take into account local scale variability and large scale forcing, the signal of which we see when multiple local scale records are averaged together. Stoffel et al (2015)Estimates of volcanic-induced cooling in the Northern Hemisphere over the past 1,500 yearsNature Geoscience Wilson et al (2016)Last millennium northern hemisphere summer temperatures from tree rings: Part I: The long term contextQuaternary Science Reviews Anchukaitis et al (2017)Last millennium Northern Hemisphere summer temperatures from tree rings: Part II, spatially resolved reconstructionsQuaternary Science Reviews Sébastien Guillet, University of Geneva First of all, it is important to state that the Guillet et al. paper, published in 2017 in Nature Geoscience, never claimed nor concluded that human-induced global warming was a “myth”. The paper merely aimed at reassessing the climatic impacts of the 1257 Samalas eruption on Northern Hemisphere climate using historical archives and tree-ring records. In other words, this study was not designed to answer the question of whether or not the recent warming is historically unprecedented. Let us now have a closer look at the grape harvest date (GHD) plot shown in the Breitbart article written by James Delingpole. The plot is composed of 3 GHD series. The Ile-de-France (IDF) series (purple) spans the period 1478-1977 (with several gaps due to missing observations). The IDF record was published originally by Daux et al. (2012) and Guillet et al. (2017) added a GHD for the year 1258. No GHDs are currently available for the period 1977-2017 and for the Medieval Climate Anomaly (MCA) (ca. 850-1300). Therefore the incompleteness of the IDF record is certainly not suitable for any whatsoever conclusion on whether the past few decades were unusual with respect to other periods such as the MCA. Similar statements can be made for the Alsace (orange) and Burgundy (green) records which cover the period 1700-2005 and 1354-2006 (with several missing values) respectively. We want to stress once again that GHD records shown in Guillet et al. (2017) were solely used to demonstrate that very late harvests occurred in 1258, probably as a result of the climatic anomalies (cold conditions) induced by the 1257 Samalas eruption. GHD records are now recognized as an important regional proxy for spring-summer temperature (Chuine et al., 2004; Meier et Pfister, 2007; Maurer et al., 2009; Garnier et al., 2011). Yet, as with any other proxy, the use of this archive for climate reconstructions comes with limitations and uncertainties. Several researchers have indeed shown that spring-summer temperatures are not the only factor influencing and/or determining grape harvest (Guerreau 1995, Rutishauser et al., 2007, García de Cortázar-Atauri et al., 2010). Changes in agricultural practices, the use of different grape varieties in the same region over time, as well as the political background (e.g. military conflicts, see Garnier et al., 2011) can influence harvest dates and bias the climate signal and therefore the climatic trends contained within the GHD series (García de Cortázar-Atauri et al., 2010). In summary, and given the limitations listed above, extreme caution must be taken before using the French GHD records to claim that global warming is a “massive lie”. We feel that additional studies addressing the limitations of this proxy and filling the numerous gaps existing in the available French GHD series must be carried out before drawing any definitive conclusion. References: Chuineet al (2004), Historical phenology: Grape ripening as a past climate indicator, Nature. Daux et al(2012), An open-access database of grape harvest dates for climate research: data description and quality assessment, Clim. Past. Garcia de Cortazar-Atauri et al (2010), Climate reconstructions from grape harvest dates: Methodology and uncertainties, The Holocene. Garnieret al (2011), Grapevine harvest dates in Besançon (France) between 1525 and 1847: Social outcomes or climatic evidence?, Clim. Change. Guerreau (1995), Climat et vendanges (XIVe-XIXe siècles) : révisions et compléments, Hist. Mes. Guillet et al(2017), Climate response to the Samalas volcanic eruption in 1257 revealed by proxy records, Nat. Geosci. Maurer et al(2009), BACCHUS temperature reconstruction for the period 16th to 18th centuries from Viennese and Klosterneuburg grape harvest dates, J. Geophys. Res. Meieret al (2007), Grape harvest dates as a proxy for Swiss April to August temperature reconstructions back to AD 1480, Geophys. Res. Lett. Rutishauser et al(2007), A phenology-based reconstruction of interannual changes in past spring seasons, J. Geophys. Res. BiogeosciencesJulie Richey and Jennifer Flannery, United States Geological Survey The Breitbart article, and the source it draws from, do not accurately reflect the subject matter or conclusions of our peer-reviewed, published research. Our paper, “Multi-species coral Sr/Ca-based sea-surface temperature reconstruction using Orbicella faveolata and Siderastrea siderea from the Florida Straits,” does not address global warming or its causes directly, and therefore does not, as the Breitbart article claims, “argue that the alarmist version of global warming — aka Catastrophic Anthropogenic Global Warming (CAGW) — is a fake artifact.” Our paper presents a 280-year sea surface temperature record based on the ratio of strontium to calcium in corals we sampled in the Dry Tortugas National Park. It shows that sea surface temperatures measured over many decades in the Florida Straits are variable, and that variation has been dominated for nearly the past three centuries by a natural oscillation called the Atlantic Multidecadal Oscillation. We do observe a 0.8 ºC warming trend in our record from 1970-2010 (section 3.3, page 105 of Flannery et al., 2017). Neither of these findings refutes the role of anthropogenic activity in global climate change. Anthropogenic climate change is characterized by variable climate responses across the globe. No climate record taken at a single point in space is representative of the global climate. Barbara Stenni, Associate Professor, Ca’ Foscari University of Venice Our work agrees perfectly with the results from climate models, which show that Antarctic warming should be significantly delayed relative to the rest of the planet. Furthermore, our work confirms previous work demonstrating that West Antarctica and the Antarctic Peninsula are among the fastest-warming regions on the planet. Andrea D. Tegzes and Eystein Jansen, University of Bergen Firstly, about the graphs: This is the work of Thornalley and co-authors from 2009. The datasets are based on samples from a site just south of Iceland in the northern North Atlantic (denoted by RAPiD-12-1K in Fig. 1), and not on samples from the eastern Norwegian Sea. The two graphs show reconstructed late-spring/early-summer near-surface (0-50m water depth) and sub-thermocline (approx. 100-200m water depth) ocean temperatures at this specific site. Upper-ocean temperatures at this location are particularly sensitive to changes in ocean-circulation patterns, primarily to the northeast extent of the Subpolar Gyre (SPG), and hence the degree of mixing between colder subpolar waters and warmer Atlantic waters (North Atlantic Current, NAC) (Fig. 1). The impact of ocean circulation is more pronounced at sub-thermocline depths. Near the surface, these changes are masked in part by seasonal warming. Figure 1 — The impact of changes in ocean-circulation patterns on upper-ocean temperatures south of Iceland and along the mid-Norwegian Margin. Ocean currents are marked by white arrows. Cold and warm water masses are indicated by blue and red-orange shading, respectively. Thornalley et al. (2009) used samples from the South Iceland Rise (site marked by RAPiD-12-1K), while Tegzes et al. (2017) used samples from the mid-Norwegian Margin (site marked by HA). Secondly, about the quote in the blog post (“Our sortable-silt time series show prominent multi-decadal to multi-centennial variability, but no clear long-term trend over the past 4200 years.”): Tegzes et al. (2017) investigated northward oceanic heat transport along the mid-Norwegian Margin, which is determined both by the temperature and volume of water advected northwards in the Norwegian Atlantic Slope Current (NwASC). We cannot directly reconstruct volume transport. However, by analyzing the coarseness of current-sorted deposits, we can make inferences about past variations in current speed. The sortable-silt time series, mentioned in the quote, are our current-strength proxy records from the mid-Norwegian Margin (site denoted by HA in Fig. 1). When we compared these time series with upper-ocean temperature proxy records from the same location (Andersson et al., 2003; Risebrobakken et al., 2011; Risebrobakken et al., 2003), we found either no correlation or, a seemingly counterintuitive, inverse relationship between the strength of the NwASC and the temperatures of the upper ocean at the mid-Norwegian Margin. Therefore, we concluded that, when investigating past climate, we cannot make inferences about the impact of the NwASC on regional climate solely based on its past strength. We also need independent information about the temperatures of the waters that it transported northwards from the northern North Atlantic. The authors of both papers, Thornalley et al. (2009) and Tegzes et al. (2017), aimed to broaden our understanding of ocean circulation. The coring locations (sites marked by RAPiD-12-1K and HA in Fig. 1) were chosen with that in mind. Reconstructed and measured ocean temperatures at these locations may have a large advective component, and hence should never be used to assess global warming without careful prior analysis. In addition, the sediments south of Iceland did not record the last few decades, and thus cannot be used in any argument about the modern situation. These local or regional patterns do not reflect global or hemispheric temperatures as inferred by the Breitbart article. References: Andersson et al. (2003) Late Holocene surface ocean conditions of the Norwegian Sea (Vøring Plateau). Paleoceanography. Risebrobakken et al. (2011) Early Holocene temperature variability in the Nordic Seas: The role of oceanic heat advection versus changes in orbital forcing. Paleoceanography. Risebrobakken et al. (2003) A high-resolution study of Holocene paleoclimatic and paleoceanographic changes in the Nordic Seas. Paleoceanography. Tegzes et al. (2017) Northward oceanic heat transport in the main branch of the Norwegian Atlantic Current over the late Holocene. The Holocene. Thornalley, Elderfield and McCave (2009) Holocene oscillations in temperature and salinity of the surface subpolar North Atlantic. Nature. Wenfeng Deng, Associate Research Fellow,Guangzhou Institute of Geochemistry Our results indicate that the Current Warm Period (AD 1850-present) is similar to or even warmer than the Medieval Climate Anomaly (AD 900-1300) over the western Pacific. Therefore, the Breitbart article misunderstood and overinterpreted our results and conclusions. Tomi Luoto, Adjunct Professor,University of Jyväskylä Our graph presents the relationship between temperature and precipitation (not a temperature record) and cannot be used to interpret anthropogenic climate change directly. Florin Pendea, Associate Professor,Lakehead University Orillia The claim that our paper Pendea et al. (2017) published in the Quaternary Science Reviews brings support to the notion that anthropogenic global warming doesn’t exist is completely false. The story circulated by Breitbart news represents a gross misunderstanding of the data presented in our paper. The data we present constitutes a record of millennial-scale environmental change in the North Pacific that has no relevance to the discussion around the global warming trend observed during the last 150 years in a vast number of environmental archives around the world. Guocheng Dong,State Key Laboratory of Loess and Quaternary Geology, Chinese Academy of Sciences Our paper published in The Holocene has not shown anything about human-caused global warming. I believe that misunderstanding may have occurred. Miloš Rydval, University of St. Andrews In the Rydval et al 2017 article, we clearly and repeatedlyemphasizethat there is a considerable amount of uncertainty associated with our temperature reconstruction and this generally increases further back in time and is related to, among others, data availability. This point is discussed in considerable detail in the paper and is a matter that was entirely ignored by the source cited in the Breitbart article. Thus, the cited statement: “[the reconstruction] suggests that the recent summer-time warming in Scotland is likely not unique when compared to multi-decadal warm periods observed in the 1300s, 1500s, and 1730s …” was taken out of context and misrepresented. The cited source conveniently omitted the second part of the sentence which highlights uncertainty in the earlier parts of the reconstruction and includes a cautionary statement about the interpretation of those periods. Also, it should be noted that ourstudy provides information about conditions in and around Scotland, and is therefore not a representation of the average global trends of temperature change over time, but instead representslocalscale variability. Importantly, there is nothing in our paper that in any way contradicts recent anthropogenic climate change and its causes.

https://science.feedback.org/review/breitbart-falsely-claims-58-studies-refute-human-caused-global-warming/

Inaccurate

Breitbart, James Delingpole, 2017-06-06

'Global warming' is a myth — so say 80 graphs from 58 peer-reviewed scientific papers published in 2017.

Misrepresents source: Every study author who responded explained that their work did not support the assertion that "global warming' is a myth". Read more in a full evaluation of this article...

These studies of past climate do not challenge the well-researched fact that human activities are responsible for climate change, as many of the scientists behind the studies have confirmed.

'Global warming' is a myth — so say 80 graphs from 58 peer-reviewed scientific papers published in 2017.

Patrick Brown Assistant Professor, San Jose State University: These studies do not make this claim. Most of them are about regional (not global) temperature variations of the distant past. They generally make no claims regarding the causes of global warming over the most recent several decades nor do they make any claims about the amount of warming expected as we continue to increase greenhouse gas concentrations. Peter Neff Assistant Research Professor, University of Minnesota: This false statement is based on a list of figures taken completely out of context. For instance, No Tricks Zone [the blog Breitbart is using as a source] takes a figure from Markle et al., (2017)1 and assumes the x-axis refers to years before present. With this incorrect interpretation, it seems as though ocean temperature anomalies are very low at year 0. However, these plots show the result of simulations of idealized Dansgaard-Oeschger or Antarctic Isotope Maximum events in a general circulation model. Year 0 is simply the beginning of the simulated event and is not displaying actual modern sea surface temperature data (i.e. year 0 is not today, 0 years before present). Not only is this a red herring, it is a completely misinterpreted red herring. They also repeat the favorite Antarctic cooling cherry, taking (and altering) a figure from Mayewski et al., (2017)2 which shows Antarctic-wide climate reanalysis temperature data. As a continent (larger than the US lower-48), Antarctica is not warming. This is because much of high, dry East Antarctica is not warming. However, important areas of Antarctica, including West Antarctica which likely would show about a 0.2ºC per decade warming trend over the reanalysis period (from 1979 to present, since satellites have given good data coverage). Climate is incredibly variable around Antarctica, and also through time (large interannual variability). This is well studied, but if you only look at one graph rather than reading the research papers you will not be aware of this. See: Nicolas andBromwich (2014)New Reconstruction of Antarctic Near-Surface Temperatures: Multidecadal Trends and Reliability of Global Reanalyses. Journal of Climate Bromwich et al (2012)Central West Antarctica among the most rapidly warming regions on Earth.Nature Geoscience 1-Markle et al., (2017) Global atmospheric teleconnections during Dansgaard–Oeschger events. NatureGeoscience 2-Mayewski et al., (2017)Ice core and climate reanalysis analogs to predict Antarctic and Southern Hemisphere climate changes.Quaternary Science Reviews Tyler Jones, Research Associate, University of Colorado The West Antarctica temperature plot that was pulled from my 2017 paper is very low resolution, and does not resolve the most recent few 100 yrs. We know from other studies that West Antarctica is currently warming faster than almost any other place on Earth. Furthermore, my paper has nothing to do with global warming or human activities. In fact, I only focus on time periods well before the Industrial Revolution. It is clear that global warming is caused predominantly by human activity. Belinda Dechnik, The University of Sydney My data does discuss sea surface temperaturein the Great Barrier Reef being slightly warmer than present during the mid-Holocene in response to natural climate variability. However, I in no way deny that the current climate is warming, and that anthropogenic effects are proving very detrimental, particularly to reef systems. This article has misunderstood my findings and in no way supports my view on climate change. I am very disturbed indeed that these people have used my article in such a way to try and discredit the serious effects of man-made climate change. Nathan Steiger, Postdoctoral Fellow, Columbia University The blog post [that the Breitbart article is based on] maliciously tampered with figures from my paper, removing lines from the figures. My paper is just not relevant to the arguments about global warming. Yair Rosenthal, Professor, Rutgers University The data were taken out of context. In fact a previous article (Rosenthal et al., 20013) made the argument that the current warming, as measured by the increase in Ocean Heat Content (OHC), is a reversal of the long-term cooling trend in the preceding centuries and the rate of heat gain is substantially higher than recorded in the past. If anything, these data support global warming as manifested by the recent increase in OHC. Bradley Markle, PhD Candidate, University of Washington My study, and almost all I saw mentioned in the blog post, are studies of climate change in the past. My study investigates connections between different parts of the climate system during climate events that happened over 10,000 years ago. Studying climate change in the past can give context to recent climate changes. However, my study in no way investigates or tries to attribute the causes of recent climate change. It does not deal with human influences on climate. I do not argue that “global warming… is a fake artefact [sic]”. The overwhelming scientific evidence is that the climate is currently changing and that human influences, primarily releasing CO2 into the atmosphere, have a significant impact. Though, again, this is not at all addressed in my study, nor any of the ones quoted that I recognized (though I did not read them all). The blog post and Breitbart article are both misleading and inaccurate, on several levels. David Reynolds, Postdoctoral Research Associate, Cardiff University (and co-authors) The article uses Figure 11 from Reynolds et al., 2017 without displaying the figure caption. The caption for this figure clearly states that the data shown have been detrended using a simple linear function in order to highlight the high-frequency (sub-centennial) mean annual sea surface temperature (SST) anomalies. This means we have statistically removed the long-term trend, i.e., the 20th century warming signal. The long-term trend was removed from the observational SST data as the particular proxy data being used for comparison, the marine bivalve growth increment width (GIW), does not record the low frequency change, such as the long-term warming trend. The reason the GIW chronology doesn’t record the long-term trend is because there are changes in the growth rates of the bivalves as they age (older=slower=thinner GIW). The standard procedure (e.g. Butler et al., 2009) for taking these so-called “ontogenetic effects” into account removes the ability of the GIW proxy to record long-term trends while retaining the signal of high-frequency variability. Looking at the non-detrended observational SST data (Fig 1) clearly shows there is a long-term warming trend over the 20th century in northeast Atlantic sea surface temperatures. Fig 1 — The black line shows mean annual sea surface temperatures over the North East Atlantic (50-60oN by 10-0oW). The dashed black line shows the linear trend over the 20th century. The data shown here are the raw data that were then linear detrended for use in Reynolds et al., 2017 Fig 11. Butler et al., (2009) Marine climate in the Irish Sea: analysis of a 489-year marine master chronology derived from growth increments in the shell of the clam Arctica islandica. Quaternary Science Reviews Matthias Thienemann, PhD Candidate, University of Cologne I do not agree with the Breitbart article that my study provides evidence against modern climate change caused by human activities. My paper deals with climate and environmental change on a larger timescale and does not allow any conclusions about current global warming. Florin Pendea, Associate Professor,Lakehead University Orillia The claim that our paper Pendea et al. (2017) published in the Quaternary Science Reviews brings support to the notion that anthropogenic global warming doesn’t exist is completely false. The story circulated by Breitbart news represents a gross misunderstanding of the data presented in our paper. The data we present constitutes a record of millennial-scale environmental change in the North Pacific that has no relevance to the discussion around the global warming trend observed during the last 150 years in a vast number of environmental archives around the world.

https://science.feedback.org/review/playing-semantics-misleading-breitbart-article-downplays-us-contribution-to-climate-change/

-2

Breitbart, by Thomas D. Williams, on 2017-06-05.

"WHO: United States Among Least Polluting Nations on the Planet"

This article at Breitbart argues that World Health Organization rankings of particulate matter air quality show that the United States is not one of the biggest polluters in the context of the Paris Agreement. Scientists who reviewed the article explain that this is misleading. Air quality is not an indication of national greenhouse gas emissions—and the United States is currently the second-largest emitter of carbon dioxide. This is true regardless of whether one uses the term “pollution” to describe carbon dioxide emissions.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Michael Brauer Professor, The University of British Columbia: The facts in the article are correct but the entire premise is deliberately misleading—it is correct that with respect to CONCENTRATIONS (i.e. the level is in the air) of one type of health-damaging air pollutant, the US is one of the countries with the lowest concentrations in the world. However, the Paris Accord is related to EMISSIONS (how much is released into the air) of climate-forcing pollutants and in that context the U.S. is among the countries in the world with both the highest overall emissions and the highest emissions per capita (higher than all other OECD countries). For climate change, EMISSIONS are what matters. Aimée Slangen Researcher, Royal Netherlands Institute for Sea Research (NIOZ): This whole post is based on semantics and basically one big strawman fallacy. The author is deliberately confusing air pollution from suspended particulate matter (as discussed in the WHO report) with pollution from carbon dioxide emissions (as discussed in the Reuters link and the Paris Agreement). Even though CO2 does not impact our health through “disease-causing pollutants that get into people’s lungs”, it does change our environment and the Earth’s climate, and in that sense does classify as a pollutant. Pierre Friedlingstein Professor, University of Exeter: Deliberately misleading about the role of CO2 and whether it is a pollutant or not, minimizing the role of CO2 as a greenhouse gas agent leading to climate change. Dan Jones Physical Oceanographer, British Antarctic Survey: Should we call carbon dioxide a “pollutant”? That question is relevant for policy, but either way, our choice of language does not change how physics behaves. When you add more carbon dioxide to Earth’s lower atmosphere, you get more energy at Earth’s surface. The extra energy added by human emissions of CO2 has to go somewhere; it isn’t going to just disappear. It ends up in the ocean, atmosphere, and cryosphere, affecting Earth’s climate system and putting us at risk for negative climate impacts (e.g. sea level rise, heat waves of increasing frequency and intensity, shifts in precipitation patterns). The author claims that this additional warming might actually be beneficial overall, which is inconsistent with the body of scientific literature on the topic (as always, see IPCC for summary). In short, this article makes a number of misleading statements and casually dismisses volumes of scientific evidence. Alexis Berg Research Associate, Harvard University: This article willingly confuses air pollution by particulate matter and greenhouse gas emissions. The article cherry-picks skeptic claims and out-of-context scientific evidence like deep-past CO2 atmospheric levels to try to make the case that CO2 emissions and climate change are not an issue. It tries to deny the fact that the US is a large climate change “polluter”, in the sense that it emits a lot of greenhouse gas per capita, by using the old, tired talking point that CO2 is not a pollutant, and that otherwise US air pollution is pretty low. Irrelevant and misleading.Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from the article; comments and replies are from the reviewers. 1. US cities generally do not have high concentrations of particulate matter in the air compared to other regions, but the United States currently emits more carbon dioxide than any other nation except China and is #1 in total emissions up to the present day. “Despite recent attempts to paint the United States as a major global polluter, according to the World Health Organization (WHO), the U.S. is among the cleanest nations on the planet.” Pierre Friedlingstein Professor, University of Exeter: This Breitbart article is playing with words, arguing that CO2 is not a “pollutant”. When it comes to CO2, the US is the second largest emitter after China. CO2 is a greenhouse gas, primarily responsible for climate change, inducing negative impacts on human and ecosystems. Replace the word “polluter” with “emitter” and the whole article falls apart—there is no story here. Chris Brierley Senior Lecturer, University College London: This presumes a strong link between the cleanliness of a country’s air and its own emissions. This does not necessarily hold. For example, the tiny papal state of the Vatican City is probably rather polluted (as it’s contained solely within the city of Rome). However, the vast majority of that pollution will have been emitted in Italy. “While France and other G7 countries lamented the U.S. exit from the Paris climate accord, America’s air is already cleaner than that of any other country in the G7, except Canada with its scant population.” Pierre Friedlingstein Professor, University of Exeter: The Breitbart author must know that the Paris Agreement is about climate change, not about air quality. “the WHO measures air pollution by the mean annual concentration of fine suspended particles of less than 2.5 microns in diameter. These are the particles that cause diseases of all sorts and are responsible for most deaths by air pollution. According to the WHO, exposure to particulate matter increases the risk of acute lower respiratory infection, chronic obstructive pulmonary disease, heart disease, stroke and lung cancer. The report […] found that the United States was one of the most pollution-free nations in the world.” Daniel Cohan Associate Professor, Rice University: The particulate matter (PM) discussion is essentially correct. PM is indeed thought to cause far more deaths than any other air pollutant. The United States indeed has lower PM2.5 levels than most other countries, especially when comparing cities. Most of the country outside California attains EPA’s 12 ug/m3 PM2.5 standard. “Most pollution-free” is poorly worded, since of course no populated area is ‘pollution-free’. But yes, PM2.5 levels in urban and rural areas of the United States are lower than those in corresponding areas of many other countries. The article misleads by conflating levels of air pollution with terminology like “most polluting” or “biggest polluters”. Relatively clean air quality in the United States does not negate the fact that we are the world’s second largest emitter of CO2. “With such relatively clean air throughout America, how can even reputable news agencies like Reuters continue spreading the well-worn lie that the United States is one of the ‘biggest polluters’ in the world?” Pierre Friedlingstein Professor, University of Exeter: Reuters is simply saying that in terms of CO2 emissions, China is the top emitter and the USA is second. There is no point denying this. It’s a fact, based on national fossil fuel production and consumption inventories. Whether you call CO2 “pollutant” or not is irrelevant. It is the main driver of climate change. Chris Brierley Senior Lecturer, University College London: America has the largest economy and the 3rd largest population on Earth. Even if each of its factories and people themselves emitted less than in most other countries, it would still add up to being one of the biggest polluters. Alexis Berg Research Associate, Harvard University: As the author pretends not to understand, this is the case if one considers greenhouse gas emissions as part of pollution. While China’s emissions grew tremendously over the last couple decades and it overtook the US as the largest total emitter a few years ago, the US is still one of the largest emitters per capita. In addition, historically, the US (and the EU) still own the largest share of cumulative emissions since the preindustrial era when emissions began. “While the United States must remain vigilant to keep the level of real, dangerous pollutants to a minimum, it may take some consolation in the fact that among G7 nations, it has the cleanest air of all.” Chris Brierley Senior Lecturer, University College London: Carbon dioxide is a well-mixed greenhouse gas—its concentrations are roughly 407 ppm everywhere across the globe. The national concentration bears absolutely no relevance to the country’s emissions. “The problem with this ploy is that carbon dioxide is not a pollutant and it is dishonest to say it is. CO2 is colorless, odorless and completely non-toxic. Plants depend on it to live and grow, and human beings draw some into their lungs with every breath they take to no ill effect whatsoever. Growers regularly pump CO2 into greenhouses, raising levels to three times that of the natural environment, to produce stronger, greener, healthier plants.” Pierre Friedlingstein Professor, University of Exeter: Again, the point is not “is CO2 a pollutant or not”. (I believe the Supreme Court said it is.) The point is: CO2 emissions in the atmosphere lead to climate change as CO2 is a greenhouse gas. Climate change has and will have negative impact on ecosystems (land and ocean). The author deliberately ignores this. Aimée Slangen Researcher, Royal Netherlands Institute for Sea Research (NIOZ): While the CO2 does not impact our health through “disease-causing pollutants that get into people’s lungs”, it does change our environment and the Earth’s climate, and in that sense it does classify as a pollutant. Richard Lindroth Vilas Distinguished Achievement Professor, University of Wisconsin-Madison: This statement is absolutely ridiculous. It violates the most basic, fundamental maxim of toxicology, first articulated by the Renaissance physician Paracelsus: “The dose makes the poison.” Or, “All things are poison and nothing is without poison; only the dose makes a thing not a poison.” In other words, just because a substance at one concentration is harmless does not mean it is harmless at another concentration. We don’t normally think of consumption of water as harmful to humans, but at high enough doses it will kill—and has done so. A pollutant is generally defined as a substance—artificial (synthetic) or natural—that occurs in the environment at least in part because of human activity, and that has a deleterious impact on living systems. Given that basic definition, there is no way that CO2 can not be a pollutant. It is produced by a variety of human activities, but principally burning of fossil fuels. Increases in its concentration are clearly linked to global warming, which has already, and increasingly will, negatively affect living systems, including humans. The only exit from this logic is to deny that CO2 leads to warming (in contradiction to massive scientific evidence) or to deny that warming negatively impacts living systems (again in contradiction to massive evidence). The authors use a classic rhetorical ploy to confound bits of information and draw erroneous conclusions. Yes, at low concentrations CO2 is not directly harmful to humans, and in fact is required by plants. And yes, small increases in CO2 have been shown to increase plant growth. (Some of my own work has shown such; such increases also shift the chemical composition of plant tissues, and not always for the better!). Plants grown under elevated CO2 do grow faster. To my knowledge, there is no evidence that they are “stronger” (whatever that means), and if anything, they are less green. Nor is there convincing evidence they are healthier. If anything, insects consume them more than ambient-CO2 plants. Alexis Berg Research Associate, Harvard University: This depends on the definition of “pollutant”. To the extent that CO2-induced global warming endangers human welfare and health, CO2 fits the Clean Air Act’s broad definition of “air pollutants”—that’s the reasoning behind the Supreme Court’s decision to let the EPA regulate CO2 emissions. Not that this is relevant to the definition of CO2 as a pollutant (which relies on it causing climate change), but the alleged total non-toxicity is not entirely true: there is some research* showing impairments in cognitive function test scores in people exposed to CO2 concentrations in the 950-1,000 ppm range, and even significantly worse performance when CO2 rose to 1500 and 2,500 ppm. Current atmospheric CO2 is around 400 ppm—possibly going up at least a few more hundred ppm this century without emission cuts—but concentrations greater than ~1000 ppm are often found in poorly ventilated rooms and buildings. Allen et al (2016) Associations of cognitive function scores with carbon dioxide, ventilation, and volatile organic compound exposures in office workers: a controlled exposure study of green and conventional office environments, Environmental Health Perspectives 2. Rising levels of carbon dioxide and other greenhouse gases result in climate change, which has significant negative impacts on humans and their environment. “Without human intervention, the concentration of CO2 has climbed as high as 7,000 parts per million (ppm) in prior eras, whereas at present the concentration is just over 400 ppm.” Pierre Friedlingstein Professor, University of Exeter: A CO2 concentration of 7000 ppm is a model estimate (not observations) for the Cambrian, about 500 million years ago. There are obviously no measures of temperature for that time, but estimates from models are about 10°C (18°F) warmer than present day! Not exactly reassuring news… Chris Brierley Senior Lecturer, University College London: But those worlds were rather different to those that humans inhabit. They had things like palm trees and crocodiles in the Arctic, and arguably land in the Tropics was completely sterile because of the heat. “Some experts, such as UN climate scientist Dr. Indur Goklany, have defended rising CO2 levels as a good thing for humanity. Goklany has argued that the rising level of carbon dioxide in the earth’s atmosphere ‘is currently net beneficial for both humanity and the biosphere generally.” Chris Brierley Senior Lecturer, University College London: I don’t believe that Dr. Goklany was ever employed or seconded to the UN. In fact, he would appear to be working for the climate-dismissing think tank, the Heartland Institute. Alexis Berg Research Associate, Harvard University: Technically, there is no such thing, really, as a UN climate scientist. There are climate scientists, worldwide, working for universities or national research organizations, and who contribute to the UN’s IPCC review process when it produces its report, every 7 years or so. Dr. Goklany is listed (Wikipedia) as working for the US Department of Interior as a science and technology policy analyst. His PhD is in electrical engineering, and beyond opinion pieces, he doesn’t seem to have published in the field of climate sciences. So I am not sure why his opinion is relevant at all—it goes without saying that it goes against the assessment of most of the scientific community working on climate change issues. Pierre Friedlingstein Professor, University of Exeter: Dr. Goklany is one of the very few defending that view. IPCC AR5* is very clear: “Continued emission of greenhouse gases will cause further warming and long-lasting changes in all components of the climate system, increasing the likelihood of severe, pervasive and irreversible impacts for people and ecosystems.” IPCC (2013) Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change

https://science.feedback.org/review/paris-agreement-op-ed-us-senator-ted-cruz-misrepresents-costs-benefits-reducing-greenhouse-gas-emissions/

-2

CNN, by Senator Ted Cruz, on 2017-05-29.

"Ted Cruz: Trump should withdraw from Paris climate pact"

In an op-ed published by CNN, US Senator Ted Cruz (R-TX) argues for a US withdrawal from the Paris Agreement, an international agreement with the goal of reducing greenhouse gas emissions to limit global warming. Sen. Cruz’s argument is based on claims about the climate impact of cutting greenhouse gas emissions (which he says is limited) and the economic impacts of emissions reductions (which he says are dramatic). We asked researchers to evaluate whether these claims reflected the scientific state of knowledge on these topics. The reviewers indicated that Sen. Cruz’s article cites a single report that assessed only the costs of climate actions, relying on a series of assumptions that maximized those estimated costs, and that excluded the benefits of avoided climate change and of renewable sources of energy.See all the scientists’ annotations in context REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Frank Vöhringer Dr. rer. pol, Scientist, Ecole Polytechnique Fédérale de Lausanne (EPFL): This article is a statement of opinion which uses information and pseudo-information in a biased and misleading way. For example, the economic consequences of the Paris Agreement for the USA are hugely exaggerated. Gary Yohe Professor of Economics and Environmental Studies, Wesleyan University: The claims that the Paris Accord would only produce negligible benefits is just wrong—it is the start of an iterative response that minimizes the cost of meeting any long term goal like a 2 °C target. The jobs lost claim is just hyperbole and misdirection (e.g. the demand side is costing coal jobs—a trend that started before Obama became President and that will not be reversed by Presidential Orders that open more supply). Moreover, it ignores jobs created in alternative energy design, installation, and maintenance. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from the article; comments and replies are from the reviewers. 1. The United States’ pledged emissions reductions were one portion of the global actions that would significantly limit the magnitude of future warming. “This, all while doing nothing to meaningfully decrease global temperatures.” Gary Yohe Professor of Economics and Environmental Studies, Wesleyan University: [Comment taken from an evaluation of similar statements.] The statement about the climate impact of the Paris Agreement is incorrect. The figure below, appropriated from Fawcett et al (2015)*, displays the nuances of correctly projecting the impact of the Paris Accord through 2100. Business as usual creates an emission trajectory that rapidly passes by 80 gigatons of CO2 per year by 2070; the likelihood of seeing warming less than 3 °C through 2100 along this path is 10% with a median of more than 4 °C. Abiding by the Paris Accord through 2030 and continuing its momentum through 2100 would increase that likelihood to nearly 60% with a median somewhere around 2.5 °C – a reduction of approximately 1.5 °C and not 0.2 °C. Figure— Ranges of emissions scenarios with and without the Paris Accord through 2030 and beyond. The bars on the right indicate distributions of warming through 2100, and the trajectories show a no policy case as well as a modest policy, the Paris Accord extended, and an accelerated policy case. Source: Fawcett (2015) Fawcett et al (2015) Can Paris pledges avert severe climate change?, Science Valentina Bosetti Professor, Bocconi University: The Paris Climate Agreement alone will not solve the climate change problem (meaning we need even more action, not less). It puts us on the right track, though. See the Climate Action Tracker website for details. Figure —Expected emissions projections based on NDC commitments and current policies with corresponding temperature rise (right). Source: Climate Action Tracker 2. Research shows that reducing greenhouse gas emissions does not have to result in economic harm. And importantly, the impacts of climate change come with significant costs of their own. “According to a recent National Economic Research Associates Economic Consulting study, the Paris Agreement could obliterate $3 trillion of GDP, 6.5 million industrial sector jobs and $7,000 in per capita household income from the American economy by 2040. Meeting the 2025 emissions reduction target alone could subtract $250 billion from our GDP and eliminate 2.7 million jobs. The cement, iron and steel, and petroleum refining industries could see their production cut by 21% 19%, and 11% respectively.” Kenneth Gillingham Associate Professor, Yale University: It is true that this is what the NERA study says, with many caveats. However, this statement is misleading and taken out of context. There are three reasons for this. First, and most importantly, the NERA study looked at the costs of a hypothetical set of policy actions. These may not be the actions that will be taken to comply with the Paris Agreement. One could easily model other actions with much lower costs. Second, it is only the costs that are modeled. The benefits from avoiding climate change (sea level rise, greater storm surges, greater spread of diseases, etc.) are entirely ignored. The net costs from the policies would be entirely different and likely even positive. Third, there is some cherry-picking going on here. The NERA model is known to be inflexible in how it allows for innovation to influence economic activity, and thus it tends to provide much higher cost estimates than other well-known models such as the U.S. Department of Energy’s NEMS or ICF Consulting’s IPM. The NERA model provides useful information, but it is important for it to be taken in context of model results from other models and not cherry-picked as was done here. Valentina Bosetti Professor, Bocconi University: The claim on jobs lost is totally unsubstantiated by any scientific assessment. Depending on HOW we decide to decarbonize, the effect on jobs could be either positive or negative. In general, the large investments in infrastructure required might increase jobs. This is not accounting for the totally unrelated reduction in jobs that will be most likely materialize due to robots*. Acemoglu and Restrepo (2017) Robots and Jobs: Evidence from US Labor Markets, National Bureau of Economic Research Working Paper Gary Yohe Professor of Economics and Environmental Studies, Wesleyan University: [Comment taken from an evaluation of similar statements.] The numbers he quotes are from an analysis that adds new meaning to the term “business as usual”. They look to frame their vision of the future on the basis of static behavior across major sectors of the economy; i.e., they do not allow their sectors to adapt their business operations in response to changes in their economic environment. This allows the analysis to report prices for carbon that vary by orders of magnitude across 4 major sectors and leads them to expecting investment to fall by nearly 20% at a time when increasing investment in alternative energy and new production technologies would allow them to grow their profits and support more jobs. The reported losses in jobs, GDP, and personal income are the result of these rigid assumptions and not their similarly rigid depictions of how the US would implement its plan to meet its Paris Accord target. Rather than quote a different report from a different set of experts that show economic growth in both GDP and employment (though they exist, doing so would fall into the same ordering trap as the Senator), let’s look at the recent experience in the United States. The first figure below shows that US carbon emissions have fallen by 14% since 2006, a period of time during which the unemployment rate also fell from nearly 9% to around 4.4% and the annual rate of GDP growth climbed to the historically normal range of 1.5% to 2%. The second figure shows emissions falling in California by nearly 8% since 2008 partly in response to a cap and trade program that has generated $4billion in revenue—revenue that has been used to support investment in adaptation and simultaneous expansion of the employment of less carbon intensive and/or carbon free sources of energy at scale. Over the same period, California GDP has climbed by nearly 10%. These simple economic observations contradict the Senator’s claims. Energy related carbon emissions for the United States (1992-2012) Change in California GDP, population, and GHG emissions since 2000. Source: California Air Resources Board, 2015 Bob Ward,Policy and Communications Director, London School of Economics and Political Science: The National Economic Research Associates study assumes that the United States meets the 2025 target for reducing annual emissions of greenhouse gases, which is set out in its “nationally determined contribution”, and goes on to reduce its annual emissions by 80% by 2050 compared with 1990. The authors of the study admit on pages 10-11 to making the astonishing assumption that every other country in the world ignores the targets in their nationally determined contributions and make no further efforts to reduce emissions, so that much of the calculated costs to the United States economy subsequently arise from high-carbon companies relocate or lose business to competitors in other countries. The model assumes no increase in low-carbon electricity generation over the next four decades compared with the baseline scenario, so no increase in economic growth or jobs in the low-carbon sector and no substitution of low-carbon energy for high-carbon energy—emissions reductions are achieved by imposing very high carbon prices that reduce the consumption of coal and energy. The study makes the unrealistic assumption that there will be no economic benefits to the United States from avoided impacts of climate change or co-benefits from reducing local air pollution from fossil fuels which currently contributes to the premature deaths of 200,000 Americans each year, according to a study by the Massachusetts Institute of Technology*. Overall, this is an inaccurate and misleading assessment of the cost to the United States of participating in the Paris Agreement and honouring the commitments in its nationally determined contribution—indeed, the extreme assumptions mean this a study of the costs of policy-makers attempting to achieve emissions reduction targets in some of the least cost-effective ways available. Caiazzo et al (2013) Air pollution and early deaths in the United States. Part I: Quantifying the impact of major sectors in 2005, Atmospheric Environment “Not only would these unfair standards reduce American job growth and wages[…]” Kenneth Gillingham Associate Professor, Yale University: This is possible, but hard to defend based on the evidence known today. Regulations to reduce greenhouse gases would lead to a re-optimization in the economy. For example, there would be fewer jobs at coal power plants, but more jobs in renewable energy. Whether net jobs increase or decrease depends very much on the “job intensity” of services provided in these sectors. Most estimates suggest that the job intensity is higher for renewables than for fossil fuel plants and fossil fuel extraction. See the Bureau of Labor Statistics website for very solid (but somewhat dated) evidence on green jobs in the United States. “[…]and increase monthly utility costs for hardworking families” Kenneth Gillingham Associate Professor, Yale University: This is unlikely. Other modeled analyses, such as those for the Clean Power Plan, have shown that monthly utility costs would decline under action due to increased energy efficiency investments. See EPA’s regulatory impact analysis. “The coal industry alone supplies almost one-third of America’s electric power — with an increasing amount of clean coal-burning technology becoming available.” Kenneth Gillingham Associate Professor, Yale University: This is misleading. While coal burning has become cleaner due to regulations on the air pollutants it emits, it still emits copious amounts of carbon dioxide, which is a greenhouse gas. Carbon capture and sequestration technologies have proven to be expensive and troubled (For example, see this story in The New York Times). “The Clean Power Plan, a major component of fulfilling the agreement, would spike energy costs for working and middle-class Texans by 16% by 2030, according to the Economic Reliability Council of Texas” Kenneth Gillingham Associate Professor, Yale University: This statement is incorrect. It is true that the Economic Reliability Council of Texas states that energy PRICES will increase by 16% (not costs—prices). However, with the additional energy efficiency investments the Clean Power Plan would encourage, total energy costs are modeled to decline, rather than increase (see the EPA analysis). “We simply cannot afford an agreement that puts thousands of Americans out of work[…]” Kenneth Gillingham Associate Professor, Yale University: See above for why it is misleading to say that Americans would be put out of work. Some Americans would be put out of work, while new jobs would open up for others. On net, most evidence suggests that there would be job growth, rather than a decline in jobs. “[…]increases their energy costs[…]” Kenneth Gillingham Associate Professor, Yale University: This statement is misleading. If it said “increases energy prices,” it would be correct. But it says “increases energy costs,” which is incorrect because energy efficiency is expected to reduce energy costs on net. “[…]and devastates our core industries.” Kenneth Gillingham Associate Professor, Yale University: This is simply untrue. The costs would be relatively minor in most modeled estimates and the benefits have been shown to be greater than the costs. Again, see the EPA analysis.

https://science.feedback.org/review/natural-variability-can-not-explain-modern-global-warming-heartland-institute-report-claims/

Misleading

Heartland Institute, Craig Idso, Fred Singer, Robert Carter, 2024-08-14

Neither the rate nor the magnitude of the reported late twentieth century surface warming (1979–2000) lay outside normal natural variability.

Misleading: The short timeframe given makes it more difficult to say whether something is or is not outside the bounds of natural variability. However, thorough analysis in the 2013 IPCC report concluded it was “extremely likely” (a probability of at least 95%) that humans are responsible for more than half of the warming since 1950, and likely all of it.

The warming experienced since the Industrial Revolution could not have been caused by natural factors. Human activity is primarily responsible for this (ongoing) change in climate.

Neither the rate nor the magnitude of the reported late twentieth century surface warming (1979–2000) lay outside normal natural variability.

Patrick Brown Assistant Professor, San Jose State University: The issue of whether or not a change in global temperature is outside the range of “normal natural variability” depends on the timescale being considered. It is true that some physical climate models (and some statistical climate models based on historically observed variability) indicate that it is possible for a warming episode as large as that seen from 1979-2000 to come about from unforced (internal) variability. However, when an unforced warming episode occurs, it is typically followed by an unforced cooling episode (if that wasn’t true, the climate would be fundamentally unstable and it would have run away to a snowball or hothouse state a long time ago). This means that the longer the sustained change in temperature, the less likely it is that the change could be due to “normal natural variability”. This is why the IPCC used a period almost 3 times longer in their attribution statement that “It is extremely likely that more than half of the observed increase in global average surface temperature from 1951 to 2010 was caused by the anthropogenic increase in greenhouse gas concentrations and other anthropogenic forcings together.” Overall this claim is misleading because you can always pick some subset of a forced warming/cooling episode and claim that the change in temperature over that particular time frame was not outside the range of natural variability. This would be like looking at a baseball player’s season in which he hit 100 home runs and claiming that nothing unusual was going on because it is possible for a typical player to hit 3-4 home runs in a single week. Peter deMenocal Professor, Lamont-Doherty Earth Observatory, Columbia University, and Director, Center for Climate and Life: This is a falsely constructed argument by limiting the time range to 1979 to 2000. One can cherry pick an interval and show that it’s not especially different from the past, however if one takes the full reliable record of the last 140 years the warming is unequivocal. Jeremy Fyke Postdoctoral researcher, Los Alamos National Laboratory: Exactly as deMenocal states above. Measurements over too-short intervals can be very unrepresentative of long-term trends. An extreme example: if I measured the rate of temperature change only in the evening I would very strongly claim that the Earth is always cooling. Conversely, my immediate neighbour could claim that the Earth was obviously always warming over the same period by taking measurements only in the morning. Of course, we disagree only because neither of us is measuring over a long-enough timeframe to capture an underlying temperature trend. Timothy Osborn Professor, University of East Anglia, and Director of Research, Climatic Research Unit: [This comment was made in response to a similar statement.] Taking into account uncertainties in the internal variability, in the strength of human and natural forcings and in the strength of the climate model simulations of the temperature response to these forcings, the best estimate is that all of the observed warming since 1950 is due to human influences. Because of the uncertainties, the human contribution could be larger or smaller than this, but it is “extremely unlikely” (defined by IPCC as less than 5% chance) that it is as low as only half the observed warming. IPCC (2013) Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change

https://science.feedback.org/review/lull-solar-activity-little-effect-global-temperatures-claims-global-cooling-not-based-science/

Incorrect

Heartland Institute, Craig Idso, Fred Singer, Robert Carter, 2024-08-14

Forward projections of solar cyclicity imply the next few decades may be marked by global cooling rather than warming, despite continuing CO2 emissions.

Incorrect: Even if solar activity does decline in the near future , the climate would continue to warm due to elevated greenhouse gas concentrations. Inadequate support: No reference is provided for the claim that solar activity is projected to decline beyond other Heartland Institute publications.

It is difficult to project solar activity, but research shows that even a substantial lull in solar activity would be far too weak to counteract human-caused global warming.

Forward projections of solar cyclicity imply the next few decades may be marked by global cooling rather than warming, despite continuing CO2 emissions.

Georg Feulner Senior Scientist, Potsdam Institute for Climate Impact Research (PIK): Comment taken from two prior evaluations of similar statements. While there are some indicators that future solar activity might indeed be lower, this will have little effect on global temperatures. See, for example, this RealClimate post based on Feulner and Rahmstorf (2010)1. The results have been confirmed by a number of follow-up studies2-4. While regional and seasonal effects might be larger, the expected global temperature response to a future grand solar minimum similar to the Maunder Minimum is a cooling of about 0.1°C. It should be pointed out that this cooling would occur on the background of current anthropogenic warming which is about a factor of 10 larger[…] It is also clear from these numbers that a future grand solar minimum (which would last only for a few decades anyway) would not save us from global warming, as we have shown in a scientific paper* and explained inthis RealClimate post. The marginal temperature differences between warming scenarios with and without a future Maunder Minimum is illustrated here: Figure – Rise of global temperature for two different emission scenarios (A1B, red, and A2, magenta). The dashed lines show the slightly reduced warming in case a Maunder-like solar minimum should occur during the 21st century. The blue line represents global temperature data. Source: PIK. 1- Feulner and Rahmstorf (2010) On the effect of a new grand minimum of solar activity on the future climate on Earth, Geophysical Research Letters 2- Anet et al (2013) Impact of a potential 21st century “grand solar minimum” on surface temperatures and stratospheric ozone. Geophysical Research Letters [“although the solar minimum results in a reduced global warming, it cannot compensate continuing anthropogenic impacts.“] 3- Meehl (2013) Could a future “Grand Solar Minimum” like the Maunder Minimum stop global warming? Geophysical Research Letters [“a future grand solar minimum could slow down but not stop global warming.“] 4- Jones et al (2012) What influence will future solar activity changes over the 21st century have on projected global near-surface temperature changes?Journal of Geophysical Research Atmospheres. [“the possible mitigation potential for future solar activity changes is much smaller than the known uncertainties and ranges in the future anthropogenic response.“] Peter deMenocal Professor, Lamont-Doherty Earth Observatory, Columbia University, and Director, Center for Climate and Life: Forward projections of solar variability are fraught with deep uncertainties, as exemplified by the last solar minimum. Satellite observations show this to be the weakest solar cycle in over a century. The one thing we are nearly certain of is that the years ahead will see increasing carbon dioxide concentrations in the atmosphere due to increasing emissions if nothing is done to reverse course. We know carbon dioxide and methane are greenhouse gases that trap heat in the atmosphere. Jeremy Fyke Postdoctoral researcher, Los Alamos National Laboratory: The claim that the Earth may cool in coming decades due to solar variability is incorrect (even in the word “may”). It has no bearing in any climate science, model projections, or basic physical theory. The forcing from solar variability to the heat content of the Earth system is small relative to the accelerating forcing provided by human CO2 emissions.

https://science.feedback.org/review/global-warming-not-ceased-heartland-institute-report-falsely-claims/

Inaccurate

Heartland Institute, Craig Idso, Fred Singer, Robert Carter, 2024-08-14

global warming ceased around the end of the twentieth century and was followed (since 1997) by 19 years of stable temperature

Factually Inaccurate: Global surface temperature have been the warmest on record over the past three years, in line with the global warming trend of the last several decades. Fails to grasp significance of observation: Because of natural variability, short-term periods of global surface temperatures cannot be assumed to always reflect the underlying long-term trend.

Global temperatures have continued to rise over the last few decades—notably in the oceans, which store over 90% of the excess heat trapped by the greenhouse gases humans have emitted. Over short intervals, temperatures may appear to increase slower or faster than the long term trend.

Model outputs published in successive IPCC reports since 1990 project a doubling of CO2 could cause warming of up to 6°C by 2100. Instead, global warming ceased around the end of the twentieth century and was followed (since 1997) by 19 years of stable temperature. Earth has not warmed significantly for the past 18 years despite an 8 percent increase in atmospheric CO2.

Ed Hawkins Principal Research Fellow, National Centre for Atmospheric Science: These statements are false. The IPCC has repeatedly assessed the warming due to a doubling of CO2 as between 1.5 or 2.0 °C to 4.5 °C. The warming by 2100 would be larger than this if the CO2 concentration in the atmosphere more than doubles by then. Global warming did not cease at the end of the twentieth century—the oceans, which absorb the vast majority of the additional heat trapped by greenhouse gases, have continued to warm during this time and surface temperatures have also risen, with 2014, 2015, and 2016 being the three warmest years on record. Eric Guilyardi CNRS Research Director, Université Pierre et Marie Curie & Professor, University of Reading: The range of warming for the “business as usual” scenario of the IPCC is 4 to 6 °C. A lower CO2 emissions scenario can lead to a warming which remains below 2 °C. There is no evidence to support the claim that global warming ceased. The observations compiled by the 3 main research groups (NOAA, NASA/GISS, UK Met Office/CRU) who provide estimates of surface global temperature all show continued warming. Source: NASA Natural “internal” variations occur on top of the “external” human-induced warming, leading to periods of slower warming and periods of accelerated warming. These variations are well understood by climate scientists. In the same way, Northern Hemisphere spring sees colder and warmer days (“internal” variations) superimposed onto the season’s warming due to increased “external” insolation. Human CO2 warms not only the surface but the full depth of the ocean. The natural variations exchange heat between the surface and the deeper ocean. Periods of slower surface warming correspond to periods of faster deeper ocean warming and vice-versa. Sea level height (which also reflects deeper ocean warming) has seen no slowdown, as expected from the continued CO2 emissions. Recent work has even shown an acceleration of sea level rise*. Source: NOAA Dieng et al (2017) New estimate of the current rate of sea level rise from a sea level budget approach, Geophysical Research Letters James Renwick Professor, Victoria University of Wellington: Global warming has continued uninterrupted and the last two years (2015 and 2016) are the first two to see 1 °C or more of warming compared to pre-industrial temperatures. Climate modelshave tracked this well. Daniel Swain Climate Scientist, University of California, Los Angeles: Eighteen years is generally too short an interval to quantify statistically significant climate trends; nevertheless, warming of both the Earth’s atmosphere and its oceans is apparent in observational data between 1998 and 2016. Ted Letcher Research Scientist, Cold Regions Research and Engineering Lab: Comparing the global temperature beginning at 1997 is a common trope used by some to discredit climate science. It is an intentional cherry picking of an anomalously warm year (big El Niño) to serve as the starting point. To convince yourself, start the trend at 1998, and you’ll get a much different answer.

https://science.feedback.org/review/co2-greenhouse-gas-caused-warming-past-climate-changes-notably-feedback-amplifying-factors/

Flawed reasoning

Heartland Institute, Craig Idso, Fred Singer, Robert Carter, 2024-08-14

Increases in atmospheric CO2 followed increases in temperature. Therefore, CO2 levels could not have forced temperatures to rise.

Flawed Reasoning: A lag between the initiation of past warming due to other factors and rising CO2 does not mean mean that CO2 cannot have caused temperature to increase further. Misrepresents a complex reality: CO2 has been shown to begin increasing before temperature in some instances of past climate change, but also acted as a feedback that amplified warming caused by other factors like cycles in Earth’s orbit.

Because of the physics of the transfer of electromagnetic radiation, CO2 acts as a greenhouse gas, meaning that temperatures must increase as the concentration of CO2 increases. This is true whether natural factors initiate warming (as in many past climate changes) and the release of CO2, or the warming is initiated by a release of CO2 (as humans have done).

Historically, increases in atmospheric CO2 followed increases in temperature, they did not precede them. Therefore, CO2 levels could not have forced temperatures to rise.

Christopher Colose Research Scientist, SciSpace LLC, NASA Goddard Institute for Space Studies: This is both false and irrelevant. Claims that “CO2 led temperature in the past, therefore cannot have caused it to rise” originated over a decade ago from a misrepresentation of ice core research (that itself has been subject to significant refinements in dating). It was based on the fallacy that since other factors influence climate (in this case, changes in the Earth-Sun geometry) and that the carbon cycle is affected by climate, the converse cannot be true. Of course, this is not logically coherent, and in practice is wrong since the radiative effect of CO2 is well-established. Indeed, CO2 would not be expected to fluctuate on its own 100,000 year timescale on its own, independent of the climate. In fact, more recent research* shows that CO2 still led global temperatures and the full deglacial process, unlike in older literature that examined only Antarctic sites. CO2 has also “led” global temperature on geologic timescales, and is largely responsible for how Earth’s temperature evolved over the last 50 million years. There are many ways to change the partitioning of carbon between the Earth and atmosphere, and how this happens is not relevant for the fact that if more CO2 is in the atmosphere, the planet will get warmer. Today, however, the excess source of carbon to the atmosphere is from humans. Shakun et al (2012) Global warming preceded by increasing carbon dioxide concentrations during the last deglaciation, Nature Lauren Simkins Assistant Professor, University of Virginia: This claim is flawed. Ice core records of past greenhouse gas and atmospheric temperature change1, coupled with records of ocean temperature and circulation changes2, indicate that there are complex feedbacks between earth-atmosphere-ocean changes that lead to naturally variable greenhouse gas changes. In some cases during past deglaciations, increases in CO2 have lagged methane (CH4) increases and associated atmospheric temperature rise, owing to natural processes that induce greenhouse gas release into the atmosphere. This is not the case for twentieth century and beyond human-induced atmospheric CO2 and temperature increases. Regardless of the source and cause of atmospheric CO2 increase, it will have a warming effect. Basic science does not change; CO2 is a greenhouse gas that is released into the atmosphere by burning of fossil fuels and leads to atmospheric warming. 1- Monnin et al (2001) Atmospheric CO2 Concentrations over the Last Glacial Termination, Nature 2- Skinner et al (2010) Ventilation of the Deep Southern Ocean and Deglacial CO2 Rise, Science Jeremy Fyke Postdoctoral researcher, Los Alamos National Laboratory: In the natural Earth system, CO2 release acted as a feedback of naturally-forced change (e.g. due to millennial-scale, gradual, changes in the Earth’s orbit). Thus, CO2 is clearly established as an important forcer of, for example, ice ages. This demonstrates it’s effectiveness as a radiative gas. Now, of course, the situation is flipped because humans are actively emitting CO2. This is why it is now a “forcer” rather than a “feedback”. This change in no way impacts our century-old understanding of how CO2 warms the climate.

https://science.feedback.org/review/new-york-times-series-accurately-describes-research-antarctic-ice-sheets-sea-level-rise-justin-gillis/

1.2

The New York Times, by Justin Gillis, on 2017-05-18.

"Antarctic Dispatches: Miles of ice collapsing into the sea / Racing to find answers in the ice"

This three-part article in the New York Times describes research on the outlook for Antarctica’s ice sheets and their contribution to sea level rise. Scientists who reviewed the article indicate that it is generally an accurate description of the state of research, which shows that the West Antarctic Ice Sheet (which is especially vulnerable to warming) alone has the potential to raise global sea level by several meters over the long term. However, several complex statements could be improved with additional context or more precise wording to help readers avoid misconceptions. For example, the article relies heavily on recent results from one ice sheet modeling effort that simulates higher future rates of ice melt, while other model simulations contain important differences.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Anders Damsgaard Postdoctoral Scholar, Geophysical Fluid Dynamics Laboratory, Princeton University: Generally scientifically sound, but caution should be displayed before basing discussion solely on a single modeling study, especially when it incorporates fundamentally different processes relative to other contemporary models. Benjamin Horton Professor, Earth Observatory of Singapore: Determining the rates, mechanisms, and geographic variability of sea-level change is vital to projecting future sea-level rise and managing coastal flood risks. Because the Greenland and Antarctic ice sheets have the largest potential to contribute to global mean sea-level rise under future warming, understanding their sensitivity to climate change is of particular importance. Jan Lenaerts Assistant Professor, University of Colorado, Boulder: This article is well written and contains no logical fallacies. Some statements could be clarified/quantified a bit better. Lauren Simkins Assistant Professor, University of Virginia: The Antarctic Ice Sheet has the potential to contribute significantly and rapidly to future sea-level rise. This article accurately and succinctly presents research on the processes and feedbacks that make the scientific community worried about the fate of the Antarctic Ice Sheet in a warming world. Richard Betts Professor, Met Office Hadley Centre & University of Exeter: The majority of the article is informative and a fair reflection of an important area of scientific research. It is good to inform readers of this. However, in my view, the start and end of the article and the headline give undue prominence to an highly speculative aspect of the story, i.e., the question of whether major loss of ice from Antarctica has already become unavoidable. This distinction between future, avoidable, risks and existing, unstoppable impacts is absolutely key, and while the majority of the article makes this distinction well, the emphasis in the headline and the start and end of the article are opposite to that in the main body of the article. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from the article; comments and replies are from the reviewers. 1.Studies of portions of the West Antarctic Ice Sheet—which is especially vulnerable to warming—show it’s possible that large losses of ice are already inevitable. “The acceleration is making some scientists fear that Antarctica’s ice sheet may have entered the early stages of an unstoppable disintegration.” Jeremy Fyke Postdoctoral researcher, Los Alamos National Laboratory: This is all factually true. Indeed, there is worry that a climatically-initiated dynamic disintegration is currently underway. However, there is also large uncertainty around whether this is the case. So, I would tend to classify scientific confidence on whether current mass change trends represent (in part) a true dynamical disintegration process as “low”. Jan Lenaerts Assistant Professor, University of Colorado, Boulder: This is true, but referring to West Antarctic ice sheet would be more precise. Richard Betts Professor, Met Office Hadley Centre & University of Exeter: It is clear that ongoing warming of the climate will pose major risks to the stability of ice sheets. However, this statement seems to have moved the story up a notch from what is actually written later in the article. There are two aspects to this: (1) the size of the area of concern (the whole of Antarctica rather than just parts), and (2) whether irreversible loss has already begun, as opposed to being an imminent risk. The article describes legitimate concerns that parts of the West Antarctic Ice Sheet are becoming vulnerable and hence may soon be at risk of starting an “unstoppable disintegration”, but the suggestion that this is actually already happening (and hence that major Antarctic ice loss is now avoidable) is far more speculative—as indeed the later parts of the article make clear. The phrase “entered the early stages of an unstoppable disintegration” is not the same as “becoming vulnerable to an unstoppable disintegration”, but the latter phrase would better represent what is said later in the article. “Because the collapse of vulnerable parts of the ice sheet could raise the sea level dramatically, the continued existence of the world’s great coastal cities — Miami, New York, Shanghai and many more — is tied to Antarctica’s fate.” Jan Lenaerts Assistant Professor, University of Colorado, Boulder: This is the prime motive of understanding Antarctic ice sheet dynamics, especially since the far-field location gives Antarctica relatively more weight to sea level rise along many Northern Hemisphere cities than Greenland. Lauren Simkins Assistant Professor, University of Virginia: The vulnerable parts of the ice sheet are those that resting on beds that are below sea level; therefore, the ice itself is in contact with a warming ocean. The majority of the West Antarctic and ~30% of the East Antarctic sectors of the ice sheet are grounded below sea level. “Remote as Antarctica may seem, every person in the world who gets into a car, eats a steak or boards an airplane is contributing to the emissions that put the frozen continent at risk. If those emissions continue unchecked and the world is allowed to heat up enough, scientists have no doubt that large parts of Antarctica will melt into the sea. But they do not know exactly what the trigger temperature might be, or whether the recent acceleration of the ice means that Earth has already reached it.” Jeremy Fyke Postdoctoral researcher, Los Alamos National Laboratory: This is factually true. In principle, there should be threshold in cumulative carbon emissions, beyond which the Earth system is committed to various levels of Antarctic ice loss. These thresholds have been only preliminarily explored, and are still largely unknown. And given the relatively slow response time of the Antarctic ice sheet, we may have already passes some/all of them—meaning that recent observed Antarctic changes reflect, in part, the initiation of large-scale, possibly irreversible, ice loss. “But as the ice age ended and the oceans warmed, all of them collapsed.” Timothy Osborn Professor, University of East Anglia, and Director of Research, Climatic Research Unit: “Collapse” is commonly taken to mean “fail suddenly and completely”, but in the context of ice sheets the scientific use of “collapse” can encompass much longer timescales (even multiple centuries) and it would be informative to make this clear. For example, IPCC AR5 WGI (Chapter 13 on sea level change) use it this way: “Future climate forcing could trigger such an unstable collapse, which may then continue independently of climate. This potential collapse might unfold over centuries for individual bedrock troughs in West Antarctica and sectors of East Antarctica.” Without this clarification, “collapse” may be misinterpreted to mean something happening over timescales of a single decade or much shorter timescales—especially when combined with earlier language about refugees “fleeing inland” due to a “rapid disintegration”. “The warmer water seems to be doing the most damage to a series of glaciers that flow into a region of West Antarctica called the Amundsen Sea. Satellites have identified the most rapid loss of ice there, raising a critical question: Has an unstoppable collapse of the ice sheet already begun?” Jeremy Fyke Postdoctoral researcher, Los Alamos National Laboratory: This is factually correct: this is a question that the research community is currently working hard to answer. “Already, scientists know enough to be concerned. About 120,000 years ago, before the last ice age, the planet went through a natural warm period, with temperatures similar to those expected in coming decades. The sea level was 20 to 30 feet higher than it is today, implying that the ice sheets in both Greenland and Antarctica must have partly disintegrated, a warning of what could occur in the relatively near future if the heating of the planet continues unchecked.” Timothy Osborn Professor, University of East Anglia, and Director of Research, Climatic Research Unit: Although factually correct, the information provided is not sufficient to convey the relevance of sea level during this previous warm period (the previous interglacial) to the current global warming situation. It is not directly analogous because of differences in the Earth’s orbit and the long timescale during which the ice sheet melt was exposed to the warmer temperatures. IPCC AR5 WGI Summary: for Policy Makers section B4 notes these two relevant issues: “This change in sea level occurred in the context of different orbital forcing and with high-latitude surface temperature, averaged over several thousand years, at least 2°C warmer than present”. IPCC (2013) Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change Jeremy Fyke Postdoctoral researcher, Los Alamos National Laboratory: This is factually correct. Indeed, past climate states analogous to the state which is expected to manifest in the near future, are characterized by much higher sea levels. This implies that the current Antarctic (and Greenland) ice sheet volumes are not consistent with warmer climate states. Rather, warmer climate states are consistent with smaller ice sheets. “Relatively near future” is probably a misleading statement in the text, because it implies to average people a decadal timeframe—almost certainly unrealistic for 20-30 ft of sea level rise. Anders Damsgaard Postdoctoral Scholar, Geophysical Fluid Dynamics Laboratory, Princeton University: Sea level and temperatures were higher in the previous interglacial, but the Earth climate system generally had a longer time frame to adjust to these conditions. 2. Floating ice shelves in front of Antarctic glaciers are affected by warming seawater. Ice shelves act as a stabilizing force for the ice on land, so their loss leads to greater loss of glacial ice. “The Ross shelf helps to slow the flow of land ice from Antarctica into the ocean. Compared with other parts of Antarctica, the shelf seems stable now, but computer forecasts suggest that it might be vulnerable to rapid collapse in the next few decades.” Lauren Simkins Assistant Professor, University of Virginia: Using the geological record of Antarctic Ice Sheet behavior, the Ross Ice Shelf has collapsed in the past1, likely in response to ocean and atmosphere warming. Therefore, we know that the Ross Ice Shelf, which currently protects large portion of the Antarctic Ice Sheet2, is susceptible to collapse. Yokoyama et al (2016) Widespread collapse of the Ross Ice Shelf during the late Holocene, PNAS Fürst et al (2016) The safety band of Antarctic ice shelves, Nature Climate Change “In the scientists’ worst-case computer simulations, continued global warming will cause the Ross Ice Shelf to weaken and collapse starting as early as the middle of this century.” Luke Trusel Assistant Professor, Pennsylvania State University: This collapse in the referenced work is initiated by strong surface melting causing ice shelf hydrofracture and then marine ice cliff instability. Other recent studies looking at the evolution of surface melt in Antarctica find far more modest (likely insignificant) increases in surface melt over this century, particularly over the Ross ice shelf. “Right now, the shelf works like a giant bottle-stopper that slows down ice trying to flow from the land into the sea. If it collapses, the ice could flow into the ocean more rapidly, an effect that has already happened on a much smaller scale in other areas of Antarctica. The most vulnerable parts of the West Antarctic ice sheet could raise the sea level by 10 to 15 feet, inundating many of the world’s coastal cities, though most scientists think that would take well over a century, or perhaps longer. They are worried about a possible rise of as much as six feet by the end of this century.” Timothy Osborn Professor, University of East Anglia, and Director of Research, Climatic Research Unit: This is correct but unclear. What is “perhaps longer” than “well over a century”? Given the importance of timescale for how coastal cities will respond to sea level rise, the range of possible timescales should be more explicit. IPCC AR5 WGI Chapter 13 on Sea Level Change assesses these as “sea level rise of 1 to 3 m per degree of warming is projected if the warming is sustained for several millennia (low confidence)”. IPCC (2013) Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change Margot Saher Lecturer, Bangor University, Wales, UK: Several glaciers that had previously been buttressed by the Larsen B ice shelf accelerated by a factor eight after said ice shelf disintegrated. The demise of this ice shelf lead to an increase of 27 km3 of ice loss per year*. Rignot et al (2004) Accelerated ice discharge from the Antarctic Peninsula following the collapse of Larsen B ice shelf, Geophysical Research Letters “But the story is not straightforward, and the warmer water attacking the ice has not been linked to global warming — at least not directly. The winds around the continent seem to be strengthening, stirring the ocean and bringing up a layer of warmer water that has most likely been there for centuries. Are those stronger winds tied to human-caused global warming? Some scientists think so, but others say the case is unproven. “We’re not sure because we don’t have enough data, for long enough, to separate signal from noise,” said Eric J. Steig, a scientist at the University of Washington who has studied temperature trends in Antarctica.” Jeremy Fyke Postdoctoral researcher, Los Alamos National Laboratory: This is factually correct, and an important point. In some climate analyses (such as global average air temperature), climate scientists and statisticians can (1) clearly detect a signal rising above the ‘background’ noise of natural climate variability and (2) clearly attribute this signal to human forcing (versus sun strength changes, volcanoes, cosmic rays, etc.). However, in the case of regional Antarctic climatology, this is not yet clearly the case. Particularly in the case of Antarctic oceanography, as Dr. Steig points out, this largely stems from lack of observations of sufficient length to allow for robust statistical detection/attribution of near-Antarctic ocean changes. 3. Researchers use computer model simulations to study the impacts of climate changes on ice sheets. Projecting the loss of glacial ice this century is complex, and the amount of sea level rise we can expect to see is somewhat uncertain—0.5 meters (20 inches) to as much as 1 or 2 meters (3.3-6.6 feet) given continued greenhouse gas emissions. “Recent computer forecasts suggest that if greenhouse gas emissions continue at a high level, parts of Antarctica could break up rapidly, causing the ocean to rise six feet or more by the end of this century. That is double the maximum increase that an international climate panel projected only four years ago. But those computer forecasts were described as crude even by the researchers who created them. ‘We could be decades too fast, or decades too slow,’said one of them, Robert M. DeConto of the University of Massachusetts, Amherst. ‘There are still some really big question marks about the trajectory of future climate around Antarctica.’” Benjamin Horton Professor, Earth Observatory of Singapore: Process-based predictions of sea-level rise by the International climate panel (i.e., the IPCC) are limited by uncertainties surrounding the response of the Greenland and West Antarctic ice sheets1, 2, 3, steric changes4, 5, contributions from mountain glaciers6, as well as from groundwater pumping for irrigation purposes and storage of water in reservoirs7, 8, 9. In large part because of the limitations of physical process models, IPCC AR5 does not offer “very likely” (5th to 95th percentile) sea-level projections, but concluded that “there is currently insufficient evidence to evaluate the probability of specific levels above the assessed likely range”10. The contribution from Greenland (GrIS) and Antarctic (AIS) Ice Sheet mass loss has increased since the early 1990s, comprising ~19% of the total observed rise in GMSL between 1993 and 2010 and ~40% of the total observed rise in GMSL between 2003 and 200811, 12. GrIS and AIS contributions are projected to become increasingly important over the 21st century10 and dominate sea-level rise uncertainty in the second half of the 21st century13, 14. 1- Pfeffer et al (2008) Kinematic Constraints on Glacier Contributions to 21st-Century Sea-Level Rise, Science 2- Pritchard et al (2012) Antarctic ice-sheet loss driven by basal melting of ice shelves, Nature 3- Rignot et al (2011) Acceleration of the contribution of the Greenland and Antarctic ice sheets to sea level rise, Geophysical Research Letters 4- Domingues et al (2008) Improved estimates of upper-ocean warming and multi-decadal sea-level rise, Nature 5- Marcelja (2010) The timescale and extent of thermal expansion of the global ocean due to climate change, Ocean Science 6- Raper and Braigthwaite (2009) Glacier volume response time and its links to climate and topography based on a conceptual model of glacier hypsometry, The Cryosphere 7- Konikow (2011) Contribution of global groundwater depletion since 1900 to sea-level rise, Geophysical Research Letters 8- Pokhrel et al (2012) Model estimates of sea-level change due to anthropogenic impacts on terrestrial water storage, Nature Geoscience 9- Wada et al (2012) Past and future contribution of global groundwater depletion to sea-level rise, Geophysical Research Letters 10- IPCC (2013) Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change 11- Cazenave et al (2009) Sea level budget over 2003–2008: A reevaluation from GRACE space gravimetry, satellite altimetry and Argo, Global and Planetary Change 12- Helm et al (2014) Elevation and elevation change of Greenland and Antarctica derived from CryoSat-2, The Cryosphere 13- Kopp et al (2014) Probabilistic 21st and 22nd century sea-level projections at a global network of tide-gauge sites, Earth’s Future 14- Cornford et al (2015) Century-scale simulations of the response of the West Antarctic Ice Sheet to a warming climate, The Cryosphere Jeremy Fyke Postdoctoral researcher, Los Alamos National Laboratory: I think this statement is also factually true. Indeed, recent simulations suggest that sea level rise from Antarctica could be very large. However, as is implied by the word “crude”, these state-of-the-art simulations are still lacking in important physical processes which are very difficult to implement at sufficient resolution in computer models of both the Antarctic Ice Sheet and near-Antarctic climate. So, due to these deficiencies, frankly there is still very large uncertainty regarding upcoming Antarctic change, at least as simulated by computer models. However, paleoclimate proxies have the ability to provide additional critical non-model-based constraints. Anders Damsgaard Postdoctoral Scholar, Geophysical Fluid Dynamics Laboratory, Princeton University: The “recent computer forecasts” referenced here likely refer to the numerical model developed by Rob DeConto1. Different from other ice-sheet models it includes the so-called “Marine Ice Cliff Instability”, which at present is not widely accepted in the ice-sheet modeling community. Including this instability will cause increased rates for resultant sea-level rise projections. On the other hand, DeConto’s model includes simplifications related to how ice sheet slides over the sediment at the base. This ice-sliding parameterization will generally increase ice-sheet stability and cause smaller projections of sea-level rise, as demonstrated in the Nature paper by C. Ritz et al. in 20152. There is still a lot of uncertainty regarding the physical and hydrological processes involved in ice-sheet modeling. Ideally, we prepare for the upper bounds regarding projected rates in sea-level rise, since the scientific community is still far from providing high-confidence estimates. DeConto and Pollard (2016) Contribution of Antarctica to past and future sea-level rise, Nature Ritz et al (2015) Potential sea-level rise from Antarctic ice-sheet instability constrained by observations, Nature Margot Saher Lecturer, Bangor University, Wales, UK: This is based on a combination of observations and modelling1. Observations show us several glaciers are in decline2 and ice shelves, which serve as a buttress for the glaciers, are thinning due to warmer sea water. This process is seen to be accelerating3. Where ice shelves (like Larsen B) have already vanished, glaciers in the hinterland have indeed sped up4. Numerical models predict that the changes underway now are likely to lead to a full-scale collapse of the west Antarctic Ice Sheet. 1- Joughin et al (2014) Marine Ice Sheet Collapse Potentially Under Way for the Thwaites Glacier Basin, West Antarctica, Science 2- Rignot et al (2011) Acceleration of the contribution of the Greenland and Antarctic ice sheets to sea level rise, Geophysical Research Letters 3- Paolo et al (2015) Volume loss from Antarctic ice shelves is accelerating, Science 4- Scambos et al (2004) Glacier acceleration and thinning after ice shelf collapse in the Larsen B embayment, Antarctica, Geophysical Research Letters Richard Betts Professor, Met Office Hadley Centre & University of Exeter: This reflects recent research—an important point is that this is about possible future consequences of high emissions, which are hence avoidable if emissions are lower. This is in contrast to the opening sentence and headline, which talk of “unstoppable disintegration” already in progress. “Incorporating recent advances in the understanding of how ice sheets might break apart, they found that both West Antarctica and some vulnerable parts of East Antarctica would go into an unstoppable collapse if the Earth continued to warm at a rapid pace. In their worst-case scenario, the sea level could rise by six feet by the end of this century, and the pace could pick up drastically in the 22nd century. Dr. DeConto and Dr. Pollard do not claim that this is a certainty — they acknowledge that their analysis is still rough — but they argue that the possibility should be taken seriously.” Jeremy Fyke Postdoctoral researcher, Los Alamos National Laboratory: This is factually true. I think the text is accurate in reflecting the distinct possibility of “upper-bound” Antarctic behaviour. However, note that the current “worst-case” scenario estimate is not the same as the current “most-likely” scenario estimate (in any risk assessment exercise). Anders Damsgaard Postdoctoral Scholar, Geophysical Fluid Dynamics Laboratory, Princeton University: Related to my earlier comment, the relevance of the “Marine Ice Cliff Instability” is still very unclear, and not generally accepted in the ice-sheet modeling community. DeConto and Pollard’s sea-level estimates certainly fall in the high end of sea-level rise projections. However, other processes such as non-linearities in melt or basal sliding may provide similar high-end estimates. “But some research suggests that a catastrophe might not yet be inevitable. In a study last year, Robert M. DeConto of the University of Massachusetts, Amherst, and David Pollard of Pennsylvania State University used their computer model to predict what would happen if emissions were reduced sharply over the next few decades, in line with international climate goals. Under the most ambitious scenarios, they found a strong likelihood that Antarctica would remain fairly stable.” Richard Betts Professor, Met Office Hadley Centre & University of Exeter: To my mind, the way this is written gives the impression that the DeConto and Pollard study is the outlier and that a substantial body of research suggest that a catastrophe is already inevitable—however, the article has not actually given any details of any such research, it only raised the possibility of unstoppable disintegration as a research question. It would be far more accurate to say that the vast majority of research does not suggest that a catastrophe is inevitable.

https://science.feedback.org/review/heartland-institute-reports-claim-climate-models-sensitive-co2-not-reflect-evidence/

Incorrect

Heartland Institute, Craig Idso, Fred Singer, Robert Carter, 2024-08-14

[climate models] systematically over-estimate the sensitivity of climate to carbon dioxide ... and modelers exclude forcings and feedbacks that run counter to their mission

Unsupported: There is no evidence that climate models systematically overestimate the climate’s sensitivity to CO2. Rather, independent lines of research produces sensitivity estimates consistent with models. Misrepresents the scientific process: Through research, scientists improve their understanding of the climate system, and this understanding is used to refine climate models as useful scientific tools. Science does not have a “mission” to reach a predetermined conclusion.

Climate models are based on physical processes and our understanding of how the climate system works. Their sensitivity to CO2 is in line with estimates based on modern observations and records of past climate changes.

GCMs systematically over-estimate the sensitivity of climate to carbon dioxide (CO2), many known forcings and feedbacks are poorly modeled, and modelers exclude forcings and feedbacks that run counter to their mission to find a human influence on climate.

Reto Knutti Professor, ETH Zürich: The statement that climate models overestimate the warming in response to CO2 is incorrect; it is based on either too short time periods that are dominated by natural variability, by the comparison of models with datasets that do not have global coverage, by comparing to models that were run many years ago with emissions and forcings that differed from what actually happened, by the use of oversimplified energy balance models1, or a combination of it. Recent studies have shown that once the changes in climate feedbacks over time2, datasets with full coverage are considered3 and all forcings are considered, the agreement between predicted and observed warming is excellent, even over the recent hiatus period4. It is remarkable that even projections made decades ago with climate models that were much simpler (and were running on computers that were likely slower than a mobile phone today) were quite accurate5,6,7. 1- Knutti and Rugenstein (2015) Feedbacks, climate sensitivity and the limits of linear models, Philosophical Transactions of the Royal Society A 2- Armour (2017) Energy budget constraints on climate sensitivity in light of inconstant climate feedbacks, Nature Climate Change 3- Richardson et al (2016) Reconciled climate response estimates from climate models and the energy budget of Earth, Nature Climate Change 4- Medhaug et al (2017) Reconciling controversies about the ‘global warming hiatus’, Nature 5- Stouffer and Manabe (2017) Assessing temperature pattern projections made in 1989, Nature Climate Change 6- Fischer and Knutti (2016) Observed heavy precipitation increase confirms theory and early models, Nature Climate Change 7- Allen et al (2013) Test of a decadal climate forecast, Nature Geoscience Katrin Meissner Professor, University of New South Wales: False. Climate Sensitivity has been assessed by the community based on recent observations and proxy data from past climates. Climate models fall within this range of sensitivity. Some recent publications point to an increase in sensitivity with warmer temperatures*. Paleosens Project Members (2013) Making sense of palaeoclimate sensitivity, Nature Meraner et al (2013) Robust increase in equilibrium climate sensitivity under global warming,Geophysical Research Letters Zeebe (2013) Time-dependent climate sensitivity and the legacy of anthropogenic greenhouse gas emissions,Proceedings of the National Academy of Sciences Patrick Brown Assistant Professor, San Jose State University: This argument reached a peak in popularity around 2012/2013 when the “hiatus” was still ongoing (i.e. when the divergence between observed and modeled global temperature was at its largest). Even then, however, it was shown that you cannot conclude much about sensitivity to CO2 from such short-term fluctuations1. Similarly, Brown et al. (2015)2 showed that decade-long periods without warming are to be expected and that there was/is a 70% chance of seeing at least one 11-year period with no warming between the years of 1993-2050 under a “middle of the road” emissions scenario. Since then, observed warming has surged and, as of 2016, observations are warmer than the average prediction from climate models (see figures below). 1- Marotzke and Forster (2015) Forcing, feedback and internal variability in global temperature trends, Nature 2- Brown et al (2015) Comparing the model-simulated global warming signal to observations using empirical estimates of unforced noise, Scientific Reports Figure –Modeled global surface temperature(RCP 4.5 emissions scenario) compared toobserved temperature (NASA GISS). Source Figure – Updated version of IPCC AR5 Figure 11.25a, showing observations and the CMIP5 model projections relative to 1986-2005. The black lines represent observational datasets (HadCRUT4.5, Cowtan & Way, NASA GISTEMP, NOAA GlobalTemp, BEST). Source

https://science.feedback.org/review/alaskas-vicious-cycle-warming-tundra-spews-co2-speeding-up-warming-joe-romm-think-progress/

0.3

Think Progress, by Joe Romm, on 2017-05-16.

"The ‘ancient carbon’ of Alaska’s tundras is being released, starting a vicious warming cycle"

This article at ThinkProgress by Joe Romm describes a study of carbon dioxide released from warming Alaskan tundra in recent years. While the article correctly notes the study’s conclusions, it also includes some language that is imprecise or extends beyond the contents of the study. Scientists who reviewed the story found that the article’s headline, in particular, carries a tone that exaggerates the study’s conclusions. One of the study’s authors also clarified that a personal quote used in the story (taken from a radio interview) requires context for clarity.See all the scientists’ annotations in contextUPDATE (19 May 2017): The ThinkProgress article has been edited, clarifying some of the statements highlighted here, including the title of the piece. Read moreREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Charles Koven Staff Scientist, Lawrence Berkeley National Lab: The writing is a bit over the top, but factually correct in general. The main weakness is in linking the solidly evidence-based observed changes from the Commane et al paper with much more speculative links such as the Siberian methane bubbles. Pierre Friedlingstein Professor, University of Exeter: The article departs significantly from the PNAS study it aims to cover. It’s catastrophic tone is not really supported by the study. David Archer Professor, University of Chicago: It’s true that Arctic permafrost contains lots of carbon and that this is vulnerable to decomposition in the coming few centuries. My only caveat to the reader would be that the amount of methane from the Arctic, and even the amount of CO2, are today much smaller than anthropogenic sources of those gases. The largest source of methane in the Arctic is the fossil fuel industry, but we never hear that. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-away: The statements quoted below are from the article; comments and replies are from the reviewers. Warming of the Arctic leads to thawing permafrost, which releases carbon that amplifies the warming—but this is not a runaway feedback. “The ‘ancient carbon’ of Alaska’s tundras is being released, starting a vicious warming cycle ‘This is ancient carbon, thousands and millions of years old.’ It’s being released ‘much earlier than we thought.” Pierre Friedlingstein Professor, University of Exeter: This is an interesting headline and quote. The article in PNAS uses atmospheric measurements of CO2 to derive sources and sinks from tundra and boreal forests. The study does not say that “this is ancient carbon, thousands and millions year old”… It could be, but there is no evidence for this in the paper. The paper only shows that atmospheric measurements indicate that Alaskan ecosystems have been a source of carbon in recent years (2012 to 2014). Charles Koven Staff Scientist, Lawrence Berkeley National Lab: Most of the carbon in the permafrost pool is thousands to tens of thousands year old at the oldest, rather than millions. “The Alaskan tundra is warming so quickly it has become a net emitter of carbon dioxide ahead of schedule, a new study finds” Pierre Friedlingstein Professor, University of Exeter: The study doesn’t really say that.The PNAS study itself focused on 3 years (2012-2014) for which aircraft measurements were taken from April to November, and finds that Alaskan tundra was a source of carbon for 2 of these 3 years (2012 is a small sink). Then these flux estimates are compared to data from CMIP5 models for those particular years. However, the PNAS paper does not assess when these CMIP5 models become sources of CO2. One would need to see long time series of the CMIP5 models, along with longer time series of aircraft measurements and inferred carbon fluxes to estimate when each turn from sink to sources. Because it’s getting warmer, there’s more CO2 coming out which means it’s going to get warmer which means there’s more CO2 coming out[…] And it will just run away with itself.” Pierre Friedlingstein Professor, University of Exeter: This is a simplistic description of a positive feedback. Yes, warming would lead to release of carbon from soils and permafrost, and this would lead to more warming, hence more carbon loss. But in no way would this lead to a runaway feedback. Say a warming of 1°C led to a release of carbon from soils that induces an additional warming of 0.1°C (that’s quite a large positive feedback: 10% of the initial perturbation). This additional 0.1°C would lead to an additional release of carbon, inducing an additional warming of 0.01°C, which will lead to more carbon released and an additional 0.001°C warming, etc… Ultimately, warming will be 1.111…°C—larger than the initial warming of 1°C but quite far from a runaway scenario. RóisínCommane,Research Associate, Harvard School of Engineering & Applied Sciences:(Dr Commane is the first author of the scientific study discussed in the ThinkProgress article) I spoke with Henry Fountain (New York Times), Chris Mooney (Washington Post), Oli Milman (Guardian), and Bob Berwyn (Inside Climate News) about the PNAS paper and I think they all did a great job condensing my attempts at communicating the message of the paper. The radio chat I did with a local NPR station in Juneau, AK (which I think is the source of this article) was probably the least comprehensive attempt—I tried to make things as simple as possible and didn’t realize that the quote would sound so off when taken outside of that context. I think the written articles better conveyed the essence of the paper compared to what I tried to say in the radio piece. “Melting permafrost can release not just CO2, but also methane, a much stronger heat-trapping gas.” Charles Koven Staff Scientist, Lawrence Berkeley National Lab: “Thawing” is a more accurate description than “melting” for what happens to frozen soil when you warm it. “‘We find that Alaska, overall, was a net source of carbon to the atmosphere during 2012–2014,’ the study concludes. Data from NOAA’s Barrow Alaska station ‘indicate that October through December emissions of CO2 from surrounding tundra increased by 73 percent since 1975, supporting the view that rising temperatures have made Arctic ecosystems a net source of CO2.’” Charles Koven Staff Scientist, Lawrence Berkeley National Lab: That’s a very accurate description of the study. Quite different from the headline. UPDATE (19 May 2017): Here is the list of statements that have been modified from the original version of the ThinkProgress article: UPDATE (21 May 2017): We have edited our review summary for precision. While it initially read “it also includes some language that is misleading”, we changed the word “misleading” to “imprecise”, which better describes the issue scientists had with this piece—some sloppiness in the precision of concepts used.

https://science.feedback.org/review/heartland-institute-report-incorrectly-claims-no-evidence-human-impacts-melting-ice/

Incorrect

Heartland Institute, Craig Idso, Fred Singer, Robert Carter, 2024-08-14

Melting of Arctic sea ice and polar icecaps is not occurring at ‘unnatural’ rates and does not constitute evidence of a human impact on the climate.

Incorrect: Observed Arctic sea ice loss, and mass loss from the Greenland and Antarctic ice sheets, is not explained by natural variability alone. Research indicates that human activity has made a significant contribution to the loss of glacial ice and Arctic sea ice.

The rapid loss of glacial ice and Arctic sea ice cover is consistent with and most likely due to human impact on the climate system.

Melting of Arctic sea ice and polar icecaps is not occurring at ‘unnatural’ rates and does not constitute evidence of a human impact on the climate.

Jan Lenaerts Assistant Professor, University of Colorado, Boulder: This is a mostly false statement. The correct part is the East Antarctic ice sheet is close to mass balance1, 2and that the recent changes in Antarctic sea ice cover are explained by natural variability3, 4. The statement is definitely false for Arctic sea ice, which is decreasing dramatically since the 1990s as a response to human greenhouse gas emissions. In fact, there is a direct and linear relation between CO2 emitted and sea ice decline: each metric ton CO2 emitted leads to a 3 m2 loss of Arctic sea ice5. The current loss of sea ice falls outside of natural variability and has been unprecedented in at least the last 1,450 years6. West Antarctic mass loss has been rapidly increasing since the 1990s2. Glacial retreat in the Amundsen Sea region, the main driver of this mass loss, appears to have started already in the early 20th century7. The rate of retreat is rapid and widespread8, with no mechanism for future stabilisation9. Current ice sheet mass loss contributes significantly (almost 40%10) to observed 21st century sea level rise. Until 2016, Arctic sea ice loss has dominated over slight Antarctic sea ice gain. In 2016 and 2017, Antarctic sea ice has been in decline as well, and reasons for this are currently under study. 1- Shepherd et al (2012) A Reconciled Estimate of Ice-Sheet Mass Balance, Science 2- Gardner et al (2017) Increased West Antarctic ice discharge and East Antarctic stability over the last seven years, The Cryosphere Discussions 3- Turner et al (2016) Antarctic sea ice increase consistent with intrinsic variability of the Amundsen Sea Low, Climate Dynamics 4- Meehl et al (2016) Antarctic sea-ice expansion between 2000 and 2014 driven by tropical Pacific decadal climate variability, Nature Geoscience 5- Notz and Stroeve (2016) Observed Arctic sea-ice loss directly follows anthropogenic CO2 emission, Science 6- Kinnard et al (2011) Reconstructed changes in Arctic sea ice over the past 1,450 years, Nature 7- Smith et al (2017) Sub-ice-shelf sediments record history of twentieth-century retreat of Pine Island Glacier, Nature 8- Rignot et al (2014) Widespread, rapid grounding line retreat of Pine Island, Thwaites, Smith, and Kohler glaciers, West Antarctica, from 1992 to 2011, Geophysical Research Letters 9- Joughin et al (2014) Marine ice sheet collapse potentially under way for the Thwaites Glacier Basin, West Antarctica, Science 10- Rietbroek et al (2016) Revisiting the contemporary sea-level budget on global and regional scales, PNAS Mouginot et al (2014) Sustained increase in ice discharge from the Amundsen Sea Embayment, West Antarctica, from 1973 to 2013, Geophysical Research Letters Jeremy Fyke Postdoctoral researcher, Los Alamos National Laboratory: This is demonstrably false, and indicates an ignorance of a large body of existing and easy-to-access literature, based on a wide range of independent direct observations and modeling. Both ice sheets (Greenland and Antarctica) are exhibiting mass loss, including collapse of features such as large ice shelves that have been present for millennia. Negative Arctic sea ice trends are clearly emerging from the background of natural variability. Antarctic sea ice, just this year, exhibited an unprecedented decrease, well outside of established recent natural variability windows. Peter deMenocal Professor, Lamont-Doherty Earth Observatory, Columbia University, and Director, Center for Climate and Life: The Arctic is a canary in the coal mine, and the rapid changes there reflect the telltale polar amplification signature of increased greenhouse gas forcing. The rates of Arctic sea ice retreat are unprecedented compared to earlier decades and this is one of the fastest moving systems on the planet. Both polar ice caps are losing mass as shown by GRACE satellite data. A recent study* suggests that as much as 60 % of the observed loss in late-summer Arctic sea ice extent could have been caused by changes in atmospheric circulation patterns – i.e., natural causes. Natural factors can only explain a part of the observed losses, and multiple studies (reviewed in the latest IPCC report) have shown that it is not possible to explain the observed losses without considering non-natural factors. Ding et al (2017) Influence of high-latitude atmospheric circulation changes on summertime Arctic sea ice. Nature Climate Change Jennifer Francis Senior Scientist, Woods Hole Research Center: The extent of Arctic sea ice is far lower than at any time in the past 1450 years (Kinnard et al 2011), and there is no viable explanation for its disappearance other than the rapid increase in heat-trapping greenhouse gases owing to human activities. Kinnard et al (2011) Reconstructed changes in Arctic sea ice over the past 1,450 years, Nature

https://science.feedback.org/review/global-quackery-earth-not-warmed-past-19-years-new-study-finds-joseph-curl-the-daily-wire/

-2

The Daily Wire, by Joseph Curl, on 2017-05-08.

"Global Quackery: Earth Has Not Warmed For Past 19 Years, New Study Finds"

The title of this Daily Wire article inaccurately claims that global temperature has not warmed over the past 19 years—in direct contradiction with observations—and the article provides no evidence in support of this bold claim. The article relies, for its first section, on a Telegraph article (analyzed separately here) that is flawed and itself based on claims from a blog post referring to data from the Danish Meteorological Institute (DMI). But DMI scientists explain that the article “fundamentally misrepresents both our research and the operational data products we provide”. The second section quotes an article in the UK tabloid Daily Star. It claims that an imminent ice age is coming, based on a misrepresentation of the Sun’s influence on the climate that we have already covered in an earlier Climate Feedback review: In that review, Prof. Michael Lockwood explained, “The whole argument rests on the incorrect myth that the Maunder minimum caused a ‘mini ice age’ and uses that name to draw specious implications and conclusions.” Georg Feulner also noted that “the scientists mentioned in the article have not predicted a ‘mini ice-age’, but an extended period of low solar activity similar to the 17th-century Maunder Minimum. The Maunder Minimum falls into a more extended period of somewhat cooler climate conditions termed the ‘Little Ice Age’ (although this was no true ‘ice age’). It has thus become rather fashionable to claim that the ‘Little Ice Age’ was caused by low solar activity, but this is not what the science says.”See all the scientists’ annotations in context This is part of a series of reviews of 2017’s most popular climate stories on social media.UPDATE (16 May 2017): Following this analysis, the Daily Wire edited its article. Most notably, a statement describing the misleading claims from the Telegraph article as “findings of the DMI” has been removed. However, the misleading claims in the article generally stand uncorrected. Read moreREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. William Anderegg Associate Professor, University of Utah: The article is full of misleading claims, factual inaccuracies, and lack of documentation for many of its claims. Georg Feulner Senior Scientist, Potsdam Institute for Climate Impact Research (PIK): The article contains major inaccuracies and gives a highly biased viewpoint not supported by scientific evidence. Daniel Swain Climate Scientist, University of California, Los Angeles: While there are relatively few quantitative (and scientifically assessable) claims in this piece, those that are present are categorically false. This piece draws heavily upon a recent article in The Telegraph that itself is filled with fundamental factual errors and willful misinterpretation of data. Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: The article contains little to no rational treatment of observational data, but relies on heavily biased secondhand interpretation. It has been written by someone who had no intention of researching the truthfulness of arguments that others have made, and merely reproduces their mistruths with added inflammatory language and chiding outrage. It rehashes logically-flawed and cherry-picked arguments from other articles and repeats them verbatim without questioning their authenticity. The article also rallies emotively against ‘Global Quackery’ from thousands of qualified climate scientists of all political persuasions, but then cites factually-inaccurate statements from the CEO of a dubious company as opinions of a ‘scientist’ and ‘expert’, without any question of their integrity. Even the title is based on a lie. There is no ‘study’ that finds static temperatures for 19-years. This article is based on a newspaper article that makes this false statement based in turn on a blog post. This blog post in turn willfully misinterprets data that has been made publicly-available from the Danish Meteorological Institute. In no point along this production line of mistruths was anything like a peer reviewed study involved.Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from the article; comments and replies are from the reviewers. 1. There is a long-term warming trend at both the global scale and in the Arctic, which experienced its second-warmest winter on record in 2016/2017. “ever since December temperatures in the Arctic have consistently been lower than minus 20 C” Daniel Swain Climate Scientist, University of California, Los Angeles: It is indeed true that the Arctic is cold in winter—it’s hard to argue with that. But this statement belies the fact that winter 2017 was actually extraordinarily warm by historical standards, and second only to the record-shattering warmth observed just last year (in 2016). The attached plot, created by Zachary Labe and available at http://sites.uci.edu/zlabe/arctic-temperatures, shows that the -20 °C temperatures this winter are nearly 10 °C degrees above the long-term average of -30 °C! Therefore, the fact that temperatures were -20 °C this winter in the Arctic is actually a testament to just how much the Arctic has warmed in recent years. Ruth Mottram, Martin Stendel, Peter Langen, Danish Meteorological Institute This statement is both wrong and misleading. Firstly, most of the Arctic has in fact been consistently warmer than -20 °C this winter. For the period 1 December 2016 to 20 April 2017, the average temperature was above -20 °C everywhere in the central Arctic except north of Greenland and the Canadian Archipelago. Over the Greenland Ice Sheet and in Eastern Siberia (and only there), the temperature was below -25 °C. Secondly, it should not be a surprise that the Arctic is very cold in winter (a period with little to no sunlight). It is much fairer to consider the difference between this winter and the average winter temperatures. Compared to our baseline of 2004-2013 everywhere in the Arctic region was at least 4 °C warmer than the average of 2004-2013 (in itself a warmer baseline period than the 1958-2002 baseline used elsewhere). Around Svalbard, it was about 4.5 °C warmer than average and in Northern Greenland, including Kap Morris Jesup, the world’s northernmost weather station (where a record +3 °C temperature was recorded on one day in February), Ellesmere Island in northeastern Canada, and large parts of eastern Siberia this winter were more than 5 °C warmer than the average as you can see below: Figure: Left, Average temperature over the Arctic for the period December 2016 to April 2017; Right, Deviation of temperature for the period December 2016 to April 2017 from the average 2004-2013.This makes the winter 2016/2017 the second warmest on record in the Arctic (after winter 2015-16), according to the European Copernicus climate service.“record temperatures brought in 2016 by an exceptionally strong El Niño” Andrew King Research fellow, University of Melbourne: Last year the annual global temperature was about 1.1 °C above a late-19th century baseline but only about 0.1°C of this was due to the El Niño—the other 1 °C is due to human influences. So while the record occurred in 2016 due to El Niño, most of the anomaly was due to climate change. “the satellites now show that in recent months global temperatures have plummeted by more that [sic] 0.6 degrees” Daniel Swain Climate Scientist, University of California, Los Angeles: El Niño events do indeed elevate global temperatures temporarily, and this is partly why global temperatures in 2016 were so extreme. But as the attached plot from NASA GISS shows, temperatures so far in 2017 have still been extraordinarily warm in a historical context, and in fact would have been record-breaking if not for the large temperature spike that occurred in 2016. In any case, it is not scientifically meaningful to measure global temperature “trends” over a two year period; the large and statistically significant long-term warming signal overwhelms short-term variations on multi-decadal timescales. William Anderegg Associate Professor, University of Utah: While true (and not necessarily in agreement with the more robust thermometer records for this period, this has no bearing on the long-term climate trend, which is driven by human emissions of greenhouse gases. It is misleading and a logical fallacy to claim this says anything about climate change, which is the long-term change in temperatures. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: While temperatures have declined modestly from the peak of the El Niño event, this is expected behavior, particularly in satellite records where El Niño is amplified. However, temperatures in January through April are quite above average to-date, and while we may not set a record temperature in 2017 compared to 2016, it will very likely be the second warmest year on record (at least on the surface). Through present there is no sign of any sort of pause or slowdown in any of the surface records or one of the two satellite records (the RSS groups latest version 4 record). The only record showing a continued pause is the one produced by the University of Alabama, Huntsville (the UAH record). The differences between these records and their causes is an area of active research, though we have strong reason to suspect that the surface record is quite accurate. “This means the global temperature trend has now shown no further warming for 19 years” Andrew King Research fellow, University of Melbourne: This is both cherry-picking of the data (starting with 1998), and not correct anyway. William Anderegg Associate Professor, University of Utah: This is blatantly false. Examine the trend here: Furthermore, a short time period of a few months in 2017 cannot say anything whatsoever about the long-term change in climate. Andreas Schmittner Associate Professor, Oregon State University: This statement is false. Global temperatures continue their long-term warming trend. 2. Warming in the Arctic is causing changes to the cryosphere: both sea ice and land ice (on Greenland) have been melting faster in recent years. “Arctic sea ice is thicker than ever” Alek Petty Postdoctoral associate, NASA Goddard Space Flight Center: PIOMAS (a model constrained by surface temp observations) shows the ice volume tracking lower than ever for this time of the year. Most recent direct observations show the sea ice is still a lot thinner than it was in previous decades. Georg Feulner Senior Scientist, Potsdam Institute for Climate Impact Research (PIK): This is wrong. Arctic sea-ice thickness in 2017 is actually at its lowest values compared to earlier years for which we have sufficient data coverage, see: “In April the extent of Arctic sea ice was back to where it was in April 13 years ago” Ed Hawkins Principal Research Fellow, National Centre for Atmospheric Science: In the NSIDC dataset, April 2017 was actually the equal of the lowest Northern Hemisphere extent on record (tied with 2016 on 13.83 M km2). Ruth Mottram, Martin Stendel, Peter Langen, Danish Meteorological Institute This statement is misleading. Arctic sea ice extent in April was significantly lower than the long-term average—but varies substantially from day to day and year to year as processes such as wind and waves and short-term weather variability have a substantial effect on sea ice extent, particularly at this time of year. However, over the long term since 1979, the April sea ice extent has declined by around 3% per decade, at other times of the year the decline is even more marked. This is an example of cherry-picking dates in order to try and state that the sea ice is recovering (it’s not). It also confuses climate variability with trends over short periods. “Furthermore, whereas in 2008 most of the ice was extremely thin, this year most has been at least two metres thick.” Daniel Swain Climate Scientist, University of California, Los Angeles: Arctic sea ice volume has actually exhibited record thinness so far during 2017—beating the previous record years of 2012/2016 by a wide margin. Another nice visualization by Zachary Labe illustrates this quite clearly: “Whereas in 2008 most of the ice was extremely thin, this year most has been at least two metres thick.” Ruth Mottram, Martin Stendel, Peter Langen, Danish Meteorological Institute This is a misleading statement, as “extremely thin” is not defined and what is also not stated is that there were also substantial areas of much thicker ice in 2008. If we look at the total ice volume, which averages these effects out, on 1st May 2017 it was about 6% lower than the ice volume for the same date in 2008 according to the operational ocean and sea ice model. Again, in addition to air and ocean temperature, ice thickness depends on winds and ocean currents and shows large variations from year to year so choosing two years arbitrarily is misleading without considering the long term trend. “The Greenland ice cap last winter increased in volume faster than at any time for years.” Jan Lenaerts Assistant Professor, University of Colorado, Boulder: This is not per se completely incorrect, but the author does not tell us the whole story. The author refers to the growing of the ice sheet volume through snowfall throughout winter. The snow accumulated on Greenland in past winter (September-April) has indeed been remarkably high: However, this does not imply that the volume of the ice sheet is increasing, because (1) the ice sheet also loses ice through discharging icebergs; it is the difference between snowfall-driven growth and solid ice discharge that determines if the ice sheet gains or loses volume, and (2) the snow that accumulated during the winter will (at least partly) melt over the summer. That’s why we analyse changes to the ice sheet volume/mass on (at least) annual time scales. Only after the summer we will know how much of the accumulated snow has (not) been melted. uring the past years, the amount of melting has been record-high, and much of snow that accumulated over the winter melted and ran off into the ocean. Concurrently, ice discharge continued, so the Greenland ice sheet LOST considerable volume. We will know in September how much the ice sheet has changed volume this year. Two additional remarks: (a) The word “faster” should not have been used here. We are not talking about the rate of speed, but rather about the total change in volume. Also, it is easier to talk about “mass changes” than “volume changes” since the former is not sensitive to the density of the medium we are talking about (snow has a lower density than ice!). (b) The enhanced snowfall, ironically, is most probably also a signal of the strongly warming Arctic: as the atmosphere warms, it contains more moisture, and generates more precipitation. Also, record-low fall and winter sea ice extent led to large streaks of open water that might have contributed to additional moisture loading of the air. Ruth Mottram, Martin Stendel, Peter Langen, Danish Meteorological Institute Here the author confuses short-term variability (i.e., weather) with a significant change to the Greenland ice sheet. Until a full annual cycle is considered, it is impossible to say if the volume is increasing or not. We can confirm that there has been a record amount of snow and rain over Greenland this winter, most of it fell in October due to extra-tropical hurricane Nicole. However this “extra” winter snowfall is not yet part of the Greenland ice sheet but a snow layer sitting on top of it and the extra gain in snow may be easily wiped out by a warm sunny summer. The summer is by far the most important time of year for the ice sheet—it determines if the ice sheet will grow or shrink so we will not know until September if this winter’s extra snow will have any effect on the overall ice sheet mass budget. Furthermore, we should bear in mind that extra snowfall in Greenland is actually predicted in most climate models, (a warmer atmosphere = more moisture = more snowfall in Greenland) as a consequence of climate change. We should also note that almost all of the additional above average snow fell in the East and South, and north-western Greenland actually has less snow than usual (which you can see in the figure above). 3.Solar activity is expected to only have a minor influence on future temperature. Claims of a “little ice age” coming are based on misrepresentation of scientists’ work and a misunderstanding of the consequences of a solar activity minimum. “Scientists are also expecting a ‘huge reduction’ in solar activity for 33 years between 2020 and 2053 that will cause thermometers to crash.” Georg Feulner Senior Scientist, Potsdam Institute for Climate Impact Research (PIK): Solar activity cannot be predicted. While there are some indicators that future solar activity might indeed be lower, this will have little effect on global temperatures. See, for example,this RealClimate post based on Feulner and Rahmstorf (2010)*. The results have been confirmed by a number of follow-up studies. Feulner and Rahmstorf (2010) On the effect of a new grand minimum of solar activity on the future climate on Earth, Geophysical Research Letters Rasmus Benestad Senior scientist, The Norwegian Meteorological institute: This statement about future solar activity levels between 2020-2050 is completely baseless. Only a few years ago, the scientists were surprised by the recent reduction in the current activity. “He said: ‘We have had five warming cycles since about 900AD, each followed by a dramatic cooling cycle.’” Georg Feulner Senior Scientist, Potsdam Institute for Climate Impact Research (PIK): The global (or even hemispheric) temperature drops during past grand solar minima were actually small. Furthermore, there is increasing evidence that slightly cooler episodes like the “Little Ice Age” were predominantly caused by volcanic eruptions. See, for example,this summaryof Miller et al (2012)*. Miller et al (2012) Abrupt onset of the Little Ice Age triggered by volcanism and sustained by sea-ice/ocean feedbacks, Geophysical Research Letters

https://science.feedback.org/review/another-arctic-ice-panic-world-temperatures-plummet-the-telegraph-christopher-booker/

-2

The Telegraph, by Christopher Booker, on 2017-05-06.

"Another Arctic ice panic over as world temperatures plummet"

The Telegraph published a brief article by Christopher Booker discussing recent Arctic temperatures and sea ice cover in the context of climate change. It is largely based on claims made in a blog post that refers to data from the Danish Meteorological Institute (DMI). But DMI scientists explain that the article “fundamentally misrepresents both our research and the operational data products we provide”. The scientists who have reviewed the article indicate that its claims are misleading or inaccurate. For instance, the article emphasizes that global average temperature has decreased since the end of the 2016 El Niño event, which was expected, but fails to note that this recent decrease by no means reverses the long-term increase in temperature. It also inaccurately claims that global temperature has not warmed over the past 19 years—in direct contradiction with observations. The author claims that last winter in the Arctic was “cold” (-20°C), but fails to recognize that this temperature is much warmer than the norm for the Arctic (by about 5°C), making it the second warmest winter on record. [This article has been used as a reference by another article in the Daily Wire, which expands on false claims made in this Telegraph article.] See all the scientists’ annotations in contextGUEST COMMENTS: Ruth Mottram, Martin Stendel, Peter Langen, Danish Meteorological Institute (with contributions from Mads Ribergaard and Gorm Dybkjær) The articles in The Telegraph and The Daily Wire fundamentally misrepresent both our research and the operational data products we provide freely to the public. Below are the details of where the Telegraph and the Daily Wire stories are misleading or simply wrong based on our data.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Dan Jones Physical Oceanographer, British Antarctic Survey: This article suffers from a common error in reasoning. The author focuses on individual “snapshots” of the state of the climate while ignoring the long-term trends. Those trends occur over many decades and must be observed/considered over those time scales. Andrew King Research fellow, University of Melbourne: This paper peddles common misconceptions about climate change to suggest that global warming is not a problem. It’s extremely misleading and can be easily debunked based on peer-reviewed literature. William Anderegg Associate Professor, University of Utah: This article is highly misleading and factually inaccurate. Jan Lenaerts Assistant Professor, University of Colorado, Boulder: This article mixes short-term weather phenomena and long-term climate trends, and uses logical fallacies and cherry-picked evidence to make a false claim. Alek Petty Postdoctoral associate, NASA Goddard Space Flight Center: Terrible article: Making up facts, cherry picking data, consulting non-scientists, and spouting nonsense. Daniel Swain Climate Scientist, University of California, Los Angeles: For its short length, this article contains an impressive number of falsehoods and willful misinterpretations of data. Essentially all the climate-related claims therein are either demonstrably false or “cherry picked.” Notes:[1] See the rating guidelines used for article evaluations.[2] Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from the article; comments and replies are from the reviewers. 1. There is a long-term warming trend at both the global scale and in the Arctic, which experienced its second-warmest winter on record in 2016/2017. “ever since December temperatures in the Arctic have consistently been lower than minus 20 C” Daniel Swain Climate Scientist, University of California, Los Angeles: It is indeed true that the Arctic is cold in winter—it’s hard to argue with that. But this statement belies the fact that winter 2017 was actually extraordinarily warm by historical standards, and second only to the record-shattering warmth observed just last year (in 2016). The attached plot, created by Zachary Labe and available at http://sites.uci.edu/zlabe/arctic-temperatures, shows that the -20 °C temperatures this winter are nearly 10 °C degrees above the long-term average of -30 °C! Therefore, the fact that temperatures were -20 °C this winter in the Arctic is actually a testament to just how much the Arctic has warmed in recent years. Ruth Mottram, Martin Stendel, Peter Langen, Danish Meteorological Institute (with contributions from Mads Ribergaard and Gorm Dybkjær) This statement is both wrong and misleading. Firstly, most of the Arctic has in fact been consistently warmer than -20 °C this winter. For the period 1 December 2016 to 20 April 2017, the average temperature was above -20 °C everywhere in the central Arctic except north of Greenland and the Canadian Archipelago. Over the Greenland Ice Sheet and in Eastern Siberia (and only there), the temperature was below -25 °C. Secondly, it should not be a surprise that the Arctic is very cold in winter (a period with little to no sunlight). It is much fairer to consider the difference between this winter and the average winter temperatures. Compared to our baseline of 2004-2013 everywhere in the Arctic region was at least 4 °C warmer than the average of 2004-2013 (in itself a warmer baseline period than the 1958-2002 baseline used elsewhere). Around Svalbard, it was about 4.5 °C warmer than average and in Northern Greenland, including Kap Morris Jesup, the world’s northernmost weather station (where a record +3 °C temperature was recorded on one day in February), Ellesmere Island in northeastern Canada, and large parts of eastern Siberia this winter were more than 5 °C warmer than the average as you can see below:Figure: Left, Average temperature over the Arctic for the period December 2016 to April 2017; Right, Deviation of temperature for the period December 2016 to April 2017 from the average 2004-2013.This makes the winter 2016/2017 the second warmest on record in the Arctic (after winter 2015-16), according to the European Copernicus climate service.“record temperatures brought in 2016 by an exceptionally strong El Niño” Andrew King Research fellow, University of Melbourne: Last year the annual global temperature was about 1.1 °C above a late-19th century baseline but only about 0.1°C of this was due to the El Niño—the other 1 °C is due to human influences. So while the record occurred in 2016 due to El Niño, most of the anomaly was due to climate change. “the satellites now show that in recent months global temperatures have plummeted by more that [sic] 0.6 degrees” Daniel Swain Climate Scientist, University of California, Los Angeles: El Niño events do indeed elevate global temperatures temporarily, and this is partly why global temperatures in 2016 were so extreme. But as the attached plot from NASA GISS shows, temperatures so far in 2017 have still been extraordinarily warm in a historical context, and in fact would have been record-breaking if not for the large temperature spike that occurred in 2016. In any case, it is not scientifically meaningful to measure global temperature “trends” over a two year period; the large and statistically significant long-term warming signal overwhelms short-term variations on multi-decadal timescales. William Anderegg Associate Professor, University of Utah: While true (and not necessarily in agreement with the more robust thermometer records for this period, this has no bearing on the long-term climate trend, which is driven by human emissions of greenhouse gases. It is misleading and a logical fallacy to claim this says anything about climate change, which is the long-term change in temperatures. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: While temperatures have declined modestly from the peak of the El Niño event, this is expected behavior, particularly in satellite records where El Niño is amplified. However, temperatures in January through April are quite above average to-date, and while we may not set a record temperature in 2017 compared to 2016, it will very likely be the second warmest year on record (at least on the surface). Through present there is no sign of any sort of pause or slowdown in any of the surface records or one of the two satellite records (the RSS groups latest version 4 record). The only record showing a continued pause is the one produced by the University of Alabama, Huntsville (the UAH record). The differences between these records and their causes is an area of active research, though we have strong reason to suspect that the surface record is quite accurate. “This means the global temperature trend has now shown no further warming for 19 years” Andrew King Research fellow, University of Melbourne: This is both cherry-picking of the data (starting with 1998), and not correct anyway. William Anderegg Associate Professor, University of Utah: This is blatantly false. Examine the trend here: Furthermore, a short time period of a few months in 2017 cannot say anything whatsoever about the long-term change in climate. Andreas Schmittner Associate Professor, Oregon State University: This statement is false. Global temperatures continue their long-term warming trend. 2. Warming in the Arctic is causing changes to the cryosphere: both sea ice and land ice (on Greenland) have been melting faster in recent years. “In April the extent of Arctic sea ice was back to where it was in April 13 years ago” Ed Hawkins Principal Research Fellow, National Centre for Atmospheric Science: In the NSIDC dataset, April 2017 was actually the equal of the lowest Northern Hemisphere extent on record (tied with 2016 on 13.83 M km2). Ruth Mottram, Martin Stendel, Peter Langen, Danish Meteorological Institute This statement is misleading. Arctic sea ice extent in April was significantly lower than the long-term average—but varies substantially from day to day and year to year as processes such as wind and waves and short-term weather variability have a substantial effect on sea ice extent, particularly at this time of year. However, over the long term since 1979, the April sea ice extent has declined by around 3% per decade, at other times of the year the decline is even more marked. This is an example of cherry-picking dates in order to try and state that the sea ice is recovering (it’s not). It also confuses climate variability with trends over short periods. “Furthermore, whereas in 2008 most of the ice was extremely thin, this year most has been at least two metres thick.” Daniel Swain Climate Scientist, University of California, Los Angeles: Arctic sea ice volume has actually exhibited record thinness so far during 2017—beating the previous record years of 2012/2016 by a wide margin. Another nice visualization by Zachary Labe illustrates this quite clearly: “Whereas in 2008 most of the ice was extremely thin, this year most has been at least two metres thick.” Ruth Mottram, Martin Stendel, Peter Langen, Danish Meteorological Institute This is a misleading statement, as “extremely thin” is not defined and what is also not stated is that there were also substantial areas of much thicker ice in 2008. If we look at the total ice volume, which averages these effects out, on 1st May 2017 it was about 6% lower than the ice volume for the same date in 2008 according to the operational ocean and sea ice model. Again, in addition to air and ocean temperature, ice thickness depends on winds and ocean currents and shows large variations from year to year so choosing two years arbitrarily is misleading without considering the long term trend. “The Greenland ice cap last winter increased in volume faster than at any time for years.” Jan Lenaerts Assistant Professor, University of Colorado, Boulder: This is not per se completely incorrect, but the author does not tell us the whole story. The author refers to the growing of the ice sheet volume through snowfall throughout winter. The snow accumulated on Greenland in past winter (September-April) has indeed been remarkably high: However, this does not imply that the volume of the ice sheet is increasing, because (1) the ice sheet also loses ice through discharging icebergs; it is the difference between snowfall-driven growth and solid ice discharge that determines if the ice sheet gains or loses volume, and (2) the snow that accumulated during the winter will (at least partly) melt over the summer. That’s why we analyse changes to the ice sheet volume/mass on (at least) annual time scales. Only after the summer we will know how much of the accumulated snow has (not) been melted. uring the past years, the amount of melting has been record-high, and much of snow that accumulated over the winter melted and ran off into the ocean. Concurrently, ice discharge continued, so the Greenland ice sheet LOST considerable volume. We will know in September how much the ice sheet has changed volume this year. Two additional remarks: (a) The word “faster” should not have been used here. We are not talking about the rate of speed, but rather about the total change in volume. Also, it is easier to talk about “mass changes” than “volume changes” since the former is not sensitive to the density of the medium we are talking about (snow has a lower density than ice!). (b) The enhanced snowfall, ironically, is most probably also a signal of the strongly warming Arctic: as the atmosphere warms, it contains more moisture, and generates more precipitation. Also, record-low fall and winter sea ice extent led to large streaks of open water that might have contributed to additional moisture loading of the air. Ruth Mottram, Martin Stendel, Peter Langen, Danish Meteorological Institute Here the author confuses short-term variability (i.e., weather) with a significant change to the Greenland ice sheet. Until a full annual cycle is considered, it is impossible to say if the volume is increasing or not. We can confirm that there has been a record amount of snow and rain over Greenland this winter, most of it fell in October due to extra-tropical hurricane Nicole. However this “extra” winter snowfall is not yet part of the Greenland ice sheet but a snow layer sitting on top of it and the extra gain in snow may be easily wiped out by a warm sunny summer. The summer is by far the most important time of year for the ice sheet—it determines if the ice sheet will grow or shrink so we will not know until September if this winter’s extra snow will have any effect on the overall ice sheet mass budget. Furthermore, we should bear in mind that extra snowfall in Greenland is actually predicted in most climate models, (a warmer atmosphere = more moisture = more snowfall in Greenland) as a consequence of climate change. We should also note that almost all of the additional above average snow fell in the East and South, and north-western Greenland actually has less snow than usual (which you can see in the figure above).

https://science.feedback.org/review/global-sea-level-rise-accelerating-despite-heartland-institute-reports-claims-otherwise/

Inaccurate

Heartland Institute, Craig Idso, Fred Singer, Robert Carter, 2024-08-14

Best available data show sea-level rise is not accelerating. Local and regional sea levels continue to exhibit typical natural variability—in some places rising and in others falling.

Factually Inaccurate: The observed rate of global sea level rise has increased in comparison to preceding decades or centuries. Fails to Grasp Significance of Observation: Local sea level change can differ from the global average because of land surface elevation trends or ocean circulation variability, but these additional local factors are not indicative of the global sea level trend.

Globally, sea level is rising due to melting glacial ice and warming oceans, and the current rate of sea level rise is faster than past rates.

Best available data show sea-level rise is not accelerating. Local and regional sea levels continue to exhibit typical natural variability—in some places rising and in others falling.

Benjamin Horton Professor, Earth Observatory of Singapore: False. Comparison of long tide gauge records and multi-centennial to millennial scale sea-level reconstructions from the same region indicates that the rate of rise during the instrumental period (since ~1850 CE) was significantly faster than it was during the late Holocene (the 4000–2000 years prior to ~1850 CE). The data demonstrate that an acceleration in the rate of sea-level rise occurred. Kopp et al (2016) Temperature-driven global sea-level variability in the Common Era, Proceedings of the National Academy of Sciences [the article concludes: “A significant global sea level acceleration began in the 19th century and yielded a 20th century rise that is extremely likely (probability P ≥ 0.95) faster than during any of the previous 27 centuries.”] Daniel Swain Climate Scientist, University of California, Los Angeles: This statement is false. A wide range of direct measurements (i.e. tidal gauges) and indirect measurements (i.e., gravity monitoring satellites) show that the rate of sea level rise has increased (i.e., accelerated) in recent years*. Dieng et al (2017) New estimate of the current rate of sea level rise from a sea level budget approach, Geophysical Research Letters [the article concludes: “An important increase of the global mean sea-level rate is found during the second half of the altimetry era (2004–2015) compared to the 1993–2004 time span, mostly due to Greenland mass loss increase and also to slight increase of all other components of the budget.”] Peter deMenocal Professor, Lamont-Doherty Earth Observatory, Columbia University, and Director, Center for Climate and Life: This is untrue. The best available data show that the rate of sea level rise has more than doubled in just the last decade*. Hay et al (2015) Probabilistic reanalysis of twentieth-century sea-level rise, Nature Jeremy Fyke Postdoctoral researcher, Los Alamos National Laboratory: Use of “accelerating” is misleading. Even if the rate wasn’t accelerating (which it is), the fact of a steady rise would still be important. Global average sea level is unambiguously rising. Regions where sea level is falling are regions where local sea level signals are large enough to counteract the global trend—for example, in Baffin Bay and parts of Scandinavia, where continued residual land uplift is continuing, associated with the unweighting of the land from loss of last glacial maximum ice sheets. More details on why local sea level changes can differ from global change can be found in the IPCC report, chapter 13. A recent study finds that sea-level rise recently accelerated significantly, the rate between 1993 and 2012 being three times faster than the rate before 1990*. Dangendorf et al (2017) Reassessment of 20th century global mean sea level rise. Proceedings of the National Academy of Sciences

https://science.feedback.org/review/the-sun-cannot-explain-recent-global-warming-contrary-to-what-heartland-institute-report-claims/

Incorrect

Heartland Institute, Craig Idso, Fred Singer, Robert Carter, 2024-08-14

Solar forcings are not too small to explain twentieth century warming. In fact, their effect could be equal to or greater than the effect of CO₂ in the atmosphere.

Incorrect: The fingerprints of the observed climatic changes do not match those that a change in solar irradiance would generate. Factually Inaccurate: No estimate of 20th century climate forcings (warming or cooling influences) shows the solar forcing to be close to the effect of increased CO2.

The warming influence of CO2 has been much greater than that of the Sun over the past century, and the pattern of observed climate change cannot be explained by solar forcing.

Solar forcings are not too small to explain twentieth century warming. In fact, their effect could be equal to or greater than the effect of CO₂ in the atmosphere.

Timothy Osborn Professor, University of East Anglia, and Director of Research, Climatic Research Unit: There is strong evidence that solar forcing cannot explain much of the observed warming at all. The “fingerprint” of solar forcing does not match the observed changes at all, neither over time nor space. Solar forcing would warm both the stratosphere and the surface of the Earth, whereas CO2 warms the surface (and the troposphere) but cools the stratosphere. Using radiosondes and (more recently) satellites, we have observed a warming surface and troposphere together with a cooling stratosphere. See Santer et al (2013)* for one of many studies providing this evidence. Figure –Zonal-mean atmospheric temperature trends in satellite observations from January 1979 to December 2012 showing warming of the lower atmosphere (troposphere) and cooling of the upper-atmosphere (stratosphere), from Santer et al (2013)* Santer et al (2013) Human and natural influences on the changing thermal structure of the atmosphere, PNAS Britta Voss Postdoctoral Research fellow, U.S. Geological Survey: Solar forcing is much smaller than CO2 forcing. As this figure from the latest IPCC report shows, CO2 radiative forcing (1.68 W/m2) dwarfs solar forcing (0.05 W/m2). Along with other greenhouse gases, CO2 dominates the total radiative forcing when all positive and negative factors are taken into account. Figure – Radiative forcing estimates in 2011 relative to 1750. Values are global average radiative forcing, partitioned according to the emitted compounds or processes that result in a combination of drivers. Source IPCC AR5 Peter deMenocal Professor, Lamont-Doherty Earth Observatory, Columbia University, and Director, Center for Climate and Life: This is untrue. Solar forcing in the visible spectrum is far too small to explain recent warming. Furthermore solar variability would suggest a cooling trend more recently whereas the Earth is clearly warmed.

https://science.feedback.org/review/climate-sensitivity-estimate-given-in-heartland-institutes-report-is-misleading/

Misleading

Heartland Institute, Craig Idso, Fred Singer, Robert Carter, 2024-08-14

Doubling the concentration of atmospheric CO2 from its pre-industrial level, in the absence of other forcings and feedbacks, would likely cause a warming of ~0.3°C to 1.1°C

Misleading: The claim only highlights warming in the absence of any feedbacks, meaning it has limited relevance to the real behavior of the climate system. Even taken on its own, the CO2-only warming range given in this claim is lower than can be determined from physics.

Without additional feedbacks, a doubling of CO2 would cause 1.2 - 1.3°C warming. Feedbacks do exist in the real world, however, and this increases the expected warming to 1.5 - 4.5°C.

Doubling the concentration of atmospheric CO2 from its pre-industrial level, in the absence of other forcings and feedbacks, would likely cause a warming of ~0.3°C to 1.1°C, almost 50 percent of which must already have occurred.

Jeremy Fyke Postdoctoral researcher, Los Alamos National Laboratory: Neglecting feedbacks in this statement is seriously misleading to uninformed readers. Feedbacks have been clearly identified as major amplifiers of the initial CO2-forced change. These feedbacks are explicitly resolved in climate models. Mark Zelinka Research Scientist, Lawrence Livermore National Laboratory: The first part of the statement is true, though the numerical values are off. Without other feedbacks to amplify the planetary heating due to CO2, the expected global warming from doubling CO2 is about 1.2 to 1.3°C. See p.96 of Roe (2008)1for a nice explanation of this. Of course, we know that there are important feedbacks in the climate system, and several of them are strong and positive, causing additional warming on top of this basic response. Narrowing down the plausible ranges of the strength of these feedbacks is an abiding goal of climate science (e.g. Stevens et al, 2016)2. Evidence has consistently pointed towards a global warming of 3°C for a doubling of CO2, albeit with uncertainty. See Armour (2017)3 for a recent study that adds to this body of evidence. So the quoted no-feedback warming of ~1 degree is completely irrelevant to Earth. It is useful only in an academic sense as a hypothetical baseline climate response that is subsequently modified by feedbacks. The second part of the statement—that half of the warming must have already occurred (presumably because CO2 levels have increased by 50% since preindustrial)—is not true. We do not expect the ultimate global warming due to doubling of CO2 to occur at the exact moment that CO2 is doubled any more than we expect water to instantaneously boil when a pot is placed on a hot stove. There is a lag between the heating due to CO2 and the surface temperature response owing to the heat capacity of the climate system, especially the ability of the ocean to take up heat. 1- Roe (2008) Feedbacks, Timescales, and Seeing Red, Annual Reviews 2- Stevens et al (2016) Prospects for narrowing bounds on Earth’s equilibrium climate sensitivity, Earth’s Future 3- Armour (2017) Energy budget constraints on climate sensitivity in light of inconstant climate feedbacks, Nature Climate Change James Renwick Professor, Victoria University of Wellington: The CO2-only warming is at the top end of this range. The water vapor feedback roughly doubles the warming, and other feedbacks (such as ice-albedo) add another degree or so. The most likely value for real-world climate sensitivity is around 3°C, with a range from about 1.5°C to 4.5°C, as has been well known for 40 years.

https://science.feedback.org/review/cnn-interview-william-happer-incorrectly-claims-temperatures-dont-match-climate-model-projections/

Incorrect

CNN, William Happer, 2017-04-22

The temperature is not rising nearly as fast as the alarmist computer models predicted. You know, it’s much, much less, factors of 2 or 3 less.

Unsupported: Observed warming since the 1970s is consistent with climate model projections, the factor of 2 or 3 mentioned by Happer is not supported by available observations. Fails to grasp significance of observation: Comparing short-term natural variations in global temperature with average long-term trends from model simulations is not an apples-to-apples comparison.

Global surface temperatures are increasing consistent with the long-term trend projected by climate models, which are useful tools for understanding the consequences of continued greenhouse gas emissions.

The temperature is not rising nearly as fast as the alarmist computer models predicted. You know, it’s much, much less, factors of 2 or 3 less. So the whole basis for the alarmism is not true, it’s based on flawed computer modeling.

Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: Dr. Happer’s assertion that models show 2x to 3x greater warming than observations is incorrect. At the surface (where we all live) models predict a rate of warming of 0.2°C per decade since 1970, while NASA observes warming of around 0.18°C during the same period. During this period models have been running about 10% too hot, hardly 200% to 300%. Similarly, the observations from all the different groups that measure global surface temperatures are well within the envelope of model projections: Over a longer timeframe, since we first started observing global temperatures in the late 1800s, models have also matched observations fairly well: Cowtan et al (2015) Robust comparison of climate models with observations using blended land air and ocean sea surface temperatures, Geophysical Research Letters Mat Collins Professor, University of Exeter: Looking over the last 50 years, for example, the models and the observations are consistent in terms of the rates of global temperature warming that we expect from human activities. Over shorter decadal periods, there are natural fluctuations in climate in the real world that are much harder to predict. It is true that models do not provide perfect simulations of the real world climate. However, we have considerable confidence in long-term trends at the global scale. For shorter time scales and for regional scales, we still have some work to do. Pierre Friedlingstein Professor, University of Exeter: Climate models are doing an excellent job reproducing the warming of the 20th century. They simulate a warming consistent with the observations and they can actually attribute the warming trend over the century to the observed increase in CO2, other greenhouse gases, and aerosols. What they have a harder time simulating in phase with observations is the natural variability—in particular the relative pause in warming that occurred in the last decade (1998-2013 or so). But again, this has very little to do with CO2 and climate change; this is mainly about decadal variability in the global ocean circulation.

https://science.feedback.org/review/cnn-interview-william-happer-misleads-impact-rising-carbon-dioxide-plant-life/

Misleading

CNN, William Happer, 2017-04-22

there's this myth that's developed around carbon dioxide that it's a pollutant […] Carbon dioxide is a perfectly natural gas, it’s just like water vapor, it’s something that plants love.

Misrepresents a complex reality: While ecosystems on land have taken up CO2 emitted by humans, this is not simply a beneficial interaction. Plants require more than just CO2, and the climatic effects of greenhouse gas emissions can have negative impacts on ecosystems, as well.

Land ecosystems absorb a portion of human-caused CO2 emissions, which has indeed increased plant growth. But CO2 also negatively impacts on plants and ecosystems as well as human societies by causing the climate to change significantly.

there's this myth that's developed around carbon dioxide that it's a pollutant […] Carbon dioxide is a perfectly natural gas, it’s just like water vapor, it’s something that plants love. They grow better with more carbon dioxide, and you can see the greening of the Earth already from the additional carbon dioxide in the atmosphere.

Sara Vicca Postdoctoral research fellow, University of Antwerp: That claim is correct, and it is generally assumed the elevated CO2 concentrations have contributed considerably to the land carbon sink (ca. 30% of our CO2 emissions have been absorbed by land ecosystems). The claim may still be misleading, though. Plants don’t only need CO2 and water, but also nutrients like nitrogen and phosphorus. If the latter are not sufficiently available, plants may not respond to elevated CO2 at all. Moreover, climatic changes (and particularly extreme events) are an important threat to ecosystems and to the land carbon sink. It is expected that nutrient limitations and extreme events will reduce the land carbon sink and may eventually turn the land into a source of CO2. I didn’t mention soil (for simplicity), but that’s an important part of the land carbon sink, too. Zhu et al (2016) Greening of the Earth and its drivers, Nature Climate Change Terrer et al (2016) Mycorrhizal association as a primary control of the CO2 fertilization effect, Science De Graaff et al (2006) Interactions between plant growth and soil nutrient cycling under elevated CO2: a meta-analysis, Global Change Biology Zaehle et al (2015) Nitrogen Availability Reduces CMIP5 Projections of Twenty-First-Century Land Carbon Uptake, Journal of Climate Zhang et al (2014) Nitrogen and phosphorous limitations significantly reduce future allowable CO2 emissions, Geophysical Research Letters Reichstein et al (2013) Climate extremes and the carbon cycle, Nature Alexis Berg Research Associate, Harvard University: Yes, we are seeing an increase in vegetation around the world, with satellites showing up to 50% of the land surface greening over the last 30 years, most of it being indeed attributed to increased atmospheric CO2*. This is not a surprise. This vegetation increase is consistent with the fact that we know that about a quarter of our CO2 emissions is being taken up by the land biosphere (another quarter going into the oceans, and the remainder staying in the atmosphere). This greening is taken into account in climate models. The real question is how long this greening is going to go on (there are already indications that it is slowing down), as we expect that as climate warms further, adverse impacts on ecosystems may start to offset the positive impact of increased atmospheric CO2—particularly in places where regional climate is moving away from the “comfort zone” of current ecosystems. Zhu et al (2016) Greening of the Earth and its drivers, Nature Climate Change Jean-François Exbrayat Post-doctoral Research Fellow, The University of Edinburgh: Carbon dioxide is a gas that is naturally present in the atmosphere. Plants grow by taking up CO2 from the atmosphere through the process of photosynthesis. Terrestrial ecosystems have taken up about 20-30% of fossil-fuel emissions since the 1960s[1]. Through this so-called “CO2-fertilization”, plants help reduce the growth of atmospheric CO2 responsible for climate change, and this might be what William Happer refers to when talking about greening. A global “greening”, (i.e., longer growing seasons) of the Earth has also been detected in satellite observations of leaf area index from the 1980s to the present day, and modelling experiments have attributed 70% of this greening to CO2 fertilization[2]. However, plants grow better with more CO2 only if they also have access to nutrients like nitrogen and phosphorus to fix the photosynthesised carbon. For example, results from Free-Air CO2 Enrichment (FACE) experiments[3] have shown that the initial enhancement of plant productivity under CO2-fertilization was declining through time. This enhancement could, however, be restored and maintained through an additional nitrogen treatment. Results from another FACE experiment in Australia[4] have recently shown that, under current phosphorus limitations, no additional growth was recorded under increased CO2. These results from FACE experiments raise uncertainty on the sustainability of the CO2-fertilization effect in mostly nitrogen-limited temperate and boreal forests and mostly phosphorus-limited tropical ecosystems. Accordingly, adding nitrogen and phosphorus limitations on plant growth in Earth system models reduces the projected capacity of the land surface to continue offsetting fossil-fuel emissions during the 21st century[5]. [1] Le Quéré et al (2016) Global Carbon Budget 2016, Earth System Science Data [2] Zhu et al (2016) Greening of the Earth and its drivers, Nature Climate Change [3] Norby et al (2010) CO2 enhancement of forest productivity constrained by limited nitrogen availability, PNAS [4] Ellsworth et al (2017) Elevated CO2 does not increase eucalypt forest productivity on a low-phosphorus soil, Nature Climate Change [5] Wieder et al (2015) Future productivity and carbon storage limited by terrestrial nutrient availability, Nature Geoscience Pierre Friedlingstein Professor, University of Exeter: This is the usual misleading argument that if CO2 is good for plants, it cannot be bad for the climate. Happer’s statement is correct—CO2 is needed for plant growth (along with water, nutrients, and energy from the sun)—but it does not change the fact that CO2 is a greenhouse gas. It increases the radiative forcing of the planet and leads to warming, as observed over the last century. What he says is like saying, “Sun cannot cause skin cancer. The sun is natural, it’s something plants love, they grow better with more sunshine!”

https://science.feedback.org/review/bloomberg-accurately-describes-rapidly-changing-arctic-eric-roston-blacki-migliozzi/

2

Bloomberg, by Blacki Migliozzi, Eric Roston, on 2017-04-19.

"How a Melting Arctic Changes Everything"

This Bloomberg article gives a brief overview of ways in which the Arctic is changing as it warms, including the loss of sea ice and the thawing of permafrost. Scientists who reviewed the article found that it accurately described these changes, and illustrated them using appropriate datasets. However, several confident statements could be qualified with additional context to provide a clearer picture.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Michel Tsamados Lecturer (Assistant Professor), University College London: The quality of the figures along with the accuracy of the text make this a very good summary of the current state of the cryosphere in the Arctic region. Jennifer Francis Senior Scientist, Woods Hole Research Center: Changes in the Arctic are breath-taking and extremely worrisome. This article does an excellent job of summarizing some of the most conspicuous ones in language understandable by public audiences.Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from the article; comments and replies are from the reviewers. Declining Arctic sea ice cover and thawing permafrost are both complex feedbacks that amplify global warming: The loss of reflective sea ice means more sunlight absorbed by the dark Arctic Ocean, while thawing permafrost can release greenhouse gases to the atmosphere. “Scientists refer to these dramatic physical changes as ‘Arctic amplification,’ or positive feedback loops. It’s a little bit like compound interest. A small change snowballs, and Arctic conditions become much less Arctic, much more quickly.” Michel Tsamados Lecturer (Assistant Professor), University College London: Along with positive feedbacks (albedo, ice weakening, etc.) come negative feedbacks (faster growth of thinner ice, compaction, etc.) which make the fragile thin sea ice cover surprisingly resilient. So while the extent and area of sea ice might be at a lowest point, it remains to be seen if this will materialize in a similar level for the volume of ice. Having said that, the temperature and ice coverage anomalies of the 2016/2017 Fall/Winter have been remarkable and have further triggered scientists’ curiosity. “Sea ice has diminished much faster than scientists and climate models anticipated.” François Massonnet Postdoctoral Research Fellow, Université catholique de Louvain: Caution must be exercised when making such statements, and in particular how they should be interpreted. It is a fact that the observed linear trend in summer Arctic sea ice extent is more negative than the average of all the models having participated to the third and fifth phase of the Coupled Model Inter-comparison Project (CMIP3/5). It is also a fact that individual model realizations, and in fact a non-negligible number of them, have more negative trends than observed: this is the case for 17 out of 66 (~26%) in the CMIP5 ensemble (figure below). From there, we can’t robustly exclude that the observed and simulated trends are statistically different from each other. Figure – (a) Time series of sea ice extent for the Arctic in September, as modelled in CMIP5 (coloredlines) and observations-based (NASA and NSIDC). Each model is represented with a single simulation. (c) CMIP5 sea ice extent trend distributions over the period 1979–2010 for the Arctic in September. Altogether 66 realizations are shown from 26 different models (historical simulations extended after 2005 with RCP4.5 projections). They are compared against the observations-based estimates of the trends (green and blue vertical lines).Source: adapted from IPCC AR5 WG1, Chapter 9, Fig. 9.24 Let’s make a thought experiment and rewind nature back to 1979. Then let’s clap our hands, creating an infinitesimal disturbance in the atmosphere. Due to the chaotic nature of the atmosphere, this disturbance will cause nature to follow a different path from the one we have known. The trend in sea ice extent will also be different, and potentially very different from the one we have observed, according to model simulations*. What to understand from this? While these random effects of internal variability can be averaged out by running multiple times the same models, or different models, the same can’t be done for the (one) observation we have. We have to acknowledge that the difference between the (one) observed trend and the average simulated trend can, in part, be explained by internal variability that, by definition, historical climate model simulations are not supposed to anticipate. Hence, the statement that sea ice extent has shrunk faster than anticipated has to be taken with care. Notz (2015) How well must climate models agree with observations?, Philosophical Transactions of the Royal Society A Jennifer Francis Senior Scientist, Woods Hole Research Center: The main take-home message is that sea ice is disappearing very fast and we know why. It’s a clear response to the fact that carbon dioxide concentrations in the atmosphere are now higher than have been in at least 2 million years, mainly due to burning fossil fuels. The sea ice is a critical component of the Earth’s climate system, and losing over half of it in less than a human generation is already having repercussions well beyond the Arctic. “Arctic land stores about twice as much carbon as the atmosphere. While growing seasons—which are now either longer or newly possible, depending on the exact location—suck in carbon dioxide during the spring and summer, scientists believe the thawing lands are now emitting more carbon than they take in.” Jeff Chanton Professor, Florida State University: Yes, and in addition they will increase the methane that they emit, which may offset carbon that might be taken up if that is the case. “Perhaps the most visually dramatic change in the landscape has been occurring in Russia. Warming temperatures have accelerated the rate of natural underground methane leaks. The gas builds up in the soil, forming mounds called ‘pingoes.’ When the pressure becomes too great, the ground explodes, leaving 30 to 40-meter-wide craters.” [picture] Carolyn Ruppel Research Geophysicist, United States Geological Survey: In the review paper* that we published early this year, we said only this: “In recent years the discovery of deep, rapidly developed Yamal Peninsula craters that emit CH4[methane] has been attributed by some to thawing gas hydrates, although recent analyses of high-resolution satellite imagery implies pingo collapse as a more likely cause”. Normal pingoes are widespread even on the Alaskan North Slope, and they are generally believed to be ice-cored. The “alternative” pingoes that have been in the news recently and that the Bloomberg article alludes to would not have ice at their cores, according to that interpretation. Many workers have measured high methane concentrations in and near these craters on the Yamal Peninsula, but I have no way of knowing whether (a) methane is genetically related to the craters’ evolution or (b) the craters evolve first by still-not-understood processes and the crater then has access to methane that is already in the surrounding/underlying soils or produced by microbes acting on buried organic carbon (so the methane leaking into the crater is what causes high concentrations within). I also can’t say whether the phenomenon of crater formation is widespread enough and whether these craters are releasing enough methane to the atmosphere for these features to have an appreciable impact on high-latitude methane releases. Ruppel and Kessler (2017) The interaction of climate change and methane hydrates, Reviews of Geophysics

https://science.feedback.org/review/climate-context-for-a-wet-winter-in-drought-stricken-california-in-the-la-times-rong-gong-lin-ii-paige-st-john-los-angeles-times/

0.8

Los Angeles Times, by Paige St. John, Rong-Gong Lin II, on 2017-04-12.

"From extreme drought to record rain: Why California's drought-to-deluge cycle is getting worse"

This article in The Los Angeles Times discusses the recent exceptionally wet winter in California, which followed several years of extreme drought conditions. These events are put into the context of trends in recent decades and the future projections of continued human-caused climate change. Warming temperatures are expected to increase the magnitude of both dry years (since evaporation increases with temperature) and wet years (since a warmer atmosphere has a greater “water-holding capacity”), which can sound counterintuitive at first. Scientists who reviewed the article found it to be a generally accurate description of the state of scientific knowledge on these complex topics.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Daniel Swain Climate Scientist, University of California, Los Angeles: This timely article accurately characterizes the broader climate context of California’s rapid transition from drought to flood. Andreas Prein Project Scientist, National Center for Atmospheric Research: The article is accurate and highlights the challenges that California’s water resource managers are facing due to climate change. There are some issues with differentiating natural climate variability and forced climate change but the main points are correct. Baird Langenbrunner Associate Editor, Nature Climate Change: This article is balanced and accessibly written, and its description of the recent history of California’s weather is accurate and clear. The authors do not substantiate all of their claims, nor do they explain mechanisms underlying the changes they discuss, but for its intended purpose—an article contextualizing recent California extremes within the historical record and how they might be changing—it seems to fit the bill. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from the article; comments and replies are from the reviewers. Extremes of drought and precipitation in California have increased in frequency, which is also a pattern climate models predict for the future. Natural year-to-year variability of California precipitation is high though, so it is uncertain whether the influence of climate change is already detectable. “The extreme cycles of dry and wet weather appear to have been intensifying over the last three decades.” Daniel Swain Climate Scientist, University of California, Los Angeles: There is indeed observational evidence that California precipitation extremes—and the atmospheric phenomena that cause them—have occurred more frequently in recent years*, although that signal has only recently emerged from the “noise” of natural climate variability. There is also an expectation that such swings between extreme dry and extreme wet will continue to become more pronounced as the climate warms*. Swain et al (2016) Trends in atmospheric patterns conducive to seasonal precipitation and temperature extremes in California, Science Advances Diffenbaugh et al (2015) Anthropogenic warming has increased drought risk in California, PNAS Wang et al (2015) The North American winter ‘dipole’ and extremes activity: a CMIP5 assessment, Atmospheric Science Letters Yoon et al (2015) Increasing water cycle extremes in California and in relation to ENSO cycle under global warming, Nature Communications Berg and Hall (2015) Increased Interannual Precipitation Extremes over California under Climate Change, Journal of Climate Gao et al (2017) Twenty-First-Century Changes in U.S. Regional Heavy Precipitation Frequency Based on Resolved Atmospheric Patterns, Journal of Climate A. Park Williams, Assistant Research Professor, Lamont-Doherty Earth Observatory: Yes, variability in California precipitation appears to have been higher in the past 3-4 decades than the previous decades, but it is not (and cannot be) clear that that the variability in precipitation is actually currently in the act of increasing. I say that it cannot be clear because it takes decades of data (say 2-3) to characterize the current “variability” of the climate. Based on my calculations, variability in annual precipitation totals increased considerably during the second half of the 1900s and then has remained at this relatively high level for the past couple decades, but has not clearly continued to increase. This latest swing from record dry to very wet in the last year is consistent with high variability, but it’s a single event and not necessarily indicative of a trend. There are some logical links, however, that support the inference that wild swings like the current one should be expected to become more likely. First, droughts are becoming increasingly impacted by warming temperatures. Even if precipitation behavior didn’t change at all, years with low precipitation would correspond to less and less water availability for humans and ecosystems. Second, current climate models project variability of California precipitation to increase in the future, with an increase in the frequency of years with very high precipitation totals becoming detectable sometime in the first half of this century, and an increase in the frequency of years with very low precipitation totals becoming detectable in the second half of this century*. It should always be remembered, however, that models have a tough time with California precipitation. California is right on the boundary between projections of drying to the south and wetting to the north. I personally believe the basic expectation that California precipitation should become more variable, but beyond that I don’t yet put much stock in what models have to say about the future of precipitation in California. So, variability has increased overall in the last century, and this is consistent with what models project to occur as a result of greenhouse-gas driven climate change. The increase in variability hasn’t been a monotonic trend, however, and it is not obvious from the data that the trend is continuing now as rapidly as it was in previous decades. This suggests that other low-frequency processes are also at play that influence decade-to-decade changes in the variability and magnitude of annual precipitation totals, making it particularly difficult to determine the degree to which this current event can be attributed to climate change. Nonetheless, California would be wise to prepare for more events like these. Berg and Hall (2015) Increased Interannual Precipitation Extremes over California under Climate Change, Journal of Climate “Warm weather worsened the most recent five-year drought, which included the driest four-year period on record in terms of statewide precipitation. California’s first-, second- and third-hottest years on record, in terms of statewide average temperatures, were 2014, 2015 and 2016.” Daniel Swain Climate Scientist, University of California, Los Angeles: This claim is supported by a wide range of scientific research*. Record warmth during the recent drought has also been directly implicated in some of the most iconic drought impacts, such as extreme lack of Sierra Nevada snowpack* and a large increase in wildfire intensity*. Diffenbaugh et al (2015) Anthropogenic warming has increased drought risk in California, PNAS Williams et al (2015) Contribution of anthropogenic warming to California drought during 2012–2014, Geophysical Research Letters Belmecheri et al (2016) Multi-century evaluation of Sierra Nevada snowpack, Nature Climate Change Yoon et al (2015) Increasing water cycle extremes in California and in relation to ENSO cycle under global warming, Nature Communications Baird Langenbrunner Associate Editor, Nature Climate Change: There is evidence that warmer temperatures across the globe affect large-scale atmospheric dynamics, which in turn feed into regional weather patterns. The relevant example here is the argument that a warming Arctic will reduce large-scale temperature gradients in the atmosphere, which will in turn affect (and be affected by) the complex path that storms follow across the Pacific Ocean as they approach the North American west coast. While the extent to which this has already happened is debatable*, there is agreement that it will be a robust signal if Arctic warming continues unabated*. Cohen et al (2014) Recent Arctic amplification and extreme mid-latitude weather, Nature Geoscience Overland et al (2015) Nonlinear response of mid-latitude weather to the changing Arctic, Nature Climate Change Screen (2017) Climate science: Far-flung effects of Arctic warming, Nature Geoscience “And this winter’s near disaster at the overflowing Lake Oroville was in part caused by warm storms too.” Daniel Swain Climate Scientist, University of California, Los Angeles: The skewed rain-snow ratio this season certainly contributed to some of the precipitation-related impacts this winter. While winter 2016-2017 was not exceptionally warm in the Sierra Nevada, especially relative to recent record-warm years, it was still warmer than average. In middle elevation zones of the Sierra Nevada, precipitation fell as rain rather than snow more often that would have historically been the case—leading to a snowpack that significantly lagged overall liquid precipitation (although both were well above average). (See this article in Eos.) “Not everyone is convinced that the evidence is in that climate change is responsible for extreme swings between drought and deluge.” Daniel Swain Climate Scientist, University of California, Los Angeles: There is a considerable and growing body of scientific evidence (see above references) demonstrating that California will likely experience increasingly large swings between extreme wet and extreme dry conditions. The evidence that climate change has already caused such an increase is somewhat less strong—mainly because there are relatively few extreme events in the historical record from which to draw such conclusions. Therefore, this statement is imprecise, and may be misleading if it is intended to convey that scientists substantially disagree regarding the likely future increase in California precipitation extremes. Whether such an increase is yet detectable in the historical record is indeed uncertain; there is much greater certainty regarding the likely direction of future change. “‘The dry periods are drier and the wet periods are wetter,’ said Jeffrey Mount, a water expert and senior fellow at the Public Policy Institute of California.” Andreas Prein Project Scientist, National Center for Atmospheric Research: This is seen in assessments of atmospheric reanalyses, which show a decreasing frequency of rain-producing weather systems over California but higher rain rates over the last 35 years*. Prein et al (2016) Running dry: The U.S. Southwest’s drift into a drier climate state, Geophysical Research Letters

https://science.feedback.org/review/sea-level-rise-already-practical-concern-miami-bbc-story-accurately-explores-amanda-ruggeri-bbc/

1.7

BBC, by Amanda Ruggeri, on 2017-04-04.

“Miami’s fight against rising seas”

This BBC feature article discusses the challenges that sea level rise poses for Miami, Florida in detail. Global sea level rise projected to occur in the coming decades due to human-induced climate change threatens coastal infrastructure in low-lying areas like southeast Florida. Scientists who reviewed this story found it to be insightful and generally accurate. They note that care should be taken not to misinterpret short-term variations in local sea level rise trends, such as the higher rate of sea level rise in Florida over the past decade, which is not expected to continue over the long term.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Tal Ezer Professor, Old Dominion University: The information in this story is generally correct—the frequency and severity of flooding is accelerating due to sea level rise, and the quoted scientists from NOAA and FAU are credible experts in this field. Andrea Dutton Visiting Associate Professor, University of Wisconsin: The article provides many internal references to peer-reviewed research, which supports many of the scientific claims made here, including the observation that in recent years the rate of sea-level rise in southeast Florida has accelerated. Additional insight on the implications of the research is made, including the observation that vulnerable infrastructure situated at lower elevations will be critical to sustain even those structures that are at slightly higher elevation; hence it is not the elevation of your home that is as critical as the elevation of the infrastructure that supports it. However, having argued throughout the piece that sea levels are rising quickly in this region and that a swift, coordinated response is required, I found the ending overly optimistic. It is not helpful to sustain the unrealistic belief that human innovation will enable us to just engineer our way out of this situation in south Florida indefinitely.Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from the article; comments and replies are from the reviewers. 1.The 21st Century could see a meter or more of sea level rise as the oceans continue to warm and glacial ice is lost, presenting a threat to low-lying coastal areas like southeast Florida. “Not only are sea levels rising, but the pace seems to be accelerating” Benjamin Horton Professor, Earth Observatory of Singapore: The largest change in rate of sea-level rise is between the background pre-industrial period and the 20th century. Sea-level rose 1.27 ± 0.09m in northeastern Florida (USA) during the past ~2600 years, a rate of about 0.49 mm/yr. The tide-gauge data from nearby Fernandina Beach, measures 1.91 ± 0.26mm/yr of RSL rise since 1900CE. “The most frequently-used range of estimates puts the likely range between 15-25cm (6-10in) above 1992 levels by 2030, and 79-155cm (31-61in) by 2100.” Andrea Dutton Visiting Associate Professor, University of Wisconsin: It is true that these are commonly used projections in this region. This statement refers to the Unified Sea Level Rise Projection that was produced by the Southeast Florida Regional Compact on Climate Change. “enough credible projections have been done to put together a range of scenarios that researchers are confident about” Andrea Dutton Visiting Associate Professor, University of Wisconsin: Many projections have been done, but they may very well underestimate the true expected range of scenarios. “But as more data comes in, even the worst-case estimates may turn out to be too low: for example, researchers recently discovered that ice is melting more rapidly than expected from both Antarctica and Greenland, plus gained a better understanding of how melting ice sheets actually affect sea-level rise. ‘The unlikely scenarios are now, all of a sudden, becoming more probable than they once were thought to be,’ says Sweet.” Andrea Dutton Visiting Associate Professor, University of Wisconsin: This is true, based on the research cited here. The dynamics of rapid ice sheet retreat remain uncertain which introduces uncertainty into the projections. “The most dramatic impacts may not be felt for 50 or 100 years.” Andrea Dutton Visiting Associate Professor, University of Wisconsin: While the most dramatic effects may not be felt until 50 to 100 years from now, that does not mean that dramatic impacts will not occur before then. “many of south Florida’s drainage systems and seawalls are no longer enough” Andrea Dutton Visiting Associate Professor, University of Wisconsin: This statement is true based on several different analyses. For example, in a study* that quantified the reduction of flood control capabilities of coastal water control gravity structures owing to increased sea level rise, they found that “sea level change could negatively impact nearly half the coastal flow control structures in the coming decades, unless adaptive measures are implemented to mitigate such impacts.” Obeysekera et al (2011) Climate change and its implications for water resources management in south Florida, Stochastic Environmental Research and Risk Assessment 2.Over shorter timescales, regional sea level trends can differ significantly from the long-term trend due to additional factors like ocean circulation. “Sea level rise is global. But due to a variety of factors – including, for this part of the Atlantic coast, a likely weakening of the Gulf Stream, itself potentially a result of the melting of Greenland’s ice caps – south Floridians are feeling the effects more than many others. While there has been a mean rise of a little more than 3mm per year worldwide since the 1990s, in the last decade, the NOAA Virginia Key tide gauge just south of Miami Beach has measured a 9mm rise annually.” Tal Ezer,Professor, Old Dominion University:: The main reason for higher than normal local sea level rise in places like Miami, FL, and Norfolk, VA, is that in addition to well documented global sea level rise, there are places with local land subsidence and also influence from ocean currents like the Gulf Stream. The influence of the Gulf Stream on the coast is my expertise*, but the issue is quite complicated. It is true that slowdown of the Gulf Stream will cause sea level to rise along the US East Coast and there are some signs that the Gulf Stream started to slow down due to long-term climate change, weakening the entire Atlantic Ocean circulation. However, short term fluctuations in the Gulf Stream (which may or may not relate to climate change) can also create periods of higher than normal water levels and unpredictable tidal flooding, and this is an area of active recent research. Ezer et al (2013) Gulf Stream’s induced sea level rise and variability along the U.S. mid-Atlantic coast, Journal of Geophysical Research-Oceans Stefan Rahmstorf Professor, Potsdam University: This statement touches upon several issues that are indeed discussed in the scientific literature and it is essentially correct. Let’s try and disentangle things. It is correct that Virginia Key as well as other locations on the US Atlantic coast have experienced a surge of rapid sea-level rise during the past ten years or so. However, this is a very short period in terms of sea-level variations. The longer-term rise in this region (when corrected for local land subsidence) is actually in line with the global average sea-level rise, both for the past hundred years (~1.8mm per year) or measured since the early 1990s (~3 mm per year). The recent rapid rise is thus likely a short-term natural variation (a possibility mentioned later in the article) and may well be followed by a period of very little rise. In the longer run I would expect that sea-level near Miami would continue to increase roughly in line with the global mean sea-level rise, as is indeed discussed later in the article where the future projections with their uncertainties are covered well. It is correct that local sea-level rise can differ from global sea-level rise due to “a variety of factors”, including a weakening of the Gulf Stream. For the relevant period of rapid rise, the last ten years or so, such a weakening has been documented, e.g. in the direct measurements in the RAPID section at 26 °N. So the rapid sea-level rise and the weakening of the larger Gulf Stream System coincide, and have indeed been linked.* Like with sea level, over the short time scale of the past decade this is likely to be dominated by natural variability, although there are also indications of a longer-term, probably human-caused, downward trend. Greenland melting has not caused this, but likely contributed to it. To what extent the Gulf Stream weakening explains the recent rapid sea-level rise in Miami, and to what extent other factors—like changes in the predominant winds—are responsible remains an open research question. Ezer et al (2013) Gulf Stream’s induced sea level rise and variability along the U.S. mid-Atlantic coast, Journal of Geophysical Research-Oceans Benjamin Horton Professor, Earth Observatory of Singapore: True: Sea-level rise in Florida is the result of a variety of factors. But the influence of a weakening Gulf Stream will be felt more in the northeast of the US than Florida. Furthermore, land level subsidence due to glacial isostatic adjustment is less in Florida than the mid and northeast Atlantic. With respect to melting from Greenland, yes, Florida will feel a greater impact than regions to the North. But the rate of rise will be less than the global average. Focusing on the last decade and one tide gauge could be considered cherry-picking the data. Long-term (>60yrs) tide gauges should be used. Virginia Key has only been operational since 1994. Key West Tide gauge has been operational since 1901 and records a rate of sea-level rise of 2.37 mm/yr. Andrea Dutton Visiting Associate Professor, University of Wisconsin: The hypothesis that (a) the Gulf stream has weakened over this time interval and (b) that it is the primary driver of sea level rise acceleration seen farther north along the U.S. Atlantic coast is still debated (see for example, Kopp 2013)*. Kopp (2013) Does the mid-Atlantic United States sea level acceleration hot spot reflect ocean dynamic variability?, Geophysical Research Letters “Can we definitely say it’s the ocean warming?” says Sweet, who has authored several sea-level rise studies. “No. But is it indicative of what we’d expect to see? Yes.” Andrea Dutton Visiting Associate Professor, University of Wisconsin: It is not yet clear what is causing the recent uptick in the rate of sea level rise in this region over the past several years, which is not similarly recorded at tide gauges north of Cape Hatteras according to the NOAA tide gauge data. If, however, this quote refers to the long-term trend of sea-level rise in this region, then it is correct and consistent with the analysis of the latest IPCC report* (Church and Clark, (2013) Chapter 13, IPCC AR5). Church et al (2013) Chapter 13: Sea Level Change, In: Climate Change 2013: The Physical Science Basis, IPCC

https://science.feedback.org/review/one-of-the-most-troubling-ideas-about-climate-change-just-found-new-evidence-in-its-favor-chris-mooney-washington-post/

1.25

The Washington Post, by Chris Mooney, on 2017-03-27.

"One the most troubling ideas about climate change just found new evidence in its favor"

This article in The Washington Post discusses a new study related to the hypothesis that global warming is influencing extreme weather events in the midlatitudes by changing the behavior of the jet stream. While many previous studies have explored statistical correlations, the new study provides a specific process that can plausibly explain how enhanced Arctic warming trends may trigger remote weather impacts. Specifically, it focuses on slow-moving meanders in the jet stream in the spring and summer than can cause extended periods of hot or wet weather. The scientists who reviewed the article confirm that it is accurate and insightful, and acknowledges the areas where legitimate scientific uncertainty remains.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. James Screen Associate Professor, University of Exeter: The author does a pretty good job of summarising the state of the science on this topic and the main advance made by the new Mann et al study. It conveys some of the uncertainty and difficulties in attributing changes in the jet strea—and in “stuck” weather patterns—to man-made climate change. It is worth noting that the Mann et al study only claims a climate change effect on the jet stream in summer. However, much of the research referred to in the article is about winter and invokes different physical processes to explain the possible climate change effects on the jet stream. My ranking of “high” rather than “very high” reflects the failure of this piece to fully capture the seasonal nuances of possible connections between climate change and the jet stream. Jennifer Francis Senior Scientist, Woods Hole Research Center: The new study addresses a very complicated topic in dynamic meteorology and climate science, and this article does an excellent job of explaining the main idea and its implications. It is balanced, accurate, and well written. Jim Kossin Research Scientist, NOAA's Center for Weather and Climate: Excellent article that should be very informative for a broad audience. There are a few somewhat misleading statements that place too much emphasis on the ongoing debate about how winter storms may be linked to Arctic warming, which are not directly addressed in the new paper by Mann et al. The new results might be inferred indirectly to favor one side of the debate, but this may prove to be incorrect later. Daniel Swain Climate Scientist, University of California, Los Angeles: Overall, this piece accurately describes the findings of a new research paper by Mann et al on linkages between rapid Arctic warming and extreme weather at Earth’s more temperate latitudes. While there are a couple of statements that are overly confident given available evidence in the peer-reviewed literature, the author generally does an excellent job placing this new work into the broader context of related studies over the past decade. Christopher Colose Research Scientist, SciSpace LLC, NASA Goddard Institute for Space Studies: The relevant framing concerning this work is not in gauging its “credibility,” since the research is sound and at the frontier of our knowledge of the topic. It will not, however, be the last word on the subject. The subject of how climate change affects mid-latitude weather at the synoptic scale (roughly the scale of ~1000 kilometers, i.e., smaller than the tropical scale circulation such as the Hadley cell, but much larger than a tornado for instance) is complex for a number of reasons. One reason is that these are some of the “noisiest” regions on the planet, somewhat less so in summer than in winter, but still subject to considerable internal variability. Therefore, for problems at the synoptic scale, it is often the case that initial condition uncertainty is of more importance than the expected forced component. Indeed, it is well known that 50 realizations of weather in a suite of model runs will not be in phase with reality’s weather, but even decadal trends in dynamical aspects of the mid-latitude atmosphere may differ among the 50 individual members of the model ensemble. Tim Woollings Lecturer, University of Oxford: This article has reported on this story well. The ideas in the new study are interesting, but much more detailed work on this is required in the future. I agree with the quote from John Fyfe that this study is really at the start of something rather than the end. I think climate scientists in general have very diverse views on this theory, but this is well reported in this article. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from the article; comments and replies are from the reviewers. As the climate warms, the Arctic is warming faster than the rest of the globe, potentially impacting the strength of the jet stream, which would have implications for midlatitude weather extremes. However, uncertainty remains regarding the magnitude and mechanisms of this effect, as it is at the frontier of scientific knowledge. “The Northern Hemisphere jet stream […] flow is stronger when that temperature difference is large. But when the Arctic warms up faster than the equator does […] the jet stream’s flow can become weakened and elongated. That’s when you can get the resultant weather extremes.” Daniel Swain Climate Scientist, University of California, Los Angeles: This is an accurate and succinct description of the primary hypothesized mechanism involved in the Arctic/mid-latitude weather linkage. Jim Kossin Research Scientist, NOAA's Center for Weather and Climate: Very nice description for the lay-audience. “Ever since 2012, scientists have been debating a complex and frankly explosive idea about how a warming planet will alter our weather — one that, if it’s correct, would have profound implications across the Northern Hemisphere and especially in its middle latitudes” Jim Kossin Research Scientist, NOAA's Center for Weather and Climate: This is a somewhat misleading intro. The debate has been focused on winter storms (as Mooney discusses below), and these new results are strictly for boreal summer/spring. “a warming planet causes our weather to become more stuck in place” Daniel Swain Climate Scientist, University of California, Los Angeles: This claim is somewhat overly confident given the available evidence. Observational studies (e.g. Francis and Vavrus 2015*) do indeed suggest that the “waviness” of the jet stream and subsequently the propensity for weather patterns to become more persistent has increased in certain regions and during certain seasons, although this is not universally true. There is also emerging evidence that the rapid warming of the Arctic may be playing a role in creating the conditions favorable for weather patterns to become “stuck in place”—a hypothesis that the new Mann et al. 2017* paper discussed in the article supports. The connections between amplified Arctic warming and mid-latitude weather extremes remains a very active area of scientific research (Overland et al. 2016*), however, and considerable uncertainty regarding the magnitude and mechanisms of this effect remain. Francis and Vavrus (2015) Evidence for a wavier jet stream in response to rapid Arctic warming, Environmental Research Letters Mann et al (2017) Influence of Anthropogenic Climate Change on Planetary Wave Resonance and Extreme Weather Events, Scientific Reports Overland et al (2016) Nonlinear response of mid-latitude weather to the changing Arctic, Nature Climate Change “This basic idea has sparked half a decade of criticism and debate, and at the cutting edge of research, scientists continue to grapple with it. And now, a new study once again reinforces one of its core aspects.” Daniel Swain Climate Scientist, University of California, Los Angeles: This is an accurate framing of the (sometimes contentious) ongoing scientific conversation regarding linkages between Arctic warming and mid-latitude weather. “‘This study goes beyond statistical correlations and explores a specific process that can plausibly explain how enhanced high-latitude warming trends may trigger remote weather impacts,’ he said.” Jim Kossin Research Scientist, NOAA's Center for Weather and Climate: Yes, this is the key here. The study is a step toward physically reconciling a linkage that’s only been described statistically. “But other scientific authors have expressed considerable skepticism of these kinds of ideas in the past. A recent study in Nature Geoscience, for instance, called into question whether the Arctic’s melting, and in particular its sea ice loss, has been causing winter cooling over Eurasia, another idea that has been swept up in the debate over the jet stream and weather extremes.” Jim Kossin Research Scientist, NOAA's Center for Weather and Climate: Again, the debate has been about Arctic amplification and winter storm behavior, so this is somewhat misleading. It gives the impression that the new study tacitly pushes the debate about the winter storms toward the Francis/Vavrus side. “‘I do not believe that this theory is fully developed or that the implications have been fully explored, but I do think that Mann et al. study is a very good start.’” Christopher Colose Research Scientist, SciSpace LLC, NASA Goddard Institute for Space Studies: I agree with this. There are many competing components involved in how the jet stream will change in the future, and changing pole-to-equator temperature gradients is just one (in fact, the pole-to-equator temperature gradient increases near the tropopause, complicating the physics). Elizabeth Barnes and James Screen have a good essay here that serves as a useful entry point into these complications. Jennifer Francis Senior Scientist, Woods Hole Research Center: I disagree that the study is only a beginning. The hypothesis that connects quasi-resonance with summer extreme weather, along with evidence to support it, began with Petoukhov et al (2013)*, which was then expanded upon by Coumou et al (2014)*, Kornhuber et al (2016)*, Petoukhov et al (2016)*, and now Mann et al (2017)*. Clearly there is more to learn, but in my view, we are well down the road to understanding this mechanism and identifying its signature in extreme weather. Petoukhov et al (2013) Role of quasiresonant planetary wave dynamics in recent boreal spring-to-autumn extreme events, PNAS Coumou et al (2014) Quasi-resonant circulation regimes and hemispheric synchronization of extreme weather in boreal summer, PNAS Kornhuber et al (2016) Evidence for wave resonance as a key mechanism for generating high-amplitude quasi-stationary waves in boreal summer, Climate Dynamics Petoukhov et al (2016) Quasiresonant amplification of planetary waves and recent Northern Hemisphere weather extremes, PNAS Mann et al (2017) Influence of Anthropogenic Climate Change on Planetary Wave Resonance and Extreme Weather Events, Scientific Reports

https://science.feedback.org/review/analysis-record-breaking-climate-change-pushes-world-uncharted-territory-damian-carrington-guardian/

1.5

The Guardian, by Damian Carrington, on 2017-03-20.

"Record-breaking climate change pushes world into ‘uncharted territory’"

This article in The Guardian describes a “State of the Global Climate” report for 2016 recently released by the World Meteorological Organization (WMO). The report highlights observations of global temperature, sea ice extent, and sea level rise, as well as notable weather patterns. Scientists who reviewed the article found that it accurately described climate trends and events mentioned in the WMO report, including record global warmth and notably low sea ice extents at both poles.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Timothy Osborn Professor, University of East Anglia, and Director of Research, Climatic Research Unit: Overall, this is an accurate and well-supported presentation of the significant nature of climate in 2016. I have highlighted a couple of statements that are overly confident/overstated, but most of the article is fine. Andrew King Research fellow, University of Melbourne: The article clearly and concisely documents some of 2016’s climate extremes and puts them in the context of the warming trend. Daniel Swain Climate Scientist, University of California, Los Angeles: Overall, the article accurately summarizes key points from the WMO report and places recent record-breaking climate events (such as unprecedented global heat and sea ice loss) into reasonable longer-term context. James Renwick Professor, Victoria University of Wellington: An excellent summary, mostly based on a report from the authoritative World Meteorological Organization. Some of the discussion (such as around sea level rise) cuts a few corners. Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: In general, the article is scientifically accurate and does not misrepresent things, although to be critical, given the title and angle of the piece it might be better to focus more on observational data and measurements from 2017, rather than citing many observations from 2016. Another possible criticism is that the piece also relies heavily on quotes and opinions from scientists rather than objective datasets or new graphic representations of those datasets. There aren’t many of the measurements that the WMO have cited included in the report, for example. Aimée Slangen Researcher, Royal Netherlands Institute for Sea Research (NIOZ): I think the article gives an accurate view of the WMO report, and it refers to other sources/papers to support the claims. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from the article; comments and replies are from the reviewers. 1.Human-caused global warming (along with El Niño conditions) lifted 2016 to the warmest year on record. “Global warming is largely being driven by emissions from human activities, but a strong El Niño – a natural climate cycle – added to the heat in 2016.” James Renwick Professor, Victoria University of Wellington: Yes, as stated in the last IPCC report, human emissions of greenhouse gases have been the dominant driver of climate change since the mid-20th century. No other changes (such as the output of the Sun) can adequately explain the observed warming. “But scientific research indicates the world was last this warm about 115,000 years ago and that the planet has not experienced such high levels of carbon dioxide in the atmosphere for 4m years.” Timothy Osborn Professor, University of East Anglia, and Director of Research, Climatic Research Unit: This statement is overly confident and not based on a broad consensus in the literature. Even the cited study states “we cannot be certain that the current year is warmer than any single year earlier in the Holocene due to centennial smoothing of the Holocene stack and original resolution of the underlying proxy records”. The most recent IPCC assessment indicates only moderate confidence that 1983-2012 was the warmest 30-year period in the last 1,400 years and limited this to the Northern Hemisphere rather than the global average. Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: Actually, some of the more recent estimates* have suggested that we may have crossed over the 400 ppm threshold briefly as recently as 2.4 million years ago, and again at 2.9 million years ago. (see Martinez-Boti et al.*). I think climate scientists typically think of the Pliocene (between about 5.3 and 2.6 million years ago) as being the last time period where CO2 may have been more or less permanently above the 400 ppm threshold though, so perhaps this is what they are referring to here. It might be advisable to tidy up the terminology a little here nonetheless. Martinez-Boti et al (2015), Plio-Pleistocene climate sensitivity evaluated using high-resolution CO2 records, Nature James Renwick Professor, Victoria University of Wellington: At the last interglacial period 115,000 years ago, increased solar intensity was responsible for the added warmth, but today’s high CO2 was last seen in the atmosphere 3-5 million years ago. At that time, global mean temperatures were a couple of degrees higher than present, and sea levels were several metres higher than present. “‘With levels of carbon dioxide in the atmosphere consistently breaking new records, the influence of human activities on the climate system has become more and more evident,’ said Taalas.” Mitch Lyle Professor, Sr. Research, Oregon State University: Readers should also be aware of the decades-long lag between the stabilization of CO2 in the atmosphere and the stabilization of CO2-induced warming. The planet will continue to heat because ocean temperatures will not yet be in equilibrium with the atmosphere. 2. Sea ice extent in both the Arctic and Antarctic have been exceptionally low in recent months. “El Niño is now waning, but the extremes continue to be seen, with temperature records tumbling in the US in February and polar heatwaves pushing ice cover to new lows.” Andrew King Research fellow, University of Melbourne: The El Niño pattern of sea surface temperatures waned quite a long time ago, with neutral conditions by mid-2016. The effects of the El Niño on the atmosphere persisted through the year, though. Daniel Swain Climate Scientist, University of California, Los Angeles: The fact that numerous high temperature and low sea ice records are still being exceeded in 2017, despite the lack of El Niño conditions in the Pacific Ocean, is indeed a testament to the increasingly strong human fingerprint upon global weather and climate events. James Renwick Professor, Victoria University of Wellington: This is especially striking in the Antarctic where sea ice extent has been increasing gradually for many years. We are now seeing historic lows in sea ice extent. Aimée Slangen Researcher, Royal Netherlands Institute for Sea Research (NIOZ): Decreasing sea ice extent has been mostly observed in the Arctic, but now also the Antarctic is showing declining sea ice extent. See this page for up to date observed sea ice extent and area. “‘Arctic ice conditions have been tracking at record low conditions since October, persisting for six consecutive months’” Timothy Osborn Professor, University of East Anglia, and Director of Research, Climatic Research Unit: Yes, this is supported by the observations, available at the NSIDC website. “‘The Arctic may be remote, but changes that occur there directly affect us. The melting of the Greenland ice sheet is already contributing significantly to sea level rise, and new research is highlighting that the melting of Arctic sea ice can alter weather conditions across Europe, Asia and North America.’” Daniel Swain Climate Scientist, University of California, Los Angeles: There is indeed observational evidence that melting of the Greenland ice sheet, which contributes to global sea level rise, has accelerated in recent years. While scientists are still intensively investigating the details, it is also true that recent research* suggests that the loss of Arctic sea ice will mostly likely influence weather patterns in mid-latitude regions (including much of Europe, Asia, and North America). Screen (2017)Far-flung effects of Arctic warming, Nature Geoscience 3.The article also mentions sea level changes, notable heat waves, and some of the societal implications of continued global warming. “The WMO’s assessment of the climate in 2016, published on Tuesday, reports unprecedented heat across the globe, exceptionally low ice at both poles and surging sea-level rise.” Timothy Osborn Professor, University of East Anglia, and Director of Research, Climatic Research Unit: “Surging” suggests that the faster sea level rise in 2016 has continued, whereas the surge was between Nov 2014 and Feb 2016, as indicated in WMO’s statement and in the data. “Global sea level rise surged between November 2014 and February 2016, with the El Niño event helping the oceans rise by 15mm.” James Renwick Professor, Victoria University of Wellington: A large part of this rise is related to the transition from La Niña to El Niño. The background rate of global sea level rise is still between 3-4mm per year. “Final data for 2016 sea level rise have yet to be published.” Aimée Slangen Researcher, Royal Netherlands Institute for Sea Research (NIOZ): Agreed, and the causes and reasons will need to be disentangled (El Niño/anthropogenic/other; ice/ocean/other). The total global mean sea-level record is publicly available through NASA’s website. “For example, the Arctic heatwaves are made tens of times more likely and the soaring temperatures seen in Australia in February were made twice as likely.” Andrew King Research fellow, University of Melbourne: This statement is referring to rapid attribution analyses that were conducted by the World Weather Attribution group. We found that the Arctic heat of late 2016 was made much more likely by human-induced climate change (although it remains a very unusual event in the current climate). In another analysis, we found the February heatwave in New South Wales was at least twice as likely to occur because of climate change. “‘Continued investment in climate research and observations is vital if our scientific knowledge is to keep pace with the rapid rate of climate change.’” James Renwick Professor, Victoria University of Wellington: Correct. We are learning as we go, observing how the climate is changing, but more effort is required to keep up with changes and to understand the physical processes at play. “Our children and grandchildren will look back on the climate deniers and ask how they could have sacrificed the planet for the sake of cheap fossil fuel energy, when the cost of inaction exceeds the cost of a transition to a low-carbon economy,’ Watson said.” Valentina Bosetti Professor, Bocconi University: There are large uncertainties surrounding the cost of inaction (i.e., what would be the monetary consequences of adapting to climate change were we not to mitigate its causes and keep emitting as we are doing today). Some of the physical impacts are estimated through projections which may be imperfect. There is large disagreement about what discount rate to use to value future climate damages1. Many of the consequences are simply hard to translate in monetary terms (non-market impacts). Some of the impacts may be nonlinear. This has lead multiple authors to consider abatement as a valuable tail-hedge insurance investment2,3. 1. Heal and Millner (2014) Agreeing to disagree on climate policy, PNAS 2. Weitzman (2014) Fat Tails and the Social Cost of Carbon, American Economic Review: 3. Drouet, Bosetti, and Tavoni (2015) Selection of climate policies under the uncertainties in the Fifth Assessment Report of the IPCC, Nature Climate Change

https://science.feedback.org/review/great-barrier-reef-coral-climate-change-dieoff-the-new-york-times-damien-cave-justin-gillis/

1.8

The New York Times, by Damien Cave, Justin Gillis, on 2017-03-15.

"Large Sections Australia’s Great Reef Are Now Dead, Scientists Find"

The New York Times published an article on coral bleaching and mortality in the Australian Great Barrier Reef and the influence of climate change. Scientists who reviewed the article deemed it largely accurate. While last year saw a record bleaching event that ended up damaging a record number of corals in the region. Severe bleaching has continued for a second consecutive year, which is unprecedented. While natural temperature fluctuations (due to El Niño, for example) have always occurred, they are now superimposed on a warmer background due to human-induced global warming. That causes mass coral bleaching to happen more frequently. Under a business-as-usual scenario of greenhouse gas emissions, coral reef ecosystems are expected to undergo major losses as their slow development and habitat requirements prevents fast migration towards cooler regions.See all the scientists’ annotations in context This is part of a series of reviews of 2017’s most popular climate stories on social media.GUEST COMMENTS: Ove Hoegh-Guldberg Professor and Director, Global Change Institute, University of Queensland: This is an important article that relates the latest science. Even though people may find it shocking, we are facing a serious downward trend in the world’s largest continuous coral reef system. John Bruno Professor, The University of North Carolina at Chapel Hill: Overall, this was an accurate article. There were three sentences that was just a tad off—to be clear, these are minor quibbles (see below). Simon Donner Associate Professor, The University of British Columbia: The article accurately depicts the scientific consensus on climate change and coral bleaching. Mark Eakin Scientist, Coordinator of NOAA’s Coral Reef Watch, National Oceanic and Atmospheric Administration: It is a very nice article. A couple of spots are a bit overstated but this article appears well-researched and carefully worded. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from the article; comments and replies are from the reviewers. 1.Australia’s Great Barrier reef experienced an extensive coral bleaching event last year dueto warming oceans. “Huge sections of the Great Barrier Reef, stretching across hundreds of miles of its most pristine northern sector, were recently found to be dead, killed last year by overheated seawater.” For validation, see our previous analysis of an article in USA Today titled “Australia’s Great Barrier Reef has worst coral die-off ever”. “An additional kick was supplied by an El Niño weather pattern that peaked in 2016 and temporarily warmed much of the surface of the planet, causing the hottest year in a historical record dating to 1880.” John Bruno Professor, The University of North Carolina at Chapel Hill: This is a very common misconception even among scientists. The warming, bleaching, and coral loss is 100% due to greenhouse gas emissions, not the ENSO cycle and the fact that we were in a peak of the El Niño phase in early 2016. The Great Barrier Reef has experienced El Niño events for thousands of years, yet bleaching wasn’t observed there until 1998 when ocean warming pushed ocean temperatures just above the bleaching threshold. 2. Some corals could potentially migrate to cooler waters, but the rapid pace of warming means most coral will be lost. “The global reef crisis does not necessarily mean extinction for coral species. The corals may save themselves, as many other creatures are attempting to do, by moving toward the poles as the Earth warms, establishing new reefs in cooler water.” Simon Donner Associate Professor, The University of British Columbia: Minor quibble: the article mentions corals potentially migrating towards the poles. While coral species may spread poleward as the ocean warms, it takes many years for the reef structure to grow, thus the habitat for other reef species may not be easily recreated. Mark Eakin Scientist, Coordinator of NOAA’s Coral Reef Watch, National Oceanic and Atmospheric Administration: This is rather overstated. While some weedy species may migrate poleward, studies have shown that corals cannot move to much higher latitude due to other factors, such as the light corals require for photosynthesis and skeletal growth. Higher latitude corals will also be restricted to shallow water where they are more susceptible to cold stress. Kleypas et al (1999) Environmental Limits to Coral Reef Development: Where Do We Draw the Line?, American Zoologist “If water temperatures stay moderate, the damaged sections of the Great Barrier Reef may be covered with corals again in as few as 10 or 15 years” John Bruno Professor, The University of North Carolina at Chapel Hill: First, they aren’t moderate now. If they were to decrease and not exceed the bleaching threshold for another few decades, there would be some coral recovery. Second, 10-15 years is a big stretch. There would be some recovery, but not total recovery, especially of very long-lived slow-growing species. “Within a decade, certain kinds of branching and plate coral could be extinct, reef scientists say, along with a variety of small fish that rely on them for protection from predators.” John Bruno Professor, The University of North Carolina at Chapel Hill: I think it is very unlikely any corals would be extinct in a decade. The problem isn’t threat of extinction, its loss of habitat for other critters when corals bleach and die. The corals become less dense, but there will still be many millions of colonies for most species.

https://science.feedback.org/review/why-are-climate-change-models-so-flawed-because-climate-science-is-so-incomplete-jeff-jacoby-boston-globe/

-2

The Boston Globe, by Jeff Jacoby, on 2017-03-14.

"Why are climate-change models so flawed? Because climate science is so incomplete"

An article by Boston Globe columnist Jeff Jacoby argues that climate science is too “incomplete” to determine whether human-caused emissions of greenhouse gases like carbon dioxide could be responsible for global warming. The column defended US EPA Administrator Scott Pruitt’s recent statement that he “would not agree that [human activity is] a primary contributor to the global warming that we see”—a statement scientistsreviewed and found to be incorrect. Scientists who analyzed Jacoby’s column found that it is inaccurate, misleading, and uses flawed reasoning to support its central claims. In reality, CO2’s role in the climate system is well understood, and this fundamental knowledge informs the determinations that humans are responsible for modern climate change, and that continued greenhouse gas emissions will cause further warming.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. James Screen Associate Professor, University of Exeter: This is a highly inaccurate article that makes a number of false and intentionally misleading claims. The weight of scientific evidence (summarised in the IPCC reports) shows that greenhouse gas emissions are the dominant cause of observed global warming. The claim that climate models “always predict far more warming” is demonstrably false. The discussion of complexity is intended to mislead: the fact that the climate system is incredibly complex does not mean we don’t understand key aspects of how it functions. Mitch Lyle Professor, Sr. Research, Oregon State University: Jacoby used a flurry of words to claim that models did not work. He set up a straw man about complexity that was irrelevant and never actually examined real climate models. Dan Chavas Assistant Professor, Purdue University: The article is full of logical fallacies: just because a system has many moving parts does not mean it is unpredictable. Alexis Tantet Postdoctoral researcher, Hamburg University, Meteorologisches Institut: The facts given by the author regarding the skills of climate models and the state of the art are mostly wrong. The most important processes are not understood by the author and his logic is flawed William Seviour Senior Lecturer, University of Exeter: This article combines tired and regularly-debunked climate myths with faulty reasoning to support a statement which is ungrounded in scientific reality. James Renwick Professor, Victoria University of Wellington: One of the most egregious pieces of misinformation I have seen in the media in years. Ilissa Ocko Climate Scientist, Environmental Defense Fund: This article employs flawed reasoning mixed with inaccurate statements to create a false impression of climate scientists’ state of understanding. Andreas Schmittner Associate Professor, Oregon State University: The article contains major scientific inaccuracies and it omits important information. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from the article; comments and replies are from the reviewers. 1. It is clear that humans are causing climate change through emissions of greenhouse gases like carbon dioxide, which acts as a control knob on the climate system. “CO2 is certainly a heat-trapping greenhouse gas, but hardly the primary one: Water vapor accounts for about 95 percent of greenhouse gases. By contrast, carbon dioxide is only a trace component in the atmosphere: about 400 ppm (parts per million), or 0.04 percent.” Christopher Colose Research Scientist, SciSpace LLC, NASA Goddard Institute for Space Studies: First, it is true that water vapor constitutes the bulk of Earth’s present-day greenhouse effect (measured in terms of infrared absorption). Quantitatively, however, Jacoby is off by quite a bit. In fact, water vapor constitutes ~50% of the terrestrial greenhouse effect, not 95% (see here*). Clouds (solid and liquid water that form when the vapor condenses) constitute another ~25%, but CO2 contributes to almost all of the remaining fraction (only ~5% or so from all of the other combined gases). This is because CO2 still absorbs well in spectral regions where water vapor doesn’t, and also because the upper troposphere is very dry; the ability to absorb intense surface emission and re-emit it at colder, higher layers of the atmosphere is critical for the maintenance of a planetary greenhouse effect. Secondly, the water vapor greenhouse effect is not independent of the CO2 in the atmosphere. Jacoby stresses that CO2 is only a trace component of the atmosphere, an argument that is irritatingly unoriginal and provides useless context when describing the flow of radiation through the atmosphere. As before, CO2 accounts for ~20% of Earth’s greenhouse effect. N2 and O2 account for nearly all of Earth’s atmospheric mass. However, if the atmosphere were purely N2 and O2, the planet would likely be in a snowball state due to the lack of greenhouse trapping. This is where the equations of radiative transfer must be applied, rather than a naive intuition about proportions. Schmidt et al (2010)Attribution of the present-day total greenhouse effect,Journal of Geophysical Research: Atmospheres. Mark Zelinka Research Scientist, Lawrence Livermore National Laboratory: Another helpful quote comes from this article: “The contribution of CO2 to the greenhouse effect, considerable though it is, understates the central role of the gas as a controller of climate. The atmosphere, if CO2 were removed from it, would cool enough that much of the water vapor would rain out. That precipitation, in turn, would cause further cooling and ultimately spiral Earth into a globally glaciated snowball state. It is only the present of CO2 that keeps Earth’s atmosphere warm enough to contain much water vapor.” I like to think of CO2 as analogous to a military commander and water vapor as analogous to an army of foot soldiers. Even though the water vapor foot soldiers do most of the fighting, the CO2 commander sends the army to battle. William Seviour Senior Lecturer, University of Exeter: While it is true that carbon dioxide constitutes about 400 ppm (or 0.04%) of the atmosphere, the implication that this means it is insignificant in Earth’s climate is incorrect. It is the ability of a gas to absorb radiation, and so affect energy balance of the Earth, not its concentration, which is important. This effect on Earth’s energy balance can be quantified by the radiative forcing (RF); a positive RF means a surface warming effect and a negative RF a cooling. The figure below, from the 2013 IPCC report shows estimates of RF for a range of factors which have influenced climate from 1750-2011. As can be seen, increasing carbon dioxide concentrations have the largest RF and therefore the largest impact on climate. I also stress that knowledge of the important role of carbon dioxide (despite its low concentration) in Earth’s climate is not new, and dates back to the work of Tyndall, Arrhenius, and others in the 19th century. “Moreover, its warming impact decreases sharply after the first 20 or 30 ppm. Adding more CO2 molecules to the atmosphere is like painting over a red wall with white paint — the first coat does most of the work of concealing the red. A second coat of paint has much less of an effect, while adding a third or fourth coat has almost no impact at all.” Christopher Colose Research Scientist, SciSpace LLC, NASA Goddard Institute for Space Studies: Jacoby emphasizes the logarithmic nature of how CO2 affects the energy balance of Earth, and hence surface temperature (i.e., going from 10 ppm of CO2 to 11 ppm would have a much larger impact than going from 300 to 301 ppm). This is correct, but has been known for well over half a century now, and is fully accounted for in even simple estimates of future warming. This is therefore a distraction. Andreas Schmittner Associate Professor, Oregon State University: The effects of CO2 do not decrease sharply after the first 20 or 30 ppm. The radiative effects of CO2 are logarithmic, so they increase slightly less the higher CO2 gets but they don’t decrease sharply. Ilissa Ocko Climate Scientist, Environmental Defense Fund: This is flawed reasoning as it is not a sensible analogy for how the greenhouse effect works. The science is more complex: Namely, radiation from the surface at a warmer temperature is absorbed in the layers above which are at a colder temperature; the colder layers emit less radiation so that there is a net loss of radiative energy escaping to space from the atmosphere-surface system as a whole, but coming about due to the “exchange” as formulated. This is true in absorption bands that are transparent and not opaque—i.e., in bands that are not saturated. In bands that are opaque, the radiation emanating from the layer to space represents a “cooling-to-space” and this too represents a “trapping”. In this regard, the lapse-rate and decrease of temperature with height (in the troposphere) are important. The more CO2 that is added to the atmosphere, the more heat that is “trapped” in the climate system, although it is not 1:1 and is instead a logarithmic relationship. However, regardless of the rate, we still have more warming with more CO2—that is unequivocally true. William Seviour Senior Lecturer, University of Exeter: Jacoby links to a blog page which explains the logarithmic relationship of CO2 concentrations and radiative forcing. Contrary to Jacoby’s implication, this is actually a well accepted part of climate science. For instance, see Myhre et al 1998* (table 3), who give detailed estimates of this logarithmic relationship. However, as CO2 concentrations rise, the fraction of CO2 which remains in the atmosphere (rather than being absorbed by the ocean) is projected to increase (see Jones et al 2013*). The net effect is that the relationship between total CO2 emissions and surface temperature is almost linear. See the figure below from the 2013 IPCC report. Myhre et al (1998) New estimates of radiative forcing due to well mixed greenhouse gases, Geophysical Research Letters Jones et al (2013) Twenty-First-Century Compatible CO2 Emissions and Airborne Fraction Simulated by CMIP5 Earth System Models under Four Representative Concentration Pathways, Journal of Climate “There is a popular theory that atmospheric CO2 amplifies the creation of water vapor, thereby increasing warming through a ‘positive feedback loop.’ But that theory so far is mostly speculative; climate projections using models based on it have consistently failed, nearly always predicting far more warming than has occurred” John Fyfe Senior Research Scientist, Canadian Centre for Climate Modelling and Analysis: [John Fyfe was the first author of the paper linked by Jacoby to support this claim] The statement “climate projections using models based on it have consistently failed, nearly always predicting far more warming than has occurred” is false. Climate models reproduced the observed record of global average temperature rise since the middle of the 20th Century. It is true that climate models overestimated the observed rate of warming over the early-21st Century but this was not unexpected. Over this period, and due to a well-known natural fluctuation in the climate system, temperatures over much of the tropical Pacific were cooler than normal. These ocean temperatures have warmed significantly over the past few years. Climate models represent these natural fluctuations in the climate system but do not – by design – reproduce the observed timing except by chance. This is the primary reason why climate models overestimated the rate of global average temperature rise over the early-21st Century. Christopher Colose Research Scientist, SciSpace LLC, NASA Goddard Institute for Space Studies: Jacoby discusses the so-called water vapor feedback, in which warming caused by CO2 (or anything) results in more water vapor in the atmosphere, increasing heating. However, his discussion is confused. First, models are not based on a water vapor feedback. Such a feedback is result, not an assumption. There is no FORTRAN code written that tells a model to increase the water vapor concentration when the CO2 is going up. However, there is incredibly well-established thermodynamics assuring us that a warmer atmosphere can theoretically hold more water vapor. This doesn’t mean it will—after all, deserts are very hot, but not very moist. This is because atmospheric dynamics (especially the rising and sinking motions of air) keep most of Earth’s atmosphere beneath its maximum vapor holding capacity. However, it turns out that observations and complex models (as well as more simple theoretical work) suggest that this degree of “subsaturation” (or relative humidity) doesn’t change much, so the actual water vapor concentration still goes up in a similar way that it would if it just behaved like a simple thermodynamic equation (see e.g., here and here and here)*. Indeed, this has been a robust result going back to at least the 1960s in observational and model-based syntheses of the problem, and is now very well understood. Indeed, CO2 is the fundamental control knob on Earth’s climate over relatively long timescales, since the water vapor concentration is shackled to temperature in a very fundamental way, because the Sun’s output does not change very much except on geologic time intervals, and because CO2 is the principle non-condensing greenhouse gas capable of changing in response to geologic (or anthropogenic) sources and sinks on climate timescales. Pierrehumbert et al (2007) On the relative humidity of the Earth’s atmosphere, The General Circulation Held and Soden (2000) Water vapor feedback and global warming, Annual Review: of Energy and the Environment Chung et al (2014) Upper-tropospheric moistening in response to anthropogenic warming, PNAS Andreas Schmittner Associate Professor, Oregon State University: The water vapor feedback, which is referred to here as “creation of water vapor” but in fact is higher water vapor in a warmer atmosphere, is a basic prediction of thermodynamics, one of the most well-tested branches of physics. Water vapor has been observed to increase*. So, there is nothing speculative about it. The claim that climate models have consistently failed is false. In fact, the contrary is true. Climate model projections from the 1980s have essentially come true. For a recent example see Stouffer and Manabe (2017)*. Chung et al (2014) Upper-tropospheric moistening in response to anthropogenic warming, PNAS Stouffer and Manabe (2017) Assessing temperature pattern projections made in 1989, Nature Climate Change Mark Zelinka Research Scientist, Lawrence Livermore National Laboratory: All available evidence suggests that the atmosphere maintains nearly constant relative humidity, meaning that the absolute concentration of water vapor increases exponentially with temperature. The exponential increase is grounded in fundamental physics known as the Clausius-Clapeyron equation. A particularly clever test of the amplifying water vapor feedback was conducted in response to the Mount Pinatubo eruption in 1991*. If there were no amplifying water vapor feedback, then the global cooling in response to the volcanic eruption would have been much smaller than observed. Soden et al (2002) Global Cooling After the Eruption of Mount Pinatubo: A Test of Climate Feedback by Water Vapor, Science “The science is far from settled.” James Renwick Professor, Victoria University of Wellington: The basic controls on the climate, sunlight and greenhouse gases, have been understood for over a century and are not disputed. The frontiers of climate research are where the debates lie, as with any branch of science. “[Pruitt’s statement] was an accurate and judicious answer” Ilissa Ocko Climate Scientist, Environmental Defense Fund: It is objectively not an accurate answer and is misleading at best. [Pruitt’sstatement has beenreviewed by scientists with Climate Feedback and found to be incorrect.] While it is certainly challenging to determine human influence on the climate, decades of research by tens of thousands of scientists from different institutions all over the world have yielded a nearly unanimous consensus with extreme confidence that humans are the dominant cause of climate change. In fact, scientists have been questioning and researching human influence on the climate for nearly 200 years. Further, we can use techniques similar to the smoking-cancer causality research to prove that humans are mainly responsible and to show that carbon dioxide is the primary control knob for today’s climate change. There is no “tremendous disagreement” or “debate” about this. 2. Earth’s climate system is complex, but the basic processes are well understood, allowing climate scientists to usefully project the impacts of continued greenhouse gas emissions. “Earth’s climate system is unfathomably complex. […] The more variables there are in any system or train of events, the lower the probability of all of them coming to pass. Your odds of correctly guessing the outcome of a flipped coin are 1 in 2, but your odds of guessing correctly twice in a row are only 1 in 4 — i.e., ½ x ½ Extending your winning streak to a third guess is even less probable: just 1 in 8.” James Renwick Professor, Victoria University of Wellington: Yes, it is complex, but not unfathomable. The basics are simple—the energy budget at Earth’s surface is controlled by the intensity of sunlight reaching the ground and the amount of greenhouse gas in the atmosphere. That’s it. This analogy implies everything is happening randomly in the climate system. This is not the case. There is a great deal of structure imposed by the laws of fluid motion and energy transfer, and by the basic geometry and rotation rate of the Earth. Alexis Tantet Postdoctoral researcher, Hamburg University, Meteorologisches Institut: The Earth system is indeed complex with nonlinear interactions between various components on a large range of time and spatial scales. However, some processes are very robust, such as the response of the global energy budget to increased greenhouse gases, so that the surface of the Earth eventually has to warm up in order to reach a radiative balance. The distribution of the heating, the rate of melting of the ice sheets, the changes in the occurrence of extremes, etc. are more difficult to predict and that is why we need state-of-the art global climate models. Last, one should not confuse the weather prediction of an exact meteorological state, limited by the chaotic nature of the system, and climate projections of the statistics of variables in response to forcing, such as the global mean surface temperature sensitivity to greenhouse gases emissions. “The list of variables that shape climate […] would run to hundreds, if not thousands, of elements, none of which scientists would claim to understand with absolute precision.” Mitch Lyle Professor, Sr. Research, Oregon State University: Jacoby is making a laundry list, not trying to understand the issues. He is also confusing the issue by trying to claim that since scientists cannot predict climate change at a given small location at a fixed point in future time that they do not have the ability to generally predict the the future trend. Climate scientists are after the trend. Most of the variables he mentions cause the local climate to deviate to a small extent from the trend. Some, like volcanic activity or El Niño, affect the climate for a small number of years, and then their effect disappears. Christopher Colose Research Scientist, SciSpace LLC, NASA Goddard Institute for Space Studies: The basic argument in the remainder of the article is one of “complexity” and the notion that climatologists cannot perfectly understand thousands of variables, and hence the behavior of the system under investigation. Jacoby is not completely wrong—climate is extremely complex, and poses no shortage of interesting research questions. However, it is sometimes difficult for non-specialists to appreciate the emergent simplicity that can arise in an incredibly complex system. After all, how do we know summer will be warmer than winter, that the top of Mt. Everest is colder than the base, or that Arizona is expected to be on average drier than Florida, or that the equator ought to be hotter than New York, or that the climate will cool following a large volcanic eruption? These statements are not just based on prior observations, but in fact can be predicted by applying fundamental equations to a rotating planet. Part of the beauty in studying atmospheric science is in gaining an appreciation for where complexity is counterbalanced by an almost eerie predictability, much like how the outcome of a single spin in roulette is hopelessly unpredictable (and certainly influenced by every slight detail at the time the dealer releases the ball), but casinos have no problem with such complexity because the statistical behavior of the roulette wheel is well-posed. Similarly, the statistical behavior of the atmosphere, while unsolved, is not actually that complex. The appeal to complexity is a compelling one. Nonetheless, progress has been made in many complex sciences (astrophysics, geology) in which the system under investigation cannot be experimentally isolated, and yet where so much is known. However, it turns out to be incredibly simple to rule out El Niño, volcanic eruptions, soil quality, sunspot cycles, plate tectonics, etc. to the trend in global temperatures since 1950. Just as geologists can inform you of the glacial history of a region, sometimes with little more than a trained eye, CO2 leaves behind “fingerprints” in the atmospheric warming that other “forcing agents” do not. Another perhaps surprising component is that this result is not extremely sensitive to unknown variables. Suppose, for example, that the Andes Mountains were abruptly flattened. This would almost certainly affect important aspects of the global and regional climate, but many of the critical phenomena of the climate system (e.g. that the equator is wet where air rises, that storm tracks develop in the mid-latitudes, the presence of a jet stream, etc.) would still remain. Furthermore, adding CO2 to a “flat-Andes hypothetical Earth” would still result in warming. It’s physics, and it’s unavoidable. It is true that the exact magnitude of future warming, even if we knew future carbon emissions perfectly, is still not known to within even 10%. However, that uncertainty range does not overlap with “very little warming” or “make the planet uninhabitable warming.” In any case, if one’s argument is based on how complex the system is, surely perturbing that complex system is not something they ought to advocate for! “What are the odds that a climate model built on a system that simple would be reliable? Less than 50/50. (Multiplying .95 by itself 15 times yields 46.3 percent.)” James Renwick Professor, Victoria University of Wellington: Again, this assumes that all variables are independent and everything is happening randomly. This is just not the case. Winds, temperatures, pressures, cloud formation, and so on are all bound together in coherent ways by the laws of physics. Alexis Tantet Postdoctoral researcher, Hamburg University, Meteorologisches Institut: This is absolutely not how prediction skills are and should be measured. Assuming that each variable is given the same weight, the initial error would be of 5%. How this error grows with the prediction is a nontrivial problem, which cannot be explained by kindergarten probabilities, but requires observations, theory and modeling. Moreover, the problem of the predictability of fast weather fluctuations become irrelevant for long-term climate projections of statistics in response to forcing. “Is it any surprise that climate-change predictions in the real world — where the complexities are exponentially greater and the exactitude of knowledge much less — have such a poor track record?” William Seviour Senior Lecturer, University of Exeter: One way we can evaluate climate models is their ability to simulate past observed climate changes. The following figure from the 2013 IPCC report shows that they in fact have a good track record in capturing climate change over past century.

https://science.feedback.org/review/claim-new-scientist-humans-responsible-100-warming-mostly-correct/

Mostly correct

New Scientist, Michael Le Page, 2017-03-08

more than 100 per cent of the warming over the past century is due to human actions

Overstates scientific confidence: The statement gives the impression of high confidence in this exact number, while a little more caution is warranted.

The best estimate of the portion of global warming observed since 1950 that is due to human influence is indeed around 100%. There is some uncertainty as to whether humans caused a little bit more or a little bit less than 100% of the warming.

... more than 100 per cent of the warming over the past century is due to human actions. How can it be more than 100 per cent? Because without us the planet would likely have cooled very slightly thanks to natural factors such as volcanic emissions and orbital changes.

Andrew King Research fellow, University of Melbourne: While I wouldn’t go quite as far as saying more than 100% of warming is due to human activities (because there are uncertainties on these numbers and it may be just under 100%) the point the writer is trying to make is essentially correct. Without human influences on the climate we would have had virtually no trend in global temperatures so all of the warming since about 1950 can be attributed to the human influence on the climate.Francois-Marie Breon Senior Scientist, Commissariat à l'Energie Atomique: There is no doubt that human activities led to climate warming during the last 100 years. The contribution of natural processes (the sun, volcanoes, natural variability…) is small in comparison. However, there is significant uncertainty on the natural contribution and it is not yet clear whether the Earth would have warmed or cooled during the past century without the anthropogenic perturbation. Thus, the anthropogenic contribution to the observed warming is close to 100%, but it is not demonstrated whether it is larger or smaller than this number.Andreas Schmittner Associate Professor, Oregon State University: I’d say that the statement is mostly correct. The only difference between the statement and the study it is hyperlinked to is that the study considers the temperature trend from 1950 to 2010, so the last 60 years and not the past century as noted in the statement. I’d also note that the cooling due to natural factors is not statistically significant in the study.From the IPCC’s Fifth Assessment Report: “It is extremely likely that more than half of the observed increase in global average surface temperature from 1951 to 2010 was caused by the anthropogenic increase in [greenhouse gas] concentrations and other anthropogenic forcings together. The best estimate of the human-induced contribution to warming is similar to the observed warming over this period.” Figure showing the best estimate of the human-induced contribution to warming between 1951 and 2010. Black lines show confidence intervals.

https://science.feedback.org/review/science-shows-humans-primarily-responsible-climate-change-counter-epa-administrator-scott-pruitts-claim/

Incorrect

CNBC, Scott Pruitt, 2017-03-09

I would not agree that [carbon dioxide is] a primary contributor to the global warming that we see.

Misleading: While there is uncertainty about the precise value of the human contribution to global warming, that uncertainty does not include the possibility that human activities are not the primary contributor. Factually inaccurate: There is no significant scientific disagreement about the fact that human activity is responsible for climate change.

Science clearly shows that the climate change that has occurred since the Industrial Revolution is primarily due to human-caused emissions of greenhouse gases.

I think that measuring with precision human activity on the climate is something very challenging to do and there’s tremendous disagreement about the degree of impact. So no, I would not agree that it’s a primary contributor to the global warming that we see.

This is part of a series of reviews of 2017’s most popular climate stories on social media.Andy Pitman Director of the ARC Centre of Excellence for Climate System Science, The University of New South Wales: Its an incorrect statement because it convolutes three statements. “I think that measuring with precision human activity on the climate is something very challenging to do” This statement is true. It is very challenging, but 30 years of intense effort by a vast array of scientists have done it. “and there’s tremendous disagreement about the degree of impact.” This statement is false in terms of the implications of the decision. That is, there is no scientifically well-informed disagreement that the impact will be significant and should be built into any sensible risk management. It is true that there is disagreement on the degree of impact, but not that the impact will be significant. To be clear, there is agreement that the impact will be very serious, but how very serious is argued. “So no, I would not agree that it’s a primary contributor to the global warming that we see.” That statement is inconsistent with every independent assessment of the scientific literature I have seen, except from organisations set up to deny the science and misinform the public. The statement that global warming is unequivocal is supported by a massive body of work. The main statement comes from the 5th assessment report by the Intergovernmental Panel on Climate Change, a report agreed to by the global scientific community, and by the world’s governments. Shaun Lovejoy Professor, McGill University: Let’s say you are given only three pieces of information: a) The annual average value of the global temperature from 1880 to 1909 b) The atmospheric CO2 concentration for each year c) The effective climate sensitivity With only this, the temperature over the 104 years between 1909 and 2013 could be incredibly well forecast (black line in the figure below), indeed to about an accuracy of ±0.22 °C (purple lines, 90% confidence limits). This tight limit includes the so-called “pause” of the early 2000s. Knowing only the CO2 therefore allows us to predict the temperature more than 100 years into the future. Given that the total change over this time was 1.1 °C, the prediction is correct to within 20%. We know that the CO2 was anthropogenic, therefore its increase was not caused by a change of temperature. We can conclude that CO2 is responsible for much of the change in temperature over the last century. Figure adapted from Lovejoy (2015), Using scaling for macroweather forecasting including the pause, Geophysical Research Letters Ed Hawkins Principal Research Fellow, National Centre for Atmospheric Science: John Tyndall measured the heat absorption properties of various gases, including carbon dioxide, in his laboratory in the 1850s and suggested that changing their atmospheric concentrations would alter the climate. The levels of carbon dioxide have increased ever since and Tyndall’s prediction has become a reality. Global temperatures have risen by about 1°C, causing sea ice and land ice to melt, sea levels to rise, and extreme heatwaves and rainfall to increase. The impacts of increasing levels of carbon dioxide in the atmosphere are being seen already and the risks for the future are considerable unless we stabilise our emissions of greenhouse gases.

https://science.feedback.org/review/scientists-we-know-what-really-causes-climate-james-barrett-the-daily-wire/

-1.5

The Daily Wire, by James Barrett, on 2017-02-24.

"Scientists: Here's What Really Causes Climate Change (And It Has Nothing To Do With Human Beings)"

This post at The Daily Wire, which has been widely shared on Facebook, claims that a recent study of variations in Earth’s orbit recorded by 90 million-year-old rocks provides evidence against a human cause of current global warming. Scientists who reviewed the post found that it misrepresented the study’s implications for modern climate change, as well as the timeframes that the study is relevant to. In reality, the gradual cycles in Earth’s orbit are much too slow to be responsible for the warming of the last couple centuries. Climate research has shown that these orbital changes and other natural factors do not explain modern warming. All the reviewers also indicate that the title of the article is not supported by its content.See all the scientists’ annotations in contextUPDATE (07 March 2017): The original article has been edited to correct some of the statements highlighted here. Read moreREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Francois-Marie Breon Senior Scientist, Commissariat à l'Energie Atomique: Although the main body of the article may be a fair description of a scientific paper, the conclusion that anthropogenic climate change is dwarfed by natural variations is extremely misleading and certainly not in the original paper. The original scientific paper discusses climate variations over millions of years. The causes for recent climate change involves processes that are very different. Georg Feulner Senior Scientist, Potsdam Institute for Climate Impact Research (PIK): The reasoning in this biased article is flawed. The fact that orbital variations can cause climate change does not imply “that the role man plays on the planet is dwarfed by natural phenomena”. Chris Brierley Senior Lecturer, University College London: It’s strange how research into how planets orbit within our solar system has ended up being used to downplay the anthropogenic role in climate change. The research is about a geologic time period without ice-ages, yet that seems to be the confused reasoning for the article’s conclusion. The incorrect link to completely different research in the Nature journal about ice-ages betrays this confusion. Geert Jan van Oldenborgh Senior researcher, KNMI (The Royal Netherlands Meteorological Institute): The article misuses a Nature article on a geological process 90 millions years ago to argue the warming of the past century is not anthropogenic. It seems the reasoning is ideologically motivated rather than based on reality. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from the article; comments and replies are from the reviewers. 1.The timing of past “ice ages” was governed by slow-changing cycles in Earth’s orbit, but these cycles can not explain recent warming, which has been caused by human activities, instead. “While evidence that the earth’s orbital variations impact radiation levels and thus global temperatures does not of course mean that man is not in some way impacting the climate, studies like these highlight that the role man plays on the planet is dwarfed by natural phenomena utterly out of our control.” Geert Jan van Oldenborgh Senior researcher, KNMI (The Royal Netherlands Meteorological Institute): Over geological time scales, indeed. However, the rise in temperature of 1 degree Celsius over the last two hundred years is not on a geological time scale, and is not caused by natural phenomena out of our control as suggested here. Both from the negative (there are no natural forcings on the climate that would have produced such heating over the last century) and from the positive (the heating is pretty much what we expect from greenhouse gases minus aerosols) the evidence is very strong that humans are responsible for most of the trend over the last 100 years. Chris Brierley Senior Lecturer, University College London: I’m not sure how they come to this conclusion. The increase in global temperature from the depth of the last glacial (22,000 years ago) to preindustrial times is about 4.5°C. This is less than the warming projected for the end of the century, if we choose to ignore man’s responsibility as the author suggests. Clearly if we do act to limit the warming to 2°C, then the glacial change would be bigger than it, but the timespans involved mean that current climate change is still a happening at a faster rate. “[…]an explanation of the fluctuations of the earth’s temperatures that global warming alarmists are going to make sure to bury: The cycle of changes in the climate over the millennia is a result of changes in the amount of solar radiation, in part caused by small changes in the orbits of Earth and Mars.” Chris Brierley Senior Lecturer, University College London: This is the accepted explanation for periodic past changes in Earth’s climate. We spend multiple classes explaining this to our students. We certainly do not bury it. “changes in the climate over the millennia” Geert Jan van Oldenborgh Senior researcher, KNMI (The Royal Netherlands Meteorological Institute): This is false. The article is about changes in climate 90 million years ago at geological time scales, much slower than the “millennia” referred to here. 2.The article seems to confuse two different studies. “While the notion that the impact on earth’s orbital cycle on solar radiation levels is the most significant factor determining global temperatures is anything but new, the team of scientists seem to have tied the phenomenon to planetary orbits in a more concrete manner than previous studies.” Chris Brierley Senior Lecturer, University College London: I can’t help but think this sentence really refers to a research article called “A simple rule to determine which insolation cycles lead to interglacials” by Tzedakis and colleagues, rather than “Theory of chaotic orbital variations confirmed by Cretaceous geological evidence” by Ma, Meyers & Sageman. “In an article summarizing the scientists’ findings, which were originally published this week in the journal Nature, the University of Wisconsin-Madison notes that the study ‘provides the first hard proof for what scientists call the ‘chaotic solar system,’ a theory proposed in 1989 to account for small variations in the present conditions of the solar system.” Chris Brierley Senior Lecturer, University College London: Neither the linked article nor this Daily Wire news item relate to the research linked in Nature [which is the Tzedakis et al paper rather than Ma et al].

https://science.feedback.org/review/heres-why-its-so-frickin-hot-right-now-andrew-freedman-mashable/

1.3

Mashable, by Andrew Freedman, on 2017-02-24.

"Here’s why it's so frickin’ hot right now"

This article at Mashable discusses the number of high temperature records set in the United States during the month of February. While short-term weather events are not indicative of climate changes, the statistics of weather events across regions and over time doreflect climatic trends. As the climate warms due to human activities, daily high temperature records will be set more frequently than new low temperature records. The scientists who reviewed this article found that it accurately described recent US weather within this context.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Andrew King Research fellow, University of Melbourne: The article provides an overview of the recent record-breaking warm weather in parts of the US. It is well-researched and points to the most relevant literature in the field. In the absence of a specific event attribution study we cannot quantify the role of climate change in this event. However, by pointing to the long-term trend in the ratio of record-setting, the article does a nice job of putting this event in the context of a warming world. Ryan Sriver Associate Professor, University of Illinois: This is a well-written piece that provides a nice summary of the current warm events in the bigger context of climate change. I caution against using a single month of data to support claims about climate change impacts on extremes, but the discussion about record highs outpacing record lows is a good one and provides strong evidence for influence of global warming on regional weather. Scott Robeson Professor, Indiana University: This is a solid article that accurately describes recent record warm events in the US. A global perspective would have helped, as the US represents just 4% of the area of the Northern Hemisphere. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from the article; comments and replies are from the reviewers. 1.The US has experienced an increasing number of record highs vs. record lows over the last few decades. Such trend in statistics provides strong evidence for a warming climate. “Taken as a whole, the month-to-date in the U.S. has seen a ridiculously lopsided ratio of daily record highs to daily record lows, which is a key indicator of short-term weather variability and, over the longer term, human-caused climate change.” Andrew King Research fellow, University of Melbourne: This is an important qualification. We expect in a stationary climate that we would have some periods with more record hot temperatures than record lows and vice versa. Over an extended period of time, in a stationary climate, this ratio would average to be one. It’s because this pattern of more record hot than record cold temperatures has persisted over recent decades that allows us to link this trend to climate change. “As the planet warms in response to the buildup of greenhouse gases in the atmosphere, the ratio of high temperature records compared to low temperature records has become more skewed. If the climate weren’t warming, that long-term ratio should average out to about 1-to-1.” Ryan Sriver Associate Professor, University of Illinois: The shift towards more warm extremes suggests the underlying distributions (weather) are changing. The climatology is shifting towards higher temperatures. “While transient weather variability is playing a key role here, the widespread record warmth across the U.S. so far this year is part of a long-term trend toward more warm temperature records versus cold ones.” Scott Robeson Professor, Indiana University: The author correctly points out that it’s the superposition of persistent, extreme jet-stream fluctuations and the background of rising temperatures that is leading to more record warm extremes. Whether the extreme jet-stream fluctuations themselves are part of the changing winter climate is still unclear. Andrew King Research fellow, University of Melbourne: This paper is the first I’m aware of to highlight this effect over the US: Meehl et al (2009) Relative increase of record high maximum temperatures compared to record low minimum temperatures in the U.S., Geophysical Research Letters Ryan Sriver Associate Professor, University of Illinois: I agree that the year-to-year natural variability can contribute significantly to extreme temperatures, especially at local or regional scales. The disproportionate number of record highs versus record lows over several years-to-decades suggests that the seasonal temperature distributions (or likelihoods of experiencing a given extreme during any given season) are shifting toward warmer temperatures consistent with long-term anthropogenic global warming. How continued warming affects the tails of the distributions (beyond just shifting the location) is an interesting and open question. 2.February saw some unusual warmth in the US. “So far this month, there have been nearly 5,000 daily record highs set or tied, compared to just 42 daily record lows.” Scott Robeson Professor, Indiana University: It is very appropriate to look at this ratio of record highs versus record lows, as the climate stations themselves have different periods of records and therefore different expected rates of records (all are “long term” and have at least 30 years of data but some have much longer periods of record). But, one would still expect a one-to-one ratio of record highs to record lows in a stationary climate regime. “In Albany, New York, the high temperature of 74 degrees on Thursday was the warmest temperature on record for any day during the months of December, January and February.” Scott Robeson Professor, Indiana University: Seasonal records like this are even more impressive and much more robust as they are composed of much larger sample sizes than the individual day’s values.

https://science.feedback.org/review/worlds-coral-reefs-severely-threatened-climate-change-human-impacts-abc-story-notes/

Mostly correct

ABC News, Greg Hassall, Rebecca Latham, 2017-02-23

90 per cent of the world's coral reefs will disappear in the next 35 years due to coral bleaching induced by global warming, pollution and over-development.

Imprecise: Clarification required: It is not certain that these corals will necessarily be dead by 2050, but instead are likely to be unsustainable, i.e., susceptible to dying after heat stress events. Somewhat misleading in that it might be understood as if the reef (the platform of rock and mineral skeletons on which corals and other species live) will physically disappear, while in reality the statement should be about the death of corals.

About half of the coral that were alive in preindustrial times have already been lost, and most corals living on reefs today are likely to be unsustainable by the end of this century.

Scientists estimate 90 per cent of the world's coral reefs will disappear in the next 35 years due to coral bleaching induced by global warming, pollution and over-development.

Katrin Meissner Professor, University of New South Wales: This is a fair statement, based on several peer-reviewed studies. For example, Meissner et al. (2012)* conclude that: “Regardless of the [greenhouse gas] concentration pathway” (RCP 3PD, RCP 4.5, and RCP 8.5), “virtually every reef considered in this study (>97%) would experience severe thermal stress by year 2050.” This paper considered a range of future concentration pathways from the most aggressive “business as usual” to the most optimistic (RCP 3PD, which peaks at 440 ppm), and calculated the probability of reoccurring severe bleaching events at the locations of major coral reefs worldwide. The analysis was based on future projections simulated with a climate model and superimposed natural climate variability (El Niño Southern Oscillation). “Severe thermal stress” means that a coral reef does not have enough time to recover between two severe bleaching events. Furthermore, a high percentage of reefs will also be stressed by ocean acidification by 2050 (see figure below). When we also add local pollution, increased nutrient and sediment loading, and over-development as stress factors, we can conclude that ABC’s statement is likely an underestimation. Figure – Open ocean surface seawater aragonite saturation. Left column shows the RCP 3PD simulation (year 2030 (a), year 2050 (c), and year 2100 (e)); right column the RCP 8.5 simulation (year 2030 (b), year 2050 (d), and year 2100 (f)). Reefs in blue have a less-than-10% probability of experiencing a severe bleaching event and live in areas with annual mean open ocean seawater aragonite saturation above 3.3. Orange reefs are thermally stressed experiencing a severe bleaching event at least once every 10 years. Light blue reefs are chemically stressed (annual mean seawater aragonite saturation below 3.3), and reefs in red are both thermally and chemically stressed. Meissner et al (2012) Large-scale stress factors affecting coral reefs: open ocean sea surface temperature and surface seawater aragonite saturation over the next 400 years, Coral Reefs Ken Caldeira Senior Scientist, Carnegie Institution for Science: We have made projections* indicating that, if current CO2 emission trends continue, no coral reefs will be sustainable after about mid-century. That doesn’t mean they will all disappear at that time, but rather if they were subject to some kind of major disaster, they would be unlikely to be able to recover. The statement reads: “Scientists estimate 90 per cent of the world’s coral reefs will disappear in the next 35 years due to coral bleaching induced by global warming, pollution and over-development.” I am not familiar with every projection by every scientist, but it is not unlikely that some scientists have made such an estimate and it is possible that they could be right. It is also true that there would be scientists would would not think that that estimate was credible. The author of the article should have written: “Some scientists estimate … ” rather than “Scientists estimate … “. Assuming the scientists were correctly quoted, I would have been happier if they would have used the word “could” instead of “will” to express a sense of uncertainty. Things are bad enough. If there are greater than 10% of coral reefs hanging on in year 2052, they are likely to be unsustainable and on their way out. I don’t want to allow apologists for environmental destruction to be able to point to those reefs and claim that scientists in 2017 were being unnecessarily alarmist. Cao and Caldeira (2008) Atmospheric CO2 stabilization and ocean acidification, Geophysical Research Letters Ricke et al (2013) Risks to coral reefs from ocean carbonate chemistry changes in recent earth system model projections, Environmental Research Letters Silverman et al, (2009) Coral reefs may start dissolving when atmospheric CO2 doubles, Geophysical Research Letters Mark Eakin Scientist, Coordinator of NOAA’s Coral Reef Watch, National Oceanic and Atmospheric Administration: I rate this as accurate. While there is some variability among models and future greenhouse gas scenarios, the message from all of them is clear: we are likely to see near-annual bleaching, disease, and/or mortality on most of the world’s reefs by around mid-century. van Hooidonk et al (2016) Local-scale projections of coral reef futures and implications of the Paris Agreement, Scientific Reports van Hooidonk et al (2013) Temporary refugia for coral reefs in a warming world, Nature Climate Change Heron et al (2016) Warming Trends and Bleaching Stress of the World’s Coral Reefs 1985–2012, Scientific Reports Logan et al (2014) Incorporating adaptive responses into future projections of coral bleaching, Global Change Biology Maynard et al (2015) Projections of climate conditions that increase coral disease susceptibility and pathogen abundance and virulence, Nature Climate Change John Bruno Professor, The University of North Carolina at Chapel Hill: This statement is misleading. It should have said, ‘Unless we immediately and substantially curb greenhouse gas emissions, global coral loss will continue and most living coral will be gone by the end of the century.’ (Yet note we’ve already lost at least 50-75%, maybe even 90% of living coral.) There are plenty of dire predictions in the scientific literature on how ocean warming will impact coral reefs in coming decades. However, even the most pessimistic interpretations do not predict any reef will “disappear” in the next 35 years or even by the end of the century. Instead, what the science clearly indicates is that if we continue emitting greenhouse gases at our current rate, by mid-century tropical ocean temperatures in many regions will be high enough (1-2 C warmer than today) to cause regular (annual to semi-annual) bleaching events. But even after mass bleaching and mass coral mortality, the reef is still there. The coral skeletons that build up the reef don’t go anywhere in the near term. The best evidence for this interpretation is that it all already played out in the Caribbean (and inmany other regions). On the reefs I work on across the Caribbean, coral populations collapsed 30-40 years ago (from warming and disease) but all the reefs are physically still there. The loss of the corals is tragic and affects the functioning of the ecosystem, but still, Caribbean reefs lacking much coral can still be inhabited by a stunning diversity of fishes and invertebrates and staggering densities of animal life not seen in any other habitat on earth. They are still massively important for fisheries and tourism, despite the loss of most the coral. I suspect the writer wanted to keep things simple, but they greatly oversimplified the problem and the changes scientists expect to occur. We will likely continue to lose reef-building corals at a rate of 1-2% per year, but zero % of the world’s reefs are expected to disappear. It’s really a story of community change, rather than loss (not to downplay the importance of those changes). The science does suggest that ~ 10% of coral communities probably won’t be wiped out by warming this century. But that’s due to natural variation in warming rates and because some reefs in cooler regions will benefit from warming. https://www.sharethefacts.co/share/6fe0043b-aabf-400f-8074-8ee57b11f893

https://science.feedback.org/review/scientists-just-detected-major-change-earths-oceans-linked-warming-climate-chris-mooney-the-washington-post/

2

The Washington Post, by Chris Mooney, on 2017-02-15.

"Scientists have just detected a major change to the Earth’s oceans linked to a warming climate"

This article in The Washington Post details a new study that compiled oxygen concentration measurements in the ocean from all over the world, showing a detectable global decrease of a little more than 2% since 1960. While the study does not definitively evaluate the cause of the observed decrease, this is an expected consequence of ocean warming. According to the scientists who reviewed the article, it accurately represents research on the topic—including clear and measured descriptions of the negative impacts of oxygen trends on marine life.See all the scientists’ annotations in context This is part of a series of reviews of 2017’s most popular climate stories on social media. REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Marina Levy CNRS Senior scientist, Université Pierre et Marie Curie: The content of the article is correct. It reports on a new study in Nature showing the first observational evidence of a diminution of oxygen levels in the oceans at a global scale. This is in agreement with projections from climate models. In some regions where oxygen concentrations are already low, this can be critical for ecosystems. Lauren Simkins Assistant Professor, University of Virginia: Changes in ocean chemistry, temperature, and circulation have significant consequences for marine life and can initiate positive feedbacks to accelerate ocean and atmosphere warming. This article is refreshing in that the author presents the results and significance of global ocean oxygen loss accurately and very clearly for non-expert audiences. Soeren Thomsen Postdoctoral Research fellow, Sorbonne University: This is a very good article which includes an interview with the first author as well as comments from two other researchers (Matthew Long and Denis Gilbert) who work on oxygen. The article is very accurate and the author does not exaggerate, but tries to explain several details. Jonathan Lauderdale Postdoctoral Research Associate, MIT: This article was well substantiated and measured in its reporting of the decline in global ocean oxygen concentrations, without being hysterical about the potential for mass fish suffocations, which I have seen in previous articles on this subject. Several quotes were from scientists not involved in the research paper, which lends credibility. Shame that the headline is not entirely transparent about the content of the article. The content does support the headline, but I would still consider this clickbait. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from the article; comments and replies are from the reviewers. 1.There has been a detectable decrease in oxygen concentrations in the ocean. This trend is projected to continue as the oceans warm. “A large research synthesis, published in one of the world’s most influential scientific journals, has detected a decline in the amount of dissolved oxygen in oceans around the world — a long-predicted result of climate change that could have severe consequences for marine organisms if it continues.” William Gilly Professor of Biology, Stanford University, Hopkins Marine Station: It has been clear for at least 10 years that oxygen has been declining in the world’s oceans, both in near-surface waters and at depth, particularly in those areas with strong, natural oxygen-minimum-zones. This new study greatly extends analyses of historical data to include a significantly longer time period, a much broader global area, and to the entire water column—from the surface to 6,000 meters [depth]. This volume represents most of the inhabitable volume of the planet, and what happens there impacts all organisms, including humans, that inhabit the thin skin of terra firma. “But as that upper layer warms up, the oxygen-rich waters are less likely to mix down into cooler layers of the ocean because the warm waters are less dense and do not sink as readily.” Emmanuel M Vincent Research Scientist, University of California, Merced: Enhanced stratification of the water column is indeed one mechanism that can explain the decrease in subsurface oxygen, notably in the tropics[1]. As the upper-layer of the ocean warms faster than the deeper layers, the temperature stratification increases, with the already-warm upper layer getting warmer. This enhanced thermal stratification acts as a barrier to vertical mixing, since warmer water is less dense (like when a low density fluid (e.g. oil) tops a high density fluid (e.g. water)). This stratification can prevent oxygen coming from the surface from reaching deeper layers where it gets depleted by biological activity (respiration). As climate change proceeds, the upper-ocean layer is also expected to become fresher (less salty) in the tropics as rainfall increase, further increasing the upper-ocean stratification[2]. [1] Behrenfeld et al (2006) Climate-driven trends in contemporary ocean productivity. Nature [2] Balaguru et al (2016) Global warming-induced upper-ocean freshening and the intensification of super typhoons. Nature Communications “‘Natural variations have obscured our ability to definitively detect this signal in observations,’ Long said in an email. ‘In this study, however, Schmidtko et al. synthesize all available observations to show a global-scale decline in oxygen that conforms to the patterns we expect from human-driven climate warming. They do not make a definitive attribution statement, but the data are consistent with and strongly suggestive of human-driven warming as a root cause of the oxygen decline.’” Soeren Thomsen Postdoctoral Research fellow, Sorbonne University: It’s very good that the difficulties in detecting the signal of declining oxygen are mentioned by citing a researcher. Also the very cautious statement on the reasons are good. No unnecessary panic mongering. Lauren Simkins Assistant Professor, University of Virginia: This is supported by the relatively rapid (sub-decadal to decadal) changes in global ocean oxygen loss that are consistent with rapid changes in atmospheric greenhouse gas emissions and associated warming effects on the atmosphere and ocean, when compared to the longer-term context recorded in geological archives of past ocean variability. “Because oxygen in the global ocean is not evenly distributed, the 2 percent overall decline means there is a much larger decline in some areas of the ocean than others.” Jonathan Lauderdale Postdoctoral Research Associate, MIT: I think this is a subtle and important point to make—2% globally might not seem that much but there will be areas where the decline is more significant, such as the boundaries of Oxygen Minimum Zones, where waters could go from habitable to uninhabitable. 2. Areas of the ocean that are extremely low in oxygen significantly impact local ecosystems. The trend of decreasing oxygen concentrations is associated with increasing consequences for marine life. “Moreover, the ocean already contains so-called oxygen minimum zones, generally found in the middle depths. The great fear is that their expansion upward, into habitats where fish and other organism thrive, will reduce the available habitat for marine organisms.” William Gilly Professor of Biology, Stanford University, Hopkins Marine Station: Expansion of naturally occurring oxygen-minimum-zones, particularly the world’s largest in the eastern Pacific Ocean, is becoming more and more firmly established over a vast region at depths of several hundred meters. What’s important—and counter-intuitive—about these oxygen-minimum-zone regions is that they tend to be dynamic features of some of the most productive upper-ocean areas on Earth. The Humboldt Current system off South America supports the world’s largest single-species fishery (Peruvian anchovetta) but has water with extremely low oxygen concentration in near-shore fishing zones at depths of less than 100 meters. Any vertical (upwards) expansion of this oxygen-minimum-zone will compress the surface layer where anchovetta as well as their predators (including human fishers) operate. Increasing the density of predator and prey in a shrinking volume seldom produces a pretty result. It’s not just a matter of reduced habitat for individual species—it’s more like putting an entire highly productive ecosystem into a trash compactor. “At the end of the current paper, the researchers are blunt about the consequences of a continuing loss of oceanic oxygen. ‘Far-reaching implications for marine ecosystems and fisheries can be expected,’ they write.” William Gilly Professor of Biology, Stanford University, Hopkins Marine Station: Potential biological consequences of the trends in ocean deoxygenation documented are, if anything, understated. This is really serious business. We have done a fair job at increasing public awareness of ocean acidification, and we need to do that with deoxygenation as well. The scary thing is we know very little how these two phenomena (low pH and low oxygen) work together to impact animals that live in the ocean—from plankton to predators. When you add increasing temperature to this mix, it is clear that we have a lot to learn. Soeren Thomsen Postdoctoral Research fellow, Sorbonne University: It’s true that this is the last sentence of the paper. However, they refer to another study here: Cheung et al (2012) Shrinking of fishes exacerbates impacts of global ocean changes on marine ecosystems. Nature Climate Change. 3. The warming of the world’s oceans also has many other impacts, including sea level rise and “positive feedbacks” that can further enhance global warming. “warmer oceans have also begun to destabilize glaciers in Greenland and Antarctica” Lauren Simkins Assistant Professor, University of Virginia: This is especially true for marine-terminating glaciers, meaning that the seaward-most margin of the glacier rests on a bed below sea level and, therefore, in direct contact with the ocean. Examples are glaciers in the Amundsen Sea, Antarctica such as Pine Island and Thwaites glaciers*, currently experiencing rapid retreat that is associated with warm ocean water melting the glaciers and their floating ice shelves. Jacobs et al (2011) Stronger ocean circulation and increased melting under Pine Island Glacier ice shelf. Nature Geoscience Shepherd et al (2004) Warm ocean is eroding West Antarctic ice sheet. Geophysical Research Letters “On top of all of that, declining ocean oxygen can also worsen global warming in a feedback loop. In or near low oxygen areas of the oceans, microorganisms tend to produce nitrous oxide, a greenhouse gas, Gilbert writes.” Emmanuel M Vincent Research Scientist, University of California, Merced: Another “positive feedback loop” related to ocean warming and increased stratification is that this can reduce the ocean CO2 uptake, by preventing CO2 from being mixed down into the deep ocean layers. Matebr and Hirst (1999) Climate change feedback on the future oceanic CO2 uptake. Tellus

https://science.feedback.org/review/california-dam-crisis-says-changing-climate-noah-diffenbaugh-new-york-times/

1

The New York Times, by Noah Diffenbaugh, on 2017-02-14.

"What California’s Dam Crisis Says About the Changing Climate"

This op-ed in the New York Times written by Stanford researcher Noah Diffenbaugh discusses northern California’s Oroville Dam, where damage to a spillway recently led to a temporary evacuation. Scientists who reviewed the article found that its description of the stress that climate change exerts on water infrastructure in the American West—both flood protection and water supply management during drought—is mostly accurate. However, the article’s title, “What California’s Dam Crisis Says About the Changing Climate”, can be read to imply that climate change, rather than a structural failure, is primarily responsible for the current situation at the Oroville Dam—which is not what the content of the article suggests.REVIEWERS’ OVERALL FEEDBACK: Roger Bales Professor of Engineering, University of California, Merced: Factual & background statements do generally reflect common knowledge. Climate warming means that we do need to add resiliency to our infrastructure. The 4 recommendations of the article are on track, and consistent with the state’s Water Action Plan. Upmanu Lall Professor of Engineering, Columbia University: Misleading title—the dam crisis is primarily about the aging infrastructure and the neglect of investment in engineering and R&D as to how to plan, design, and build a new generation of water and energy infrastructure, while maintaining what we have. It tells us nothing about climate change. The article itself is more nuanced and balanced, but ends up being an organ for the climate change story, which is important, while mentioning the need for urgent investment in and action on primary infrastructure only in passing. Ben Henley Postdoctoral research fellow, University of Melbourne: This is an eloquent and thoughtful article and is based on sound science in my opinion. The author’s down-to-earth descriptions of our understanding of the physical mechanisms are well communicated. He has linked his claims to peer-reviewed science in high-ranking journals. He has carefully linked the recent events to a number of broad-brush insights for the benefit of society. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Takeaways: 1. Warm dry years followed by extremely wet years have always been part of the climate of California, but warming can worsen both extremes by increasing evaporation, which makes droughts worse as well as put more moisture into the atmosphere allowing heavier downpours. The juxtaposition of five years of hot, dry conditions followed by more rain than reservoirs can store may seem incongruous. However, this is exactly what climate scientists have predicted for California since at least the 1980s: protracted periods of warm, dry conditions punctuated by intense wet spells, with more rain and less snow, causing both drought and floods. Roger Bales Professor of Engineering, University of California, Merced: Point that “… hot, dry conditions followed by more rain than reservoirs can store ..” is not “incongruous”, but rather consistent with the climate history of California. “[…] in fact this pattern is already emerging, with the conditions that create extremely warm dry years and extremely wet years both becoming more frequent.” This statement is supported by the study hyperlinked in the text*, which identified an increase in regional atmospheric circulation patterns associated with both extremely wet and extremely dry years in California since the middle of the 20th century. Swain et al (2016) Trends in atmospheric patterns conducive to seasonal precipitation and temperature extremes in California, Science 2. Warming means that a growing fraction of precipitation falls in the form of rain rather than snow, which increases runoff. “In an old climate, … extremely warm years were less common and snowpack was more reliable … With the shift toward more rain rather than snow, and the earlier melting of the snowpack, water managers need to release water more frequently for flood control.” This statement is supported by a recent study* of the amplified warming rate experienced at high altitudes in the Sierra Nevada, which results from the loss of sunlight-reflecting snow cover. Walton et al (date) Incorporating Snow Albedo Feedback into Downscaled Temperature and Snow Cover Projections for California’s Sierra Nevada, Journal of Climate Roger Bales Professor of Engineering, University of California, Merced: It doesn’t take much warming to change snowstorms into rainstorms. With a warmer climate, we get these winter storms, which dump rain rather than snow. The “need to release water more frequently” is not necessarily true. The key needs are to upgrade the spillway, damage to which is limiting release capacity, and update the information system used to decide releases. The state is well aware of this, and public funds for investments remain limited in the current political climate.

https://science.feedback.org/review/big-melt-global-sea-ice-record-low-usa-today-doyle-rice/

1.4

USA Today, by Doyle Rice, on 2017-02-08.

"The big melt: Global sea ice at record low"

This USA Today article by Doyle Rice describes a US National Snow & Ice Data Center announcement that the combined extent of Arctic and Antarctic sea ice set a record low for January extent. The five scientists who reviewed the article concluded that it is accurate. It properly conveys the core facts about global sea ice extent and the attribution of continuing sea ice loss to human-induced warming of the climate—primarily in the Arctic, as the low sea ice extent around Antarctica this year has not yet been clearly connected to climate change.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Steffen Tietsche Senior Scientist, European Centre for Medium-Range Weather Forecasts: The article does a good job in conveying the basic facts about sea ice and how it has been changing to a reader without prior knowledge of the subject. The strong statements it makes about the recently observed sea ice extremes are correct, and backed up by appropriate numbers, figures, and expert quotations and references. Michel Tsamados Lecturer (Assistant Professor), University College London: This is a factual article and gives an accurate representation of the state of the sea ice cover in 2016/2017. One small caveat is that the author states that “sea ice is shrinking to levels not seen in thousands of years” which is a bit vague and still a topic of active research. The IPCC report has a more timid statement (maybe too cautious?). This article is based on facts, and does not attempt to over-interpret or extrapolate from these facts. References: to the sources are provided. I consider the article trustworthy. Alek Petty Postdoctoral associate, NASA Goddard Space Flight Center: The article did a pretty good job in general of discussing recent sea ice decline, relying mainly on information from the NSIDC and NASA (reliable sources). The article was sometimes a bit loose in the language used, however (as highlighted by the annotations). This was somewhat unfortunate, as it would have been a good opportunity to provide the reader with more insight into the impact of sea ice decline, and the open questions that remain (e.g. regarding how it might impact US weather). Twila Moon Research Scientist, University of Colorado, Boulder: An excellent article that does a good job of summarizing current measurements of the loss of sea ice, especially in the Arctic. The article also hits on why this change is important and that the reduction in sea ice is directly connected to man-made climate change. These are important scientific points. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : 1.Global sea ice extent is at an all time low. “There is now less sea ice on Earth than at any time on record. Ice in the Arctic and Antarctic melted to record low levels in January, scientists reported this week.” Michel Tsamados Lecturer (Assistant Professor), University College London: Focusing on sea ice extent can be dangerous as it is partly driven by short-term weather patterns, in contrast to the volume of sea ice that is now regularly monitored by European Space Agency satellite Cryosat and is more indicative of slower climatic changes. Having said that, 2016/2017 has displayed such unusual patterns in total sea ice extent that it has triggered renewed interest in the scientific community. One has to bear in mind that the seasonal developments of Arctic and Antarctic sea ice are out of phase by ~6 months. Hence, the Earth’s “total” sea ice extent is a number with limited meaning, and is not directly obvious to interpret. In addition, this number smooths out regional variations, which can be particularly pronounced in the Antarctic. Nevertheless, just like global-mean temperature or the GDP of a country, this number can be useful to have a 0th-order view on the health and state of our planet. “Using paleoclimatic data, studies suggest sea ice is shrinking to levels not seen in thousands of years.” Michel Tsamados Lecturer (Assistant Professor), University College London: The relevant assessment from the latest IPCC report(Chapter 5 Information from Paleoclimate Archives) is: “There is medium confidence from reconstructions that the current (1980–2012) summer sea ice retreat was unprecedented and sea surface temperatures in the Arctic were anomalously high in the perspective of at least the last 1450 years. Lower than late 20th century summer Arctic sea ice cover is reconstructed and simulated for the period between 8000 and 6500 years ago in response to orbital forcing.” 2.The pronounced loss of sea ice in the Arctic is largely due to human-caused climate change, but natural variability can also be considerable—especially in the Antarctic. “‘Greenhouse gases emitted through human activities and the resulting increase in global mean temperatures are the most likely underlying cause of the sea ice decline,’ the snow and ice data center said.” Observed trends in Arctic sea ice result from the superposition of forced, man-made variations and internally generated variations. While it is clear from the literature (see IPCC WG1 AR5 Chapter 10 for a review) that observed trends cannot be explained by internal variability alone, it should be remembered that internal variability can also modulate the forced trends, in a way that is complex to properly describe. In conclusion, greenhouse gases are well responsible for the observed decline, but their effect on sea ice trends may have even been amplified by internal variability. “The amount of summer sea ice in the Arctic has steadily declined over the past few decades because of man-made global warming, according to the National Oceanic and Atmospheric Administration.” Michel Tsamados Lecturer (Assistant Professor), University College London: A recent study* makes this link very tangible by attributing every loss of 3 ± 0.3 m2 of September sea-ice area to 1 metric ton of man-made CO2 emissions. Notz and Stroeve (2016) Observed Arctic sea-ice loss directly follows anthropogenic CO2 emission, Science “Sea ice thickness also substantially declined in the latter half of the 20th century, the snow and ice data center said.” Twila Moon Research Scientist, University of Colorado, Boulder: This is an important change to emphasize because sea ice thickness is also an indicator of sea ice age. While thin sea ice can reform more quickly year to year, thick sea ice requires more time. The loss of thick sea ice is perhaps even more striking than the loss of ice area. It should be added here that this is talking about Arctic sea ice. Alek Petty Postdoctoral associate, NASA Goddard Space Flight Center: Agree—and adding how we don’t know much about Antarctic sea ice thickness would have been helpful. “At the bottom of the world, sea ice is also at all-time record low levels around Antarctica, the data center said. The lack of ice in the Antarctic, where it is currently summer, is most pronounced in the Amundsen Sea, where only a few scattered patches of ice remain.” Looking at recent time-evolution of Antarctic sea ice anomalies since November 2016 is insightful to appreciate the complexity of Antarctic sea ice dynamics. In early austral spring (below) the total Antarctic sea ice extent was already anomalously low because of strong ice retreat in the Indian Sector. Three months later, the extent anomaly has persisted but is due to an unusual ice retreat in the Amundsen sector—i.e., at the exact opposite location—as the article correctly reports: This short example reveals why sea ice extent is a useful, but not sufficient diagnostic to characterize the recent sea ice variability. “Antarctic ice fluctuates wildly year to year, and the link to man-made global warming there is not clear, NASA ice expert Walt Meier said.” Michel Tsamados Lecturer (Assistant Professor), University College London: This is true for the Antarctic, while the Arctic is expected to respond more significantly to climate change—the so-called polar amplification. This is described in detail in Box 5.1 | Polar Amplification of IPCC chapter 5 Information from Paleoclimate Archives. On short time scales (~100 years) the Antarctic response differs from the Arctic and displays a delayed warming. There are several hypotheses proposed (see, for example, Ferreira et al, 2016*). Ferreira et al (2016) Antarctic Ocean and Sea Ice Response to Ozone Depletion: A Two-Time-Scale Problem, Journal of Climate 3.Sea ice loss can influence climate and weather patterns beyond just the polar regions, but some aspects of these connections are still uncertain. “[Sea ice] also helps regulate the planet’s temperature by influencing the circulation of the atmosphere and ocean. It can affect weather in the U.S.” Michel Tsamados Lecturer (Assistant Professor), University College London: Sea ice acts as an insulating blanket over the Arctic Ocean and by removing it (via our impact on the climate) we are “performing the largest experiment in oceanography”, allowing the winds and atmosphere to directly interact with the Arctic Ocean and therefore potentially waking up the “sleeping Arctic Ocean” both mechanically and thermodynamically. (See the Lunch Hour Lecture at University College London below.) Twila Moon Research Scientist, University of Colorado, Boulder: Sea ice cover is also better at reflecting energy from the sun than open ocean. This makes sea ice an important player in keeping the ocean surface from taking up additional heat. There is currently no consensus in the scientific community about the magnitude of Arctic-lower-latitudes teleconnections compared to other teleconnections (e.g. from the tropics). This statement has to be taken with caution.

https://science.feedback.org/review/daily-mail-inflates-disagreement-scientists-data-handling-make-unsupported-accusation-data-manipulation/

Unsupported

Daily Mail, David Rose, 2017-02-04

world leaders were duped into investing billions over manipulated global warming data

Unsupported: David Rose does not provide tangible evidence of “data manipulation”. The claim that the data discussed were critical to world leaders signing the Paris agreement is also not supported by evidence.

David Rose provides no evidence that global temperature data were manipulated. In reality, the data in question 1) have been verified by independent research and 2) do not significantly change the assessment of global warming relied on by policymakers.

How world leaders were duped into investing billions over manipulated global warming data… The report claimed the pause in global warming never existed, but it was based on misleading, ‘unverified’ data

Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: The “astonishing evidence” that David Rose purports to reveal in no way changes our understanding of modern warming or our best estimates of recent rates of warming. It does not in any way change the evidence that policymakers have at their disposal when deciding how to address the threats posed by climate change. If anything, there is strong independent evidence that NOAA’s new record may be the most accurate one over the last two decades, at least for the two-thirds of the world covered in ocean. Rose’s claim that NOAA’s results “can never be verified” is patently incorrect, as we just published a paper independently verifying the most important part of NOAA’s results. I recently led a team of researchers that evaluated NOAA’s updates to their ocean temperature record. In a paper* published last month in the journal Science Advances, we compared the old NOAA record and the new NOAA record to independent instrumentally homogenous records created from buoys, satellite radiometers, and Argo floats. Our results, as you can see in the chart below, show that the new NOAA record agrees quite well with all of these, while the old NOAA record shows much less warming. The new NOAA temperature record is by no means an outlier when compared to other groups producing global (land and ocean) surface temperature records. It shows less warming in recent years than records from Berkeley Earth, NASA, and Cowtan and Way, and a bit more warming than found in the Hadley Centre/CRU record. The old NOAA record, on the other hand, was on the bottom of the pack, with less warming than found by the other groups. Figure: Global land/ocean temperature records from NOAA, NASA, Berkeley Earth, Hadley/UAE, and Cowtan and Way. Note that the old (pre-Karl et al.) NOAA temperature record is only available through the end of 2014. Hausfather et al (2017) Assessing recent warming using instrumentally homogeneous sea surface temperature records, Science Advances Timothy Osborn Professor, University of East Anglia, and Director of Research, Climatic Research Unit: My overall take on the article is that it is misleading and inaccurate. The headline’s claim that the Karl et al. paper “duped” world leaders into investing billions is utterly false. Leaving aside the question of whether the Karl et al. paper is invalid (it isn’t), the improvement to global temperature records reported by Karl et al. had only a small impact* on our estimate of global warming over the last century or more. It is this warming over the last 50 to 150 years that is most relevant for assessing the influence of greenhouse gases and particularly our emissions of CO2. These long-term warming trends (hardly affected by the Karl et al. paper) demonstrate the warming induced by CO2 and other greenhouse gases and provide (part of) the scientific basis for international climate agreements, like the one agreed by world leaders in Paris in 2015. *A quote from Karl et al. (2015) supports this: “For the full period of record (1880–present) (Fig. 2), the new global analysis has essentially the same rate of warming as that of the previous analysis (0.068°C/decade and 0.065°C/decade, respectively)”. Peter Thorne Professor, Maynooth University: Would Karl et al not having appeared make any material difference to our understanding of climate change? No. We have multiple indicators of a warming world (see e.g. IPCC WG1 AR5 FAQ 2.1). Also, Karl et al. sits nicely within the range of available surface temperature estimates, which includes several independent analyses and several dynamical reanalysis products. Removing the estimate wouldn’t even modify the range of available estimates to the community. So, on several grounds it’s not as important as it’s made out to be by those wishing to discredit it. That’s not to say it wasn’t important. Just that whether it existed or not wouldn’t make a difference to the biggest picture. Victor Venema Scientist, University of Bonn, Germany: Since the 19th century we have seen about 1 °C (1.8 °F) of warming. The adjustments of Karl and colleagues (2015) are only of a few hundredths of a degree Celsius and thus do not appreciably change the scientific estimates of the climate sensitivity. The largest adjustment is actually making past sea surface temperatures warmer because old bucket measurements have a known cool bias (which actually reduces the magnitude of the warming trend). That adjustment is important for the assessment of climate sensitivity using only instrumental data. In the figure below, the thick black line shows the new assessment (ERSST.v4) and the thin red line the previously estimated global temperature signal (ERSST.v3). Differences are mostly less than 0.05°C, both warmer and cooler. The [exaggeration] is the minute change at the right end of the curves. Source: Karl et al. (2015)

https://science.feedback.org/review/global-surface-temperatures-increasing-according-climate-projections-contrary-wall-street-journal-claim/

Misleading

The Wall Street Journal, Wall Street Journal editorial, 2017-01-19

the warming is not nearly as great as the climate change computer models have predicted.

Fails to grasp significance of observation: This claim is used to support an argument that climate models failed to forecast global surface temperature warming, but cherry-picks a period of time too short to provide a meaningful comparison.

Global surface temperatures are increasing consistent with the long-term trend projected by climate models.

the warming is not nearly as great as the climate change computer models have predicted. […]U.N. Intergovernmental Panel on Climate Change simulations forecast surface temperatures to increase on average 0.2 degrees Celsius per decade in the early 21st century. The warming over the first 15 years was closer to 0.05 degrees Celsius.

Christopher Merchant Professor, University of Reading and UK National Centre for Earth Observation: Although climate modellers tend to quote the trend to warmer temperatures in units of “degrees per decade”, it is a misunderstanding to interpret that to mean that they expect every decade to have that trend. This is why in the quoted statement, the forecast is for increases to be “on average” 0.2 °C. Just as weather fluctuates from day to day, there are fluctuations between years and decades, too. Piers Forster Professor, University of Leeds: The high emissions scenario (RCP8.5) model simulations did show around 0.2 °C warming per decade. But the IPCC report (Chapter 11, WG1, AR5, Fig 11.25) never relied on just these runs to make its prediction. It relied on multiple lines of evidence. Its temperature prediction was in fact around 0.05 to 0.15 C per decade. The statement “the warming over the first 15 years is 0.05 °C per decade” is not correct. (This was probably meant to be degrees per decade from an old version of the HadCRUT dataset with limited coverage on the Arctic). The latest analysis and synthesis of the different records published in Science in January* constrains sea-surface temperatures trends over the last 19 years to between 0.07 and 0.12 °C per decade. Global temperatures have been rising slightly faster than this due to land surface warming more. Hausfather et al (2017) Assessing recent warming using instrumentally homogeneous sea surface temperature records, Science Advances Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: Since the start of the 21st century, climate models predict 0.2 °C per decade surface warming. Observed surface warming over that same period has been 0.2 °C (NASA), 0.19 °C (NOAA) 0.18 °C (Berkeley/ Cowtan and Way), and 0.16 °C (Hadley). All of these are statistically indifferentiable from model projections over this period. In general, recent temperatures have been pretty close to the multi-model mean: Model comparisons with satellite data are more difficult as satellites don’t measure the Earth’s surface temperature. Some satellite records (RSSv4, UAHv5.6) are in reasonable agreement with model projections for tropospheric temperatures between 2000 and present, while others (UAHv6 beta, RSSv3) are notably cooler. Shaun Lovejoy Professor, McGill University: The figure below from Lovejoy (2015)* gives some details, but the basic claim of 0.2 °C too high is essentially correct. However, as the figure shows, the temperature was accurately forecast (actually hindcast) to within 0.05 °C by using a stochastic (not General Circulation Model) modelling approach. The stochastic approach worked well because the so-called pause (since 1998) was actually simply a return to the long-term (anthropogenically forced) trend that followed the massive pre-pause warming from 1992 to1998. The key point is that the fact that General Circulation Model’s tended to over-forecast the warming is a model and/or data problem (there are many different explanations in the literature), but this in no way alters the fact that the temperatures are almost exactly varying about the long term anthropogenic trend as expected. Lovejoy (2015) Using scaling for macroweather forecasting including the pause, Geophysical Research Letters

https://science.feedback.org/review/scientists-officially-declare-2016-hottest-year-record-chris-mooney-the-washington-post/

1.9

The Washington Post, by Chris Mooney, on 2017-01-18.

"U.S. scientists officially declare 2016 the hottest year on record. That makes three in a row."

On January 18th, NOAA and NASA released their annual assessment of the state of the global climate, including the fact that 2016 was the warmest year on record. The Washington Post article discusses the degree of confidence in this result, the factors contributing to the new record, and some of the ways in which different regions were impacted by this warmth. Scientists found this article accurate and insightful in that it provides the context necessary to understand the significance of this new temperature record. It correctly notes that the record can be tied to human influence on the climate, even though El Niño played a role in further boosting the global temperature.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. James Screen Associate Professor, University of Exeter: The article accurately conveys the US agencies’ declaration of 2016 as the hottest year on record. It provides some good background material on why the agencies’ numbers differ slightly (treatment of the Arctic) and the contributing roles of El Niño and man-made global warming. Mark Eakin Scientist, Coordinator of NOAA’s Coral Reef Watch, National Oceanic and Atmospheric Administration: The article accurately depicted the new data released by NOAA and NASA and used appropriate and valid scientific quotes to place the news in context. It also went beyond the simple temperature analysis to discuss some of the significant impacts felt in various parts of the world this year. Daniel Swain Climate Scientist, University of California, Los Angeles: This piece accurately describes the facts and broader context of record-breaking global warmth in 2016. Christopher Colose Research Scientist, SciSpace LLC, NASA Goddard Institute for Space Studies: This is a useful summary of the key points outlined by NASA and NOAA, discussing the proximate causes of the 2016 warmth compared to surrounding years (mostly El Niño), and also that there is a sharp upward trend upon which natural variability is superimposed. Andrew King Research fellow, University of Melbourne: This article accurately describes why 2016 was record-breaking and makes insightful comments about the causes for differences between datasets. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: An excellent overview of 2016 temperatures, with some detailed exploration of the differences between NOAA and NASA records. The only thing I might have added is some discussion of satellite tropospheric temperatures. James Renwick Professor, Victoria University of Wellington: An excellent summary, drawing on several leaders in the field of climate science. Julien Emile-Geay Assistant Professor, University of Southern California: Chris Mooney reads what scientists say and reports on it without hyperbole or distortion. Thermometers and sea ice have no political agenda, and this article does a good job of summarizing the most recent evidence and scientific analyses based on them. Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: Balanced descriptions of different datasets, and used explanations from scientists in appropriate places very well. Victor Venema Scientist, University of Bonn, Germany: Great article, accurate in detail (the reasons for fluctuations and for differences between datasets) while keeping sight of the big picture (the long-term trend due to man-made global warming). Aimée Slangen Researcher, Royal Netherlands Institute for Sea Research (NIOZ): The article provides a good evaluation of the record year 2016 by including data from different datasets and agencies. It not only discusses the global mean temperature record, but also notable events such as the Arctic sea ice low. All of this combined, it shows that the big picture is clearer than ever. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from the article; comments and replies are from the reviewers. 1.2016 was the warmest year on record in all agencies’ datasets. The small differences between datasets mostly relate to their methods of accounting for warming in the Arctic, where measurements are limited. “NASA concurred with NOAA, also declaring 2016 the warmest year on record in its own data set that tracks the temperatures at the surface of the planet’s land and oceans, and expressing ‘greater than 95 percent certainty’ in that conclusion. (In contrast, NOAA gave a 62 percent confidence in the broken record.)” Victor Venema Scientist, University of Bonn, Germany: The difference between NOAA and NASA-GISS is because of the way the Arctic—where much of the warming was in 2016, but where we do not have many measurements—is treated. NOAA excludes much of the Arctic, which gives it a cool bias in 2016, which is accounted for by a larger uncertainty. NOAA. The gray areas are where NOAA’s methods do not have enough observations to compute the temperature. Not computing a temperature is similar to assuming these regions warm like the global average, but the Arctic warmed more. GISTEMP of NASA-GISS uses other mathematical methods and does compute temperatures for the Arctic, which results in a more accurate global average. “Two other global agencies, the Japan Meteorological Agency and Britain’s Hadley Center, also track global temperatures.” Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: Other groups, including Berkeley Earth and Cowtan and Way, also agree that 2016 was a record warm year. It’s also a record warm year when you look at raw ocean and land data with no corrections or adjustments. “But the differences between NOAA and NASA aren’t that significant, Schmidt further argued, in the context of the bigger picture. ‘Getting hung up on the exact nature of the records is interesting, and there’s lots of technical work that can be done there, but the main take-home response there is that the trends we’ve been seeing since the 1970s are continuing and have not paused in any way,’ he said.” Daniel Swain Climate Scientist, University of California, Los Angeles: This section accurately portrays the overall context of the 2016 record, and the fact that the modest differences between datasets do not change the “big picture” conclusion that the Earth is warming and that 2016 was an extraordinary year even in that context. 2.This record is mostly attributable to human-induced global warming, but the El Niño event in 2016 also contributed. “[Jonathan Overpeck:] ‘No doubt about it anymore — humans, mainly by burning fossil fuels, are cooking the planet,’ Overpeck said.” Aimée Slangen Researcher, Royal Netherlands Institute for Sea Research (NIOZ): There is indeed a vast body of literature on ”detection and attribution” showing how the increase of greenhouse gases can be linked to changes in the climate system. Already in the most recent IPCC report this was shown for quantities such as surface temperature, ocean temperature, global mean sea level rise, Arctic sea ice loss, and glacier and ice sheet mass loss. Publications since have confirmed these findings. “[Jonathan Overpeck:] ‘it is caused by humans’” Margot Saher Lecturer, Bangor University, Wales, UK: The usual method of prying apart the various factors responsible for temperature changes is by modelling; we know the input of the Sun, we know the composition of the atmosphere, etc. If you have a climate model that, with these parameters, can reproduce the climate of the past, you can be fairly sure that, even being by definition a simplification, it gets the physics right. You can then use the model to calculate what the influence of each individual parameter was*. You can even switch parameters on and off to see what happens. These models can then also be used for climate predictions under various assumptions on, say, greenhouse gas emissions. Huber and Knutti (2012) Anthropogenic and natural warming inferred from changes in Earth’s energy balance, Nature Geoscience “‘This El Niño might have contributed about a quarter or a third’ of the record in 2016, said Deke Arndt, chief of the global monitoring branch at NOAA’s National Centers for Environmental Information, on a press call Wednesday.” Christopher Colose Research Scientist, SciSpace LLC, NASA Goddard Institute for Space Studies: I find this part confusing. The “percentage of the anomaly” caused by El Niño depends of course on the anomaly, which depends on the baseline. So it’s not really a useful number. El Niño caused a much larger fraction if you only look at a very recent baseline (e.g. just compare to 2014-15). A more straightforward number is the 2016 anomaly relative to what it would have been if ENSO were in a neutral phase. I calculated this to be ~0.13 C (0.23 F). Victor Venema Scientist, University of Bonn, Germany: I agree with Chris Colose. If you mention a fraction (a quarter or a third) you need to mention relative to what. The total warming since 1900 is about 1°C. The influence of El Nino on the 2016 temperature was small compared to that. Source “The particular signature of warming in 2016 was also revealing in another way, Overpeck said, noting that the stratosphere… saw record cold temperatures last year” Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: The troposphere (the lower part of the atmosphere) has also been rapidly warming. A newly updated record from Remote Sensing Systems using data from NASA satellites shows more warming in the troposphere than on the surface since 1979 (when satellite records began): “[Gavin Schmidt:] ‘We don’t expect record years every year, but the ongoing long-term warming trend is clear.’” Andrew King Research fellow, University of Melbourne: This is a really important point, especially as 2017 is likely to not break the 2016 record. We expect year-to-year variability, so we may not break the 2016 record for a few years, but the overall trend is upwards. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: Scientists like NASA’s Gavin Schmidt are also predicting slightly cooler 2017 temperatures as the El Niño fades, with 2017 projected to be somewhere between the 2nd and 5th warmest year on record. That said, we wouldn’t expect every single year to be a new record, and a slightly cooler 2017 is in no way inconsistent with the long term warming trend. 3.The consequences of ongoing climate change include impacts on coral reefs, Arctic sea ice coverage, and wildfires, among other things. “Last year’s warmth was manifested across the planet, from the warm tropical ocean waters off the coast of northeastern Australia, where the Great Barrier Reef experienced its worst coral bleaching event on record and large scale coral death, to the Arctic, where sea ice hit regular monthly record lows and overall temperatures were also the warmest on record, at least from January through September 2016.” Daniel Swain Climate Scientist, University of California, Los Angeles: This section accurately describes major 2016 events that occurred in the Earth system, and which most likely would not have occurred without global warming. Mark Eakin Scientist, Coordinator of NOAA’s Coral Reef Watch, National Oceanic and Atmospheric Administration: The article overlooks the fact that not only was the bleaching on the northern Great Barrier Reef the worst on record, so was the bleaching in many areas around the world. In fact, the global coral bleaching event that is still underway is the longest, most widespread, and perhaps most damaging event on record. “Extreme high temperatures were seen from India — where the city of Phalodi recorded temperatures of 51 degrees Celsius (123.8 Fahrenheit) in May, a new national record — to Iran, where a temperature of 53 degrees Celsius (127.4 F) was recorded in Delhoran on July 22.” Andrew King Research fellow, University of Melbourne: No direct link with climate change has been drawn by the article here and this is good. For these daily heat records, attribution to human-caused climate change is a lot harder than for extremes that occur on longer or larger scales. Indeed, in parts of India, the increase in aerosols due to pollution has counteracted the warming from greenhouse gas emissions so that there is virtually no trend in extreme high temperatures.

https://science.feedback.org/review/ocean-acidification-yet-another-wobbly-pillar-climate-alarmism-james-delingpole-the-spectator/

-2

The Spectator, by James Delingpole, on 2016-04-30.

"Ocean acidification: yet another wobbly pillar climate alarmism"

Research shows that the pH of the ocean is currently decreasing due to human emissions of CO2 and that this already has negative consequences for marine ecosystems—and continued emissions is expected to have further negative consequences. The article in The Spectator claims the contrary. The scientists who have analyzed the article show that it contains significant inaccuracies, notably for its core assumptions, and misrepresents scientific studies and scientists it cites to make its point. Reviewers also note that the article knocks down strawman arguments that do not represent the state of scientific knowledge (scientists do not claim the ocean will become a “giant acid bath”) and uses derogatory language by referring to ocean acidification researchers as “alarmists”. Note: This article, published in April 2016, is being assessed now because of renewed interest in the media following IPSO’s ruling (IPSO is the UK Independent Press Standards Organisation).See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Howard Browman Principal Research Scientist, Norwegian Institute of Marine Research: As Phil Williamson has carefully documented, it is a story built upon selective back-grounding, based upon dubious sources, and presented in support of the author’s own predetermined storyline and conclusion. Adam Subhas PhD candidate, Caltech: This article bases its arguments on non-peer-reviewed publications and a study which uses poorly calibrated historical data. The article also oversimplifies the science behind ocean acidification in an attempt to trivialize well-understood chemical principles that predict how CO2 dissolving into the ocean will affect ocean pH. Ken Caldeira Senior Scientist, Carnegie Institution for Science: The chemistry of ocean acidification is well understood. Negative biological consequences have been documented for many marine organisms in a diverse set of carefully controlled experiments. I was involved in an experiment in Australia’s Great Barrier Reef where we added an ‘antacid’ to a plume of seawater, bringing seawater chemistry closer to what it was several hundred years ago. We let that water flow over a patch of reef and measured an increase in the growth rate of the reef. This showed that the increase in acidity caused by our CO2 emissions is already slowing reef growth, harming the reef. Our measurements come out of sophisticated and carefully calibrated scientific instruments. They measure what is out there in the physical world, without any reference to our political views or our degree of alarm. Our measurements are not a matter of opinion. Jean-Pierre Gattuso Research Professor, CNRS, Université Pierre et Marie Curie and IDDRI: This is an appalling article which distorts the scientific evidence by disqualifying thousands of peer-reviewed articles and highlighting only two un-peer-reviewed publications from non-expert authors. Tullio Rossi Marine biologist, University of Adelaide: This is by far the most inaccurate article on ocean acidification I have ever seen. It is an explosive mix of false statements, cherry picking, and plain anti-science feelings. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from the article; comments and replies are from the reviewers. 1. The acidity of seawater (hydrogen ion concentration) has increased by about 30% over the industrial era due to the human-caused increase of atmospheric CO2. “In 2004, two NOAA scientists, Richard Feely and Christopher Sabine, produced a chart showing a strong correlation between rising atmospheric CO2 levels and falling oceanic pH levels. But then, just over a year ago, Mike Wallace, a hydrologist with 30 years’ experience, noticed while researching his PhD that they had omitted some key information[…] his results were surprising: there has been no reduction in oceanic pH levels in the last -century.” Tullio Rossi Marine biologist, University of Adelaide: This is plain wrong. Oceanic pH levels decreased by 0.1 units compared to pre-industrial levels. This corresponds to a 30% increase in acidity. For a primer on pH, see this NOAA explainer. Peer-reviewed references: Doney et al (2009) Ocean acidification: the other CO2 problem, Annual Review of Marine Science Raven et al (2005) Ocean acidification due to increasing atmospheric carbon dioxide, The Royal Society Ken Caldeira Senior Scientist, Carnegie Institution for Science: This statement just flies in both the face of observational facts and a basic understanding of chemistry. I would love to hear a cogent explanation of how atmospheric CO2 levels could rise over the course of a century without producing a decrease in ocean pH. Observations near Hawaii and several other open ocean environments show clear decreasing trends in ocean pH. See, for example this report from the European Environment Agency. It is one thing to challenge future projections, but rejecting well-established scientific facts is another thing entirely. Figure: Decline in pH measured at the Aloha station as part of the Hawaii Ocean time-series. Source Richard Feely Senior Scientist, NOAA's Pacific Marine Environmental Laboratory: Michael Wallace contacted Chris Sabine and myself several years ago and asked how to get access to historical pH measurements in the oceans so he could determine long-term trends of global ocean pH for himself. We directed him to both modern (as published in Feely et al., 2008) and historical pH measurements archived at the NOAA National Centers for Environmental Information. We cautioned him that the earlier data sets prior to 1989 had significant issues with data quality as described in the document that went along with the data set obtained from NCEI. Mr. Wallace went on to perform his analysis of the historical data without regard for the oceanographic community’s concerns about the data quality or for the proper methodology to perform this kind of analysis. He chose to publish his results within the context of an interview written by Marita Noon in the Farmington Daily Times. We responded by correcting the record by formally restating our concerns about Mr. Wallace’s incorrect use of the historical data on our website. In short, Wallace’s chart does not show any kind of useful trend in global ocean pH because the data he used, and the way he used them, were not appropriate for this kind of analysis. In the first place, the pH measurements prior to 1989 were not reliable enough to detect small pH changes over that period. In addition, companion meta data on sensor calibration, pH scales, and temperature corrections were not available. Finally, the data were so limited that no meaningful global averages could be determined. The article by Mr. Delingpole in The Spectator failed to address these important issues, as Philip Williamson correctly points out in his response to the article. “Ocean acidification is the terrifying threat whereby all that man-made CO2 we’ve been pumping into the atmosphere may react with the sea to form a sort of giant acid bath.” Jean-Pierre Gattuso Research Professor, CNRS, Université Pierre et Marie Curie and IDDRI: That is incorrect. No peer-reviewed article claim that the ocean will become acid (pH < 7). “‘Acid’ was chosen, Moore believes, because it has ‘strong negative connotations for most people’.” Tullio Rossi Marine biologist, University of Adelaide: The terms acidification was not chosen for its negative connotation but rather because it defines the direction of change. Here is a simple example: when you describe the cooling of your coffee what term do you use? Cooling or un-warming? If the temperature is going down we say it is cooling. If the temperature is going up we say it is warming. The same applies to acidity. When the pH of something goes down we say that it is acidifying. That simple. “so more correctly it should be stated that the seas are becoming slightly less alkaline.” Adam Subhas PhD candidate, Caltech: This is actually not correct. Invasion of CO2 into the ocean does not change its alkalinity at all. By adding carbonic acid, and keeping alkalinity constant (defined as either the difference between dissolved cations and anions, or the excess of acid-base species at the CO2 equivalence point), the pH decreases. “seawater has a large buffering capacity which prevents dramatic shifts in pH;” Adam Subhas PhD candidate, Caltech: This is true; however, the amount of CO2 emitted by humans is also massive, a large portion of which has already been absorbed by the oceans. Since pH is relatively insensitive to changes in CO2, it is often not the right parameter to look at in the whole system. For example, over the range of pH values which the author states are found in natural seawater, the surface pCO2 changes from 180 ppm (pH 8.3) to 1500 ppm (pH 7.5). Thus, a mean change in ocean pH of 0.3 pH units represents almost a tripling of seawater pCO2. 2. Decreasing ocean pH is documented to pose significant risks to marine ecosystems, though the magnitude of the impacts depends on specific species. “[…]The impact on calcification, metabolism, growth, fertility and survival of calcifying marine species when pH is lowered up to 0.3 units […] is beneficial, not damaging. Marine life has nothing whatsoever to fear from ocean acidification.” Ken Caldeira Senior Scientist, Carnegie Institution for Science: There is much evidence available to falsify this statement. Many experiments have shown substantial negative biological responses at these levels of pH change. Of course, some organisms are relatively unaffected by these levels. An older review that is available here without a paywall: Langdon (2002) Review of experimental evidence for effects of CO2 on calcification of reef builders. In Proc. 9th Int. Coral Reef Sym. “Then it will destroy all the species that depend on it — causing an almighty mass extinction which will wipe out the fishing industry and turn our oceans into a barren zone of death.” Jean-Pierre Gattuso Research Professor, CNRS, Université Pierre et Marie Curie and IDDRI: That is not a truthful summary of the scientific literature. Check, for example, the meta-analysis of Kroeker et al. (2013) who describe processes and organisms that do not seem to be affected by ocean acidification. Kroeker et al. (2013) Impacts of ocean acidification on marine organisms: quantifying sensitivities and interaction with warming. Global Change Biology. “a killer analysis conducted by Craig Idso of all the studies which have been done on the effects of reduced pH levels on marine life.” Jean-Pierre Gattuso Research Professor, CNRS, Université Pierre et Marie Curie and IDDRI: This publication is not peer-reviewed, cherry-picks articles and does not involve proper statistical testing. It does not, therefore, qualify as a “killer analysis”! The comprehensive metanalysis that was performed by Kroeker et al. (2013) revealed decreased survival, calcification, growth, development and abundance in response to acidification when the broad range of marine organisms is pooled together. However, the magnitude of these responses varies among taxonomic groups. Kroeker et al (2013) Impacts of ocean acidification on marine organisms: quantifying sensitivities and interaction with warming. Global Change Biology. Richard Feely Senior Scientist, NOAA's Pacific Marine Environmental Laboratory: The Idso meta-analysis described by Delingpole was never published. It does not take into account the proper method of proportional scaling analysis. It does not demonstrate how negative effects will impact ecosystem services and food-web processes that can have an effect on economically important fish and shellfish. It does not address the impacts we are already seeing on important fish food, such as pteropods (see Bednarsek et al., 2012, 2014; Feely et al., 2016). There are several highly credible published meta-analysis studies (Kroeker et al. ,2013; Wittman & Pörtner, 2013; and Busch and McElhany, 2016) that have told a much different story than Idso’s unpublished work. Delingpole failed to even mention these other studies, which show very significant impacts on several marine taxa. In summary, Delingpole’s article demonstrates a complete lack of appreciation of scientific literature on this topic and the proper choice of scientific methods for data analysis and synthesis that leads to a more accurate understanding of the present-day and future impacts of ocean acidification. Bednaršek et al (2012) Extensive dissolution of live pteropods in the Southern Ocean,Nature Geoscience Bednaršek et al (2014) Limacina helicina shell dissolution as an indicator of declining habitat,Proc. of the Royal Society B Feely et al (2016) Chemical and biological impacts of ocean acidification along the west coast of North America,Estuarine, Coastal and Shelf Science “First, marine species that calcify have survived through millions of years when CO2 was at much higher levels; second, they are more than capable of adapting — even in the short term — to environmental change” Ken Caldeira Senior Scientist, Carnegie Institution for Science: Many marine organisms respond to changes in calcium carbonate mineral saturation states. These depend not only on pH, but also on factors including amounts of carbon and calcium in the ocean. One of the most important factors is ocean alkalinity, which varies on time scale of many thousands of years. In the geologic past, when atmospheric CO2 was high, ocean alkalinity was also high, and so carbonate mineral saturation states could remain high. Unfortunately, on the timescale of centuries or decades, changes come too fast for the ocean’s natural processes to buffer ocean carbonate mineral saturation states. Directly comparing effects of high CO2 levels that developed in the geologic past over many millions of years with high CO2 levels developing today over decades and centuries shows a fundamental lack of understanding of well-established global geochemical cycles. This open access article explains some of the relevant chemistry: Cao et al (2016) Simulated effect of deep-sea sedimentation and terrestrial weathering on projections of ocean acidification,Journal of Geophysical Research Oceans Jean-Pierre Gattuso Research Professor, CNRS, Université Pierre et Marie Curie and IDDRI: Some calcifying species were indeed abundant in the Cretaceous, a time at which the atmospheric CO2 concentration was high. However, seawater alkalinity was also high due to intense weathering on land. Hence, the concentration of carbonate ions (CO3, which controls calcification) was elevated. That compensation does not happen today and will not happen in the near future because total alkalinity does not change significantly on time scales of centuries. There is ample evidence in the literature for that. Some fast-growing species are indeed able to develop some level of adaptation after several hundreds of generation. Overall, there is evidence that all past episodes of ocean warming, acidification and deoxygenation have led to mass extinctions. Furthermore, there is no calcifier close to CO2 vents, suggesting that adaptation has limited capabilities. 3.The article contains other inaccuracies and misrepresentations of its sources. “if oceans do become warmer due to ‘climate change’, the effect will be for them to ‘outgas’ CO2, not absorb more of it” Jean-Pierre Gattuso Research Professor, CNRS, Université Pierre et Marie Curie and IDDRI: Incorrect: The effect of warming is completely overwhelmed by the effect of increased atmospheric CO2. Hence, the ocean will continue to absorb massive amounts of CO2 in the future, despite ocean warming. “[ocean acidification was ] First referenced in a peer-reviewed study in Nature in 2003” Jean-Pierre Gattuso Research Professor, CNRS, Université Pierre et Marie Curie and IDDRI: The expression “ocean acidification” was actually introduced in 2001 by Broecker and Clark*. But the chemical processes involved have been know for a very long time at least the 1950s) and the impact of low pH (elevated acidity) on marine organisms since the early 1900s. The earliest experiments even predate the definition of pH by Sørensen in 1909. Broecker & Clark (2001) A dramatic Atlantic dissolution event at the onset of the last glaciation, Geochemistry Geophysics Geosystems “Howard Browman, a marine scientist for 35 years, has published a review in the ICES Journal of Marine Science of all the papers published on the subject. His verdict could hardly be more damning. The methodology used by the studies was often flawed; contrary studies suggesting that ocean acidification wasn’t a threat had sometimes had difficulty finding a publisher. There was, he said, an ‘inherent bias’ in scientific journals which predisposed them to publish ‘doom and gloom stories’.” Howard Browman Principal Research Scientist, Norwegian Institute of Marine Research: The following decomposition of this excerpt from Mr. Delingpole’s article in The Spectator identifies inaccuracies in his reporting that lead to misrepresentation of the content and intent of my article. Importantly, Mr. Delingpole never contacted me to verify that his reporting on my article was accurate. Nor was I contacted by the UK’s Independent Press Standards Organisation during their investigation of the accuracy of Mr. Delingpole’s article in The Spectator. “Howard Browman, a marine scientist for 35 years, has published a review in the ICES Journal of Marine Science of all the papers published on the subject.” Howard Browman Principal Research Scientist, Norwegian Institute of Marine Research: The article that Mr. Delingpole is referring to is not “a review”, but an introduction to a special theme issue on the topic of ocean acidification[…] The introduction does not review all of the nearly 4000 articles on the subject. Rather, it presents an overview of the sub-set of research dealing with biological/ecological effects of ocean acidification. “His verdict could hardly be more damning. Howard Browman Principal Research Scientist, Norwegian Institute of Marine Research: On p. 530 of the introduction, I state: “Although I call for a more sceptical scrutiny and balanced interpretation of the body of research on OA [Ocean Acidification], it must be emphasized that OA is happening and it will have effects on some marine organisms and ecosystem processes.” This is hardly a verdict that “…could hardly be more damning.” “The methodology used by the studies was often flawed” Howard Browman Principal Research Scientist, Norwegian Institute of Marine Research: My introduction does not present a quantitative assessment of the frequency of occurrence of methodological flaws in the ocean acidification literature. “There was, he said, an ‘inherent bias’ in scientific journals which predisposed them to publish ‘doom and gloom stories’.” Howard Browman Principal Research Scientist, Norwegian Institute of Marine Research: The words “inherent bias” do not appear in my article. Rather, I refer to “publication bias”. In research, an “inherent bias” is one which is inextricably tied to the core nature of the phenomenon being studied and cannot, therefore, be eliminated by increasing the sample size or choosing a different estimator. “Publication bias”, on the other hand, refers to the general (across all of science) phenomenon by which studies presenting positive results – supporting the hypothesis being tested – are more likely to be published than those reporting negative results. This sometimes creates a situation where published studies may be systematically different from unpublished studies – for example, studies showing an impact of ocean acidification might be published more easily and in higher profile journals than studies showing no impact. However, I only allude to this possibility in the introduction; I do not asses it quantitatively (something that would, in fact, be very difficult to do). Finally, the words “doom and gloom” do not appear in my introduction.

https://science.feedback.org/review/oceans-currently-acidifying-claims-contrary-contradict-observations/

Inaccurate

The Spectator, James Delingpole, Mike Wallace, 2016-04-30

there has been no reduction in oceanic pH levels in the last century

Factually wrong: This statement is contradicted by available evidence. Inadequate support: The basis for the claim is a non-peer-reviewed paper that has been shown to have serious flaws.

The acidity of the upper ocean has increased by about 30% (meaning its pH has dropped about 0.1 units) over the past century due to human emissions of CO2.

there has been no reduction in oceanic pH levels in the last century

Tullio Rossi Marine biologist, University of Adelaide: This is plain wrong. Oceanic pH levels decreased by 0.1 units compared to pre-industrial levels. This corresponds to a 30% increase in acidity. For a primer on pH, see this NOAA explainer. Peer-reviewed references: Doney et al (2009) Ocean acidification: the other CO2 problem, Annual Review: of Marine Science Raven et al (2005) Ocean acidification due to increasing atmospheric carbon dioxide, The Royal Society Ken Caldeira Senior Scientist, Carnegie Institution for Science: This statement just flies in both the face of observational facts and a basic understanding of chemistry. I would love to hear a cogent explanation of how atmospheric CO2 levels could rise over the course of a century without producing a decrease in ocean pH. Observations near Hawaii and several other open ocean environments show clear decreasing trends in ocean pH. See, for example this report from the European Environment Agency. It is one thing to challenge future projections, but rejecting well-established scientific facts is another thing entirely. Figure: Decline in pH measured at the Aloha station as part of the Hawaii Ocean time-series. Source Richard Feely Senior Scientist, NOAA's Pacific Marine Environmental Laboratory: Michael Wallace contacted Chris Sabine and myself several years ago and asked how to get access to historical pH measurements in the oceans so he could determine long-term trends of global ocean pH for himself. We directed him to both modern (as published in Feely et al., 2008) and historical pH measurements archived at the NOAA National Centers for Environmental Information. We cautioned him that the earlier data sets prior to 1989 had significant issues with data quality as described in the document that went along with the data set obtained from NCEI. Mr. Wallace went on to perform his analysis of the historical data without regard for the oceanographic community’s concerns about the data quality or for the proper methodology to perform this kind of analysis. He chose to publish his results within the context of an interview written by Marita Noon in the Farmington Daily Times. We responded by correcting the record by formally restating our concerns about Mr. Wallace’s incorrect use of the historical data on our website. In short, Wallace’s chart does not show any kind of useful trend in global ocean pH because the data he used, and the way he used them, were not appropriate for this kind of analysis. In the first place, the pH measurements prior to 1989 were not reliable enough to detect small pH changes over that period. In addition, companion meta data on sensor calibration, pH scales, and temperature corrections were not available. Finally, the data were so limited that no meaningful global averages could be determined. The article by Mr. Delingpole in The Spectator failed to address these important issues, as Philip Williamson correctly points out in his response to the article. CORRECTION (28 Oct. 2018): The takeaway has been updated to clarify that thehydrogen ion concentration (acidity) of the upper ocean has changed by 30%, not the pH (that measures this hydrogen ion concentration on a logarithmic scale).

https://science.feedback.org/review/arctic-ice-melt-already-affecting-weather-patterns-live-right-now-damian-carrington-the-guardian/

0.6

The Guardian, by Damian Carrington, on 2016-12-19.

"Arctic ice melt 'already affecting weather patterns where you live right now'"

This article in The Guardian discusses the influence of Arctic warming on mid-latitude weather patterns. The Arctic is warming faster than the global average, and the possibility that this warming is driving a change in the behavior of the jet stream—and the mid-latitude weather that results—has seen lots of coverage in the past few years. While the article includes interviews with a number of scientists doing research on these patterns, the scientists who reviewed it explained that the conclusions expressed aren’t completely representative of current scientific knowledge: There remains real uncertainty about the link between Arctic warming and certain mid-latitude weather patterns, which the article does not make entirely clear to the reader.See all the scientists’ annotations in contextGUEST COMMENTS: James Screen Associate Professor, University of Exeter: The article nicely introduces some of the emerging science linking Arctic climate change to extreme weather at lower latitudes. There are no major inaccuracies and the author has sought expert comment from several prominent scientists. However, the article fails to fully capture the large uncertainty about how Arctic warming may influence weather in places further south and how big this effect might be. For example, the article draws heavily on a scientific hypothesis that Arctic warming causes a more meandering jet stream and slower moving weather systems (e.g. blocking). This is a credible hypothesis supported by a few peer-reviewed publications (most prominently by one of the scientists interviewed), but there are other papers that have failed to identify such a link, or argued against one. In short, there is no scientific consensus on whether or not Arctic warming causes larger jet stream wiggles or more persistent weather. The jury is still out. Whilst some of the scientist’s quotes do hint at unknowns and ongoing scientific debate, the overall tone of the article gives the impression the science on this topic is more settled than it actually is. Stephen Vavrus Senior Scientist, University of Wisconsin-Madison: I think the writer basically captured the essence of the scientific information provided to him, although some simplifications make the state of the knowledge sound more sweeping than the consensus view in the community. There are skeptical voices in the community whose views differ from those presented in this article. A more complete story could have included them to provide an alternative perspective on the role of a changing Arctic.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Daniel Swain Climate Scientist, University of California, Los Angeles: The author has sought out and quoted relevant experts in the field, and presents specific factual information that is largely accurate regarding a topic that is of considerable interest to both researchers and the public at large. My primary concern with this piece is that it overstates scientific confidence in the linkages between Arctic sea ice loss and mid-latitude weather (especially regarding connections to specific events, like Hurricane Sandy) and fails to make clear that this area remains a topic of very active research. It also uses some language that trends toward hyperbolic, especially in discussing “superstorms”. Jessica Liptak Postdoctoral Research Fellow, University of Michigan: The article spans a wide range of related, but complex topics. Had it focused on just one, such as the potential link between Arctic sea ice melt and midlatitude atmospheric blocking patterns, the writer could have perhaps provided a more thorough summary of what researchers know and, just as importantly, how confident they are in their results. While this article provides insight on how Arctic warming and melting sea ice may affect midlatitude weather, it misleadingly presents the sea ice-albedo feedback as the only contributor to Arctic temperature amplification. Tim Woollings Lecturer, University of Oxford: The article seems to faithfully summarise the views of these scientists. However, this is a relatively small group of researchers, and many in the field would give a more cautious story given current uncertainties. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from the article; comments and replies are from the reviewers. 1. The Arctic is warming faster than the rest of the planet—partly because of the loss of sunlight-reflecting ice and snow, but also for other reasons. “The chain of events that links the melting Arctic with weather to the south begins with rising global temperatures causing more sea ice to melt. Unlike on the Antarctic continent, melting ice here exposes dark ocean beneath, which absorbs more sunlight than ice and warms further. This feedback loop is why the Arctic is heating up much faster than the rest of the planet.” Jessica Liptak Postdoctoral Research Fellow, University of Michigan: This statement correctly identifies how the sea ice-albedo feedback contributes to Arctic temperature amplification, but incorrectly implies that it is the only process responsible for the enhanced warming. While some studies have concluded that the sea ice-albedo feedback is the primary driver of Arctic amplification [1-2]​​, other feedbacks [3-4]​​, internal atmospheric variability, and decadal variations in sea surface temperature and ocean circulation [​5]​​, may have contributed as much, if not more, to the Arctic tropospheric temperature increase. 1. Screen and Simmonds (2010) The central role of diminishing sea ice in recent Arctic temperature amplification, Nature 2. Taylor et al. (2014) A Decomposition of Feedback Contributions to Polar Warming Amplification, Journal of Climate 3. Pithan and Mauritsen (2014) Arctic amplification dominated by temperature feedbacks in contemporary climate models, Nature Geoscience 4. Winton (2006) Amplified Arctic climate change: What does surface albedo feedback have to do with it?, Geophysical Research Letters 5. Perlwitz et al. (2015) Arctic Tropospheric Warming: Causes and Linkages to Lower Latitudes, Journal of Climate 2. The faster rate of warming in the Arctic has the potential to influence weather in the mid-latitudes, but links to specific weather patterns are still topics of active research. “The jet stream forms a boundary between the cold north and the warmer south, but the lower temperature difference means the winds are now weaker. This means the jet stream meanders more, with big loops bringing warm air to the frozen north and cold air into warmer southern climes.” Daniel Swain Climate Scientist, University of California, Los Angeles: The statement regarding what the jet stream is (a “boundary between cold north and warmer south”) is essentially correct, and there is indeed evidence that the north-south temperature difference has decreased in some regions.[1] But there remains considerable scientific uncertainty regarding whether the jet stream is actually “meandering more” in a general sense, and whether these large jet stream meanders are actually caused by sea ice loss.[2-3] 1. Francis and Skific (2015) Evidence for a wavier jet stream in response to rapid Arctic warming, Environmental Research Letters 2. Barnes and Screen (2015) The impact of Arctic warming on the midlatitude jet‐stream: Can it? Has it? Will it?, Wiley Interdisciplinary Reviews: Climate Change 3. Screen and Simmonds (2013) Exploring links between Arctic amplification and mid-latitude weather, Geophysical Research Letters Stephen Vavrus Senior Scientist, University of Wisconsin-Madison: The first sentence is grounded in solid meteorology, since the strength of westerly winds aloft is basically proportional to the north-south temperature difference. The second sentence is also supported by evidence, although not quite as solidly. The sinuosity of the upper-level westerlies generally does vary inversely with the wind speed, but there are exceptions. When the jet stream meanders a lot, then warm air is brought northward and cold air spills southward. “Furthermore, researchers say, the changes mean the loops can remain stuck over regions for weeks, rather than being blown westwards as in the past. This “blocking” effect means extreme events can unfold.” Stephen Vavrus Senior Scientist, University of Wisconsin-Madison: First, I think the word should be “eastwards”, not “westwards”. Second, although the loops do sometimes remain stuck for weeks, the sentence makes it seem as if this is the new normal. Instead, a weaker jet stream ought to increase the persistence on various time scales, but more often being days instead of weeks. The second sentence is partly true, in that atmospheric blocking patterns often do cause extreme weather events, but extreme events can also occur under other conditions, including very strong jet stream winds (e.g. atmospheric rivers). “Severe ‘snowmageddon’ winters are now strongly linked to soaring polar temperatures, say researchers, with deadly summer heatwaves and torrential floods also probably linked.” Daniel Swain Climate Scientist, University of California, Los Angeles: Arctic temperatures have certainly been much higher than the long-term average in recent years, and the extreme warm anomalies this autumn and early winter have been particularly noteworthy. Further, there is a growing body of evidence linking Arctic sea ice loss and/or polar-amplified atmospheric warming to changes in mid-latitude atmospheric circulation*. However, this subject represents a very active area of research and there remains genuine scientific uncertainty regarding specific linkages between ongoing Arctic sea ice loss and specific kinds of extreme weather (like the heatwaves, floods, and snowstorms mentioned here). Moreover, the effects under consideration would likely have different regional manifestations. Therefore, the above statement overstates scientific confidence in such linkages and is overly broad in a geographic sense. Francis and Vavrus (2012) Evidence linking Arctic amplification to extreme weather in mid-latitudes, Geophysical Research Letters Cohen et al. (2014) Recent Arctic amplification and extreme mid-latitude weather, Nature Geoscience Overland et al. (2016) Nonlinear response of mid-latitude weather to the changing Arctic, Nature Climate Change Tim Woollings Lecturer, University of Oxford: “Strongly linked” is an overstatement here. There is some evidence, but I don’t think a majority of climate scientists would make claims as strong as these. “It’s safe to say [the hot Arctic] is going to have a big impact, but it’s hard to say exactly how big right now.” Tim Woollings Lecturer, University of Oxford: This statement is unclear. Arctic warming will clearly have a strong impact on the midlatitudes in the future (certainly by the end of the century). Whether it has had a noticeable effect so far is a lot less clear. “In those years, the jet stream deviated deeply southwards over those regions, pulling down savagely cold air. Prof Adam Scaife, a climate modelling expert at the UK’s Met Office, said the evidence for a link to shrinking Arctic ice was now good: ‘The consensus points towards that being a real effect.’” Stephen Vavrus Senior Scientist, University of Wisconsin-Madison: The first sentence is correctly describing how the jet stream tends to move equatorward during the negative phase of the North Atlantic (or Arctic) Oscillation [NAO and AO, respectively], which was very prevalent in those years. Negative phases of the NAO or AO strongly promote more extreme cold in middle latitudes during winter. As for a “consensus”, that depends a lot on who you ask. This topic of potential Arctic-middle latitude connections is a controversial one, so there isn’t a lot of consensus on the overall role of the Arctic at this point. I think the closest we have to a consensus is the persuasive evidence that sea ice loss in the Barents-Kara Seas during autumn-winter promotes extreme cold downstream over eastern Asia via a stronger Siberian High Pressure Cell. Tim Woollings Lecturer, University of Oxford: This refers to a southward shifted jet in response to sea ice loss (a negative North Atlantic Oscillation pattern). It’s not clear at all that this is the same kind of behaviour as suggested by the quoted scientists. “The connection between the vanishing Arctic ice and extreme summer weather in the northern hemisphere is probable, according to scientists, but not yet as certain as the winter link.” Tim Woollings Lecturer, University of Oxford: The winter link is not certain either. As above, there is some evidence for a North Atlantic Oscillation response but still several conflicting studies. Stephen Vavrus Senior Scientist, University of Wisconsin-Madison: Again, it depends who one talks to about whether “probable” is the correct term. There have been numerous articles making this claim and providing plausible evidence for it, but a well-accepted physical explanation has yet to be established, in my opinion. The dynamical mechanisms linking sea ice anomalies to mid-latitude weather during winter are easier to understand than those during summer. Different but more complex linkages might well exist during summer to explain some of the observational evidence correlating sea ice anomalies with extreme summer weather. “Another consequence of the fast melting Arctic raises the possibility that there may be even worse extreme weather to come, according to a few scientists: titanic Atlantic superstorms and hurricanes barreling across Europe.” Daniel Swain Climate Scientist, University of California, Los Angeles: This statement does not accurately describe an outcome that is widely supported in the scientific literature. It is certainly true that Arctic sea ice is decreasing at a rapid rate, and that further sea ice loss is highly likely in the future. It is also plausible, and supported by existing research, that present and future sea ice loss may alter the atmospheric circulation in ways that affect the likelihood of certain kinds of weather events*. But the claim regarding “Atlantic superstorms” and “hurricanes barreling across Europe” seems fairly hyperbolic. Overland et al. (2016) Nonlinear response of mid-latitude weather to the changing Arctic, Nature Climate Change Kug et al. (2015) Two distinct influences of Arctic warming on cold winters over North America and East Asia, Nature Geoscience Zhang et al. (2016) Persistent shift of the Arctic polar vortex towards the Eurasian continent in recent decades, Nature Climate Change “This means a region of the north Atlantic is becoming relatively cool and this exaggerates the contrast with tropical waters to the south, which is the driver for storms. In the worst case scenario, said the renowned climate scientist Prof James Hansen, this ‘will drive superstorms, stronger than any in modern times – all hell will break loose in the north Atlantic and neighbouring lands’.” Tim Woollings Lecturer, University of Oxford: I agree that the superstorm suggestion is very speculative. In one paper we looked at a similar scenario and saw a clear increase in the number of storms, but not their intensity, though that was just in one climate model. Brayshaw and Woollings (2009) Tropical and Extratropical Responses of the North Atlantic Atmospheric Circulation to a Sustained Weakening of the MOC, Journal of Climate “I would certainly not call such [superstorm] scenarios ridiculous,” said Coumou. “But it is speculative – we don’t have the hard evidence.” James Renwick Professor, Victoria University of Wellington: The superstorm scenario rests on a number of assumptions, especially that the rate of ice melt from Greenland (and Antarctica) will accelerate very rapidly. Definitely still in the realm of speculation.

https://science.feedback.org/review/stunning-new-data-indicates-el-nino-drove-record-highs-global-temperatures-david-rose-daily-mail/

-1.9

Daily Mail, by David Rose, Judith Curry, on 2016-11-26.

"Stunning new data indicates El Nino drove record highs in global temperatures..."

Contrary to what this article implies, the long term global temperature rise is known to be mostly due to human emissions of greenhouse gases. A strong El Niño event helped set a new record in annual global surface temperature in 2015 (and likely again in 2016) by boosting global temperatures on top of the long-term warming trend. This article is a textbook case of cherry picking—it selects only one record, ignores the limitations of the data it comments on, and forms an argument based on only a few months of a much longer record. This is akin to claiming that sea level rise has ended because high tide in one area has ebbed.See all the scientists’ annotations in context The article has been originally published by The Mail on Sunday and then published online on the Daily Mail‘s website. GUEST COMMENTS: Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: This is an incredibly misleading article. It cherry picks a dataset taking measurements 2 miles up in the atmosphere only over land areas that disagrees with the other two datasets that examine the same values. The author of the dataset they use specifically warns against using it due to errors in measurement times. Literally all other surface and satellite datasets show no corresponding massive decline, either over land or globally. The author is taking a normal modest cooling at the end of a large El Niño event and spinning it completely out of proportion. In reality, 2014, 2015, and 2016 have been the three warmest years on record not just because of a large El Niño, but primarily because of a long-term warming trend driven by human emissions of greenhouse gases. The modest decline in temperatures in recent months from the peak of the El Niño event is completely in line with what has happened during past large El Niño events and was expected by scientists. Stephan Lewandowsky Professor, University of Bristol: This article is flawed to perfection. Mr. Rose made the following inadvisable choices: 1. Ignore the surface temperature record and use only satellite data. Satellites do not measure temperature, they measure microwave radiation, which can be related to an estimate of temperature by use of a computer model. The resulting estimate is, however, not only of temperature at the surface of the Earth—which is where we live—but includes temperature at altitudes of thousands of feet—where no one is trying to farm or grow tomatoes. 2. Ignore two-thirds of the satellite record. Most of the Earth is covered in ocean, and global warming is called global warming because it is global—that is, it includes the oceans. 3. Ignore the trend and focus on two data points. A long-standing trick of people who deny the overwhelming scientific consensus regarding climate change is to cherry-pick isolated observations. The only way to support the claim of a 1-degree drop in the satellite record is by comparing February 2016 to October 2016. This drop, however, is merely weather that is superimposed on the long-term climatic trend. Steven Sherwood Professor, University of New South Wales: The discussion in the article of a disagreement among scientists as to whether the record-breaking global heat in 2015 and again in 2016 was “due to El Niño” vs. “due to global warming” is completely bogus. Both global warming and El Niño, added together, produced these records. El Niño by itself could never have produced such a warm planet as we have now. Everyone, including NASA’s Gavin Schmidt, has been pointing out for some time that temperatures would dip for a while once the El Niño faded, but that’s just a bump on the road to a warmer and warmer planet. REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Ed Hawkins Principal Research Fellow, National Centre for Atmospheric Science: Overall the article is made highly misleading by omitting critical information and cherry-picking one particular dataset and time period. It also incorrectly interprets comments from climate scientists. Benjamin Horton Professor, Earth Observatory of Singapore: The claim that global land temperatures have plunged by a record margin is false because: (1) the author cherry picks the data, relying on the satellite record of Earth’s temperature, which only dates to 1978 rather than the surface temperature record which dates to the 19th century. Using the full dataset the decrease in land-based temperature is NOT a record drop; (2) the author IGNORES THE OCEANS. When combining both the land and ocean, there is not a record fall in the satellite record; and (3) the surface temperature record shows an unmistakably upward trend, irrespective of year-to-year wiggles. Victor Venema Scientist, University of Bonn, Germany: It is a pity the rating scale does not allow for rating below “very low”. Had the article honestly shown a graph of the global surface temperature increase in the last century every reader would have seen how deceptive David Rose’s article is. Kyle Armour Assistant Professor, University of Washington: It is well known that global temperature falls after receiving a temporary boost from El Niño. The author cherry-picks the slight cooling at the end of the current El Niño to suggest that the long-term global warming trend has ended. It has not. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from David Rose; comments and replies are from the reviewers. 1.Recent record global surface temperatures are primarily the result of the long-term, human-caused warming trend. A smaller boost from El Niño conditions has helped set new records in 2015 and 2016. “Some scientists, including Dr Gavin Schmidt, head of Nasa’s climate division, have claimed that the recent highs were mainly the result of long-term global warming.” Victor Venema Scientist, University of Bonn, Germany: Dr. Gavin Schmidt, who is head of NASA’s Goddard Institute for Space Studies and not any of the NASA divisions, is right. The long-term warming of about 1°C globally—and more over land or in the Northern Hemisphere—is much larger than the El Niño fluctuations. Source: Global Warming Index “Others have argued that the records were caused by El Nino […] The new fall in temperatures suggests they were right.” Ed Hawkins Principal Research Fellow, National Centre for Atmospheric Science: Incorrect. We have seen more than 1°C of warming which is largely due to human activities. The strong El Niño has added around 0.1°C temporarily. Therefore, the largest cause of the record temperatures is human activities. “This means it is possible that by some yardsticks, 2016 will be declared as hot as 2015 or even slightly hotter – because El Nino did not vanish until the middle of the year.” Victor Venema Scientist, University of Bonn, Germany: It is virtually certain that 2016 will be warmer than 2015. See for example this estimate of the 2016 average temperature based on the GISS data up to October. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: Even without the big El Niño spike, 2016 will be the hottest year on record, and 2015 the second hottest. Scientists have methods to remove the effect of El Niño on the temperature record. We can also see this in a simple example where we just remove the big El Niño-related temperature spike, but 2016 remains the warmest year in the surface temperature record: “Dr. Schmidt also denied that there was any ‘pause’ or ‘hiatus’ in global warming between the 1998 and 2015 El Ninos.” Victor Venema Scientist, University of Bonn, Germany: If you want to cherry pick 1998 as the beginning year—a year in which the temperature was high due to El Niño—it would at least be fair to stop in 2016, not 2015, because 2016 is the year that the temperatures were highest due to El Niño. If you do so, there is clearly no “slowdown”. Better would be not to cherry-pick a specific period. The long-term trend is clearly warming and statistics do not indicate any decline in the warming rate. Since 2016, I would argue you no longer need statistics to see this. Just look at the complete graph. “Professor Judith Curry, of the Georgia Institute of Technology, and president of the Climate Forecast Applications Network, said yesterday: ‘I disagree with Gavin. The record warm years of 2015 and 2016 were primarily caused by the super El Nino.’” Kyle Armour Assistant Professor, University of Washington: It seems kind of pointless to try to precisely attribute why one year was warmer or cooler than the last; this is basically just due to climate variability (including but not limited to El Niño). The broader point is that all evidence suggests that the long-term global surface warming trend has continued. There is no evidence that the rate of warming since 1998 is statistically different from the long-term trend since 1950. 2. The article makes its case by relying only on cherry-picked data from specific datasets on short periods. “The news comes amid mounting evidence that the recent run of world record high temperatures is about to end.” Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: The modest decline in temperatures in the past few months is a normal reversion after the end of the El Niño event. It has relatively little impact on the longer-term warming trend, which is the most scientifically relevant metric of climate change. Victor Venema Scientist, University of Bonn, Germany: We have had 3 record warm years: 2014, 2015, and likely 2016. Also when Bayern München loses a game, they are still be best team in Germany—when 2017 is not again a record year, global warming will continue. “The fall, revealed by Nasa satellites, has been caused by the end of El Nino” Victor Venema Scientist, University of Bonn, Germany: The temperature estimates come from passive microwave radiometers. These instruments’ prime task is estimating air humidity for meteorology—weather prediction. Thus most of the these instruments actually flew on NOAA satellites. It should be noted that they were not designed to be used for long-term climate monitoring. Steven Sherwood Professor, University of New South Wales: Temperature averages from satellite-based detectors are very noisy, and tend to exaggerate swings due to El Niño compared with other data sources. I would not attach much significance to big upswings or downswings over periods of only a few months, especially when other indicators, like sea ice, are suggesting acceleration of warmth. The long-term upward trend is clear in every source of data we have. “Global average temperatures over land have plummeted by more than 1C since the middle of this year – their biggest and steepest fall on record.” Victor Venema Scientist, University of Bonn, Germany: It is known that El Niño, an oscillation in the tropical Pacific, is a cause of short-term fluctuations of the temperature and precipitation. This should not be confused with long-term warming. This is clearly illustrated by this graph below that shows the warming of El Niño years, La Niña years (the opposite of El Niño), and neutral years individually. Victor Venema Scientist, University of Bonn, Germany: The image in the Daily Mail is deceptive as it only shows the part of the data (in the red box of the graph below). With all the problems of this dataset, it also shows long-term warming if you look at the full period.Ed Hawkins Principal Research Fellow, National Centre for Atmospheric Science: The time series used in the central image is highly misleading, as it only shows some of the data available and therefore disguises the increase seen before the chosen period. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: This is not true for global surface temperatures, not true for land surface temperatures, not true for global temperatures 2 miles up in the atmosphere, and not true for two of the three datasets that provide temperatures 2 miles up in the atmosphere only over land areas. It’s a truly breathtaking example of cherry-picking. Furthermore, the folks who created the dataset that Rose cites (Remote Sensing Systems) note that there is a serious error in their data and warn:“The lower tropospheric (TLT) temperatures have not yet been updated at this time and remain V3.3. The V3.3 TLT data suffer from the same problems with the adjustment for drifting measurement times that led us to update the TMT dataset. V3.3 TLT data should be used with caution.” “According to the satellites, the late 2016 temperatures are returning to the levels they were at after the 1998 El Nino.” Victor Venema Scientist, University of Bonn, Germany: Not based on any evidence. Just like the warming peak due to El Niño was higher in 2016 than in 1998, the period after 2016 will be warmer than the years after 1998 due to the progress of global warming. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: Even according to satellite records, which have their issues, this is not remotely the case:

https://science.feedback.org/review/daily-mail-claim-2016-global-temperature-record-misleading/

Misleading

Daily Mail, David Rose, 2016-11-26

El Niño drove record highs in global temperatures suggesting rise may not be down to man-made emissions.

Misrepresents a complex reality: Record highs in global surface temperatures in 2016 are due to the superposition of an El Niño event on top of the warming effect of human greenhouse gas emissions, so blaming the record only on El Niño paints a simplistic picture.

The continuing rise of global temperature is mostly due to human emissions of greenhouse gases. A strong El Niño event helped set a new record in annual global surface temperature in 2016.

Stunning new data indicates El Niño drove record highs in global temperatures suggesting rise may not be down to man-made emissions.

Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: Even without the big El Niño spike, 2016 will be the hottest year on record, and 2015 the second hottest. Scientists have methods to remove the effect of El Niño on the temperature record. We can also see this in a simple example where we just remove the big El Niño-related temperature spike, but 2016 remains the warmest year in the surface temperature record: The modest decline in temperatures in the past few months is a normal reversion after the end of the El Niño event. It has relatively little impact on the longer-term warming trend, which is the most scientifically relevant metric of climate change. Steven Sherwood Professor, University of New South Wales: Temperature averages from satellite-based detectors are very noisy, and tend to exaggerate swings due to El Niño compared with other data sources. I would not attach much significance to big upswings or downswings over periods of only a few months, especially when other indicators, like sea ice, are suggesting acceleration of warmth. The long-term upward trend is clear in every source of data we have. Victor Venema Scientist, University of Bonn, Germany: It is known that El Niño, an oscillation in the tropical Pacific, is a cause of short-term fluctuations of the temperature and precipitation. This should not be confused with long-term warming. This is clearly illustrated by this graph below that shows the warming of El Niño years, La Niña years (the opposite of El Niño), and neutral years individually.

https://science.feedback.org/review/great-barrier-reef-australia-coral-die-off-doyle-rice-usa-today/

1.6

USA Today, by Doyle Rice, on 2016-11-29.

"Australia’s Great Barrier Reef has worst coral die-off ever"

This article in USA Today reports on the latest survey of mass coral bleaching on the Great Barrier Reef released by the Australian Research Council Centre of Excellence for Coral Reef Studies. This year, the northern portion of the reef has seen the worst bleaching ever observed with two-thirds of coral dead on average—even more in some locations. Southern sections of the reef experienced much less bleaching and death because of slightly cooler water. The article correctly notes that climate change is making this kind of mass bleaching event more frequent, putting tropical reefs at risk. Reefs are ecosystems incredibly rich in biodiversity, and they provide economic value through tourism, fishing, and protection against coastal erosion.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Mark Eakin Scientist, Coordinator of NOAA’s Coral Reef Watch, National Oceanic and Atmospheric Administration: In general, the article got this one almost completely right, with one of my two quibbles being in one of the experts’ quotes. It is unfortunate, however, that the article didn’t put this story in the context of the global coral bleaching event that is still underway—currently hitting hardest in Micronesia and the Marshall Islands. Katrin Meissner Professor, University of New South Wales: This article is mostly accurate. The author made one overstatement (that we will see yearly massive bleaching events at the Great Barrier Reef within the next decade). It should be noted, though, that the frequency of massive bleaching events is increasing, will continue to increase in the near future, and that these events do not need to occur annually to kill the reef. The variability of El Niño Southern Oscillation on top of the background warming trend of surface temperatures means that we will exceed the bleaching thresholds more frequently. In the future, the reefs won’t have time to recover between these events. James Renwick Professor, Victoria University of Wellington: This is a very good article highlighting one of the world’s biodiversity hotspots and the grave risks it faces. One of two of the comments and ideas are off the mark, but it is largely factually correct. Lauren Simkins Assistant Professor, University of Virginia: Coral bleaching is a visual reminder of the influence of climate change on the world’s oceans and ecosystems. The article presents findings that support a massive bleaching event this year and some of the ecological and economic consequences of coral bleaching. Although lacking in key scientific references to support claims, the article is insightful and unbiased. John Bruno Professor, The University of North Carolina at Chapel Hill: I concur with my colleagues that this is mostly an accurate article. A few points are exaggerated, as we all noted in the annotated version. And to be clear, this may well be the worse die off on the Great Barrier Reef, but we’ve been seeing die offs of this magnitude and geographic scope around the world for decades. For example, coral reefs across the Caribbean experienced a die off of similar-to-larger scope 35 years ago. My entire career, I’ve been studying “post mass-coral die off” reefs in Jamaica, Belize, Cuba, etc. So in this regard, the event isn’t especially notable. The real lesson of the GBR coral mortality of 2016 isn’t that ocean warming is causing mass-coral die offs – we’ve known that for a quarter century. It is that even the world’s most remote, well-managed, and otherwise pristine reefs are susceptible. Many of my colleagues have assumed and argued that ocean warming only causes mass coral mortality in the presence of other insults to the reef. Stressors like overfishing, pollution, tourism, etc. that were believed to weaken “natural resilience” to ocean warming. I co-authored a paper earlier this year* that found that reef isolation had no effect on coral loss – the world’s most isolated reefs, free from local human impacts, were just as degraded in terms of the amount of remaining living coral as reefs adjacent to large population centers. The bottom line is that no form of local management can save reefs from carbon emissions. Bruno and Valdivia (2016) Coral reef degradation is not correlated with local human population density, Nature scientific reports.Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from Doyle Rice; comments and replies are from the reviewers. 1.This year, the northern section of Australia’s Great Barrier Reef experienced the worst bleaching of corals ever observed. (Corals “bleach” when water temperatures increase beyond a tolerable range.) “Scientists confirm a mass bleaching event on the Great Barrier Reef this year has killed more corals than ever before, with more than two thirds destroyed across large swathes of the biodiverse site.” Mark Eakin Scientist, Coordinator of NOAA’s Coral Reef Watch, National Oceanic and Atmospheric Administration: Actually, this is an underestimate as the “25% of the worst affected reefs (the top quartile), losses of corals ranged from 83-99%.” How much coral has died in the Great Barrier Reef’s worst bleaching event? “When water temperatures become too high, coral becomes stressed and expels the algae, which leave the coral a bleached white color.” Mark Eakin Scientist, Coordinator of NOAA’s Coral Reef Watch, National Oceanic and Atmospheric Administration: The article should have noted that, while injured and starving, bleached corals are still alive. When thermal stress is severe or prolonged, corals often die. Thermally-stressed corals also frequently die due to disease outbreaks. NOAA Coral Reef Conservation Program Infographic Gallery Burge et al (2014) Climate Change Influences on Marine Infectious Diseases: Implications for Management and Society, Annual Review: of Marine Science “The good news, scientists said, was that central and southern sections of the reef fared far better, with “only” 6% and 1% of the coral dead, respectively.” Mark Eakin Scientist, Coordinator of NOAA’s Coral Reef Watch, National Oceanic and Atmospheric Administration: The pattern of warming this year resulted in the highest thermal stress being located in the northern part of the Great Barrier Reef. This can be seen in the coral bleaching products from NOAA’s Coral Reef Watch. Source: NOAA Coral Reef Watch 2.Global warming is raising seawater temperatures, leading to episodes of widespread coral bleaching. These episodes typically occur during El Niño conditions, which regionally boost water temperature further. “Stress from unusually warm ocean water heated by man-made climate change and the natural El Niño climate pattern caused the die-off.” Julia Cole Professor, The University of Arizona: Yes, human-caused warming boosts the background temperature, so that warming associated with El Niño can now reach levels intolerable by corals. Mark Eakin Scientist, Coordinator of NOAA’s Coral Reef Watch, National Oceanic and Atmospheric Administration: Roughly speaking, the El Niño may have added a quarter of a degree C to the global average in 2015/16, while the greenhouse-gas-related warming trend has added twice that much to the average values since the 1980s. It’s also important to note that this is only one part of a global coral bleaching event that has been occurring since mid-2014. NOAA declares third ever global coral bleaching event “Mass coral bleaching is a new phenomenon and was never observed before the 1980s as global warming ramped up.” Mark Eakin Scientist, Coordinator of NOAA’s Coral Reef Watch, National Oceanic and Atmospheric Administration: Correct. Baker et al (2008) Climate change and coral reef bleaching: An ecological assessment of long-term impacts, recovery trends and future outlook, Estuarine, Coastal and Shelf ScienceJulia Cole Professor, The University of Arizona: On the Great Barrier Reef, I believe this is true. Global (especially tropical) temperatures took a jump upwards in the late 1970s, providing the extra warmth that puts corals in danger. “[…]looking to the future, mass coral bleaching on the Great Barrier Reef will likely be an annual phenomenon within a decade, Torda said.” Mark Eakin Scientist, Coordinator of NOAA’s Coral Reef Watch, National Oceanic and Atmospheric Administration: This may turn out to be true but most studies place annual bleaching, especially on the Great Barrier Reef, a bit further out—perhaps 2050. van Hooidonk et al (2013) Temporary refugia for coral reefs in a warming world, Nature Climate ChangeKatrin Meissner Professor, University of New South Wales: This sentence is an overstatement. See, for example, Meissner et al. (2012)*: “By year 2030, 66–85% of the reef locations considered in this study would experience severe bleaching events at least once every 10 years. Regardless of the concentration pathway, virtually every reef considered in this study (>97%) would experience severe thermal stress by year 2050.” Having said that, mass coral bleaching events do not need to be an annual phenomenon to kill the reef. Coral reefs need years to recover from extreme bleaching events, which means that even a decadal occurrence of severe bleaching will not give the reef enough time to ever recover. While this sentence is an overstatement, the impact on the reef is the same. Meissner et al (2012) Large-scale stress factors affecting coral reefs: open ocean sea surface temperature and surface seawater aragonite saturation over the next 400 years, Coral Reefs

https://science.feedback.org/review/higher-global-temperatures-sea-ice-record-lows-poles-brandon-miller-cnn/

2

CNN, by Brandon Miller, on 2016-11-19.

"Amid higher global temperatures, sea ice at record lows at poles"

This CNN article discusses the unprecedented recent warm sea surface and air temperatures leading to the record low Arctic extent. It also explores the potential influence this long-term trend of sea ice loss may have on the polar vortex and weather patterns in the midlatitudes. Scientists reviewing the article found that it is an accurate and insightful summary of current scientific knowledge, which indicates that warming is driving a long-term decline in Arctic sea ice coverage—though sea ice at both poles is subject to shorter-term variability, as well.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Michel Tsamados Lecturer (Assistant Professor), University College London: The article does a good job of conveying our current understanding of the state of the sea ice in the 21st century. The very low total Arctic and Antarctic sea ice extent in October 2016 is a clear outlier with respect to the last ~40 years. Such an extreme event is a combination of particular weather patterns in both hemispheres superimposed on the rapid temperature rise observed in the Arctic (at twice the global rate – the so called ‘polar amplification’). Jan Lenaerts Assistant Professor, University of Colorado, Boulder: Well outlined and balanced article, describing the evident link between low sea ice and climate warming and the melt-albedo feedback, but also mentioning the role of weather and short-time variability. Jennifer Francis Senior Scientist, Woods Hole Research Center: This is an excellent summary of the Arctic’s bizarre behavior recently and through most of 2016. James Renwick Professor, Victoria University of Wellington: An excellent explainer piece. Well written and grounded in science. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from Brandon Miller; comments and replies are from the reviewers. 1. Arctic sea ice extent is declining rapidly as a result of climate change. Antarctic sea ice is expected to shrink eventually as well, but has been so far more influenced by natural variability. “While record low sea ice is nothing new in the Arctic, this is a surprising turn of events for the Antarctic. Even as sea ice in the Arctic has seen a rapid and consistent decline over the past decade, its counterpart in the Southern Hemisphere has seen its extent increasing.” James Renwick Professor, Victoria University of Wellington: Exactly. The “upward trend” has been big news, but in the last two years, sea ice extent around the Antarctic has taken a nose-dive. Sea ice extent anomalies for the months ofOctober (1979-2016) in the Antarctic (up) and Arctic (down). Source: NSIDC “Skeptics have long pointed to ice gain in the Southern Hemisphere as evidence climate change wasn’t occurring, but scientists warned that it was caused by natural variations and circulations in the atmosphere.” Jan Lenaerts Assistant Professor, University of Colorado, Boulder: This is slightly confusing, since it can refer to either sea ice gain or land ice gain (which were both mentioned by “skeptics”). The sea ice gain since 2000 has been attributed to natural, decadal variability in the tropical Pacific*. Land ice gain is a false claim, and mostly refers to slight thickening of the East Antarctic interior, which is more than compensated by dynamic ice loss in West Antarctica. Meehl et al (2016) Antarctic sea-ice expansion between 2000 and 2014 driven by tropical Pacific decadal climate variability, Nature Geoscience “It “certainly puts the kibosh on everyone saying that Antarctica’s ice is just going up and up,” Meier said.” Michel Tsamados Lecturer (Assistant Professor), University College London: I agree that the statement that Antarctic sea ice going up and up is a misconception when looked at over larger time scales. On the other hand it is also true that over the satellite area Antarctic sea ice has increased in extent (a bit) every month of the year (see NSIDC time series) October is probably the month with the weakest positive trend. Therefore I believe that it is more important to explain that while the transient response of Antarctic sea ice is more complex than in the Arctic, the end state (equilibrium) is also one with polar amplification, increased temperatures and sea ice decline, in both hemisphere. “For what appears to be the first time since scientists began keeping track, sea ice in the Arctic and the Antarctic are at record lows this time of year.” Michel Tsamados Lecturer (Assistant Professor), University College London: While we have a very clear picture of the sea ice concentration only over the satellite era (1979-present) there are other measurements available that are more or less direct, ranging from whaling and shipping log books (showing higher sea ice extent over the past 100 years) to paleo-climate reconstruction (proxies) over thousands to million of years. [more about ‘polar amplification’ in past climate] “It’s far too early to tell if what we are seeing in the Arctic, and now the Antarctic, is a sharp shift towards warmer poles with less ice. Scientists are quick to point out that weather in these regions can change quickly, but this is another expected result of climate change.” Julienne Stroeve Senior Research Scientist, University College London: Certainly the loss of sea ice is largely a result of warming from increased atmospheric concentrations of CO2. So it’s not surprising to see the changes in the Arctic. Climate models also predict that Antarctic sea ice will decline eventually, especially once the ozone hole recovers. There is some evidence* that the ozone hole has led to stronger circumpolar winds that spread the Antarctic sea ice cover out from the continent and since there is no land to bound the sea ice (like in the Arctic) it can expand towards the equator until it reaches warmer ocean temperatures. Arblaster and Meehl (2006) Contributions of External Forcings to Southern Annular Mode Trends, Journal of Climate Turner and Overland (2009) Contrasting climate change in the two polar regions, Polar Research 2. The current lack of Arctic sea ice growth can be partly explained by the “ice-albedo” feedback—the fact that with less sea ice, the exposed ocean water is able to absorb more solar energy, accelerating the warming and melting process. “‘The interaction between Arctic ocean temperatures and the loss of ice formation leading to continuing record minimums is clearly a climate change signal,’ said Thomas Mote, a geography research professor at the University of Georgia.” James Renwick Professor, Victoria University of Wellington: Yes. The “ice-albedo feedback” has been evident in the Arctic for some years, contributing to “polar amplification”—the effect where polar latitudes warm at around twice the rate of the globe as a whole. “Temperatures in the Arctic have soared recently, and scientists are struggling to explain exactly why.” Jennifer Francis Senior Scientist, Woods Hole Research Center: The only quibble I have with this article is this statement. I’d say that we have a fairly good understanding of the causes of this warm episode. As mentioned in the article, a very diminished ice cover this summer allowed additional solar energy to be absorbed by the Arctic Ocean, which is then released back to the atmosphere in fall that in turn retards refreezing. Additional moisture is also evaporated from the open ocean, which not only traps additional heat as a greenhouse gas, but also tends to form more clouds that also trap heat. An unusually wavy jet-stream pattern has also transported extra heat and moisture from lower-latitude regions into the Arctic, adding to the warmth. We know many self-reinforcing mechanisms operate in the Arctic, so when some heat shows up there (think greenhouse gases, moisture, etc.), its effects are amplified. This has been understood for a long time, but perhaps the pace of this warming is somewhat unexpected. “To make matters worse, the water temperatures in the Arctic Ocean are several degrees above average, which is an expected result of having less sea ice.” Julienne Stroeve Senior Research Scientist, University College London: Generally, the absorbed solar radiation leads to enhanced ocean temperatures in the mixed layer, so with summers of less ice the ocean mixed layer temperatures are usually warmer than average. Though even that is more driven by the timing of when the sea ice retreats. If it retreats early in the melt season when the sun is still high in the sky then you get more ocean warming, but if like in 2012 the ice retreats rapidly in August, it doesn’t have the same impact on ocean temperatures because the sun is already starting to set. But while this may be part of the explanation for warmer ocean temperatures at the moment, in the Barents Sea it is actually a result of warm Atlantic waters entering the Arctic. I have spoken with oceanographers about this and the sea surface temperature anomalies are a result of stronger inflow to the Barents Sea and along the west coast of Svalbard. The strong northwards flow of Atlantic water is also consistent with the more southerly winds this November that have helped to bring in warm air temperatures.

https://science.feedback.org/review/the-phony-war-against-co2-the-wall-street-journal-rodney-nichols-harrison-schmitt/

-2

The Wall Street Journal, by Harrison Schmitt, Rodney Nichols, on 2016-10-31.

"The Phony War Against CO2"

This commentary in the Wall Street Journal by Rodney Nichols and Harrison Schmitt tries to argue that CO2 emitted by humans is, overall, “beneficial”–particularly for agriculture. To do so, the authors ignore all the evidence of the negative impacts of increasing CO2 concentrations in the atmosphere (due to climate change and ocean acidification, for example). The commentary relies on claims that are not supported by any evidence, like the assertion that more CO2 in the atmosphere has helped to reduce poverty. The authors invite the reader to “check the facts” but do not apply that maxim to themselves. Instead of referring to published scientific research, the article draws heavily from information created by an advocacy group that exists to promote CO2 emissions as beneficial. Taken as a whole, the body of scientific evidence clearly shows that this is not the case.See all the scientists’ annotations in contextGUEST COMMENTS: Wolfgang Cramer Professor, Directeur de Recherche, Mediterranean Institute for Biodiversity and Ecology (IMBE): The article speaks about scientific questions under an “opinion” banner—as if questions about the role of CO2 in the Earth system could be a matter of opinions. Virtually every single point in the article can be easily proven wrong by referral to standard textbook knowledge. For the major final conclusion “With more CO2 in the atmosphere, the challenge [to feed additional 2.5 billion people] can and will be met.“, there is absolutely no scientific credibility, nor support in the scientific literature—it is pure fantasy.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. William Anderegg Associate Professor, University of Utah: The opinion article makes sweeping assertions that are not in line with the scientific understanding. The conclusions on CO2 uniformly benefiting agriculture are simply misleading—yes, CO2 can help plants but higher temperatures and more drought and pests with climate change also hurt plants. Timothy Osborn Professor, University of East Anglia, and Director of Research, Climatic Research Unit: The article presents a biased view by understating the degree and impacts of global warming while overstating or simplifying the benefits of CO2 fertilisation. James Renwick Professor, Victoria University of Wellington: The article is full of half-truths, untruths, and red herrings. Casting increased CO2 as a benefit to humankind, without considering the impacts and risks associated with a changing climate, is dangerous and irresponsible. Lauren Simkins Assistant Professor, University of Virginia: The lack of distinction between the role of solid particulates and greenhouse gases in the atmosphere makes many of the authors’ claims false and misleading. The article does not present a complete or accurate discussion of climate change, its causes, and its societal influence. The authors state that readers should ‘check the facts’ regarding climate change, but have presented us with little scientific support for their own claims. Victor Venema Scientist, University of Bonn, Germany: This has nothing to do with science. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from Harrison Schmitt and Rodney Nichols; comments and replies are from the reviewers. 1. The negative impacts of continued CO2 emissions are significant and serious. The authors only find human emissions of CO2 beneficial by ignoring all the reasons it is harmful. “Unlike genuine pollutants, carbon dioxide (CO2) is an odorless, colorless gas. Every human being exhales about two pounds of CO2 a day, along with a similar amount of water vapor. CO2 is nontoxic to people and animals” Timothy Osborn Professor, University of East Anglia, and Director of Research, Climatic Research Unit: This is a diversionary tactic: the concern about CO2 is not about its smell, its colour or its direct toxicity; instead it is about its effect on the Earth’s climate. So it is a strawman statement that may be easily demolished but not relevant to the concern about CO2 and climate change. Victor Venema Scientist, University of Bonn, Germany: There are many toxic gases that are odorless and colorless. The best known one is, like CO2, also related to combustion: carbon monoxide (CO). “But a myth persists that is both unscientific and immoral to perpetuate: that the beneficial gas carbon dioxide ranks among hazardous pollutants. It does not.” James Renwick Professor, Victoria University of Wellington: This is semantics. Some call carbon dioxide a “pollutant” and others don’t. What is relevant is that the huge amount of CO2 that humanity has put into the atmosphere is changing the climate significantly. The hazard comes from changes to precipitation and extremes, leading to reduced food security and water availability. No wonder the Pentagon rates climate change as a critical threat to US national security. Just look at what’s happening in Syria and north Africa, on the back of a severe drought and a spike in food prices. Reference: Kelley et al (2015) Climate change in the Fertile Crescent and implications of the recent Syrian drought. Proceedings of the National Academy of Sciences “[CO2] is also a greenhouse gas which helps maintain earth at a habitable temperature.” Wolfgang Cramer Professor, Directeur de Recherche, Mediterranean Institute for Biodiversity and Ecology (IMBE): While the presence of CO2 has warmed the atmosphere to “habitable” temperatures, the additional increase of it will bring temperatures way outside habitable ranges in many regions including the oceans, as well as disturbing the water cycle and acidifying the oceans. “But observations, such as those on our CO2 Coalition website, show that increased CO2 levels over the next century will cause modest and beneficial warming—perhaps as much as one degree Celsius (1.8 degrees Fahrenheit)” James Renwick Professor, Victoria University of Wellington: That [1 °C warming] is an absolute best-case scenario, if significant mitigation action is taken urgently. Increased CO2 leads to warming, which leads to increased atmospheric water vapor, less ice, and other feedbacks. A doubling of CO2 concentrations would lead to about 3 °C warming. Timothy Osborn Professor, University of East Anglia, and Director of Research, Climatic Research Unit: Projections of future warming can’t be made from observations alone: we need understanding of the mechanisms and physical processes. Neither of these are provided by the quoted website, which instead contains inaccurate articles about supposed adjustments to temperature data and claiming a new ‘little ice age’ is already here—both of which have been shown to be incorrect by scientific research. (For example, section 1.3.2 of the Fourth Assessment Working Group I IPCC report compared global temperature records from various vintages and found broad consistency.) “The costs of emissions regulations, which will be paid by everyone, will be punishingly high and will provide no benefits to most people anywhere in the world.” Lauren Simkins Assistant Professor, University of Virginia: This is simply not accurate. Global warming is a global issue that, for example, affects global coastal populations, marine ecology, crop stability, and the area of habitable land. Humans, especially in countries with the largest carbon emissions, have been successfully altering the entire Earth system; therefore, climate change is currently the most global issue that we face and will continue to face in the coming centuries. Wolfgang Cramer Professor, Directeur de Recherche, Mediterranean Institute for Biodiversity and Ecology (IMBE): It is unclear what costs are referred to here. The regulations themselves cost nothing. The reductions of emissions will avoid huge damage costs and also produce economic benefits in other than the fossil-fuel dependent economic sectors. It is the damage costs that will be “paid by everyone”, not the emission reductions. 2. Continued CO2 emissions will not improve future crop production. The IPCC report concludes that the net result of further climate change will be to hinder global crop yields. “In 2013 the level of U.S. farm output was about 2.7 times its 1948 level, and productivity was growing at an average annual rate of 1.52%. From 2001 to 2013, world-wide, global output of total crop and livestock commodities was expanding at an average rate of 2.52% a year[…] Along with better plant varieties, cropping practices and fertilizer, CO2 has contributed to this welcome increase in productivity.” G Philip Robertson,Professor, Michigan State University: In general, CO2 has had a positive effect on crop growth, but it’s impossible to separate historical effects from the greater effects of genetics and nitrogen and other inputs. However, it’s generally considered to be a fraction of those. We know better future effects because we have CO2 fertilization experiments in the field comparing present to future CO2 levels. Those experiments suggest that corn may have about a 1% gain [because of increased CO2] and soybeans 3-4 times that. However, these gains will almost certainly be offset by yield declines associated with the temperature increases caused by elevated CO2, which are well known. Historically, it’s worth noting that we had elevated CO2 long before we had the green revolution, and crop yields didn’t increase much until the green revolution. You can see this in graphs of average US corn yields from 1900. Source: University of Nebraska-Lincoln “With more CO2 in the atmosphere, the challenge [feeding 2.5 billion more people] can and will be met.” Wolfgang Cramer Professor, Directeur de Recherche, Mediterranean Institute for Biodiversity and Ecology (IMBE): There is absolutely no scientific study that would support such a conclusion. And even if there was no climate effect of CO2, a simple speculative growth enhancement by CO2 could not produce such an effect. James Renwick Professor, Victoria University of Wellington: This is very naïve. Many factors control food production. If further large changes in climate come to pass, no amount of extra CO2 will improve food security. “Feeding these people and assuring them a comfortable living standard should be among our highest moral priorities.” Lauren Simkins Assistant Professor, University of Virginia: Climate change and poverty go hand in hand, as developing countries are disproportionately affected by climate change. “When someone says, ‘climate science is settled,’ remind them to check the facts.” James Renwick Professor, Victoria University of Wellington: The basic radiation physics has been well known for 150 years. The details will always be under discussion, but we are already seeing very clearly the expected patterns of climate change. Lauren Simkins Assistant Professor, University of Virginia: This statement highlights the major problem with this article. The authors do not support their claims with scientific references and data. Their logic is flawed and does not take into account basic scientific theories that explain, for example, the role of certain gases in causing a greenhouse effect and the negative impacts of high levels of greenhouse gases in the atmosphere. […] So based on this statement and the lack of scientific references in this article, readers should be prompted to disregard the majority of claims it presents.

https://science.feedback.org/review/sea-level-rise-accelerating-risk-associated-coastal-storm-surge-contrary-claim-forbes/

Inaccurate

Forbes, Roy Spencer, 2016-10-25

Sea level rise, which was occurring long before humans could be blamed, has not accelerated.

Factually wrong: The evidence from records of past climate shows that the rate of sea level rise is greater now than it was before the Industrial Revolution. Misleading: The rate of sea level rise is expected to increase as a result of ocean warming and melting glacial ice, so using the current rate to project the future risk of storm surge fails to account for what the risk really is.

Continuing warming causes an accelerating rise of sea level, impacting coastal regions in a variety of ways—including increasing the damage from storm surge events.

Sea level rise, which was occurring long before humans could be blamed, has not accelerated and still amounts to only 1 inch every ten years. If a major hurricane is approaching with a predicted storm surge of 10-14 feet, are you really going to worry about a sea level rise of 1 inch per decade?

Benjamin Horton Professor, Earth Observatory of Singapore: Proxy analysis has clearly shown an acceleration in rate of sea-level rise. Our research* found that the rate of sea-level rise on the US Atlantic coast is greater now than at any time in the past 2,000 years. The research also shows a consistent link between global mean surface temperature and changes in sea level for the past millennium. The study shows that after relatively subtle changes in temperature and sea-level rise over the last 2,000 years, the rate of sea-level rise increased in the late 19th century. Sea-level rise contributes significantly to the frequency of flooding from hurricanes. The contribution from sea-level rise to flood height works in together with other factors such as timing of the storm relative to high tide, and the strength and direction of individual hurricanes. Sea-level rise between hurricanes raises the “baseline” water level and makes flooding more likely. We published another paper* showing that New York City can expect nine-foot floods, as intense as that produced by 2012’s Superstorm Sandy, at least four times more frequently over the next century. We report that floods as intense as Sandy’s would have occurred about once every 400 years on average under present day sea-level rise conditions, but that over the 21st century are expected to be about four times more probable (once every 100 years) due to an acceleration in the rate of sea-level rise. Kemp et al. (2011)Climate related sea-level variations over the past two millennia, Proceedings of the National Academy of Sciences Lin et al. (2016)Hurricane Sandy’s flood frequency increasing from year 1800 to 2100, Proceedings of the National Academy of SciencesPeter Gleick President Emeritus and Chief Scientist, Pacific Institute: A major storm that has a sea-level higher than it would otherwise have been without climate change will simply be more damaging. It doesn’t matter that current sea-level rise changes are slow. Sandy’s storm surge hit at high tide—a tide that was higher than it would otherwise have been because of human-caused climate change. Some estimates are that damages were many billions of dollars higher as a result.Kerry Emanuel Professor of Atmospheric Science, MIT: Sea level rise is indeed accelerating and is currently tracking predictions that are consistent with a roughly 1 meter (3 foot) rise by the end of the century. We are already seeing bad effects in places like Miami Beach. And 1 meter makes a large difference, so if one is concerned about one’s descendants, then yes, it is something to worry about.Jim Kossin Research Scientist, NOAA's Center for Weather and Climate: Sea level rise and its impacts vary considerably by region. To state a global mean number is misleading and irrelevant to those regions that are most vulnerable. With or without hurricanes added to the mix, the impacts on humans from sea level rise can be seen now. The author’s comparison of hurricane storm surge to sea level rise is very misleading and blurs the relevance of sea level rise to humans. Sea level rise is creating nuisance flooding in a number of places. The fact that hurricane storm surge is bigger is irrelevant and does not change the fact that people are being impacted.Victor Venema Scientist, University of Bonn, Germany: Sea level rise started before we had good instrumental observations, which makes it harder to see the acceleration. If you look sea level rise for longer periods based on indirect (proxy) evidence, it is clear that the current sea level rise is much faster than it was during the last 1000 years. See for example this article on RealClimate on a recent study for the last 2000 years. It will depend on our actions whether sea level rise will accelerate much more. See this article on the expected sea level rise for the coming century. Figure – Past and future sea-level rise. For the past, proxy data are shown in light purple and tide gauge data in blue. For the future, the IPCC projections for very high emissions (red, RCP8.5 scenario) and very low emissions (blue, RCP2.6 scenario) are shown. Source: IPCC AR5 Fig. 13.27 https://www.sharethefacts.co/share/3583ab0c-6cbe-4171-bd7a-ab2925e29e22

https://science.feedback.org/review/hillary-clinton-boards-climate-crisis-train-nowhere-roy-spencer-forbes/

-1.8

Forbes, by Roy Spencer, on 2016-10-25.

"Hillary Clinton Boards The Climate Crisis Train To Nowhere"

This commentary by Dr. Roy Spencer published in the opinion section of Forbes makes a number of inaccurate and misleading scientific claims. For instance the article claims that climate change would be so slow that “it cannot be observed by anyone in their lifetime”, which is demonstrably wrong. It also misrepresents the impacts of climate change and makes claims about sea level and temperature records that are not supported by the evidence. Note: This article was evaluated only for scientific accuracy—Climate Feedback does not endorse or oppose political opinions.See all the scientists’ annotations in context If the link does not work due to the landing page ads on Forbes, install the Hypothesis extension in your browser and switch it on from the article page.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Kerry Emanuel Professor of Atmospheric Science, MIT: The article is inaccurate in several places and conveys that one must choose between solving immediate problems, such as poverty, and long-term risks such as climate change. We can do both, and indeed must do both if we take poverty seriously, since climate change disproportionately affects the poor. Jim Kossin Research Scientist, NOAA's Center for Weather and Climate: The author makes a number of statements that are not supported by the science or by established scientific process. He is basically playing by a different set of rules than the scientific community at large, which allows him to say anything he wants in order to make his case. A number of statements are misleading and some are obfuscating, particularly in terms of potential impacts of climate change on humans. Victor Venema Scientist, University of Bonn, Germany: This article by Roy Spencer is misleading when it comes to his own work on tropospheric temperature changes and several times severely wrong outside of his expertise. It does not give a fair overview of the state of the science. Peter Gleick President Emeritus and Chief Scientist, Pacific Institute: Almost every claim in this article is scientifically inaccurate or misleading. Alexis Berg Research Associate, Harvard University: This articles uses a number of misleading statements, logical flaws and unsubstantiated claims to try to defend the erroneous idea that climate change is nothing to worry about, that there is nothing to do about it anyway, and that wanting to address it is all a power play by politicians. Benjamin Horton Professor, Earth Observatory of Singapore: The discussion on sea level rise is misleading. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from Roy Spencer; comments and replies are from the reviewers. 1.The influence of climate change on some types of extreme weather are still unclear (e.g. tornadoes), however the strongest hurricanes are expected to become even more intense as the climate continues to warm. “Global warming and climate change, even if it is 100% caused by humans, is so slow that it cannot be observed by anyone in their lifetime. Hurricanes, tornadoes, floods, droughts and other natural disasters have yet to show any obvious long-term change.” Jim Kossin Research Scientist, NOAA's Center for Weather and Climate: This statement is far too broad to be supportable, and is misleading in a few ways. Among the many aspects and impacts of climate change, some are evolving slowly and others more quickly (quickly enough to be detected within a 70-year human lifetime). There is a very important difference between saying “there has been no change”, versus “the data records are not long enough to formally detect a change”. For example, our present records of hurricanes do in fact show very large and statistically significant increasing trends in a number of measures since the 1800s. But we also know that the older data are of a lower quality than modern data, so we are uncertain of what part of the trends are due to the data issues and what part may be due to human influences. The scientific community has established a very strict set of rules for formally establishing whether or not a trend has been detected, and we constrain our statements within this rigid framework. The author’s statement here violates those rules and is unsupportable Alexis Berg Research Associate, Harvard University: As others have noted, this is flat out wrong. With barely 1C of global warming there are already changes in temperatures, humidity precipitation patterns, sea ice, land ice, sea level, vegetation, etc., that i) can be observed, and ii) can be attributed to human-made global warming. And certainly in the coming decades, that is, within our “lifetime”, further changes are going to be even more obvious. “Furthermore, the overall increases in such things as hurricanes and tornadoes have not materialized.” Jim Kossin Research Scientist, NOAA's Center for Weather and Climate: Again, this statement is not supported by the science. We are seeing changes. We just don’t have long enough data records to formally detect the changes and attribute them to human influence. The rules of detection and attribution are well established, strict, and conservative. The author’s statement here is outside of the rules and can’t be supported in any true formal scientific sense. […] It’s wrong and unsupportable to say that there have been no changes. Our theory of hurricanes and our best numerical models inform us that hurricanes will become stronger as the world warms, and that the increase will be most evident in the strongest hurricanes. These are the hurricanes that kill the most people and do the most damage. Furthermore, increases in strength or number are not the only ways that hurricanes can change. There is mounting evidence that tropical cyclones in various regions of the world are migrating poleward. This creates significant changes in hazard exposure and human mortality risk, even in the absence of any changes in strength. “Drought in the western U.S. pales in comparison to the mega-droughts tree rings tell us existed in centuries past.” Peter Gleick President Emeritus and Chief Scientist, Pacific Institute: There are many scientific papers, going back years now, that show the influence of climate changes on the western US droughts. The fact that there have been “mega-droughts” in the past is irrelevant to whether climate changes are now influencing current droughts. See: Swain et al. (2014) The Extraordinary California drought of 2013/2014: Character, Context, and the role of climate change, Bulletin of the American Meteorological Society Mann and Gleick (2015) Climate change and California drought in the 21st century, Proceedings of the National Academy of SciencesDaniel Swain Climate Scientist, University of California, Los Angeles: In Swain et al. (2014)*, we do find that global warming has increased the likelihood of one of the “ingredients” of the California drought—specifically, very high middle atmospheric pressures. A more direct reference might be Diffenbaugh et al. (2015)*, where we specifically quantify the degree to which human caused warming has increased the likelihood of drought in California. There are other papers, as well, that find at least a fractional contribution of warming to this event. I also agree with Peter Gleick’s remark that the existence of past droughts of large magnitude is largely irrelevant when seeking causes of the present one, and does not disprove a human role in modern droughts. Swain et al. (2014) The Extraordinary California Drought of 2013/2014: Character, Context, and the Role of Climate Change, Bulletin of the American Meteorological Society Diffenbaugh et al. (2015)Anthropogenic warming has increased drought risk in California, Proceedings of the National Academy of Sciences Alexis Berg Research Associate, Harvard University: Note the comparing reconstructions of past droughts with climate model projections suggests that “future drought risk will likely exceed even the driest centuries of the Medieval Climate Anomaly (1100–1300 CE) in both moderate (RCP 4.5) and high (RCP 8.5) future emissions scenarios, leading to unprecedented drought conditions during the last millennium”. See Cook et al. (2015) Unprecedented 21st century drought risk in the American Southwest and Central Plains, Sciences Advances. “Lake-bottom sediments in Florida tell us that recent major hurricane activity in the Gulf of Mexico has been less frequent than in centuries past.” Kerry Emanuel Professor of Atmospheric Science, MIT: The lake-bottom sediment study, in which I participated, catalogued hurricanes at a particular location over several thousand years. There are indeed centennial-scale variations at particular locations that are not strongly correlated across different locations, so the authors interpreted these fluctuations in terms of changing [hurricane] tracks. The technique cannot distinguish between a weak event nearby and a strong one at a distance, so there is little data pertaining to storm intensity. “It has now, even after Hurricane Matthew, been over 4,000 days since a major hurricane (Category 3 or stronger) has made landfall in the U.S.” Jim Kossin Research Scientist, NOAA's Center for Weather and Climate: The definition of US major hurricane landfall is strict but also arbitrary, and isn’t a particularly good measure of coastal risk. The threshold of a major hurricane, and the restriction that the center of a hurricane must move over land is somewhat ad hoc and may obfuscate the points of relevance. For example, many coastal communities have experienced major hurricane landfalls over the past 4,000 days. They just don’t happen to be within the geopolitical border of the contiguous US. Matthew is in fact a good example for why the author’s statement is misleading. Matthew did a great deal of damage as a major hurricane without technically having its center touch land. The fact that it didn’t make formal landfall as a major hurricane is not particularly relevant when considering coastal hazard exposure and human mortality risk. Kerry Emanuel Professor of Atmospheric Science, MIT: One can always cherry-pick a sufficiently narrow statistic, like major landfalling continental US hurricane, that will support one’s prejudice. The fact is that there has been no pause in ALL Atlantic basin or landfalling (including regions outside the US) storms. 2.Continuing warming causes an accelerating rise of sea level, impacting coastal regions in a variety of ways—including increasing the damage from storm surge events. “Sea level rise, which was occurring long before humans could be blamed, has not accelerated and still amounts to only 1 inch every ten years. If a major hurricane is approaching with a predicted storm surge of 10-14 feet, are you really going to worry about a sea level rise of 1 inch per decade?” Benjamin Horton Professor, Earth Observatory of Singapore: Proxy analysis has clearly shown an acceleration in rate of sea-level rise. Our research* found that the rate of sea-level rise on the US Atlantic coast is greater now than at any time in the past 2,000 years. The research also shows a consistent link between global mean surface temperature and changes in sea level for the past millennium. The study shows that after relatively subtle changes in temperature and sea-level rise over the last 2,000 years, the rate of sea-level rise increased in the late 19th century. Sea-level rise contributes significantly to the frequency of flooding from hurricanes. The contribution from sea-level rise to flood height works in together with other factors such as timing of the storm relative to high tide, and the strength and direction of individual hurricanes. Sea-level rise between hurricanes raises the “baseline” water level and makes flooding more likely. We published another paper* showing that New York City can expect nine-foot floods, as intense as that produced by 2012’s Superstorm Sandy, at least four times more frequently over the next century. We report that floods as intense as Sandy’s would have occurred about once every 400 years on average under present day sea-level rise conditions, but that over the 21st century are expected to be about four times more probable (once every 100 years) due to an acceleration in the rate of sea-level rise. Kemp et al. (2011)Climate related sea-level variations over the past two millennia, Proceedings of the National Academy of Sciences Lin et al. (2016)Hurricane Sandy’s flood frequency increasing from year 1800 to 2100, Proceedings of the National Academy of Sciences Peter Gleick President Emeritus and Chief Scientist, Pacific Institute: A major storm that has a sea-level higher than it would otherwise have been without climate change will simply be more damaging. It doesn’t matter that current sea-level rise changes are slow. Sandy’s storm surge hit at high tide—a tide that was higher than it would otherwise have been because of human-caused climate change. Some estimates are that damages were many billions of dollars higher as a result. Kerry Emanuel Professor of Atmospheric Science, MIT: Sea level rise is indeed accelerating and is currently tracking predictions that are consistent with a roughly 1 meter (3 foot) rise by the end of the century. We are already seeing bad effects in places like Miami Beach. And 1 meter makes a large difference, so if one is concerned about one’s descendants, then yes, it is something to worry about. Jim Kossin Research Scientist, NOAA's Center for Weather and Climate: Sea level rise and its impacts vary considerably by region. To state a global mean number is misleading and irrelevant to those regions that are most vulnerable. With or without hurricanes added to the mix, the impacts on humans from sea level rise can be seen now. The author’s comparison of hurricane storm surge to sea level rise is very misleading and blurs the relevance of sea level rise to humans. Sea level rise is creating nuisance flooding in a number of places. The fact that hurricane storm surge is bigger is irrelevant and does not change the fact that people are being impacted. Victor Venema Scientist, University of Bonn, Germany: Sea level rise started before we had good instrumental observations, which makes it harder to see the acceleration. If you look sea level rise for longer periods based on indirect (proxy) evidence, it is clear that the current sea level rise is much faster than it was during the last 1000 years. See for example this article on RealClimate on a recent study for the last 2000 years. It will depend on our actions whether sea level rise will accelerate much more. See this article on the expected sea level rise for the coming century. Figure – Past and future sea-level rise. For the past, proxy data are shown in light purple and tide gauge data in blue. For the future, the IPCC projections for very high emissions (red, RCP8.5 scenario) and very low emissions (blue, RCP2.6 scenario) are shown. Source: IPCC AR5 Fig. 13.27 “If Hillary would have fact-checked her example of sea level rise in Norfolk, Virginia, she would have found out that the experts already know this is mostly due to the land there sinking.” Benjamin Horton Professor, Earth Observatory of Singapore: Without global warming, global sea level would have risen by less than half the observed 20th century increase and might even have fallen. We published another paper in PNAS (Kopp et al., 2016*) that showed that with global warming global sea level rose by about 14 centimeters, or 5.5 inches, from 1900 to 2000. That is a substantial increase, especially for vulnerable, low-lying coastal areas. The sinking of land in Virginia is responsible for the slow sea-level rise from 3000 years ago to the beginning of the industrial revolution. The 20th century rise was extraordinary in the context of the last three millennia—and the rise over the last two decades has been even faster. The study’s global sea-level reconstruction calculated how temperatures relate to the rate of sea-level change. Based on this relationship, the study found that, without global warming, 20th century global sea-level change would very likely have been between a decrease of 3 centimeters (1.2 inches) and a rise of 7 centimeters (2.8 inches). A companion report finds that, without the global warming-induced component of sea-level rise, more than half of the 8,000 coastal nuisance floods observed at studied US tide gauge sites since 1950 would not have occurred. Kopp et al. (2016)Temperature-driven global sea-level variability in the Common Era, Proceedings of the National Academy of Sciences 3.If followed, the pledged greenhouse gas emissions reductions of the international Paris Agreement will significantly reduce future warming and its impacts. “[…]even if the countries of the world agree to do what they promised on climate change, […]the promised actions will have no measurable effect on future global temperatures.” Victor Venema Scientist, University of Bonn, Germany: The current promises of governments around the world (INDCs) are not enough to stay below a warming of 2 °C, but they do make a difference. In an article in Nature this June, Joeri Rogelj and colleagues: “The INDCs collectively lower greenhouse gas emissions compared to where current policies stand, but still imply a median warming of 2.6–3.1 degrees Celsius by 2100.” “[…]until we develop a practical, cost-competitive alternative to fossil fuels, it is unlikely that renewable energy will ever make up more than 15-20% of global energy requirements.” Celine Guivarch Senior researcher, CIRED, Ecole des Ponts: In many countries renewables are already competitive compared to fossil fuels, and represent a larger share than the 15-20% mentioned here. Costs of renewable are still falling. And the investment in renewable is accelerating. For instance, the IEA has revised its renewable forecasts upwards. Many scenarios and studies foresee that renewables could represent a much larger share than 15-20%. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: Dr. Spencer provides no evidence to back up his assertion that renewables are necessarily limited to 15%-20% of generation. Prices of renewable technologies have been falling rapidly over the past decade, with solar power alone falling 60% and wind falling 40%. In more and more parts of the world renewables are cost-competitive with traditional fossil fuels. And unlike traditional fuels, renewables are not mature technologies and likely have additional price reductions to come. In some areas additional storage might be needed to balance out high renewable penetration. Even here storage costs have fallen dramatically due to advances in battery technologies. Additionally, electric vehicles and natural gas both enable additional renewables through grid balancing. “And since the biggest risk to humanity is poverty, if we allow policymakers to have their way, the resulting energy poverty will indeed cause the deaths of some of our children and grandchildren.” Celine Guivarch Senior researcher, CIRED, Ecole des Ponts: Poverty and energy poverty are indeed a risk for humanity; but current understanding shows that unmitigated climate change would hinder the efforts of poverty alleviation, because climate change impacts bear on most vulnerable countries and people. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: There is no necessary tradeoff between fighting poverty and climate change. There are actually a number of co-benefits to a more sustainable development pathway. For example, outdoor air pollution driven largely by coal use currently kills well over a million people annually*, and represents one of the most urgent public health crises on the planet. Addressing it by transitioning from coal to renewables, nuclear, and natural gas could benefit both health and the environment in developing countries. Rohde (2015)Air Pollution in China: Mapping of Concentrations and Sources, PLOS ONE Note: Satellites have measured the Earth’s temperature for only about 30 years. When comparing models to observations, it is wise to include the wealth of longer-term measurements in order to avoid being mislead by short-term natural fluctuation. “But the observed warming as monitored by satellites (our only truly global monitoring system) has been only about half of what computerized climate models say should be happening.” Carl Mears Senior Research Scientist, Remote Sensing Systems (RSS): The statement is fairly accurate but leaves the inference of causes up to the reader. A recent paper by Santer et al. (2016)* investigated this issue in considerable detail. For middle tropospheric temperatures the paper found that, on average, models showed 1.71 times more warming than the mean of the most recent version of the satellite data for the 1979-2015 period. This is for near global mean temperatures. For the lower troposphere, the models show about 2 times more warming than the satellites. Note that the Remote Sensing Systems lower tropospheric dataset has not yet been upgraded to the latest version, which is likely to show more warming. The article does not discuss possible reasons for this discrepancy, but given the tone of the rest of the article, the reader is expected to use the trend differences as evidence that long-term projections by climate models are suspect. These ratios do not provide such evidence. At least part of the discrepancy is known to be caused by errors in the forcings used to drive the CMIP-5 climate models. After the year 2000, the CMIP-5 models were driven by forecast values for important parameters such as volcanic aerosols, solar output, and stratospheric ozone. The forecasts turned out to be slightly inaccurate, causing the models to predict more warming than they would have if the correct forcings had been used. (Of course, these correct forcings were in the future and thus unknowable at the time the model computations were performed). Other possible causes include natural variability in the real world (which might produce a period of reduced warming) and errors in the model physics. Only errors in the model physics would cause long-term global warming to be overestimated, and there is no significant evidence that supports large errors in the model physics. Over a much longer time period, 1880-present, the warming at the surface agrees well with that expected by the CMIP-5 models. The longer time period is important because the effects of random fluctuations due to natural variability tend to average away as the time period considered gets longer. Santer et al. (2016)Comparing tropospheric warming In climate models and satellite data, Journal of Climate

https://science.feedback.org/review/sea-level-rise-those-non-disappearing-pacific-islands-bjorn-lomborg-wall-street-journal/

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The Wall Street Journal, by Bjorn Lomborg, on 2016-10-13.

"About Those Non-Disappearing Pacific Islands"

This Wall Street Journal article comments on the fact that atoll islands in the Pacific are not all simply shrinking as sea level rises, because dynamic coastal processes can move sediment to build shorelines outward. However, the article doesn’t mention that sea level rise related to unchecked global warming would ultimately make many low-lying islands in the Pacific uninhabitable. The author, Bjorn Lomborg, cherry-picks this specific piece of research and uses it in support of a broad argument against the value of climate policy. He also misrepresents the Paris Agreement to downplay its potential to curb future climate change. See all the scientists’ annotations in contextGUEST COMMENTS: Katrin Meissner Professor, University of New South Wales: This article is misleading. The dynamics of shorelines of low-lying Pacific Islands are complicated and influenced by many local factors. Climate change and associated sea-level change are the underlying trend that will “win” over long time scales. There are many wiggles and local anomalies that, if taken out of context and analysed over short timescales, might hide the overall trend. This article is a textbook example of cherry-picking–jumping to false conclusions based on a small sample of data that does not reflect the bigger picture. Paul Kench Professor, The University of Auckland: There are a lot of claims that islands are passive geological entities that will sit there and drown. Our work shows that they are anything but static. They are dynamic. They move around and they can grow. So just because sea level is rising, it doesn’t mean doom and gloom for all atolls. Although the islands may survive into the future, the changes could still affect issues like fresh water and agriculture, potentially making life on these islands much more difficult than it is today.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Stephan Lewandowsky Professor, University of Bristol: This article is very interesting because it exemplifies a highly-misleading rhetorical practice that is effective, frequently used, but not easily recognized by the public–and hence all the more damaging. This is known as “paltering” and the term was popularized by Frederick Schauer and Richard Zeckhauser in 2009 and refers to “fudging, twisting, shading, bending, stretching, slanting, exaggerating, distorting, whitewashing, and selective reporting.” A successful palterer will try to avoid being untruthful in each of his/her utterances, but will nonetheless put together a highly misleading picture based on selective reporting, half-truths, and errors of omission. As the commenters have pointed out, this is the case here. Unfortunately, paltering is difficult for non-experts to detect and the best defense against it is to know who engages in it and for what political purpose. Lauren Simkins Assistant Professor, University of Virginia: Land area gains due to sediment accretion in the Marshall Islands and other low-lying coastlines do not necessarily indicate that coastal populations are spared from the effects of sea-level rise. I find the presented argument that the focus should be on reducing poverty and political corruption in the Marshall Islands rather than on cutting global carbon emissions not well supported and misleading to a general audience. Alexis Berg Research Associate, Harvard University: The article contains a number of logical fallacies – red herring, false dichotomy – that seem to be recurrent in Lomborg’s articles. He does point out an interesting and perhaps little-known fact about current land dynamics of Pacific atoll islands; however, this fact, in and of itself, does not all of a sudden make current concern about global climate change overblown and irrelevant, as the article somehow implies. His presentation of the Paris Agreement and discussion of the best strategy to address global warming is, in my view, dishonest and misleading. Daniel Kammen Professor, University of California, Berkeley: In my view the author attempts to develop a polemic that funds spent on climate change are not benefiting the poor, and that there is, in fact, a choice between one and the other. This is demonstrably false, and yet the author repeats it despite the evidence. James Renwick Professor, Victoria University of Wellington: The effects of sea level rise on tropical Pacific islands are indeed complicated. Implying that climate change and sea level rise are therefore not urgent concerns is very misleading. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from Bjorn Lomborg; comments and replies are from the reviewers. 1. Sea level rise does not simply result in reduction of island area as other dynamic processes shape their coasts, but in the long term it would make low-lying islands uninhabitable. “Research shows that this process is overpowering the erosion from sea-level rise, leading to net land-area gain. This is not only true for the Marshall Islands. […]several studies have documented noteworthy shoreline progradation [growth] and positional changes of islands since the mid-20th century, resulting in a net increase in island area.” James Renwick Professor, Victoria University of Wellington: The dynamics of sand accretion and loss across the tropical Pacific is indeed complicated, and many atolls are at the moment growing. However, as sea levels rise in this area of the globe, water tables also rise and become salinated, reducing the availability of fresh water for drinking or agriculture. Focusing on the tropical Pacific takes attention away from regions where the signal is much clearer, e.g. the east coast of the USA. The occurrence of “nuisance flooding” and coastal inundation has risen dramatically in recent decades. Another 50-100 centimeters of sea level rise globally threatens vast swaths of built infrastructure and hundreds of millions of lives. Whether or not Pacific atolls accrete or shrink is not the most central issue. Katrin Meissner Professor, University of New South Wales: This statement is oversimplified and cannot be generalised. For example, there is evidence from the Solomon Islands that five islands have disappeared in recent years while six others have experienced severe shoreline recession*. This evidence is based on time series of aerial and satellite imagery from 1947 to 2014 of 33 islands, along with historical insight from local knowledge: “Shoreline recession at two sites has destroyed villages that have existed since at least 1935, leading to community relocations…” Albert S et al (2016) Interactions between sea-level rise and wave exposure on reef island dynamics in the Solomon Islands Environmental Research Letters Lauren Simkins Assistant Professor, University of Virginia: As wave energy and rising sea levels batter coastlines, the erosional products (i.e. sediments) can either be accreted onto the existing land or removed offshore into the deep ocean. Where the sediment is redistributed depends on a number of factors. Although sediment accretion can increase land area, it does little to change the elevation of low-lying islands, like the Marshall Islands. Therefore, people living in low-lying areas, even if there is historical land area gain, are still susceptible to inundation and damages due to storm waves, higher-than-usual tides (e.g. king tides), and sea level rise. These unconsolidated, loose sediments are also easily mobilized; therefore, localized land area gains by sediment accretion can be very dynamic on short timescales. This article could leave readers thinking that land area gains alone can mitigate the effects of sea level rise on low-lying coastal areas, but land elevation is what is really important. “The most famous of these studies, published in 2010 by Paul Kench and Arthur Webb of the South Pacific Applied Geoscience Commission in Fiji, showed that of 27 Pacific islands, 14% lost area. Yet 43% gained area, with the rest remaining stable.” Paul Kench Professor, The University of Auckland: This comment does provide a reasonable assessment of the message of our article: that the majority of islands have become larger or remained stable and that islands are locationally dynamic on their reef platforms. We think these dynamic features do pose management challenges for island communities. However, all reports fail to reflect the nuances of our work. Arthur Webb Coastal geomorphologist, The University of Wollongong: What is for sure is that the island’s natural sedimentary systems will not just sit and be unresponsive. The islands will respond but we must be very careful to point out that ”response” does not necessarily mean that the islands will be maintained in the form we recognize today, that is, we do not know how long an island with soils for agriculture, complex vegetation, good fresh groundwater reserves, etc. can be maintained. Indeed, given what we understand of increasing rates of sea level rise we may be talking about relatively inhospitable gravel banks as the response to the next 100 years of sea level rise. “It seems self-evident that rising sea levels will reduce land area. However, there is a process of accretion, where coral broken up by the waves washes up on these low-lying islands as sand, counteracting the reduction in land mass. Research shows that this process is overpowering the erosion from sea-level rise, leading to net land-area gain.” Arthur Webb Coastal geomorphologist, The University of Wollongong: It’s just plain wrong to assume that all atolls are washing away. It’s also wrong to sugar-coat the sobering facts that rising sea levels will ultimately seal the fate of low-lying islands and their limited soils and groundwater. The confusion isn’t surprising. It’s just more complicated than many expect. 2. The author reaches his conclusion by relying on flawed reasoning: for instance he cherry-picks studies and ignores the “big picture”, in contradiction to what he recommends. “suggest that residents are fleeing atolls swiftly sinking into the sea. Yet new research shows that this is not the entire—or even an accurate—picture.”Emmanuel M Vincent Research Scientist, University of California, Merced: Scientists’ comments on this article clearly show that it is also not an “entire” or “accurate” picture. So Mr. Lomborg is using the very flawed reasoning he is condemning others of. “Representatives from the Marshall Islands have been vocal about the need for strong global action on climate. President Hilda Heine has told reporters that longtime residents are leaving the Marshall Islands because climate change is threatening the nation’s existence.” Daniel Kammen Professor, University of California, Berkeley: Mr. Lomborg cherry-picks studies relative to the global average. (Indeed, some areas of the Canadian Maritimes and Greenland are expected to see sea-level fall, but overall the rise is significant and a huge danger to the poor). The idea that aiding the poor was an alternate to addressing climate change was wrong 15 years ago when I last debated Mr. Lomborg and is wrong today. False dichotomies are a sad refuge from the facts of both poverty and climate change. Emmanuel M Vincent Research Scientist, University of California, Merced: This is an interesting rhetorical trick by Bjorn Lomborg. So far he has only supported the point that ‘as of today, the area of many Pacific islands have not decreased’. But this doesn’t mean that ‘the islands existence is not threatened’, notably in the future as sea level rise becomes more severe. So here, he is swapping a weak claim that he has supported for a much stronger one that he has not, a version of the red herring fallacy. “Those who seek to help should keep the bigger picture in mind.” James Renwick Professor, Victoria University of Wellington: Exactly Mr Lomborg. That’s why focusing on a small component of the story, in an area where many competing forces mask the underlying signal, is such a narrow approach. If one looks at the big picture of climate change, the loss of ice and snow, the increasing high temperature extremes, the already-apparent effects of sea level rise around the globe, the urgency of the problem becomes crystal-clear. “Policy makers who want to help the residents of the Marshall Islands today should look at improving the islands’ resilience” Alexis Berg Research Associate, Harvard University: This is a classic technique in Lomborg’s articles: he focuses on one small aspect of climate change – here the Marshall Islands, other times maybe polar bears or heat-related human deaths – that i) he passes off as the main concern about global warming, and ii) that he can provide some seemingly contradictory information about… All the other consequences of global warming are conveniently set aside… Red herring. 3. Reducing greenhouse gas emissions to meet Paris Agreement pledges will cost money, but will also have a significant impact on the severity of global warming this century, contrary to Lomborg’s claim. “This will achieve almost nothing. My peer-reviewed research, published last November in the journal Global Policy, shows that even if every nation were to fulfill all their carbon-cutting promises by 2030 and stick to them all the way through the century—at a cost of more than $100 trillion in lost GDP—global temperature rise would be reduced by a tiny 0.3°F (0.17°C).”John Sterman Professor, Massachusetts Institute of Technology: Dr. Lomborg sets out to show that the INDCs [emission reduction pledges] are useless. To do so he grossly misrepresents the pledges. He constructs an incomplete accounting that omits the pledges of many nations, ignores China’s pledge to cap its emissions by 2030, and assumes that the [European Union countries] will abandon their commitment to emissions reductions as soon as their pledges are fulfilled. (find more details in this rebuttal of Lomborg’s paper) James Renwick Professor, Victoria University of Wellington: The last IPCC report makes it very clear that following a path of strong emissions reductions can indeed cap warming at 2C or less, while business as usual would see 4-5C of warming this century. It is also now clear that meeting the Paris targets will likely save the West Antarctic ice sheet from melting, while other scenarios would see many metres of sea level rise, effectively destroying many of the major cities of the world. The costs of such inaction are almost incalculable. “At a cost of between $1 trillion and $2 trillion annually, the Paris climate agreement, recently ratified by China, is likely to be history’s most expensive treaty. It will slow the world’s economic growth to force a shift to inefficient green energy sources.” Alexis Berg Research Associate, Harvard University: Not sure how these costs are derived—references would be good. […] These treaty costs may appear unprecedented, but so are the risks posed by climate change. Climate change “costs” are hard to quantify precisely – for instance, how to give a monetary value to the loss of certain ecosystems?—but likely to be quite significant. This recent study in Nature, for instance, indicates that: “If future adaptation mimics past adaptation, unmitigated warming is expected to reshape the global economy by reducing average global incomes roughly 23% by 2100 and widening global income inequality, relative to scenarios without climate change”. Burke et al (2015) Global non-linear effect of temperature on economic production. Nature Gary Yohe Professor of Economics and Environmental Studies, Wesleyan University: There are hundreds of corporations who have signed on to reducing emissions in their own best interest (e.g. Walmart, DuPont, Chevron, Johnson and Johnson, Mercedes Benz, Dow… consult the White House website for an expanded list), reducing emissions and helping their customers do the same, for the benefit of their bottom line and their employees and their shareholders. These companies know that they will make money working to reduce their carbon emissions (being first to get there). Their gains are not recognized by Bjorn’s cost estimates. This is not to say that it is free. It is to say that Bjorn’s Holy Grail of cost-benefit analysis should include the enormous deductions to costs from the market.

https://science.feedback.org/review/james-lovelock-interview-by-end-of-century-robots-will-have-taken-over-decca-aitkenhead-the-guardian/

-1.4

The Guardian, by Decca Aitkenhead, James Lovelock, on 2016-09-30.

"James Lovelock: ‘Before the end this century, robots will have taken over’"

The Guardian interviewed James Lovelock (who is promoting a new book) about his speculations on Earth’s future. While the article largely features Lovelock’s subjective opinions about the future, it also contains statements about climate science and climate change that reviewers find inaccurate and unsupported by current science. The article does not inform the reader when Lovelock’s opinions and extraordinary claims are at odds with the conclusions of science that are based on a wealth of empirical data.See all the scientists’ annotations in contextGUEST COMMENTS: Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: It is hard to evaluate this article, as it’s an interview rather than any specific statement of fact by the author. However, the interviewee James Lovelock makes a number of misleading, unsupported, or outright incorrect statements about climate science which largely go unchallenged. While the article presumably faithfully reports Lovelock’s opinions, when those opinions are couched as scientific statements more pushback (or at least nuance) might be warranted.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. James Renwick Professor, Victoria University of Wellington: Some interesting ideas, but this is largely a flight of fancy, not grounded in the science of climate change. Aimée Slangen Researcher, Royal Netherlands Institute for Sea Research (NIOZ): The quotes on climate change (e.g. sea-level rise, CO2 emissions) do not reflect the current state of the scientific literature at all. Ken Caldeira Senior Scientist, Carnegie Institution for Science: Jim Lovelock is a creative and original thinker who has had many great ideas and who has made many important contributions over his career. Creative people have great ideas by having many ideas and then filtering out the ideas that are not so great. Many very creative people are better at the idea generation stage than the idea filtering stage. The journalist did not balance Lovelock’s statements with a set of clear statements saying that the vast majority of informed climate scientists (as, for example, represented by the IPCC reports) have reached consensus on conclusions that are diametrically opposed to what Lovelock is saying, and that the IPCC scientists have backed up their statements with a wealth of empirical data, whereas Lovelock is largely opining without providing any substantive evidence to support his rather extraordinary claims. Extraordinary claims demand extraordinary evidence, and Lovelock has not even come up to the standards of providing what the scientific community would consider to be ordinary evidence. Lauren Simkins Assistant Professor, University of Virginia: Inaccuracies and a lack of reference to scientific findings result in an article that is purely opinion-based and extremely misleading. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from James Lovelock; comments and replies are from the reviewers. 1.Climate models used by scientists have overall accurately projected the change of climate observed over the past 20 years, notably regarding global temperature and CO2 concentration. ” ‘CO2 is going up, but nowhere near as fast as they thought it would. The computer models just weren’t reliable.’ ” Ken Caldeira Senior Scientist, Carnegie Institution for Science: This statement is just plain wrong. Atmospheric CO2 content has recently surpassed 400 ppm and this rate of increase is in line with model projections. Aimée Slangen Researcher, Royal Netherlands Institute for Sea Research (NIOZ): This graph from the IPCC’s Summary: For Policymakers shows that CO2 is actually at the medium to higher end of the projected changes:Figure: Global mean surface temperature as a function of cumulative total global CO2 emissions from multi-model results for various emissions scenarios (coloured lines) and observations (black line). Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: Lovelock seems rather confused on this point. CO2 has actually gone up a bit faster than the Intergovernmental Panel on Climate Change (IPCC) predicted back in the Fourth Assessment Report: But modeling CO2 concentrations isn’t really that complicated (at least in the short term), and not a big focus of the IPCC and climate modelers. Rather, they use a number of different future emission scenarios reflecting different paths society could take to estimate the future warming, sea level rise, precipitation changes, and other more complex emergent properties of the climate system. Lovelock seems to be mixing up CO2 concentrations with temperatures, but even temperatures have been well within the range projected by models. ” ‘Anyone who tries to predict more than five to 10 years is a bit of an idiot, because so many things can change unexpectedly.’ ” Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: Actually, scientists have a reasonably good track record at predicting changes to the Earth’s climate so far. For example, in 1981 NASA scientist James Hansen and colleagues predicted that continuing CO2 emissions would warm the earth 0.4 °C by 2010. In reality, 2010 temperatures were about 0.5 °C warmer than in the early 1980s. Similarly, our climate models generally do a good job of reproducing the range of temperature change (and variability) seen in observational data: ” ‘and it’s only got to take one sizable volcano to erupt and all the models, everything else, is right off the board’ ” Aimée Slangen Researcher, Royal Netherlands Institute for Sea Research (NIOZ): Volcanic eruptions do have a cooling effect, but the effect is temporary (the aerosol has a lifetime of about a year, with a recovery period of up to a decade), so you’d need a Pinatubo to go off every couple of years (which is not too likely to happen) and that would still not be enough to counteract the climate response to the increase in CO2 emissions. There is a lot of literature looking at the effect of volcanic eruptions in climate models*, whichshows the impact on sea-level rise, which is a small temporary sea-level fall, followed by a recovery over a decade or so. Gleckler et al (2006) Krakatoa lives: The effect of volcanic eruptions on ocean heat content and thermal expansion, Geophysical Research Letters Gregory (2010) Long‐term effect of volcanic forcing on ocean heat content, Geophysical Research LettersZeke Hausfather Director of Climate and Energy, The Breakthrough Institute: Volcanoes have a sizable impact on the climate, but a relatively short-lived one. The impact of a large volcano like the Pinatubo eruption in 1991 will cool the climate for a few years, but after five years or so the system would revert to nearly the same state it would have been without the eruption*. It would take a supervolcano or a large period of extended volcanism to seriously disrupt our modeled scenarios, and these sort of events are relatively rare (the odds of them happening in the next 100 years are very small). Some climate models do actually have volcanoes of various sizes stuck in randomly in the future (since we can’t really predict future volcanism apart from assuming it occurs at roughly the same rate as we’ve experienced in the past), but the inclusion of these don’t really change the expected warming or other climate impacts in the next century. Hansen et al (1996) A Pinatubo Climate Modeling InvestigationJames Renwick Professor, Victoria University of Wellington: This is completely untrue. In terms of CO2 emissions, all the volcanic eruptions in the world combined put less than 1% of human CO2 emissions into the atmosphere every year. A large volcanic eruption in the tropics can cool the climate significantly for a couple of years (such as Mt Pinatubo in 1991) but climate models capture this extremely well. 2. There are a variety of energy technologies that could help reduce greenhouse gas emissions, and each has strengths and weaknesses. “Even more heretical than his enthusiasm for fracking is Lovelock’s passionate support for nuclear power.” Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: Here Lovelock is less heretical than he thinks; most future energy scenarios that meet aggressive climate goals show an expansion of nuclear energy, particularly in countries like China. There is something of an open question whether Nuclear will remain cost-competitive with other near-zero carbon technologies, however, given how quickly the costs of these technologies have fallen: Source: energy.gov ” ‘Let’s see … I think uranium that is affordable to extract would last about 50 years, something in that range. It might be 100. When you’ve used all that up, you go to thorium, and that would last you three times as long as uranium—so, shall we say, about 200 years?’” Ken Caldeira Senior Scientist, Carnegie Institution for Science: It is true that conventional uranium resources are insufficient to power civilization for the long-term. However, innovative approaches are making uranium extraction from seawater look increasingly attractive economically. Cost-effective uranium extraction from seawater could power civilization for a very long time. That said, the Sun will also last a very long time, so solar power also makes a lot of sense, especially if we could develop good energy storage or global-scale electricity grids that could wheel power to the night side of the Earth. ” ‘You see, gas in America is incredibly cheap, because of fracking,’ he says. But what about the risk of triggering earthquakes? He rolls his eyes.” Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: Lovelock is correct that hydraulic fracturing has played a large role in driving down U.S. natural gas prices. He also states a reasonable position that some of the opposition to “fracking” has been based on scientifically-dubious claims. That said, there are certainly best practices that the industry could apply to minimize drinking water contamination as well as seismic activity (which is primarily associated with wastewater disposal wells rather than fracturing per se). Where fracking gets more complicated is in its climate impact. While we are very likely better off if we are replacing coal with gas, it’s hard to make the case that a large buildup of gas infrastructure is consistent with meeting our aggressive climate goals, at least in developed countries like the United States. For more details, see this recent Yale Climate Connections article. Lauren Simkins Assistant Professor, University of Virginia: There is a big misconception about the trigger of recent earthquakes in Oklahoma. Fracking in the United States has been used for several decades. However, the disposal of waste water into the subsurface has been directly linked to the recent earthquakes in Oklahoma. A quick google scholar search on “Oklahoma earthquakes”will bring up numerous articles that demonstrate this point. My family has lived in Oklahoma for decades and I can tell you first-hand that the increase in number of >3.0 magnitude earthquakes is unprecedented in the past 8 years. 3. The article contains some exaggerated assertions, as well as imaginative speculation about the future of human civilization—some of which simply reflects the author’s opinion and is at odds with scientific results that are based on evidence and data. ” ‘You’ve only got to look at Singapore. It’s two-and-a-half times higher than the worst-case scenario for climate change, and it’s one of the most desirable cities in the world to live in.’” Aimée Slangen Researcher, Royal Netherlands Institute for Sea Research (NIOZ): There is a study by Cannaby and colleagues from the UK Met Office on sea-level rise around Singapore*. They talk about vulnerable regions within 2 m of the sea level, and find a ‘worst-case’ sea-level rise of 0.74 ± 0.29 m by 2100, so I’d say this statement is not correct. Cannaby et al (2016) Projected sea level rise and changes in extreme storm surge and wave events during the 21st century in the region of Singapore, Ocean ScienceKen Caldeira Senior Scientist, Carnegie Institution for Science: I am not sure I understand Lovelock’s point about Singapore. Singapore is a relatively wealthy, urbanized country, with an economy that is not highly weather dependent. One would expect Singapore to be able to adapt to temperature changes with far greater ease than would a poor agrarian economy. Also, several studies have projected massive increases in sea-level as a consequence of climate change. Most of Singapore is within 15 meters of sea-level. Thus, if CO2 emissions continue, we can expect most of Singapore to be underwater within a few centuries. Lauren Simkins Assistant Professor, University of Virginia: Desirability of a location has nothing to do with how safe it is from the effects of climate change. “His Gaia hypothesis, which contends that the earth is a single, self-regulating organism, is now accepted as the founding principle of most climate science […]” James Renwick Professor, Victoria University of Wellington: This is going a bit far. The Gaia gave many scientists food for thought, and a new way of thinking about the climate system in a holistic way, but it is hardly the “founding principle” of most climate science. That remains the physics of fluid flow and heat transport, plus chemistry and biology, etc. Lauren Simkins Assistant Professor, University of Virginia: Climate science is based on physical, biological, and chemical processes. There are feedbacks between these processes such as biological consumption of atmospheric CO2 by photosynthesis. However, the idea of a self-regulated Earth system due to biological activity is not a common principle of climate science. “Before the end of this century, 80% of the world’s population would be wiped out.” Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: The late Stephen Schneider, one of the giants of modern climate science, once said that in his opinion “the ‘end of the world’ and ‘good for you’ are the two lowest probability outcomes” when discussing climate change. Lovelock seems to be swapping from one extreme largely unsupported by the bulk of existing scientific evidence to the opposite. In reality, our best evidence suggests that unmitigated climate change would be very detrimental to society (and the natural world), but that we can address it through difficult concerted action. The worst potential outcomes of climate change occur in scenarios where CO2 triples relative to pre-industrial levels, and while we still have a long way to go, the actions that countries around the world committed to in Paris will help avoid some of the most disastrous outcomes. ” ‘Well, [the green movement is] a religion, really, you see. It’s totally unscientific.’ ” Lauren Simkins Assistant Professor, University of Virginia: The ability of greenhouse gases to trap heat in the atmosphere, the fact that loss of ice decreases how much energy is reflected from Earth’s surface back to space, and ocean acidification due to uptake of CO2 into the ocean are all scientifically explained by chemical and physical processes. I am sure there are different definitions of “the green movement”, but any action that “the green movement” can advocate for reduced greenhouse gas emissions has the potential to alter the physical, chemical, and biological processes that cause warming.

https://science.feedback.org/review/climate-exaggeration-backfiring-robert-bradley-jr-forbes/

-1.7

Forbes, by Robert Bradley Jr., on 2016-09-23.

"Climate Exaggeration is Backfiring"

While inaccurate climate alarmism should certainly be avoided, this Forbes’ article fails to demonstrate that climate science has been alarmist. According to the scientists that reviewed this article, the piece relies on false assertions, misleading representations of science and scientists, and poor sources. Because the climate system responds somewhat slowly, the extent of future impacts depends critically on current greenhouse gas emissions, which can commit us to long-lasting changes. The author fails to grasp this point when he asserts that the worst impacts of climate change should have already occurred if they were realistic. The net economic costs of climate change are likely to be significant and to increase over time. However, attempts to measure climate change economic impacts at the global scale is highly dependent on economists’ assumptions and there are a hosts of climate change impacts that cannot be accounted for by consumption-based global aggregations of economic impacts (e.g. impacts on ecosystems, more pronounced impact on developing countries…).See all the scientists’ annotations in context REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Victor Venema Scientist, University of Bonn, Germany: This picking of quotes that are convenient for Robert Bradley Jr.’s narrative while ignoring what most climate scientists say is one of the most used rhetorical tools of this piece. The other is the use of offensive emotional language to reduce the critical thinking of his readers. People should know that Forbes is nowadays just a blogging platform. Britta Voss Postdoctoral Research fellow, U.S. Geological Survey: This article contains no serious evidence to support its claims that climate science is fraudulent and climate action is pointless. All of the sources it cites either do not truly support the claims or are not valid in themselves. It provides very little information of any sort, and is mostly a collection of debunked theories, cherry-picked references to actual science, and unsubstantiated mantras. Kyle Armour Assistant Professor, University of Washington: There is very little substance to evaluate here. Yes, one can find examples of when individual scientists or politicians have exaggerated the impacts of climate change. But to present those examples as if they are mainstream views, when they are not, is very misleading. Frank Vöhringer Dr. rer. pol, Scientist, Ecole Polytechnique Fédérale de Lausanne (EPFL): The article is a polemic with many derogatory and misleading statements. Overall, it’s a piece of disinformation. The pro-fossil-fuel bias becomes most apparent at the end of the article. Jeremy Fyke Postdoctoral researcher, Los Alamos National Laboratory: On the whole, this article is not an objective critique of climate science. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from Robert Bradley Jr.; comments and replies are from the reviewers. 1. Natural variability in Earth’s climate system drives year-to-year fluctuations but the underlying long-term warming trend driven by human activities is clear. “The discrepancy between model-predicted warming and (lower) real-world observations has inspired new respect for natural climate variability relative to greenhouse-gas forcing.” Victor Venema Scientist, University of Bonn, Germany: Robert Bradley Jr. probably makes the typical mistake of equating the spread of individual model simulations within the ensemble spread with the model uncertainty. If climate models are used for decadal climate prediction, like Robert Bradley Jr. does here, the uncertainty is twice as large as the model spread. (more details and explanations) Natural variability has been studied by science since the beginning. That El Niño fluctuations can give the appearance of a “hiatus” is something scientists have warned about since the likes of Robert Bradley Jr. have started their “hiatus” meme, ignoring all those warnings. Without any need for statistical expertise, this can be seen in the plot below from the Texas State Climatologist. Source “‘Although some researchers doubted the existence of a global warming hiatus because of coverage bias, artificial inconsistency, and a change point analysis of instrumental Ts records,’ a just-published study at Nature.com’s Scientific Reports found, ‘it is now accepted that a recent warming deceleration can be clearly observed.’” Jeremy Fyke Postdoctoral researcher, Los Alamos National Laboratory: …which has been truncated by several years of record temperatures increases—on top of previous record warmth. This is the superposition of a forced trend on top of natural variability. The cherry-picking of time series to prove that the Earth isn’t warming due to anthropogenic influence is a classic climate change contrarian tactic. Emmanuel M Vincent Research Scientist, University of California, Merced: This graph of global temperature helps to put the “slowdown” of warming that occurred around the 2000-2010 period in perspective. It is misleading to put the emphasis on the slowdown without reminding that, over the long term, the temperature keeps rising. Source: NOAA Britta Voss Postdoctoral Research fellow, U.S. Geological Survey: This article in Scientific American provides context left out by the author on the scientific debate over the warming “hiatus.” By cherry-picking only this line from a single study, the author misrepresents the painstaking process of data analysis and hypothesis testing that led to that conclusion. As the Scientific American article points out, the authors of the study cited by the author were confident in reporting their findings—which do not refute the existence of anthropogenic global warming—because science exists to challenge previous work and is constantly incorporating new information that may alter previous conclusions, a fact which undercuts the author’s claims repeated throughout his article that climate science is a politically-motivated house of cards. 2. While impacts of climate change are already occurring, much greater impacts are expected to build in the future as a consequence of current and future greenhouse gas emissions. “Back in the late 1980s, the UN claimed that if global warming were not checked by 2000, rising sea levels would wash entire counties away.” Britta Voss Postdoctoral Research fellow, U.S. Geological Survey: Rising seas are, in fact, forcing many Pacific island nations and coastal communities in the United States to plan for permanent evacuation. Although low-lying areas will not “disappear” into the ocean anytime soon, nuisance flooding, erosion, and storm surges are making maintaining these communities economically untenable. “In 2009, then-British Prime Minister Gordon Brown predicted that the world had only 50 days to save the planet from global warming. But fifty days and years later, and the earth still spins.” Britta Voss Postdoctoral Research fellow, U.S. Geological Survey: This is extremely misleading. The article this claim refers to reports that Gordon Brown stated that the 2009 Copenhagen Climate negotiators had 50 days to adopt an adequate agreement to prevent catastrophic climate change. The time span of 50 days is inaccurately used by the author here to suggest that Brown thought the world—rather than the negotiations—would end in 50 days. “…scientist James Hansen unequivocally stated: ‘We have at most ten years—not ten years to decide upon action, but ten years to alter fundamentally the trajectory of global greenhouse emissions.'” Victor Venema Scientist, University of Bonn, Germany: The classic because-x-did-not-happen-yet-thus-x-will-not-happen fallacy. A fallacy that is especially ignorant in the case of a problem like climate change which responds slowly, like an oil tanker… “Time is up on Gore’s ‘point of no return’ and Hansen’s ‘critical tipping point.’ But the two fathers of the global-warming movement (Hansen and Gore got it going back in the summer of 1988) have nary admitted their exaggeration nor set a new timetable for effective action.” Mike MacCracken Chief Scientist for Climate Change Programs, Climate Institute: Bradley indicates no understanding of the time it will take to change over the global fossil-fuel energy system and the inertia of the climate system. Observations are already showing that the accelerating loss of ice from the Greenland and Antarctic ice sheets is giving indications of committing the world to a few meters (roughly 5-10 feet) of rise in global sea level over the next few centuries, which would seriously disrupt many coastal cities and swamp a number of island nations—and there is no indication that actions to reduce emissions can reverse this commitment—so, we are indeed moving past the point where emissions cutbacks can keep sea level and climatic conditions near to the conditions that have allowed civilization to flourish over the past several centuries 3. The weight of evidence indicates that climate change presents a serious risk to societies around the world. “Sensitivity estimates—defined as the temperature effect from the enhanced greenhouse effect—have been coming down in the peer-reviewed literature…” Kyle Armour Assistant Professor, University of Washington: This statement is somewhat misleading. Estimates of equilibrium climate sensitivity have been coming down in one branch of the literature that uses global energy budget observations (e.g. Otto et al 2013). However, recent work suggests that those energy budget estimates are biased low, moving estimates back up again once those biases are corrected for (see my recent commentary*). Meanwhile, estimates of sensitivity from other methods (e.g., paleoclimate, process-based observational constraints or climate model simulations) haven’t budged. Altogether, I don’t see any reason that the IPCC range isn’t still our best guess. Kyle C. Armour (2016) Projection and prediction: Climate sensitivity on the rise, Nature Climate Change “climate economists see a positive externality, not a negative one, from the human influence on climate. (In technical lingo, the so-called social cost of carbon would be negative.)” Gary Yohe Professor of Economics and Environmental Studies, Wesleyan University: This is cherry-picking at its worst. You can always find an economist who will make enough assumptions so that he or she can give you the answer you want. In this case (references the social cost of carbon), you can get a benefit ONLY if you assume a very high discount rate (like 5% so that future generations do not matter), and you ignore equity issues, and you assume that warmer climates in the crop-intensive areas will not include an increase in the intensity and/or frequency of intense weather (drought, floods, etc….), and you do not recognize that warmer temperatures mean more pests and more weeds. see the Summary: for Policymakers of the Report of Working Group II to the fourth assessment of the IPCC Richard Tol Professor of Economics, University of Sussex: The social cost of carbon would indeed be negative for a low climate sensitivity. This is because the net impacts of climate change only turn negative at more pronounced warming, and this would occur in a more distant future for a low climate sensitivity. At the same time, the positive impacts of carbon dioxide fertilization would be unaffected. Mike MacCracken Chief Scientist for Climate Change Programs, Climate Institute: The present calculations of the “social cost of carbon” tend to be bottom up and so include only those costs that one can reasonably quantify. As a result many types of impacts are simply left out of the calculation, like the cost of losing the culture of an island nation that is swamped, the impacts of ocean acidification and biodiversity loss, the actual social cost of climate change (e.g., of the New England climate becoming that of the Southeast, Sweden like Spain, etc.)… Britta Voss Postdoctoral Research fellow, U.S. Geological Survey: At a minimum, the author should be honest and say that “some climate economists” conclude that the net externalities of climate change may be positive, as the article he links to discusses only the economic views of its author and anecdotes from two climate scientists. Further, the article the author links to discusses only the net economic impacts on “the US and most of the developed countries”, while climate change will impact economies around the globe. This is not a meaningful argument anyway, as the exact value of the climate sensitivity does not inherently determine whether climate impacts will be economically net positive or negative. Frank Vöhringer Dr. rer. pol, Scientist, Ecole Polytechnique Fédérale de Lausanne (EPFL): There are positive and negative economic consequences of climate change. On a global level and for average temperature increases of more than 2 degrees Celsius, most climate economists find a negative influence of climate change on human welfare (and even more clearly on ecosystems), although negative net damages have been calculated in some instances. Net damages tend to be more pronounced in tropical countries, which usually have lower per capita incomes. For this reason, purely consumption-based global aggregations of climate impacts tend to show lower net damages than aggregations which consider differences in the marginal utility of income across countries. The evaluation of the net damages thus depends on whether the impacts on poor countries are properly considered. Indeed, the issue of international aggregation of benefits and damages is ethically problematic to an extent that calculating a social cost of carbon at a global level may conceal more than it reveals. 4. The article builds on unsupported assertions and accusations and logical fallacies. “Falsified and sure-to-be-falsified exaggerations from a parade of Ph.D. scientists” Britta Voss Postdoctoral Research fellow, U.S. Geological Survey: The author does not provide any evidence of “falsified” scientific reports of climate predictions or observations. “Peter Wadhams, professor of ocean physics at the University of Cambridge, predicted ‘global disaster’ from the demise of Arctic sea ice—in four years. He too, is eating crow.” Victor Venema Scientist, University of Bonn, Germany: These predictions of Peter Wadhams have been opposed by all climate scientists I know of. This picking of quotes that are convenient for Robert Bradley Jr.’s narrative while ignoring what most climate scientists say is one of his most used rhetorical tools. Kyle Armour Assistant Professor, University of Washington: Indeed. Wadham’s claims have been roundly refuted by the climate science community. They are certainly an example of exaggeration, but to suggest that they somehow represent the scientific mainstream is a great distortion. [See Climate Feedback review of the latest prediction by P. Wadhams] “Can the “uncertainty monster” in climate research, and particularly climate modeling, be acknowledged?” Kyle Armour Assistant Professor, University of Washington: A quick look through the IPCC assessment reports reveals long discussions about uncertainty in our understanding and climate prediction. Moreover, uncertainty in global warming projection exists mainly at the high end—toward more warming—for simple physical reasons. Gary Yohe Professor of Economics and Environmental Studies, Wesleyan University: The scientific community has been scrupulously careful to report uncertainties in terms of “likely” or “confidence”. The planet has warmed; that is unequivocal. Humans have contributed; that is more than 95% assured. See: IPCC 5th Assessment Report Victor Venema Scientist, University of Bonn, Germany: The “uncertainty monster” is a reason to act faster. Uncertainties about how strongly the climate will respond makes the risks of climate change larger. “…obsessing about climate change is avoiding a frank discussion about the here-and-now problems of budget deficits, the federal debt, school choice, entitlement reform, and so on.” Jeremy Fyke Postdoctoral researcher, Los Alamos National Laboratory: Of course, this is a classic false dilemma used by climate change contrarians, which claims that you can’t deal with climate change AND other issues simultaneously. This is patently wrong. “Not only do polls suggest the public is unmoved at home and in abroad…” Britta Voss Postdoctoral Research fellow, U.S. Geological Survey: This claim is incorrect. The source given to support “the public is unmoved at home” is an article titled “Poll: 91% Of Americans Aren’t Worried About Global Warming.” However, this article reports that “only 9.2 percent of Americans rank global warming as their biggest concern.” Not ranking global warming as your biggest concern is not the same thing as not being concerned at all. According to a 2016 Gallup survey, 64% of Americans are “worried a ‘great deal’ or ‘fair amount'” about global warming:

https://science.feedback.org/review/greenlands-huge-annual-ice-loss-is-even-worse-than-thought-damian-carrington-the-guardian/

1.6

The Guardian, by Damian Carrington, on 2016-09-23.

"Greenland's huge annual ice loss is even worse than thought"

Damian Carrington’s article in the Guardian is an accurate summary of a new study advancing estimates of ice lost from Greenland. One of the factors that must be accounted for when monitoring the size of the great ice sheets of Greenland and Antarctica is the vertical motion of the land beneath the ice due to geological forces. The Earth’s crust is depressed under the weight of a growing ice sheet, and will rebound upwards as the ice sheet shrinks. Carrington’s article describes a new study finding greater “crustal rebound” in Greenland, which means some methods of estimating the loss of Greenland ice will have underestimated that loss. The reviewers pointed out that, while this work is important, it doesn’t constitute as much of a breakthrough as is suggested in the article, but mostly confirms that the rate of Greenland ice melt is now 3 times what it was before the industrial revolution.See all the scientists’ annotations in contextGUEST COMMENTS: While I would have preferred a slight moderation of the headline (replace ‘worse’ with e.g. ‘greater’ or ‘larger’) I find the headline accurate and supported by the article. The article explains the novelty and impact of the research accurately for the general readership and in particular the context provided from the scientists works really well in this regard.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Martin Truffer Professor, University of Alaska Fairbanks: The article might not explain the relevance of this work all that well, but there is really nothing controversial being presented here. The Science article presents some important new measurements, but there is no fundamental difference to what we understand about how the icesheet works. Twila Moon Research Scientist, University of Colorado, Boulder: A well-written article that accurately discusses the scientific study and the current state of Greenland research. Allen Pope Research Associate, National Snow and Ice Data Center, University of Colorado Boulder: The article does a good job of accurately portraying and providing insight to the science. A clearer focus on the different timescales involved might have improved it, but it is very good. Lauren Simkins Assistant Professor, University of Virginia: Carrington’s article is a succinct and accurate assessment of past and present ice mass loss from the Greenland Ice Sheet that is supplemented by insightful comments from scientific experts. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from Damian Carrington; comments and replies are from the reviewers. 1. A new estimate of the vertical motion of Greenland’s land surface implies that some monitoring of the Greenland ice sheet has slightly underestimated recent ice loss, which has accelerated due to human-caused warming. “the rapid ice loss recorded by satellite measurements over the last 20 years is not likely to be a blip, but part of a long-term trend being exacerbated by climate change. Global warming is driving major melting on the surface of Greenland’s glaciers and is speeding up their travel into the sea.” While this paragraph is not imprecise, there is a slight wiggle room for the wrong interpretation that the acceleration of ice loss seen in the past decades is just a “blip” on top of a much larger rate of mass loss since the Last Glacial Maximum (LGM). This new work finds the contribution to sea level rise from the Greenland Ice Sheet since the LGM to be 4.6 ± 0.7 m – an average ice loss rate of roughly 75-80 Gt/yr, which is almost identical to the rate of ice loss in the 20th century (75 Gt/yr) suggested by Kjeldsen et al. (2015). The rate of ice loss has accelerated in the past decades so that we today see rates that are more than the triple of those earlier rates. However, I do not think this is a major issue, as the paragraph is sandwiched in between precise explanations and context provided by scientists. Allen Pope Research Associate, National Snow and Ice Data Center, University of Colorado Boulder: Yes, there are two processes going on here: 1) changes still happening in the solid Earth from the last ice age and 2) current changes to the Greenland ice sheet. The former is impacting our ability to measure the latter. “Previous satellite estimates of modern ice losses tried to take this into account, but precise new GPS data showed much of Greenland is rising far more rapidly than thought, up to 12mm a year. This means 19 cubic kilometres more ice is falling into the sea each year, an increase of about 8% on earlier figures.” When scientists use modern data from e.g. satellite gravity measurements to estimate present-day ice loss, we need to correct for land uplift. Because the satellite sees that mass is changing below, but it cannot tell what is due to land motions and what is due to ice loss. The huge Sumatra earthquake caused huge land displacements and changed the gravity field. But for Greenland, changes in gravity are both due to land displacements and ice mass “displacements” or “ice loss”. This new paper solves the problem by using direct GPS measurements of land displacements. Ian Joughin Affiliate Professor, University of Washington: It’s a nice study, but the 20GT/yr represents less than 10% of the observed signal and is well within the uncertainty of those measurements (263+/-30 Gt/year – 2005-2010 loss from Shepherd et al, 2012). Moreover, it’s not clear how well sparsely sampled points constrain their estimates, so there is some uncertainty on the 20Gt/yr (it could be more or less). So while we are always striving to improve measurements of ice sheet mass loss, and this is a step in the right direction, it doesn’t produce any fundamental change in the current estimates of rates of loss from the Greenland ice sheet. Allen Pope Research Associate, National Snow and Ice Data Center, University of Colorado Boulder: It might be worth noting that only some satellite estimates need to take this into account. Especially gravity-based mass change recoveries will be impacted while elevation-change or input/output methods will not. Projects like IMBIE intercompare different methods to build consensus among them. 2. The loss of ice from the Greenland Ice Sheet is a major source of global sea level rise , after thermal expansion of ocean water and melting mountain glaciers outside the polar regions. “The melting Greenland ice sheet is already a major contributor to rising sea level and if it was eventually lost entirely, the oceans would rise by six metres around the world, flooding many of the world’s largest cities.” Lauren Simkins Assistant Professor, University of Virginia: To expand on this statement, observations of ice mass loss indicate that the Greenland Ice Sheet contributes 0.33 [0.25-0.41] mm/yr to global sea level rise. Contributions from thermal expansion and glaciers outside of Antarctica and Greenland are currently the major contributors to global sea level rise followed by contributions from the Greenland Ice Sheet. While it is important to recognize the potential sea level equivalents held up in current ice sheets, complete loss of the Greenland Ice Sheet by 2100 is not reasonable and would likely take thousands of years. For a paleo-perspective, Greenland ice cores and ice sheet models demonstrate that parts (now which parts are up for debate) of the Greenland Ice Sheet did collapse during the last interglacial period (~125,000 years ago) when global mean atmospheric temperature was ~1 degrees C warmer than pre-industrial temperature; however, sectors of the ice sheet remained intact. W. Tad Pfeffer,Professor, University of Colorado: This number [six meters] is quoted in virtually every article published about Greenland (in media and science literature!). It’s really an irrelevant number, and without any context can be very misleading, as it is here. The total loss of the Greenland ice sheet may not happen under any reasonable future scenario, and in any case would take many thousands of years to occur. A more meaningful number would be the current estimate of what the net loss might be by 2100; this could then be given as a percentage of the total ice volume on Greenland, but for the purposes of an article like this, where the reader is thinking about human consequences, quoting the total ice volume will only confuse the issue. Note: While the term “ice cap” is commonly used to refer to several different types of polar features, it technically refers to much smaller areas than Greenland, which should be called an “ice sheet”. “Ice cap is disappearing far more rapidly than previously estimated, and is part of a long-term trend, new research shows” Twila Moon Research Scientist, University of Colorado, Boulder: Again, “ice sheet” is more accurate than “ice cap”. In general, the term “ice cap” is not used in scientific literature. As a result, I think its use is confusing in the media, too, as people have a hard time understanding if it refers to ice sheets (thick ice on land) or sea ice (which are very different!).

https://science.feedback.org/review/flooding-of-coast-caused-by-global-warming-has-already-begun-justin-gillis-the-new-york-times/

1.7

The New York Times, by Justin Gillis, on 2016-09-03.

"Flooding Coast, Caused by Global Warming, Has Already Begun"

Writing for the New York Times, Justin Gillis links the issue of global sea level rise due to climate change to examples of “sunny-day flooding” at high tide along the US East Coast. The 12 scientists who reviewed the article found that it accurately described sea level data and research. Global sea level has risen about 20 centimeters (8 inches) over the past century, contributing to an observed increase in coastal flooding. However, multiple factors affect flooding in coastal communities and many locations along the US East Coast have experienced an even larger sea level change due to additional local factors. The article also discusses research into future sea level rise based on records of past climate changes. While climate scientists generally think that sea level rise will not be greater than 1-2 meters (3.3-6.6 feet) this century, previous warm periods indicate that greater long-term sea level rise should follow in coming centuries—but precisely how much, and how quickly, is not well known. Around 125,000 years ago, for example, the Earth was probably about 1-2°C warmer than it is today, but global sea level may have been 6 meters (20 feet) higher.See all the scientists’ annotations in contextGUEST COMMENTS: Robert Nicholls Professor of Coastal Engineering, University of Southampton: I find this a compelling piece of journalism translating our emerging scientific understanding into an accessible and credible form. It brings home to readers that sea-level rise impacts are being experienced today on the US Atlantic coast. The theory of sea-level rise and flood problems is pretty well understood — this makes the point that this theory is also happening now and can only be expected to get worse — sea levels have been rising on the US east coast for the last 150 years or more and even if current trends simply continue, impacts will continue to grow. As the article states, we actually expect a significant acceleration of sea-level rise in the coming decades meaning the impacts will grow more rapidly. The discussion of the public policy aspects of the issue is also important and shows that we need to start adapting to these changes now — they are only going to get worse.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Andrea Dutton Visiting Associate Professor, University of Wisconsin: This article is well-researched and demonstrates an understanding of the nuances related to the rates of sea-level rise, and how it varies in time and space. This article does a good job at conveying the state of the science and including supporting anecdotal information regarding the inundation of the coastal U.S. due to sea-level rise. Alexis Berg Research Associate, Harvard University: The parts of this article that report on climate science are accurate. In my view, the only thing is that issue of short-term (by 2100) vs long-term (next few centuries) sea level rise projections could perhaps have been explained a bit more clearly: even though total sea level rise by the end of the century is quite uncertain, a sustained 2°C warming almost certainly guarantees a 6 meters sea level rise over the next several centuries. Aimée Slangen Researcher, Royal Netherlands Institute for Sea Research (NIOZ): As far as I can judge, the article is scientifically sound and refers to up-to-date literature, interviewing knowledgeable scientists in the field. I would have liked to see a bit more nuance around the ‘melt’ of land ice though. Lauren Simkins Assistant Professor, University of Virginia: This article supports local perspectives on sea-level rise in the United States with accurate, yet qualitative, scientific observations. Mike MacCracken Chief Scientist for Climate Change Programs, Climate Institute: While there is no real discussion in this article about other factors affecting the coastline (e.g., land subsidence and emergence, local projects that affect movement of sand, the digging of trenches through coastal wetlands, etc.), the contribution resulting from global climate change affecting sea level rise is increasingly dominating the contributions of other factors in most locations. That the present rise of a bit less than a foot since the 19th century is already having so much influence should help to justify the significance and concern in the scientific and defense communities and increasingly in some communities and states regarding the projected additional rise in sea level of two feet and possibly double that over the 21st century. The real uncertainty is becoming not how much the rise will be in the year 2100, but that the world is becoming committed to an ongoing rate of rise of a few to several feet per century, and that what is uncertain is exactly when that much rise will occur rather than if it will occur. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from Justin Gillis; comments and replies are from the reviewers. 1. Average global sea level has risen about 20 centimeters (8 inches) over the last century, and this has contributed to an increase in flooding events at high tide, notably along the US East Coast. “Federal scientists have documented a sharp jump in this nuisance flooding — often called ‘sunny-day flooding’ — along both the East Coast and the Gulf Coast in recent years. The sea is now so near the brim in many places that they believe the problem is likely to worsen quickly.” William Sweet Oceanographer, NOAA Center for Operational Oceanographic Products and Services: This refers to the historical analysis of “nuisance” tidal flooding frequencies (days per year) which we assessed in Sweet et al. (2014). In this report we looked at all tide gauges with hourly data since 1980 and with a threshold for “minor” impacts. When minor flooding (nuisance) is expected, the Weather Forecasting Offices (WFO) typically issues a “coastal flood advisory”; they issue a coastal flood warning when levels are expected to reach moderate or major levels. The minor thresholds I started calling “nuisance levels” and the phrase caught on. Generally nuisance levels vary from 1-2 feet around the U.S. The National Weather Service has a website (AHPS) that includes some of the tide gauge thresholds along with river gauges. Sweet et al (2014) Sea Level Rise and Nuisance Flood Frequency Changes around the United States, NOAA Technical Report Joshua Willis Project Scientist, NASA Jet Propulsion Laboratory: This is accurate. Global sea levels have risen by about 20 cm due to human induced global warming in the last 100 years. Both US coasts have experienced this. It is true that subsidence on the east coast has exacerbated this and the last 20 years of natural variations on the west coast may have given folks a false sense of security because it has opposed or hidden the global rise experienced almost everywhere else. “Along the East Coast, scientists with the National Oceanic and Atmospheric Administration say that many communities have already, or will soon, pass a threshold where sunny-day flooding starts to happen much more often.“ William Sweet Oceanographer, NOAA Center for Operational Oceanographic Products and Services: This relates to the Sweet and Park (2014) paper that uses a 30 days/year threshold as a definition of a tipping point. Though the 30 days/year threshold is somewhat arbitrary, it is sufficiently high that once a region experiences this many floodings, the conversation of what to do to address sea level rise tidal flooding has likely forefront. The “soon” part refers to the fact that number of flooding days per year has (East and Gulf Coast locations) and will continue to accelerate with steady (linear) rises in sea level. Sweet and Park (2014) Acceleration and tipping points of coastal inundation from sea level rise “These tidal floods are often just a foot or two deep, but they can stop traffic, swamp basements, damage cars, kill lawns and forests, and poison wells with salt.” Andrea Dutton Visiting Associate Professor, University of Wisconsin: The depth of flooding is accurate as stated, as shown in Fig. 2 of Sweet and Park (2014) 2. Besides climate change, sea level at any particular location depends on several factors, including local subsidence (lowering of land elevation that can be caused by human activities like groundwater depletion), patterns of ocean circulation… “Federal scientists have documented a sharp jump in this nuisance flooding — often called ‘sunny-day flooding’ — along both the East Coast and the Gulf Coast in recent years.” Benjamin Horton Professor, Earth Observatory of Singapore: This is a tricky one. Nuisance flooding on the Atlantic and Gulf coasts is the result of relative sea-level rise. Relative sea-level rise has a variety of components that give the rise a spatial signature. For example along the mid US Atlantic coast one-third of the rise is due to glacial isostatic adjustment with the remainder dominated by climatically driven sea-level rise. But in the Mississippi Delta the dominant driving force is subsidence. However, in the coming century these components will decrease in importance relative to climatically driven sea-level rise. “Because the land is sinking as the ocean rises, Norfolk and the metropolitan region surrounding it, known as Hampton Roads, are among the worst-hit parts of the United States.” Andrea Dutton Visiting Associate Professor, University of Wisconsin: This statement about the land sinking in the region of Norfolk, leading to higher rates of sea level rise is correct, and is supported by plenty of research, including: Kopp et al. (2014 Probabilistic 21st and 22nd century sea-level projections at a global network of tide-gauge sites, Earth’s Future) “On the Pacific Coast, a climate pattern that had pushed billions of gallons of water toward Asia is now ending, so that in coming decades the sea is likely to rise quickly off states like Oregon and California.” Matthieu Lengaigne Senior Researcher, Institut de Recherche pour le Développement: This statement is likely to be accurate. Several papers already demonstrated the influence of decadal ENSO (El Niño) variations (or the Pacific Decadal Oscillation; PDO) onto the large-scale decadal sea-level variations in the Pacific Ocean (e.g. Zhang and Church 2012). Bromirski et al. (2011) specifically addressed the influence of decadal PDO/ENSO onto the west coast of America and demonstrated an influence of the PDO there, with a suppression of sea-level rise from the 80’s until 2005. As the decadal ENSO/PDO phase is reversing, there is over the past five years an accelerated sea-level rise over the west coast of America (Hamlington et al. 2016) that should continue in the next decade. Zhang and Church (2012) Sea level trends, interannual and decadal variability in the Pacific Ocean. Geophys Res Lett Bromirski et al. (2011) Multidecadal regional sea level shifts in the Pacific over 1958-2008. J Geophys Res. Hamlington et al. (2016) An ongoing shift in Pacific Ocean sea level. Journal of Geophysical Research: Oceans. 3. While global sea level has been stable throughout human civilization history, continuing greenhouse gas emissions growth could result in a sea level rise of 0.5 meters (20 inches) to as much as 1 or 2 meters (3.3-6.6 feet) by the year 2100. But even if rising temperatures are stabilized this century, the world’s ice sheets could continue to shrink long into the future, raising sea levels several meters over coming centuries. “In 2013, scientists reached a consensus that three feet was the highest plausible rise by the year 2100. But now some of them are starting to say that six or seven feet may be possible.” Benjamin Horton Professor, Earth Observatory of Singapore: Yes, I couldn’t agree more. I actually wrote a paper regarding a survey of sea-level scientists. The concluding statement was that most experts estimate a larger sea-level rise by AD 2100 than the IPCC’s Fifth Assessment Report AR5 projects: Horton, Rahmstorf, Engelhart, and Kemp (2014) Expert assessment of sea-level rise by AD 2100 and AD 2300. Quaternary Science Reviews Richard Alley Professor, PennState University: In the 2013 IPCC report, there is a reference period (1986-2005), there is an assumption of a reference pathway of future emissions, and there is a confidence assigned to the estimate. That being said, I think the statement is pretty good. The second sentence is I believe accurate; the work by DeConto and Pollard, building on Pollard et al. (note that I’m involved in this study), for example, points to the possibility of rapid warming triggering rapid sea-level rise. Ken Caldeira Senior Scientist, Carnegie Institution for Science: This is a correct statement, but a key word is ‘some of them’. There have been some people, notably Jim Hansen, who, as I understand it, have been proposing high rates of sea-level rise without providing a mechanism for these sea-level rise rates that seemed plausible to most glaciologists. It is my understanding that the mechanisms proposed by DeConto and Pollard (i.e., mechanical instability of ice cliffs) does appear to be plausible and has some support in observations of ice shelf break-up that has already occurred in Antarctica. In other words, if this sentence were written a year ago, “some of them” would have referred to a few scientists who hold what might be considered ‘outlier’ views. Following the work of DeConto, Pollard, and others, my sense is that the risk of very high rates of sea-level rise seems substantially higher, even to what might be considered ‘mainstream’ scientists. “But the air is already so full of greenhouse gases that most land ice on the planet has started to melt.” Richard Alley Professor, PennState University: Not sure how I would parse “most of the land ice has started to melt”. It is true that there is net mass loss from most mountain glaciers, the Greenland Ice Sheet, and the West Antarctic ice sheet, which numerically makes most of the land ice. But, much of the ice remains too cold to melt, the big central region of East Antarctica is not melting, and much of the sea-level rise from the Antarctic is from faster flow into the ocean (after which the ice does melt…) rather than from melting in place. Aimée Slangen Researcher, Royal Netherlands Institute for Sea Research (NIOZ): I think this is not a very accurate statement and should be nuanced. Rather than ‘melt’, one should talk about ‘mass loss’ (or ‘mass gain’), as melt is not the only process adding to sea-level change. Especially on Antarctica, ice discharge [ice sliding into the ocean] plays a much more important role than melt, as over large parts of the Antarctic Ice Sheet (i.e. inland East Antarctica) the temperatures are so low that surface melt, even in summer, is not an issue at present (see eg these maps of Antarctica surface melt area). If we step away from the ‘melt’ however, […] most glaciers on Earth are suffering from mass loss (IPCC AR5 Chapter 4: “Since AR4 (in 2007), almost all glaciers worldwide have continued to shrink as revealed by the time series of measured changes in glacier length, area, volume and mass”). […] “In the worst-case scenario, this research suggests, the rate of sea-level rise could reach a foot per decade by the 22nd century, about 10 times faster than today.” Ken Caldeira Senior Scientist, Carnegie Institution for Science: We published the results of a study in Science Advances last year (Winkelmann et al., 2015; Combustion of available fossil fuel resources sufficient to eliminate the Antarctic Ice Sheet) concluding that in a worst case scenario, sea level could be rising at an average rate of a foot per decade, averaged over the next 1000 years. Our model, however, did not include the mechanical instability of ice sheet cliffs considered by DeConto and Pollard (2016; Contribution of Antarctica to past and future sea-level rise), which could potentially result in sea-level rises of this magnitude. A key word here is ‘could’. More work needs to be done to assess the likelihood of this occurrence, but sea-level rise rates of a foot per decade by year 2100 appear to be a real risk posed by our greenhouse gas emissions. “During ice ages, caused by wobbles in the Earth’s orbit, sea levels dropped more than 400 feet as ice piled up on land. But during periods slightly warmer than today, the sea may have risen 70 or more feet above the current level.the last sea-level high point, … occurred between the last two ice ages, about 125,000 years ago. … scientists determined that the sea level rose by something like 20 to 30 feet in that era, compared with today. “ Alexis Berg Research Associate, Harvard University: This part would perhaps be a little bit clearer for readers if it included estimates of global temperature change during these different times, to associate with these numbers on sea level change. The last ice age, at its coldest, is estimated to have been on the order of 5 degrees Celsius cooler, in terms of global average, than today. As the article mentions, sea levels then were ~400 feet lower. The last interglacial preceding it, which Dr. Dutton’s research focuses on, was perhaps 1-2C warmer than today (today meaning the pre-industrial climate, before the warming of the recent decades). As the article indicates, sea-levels were perhaps ~6 meters higher at the time. Citing these numbers would help put into perspective, for readers, the projected man-made warming of a few degrees Celsius globally, and explain why the long-term expectations of many scientists … are that sea levels will ultimately rise, over centuries, by “at least 15 or 20 feet” if the globe warms by several degrees in a sustained manner. The questions remains of course, how fast that will occur. Uncertainties on possible rates of sea level rise explain why sea level numbers by 2100 are so uncertain; but what’s virtually certain is that sea level will continue rising beyond that. “Through decades of research, it has become clear that human civilization, roughly 6,000 years old, developed during an unusually stable period for global sea levels.” Andrea Dutton Visiting Associate Professor, University of Wisconsin: The last 6,000 years have been unusually stable for the period of time that we are able to constrain rates of sea-level change particularly well (at sub-millennial timescales): see, for example, Lambeck et al (2014) Sea level and global ice volumes from the Last Glacial Maximum to the Holocene.

https://science.feedback.org/review/sea-level-rise-much-1-2-meters-3-3-6-6-feet-year-2100/

Correct

The New York Times, Justin Gillis, 2016-09-03

Sea level rise could reach six or seven feet by the year 2100.

Continuing greenhouse gas emissions growth could result in a sea level rise of 0.5 meters (20 inches) to as much as 1 or 2 meters (3.3-6.6 feet) by the year 2100.

In 2013, scientists reached a consensus that three feet was the highest plausible rise by the year 2100. But now some of them are starting to say that six or seven feet may be possible.

Benjamin Horton Professor, Earth Observatory of Singapore: Yes, I couldn’t agree more. I actually wrote a paper regarding a survey of sea-level scientists. The concluding statement was that most experts estimate a larger sea-level rise by AD 2100 than the IPCC’s Fifth Assessment Report AR5 projects: Horton, Rahmstorf, Engelhart, and Kemp (2014) Expert assessment of sea-level rise by AD 2100 and AD 2300. Quaternary Science Reviews Richard Alley Professor, PennState University: In the 2013 IPCC report, there is a reference period (1986-2005), there is an assumption of a reference pathway of future emissions, and there is a confidence assigned to the estimate. That being said, I think the statement is pretty good. The second sentence is I believe accurate; the work by DeConto and Pollard, building on Pollard et al. (note that I’m involved in this study), for example, points to the possibility of rapid warming triggering rapid sea-level rise. DeConto and Pollard (2016)Contribution of Antarctica to past and future sea-level rise, Nature Pollard et al (2015) Potential Antarctic Ice Sheet retreat driven by hydrofracturing and ice cliff failure, Earth and Planetary Science Letters Ken Caldeira Senior Scientist, Carnegie Institution for Science: This is a correct statement, but a key word is ‘some of them’. There have been some people, notably Jim Hansen, who, as I understand it, have been proposing high rates of sea-level rise without providing a mechanism for these sea-level rise rates that seemed plausible to most glaciologists. It is my understanding that the mechanisms proposed by DeConto and Pollard (i.e., mechanical instability of ice cliffs) does appear to be plausible and has some support in observations of ice shelf break-up that has already occurred in Antarctica. In other words, if this sentence were written a year ago, “some of them” would have referred to a few scientists who hold what might be considered ‘outlier’ views. Following the work of DeConto, Pollard, and others, my sense is that the risk of very high rates of sea-level rise seems substantially higher, even to what might be considered ‘mainstream’ scientists.

https://science.feedback.org/review/arctic-will-be-ice-free-in-summer-next-year-robin-mckie-peter-wadhams-the-guardian/

-0.6

The Observer, The Guardian, by Robin McKie, Peter Wadhams, on 2016-08-21.

"Next year or the year after, the Arctic will be free ice"

The Guardian published an interview with Peter Wadhams, who discusses the consequences of human-induced global warming on Arctic climate and opines that “Next year or the year after, the Arctic will be free of ice”. This claim appears not to be supported by proper scientific argumentation based on evidence and a physical understanding of how that forecast would realize, either in the article or in previously published scientific papers. The scientists who have reviewed the article indicate that while some statements are science-based, several claims are inaccurate or are opinions unsupported by current science. Most of the scientists tagged the article as ‘alarmist’ (meaning that “it overstates or exaggerates the risks of climate change”) and most indicated that the title of the article is not properly supported by its content. Widely publicizing this kind of guess, which has a low probability of turning out to be true, risks undermining public trust in science. Note: scientists’ ratings are intended to assess the credibility of the information contained in an article, regardless of whether a journalist or an “expert” is the author.See all the scientists’ annotations in contextGUEST COMMENTS: Kyle Armour Assistant Professor, University of Washington: The article contains numerous statements that are not supported by the scientific literature, but instead appear to be the personal opinion of Professor Wadhams. It is difficult to provide any meaningful rating for such an interview piece — Wadhams has the right to share his opinions when asked (however unsupported they may be) and at times even makes it clear that his statements are far outside the scientific mainstream. But I give the article low marks overall since it makes no attempt to distinguish which statements are rooted in science and which are simply speculation. Ed Hawkins Principal Research Fellow, National Centre for Atmospheric Science: Peter Wadhams’ views are well known to lie far outside the scientific mainstream. He makes several statements that are inaccurate and some are alarmist. There is no balance in the article from a more mainstream scientist.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Alexis Berg Research Associate, Harvard University: The interview/article should make it clearer that the claim by Prof Wadhams that the Arctic sea ice will be gone this year or next is at odds with mainstream climate science on that topic, and that he has repeatedly made such predictions that haven’t been borne out by subsequent observations. One could argue that climate model projections regarding Arctic sea ice are dire enough that there is no need to repeatedly provide unsubstantiated “guesstimates” of imminent collapse, and that doing so might even detract the public from the slower, but all too real, steady decline in sea ice, or even worse, that it eventually decreases the public’s trust in climate scientists. Allen Pope Research Associate, National Snow and Ice Data Center, University of Colorado Boulder: I gave the “low” rating because the article’s discussion of expected Arctic sea ice retreat is misleading and inaccurate. The statements are not solidly based on the most up to date science. Lauren Simkins Assistant Professor, University of Virginia: While the basic topics mentioned in the article are important to address, some of the statements are misleading and alarmist and the article is more of an opinion piece than a science-supported point. Rasmus Benestad Senior scientist, The Norwegian Meteorological institute: The question concerning sea ice is tricky due to the many and complex factors involved, and the lack of good ice models that embody all scales involved. Patrick Grenier Specialist in climate scenarios, Ouranos: This interview article covers and links several issues (sea ice projections, seabed methane bubbling, carbon capture, etc.), and I agree with some of the messages. The central claim, as conveyed by the title, is that disappearance of the summer Arctic sea ice cover will occur either in 2017 or in 2018. This is not what most sea ice experts consider. Before propagating a marginal view, one should ensure having a very strong argumentation; in this interview no argumentation is put forward to support Peter Wadhams’ central claim. The journalist has chosen to interview a researcher known for having made wrong predictions in the past, and he has chosen not to balance Wadham’s view against that of other sea ice experts. Wadhams’ alarmism is potentially harmful, because when such spectacular predictions are not realized some people may perceive the whole scientific community or science itself as untrustworthy. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from Peter Wadhams; comments and replies are from the reviewers. 1. Sea ice in the Arctic is currently melting at an unprecedented rate and, based on current scientific understanding, one can expect the Arctic to become ice free in summer in about 30-40 years. It is extremely unlikely that the Arctic will become ice free within the next 2 years as claimed in the Guardian article. “Ice-free means the central basin of the Arctic will be ice-free and I think that that is going to happen in summer 2017 or 2018.” Alexis Berg Research Associate, Harvard University: Readers should be reminded that under a business-as-usual greenhouse gas emissions scenario, climate models project an “ice-free” (less than 1 million km2 of ice) Arctic in September by ~2050. Peter Wadhams claims almost every year that it will happen sooner than that, in a matter of a few years – implying some total collapse of Arctic sea ice. This hasn’t happened so far, even if Arctic sea ice is decreasing a bit more rapidly than most models predict. I am borrowing this telling graph from Ed Hawkins (more details in this post):Kyle Armour Assistant Professor, University of Washington: There is no reason to believe that the sea ice cover will disappear this quickly. Our best estimate for this comes from climate models projections, which show that the Arctic could become ice free (less than a million square km) by mid-century — at the earliest — under business-as-usual emissions. Observations show that sea ice is declining somewhat faster than models predict, but even accounting for this suggests that an ice-free Arctic is decades away. Patrick Grenier Specialist in climate scenarios, Ouranos: It is not clear whether a permanent or a one-year phenomenon is meant here (probably the former), but in any case the scientific support for the claim is weak. In the former case (permanent disappearance), this would not correspond to what most sea ice experts do consider. Indeed, section 11.3.4.1 of the last (2013) IPCC assessment report suggests a very low probability for permanent disappearance within the current decade. In fact, from the scientific literature it seems the phenomenon is more likely to take place during the period 2040-2060. Of course, a very low probability does not necessarily mean a zero probability, and IPCC’s report could possibly underestimate the odds for disappearance within the next few years. But before propagating a marginal view (relative to IPCC conclusions), one should ensure having a very strong argumentation; in this interview no argumentation is put forward to support Peter Wadhams’ central claim. In the other possible case (isolated single-year disappearance), it has to be said sea ice has strong year-to-year variability superimposed on its long-term declining trend, and no one has the tools to precisely predict the outcome one year in advance. Seasonal-to-decadal prediction groups equipped with physically-based models have some potential prediction skill for lead times up to 12-24 months, but they currently cannot guarantee to be right for any specific forecast (e.g.: Seasonal Forecasts of the Pan-Arctic Sea Ice Extent Using a GCM-Based Seasonal Prediction System and Pan-Arctic and Regional Sea Ice Predictability: Initialization Month Dependence). So, if it turns out in 2017 or 2018 that Wadhams was right, it will have been luck more than justified certainty. “Next year or the year after that, I think it will be free of ice in summer and by that I mean the central Arctic will be ice-free. You will be able to cross over the north pole by ship. There will still be about a million square kilometres of ice in the Arctic in summer but it will be packed into various nooks and crannies” Ed Hawkins Principal Research Fellow, National Centre for Atmospheric Science: Professor Wadhams has been making this type of prediction in the media for several years, but they have not been borne out by the subsequent observations. For example: Telegraph, 2011 – “ice free by 2015”; Guardian, 2012 – “ice free by 2015 or 2016”; Financial Times, 2013 – “ice free no later than 2015”. Allen Pope Research Associate, National Snow and Ice Data Center, University of Colorado Boulder: I would also add that predictions of an ice-free Arctic (also defined as ~1 million square kilometers of remaining ice) are shown to be subject to quite a bit of uncertainty stemming from natural variability – on the order of about two decades. “Most people expect this year will see a record low in the Arctic’s summer sea-ice cover.” Ed Hawkins Principal Research Fellow, National Centre for Atmospheric Science: This is incorrect. The SIPN team (Sea Ice Prediction Network) have collected forecasts from 40 international groups and none are predicting a record low in 2016. 2. Arctic sea ice melting will make global warming more severe due to several self-reinforcing cycles (known as “positive feedbacks”). “People tend to think of an ice-free Arctic in summer in terms of it merely being a symbol of global change.” Lauren Simkins Assistant Professor, University of Virginia: This is a good point. Changes in one part of the Earth system due to warming are not in isolation and result in feedbacks in other parts of the Earth system. 2.1. When sea ice melts, less solar heat is reflected to space, leading to further warming of the ocean; this is known as the ‘albedo feedback’. “One key effect will be albedo feedback” Rasmus Benestad Senior scientist, The Norwegian Meteorological institute: Albedo is one effect, but it is moderated by cloud cover and only is effective during summer (winter gives dark “polar nights”). Other – perhaps equally important – factors involve the effect open sea has on exchange of moisture, the way temperature varies with height, cloud cover … “These effects could add 50% to the impact of global warming that is produced by rising carbon emissions.” Kyle Armour Assistant Professor, University of Washington: The sea-ice albedo feedback is thought to contribute about 10% to global warming (it’s the smallest of the various climate feedbacks); that’s including the impact of Antarctic sea-ice loss as well. So this estimate of 50% for Arctic sea-ice loss alone seems far too high. Alexis Berg Research Associate, Harvard University: These effects are admittedly included in climate models projections (even though sea ice disappears later in these models than Wadhams suggests here). What Wadhams is describing here is useful to understand these projections, but it doesn’t mean that these effects will come on top of current projections. 2.2. When frozen lands warms (around or at the bottom of the Arctic ocean), it releases methane, a powerful greenhouse gas. Evidence suggests that this “methane feedback” is not yet influencing our climate significantly. “Russian scientists who have investigated waters off their coast have detected more and more plumes of methane bubbling up from the seabed.” Ed Hawkins Principal Research Fellow, National Centre for Atmospheric Science: However, there is evidence from a dedicated field campaign that the methane in ocean plumes does not affect the atmosphere: Extensive release of methane from Arctic seabed west of Svalbard during summer 2014 does not influence the atmosphere “Underneath the permafrost there are sediments full of methane hydrates. When the permafrost goes, you release the pressure on top of these hydrates and the methane comes out of solution” Jeremy Fyke Postdoctoral researcher, Los Alamos National Laboratory: It’s unclear what is meant by ‘permafrost goes’. Nothing particularly ‘goes’ anywhere, it just melts (and has been naturally melting due to post-Last Glacial Maximum sea level rise and the resulting thermal flux due to shelf inundation). Consequentially, I would not expect the pressure seen by the underlying hydrates to decrease if the overlying permafrost degrades. In fact in the real world it will probably increase due to anthropogenic sea level rise. So it will necessarily be an anthropogenic temperature pulse, not a pressure pulse that will destabilize methane hydrates under relic permafrost. Finally, methane molecules in hydrates is not ‘in solution’ but rather in the hydrate crystalline lattice. 3. While sea ice melt does not directly cause the sea level to rise, it helps warm and melt on-land-glaciers (e.g. Greenland) that do cause sea level rise. “The most recent prediction of the Intergovernmental Panel on Climate Change (IPCC) is that seas will rise by 60 to 90 centimetres this century. I think a rise of one to two metres is far more likely.” Lauren Simkins Assistant Professor, University of Virginia: This range is not entirely accurate. Using different climate scenarios, global mean sea level is predicted to rise by 0.26 to 0.98 m by the end of the century. This does not include potential collapse of marine-based sectors of the Antarctic Ice Sheet, which could raise these estimates. Recent work suggests that Antarctica’s contribution to sea level could contribute more than 1 m to sea level rise on top of the IPCC AR5 estimates. Remark: Some of the article’s language is imprecise “the first scientists to show that the thick icecap that once covered the Arctic ocean was beginning to thin and shrink.” Lauren Simkins Assistant Professor, University of Virginia: Arctic sea ice is typically less than 4 m thick. The use of ‘ice cap’ traditionally implies a body of ice on land that covers less area than an ice sheet; however, the article discusses sea ice, not an ice cap, which is floating ice that forms due to freezing of surface water. Jeremy Fyke Postdoctoral researcher, Los Alamos National Laboratory: This is a misleading term. Ice caps are technically large land-based glaciers, whereas I think ‘Arctic icecaps’ here mean Arctic sea ice.“‘Next year or the year after, the Arctic will be free of ice’” Lauren Simkins Assistant Professor, University of Virginia: The title is misleading. Wadhams suggests that the central Arctic (only) will be ice free in the summer.

https://science.feedback.org/review/louisiana-flooding-natural-disaster-weather-climate-change-oliver-milman-the-guardian/

1.3

The Guardian, by Oliver Milman, on 2016-08-16.

"Disasters like Louisiana floods will worsen as planet warms, scientists warn"

The article reports on the historic floods that recently occurred in Louisiana and discusses the influence of human-induced climate change on heavy-precipitation events. Overall, the article correctly places this event in its climatic context: science clearly shows one should expect to observe more frequent intense rain events as the planet continues to warm, since it allows the atmosphere to contain more moisture. However, an increase in “flooding” severity related to global warming has not yet been clearly established.See all the scientists’ annotations in contextGUEST COMMENTS: Andrew King Research fellow, University of Melbourne: Overall, the article does a good job of putting the recent heavy rainfalls in Louisiana into the broad context of climate change. While generally we expect to see more heavy downpours as the climate warms, there is a crucial caveat that’s missing- changes in the frequency of some weather systems may mean that for particular locations we wouldn’t see more extreme rainfall events. In the absence of a specific attribution study examining the role of human-induced climate change in this kind of event, we cannot say for certain that climate change increased the likelihood or intensity of these recent rains. This detail is particularly important in places like Louisiana where extreme rainfall events can arise from different weather systems, like hurricanes for example, and there is uncertainty in how climate change is influencing some of these weather events. Michela Biasutti Lamont Associate Research Professor, Lamont Doherty Earth Observatory, Columbia University: This piece gives a pretty standard overview of the state of the science as it pertains to extreme rainfall events and their link to climate: theoretical and model evidence (and, increasingly, observations) suggest that daily extreme precipitation will become more intense, so that high-intensity thresholds will be exceeded more often. The piece is also careful in providing some clarification that this general trend will not necessarily be universal. One possible nuance that might be worth noting is that the link between rainfall and flooding depends heavily on landscape modification as well.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Alexis Berg Research Associate, Harvard University: In my view, this article does a good job reporting on the recent floods in Lousiana and, more generally, the climate-change-induced changes in the water cycle that underlie scientists’ concerns about future increase in floods. However, “heavy rainfall” is not strictly synonymous to “flooding”, and I think it could have provided more context on what is known (or not known) about current, observed changes in floods. Ben Henley Postdoctoral research fellow, University of Melbourne: The article is accurate. The issue of increasing precipitation extremes due to climate change is presented well. Heavy precipitation increases have been observed, and are projected to worsen with climate change. The complexities of ocean-atmosphere circulation changes due to climate change are an area of active scientific research. Increased research in this area will help us answer the public’s questions on the human fingerprint on extreme events. Laurens Bouwer Senior risk advisor, Deltares: The article provides a good representation of the facts, and adds an evaluation of uncertainties, as well as pertinent quotes from experts. Various references to appropriate scientific documentation are provided as well. Further, evidence exists attributing the increase in extreme rainfall to global warming, as summarized in the IPCC 5th report, and more importantly, there is a long line of work attributing changed likelihood of occurrence of single events -like the Louisiana flooding- to climate change (called ‘event attribution’). Both of these topics are not mentioned explicitly, which makes the article quite careful and modest on these issues. James Renwick Professor, Victoria University of Wellington: Very well-written and well-explained article, using the latest scientific understanding. Rasmus Benestad Senior scientist, The Norwegian Meteorological institute: This is an important news report, however, the actual problem is somewhat under-communicated since it mixes return value analysis for a single site with occurrences taking place over many sites. The situation is more dramatic because extreme rains and flooding could happen in many places, and the likelihood for seeing such events is much higher than the probability associated with one specific site. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from Oliver Milman; comments and replies are from the reviewers. 1. As the climate warms due to human activities, the atmosphere can hold more moisture and this is creating more favourable conditions for extreme rain events. “as surface temperatures of the oceans warm up, the immediate response is more water vapor in the atmosphere. We’re in a system inherently capable of producing more floods.” James Renwick Professor, Victoria University of Wellington: Exactly. Every degree C of warming equates to around 7% more water vapor in the air. Not only does this lead to heavier rain, it adds to the warming as water vapor is a potent greenhouse gas. “While the north-east, midwest and upper great plains have experienced a 30% increase in heavy rainfall episodes – considered once-in-every-five year downpours – parts of the west, particularly California, have been parched by drought.” Rasmus Benestad Senior scientist, The Norwegian Meteorological institute: It is expected that an increased greenhouse effect will result in wet areas becoming wetter and dry regions drier because the atmospheric overturning (convection) will respond to the atmospheric opacity [1]. Overturning means air rising in some parts and sinking in others. Rising air (convection) brings moisture aloft where it cools, condenses, forms clouds, and precipitates. The descending air is dry as it is air that previously ascended and where the moisture has precipitated out during the ascent. [1]A mental picture of the greenhouse effect “The contrast in precipitation between wet and dry regions and between wet and dry seasons will increase, although there may be regional exceptions.” Alexis Berg Research Associate, Harvard University: While this picture might provide a leading order approximation, it is mostly valid over the oceans. Over land, recent research has shown that the “wet get wetter, dry get drier” picture does not really apply and things are a little more complex (e.g., see: Byrne and O’Gorman. “The Response of Precipitation Minus Evapotranspiration to Climate Warming: Why the “Wet-Get-Wetter, Dry-Get-Drier” Scaling Does Not Hold over Land” Journal of Climate (2015).) “On Tuesday, the National Oceanic and Atmospheric Administration (Noaa) is set to classify the Louisiana disaster as the eighth flood considered to be a once-in-every-500-years event to have taken place in the US in little over 12 months.” Laurens Bouwer Senior risk advisor, Deltares: This last sentence seems to imply that this is exceptional. However, in a country as large as the USA, it is very well possible to have multiple events each year, that exceed 100 or 500-year frequency thresholds for a particular location. Note that for this case, for multiple locations, the 500-year rainfall amount was exceeded, which is indeed exceptional. Alexis Berg Research Associate, Harvard University: As others pointed out, over a large area like the US, it is not necessarily out of the ordinary to have several places experience rare events – like record floods – in the same year. Further analysis would be required to see if the combination of these events is really unusual. Overall, while there is an observed increase in heavy rainfall event that has been attributed to man-made global warming, changes in floods are more difficult to observe and attribute. The 2012 report on climate extremes from the IPCC indicates that “There is limited to medium evidence available to assess climate-driven observed changes in the magnitude and frequency of floods at regional scales because the available instrumental records of floods at gauge stations are limited in space and time, and because of confounding effects of changes in land use and engineering. […] Further, it points out that, so far, there is “Low confidence that anthropogenic warming has affected the magnitude or frequency of floods at a global scale.” […] So the picture appears complex and uncertain, and while the title of this article is broadly consistent with the last quote above, caution is warranted when interpreting recent flooding events with respect to climate change. For the US in particular, recent research indicates an increase in flooding frequency (but not necessarily magnitude) in the Northern Central US (see Mallakpour and Villarini. “The changing nature of flooding across the central United States.” Nature Climate Change (2015)) “Noaa considers these floods extreme because, based on historical rainfall records, they should be expected to occur only once every 500 years.” James Renwick Professor, Victoria University of Wellington: This means that such a flood is expected to have a 1 in 500 chance of happening in any given year. It does not imply that such event occurs regularly every 500 years though. That statistic would hold if the climate were not warming. Since warming is occurring, and the amount of moisture in the air is increasing, the odds of getting these floods are getting larger/more likely. 2. A record high amount of atmospheric moisture helped generate extreme rainfall levels in Louisiana; in similar situations, other factors (like topography, urban planning, wind patterns…) usually contribute to the magnitude of the resulting flood. “The National Weather Service balloon released in New Orleans on Friday showed near-record levels of atmospheric moisture, prompting the service to state: “We are in record territory.” Emmanuel Vincent Founder & Executive Director, Science Feedback: The chart below from the National Weather Service’s Storm Prediction Center shows that the amount of ‘Precipitable Water’ in the atmosphere over southern Louisiana (Baton Rouge) was unprecedented just before the flood. This flood fits a pattern: a recent study found that most urban flood events over the past 40 years exhibit very high amounts of precipitable water in the atmosphere. see Schroeder et al Insights into Atmospheric Contributors to Urban Flash Flooding across the United States… (2016) Journal of Applied Meteorology and Climatology. 3. An attribution study will be needed before one can properly quantify whether -and by how much- global warming made this particular flood more likely and/or more intense. “While scientists are loathe to attribute any single event to changes in the climate, they state that warming temperatures are helping tip the scales towards altered precipitation. Some, however, bristle at the belief that because floods and storms have always occurred, they should not be linked to climate change” Rasmus Benestad Senior scientist, The Norwegian Meteorological institute: It is true that floods and storms always have occurred, but they have always ocurred for a physical reason. This may be evidence suggesting that these phenomena are rather sensitive to a climate change, if modest natural changes in physical conditions already give rise to variations in the floods and storm activity. We now know that the earth’s atmosphere is changing (increased CO2 and a global warming). It would be naive to think that floods and storms do not change when important factors change while they have always changed in the past. It is also important to think about these concepts in a risk-analysis frame, and it is important to plan for various plausible scenarios. Adam Sobel Professor, Columbia University: Observations over the US and many other places around the world show that heavy rain events have been becoming heavier over the last several decades. Climate models very consistently predict that this should happen as the climate warms, and basic physics leads us to interpret this change as, in large part, a consequence of increasing water vapor in the atmosphere. On this basis we can say that climate change has most likely increased the probability of an event like this. One still can’t say that climate change ’caused’ this event, as each event has many causes and no event can be viewed solely as a consequence of long-term trends. No study can tell us that climate change caused an event like this to happen, full stop. Every weather event has many causes. Climate change is just one of them, and usually not the most immediate. At most it can push things a bit in one direction, making the weather more severe if it was going in that direction anyway. Attribution studies can describe and quantify that push. (more details in this article)

https://science.feedback.org/review/environment-climate-change-records-broken-international-report-oliver-milman-the-guardian/

1.3

The Guardian, by Oliver Milman, on 2016-08-02.

"Environmental records shattered as climate change 'plays out before us'"

The article summarizes the main findings of the “2015 state of the climate” report published by the National Oceanic and Atmospheric Administration. Overall it accurately reports the main findings that many global indicators of the Earth’s climate, notably the global surface temperature, have set new records in 2015 under the joint influence of ongoing human-induced climate change and a strong El Niño event. However, scientists noted a few issues with the article, such as minor errors, a lack of background and references for some key claims and a potentially misleading attribution of Indonesian fires to climate change.See all the scientists’ annotations in contextGUEST COMMENTS: Twila Moon Research Scientist, University of Colorado, Boulder: This article does a good job of summarizing results in the State of the Climate report. However, there are some areas (e.g., Greenland sea level rise contributions and extent of surface melt) where the information is not directly pertinent to modern-day effects of climate change or is presented without context. It is difficult to present so many scientific results regarding climate change in such a short article, and the author doesn’t always succeed at providing the necessary context. Nevertheless, the title clearly conveys the sum total of recent observations, which now show definite fingerprints of climate change in our annual weather.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Keven Roy Research Fellow, Nanyang Technological University: The article did a good job at summarizing the “State of the Climate 2015” report by the AMS. There were few prominent mistakes (the confusion regarding the 90+% of the total extra heat absorbed in the climate system being stored in the oceans stands out) and a few language imprecisions, but overall it conveyed the information and the main conclusions clearly. Victor Venema Scientist, University of Bonn, Germany: The general reader will get a fair impression about the state of the climate in 2015, but the scientifically interested reader will also find several irritating and unnecessary mistakes in details. Jan Lenaerts Assistant Professor, University of Colorado, Boulder: The article is accurate and reflects the report. It is a little vague here and there, but useful for a general audience. Good review of the State of the Climate report. Does appear to conflate climate change with El Niño effects, but at the same time highlights a quote regarding the dual contributions of El Niño and climate change to climate anomalies in 2015. Rasmus Benestad Senior scientist, The Norwegian Meteorological institute: The main picture provided by this report is consistent with the science, although there was a minor mistake (ocean uptake of CO2). Stephan Lewandowsky Professor, University of Bristol: The other commenters have admirably picked up on the slight inaccuracies in the article. I nonetheless believe that a “+2” is in order because the glitches are quite subtle (with the possible exception of confusing 90% of heat with 90% of CO2). On balance, it is very clear that the author tried to convey complex material accurately and this effort was quite successful. Jennifer Francis Senior Scientist, Woods Hole Research Center: The string of records broken and nearly broken in 2015 is stunning, and the story continues into the first half of 2016. Clearly a strong El Niño “juiced” the already disturbed climate system, but the Earth’s behavior in 2015 and recent months may be a preview of a future when global-average warming approaches the 2-degree C level that is generally expected to bring dangerous consequences. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from Oliver Milman; comments and replies are from the reviewers. 1. The average temperature at the surface of the planet shattered previous records in 2015, and 2016 will very likely break this record. While El Niño gave a boost to global temperatures, these records are mostly due to the long-term warming trend. “This means that the world is now 1C warmer than it was in pre-industrial times” Victor Venema Scientist, University of Bonn, Germany: The temperature is 1°C warmer than in the beginning of the instrumental temperature record (1880). The 19th century was likely a little colder than the pre-industrial period. This difference is not large and currently being studied, but likely we did not cross the 1°C warming relative to pre-industrial yet. Global temperature in the Berkeley Earth dataset from 1850 to 2015 “The UN has already said that 2016 is highly likely to break the annual record again, after 14 straight months of extreme heat aided by a hefty El Niño climatic event, a weather event that typically raises temperatures around the world.“ Victor Venema Scientist, University of Bonn, Germany: The influence of El Niño was likely not as large as it was in 1998. A large part of the warming was also in the Arctic, as Jan Lenaerts also argues below. Jan Lenaerts Assistant Professor, University of Colorado, Boulder: I would say that it increases ‘global mean temperature’. An El Niño does not necessarily imply warming everywhere on Earth. Also, especially pronounced are the warm conditions in the Arctic, which are not explicitly mentioned here, but do not relate to the strong El Niño. The first six months of 2016 were the warmest six-month period in NASA’s modern temperature record, which dates back to 1880. Credits: NASA/Goddard Institute for Space Studies 2. Global Sea Level has set a new record in 2015, boosted by melting glaciers around the world and increasing ocean heat content that causes the water to expand. “The thermal expansion of the oceans, compounded by melting glaciers, resulted in the highest global sea level on record in 2015.” Keven Roy Research Fellow, Nanyang Technological University: This statement in the AMS report refers to the satellite altimetry record, which reaches back to 1993. It is also important to remember that it refers to the global average sea level. We do have local records of past sea level that extend further back in time, for instance tide gauge records or inferences based upon biological markers. For instance, combined tide gauge records have been used to infer global mean sea level rise (GMSL) over the 20th century and into the 21st century. The obtained estimate of the GMSL rise agrees with the satellite altimetry record in their overlap since 1993 (e.g., Hay et al., 2015: Probabilistic reanalysis of twentieth-century sea-level rise). “The oceans, which absorb more than 90% of the extra CO2 pumped into the atmosphere“ Rasmus Benestad Senior scientist, The Norwegian Meteorological institute: Here “CO2” should be “heat” … according to the Scripps Institute, the uptake of CO2″ is about 26%. Keven Roy Research Fellow, Nanyang Technological University: “The oceans, which absorb more than 90% of the extra CO2 pumped into the atmosphere” should read “The oceans, which absorb more than 90% of the extra heat pumped into the climate system“. “The world’s alpine glaciers recorded a net annual loss of ice for the 36th consecutive year and the Greenland ice sheet … experienced melting over more than 50% of its surface.” Jan Lenaerts Assistant Professor, University of Colorado, Boulder: That is correct, see figure below: There was an event in the beginning of July when ~50% of the ice sheet experienced melt. This is clearly outside of the expected natural variability, but does not necessarily project the overall Greenland summer (since such melt events are extremely episodic). Overall, Greenland experienced a warm summer, with slightly more surface runoff than average and overall average amounts of snowfall (source) Twila Moon Research Scientist, University of Colorado, Boulder: This is true. Perhaps more important, though, is that surface melt in Greenland started early this year and included several large spikes. While current surface melt is not currently larger than the record-breaking 2012 melt year, it is ahead of 2013-2015 so far. The NSIDC has an excellent summary of current melt status for Greenland here. “Greenland ice sheet … would balloon sea levels by around 7m should it disintegrate” Twila Moon Research Scientist, University of Colorado, Boulder: This is a reasonable number for the total mean sea level rise if all of the Greenland Ice Sheet melted. Total melt of the Greenland Ice Sheet, however, is essentially impossible over the next several hundred years. Nevertheless, the Greenland Ice Sheet has been losing large amounts of ice and the rate of loss has increased over the recent decade or so (references include this paper and this one). The amount of ice Greenland has lost to date has already raised global sea levels and projections indicate the possibility of 0.5 m more sea level rise from Greenland alone over the coming several centuries. 3. While some anomalous climate events of 2015 can be related to climate change with high confidence (eg record low in Arctic sea ice area), such a connection is not established for other events (eg drought in Indonesia). “other “remarkable” changes in 2015 include the Arctic’s lowest maximum sea ice extent in the 37-year satellite record, recorded in February 2015.” Jennifer Francis Senior Scientist, Woods Hole Research Center: The graphs below show a best estimate of ice extent for the period 1850 to 2013 for winter and summer. Source: NSIDC “The rapid changes in the climate may have profound consequences for humans and other species… Severe drought caused food shortages for millions of people in Ethiopia, with a lack of rainfall resulting in “intense and widespread” forest fires in Indonesia that belched out a vast quantity of greenhouse gas” Technically correct, in that drought due to lack of rainfall is linked to Indonesian forest fires in some El Niño years. The lead sentence for the paragraph implies a link between climate change and the following events, including Indonesian forest fires, which is not established. To the extent that climate change might be affecting the frequency and intensity of El Niño events or rainfall patterns during El Niño events, it might be playing a role, but that is not claimed in this article. For example, Dai 2012 (Increasing drought under global warming in observations and models) documents a decreasing observed precipitation trend in Indonesia, but Trenberth, Dai et al 2014 (Global warming and changes in drought) note that “it is probably not possible to determine reliable decadal and longer-term trends in drought without first accounting for the effects of ENSO and the Pacific Decadal Oscillation.” Trenberth, Dai et al also note that drought due to El Niño effects on precipitation may also be exacerbated by the effects of warming on evapotranspiration, which is an area of ongoing study.

https://science.feedback.org/review/science-about-links-between-global-warming-and-massive-heat-waves-chris-mooney-washington-post/

1.7

The Washington Post, by Chris Mooney, on 2016-07-21.

"What science can tell us about the links between global warming and massive heat waves"

The Washington Post reports on the “massive heat wave” that is currently affecting the US and explores the question of how such events are related to human-induced global warming. The scientists who have reviewed the article confirm that it accurately describes the state of scientific knowledge on the topic. While the observed increased frequency, severity and duration of heat waves in some parts of the world are among the most certain impacts of climate change, calculating any increases to the current heat wave’s probability or intensity as a result of global warming will require a specific study (called an “event attribution study”), which has not yet been performed for the current event as of July 25th.See all the scientists’ annotations in contextGUEST COMMENTS: Andrew King Research fellow, University of Melbourne: This is a well-written article that provides a good overall discussion around the connection between climate change and the ongoing US heat wave. In the absence of a specific event attribution study the role of climate change in this event can’t be quantified, but Chris Mooney provides an insightful overview of the role of climate change in heat events generally. Friederike Otto Deputy Director Environmental Change Institute, University of Oxford: I do not find anything wrong with the article. And it makes the key point that robust event attribution is now possible. However, the article could better help readers understand what ‘event attribution’ is in contrast to ‘predictions’. The article makes the point that it is now possible to attribute individual classes of extreme events to climate change: eg heat waves in a specific region and season. It is not clear in pointing out that the reason for having to do a specific ‘attribution study’ is to quantify the role anthropogenic climate change played in an event given the observed class of heat wave. While on average we see an increase in heat wave frequency and intensity, there are parts of the world where there is actually hardly any increase (e.g. parts of India in the pre monsoon season) while for others the likelihood of certain types of heat waves to occur has increased at least 10 fold (eg Central Europe).REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Geert Jan van Oldenborgh Senior researcher, KNMI (The Royal Netherlands Meteorological Institute): The article gives a fair and balanced view on the topic. The one proviso that is not made that could have been added is that increasing air pollution with aerosols that block sunlight can counteract the effect of greenhouse gases on heat waves, as was the case in Europe up to the mid-1980s and is the case now in some other parts of the world such as India. However, the opposite is happening in the United States where clearer skies also increase the risk of severe heat waves. There are other factors, such as drying soils, that can exacerbate a heat wave, so indeed a specific study is needed to know how much the present heat wave can be attributed to global warming. Ken Caldeira Senior Scientist, Carnegie Institution for Science: This article is very good because it relies on quality documents including a National Academies report and the US Climate Assessment. It quotes several scientists who reflect the broad consensus of scientists who work on extreme event attribution. The story makes the point that with global warming, extreme heat waves will become more common and more intense, yet just as you cannot say with 100% confidence that a smoker would not have died of cancer had he not smoked, we cannot with 100% confidence attribute any particular heat wave to climate change. However, just as statistics, combined with mechanistic understanding, clearly demonstrate that smoking cigarettes causes cancer, statistics, combined with a mechanistic understanding of climate physics, clearly demonstrate that the accumulation of greenhouse gases in the atmosphere is causing an increase in the frequency and intensity of heat waves. Overall, an excellent article. Twila Moon Research Scientist, University of Colorado, Boulder: This well-explained article accurately represents the current science for understanding the contribution of climate change to extreme events such as heat waves. Victor Venema Scientist, University of Bonn, Germany: A fair summary of the scientific current understanding of the observed increases in heat waves and their relations with global warming. Doug Smith Senior researcher, UK Met Office: A balanced overview. Sarah Perkins-Kirkpatrick Research Scientist, Climate Change Research Centre, The University of New South Wales: This article is very accurate, a little oversimplified in some areas, but that can be difficult to overcome. Patrick Grenier Specialist in climate scenarios, Ouranos: The journalist is right regarding his main point: it cannot be told that global warming is the cause of a specific extreme event (unless it could not have existed without global warming); the issue must be addressed with probabilities, comparing all events we experience with all events we would have got without global warming. However, the point is not well illustrated by the current heat wave in Eastern US, since this region is precisely known for showing negative long-term trends in many extreme heat indicators. In summary, the main point is insightful and applies globally, but the journalist does not illustrate it with the most appropriate event, because projected increases in the indicators of extreme heat over Eastern US have not clearly got out of the natural variability so far. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time.Key Take-aways : The statements quoted below are from Chris Mooney; comments and replies are from the reviewers. 1. Heat waves in the U.S. have already become more frequent and intense due to human induced global warming. “And the gist is that when it comes to extreme heat waves in general — heat waves that appear out of the norm in some way, for instance in their intensity, frequency, or duration — while scientists never say individual events are “caused” by climate change, they are getting less and less circumspect about making some connection.” Andrew King Research fellow, University of Melbourne: This is certainly true. Over the last few years we’ve seen more and more attribution statements related to heat waves (where there is higher confidence in the climate change link compared with other extremes, such as heavy rain events) and scientists have become more confident in making this connection. Rasmus Benestad Senior scientist, The Norwegian Meteorological institute: “Climate change” is by definition a shift in the weather statistics, such as the curve that describes the likelihood of temperatures exceeding a certain threshold [see figure below]. The temperature has a statistical character that is close to being bell-shaped (normal distribution), which implies that high temperatures are expected to be more frequent with a global warming – unless the typical range of temperatures (standard deviation) or shape of the curve changes as well. Climate is the typical character outlined by this curve (probability density function) describing the probabilities, whereas weather is each different data point on which this curve is based. When referring to one event – one data point – one talks about weather. Weather is not the same as climate, but they are related: climate is the expected weather. Figure illustrating how a change in climate influences the frequency of extreme heat events: an increase in the average temperature (upper panel) causes a large increase in the probability of extreme hot events; a change in the climate variability (lower panels) can further alter the frequency of extreme events. – adapted from IPCC report (2001) “The U.S. National Climate Assessment found that U.S. heat waves have already “become more frequent and intense,” that the U.S. is shattering high temperature records far more frequently than it is shattering low temperature records (just as you’d expect), and that it is seeing correspondingly fewer cold spells.” Andrew King Research fellow, University of Melbourne: This is true and is also consistent with findings from other areas of the world. For example, Dr Sophie Lewis led work that showed in Australia there have been 12 times as many hot records compared to cold records since 2000. 2. In order to calculate how much climate change has exacerbated a given heat wave (or made it more likely), an event attribution study is needed; such a study has not yet been completed for the current heat wave. “Typically, in such an attribution study, scientists will use sets of climate models — one set including the factors that drive human global warming and the other including purely “natural” factors — and see if an event like the one in question is more likely to occur in the first set of models. Researchers are getting better and better at performing these kinds of studies fast, in near real time.” Andrew King Research fellow, University of Melbourne: This is an accurate description of how extreme event attribution studies are conducted. 3. Heat waves cause severe risks to health, particularly for children and elderly people. Some deaths due to heat waves can be directly attributed to climate change. “this event poses severe risks to health — particularly for children and the elderly […] an extreme 2003 heat wave that affected Paris and Europe, and which has indeed been connected to climate change through statistical attribution analysis […] killed hundreds of people in Paris and London, and a recent study attributed at least some of those deaths, themselves, to climate change.” Victor Venema Scientist, University of Bonn, Germany: Only mentioning the deaths in two cities understates the danger of heat waves. The number of people who died in the 2003 heat wave is estimated to be in the tens of thousands. This article estimates it was 70 thousand additional deaths. Kristie Ebi Professor, University of Washington: The majority of injuries, illnesses, and deaths during heatwaves are preventable. A robust literature base documents individuals at higher risk during heatwaves, such as adults over the age of 65 years, infants, individuals with certain chronic diseases, and others. Heatwave early warning and response systems save lives; expanding these systems to more cities and increasing awareness of the health risks of high ambient temperatures could increase resilience as heatwaves increase in frequency, intensity, and duration. Another issue is that growing confidence that climate change is increasing the probability of heatwaves means some deaths during heatwaves could be attributed to climate change. Sarah Perkins-Kirkpatrick Research Scientist, Climate Change Research Centre, The University of New South Wales: When the 2003 European heatwave occurred it killed 70 000 people. At the time the likelihood of that event occurring had doubled due to human influence. Now an event like this is 10 times more likely due to human influence. References: Stott et al (2004) Human contribution to the European heatwave of 2003. Nature. Christidis et al (2015) Dramatically increasing chance of extremely hot summers since the 2003 European heatwave. Nature Climate Change. Trigo et al (2005) How exceptional was the early August 2003 heatwave in France?. Geophysical Research Letters.

https://science.feedback.org/review/heat-waves-u-s-already-become-frequent-intense-due-global-warming/

Accurate

The Washington Post, Chris Mooney, 2016-07-21

the U.S. is shattering high temperature records far more frequently than it is shattering low temperature records

Because of human-caused global warming, heat waves in the U.S. are becoming more common and the hottest heat waves are getting hotter. Weather is naturally variable, but the trend of warming temperatures means that local record highs are set more often, and record lows less often.

The U.S. National Climate Assessment found that U.S. heat waves have already 'become more frequent and intense,' that the U.S. is shattering high temperature records far more frequently than it is shattering low temperature records (just as you’d expect), and that it is seeing correspondingly fewer cold spells.

Andrew King Research fellow, University of Melbourne: This is true and is also consistent with findings from other areas of the world. For example, Dr Sophie Lewis led work* that showed in Australia there have been 12 times as many hot records compared to cold records since 2000. Lewis and King (2015) Dramatically increased rate of observed hot record breaking in recent Australian temperatures, Geophysical Research LettersRasmus Benestad Senior scientist, The Norwegian Meteorological institute: “Climate change” is by definition a shift in the weather statistics, such as the curve that describes the likelihood of temperatures exceeding a certain threshold [see figure below]. The temperature has a statistical character that is close to being bell-shaped (normal distribution), which implies that high temperatures are expected to be more frequent with a global warming – unless the typical range of temperatures (standard deviation) or shape of the curve changes as well. Climate is the typical character outlined by this curve (probability density function) describing the probabilities, whereas weather is each different data point on which this curve is based. When referring to one event – one data point – one talks about weather. Weather is not the same as climate, but they are related: climate is the expected weather. Figure illustrating how a change in climate influences the frequency of extreme heat events: an increase in the average temperature (upper panel) causes a large increase in the probability of extreme hot events; a change in the climate variability (lower panels) can further alter the frequency of extreme events. – adapted from IPCC report (2001)Sarah Perkins-Kirkpatrick Research Scientist, Climate Change Research Centre, The University of New South Wales: This is certainly true—the distribution of temperature is shifting towards warmer conditions. This allows for a large increase in the frequency of heatwaves, as well as an increase in their intensity. But the amount of change depends largely on the area of focus. Some regions have a much wider temperature distribution than others. Changes in the variability of the temperature distribution will also influence by how much extreme events like heatwaves will change. Almost all attribution studies on extreme heat conditions have come back with some measurable human influence. The amount of this influence varies a lot, and therefore, is specific to the event analysed. But in general, yes, there is a detectable human influence behind extreme hot temperature events.

https://science.feedback.org/review/climate-change-emergency-jet-stream-shift-warning-global-warming-extreme-weather-gabriel-samuels-the-independent/

-1.4

The Independent, by Gabriel Samuels, on 2016-06-30.

"Scientists warn 'global climate emergency' over shifting jet stream"

The article repeats claims made by two bloggers that upper-level winds crossing the equator would be an unprecedented consequence of climate change. In reality, such wind features are frequently observed and the central claim of the article is thus unsupported by science. Note: The Independent has updated the article on July 1st, by: changing the subtitle of the article from the initial “Experts say drastic weather changes could cause ‘massive hits to food supply’ and ‘death of winter’” to “Other scientists have since dismissed the claims as ‘total nonsense’”; adding a sentence linking to a rebuttal of the claims that reads “However other scientists dismissed their claims, with one describing their concern over wind crossing the equator as “total nonsense”.” Unfortunately the original inaccurate article has been shared 10k times on social media while the correction has only been shared 150 times (as of July 5th 2016).See all the scientists’ annotations in contextGUEST COMMENTS: Edwin Gerber Associate Professor, New York University: This article makes little sense. It uses scientific jargon, such as in the last paragraph, to make it sound “scientific”, but uses it so loosely that it has no meaning. I do not see any logic behind these wild claims, there are no connections with established research, and there is no discussion of statistical certainty. Moreover, wild attributions to anthropogenic climate change are made without any backing. Winds routinely cross the equator in the monsoonal circulations. This happens every year, without any grave consequences for climate.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Tim Woollings Lecturer, University of Oxford: The article seems to truthfully repeat the bloggers claims, but with no attempt to verify these claims from other sources. Unfortunately the claims are ridiculous. This snapshot is clearly just a weather pattern, rather than any long-term change. To put things in context, we do expect the jet streams to move in response to climate change, but only by a couple of degrees of latitude over the coming century. Emmanuel M Vincent Research Scientist, University of California, Merced: This article reports on speculations made by bloggers without any appropriate fact-checking. Had the journalist contacted actual scientists, it would have been easy for him to understand that the claims are without any scientific substance. One can only wonder whether this lack of fact-checking is intentional to create a click-bait headline and generate buzz on social media. Jennifer Francis Senior Scientist, Woods Hole Research Center: It is true that there are often (but not always) two jet streams in each hemisphere. The hypothesis related to Arctic warming causing weaker zonal winds of the jet refers to the POLAR jet. This flow is driven primarily by the temperature difference between the Arctic and middle-latitudes. The features headlined in this story, however, are a product of the SUB-TROPICAL jet, which is driven mainly by temperature differences between the tropics and middle-latitudes. The upper-level tropical atmosphere is also warming faster than most other places, which is increasing the temperature difference and thus contributing to a STRONGER sub-tropical jet [and not a weaker, wavier jet as this article suggests]. Clifford Mass, Professor of Atmospheric Sciences, University of Washington: This is total nonsense. Flow often crosses the equator. The cross-equator flow identified by Scribbler and Beckwith is not between mid-latitude jet streams, as claimed. The analysis is making mistakes that even one of my junior undergrads would not make. [this comment was originally published in a rebuttal to the bloggers’ claims in The Washington Post] Ken Caldeira Senior Scientist, Carnegie Institution for Science: This is an odd story because the subhead and the second quotes dismiss the central claim as being “total nonsense”. So, the story seems more-or-less accurate: “A couple of people make a strong claim that is likely to prove false and a bunch of other people denounce the claim as total nonsense”. The question therefore is not so much the accuracy of the story, but of the editorial decision to publicize something that was likely to prove total nonsense. Further, the story reports on a blog post. I do not see any reference to any peer-reviewed paper. So again, the question is why is The Independent giving so much play to what appears to be an erroneous blog post? I do not see this piece so much as a failure of reporting as a failure of proper editorial control. [note that this comment was written after the article was updated with a link to the rebuttal]Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time.

https://science.feedback.org/review/its-official-humans-are-making-the-earth-much-greener-washington-post-chris-mooney/

0.6

The Washington Post, by Chris Mooney, on 2016-06-27.

"Thanks to climate change, the Arctic is turning green"

Overall the article accurately reports that increased temperatures and atmospheric CO2, due to human greenhouse gas emissions, are already increasing plant growth in the Arctic region. However, scientists point to some misleading aspects of the article: most problematically, the author leaves open the hypothesis that the increased CO2 uptake by plants in the Arctic could significantly offset future global warming. In reality, scientists already take into account CO2 uptake by plants in climate projections and conclude that Arctic greening is very unlikely to have a significant impact on the global carbon cycle.See all the scientists’ annotations in contextGUEST COMMENTS: Chelsea Little PhD candidate, Eawag, The Swiss Federal Institute for Aquatic Science and Technology: The main message of this article – that the Arctic is greening, and that this trend is caused by anthropogenic climate change – is accurate and well-explained. The author also addresses the complexity of the trend’s potential impacts on the Arctic itself and on global greenhouse gas concentrations. Peter Reich Regents Professor, University of Minnesota: The article is a poster child for a lot of what is wrong with even our “hypothetically” best mainstream press coverage of science and the environment. The article is factually accurate (up to a point) but incomplete. It is true that rising CO2 and longer growing seasons likely will increase LAI [leaf area index] and productivity in certain northern regions, but the article gives the impression (by intentionally or unintentionally conflating northern regions and the rest of the world) that this may be widespread. Additionally, and equally or more problematically, the article is imbalanced in not fully acknowledging that the scale of net positive impacts (in terms of increased carbon gain) in far northern regions will likely only partially offset: carbon losses from high latitude ecosystems (e.g. soil carbon losses from peatlands and permafrost due to decomposition, respiration and/or fire), climate-change induced losses of productivity in the tropics, and climate-change induced losses of carbon from increased wildfires in southern boreal and temperate coniferous forests. Thus the article fails my “objectivity” test in being more about making a news splash than about reporting these important findings accurately framed within the overall broader context.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Ken Caldeira Senior Scientist, Carnegie Institution for Science: Overall, this is an excellent article. It not only reports the key scientific findings but also highlights several key uncertainties. This article nicely balances a description of what we think we know with a description of what we know we don’t know. Overall, I would consider this an exemplary piece of science journalism. My one critique would be the assumption implicit in the reporting that greening is all good. While greening is good for some things, greening can be disruptive to ecosystems. Organisms that were well-adapted to harsher conditions might find themselves at an ecological disadvantage as conditions ameliorate, and thus there will be winners and losers. Thus greening can have adverse consequences for biodiversity. This implicit assumption that greening is good is reflected in the title of the piece, raising the issue of who or what we should ‘thank’ for the greening. Overall, however, this is a thoughtful and nuanced piece of scientific reporting. Jake Weltzin Program Manager, US Geological Survey: Overall a nice description of the state of the science; well-referenced and linked; outlines the uncertainties; describes how this work builds on, but is different from, prior work. Alexis Berg Research Associate, Harvard University: This article reports on a new high-profile study that formally attributes the documented greening of the Arctic to human greenhouse gas emissions. The article correctly places this new research in its context (the greening had been observed before, but not explained) and identifies what is new in the study. However, the author then goes on to discuss the implications of this greening for the carbon cycle, and somehow implies that these results about Arctic greening are new cause for optimism, as greening will be associated with CO2 absorption by the land which will slow down global warming. This whole discussion, in my view, was confused and potentially misleading for readers. The distinction between “greening” and ecosystems being a potential sink/source of carbon is not well presented. Arctic greening is well documented, but whether this means the Arctic is storing more and more carbon (and will keep doing so in the future) is unclear, and a topic of ongoing research. The article also seems to imply that these results are new cause for optimism because the land carbon uptake was somehow not accounted for in climate projections. This is incorrect. It is already well established that the land takes up about 25% of our CO2 emissions. Observations of greening at high latitudes are consistent with our expectations. The land carbon sink is already accounted for in climate change projections. There are some uncertainties, but the issue is mostly whether this sink will persist or decrease – not, as the author implies here, whether it will somehow go up to offset the entirety of human CO2 emissions and associated global warming. The article reports about recent evidence that terrestrial ecosystems are ‘greening’ in response to human activities, principally the increasing atmospheric CO2 concentration. The author presents this ‘greening’ as a new finding while annual global carbon budgets have reported that about 25% of the fossil-fuel emissions have been taken up by the biosphere since the 1960s. Nothing is fundamentally wrong in the article but it is organized in a somewhat misleading way, with a high risk that the title could be taken out of context by “skeptics”. James Renwick Professor, Victoria University of Wellington: This is a very nice article that lays out the recent evidence. It discusses the pluses and minuses of the issue and comes to a balanced conclusion. The article is quite neutral and balanced. It describes the Arctic greening and its attribution to climate change and CO2 increase, also mentioning uncertainties. The article concludes by saying that “researchers do not seem to be arguing that it’s enough to counterbalance the entire human-induced warming trend”. On the contrary, this should be seen as evidence that “we are causing the Earth to change”. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The statements quoted below are from Chris Mooney; comments and replies are from the reviewers. 1. Increased CO2 concentrations and temperature won’t necessarily increase plant productivity in the future and in all regions (there are other factors controlling plant growth such as nutrient and water availability…) “Earlier this month, NASA scientists provided a visualization of a startling climate change trend — the Earth is getting greener, as viewed from space, especially in its rapidly warming northern regions. And this is presumably occurring as more carbon dioxide in the air, along with warmer temperatures and longer growing seasons, makes plants very, very happy.” Peter Reich Regents Professor, University of Minnesota: The point in the second sentence may be true for areas where longer growing seasons and warmer temperatures do increase productivity, but it is likely false for vast other regions of the world where lack of moisture will outweigh positive impacts of global change on growth. So this sentence right off the bat gives a bit of a misrepresentation by being worded in a way that can be construed as applying globally not just in the far north. Also there is nothing “startling” about this trend – it is exactly as hypothesized for such regions. “This is happening even as the overall warming of the planet may, by lengthening growing seasons and moistening the atmosphere, further stoke plant growth.” Alexis Berg Research Associate, Harvard University: … note that relative humidity over land, near the surface, is projected to decrease with global warming (i.e., humidity increases more slowly than temperature over land). This has been observed in the past 10-15 years (although the role of variability is still unclear). So “moistening of the atmosphere”, as far as vegetation is concerned, is not accurate (at least globally). See: https://www.climate.gov/news-features/understanding-climate/2013-state-climate-humidity “The key question then becomes how much this process can offset overall global warming over time. And that’s quite unclear. “ James Renwick Professor, Victoria University of Wellington: Exactly. While the “greening” via extra plant growth could help put a brake on climate change, it depends on plants having enough water, and temperatures they thrive in. Neither of these are guaranteed in future, and the greening could easily become browning as the years pass. The overall effect on atmospheric concentrations of CO2 is likely to be small. “He said he is not sure to what extent the greening trend will continue, as “disturbances” like wildfires might counteract it, or plants may become “acclimated to this kind of high temperature”” The Duke FACE [free-air CO2 enrichment] experiment also showed that it is not clear whether nutrient availability will continue supporting high rates of plant productivity despite higher atmospheric CO2 concentrations. 2. Arctic greening won’t offset much of global warming. The global carbon uptake by biomass (plants) is a well-known carbon sink and it is unclear yet whether this sink will remain effective in the future. “It is clear, then, that greening is emerging as a factor with the potential to blunt some of the worst impacts of human greenhouse gas emissions.” Chelsea Little PhD candidate, Eawag, The Swiss Federal Institute for Aquatic Science and Technology: In fact, experts agree that the greening of the arctic is unlikely to even offset the increased carbon release from the arctic itself (much less the rest of the world) in a changing climate, for instance by permafrost melting: The figure above is from a 2016 study that was authored by 100 expert researchers in various fields of arctic climate research, which concludes: “Our study highlights that Arctic and boreal biomass should not be counted on to offset permafrost carbon release and suggests that the permafrost region will become a carbon source to the atmosphere by 2100 regardless of warming scenario.” “Still, the trend is already prompting more optimistic assessments of our climate future in some quarters. Arctic greening was recently cited, in a major report by the U.S. Geological Survey, as the central reason that the state of Alaska, despite worsening wildfires and more thaw of permafrost, might still be able to stow away more carbon than it loses over the course of the 21st century.” Alexis Berg Research Associate, Harvard University: a) This is highly uncertain, because, as discussed, the future of the greening trend is unclear b) it is only for Alaska, and is unlikely to make a significant difference for “our climate future” as the author mentions. c) even if it could be generalized to the entire Arctic, or the entire land, it is no cause for “optimism”: as discussed above, the land is already a carbon sink. It might remain one in the future, despite climate change, but the risk is actually that it decreases and leaves us with more of our emissions accumulating in the atmosphere. “climate change skeptics and contrarians … have long contended that global warming won’t be all bad, and that plants might help offset any global warming trend.” It is not only a skeptic’s argument: the land biosphere does offset part of the warming by taking up 25% of emissions. However, the uncertainty in the durability of this pattern is very large with no clear consensus between earth system models used in the IPCC latest assessment report, see Figure below: From Friedlingstein et al (2014) Uncertainties in CMIP5 Climate Projections due to Carbon Cycle Feedbacks, Journal of Climate “But thus far, researchers do not seem to be arguing that it’s enough to counterbalance the entire human-induced warming trend.” Alexis Berg Research Associate, Harvard University: Of course not. This sentence is highly misleading. As indicated above, the land carbon sink is a well-established phenomenon, not a new theory based on new observations related to Arctic greening and that somehow scientists would now be debating to know whether it will offset global warming entirely. Nobody is even talking about that. The issue is whether the current carbon sink (25% of our emissions) will maintain itself or decrease. The “land sink” offsets about 25% of fossil-fuel emissions annually*. The long-term durability of the sink is debatable as it may be threatened by simultaneous enhancements of soil respiration due to warmer temperatures and more substrate availability (permafrost thaw in particular) but with a large climate-driven variability. *data source: www.globalcarbonproject.org Jacqueline Mohan, Associate Professor, University of Georgia In terms of ecosystems being a carbon sink/storage or source to the atmosphere, it is essential we consider soils and soil microbes. The majority of Arctic ecosystem carbon is stored in the SOILS. With enhanced plant productivity, there is more “microbial food” in the form of organic carbon from plants going to the soils. More microbial food means more microbial metabolism/decomposition of organic carbon to CO2, which is an important SOURCE of carbon (CO2) to the atmosphere with a climate warming effect. To understand what is going on with Arctic ecosystem-climate interactions, we need to know what is going on with ecosystem respiration (C source to atmosphere) not just productivity (C sink from the atmosphere and the topic of the article on increasing “greeness”). In ecosystem ecology there is a finding of a “priming” effect on soil microbial C decomposition, where a small amount of yummy, labile C (the new green stuff coming from plants) can stimulate the decomposition and release to the atmosphere of very old, less yummy recalcitrant forms of C that had been stored in soils for a long time. This could actually result in more carbon being released to the atmosphere by Arctic ecosystems than they took from the atmosphere to support the measured enhancement in greenness. 3. The fact that the Arctic is “greening” has been documented before, but the attribution of this trend to human activities is new. “new research in Nature Climate Change not only reinforces the reality of this trend — which is already provoking debate about the overall climate consequences of a warming Arctic — but statistically attributes it to human causes, which largely means greenhouse gas emissions (albeit with a mix of other elements as well).” Alexis Berg Research Associate, Harvard University: That’s a good summary of what’s new in this study: Arctic greening had been documented before, its causes had been discussed, but this is the first study to formally attribute this greening trend to human gas emissions. Note that trends in surface temperature and in some aspects of the hydrological cycle (e.g., precipitation, evaporation) have been detected and attributed similarly; this is the first study to do so with vegetation trends (which appear closely related to temperature trends, though). Chelsea Little PhD candidate, Eawag, The Swiss Federal Institute for Aquatic Science and Technology: While the NASA project is a wonderful visualization with impressive details and scale, the trend of Arctic greening is not startling to scientists. Researchers have been studying the increase in plant growth in the arctic for well over two decades at this point. The author notes this later in his article, but framing the pattern as surprising for the lede is somewhat disingenuous. Whether the trend is slowing or reversing itself, why some areas are browning rather than greening, or what the long-term consequences might be are still very much debated, but the pattern itself is extremely well-established. Here is some of the previous work detailing the trend: “Increased plant growth in the northern high latitudes from 1981 to 1991” R. B. Myeni et al, “Greening of arctic Alaska, 1981-2001” Gensuo Jia et al “Vegetation greening in the canadian arctic related to decadal warming“, by the same authors also using satellite data, this time from 1982-2006 “Divergent Arctic-Boreal Vegetation Changes between North America and Eurasia over the Past 30 Years“, Jian Bi et al, showing greening also in the European and Russian Arctic

https://science.feedback.org/review/great-barrier-reef-perish-2030s-andrew-freedman-mashable/

1.0

Mashable, by Andrew Freedman, on 2016-04-29.

"Great Barrier Reef may perish by 2030s..."

This Mashable article reports on preliminary research that finds that the ongoing coral bleaching event in the Pacific is mainly due to human-caused global warming, and that if global warming proceeds as currently expected, “large parts” of the Great Barrier Reef could die by the mid-2030s. Six scientists have reviewed the article and conclude that overall it is accurate and in agreement with the science. The title, however, was pointed out to be somewhat exaggerated. Scientists expect that coral reefs may perish by the 2030s, yet the “Great Barrier Reef” is an ecosystem of many different species that are variously resilient to climate change. To be clear, catastrophic impacts are predicted for coral reefs, but this does not necessarily mean the entire Great Barrier Reef will be devastated. See all the scientists’ annotations in contextGUEST COMMENTS: The article reflects the current state of knowledge in this area. While it may sound alarming (even alarmist) that the world’s most biologically diverse marine ecosystem may be largely eliminated over the next 20-30 years, this is the conclusion and scientific consensus to be found in Chapter 30 and other places of the latest Intergovernmental Panel on Climate Change report (IPCC). It is also the consensus conclusion of the major scientific bodies and science community that study coral reefs (e.g. International Society for Reef Studies report). Jon Day PhD candidate, ARC Centre of Excellence for Coral Reef Studies, James Cook University: The article focuses solely on increasing ocean temperatures whereas the Great Barrier Reef (GBR) is currently threatened by multiple pressures – however, none of the other pressures are mentioned. It builds on the erroneous headline that “..93% of the GBR has already been devastated by bleaching” – whereas the media release from the ARC Centre for Coral Reef Studies explained why this was not a true summation of the recent bleaching situation. This article also gives readers the (false) impression that the entire Great Barrier Reef will be devastated within decades; whereas the article should have clarified it was referring to the coral reefs which, whilst a critical part of the GBR, comprise around 10% of the entire area.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. The article is an accurate description of an unpublished study that models the effect of anthropogenic ocean warming on ocean temperatures and coral bleaching. It is a nice description of the science, context, warming impacts, and basic ecology of the system. Minor points off for a somewhat exaggerated headline. (Note, the faculty are at three academic research institutions in Australia, not at the ARC, which is the national funding agency). James Renwick Professor, Victoria University of Wellington: This is a very good and readable article. I can find very little to quibble with over the description of the science. Excellent science, communicated clearly. Sarah Perkins-Kirkpatrick Research Scientist, Climate Change Research Centre, The University of New South Wales: I was an author on the scientific study this article is reporting on. The article is sticking to our findings very accurately. It also does a nice job of presenting the state of knowledge in the field.Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time.Key Take-aways : The statements quoted below are from Andrew Freedman; comments and replies are from the reviewers. 1. Coral reefs around the globe are threatened with extinction this century due to climate change that causes the oceans to warm and become more acidic “The projection that much of the Great Barrier Reef could perish within the next few decades could turn out to be too pessimistic, since other research has shown that some species of corals are surprisingly resilient to the stress from changing ocean temperatures.” Ken Caldeira Senior Scientist, Carnegie Institution for Science: Whether it is two decades or four decades does not make much of a difference to people living 100 years from now. It is clear that if we do not curtail emissions dramatically and soon, coral reefs around the world will be gone. I would like to add to Ken’s point here. We are already – and have been for some time – into dangerous climate change when it comes to coral reefs and hundreds of millions of people that depend on them. The first global mass coral bleaching (NB: reef scale and regional coral bleaching has been reported since the early 1980s and not before) occurred in 1998 and saw the death of an estimated 16% of reef building corals from across the planet (which sounds small until you appreciate that this is a global average!). While it is too early to speculate at this point, the fact that we now have much warmer seas underpinning the current global disturbance to temperature patterns (plus the much more severe event in Australia) suggests that we will have a much greater mortality at the end of 2016 than what we saw in 1998. “The analysis’ findings dovetail with other research that has predicted the mass die-off of coral reefs around the planet by the year 2050, as waters warm and exceed the tolerance level of many coral reef systems.” This is true. This statement refers to the study I published in 1999 (Climate change, coral bleaching and the future of the world’s coral reefs) which brought climate projections together with the known tolerances of reef building corals and specifically proposed that the conditions that cause serious bleaching today would occur every 1-2 years by 2040-2050.[…] The important point here is that anything more frequent than 10-15 years in terms of mass coral bleaching events will overwhelm regeneration, which normally takes this long to occur. That is, coral reefs go downhill well before bleaching conditions become as frequent as every 1-2 years. “a new study by scientists at the Australian Research Council finds that the ongoing bleaching event is mainly due to human-caused global warming, and that if global warming proceeds as currently expected, “large parts” of the Great Barrier Reef could die by the mid-2030s.” Ken Caldeira Senior Scientist, Carnegie Institution for Science: We published a paper some years ago projecting that by mid-century, no coral reefs would be sustainable (Silverman et al 2009: Coral reefs may start dissolving when atmospheric CO2 doubles). It is thus not surprising to see the failure of large areas of reef before that date. “Great Barrier Reef may perish by 2030s” Ken Caldeira Senior Scientist, Carnegie Institution for Science: This word ‘may’ is obviously key. The question is: what is the likelihood. 2. The current global bleaching event is unprecedented; it is due to the combined influence of global warming and El Niño “The ongoing global bleaching event is the longest-lasting one ever observed, and only the third ever seen. It has occurred during the warmest year on record, which occurred in 2015, and the two most unusually mild months on Earth, which took place in January and February, respectively.” It should be emphasized to the readers that mass coral bleaching first turns up in scientific records in the early 1980s – with no reports prior to that. Over time, mass coral bleaching and mortality has expanded in frequency and severity, with three truly global events being recorded so far – 1998, 2010, and 2016. The apparent shortening of the interval between global events is of great concern and suggests that anything we can do now to avoid further increases in carbon dioxide and other greenhouse gases in the atmosphere will save very substantial amounts in lost income and livelihoods from subsistence as well as industries such as fishing and tourism. This is an issue of food security – the effects of which are already occurring and which are growing more serious by the day. 3. Ocean warming is one of many human pressures that are stressing coral reefs (eg pollution, acidification…) “Australia’s Great Barrier Reef is one of the world’s greatest reservoirs of biodiversity. A World Heritage site, it is currently under assault from unusually hot ocean temperatures,” Jon Day PhD candidate, ARC Centre of Excellence for Coral Reef Studies, James Cook University: The 2014 Outlook Report published by Great Barrier Reef Marine Park Authority, the agency responsible for managing the Great Barrier Reef (GBR), clarifies that the GBR is currently faced with many pressures, of which climate change is only one. Poor water quality from land-based runoff, damage from cyclones, ocean acidification, Crown-of-Thorns starfish, dumping of dredge spoil, etc, are among a multitude of pressures which are cumulatively impacting on the GBR, and particularly upon coral reefs. Ken Caldeira Senior Scientist, Carnegie Institution for Science: Note that there is also a possibility that ocean acidification is contributing stress to coral reef systems, making them more susceptible to bleaching from high seawater temperatures. Note: The article builds on another Mashable article (“Coral bleaching has devastated 93% of the Great Barrier Reef”) whose title is misleading “Coral bleaching has devastated 93% of the Great Barrier Reef” Jon Day PhD candidate, ARC Centre of Excellence for Coral Reef Studies, James Cook University: This headline stating that “bleaching has devastated 93% of the GBR” is misleading as I explained in a recent article in The Conversation: “It is important to recognise that if bleaching was observed on a reef, this does not mean a particular reef has entirely bleached. […] Perhaps the more accurate way to frame the results (and indeed the wording used in the media release) is to say that only 7% of the coral reefs across the Great Barrier Reef have completely avoided bleaching.”

https://science.feedback.org/review/bjorn-lomborg-overheated-climate-alarm-wall-street-journal/

-1.3

The Wall Street Journal, by Bjorn Lomborg, on 2016-04-06.

"An Overheated Climate Alarm"

On 4 April 2016 the US Global Change Research Program released a comprehensive overview of the impact of climate change on American public health. In an op-ed in the Wall Street Journal, Bjorn Lomborg criticizes the report as unbalanced. Ten scientists analyzed the article and found that Lomborg had reached his conclusions through cherry-picking from a small subset of the evidence, misrepresenting the results of existing studies, and relying on flawed reasoning.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Aaron Bernstein Associate Director of the Center for Health and the Global Environment, Boston Children’s Hospital, Harvard: While it’s true that cold may kill more people today than heat, Lomborg’s assertion that climate change will result in fewer overall deaths in the U.S. this century from extreme temperatures is not supported by available evidence. The citations in the report, which Lomborg himself dismisses, substantiate this claim e.g. Mills, David, et al. “Climate change impacts on extreme temperature mortality in select metropolitan areas in the United States” in Climatic Change. Lomborg largely conflates U.S. with global assessments. His logic, from a public health perspective, is also deeply troubling and fails, at first pass, the maxim of “first do no harm”. Beyond this, adaptive capacity to climate extremes is no easy feat and as several past extreme heat events have shown, such as the European heatwaves of 2003 or 2010, the consequences reverberate beyond mortality in those directly exposed. Heatwaves promote wildfires, crop losses, food price spikes and conflicts. Antonio Gasparrini Senior Lecturer, London School of Hygiene and Tropical Medicine: My review is limited to the part of the article that describes the results of the study published in The Lancet, which I first-authored. The interpretation provided in the article is misleading, as our study is meant to provide evidence on past/current relationships between temperature and health, and not to assess changes in the future. In addition, the study does not offer a global assessment, and it is limited to a set of countries not representative of the global population. Alexis Berg Research Associate, Harvard University: Bjorn Lomborg disputes the notion, presented in a recent national assessment report, that global warming will increase the number of temperature-related deaths in the US. To do so, he carefully picks studies and uses flawed reasoning. Instances of faulty reasoning include Lomborg’s interpretations of the facts that i) cold-related deaths currently outnumber heat-related ones and ii) migration patterns in the last decades indicate that people are generally moving to the warmer, Southern part of the US. However, i) does not imply that warmer temperatures will reduce deaths: what matters is the sensitivity of the death-risk to a change in temperature, and that appears to be higher for heat than for cold; as for ii), migration patterns are not driven only by climate, and probably account for future climate change even less so. While Mr. Lomborg’s single focus on deaths directly related to temperature could imply that it is the only thing that matters, it clouds out (whether on purpose or not) all the other impacts expected from global warming: impacts on ecosystems, agriculture, water resources, sea level rise, etc. Those other impacts are also expected to have detrimental effects, if not directly on the lives or deaths of Americans, at least on their welfare and on America’s prosperity. Stephan Lewandowsky Professor, University of Bristol: Mr Lomborg points to a skewed and highly selective sample of the literature and ignores many other well-established findings that would undermine his argument. For example, the article ignores the recent finding that economic productivity declines with increasing temperatures past a fairly cool inflection point, and that this relationship remains unchanged even after considerable time for adaptation has elapsed. The article also ignores the adverse effects of climate change on agricultural production; the demonstrable relationship between heat and migration; the association between heat and interpersonal violence at all scales; the fact that unmitigated climate change will eventually make parts of the planet uninhabitable due to the increase of temperatures beyond the life-threatening threshold of 35C (wet bulb temperature, not dry temperature). Bizarrely, for an article concerned with the health effects of climate change, Mr Lomborg also fails to mention the demonstrable health benefits that are associated with cutting carbon emissions due to a reduction in pollution-related mortality. Unfortunately, therefore, the article fails to inform but instead misleads the readership by an extremely selective reporting of the literature. Steven Sherwood Professor, University of New South Wales: The article raises legitimate issues but its key point that cold kills more people than heat is misleading, because heat deaths will skyrocket once global temperature has risen significantly while the benefits on the cold side will decline. Indeed there is a strict limit to human tolerance of heat and humidity, that may be approached in some regions within a century and would cause severe stresses. Philip Staddon Lecturer/Visiting Scholar, The Open University, Xi’an Jiaotong-Liverpool University: Lomborg is using scientific ‘language’ to suggest that climate change will have insignificant health impacts; this goes against a vast body of evidence. The notion that benefits from warmer winters could be more important than risks from hotter summers in terms of human health is plain wrong. For once, the US administration is taking health impacts of climate change seriously, and it is particularly unhelpful to attempt to confuse the public on this issue. David Mills Managing Analyst, Stratus Consulting: The article claims the new U.S. Global Change report overlooks the evidence about the relative significance of mortality attributed to cold (and the cold season) relative to heat (and the hot season) while in reality, it is included (see Sections 2.5 and 2.6). Similarly, Lomborg uses selective representation of published literature and puts the emphasis on studies outside the U.S., while the new report specifically notes it focuses on reviewing U.S. based studies. Katrin Meissner Professor, University of New South Wales: This article is cherry-picking and presents scientific results in a misleading way. Rasmus Benestad Senior scientist, The Norwegian Meteorological institute: I think the article misrepresents statistics and cherry picks some facts to support its position while ignoring relevant ones. There may be some validity in some of the points. Overall, the message is very dubious. For the interested reader, here is an insightful discussion on the topic of how climate change threatens U.S. population’s health. Michael Brauer Professor, The University of British Columbia: The article is selective in its interpretation of the temperature-mortality relationship. It is correct that both cold and warm temperatures kill and that, at present, cold kills more than heat but that does not imply that future warming will lead to fewer cold-related deaths than any increase in heat-related deaths, these relationships are complex and non-linear. It also discusses one part only of a comprehensive assessment to argue that the whole assessment is incorrect/invalid. This is biased. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time.Key Take-aways : The statements quoted below are from Bjorn Lomborg; comments and replies are from the reviewers. 1. Climate change impacts on health are not limited to just cold and heat-related deaths but also include air quality, extreme events, diseases carried by parasites… “Higher temperatures, we’re told, will be deadly—killing “thousands to tens of thousands” of Americans” Alexis Berg Research Associate, Harvard University: Whether this is on purpose or not, Mr. Lomborg’s immediate focus on the part of the report dealing with temperature-related deaths makes it sound as if this is the only focus of the report. However, the report also deals with air quality impacts, food safety, extreme events, etc. “cold kills many more people than heat.” Kristie Ebi Professor, University of Washington: Mr. Lomborg is confusing seasonal mortality with temperature-related mortality. It is true that mortality is higher during winter than summer. However, it does not follow that winter mortality is temperature-dependent (which summer mortality is). Dave Mills and I reviewed the evidence and concluded that only a small proportion of winter mortality is likely associated with temperature. A growing numbers of publications are exploring associations between weather and winter mortality, with differences in methods and results. The country with the strongest association between winter mortality and temperature is England, which appears in other publications to be at least partly due to cold housing. Winter mortality is lower in northern European countries. Rasmus Benestad Senior scientist, The Norwegian Meteorological institute: This is cherry picking – even if it were true. Climate change is much more than just temperature. It also affects precipitation and the lack thereof – with consequences such as floods, mud slides, droughts, and wildfires. Furthermore, the cold is fairly limited to the high northern latitudes, … and not so many live there, but many more in the warm tropics… These rich countries also have the means to collect statistics. The poor developing countries often lack credible statistics, and I do not believe for a second that we have an estimate of all people who die from heat stress in Asia, Africa, and Latin America. Philip Staddon Lecturer/Visiting Scholar, The Open University, Xi’an Jiaotong-Liverpool University: Lomborg seems unaware of, or more likely is ignoring, the fact that climate change caused by human activities is making the climate not only warmer but more unpredictable: increased intensity and frequency of extreme weather events including drought, heavy downpours, heat waves… “In pushing too hard for the case that global warming is universally bad for everything, the administration’s report undermines the reasonable case for climate action.” Alexis Berg Research Associate, Harvard University: As seems to always be the case with Lomborg (cf his previous WSJ’s article reviewed by Climate Feedback), he picks up a few studies that support his position. Note, first, that the report’s claim about projected heat-related deaths outweighing cold ones applies to the US: different regions might have different responses… Second, when reviewing the literature on the topic, the IPCC report indicates (WGIIAR5-Chap11, p.721): “it is not clear whether winter mortality will decrease in a warmer, but more variable, climate (Kinney et al., 2012; Ebi and Mills, 2013). Overall, we conclude that the increase in heat-related mortality by mid-century will outweigh gains due to fewer cold periods, especially in tropical developing countries with limited adaptive capacities and large exposed populations” So the US report does not appear wildly at odds with the literature on the topic, or to be “pushing too hard”. Also, it does not say that warming is universally bad, just that the bad outweighs the good on this particular topic. 2. It is not obvious that winter-death will decrease due to climate change, contrary to Lomborg’s claim “…climate change will also reduce the number of cold days and cold spells. That will cut the total number of cold-related deaths.” Philip Staddon Lecturer/Visiting Scholar, The Open University, Xi’an Jiaotong-Liverpool University: The assertion that warmer winters = less mortality is a schoolboy error. Indeed everyone knows that European countries with warmer climates and milder winters actually have MORE not LESS winter mortality; principally due to adaptation. The current numbers of winter mortality may well be higher than summer heat wave mortality in many temperate to northern countries, however what is crucially important is that evidence points to significant increase in summer heat related mortality and no or very little change to winter mortality as a result of climate change. Katrin Meissner Professor, University of New South Wales: A recent paper by Kinney et al. (Winter season mortality: will climate warming bring benefits?) suggests that reductions in cold-related mortality under warming climate may be much smaller than some have assumed. Kinney and colleagues analyzed excess winter mortality across multiple cities and over multiple years within individual cities. They found that excess winter mortality was no lower in warmer vs. colder cities, suggesting that temperature is not a key driver of winter excess mortality. In addition, variability in daily mortality within cities was not strongly influenced by winter temperature. Kristie Ebi Professor, University of Washington: There is very limited scientific support for the claim that reducing the number of cold days (by which he apparently means winter) will reduce the number of cold-related deaths. Again, this is assuming winter mortality is temperature-dependent; an assumption not verified by research in the US and elsewhere. “The administration’s new report refers to this study … but only in trivial ways, such as to establish the relationship between temperature and mortality.” Antonio Gasparrini Senior Lecturer, London School of Hygiene and Tropical Medicine: As previously noted, [our] study contributes evidence only to ‘direct’ effects of temperature on human health. As a matter of fact, this is likely to represent a minor part of the total excess mortality and morbidity due to a changing climate. 3. Lomborg misrepresents the U.S. Global Change report that he criticizes and he misunderstands the Lancet study that he uses to support his case “Not once does this “scientific assessment” acknowledge that cold deaths significantly outweigh heat deaths.” Alexis Berg Research Associate, Harvard University: That’s not true. Under section 2.5, the report indicates: “A recent analysis of U.S. deaths from temperature extremes based on death records found an average of approximately 1,300 deaths per year from 2006 to 2010 coded as resulting from extreme cold exposures, and 670 deaths per year coded as resulting from exposure to extreme heat. These results, and those from all similar studies that rely solely on coding within medical records to determine cause of deaths, will underestimate the actual number of deaths due to extreme temperatures.” And then further down (my emphasis): “studies based on statistical approaches have found that, despite a larger number of deaths being coded as related to extreme cold rather than extreme heat, and a larger mortality rate in winter overall, the relationship between mortality and an additional day of extreme heat is generally much larger than the relationship between mortality and an additional day of extreme cold.” “Consider a rigorous study published last year in the journal Lancet that examined temperature-related mortality around the globe.” Antonio Gasparrini Senior Lecturer, London School of Hygiene and Tropical Medicine: As the first author of this article, I deem it is worth pointing out that the aim of this study is to establish the association between non-optimal temperature and mortality (in terms of excess deaths) in the recent past, using historical data. The article clearly acknowledges that these results cannot be easily extrapolated to the future, in particular under climate change scenarios, for a series of reasons detailed in the discussion section of the article. For instance, the change in heat and cold-related deaths will depend on changes in future temperature distribution, which is likely to be more complex than a simple upward shift. “The report confidently claims that when temperatures rise, “the reduction in premature deaths from cold are expected to be smaller than the increase in deaths from heat in the United States.” Six footnotes are attached to that statement.” Alexis Berg Research Associate, Harvard University: The report says “The decrease in deaths and illness due to reductions in winter cold have not been as well studied as the health impacts of increased heat, but the reduction in premature deaths from cold are expected to be smaller than the increase in deaths from heat in the United States“. This doesn’t sound over-confident to me; and as for the “footnotes”, there are scientific references to back up that claim, not asterisks leading to fine-print caveats… 4. Excess mortality during cold days does not imply people died from the cold (think influenza…) “In the U.S. about 9,000 people die from heat each year but 144,000 die from cold.” Alexis Berg Research Associate, Harvard University: These numbers are not deaths reported as clinically due to heat or cold. It seems Lomborg computed them from the Lancet study, using percentages given by the study, times the total number of deaths. Kristie Ebi Professor, University of Washington: Where do these numbers come from? According to a review of national health statistics: During 2006–2010, about 2,000 U.S. residents died each year from weather-related causes. About 31% of these deaths were attributed to exposure to excessive natural heat, heat stroke, sun stroke, or all; 63% were attributed to exposure to excessive natural cold, hypothermia, or both; and the remaining 6% were attributed to floods, storms, or lightning. This statement also confuses seasonal mortality with mortality from extreme events. As noted in Ebi and Mills, this distinction is important for understanding what could happen with climate change. Philip Staddon Lecturer/Visiting Scholar, The Open University, Xi’an Jiaotong-Liverpool University: In the UK for example, the evidence now shows NO strong link between how cold a winter is and how many deaths occur. Sure the link was very strong up until the 1970s, but Lomborg might be aware that since the 1950s there have been massive improvements in building, heating, aid to the poorest, healthcare. How winter temperatures affected mortality in the 50s is no longer relevant. The key driver for annual variation in winter mortality in rich countries now appears to be incidence and virulence of influenza and similar diseases. Antonio Gasparrini Senior Lecturer, London School of Hygiene and Tropical Medicine: As previously noted, the study published in The Lancet contributes little to understanding how these figures will change in the future under scenarios of climate change. In particular, it is difficult to ascertain from these results if the supposed decrease in cold-related deaths will offset the supposed increase in heat-related mortality. “cold deaths actually occur during moderate temperatures” Rasmus Benestad Senior scientist, The Norwegian Meteorological institute: This suggests that the dependency is not linear, and there is a multitude of factors involved. Hence, “cold deaths” may be a misnomer. The temperature is a moderator combined with standard of living, life-style diseases, pollution, and poverty, in addition to accidents and other weather conditions… “The Lancet researchers found that about 0.5%—half a percent—of all deaths are associated with heat, not only from acute problems like heat stroke, but also increased mortality from cardiac events and dehydration. But more than 7% of deaths are related to cold—counting hypothermia, as well as increased blood pressure and risk of heart attack that results when the body restricts blood flow in response to frigid temperatures.” Alexis Berg Research Associate, Harvard University: I do not want to question the quality of this particular study, but it’s worth looking at how they get such numbers. First, this is a statistical study where they look at data on numbers of deaths and temperatures in various locations: of course, nothing says if, or how, these deaths are really related to temperature (heat or cold). This is an empirical study. Lomborg’s comments suggest that the authors of this study are counting deaths explicitly caused by heat or cold, but this is not the case. Second, they basically fit a temperature-death risk response curve to this data. They then see for what temperature the mortality risk is lowest – and then they aggregate all the deaths below (for cold-related deaths) and above (for heat-related ones) that temperature. Because the temperature of minimum mortality is often high (around 20-25C, or lower 70’s F), for cold-related deaths this leads to integrating the response function (even with low death risks) over much of the temperature distribution. See plots below. The authors indicate as much: “This difference was mainly caused by the high minimum-mortality percentile, with most of the mean daily temperatures being lower than the optimum value.” This methodology also explains why most cold-related deaths appear due to “moderate cold”. This is worth explaining, because I am not sure dying in 15C weather (60F) in Rome or Sydney is really what people will understand when they read about “cold-related deaths”! From Gasparrini et al. figure 1: Exposure–response associations as best linear unbiased prediction (with 95% empirical CI, shaded grey) in representative cities of the 13 countries, with related temperature distributions. Solid grey lines are minimum mortality temperatures and dashed grey lines are the 2.5th and 97.5th percentiles. RR=relative risk. The other thing that is easy to see is that the risk curve generally increases slowly towards cold temperature, but a lot more steeply past high temperatures. So even if one agrees with how this study classifies and counts “cold deaths”, the fact that they outnumber heat deaths, in absolute numbers, does not necessarily mean that increasing temperatures will reduce deaths: based on these plots, it could well be that warming will reduce cold-related deaths less than it increases heat-related ones. And indeed, this is what the studies about future projection of temperature-related deaths that they cite, and that Lomborg discusses, do find. 5. Southern states will likely become less attractive due to impacts of climate change “Consider where they move. Migration patterns show people heading for warm states like Texas and Florida, not snowy Minnesota and Michigan.” James Renwick Professor, Victoria University of Wellington: This focuses on average climate rather than on extremes, and such patterns of migration are based on our knowledge of the past. As the frequency of extreme hot days increases, as the number of extreme hurricanes increases, and as sea levels rise, people may find that Florida is not so attractive after all. Alexis Berg Research Associate, Harvard University: People don’t like the cold, they like sunshine and warmth, and (supposedly as a result, according to Lomborg), they move to the South: does Lomborg really want us to deduce from that that global warming will thus be good for us – even simply in terms of temperature-related deaths? That’s not reasonable. First, while people have indeed generally been moving from the North(-East) to the South over the last decades, it’s not only because of “better climate”: quoting this article by the Washington Post, “Several long-term trends dating as far back as the 1960s are behind this larger pattern. The rise of air conditioning and interstate highways have made once-sleepy (and sweltering) Southern cities more appealing. And, over the same time, the decline of industrial jobs in the Midwest and Northeast have pushed people out. Cheap housing during the boom years also drove growth in states such as Arizona and Nevada“. I think that is already much more reasonable than saying that people move South only because they know they are less likely to die from cold exposure there. Second, people may be moving there right now partly because of climate, and that may indeed be a “smart” move because, TODAY, indeed, current cold-related deaths outnumber heat-related deaths. However, even supposing that this is a significant factor in their decision process, it’s not clear that they are also thinking about future warming. So the fact that people are moving there NOW does not even logically imply, as Lomborg would have it, that FUTURE warming will be beneficial – which is the point of interest here. Kristie Ebi Professor, University of Washington: This has more to do with economic factors than weather. If people moved only because of poor weather, why hasn’t everyone left Northern Europe?

https://science.feedback.org/review/washington-post-chris-mooneys-earth-no-parallel-66-million-years/

1.5

The Washington Post, by Chris Mooney, on 2016-03-21.

"What we’re doing to the Earth has no parallel in 66 million years, scientists say"

Chris Mooney reports on a new scientific study that shows the current rate of increase of carbon dioxide in the atmosphere is unprecedented in the record of the last 66 million years. The seven scientists who reviewed the article confirmed that it is accurate and insightful. While a significant die-off of oceanic species coincided with the rapid increase in CO2 that happened around 55 million years ago, the rate of carbon release from human activities today is at least ten times as fast, suggesting the negative consequences on marine life could be greater this time.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. The Washington Post article refers to an article published in Nature Geoscience. In the original scientific article, the authors use an elegant model-data comparison twist to evaluate whether the carbon release was rapid enough to produce a detectable lag in the climate response to the initial carbon release. Although the publication is rather technical, the Washington Post article effectively highlighted the primary message: according to the authors’ best estimate of the carbon release rate, humans might well release carbon ten times more rapidly than what likely happened during the PETM (Palaeocene–Eocene Thermal Maximum). It sadly implies that even the PETM, a massive warm climatic excursion, might not be harsh enough to represent an analogue for future climate change, as the Washington Post rightfully points out. The article does a very good job in working out the main message of the original scientific paper in an understandable way without oversimplification. The statements are generally correct, except maybe at one point, where it is said that “the researchers used a deep ocean core of sediment”. The sediment core is actually not from the deep ocean but from a rather shallow continental margin site with a high accumulation rate, if I get it right. But this is a minor detail, the main story is conveyed very nicely in this article. Ken Caldeira Senior Scientist, Carnegie Institution for Science: Overall, the article seems to me to be a sound representation of the underlying work. Further, the underlying work appears to be sound. Overall, a well done piece. We need a lot more science reporting of this quality. Katrin Meissner Professor, University of New South Wales: This is a well written and accurate article. Michael Henehan Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: I see no problems with this article. It’s a pretty fair representation of one of the key findings of a new paper. Chris Mooney does a great job of placing the results of this study into a modern context. His statements are well supported by existing peer-reviewed literature. Alexis Berg Research Associate, Harvard University: As far as I can tell, this article accurately reports on a recent paleoclimate study investigating the PETM event and the rate of carbon release during that event. The article conveys the study’s conclusion accurately, i.e., that current, man-made rates of carbon release into the atmosphere are unprecedented. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : 1. Past changes in Earth’s climate have been associated with mass extinctions “about 56 million years ago … The planet proceeded to warm rapidly, at least in geologic terms, and major die-offs of some marine organisms followed due to strong acidification of the oceans.”Ken Caldeira Senior Scientist, Carnegie Institution for Science: The event was a “strong acidification” event relative to changes that ordinarily occur over geologic time but it was a weak event compared to what our modern industrial society is threatening to produce. If anything, Chris Mooney is erring on the side of downplaying risks from ocean acidification by saying that “major die-offs” were associated with a “strong acidification” event, when in fact they have been associated with events that are far weaker than we will produce with continued burning of coal, oil, and gas. Katrin Meissner Professor, University of New South Wales: There are several potential causes for the benthic extinctions that are seen in sediment cores. In addition to acidification, abrupt warming of bottom waters, decrease in dissolved oxygen and a potential decrease in food availability (raining down from surface layers) have been put forward in the past (e.g. Thomas [2003] Extinction and food at the seafloor…; Thomas [2007] Cenozoic mass extinctions in the deep sea…; Sluijs et al. [2007] The Palaeocene–Eocene Thermal Maximum super greenhouse…; McInerney and Wing [2011] The Paleocene-Eocene Thermal Maximum: A Perturbation of Carbon Cycle, Climate, and Biosphere with Implications for the Future). 2. Humans are now releasing carbon dioxide at about 10 times faster than the most rapid event of anytime in at least the past 66 million years “We’re putting carbon into the atmosphere at an even faster rate than happened back then.”Lee Kump Professor, PennState University: We are now exceeding by an order of magnitude the rate of carbon release during one of the most remarkable global warming events in Earth’s history. “In contrast, humans are now emitting about 10 billion tons annually — changing the planet much more rapidly.” Alexis Berg Research Associate, Harvard University: This is the current rate, but it’s worth pointing out that this rate is the result of exponential growth over the last decades, and that it was “only” 1-2 billion tons in the 50’s, for instance. In drawing the analogy with the PETM, one may also wonder how long the current rates can be sustained – if anything, compared to the 4,000 years of the PETM – given that such emissions are most likely unsustainable over the long-term, either because of fossil fuel availability constraints, or because of the adverse feedback of climate change on human societies.

https://science.feedback.org/review/scientists-are-exaggerating-carbon-threat-to-reefs-and-marine-life/

-2

The Australian, The Times, by Ben Webster, on 2016-03-01.

"Scientists are exaggerating carbon threat to marine life"

Ben Webster reports that the threat posed by ocean acidification to marine life is “exaggerated”. The article, written for The Times and republished in The Australian, is based on an interview by Dr Howard Browman, editor of a special issue on ocean acidification, who claims that Webster quotes him in a misleading way. The article is not representative of the state of scientific knowledge.See all the scientists’ annotations in contextGUEST COMMENTS: Howard Browman Principal Research Scientist, Norwegian Institute of Marine Research: The Times article is not representative of the message that I tried to give the journalist during the interview – that is, the message presented my introduction to the special issue in which I state clearly and explicitly that ocean acidification IS happening and WILL have effects. After reading my introduction, and the articles in the special issue, readers can come to their their own conclusion about whether the journalist worked carefully, conscientiously and impartially to help me accurately spread its messages. I spoke with Ben Webster of The Times in a 30-minute phone call and explained that the objective of the special issue he was reporting on was to introduce more balance into the topic of Ocean Acidification. He cherry-picked our conversation and presented phrases out of context – seemingly in order to be sensational – despite the fact that I told him that the press was part of the “exaggeration” problem. For example, the quoted phrase “inherent bias” in the first paragraph is not the same as the “publication bias” that I refer to in my introduction. Further, my introduction does not say that the existing literature is “exaggerating” the effects of ocean acidification, but that more careful interpretation is required. Finally, I am not saying that the special issue overturns previous literature on the topic, as the Times suggests, but that they should be taken together, in balance. Very disappointing.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Ken Caldeira Senior Scientist, Carnegie Institution for Science: The main problem with this article is that it quotes a single source (Dr. Browman) who has views that differ from much of the scientific community. The author of this article did not interview anyone that Dr Browman is criticizing. Note: “my comments were made before I learned that Dr Howard Browman felt his views were misrepresented in the article”. (added on Mar. 4 2016) Jean-Pierre Gattuso Research Professor, CNRS, Université Pierre et Marie Curie and IDDRI: This article brings together a series of inaccurate and misleading statements on the science of ocean acidification. Adam Subhas PhD candidate, Caltech: This article misses some major intellectual points about ocean acidification, thanks to what seems to be a willful misunderstanding and misquoting of an interview with Dr. Browman on an Ocean Acidification special issue journal. Mark Eakin Scientist, Coordinator of NOAA’s Coral Reef Watch, National Oceanic and Atmospheric Administration: The reporter uses inflammatory language and cherry-picks parts of the paper to create a story that is basically untrue. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time.Key Take-aways : 1. Research shows that Ocean Acidification has serious consequences for marine life “More than half of the 44 studies selected for publication found that raised levels of CO2 had little or no impact on marine life, including crabs, limpets, sea urchins and sponges”Jean-Pierre Gattuso Research Professor, CNRS, Université Pierre et Marie Curie and IDDRI: This is meaningless… it is not unexpected that several papers published in the issue showed little or no impact because the call for papers specifically welcomed such contributions. The bias is therefore very high. I recommend using the unbiased dataset investigated by Kroeker et al. (2013). It does demonstrate negative impacts on some processes and groups of organisms. Kroeker K. et al., 2013. Impacts of ocean acidification on marine organisms: quantifying sensitivities and interaction with warming. Global Change Biology 19:1884-1896. Adam Subhas PhD candidate, Caltech: It is crucial to understand exactly which species are and aren’t affected by Ocean Acidification, as that will determine how ecosystems will change through time. I will also point out that if this figure is correct, and 50% of organisms are unaffected by Ocean Acidification, 50% of organisms are affected by Ocean Acidification, which is a HUGE amount of marine life. It also neglects the fact that reefs themselves are most definitely affected, which creates and maintains the habitat for many of these other organisms in the first place. “The term ocean acidification was also a misnomer, he said, because it suggested that the oceans could become acidic instead of alkaline.”Ken Caldeira Senior Scientist, Carnegie Institution for Science: This is like saying that it is wrong to say the Arctic is warming because it is still cold. ‘Warming’ and ‘acidifying’ both refer to a direction of change and do not specify the state of the system. This claim about a misnomer is based on a misunderstanding of how words are used. “The oceans will never become acid because there is such a huge buffering capacity in the oceans. We simply could never release enough CO2 into the atmosphere to cause the pH to go below 7 [the point in the pH scale at which a solution becomes acidic].”Adam Subhas PhD candidate, Caltech: This statement sets up a false notion about the pH balance of the oceans. In fact, the global ocean is, on weighted average, very close to (but just above) 7, which is controlled by many factors including atmospheric CO2 changes, but most importantly by the buffering from carbonate-rich sediments. This buffering timescale is slow, such that there can in fact be a decoupling of ocean pH from the main buffering capacity of seawater (see Honisch et al, Science, 2012 The Geological Record of Ocean Acidification). This statement also fails to acknowledge the thermodynamic threshold to skeleton-building (saturation state), which for corals and many other organisms falls well above pH 7. “If they had called it something else, such as ‘lower alkalinity’, it wouldn’t have been as catchy”Adam Subhas PhD candidate, Caltech: CO2 has zero effect on alkalinity. “They” would have never called Ocean Acidification ‘lower alkalinity’, because that is simply an incorrect thing to say. 2. The article misrepresents the nature of scientific inquiry “The review found that many studies had used flawed methods, subjecting marine creatures to sudden increases in carbon dioxide that would never be experienced in real life. In some cases it was levels far beyond what would ever be reached even if we burnt every molecule of carbon on the planet”Ken Caldeira Senior Scientist, Carnegie Institution for Science: It is normal in scientific investigation to study impacts of large doses as a step towards understanding impacts of smaller doses. Just because a study considered high doses, that in no way undermines the value of a study. Jean-Pierre Gattuso Research Professor, CNRS, Université Pierre et Marie Curie and IDDRI: This is an incorrect statement which has already been debunked before, including by two of the authors of the paper this manuscript referee to. Hurd C. L., Cornwall C. E., Dupont S., Gattuso J.-P., Hoegh-Guldberg O., Gao K. & Lagos N. A., 2015. Ocean acidification: Laboratory seawater studies are justified. Nature 525:187. Extreme values are useful for physiologists to elucidate the cellular and molecular pathways confering susceptibility or resistance to elevated CO2. Yang et al. (2016; fig. 8d) showed that most of the data on the biological response to ocean acidification archived in a World Data Centre were collected at pCO2 values below 1000 uatm, in agreement with the business-as-usual CO2 emission scenario. Yang Y.et al., 2016. Data compilation on the biological response to ocean acidification: an update. Earth System Science Data 8:79-87. “An “inherent bias” in scientific journals in favour of more calamitous predictions has excluded research showing that marine creatures are not damaged by ocean acidification, which is caused by the sea absorbing carbon dioxide from the atmosphere.”Jean-Pierre Gattuso Research Professor, CNRS, Université Pierre et Marie Curie and IDDRI: A publication bias towards positive results is inherent to all fields of research. But I believe that it is far from being as bad as the article suggests. The most recent and comprehensive meta-analysis of the impact of ocean acidification shows that many processes and taxonomic groups exhibit no statistically significant response (Kroeker et al., 2013). This demonstrates that many non-calamitous papers are published. Kroeker K. et al., 2013. Impacts of ocean acidification on marine organisms: quantifying sensitivities and interaction with warming. Global Change Biology 19:1884-1896. Ken Caldeira Senior Scientist, Carnegie Institution for Science: In all fields of research, it is much easier to publish a paper saying ‘We were able to develop convincing evidence that X affects Y’ than to publish a paper saying that ‘We were not able to develop convincing evidence that X affects Y’. That is a bias that is inherent in all of modern science and is not specific to ocean acidification research. Mark Eakin Scientist, Coordinator of NOAA’s Coral Reef Watch, National Oceanic and Atmospheric Administration: This is an inflammatory twisting of the author’s words. Browman discusses the well-known bias against publication of negative results. It has nothing to do with the direction of the signal, only the inability of the researchers to demonstrate an effect in their experiments. It has nothing to do with how “calamitous” the predictions are. In fact, sometimes the negative results would have been more calamitous depending on the experimental design. “Dr Browman, a marine scientist for 35 years, said he was not saying that ocean acidification posed no threat, but that he believed that “a higher level of academic scepticism” should be applied to the topic.Ken Caldeira Senior Scientist, Carnegie Institution for Science: By making such broad statements, Dr Browman is undermining the hard work of many people who have spent a huge amount of effort to document the effects of ocean acidification on many marine species. If Dr Browman wants to attack particular studies, he should cite particular statements from particular papers that he thinks are false. It is inappropriate to make vague accusations denigrating an entire field of inquiry. Adam Subhas PhD candidate, Caltech: There is a degree to which scientific skepticism should be applied to Ocean Acidification experiments. There are many “cook and look” type experiments that investigate short term, single-species effects which are often not representative of the real world, include no mechanistic or physiological explanation, and lack any sort of adaptive response from the organism itself. However, the field as a whole is moving away from this approach, thanks to the hard work of many ecologists, biologists, chemists, and oceanographers working together, generating data, and participating in the scientific method. Examples of this progress can be found in the articles Gattuso, Caldeira, and I, have cited above.

https://science.feedback.org/review/sea-level-rise-global-warming-climate-change/

1.7

The New York Times, by Justin Gillis, on 2016-02-22.

"Seas Are Rising at Fastest Rate in Last 28 Centuries"

Justin Gillis reports on new results showing that the current rate of sea level rise is unprecedented in a record dating back 2,000 years. The article explains that this rise is attributable to human-induced climate change, and that higher sea levels are already impacting coastal communities. The seven scientists who reviewed the article confirmed that it is accurate and insightful. Note that results about the increased frequency of coastal flooding in the US discussed in this article are from a Climate Central’s analysis that has not undergone formal peer-review. We wish to stress this point as peer-review is a mechanism that allows to increase the trust one can have in a result and ensures the work meets higher standards of scientific quality.See all the scientists’ annotations in context GUEST COMMENTS: Robert Nicholls Professor of Coastal Engineering, University of Southampton:The article by Kopp et al (on which The New York Times is reporting) provides a quite convincing attribution of much of 20th century and early 21st century sea-level rise to human-induced warming. It shows that the recent rate of rise in sea level is unprecedented in more than 2000 years of record and that these changes are almost certain to accelerate substantially into the future. Interestingly this new analysis also appears to reinforce the conclusions of the IPCC Fifth Assessment Report about sea-level rise expectations through the 21st century. While human activity has been linked to sea level rise forecasts before, here human activity is linked to observed changes, which is an important improvement. REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Andrea Dutton Visiting Associate Professor, University of Wisconsin:This article is an accurate and insightful summary of the recently published research on this topic. Justin Gillis has a strong background in this topic which comes across through his careful language and nuanced understanding of the issues. Note however that the Climate Central report is not peer-reviewed literature. This was not clear in much of the press coverage and was not clear at the beginning of this article where these two “studies” are presented as equals. Even if the report by Climate Central is correct, it should not be elevated to the status of peer-reviewed literature by the media. James E Neumann Principal, Industrial Economics:The article is highly accurate and cites relevant new work, but omits other recent relevant work (Andrea Dutton has provided in annotations) and what might be helpful discussions of the key mechanisms of sea level rise. These are relatively minor points. Aimée Slangen Researcher, Royal Netherlands Institute for Sea Research (NIOZ):The article gives a good overview and insight into the main conclusions of both the Climate Central report (by Dr. Strauss) and the research paper (by Dr. Kopp), and links the two well. Rasmus Benestad Senior scientist, The Norwegian Meteorological institute:The article gives a good account of some new papers that recently have been published about the global sea level. Stephan Lewandowsky Professor, University of Bristol:The article does a very good job reporting the papers and is entirely accurate. I did not spot any errors or even minor glitches–well done. Mr Gillis does an exemplary job in reporting science factually and accurately. Notes: [1]See the rating guidelines used for article evaluations. [2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : The quotes below are from Justin Gillis’ article. 1. Current pace of sea level rise is unprecedented in history of human civilization and this rate of sea level increase cannot be explained without human influence. “in the absence of human emissions, the ocean surface would be rising less rapidly and might even be falling.” Aimée Slangen Researcher, Royal Netherlands Institute for Sea Research (NIOZ):To clarify: the study by Kopp et al uses hypothetical temperature scenarios to show that if temperatures in the 20th century had been similar to the average temperature of the years 500-1800, sea-level rise would have been less rapid or even falling. “Based on extensive geological evidence, scientists already knew that the sea level rose drastically at the end of the last ice age… They also knew that the sea level had basically stabilized, like the rest of the climate, over the past several thousand years”Emmanuel M Vincent Research Scientist, University of California, Merced:This statement is supported by a recent report in Nature Climate Change written by 22 scientists. The figure below shows that global sea level rose by about 100 meters at the end of the last ice age 15 thousand years ago and that sea level had stabilized more than 5 thousand years ago. This helps clear a common misconception that current rate of sea level rise could be simply due to the end of the ice age. Long-term global mean sea-level change for the past 20,000 years (black line) based on palaeo sea level records and projections for the next 10,000 years for four emission scenarios. From Fig. 2 in Past and future changes in global mean sea level 2. Sea level rise has and will have very significant economic impacts, for instance by flooding coastal cities. “The worsening of tidal flooding in American coastal communities is largely a consequence of greenhouse gases from human activity, and the problem will grow far worse in coming decades, scientists reported Monday.” Andrea Dutton Visiting Associate Professor, University of Wisconsin:An accurate summary of the research that was published by Kopp et al. in PNAS. In fact, if anything, it is somewhat of an understatement given that the worsening of tidal flooding may be ENTIRELY due to the influence of greenhouse gases from human activity. This is based on the statement in the published research by Kopp et al (PNAS) that sea level in the 20th century may have “very likely risen by between -3 cm and +7 cm “, which is a way of saying that it may have fallen by 3 cm or risen by up to 7 cm over that time frame in the absence of [human-induced] global warming. Robert Nicholls Professor of Coastal Engineering, University of Southampton:While the rises in sea levels to date are small, they have had impacts and greatly increased nuisance flooding along the US East Coast as Strauss et al demonstrate. As sea levels continue to rise this will be extremely challenging to residents of the US East Coast and globally around the world’s coasts. This shows the benefits of sustained reductions in greenhouse emissions. Further these coastal communities will need to adapt in a systematic way to the sea-level rise that has occurred which is also challenging. “roughly three-quarters of the tidal flood days now occurring in towns along the East Coast would not be happening in the absence of the rise in the sea level caused by human emissions.” Emmanuel M Vincent Research Scientist, University of California, Merced:The trend in the number of “coastal flood days” in the US is convincing supporting evidence of this conclusion. Visualization created by Climate Central “Experts say the situation would then grow far worse in the 22nd century and beyond, likely requiring the abandonment of many coastal cities.” Andrea Dutton Visiting Associate Professor, University of Wisconsin:This statement is accurate. See Clark et al. (2016) Nature Climate Change (Consequences of twenty-first-century policy for multi-millennial climate and sea-level change, currently available online) or Dutton et al. (2015) Science, Sea-level rise due to polar ice-sheet mass loss during past warm periods. 3. Sea levels are expected to rise 0.5 to 1 meter on average by 2100, and the rise should impact mean sea levels for millenias. “One of the authors of the new paper, Dr. Rahmstorf, had previously published estimates suggesting the sea could rise as much as five or six feet by 2100.” Andrea Dutton Visiting Associate Professor, University of Wisconsin:This is an accurate representation of the previous and current research. It might have been nice to also note here that because the models he used probably don’t fully account for the rate of mass loss of ice from the polar ice sheets that the 3-4 feet estimate in the current research and in the IPCC may well underestimate the eventual magnitude of global mean sea-level rise by 2100. “In an interview, Dr. Rahmstorf said the rise would eventually reach five feet and far more — the only question was how long it would take. Scientists say the recent climate agreement negotiated in Paris is not remotely ambitious enough to forestall a significant melting of Greenland and Antarctica, though if fully implemented, it may slow the pace somewhat.” Andrea Dutton Visiting Associate Professor, University of Wisconsin:This is an accurate summary. To learn more about the eventual degree of melting in the future, see Clark et al (2016) Nature Climate Change (Consequences of twenty-first-century policy for multi-millennial climate and sea-level change, currently available online).

https://science.feedback.org/review/patrick-michaels-the-climate-snow-job-the-wall-street-journal/

-1.8

The Wall Street Journal, by Patrick Michaels, on 2016-01-24.

"The Climate Snow Job"

The article misleads readers with a series of sweeping claims about distinct aspects of climate science and the implications of global warming for the global economy. Most of the article is devoted to casting doubt over the accuracy of the global temperature record. The author uses detailed technical descriptions to distract readers from the inaccuracies of the article, which involve cherry-picking data to support multiple unsubstantiated and discredited claims.See all the scientists’ annotations in contextGUEST COMMENTS: Peter deMenocal Professor, Lamont-Doherty Earth Observatory, Columbia University, and Director, Center for Climate and Life: This is a simple, deliberate, and misleading conflation of (natural) El Niño variability and (anthropogenic) global warming trend to suggest that 2015 warmth is soley related to El Niño variability. It is very easy to debunk Michael’s suggestion that 2015 warmth is due only to El Niño, as shown by the other reviewers. The weather-related reinsurance risk statement itself is plain false (just read the MunichRe corporate statements), as is the statement that “Without El Niño, temperatures in 2015 would have been typical of the post-1998 regime“.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Ken Mankoff Senior Scientist, Geological Survey of Denmark & Greenland: The author attributes the record 2015 temperature only to El Niño. El Niño contributed, but was assisted into the record books by a general warming trend that is directly linked to human CO2 emissions. Every data set has issues and is incomplete or incorrect in some sense, and can be used to question a result, but a proper analysis of multiple independent data shows what is really happening. The author did not do this, and instead cherry-picks data and misleads the reader. Jennifer Francis Senior Scientist, Woods Hole Research Center: Patrick Michaels (note he is referred to as a ‘climatologist’ even though he does not have a PhD in climate science) contorts and misrepresents facts, deliberately misleads with disinformation, and demonstrates either his lack of knowledge or willful ignorance of the science. Britta Voss Postdoctoral Research fellow, U.S. Geological Survey: The author cherry-picks data to support multiple unsubstantiated and discredited claims. The detailed technical descriptions distract from the overall inaccurate picture presented by the article. Emmanuel M Vincent Research Scientist, University of California, Merced: The article argues about the effect of El Niño on global temperature but fails to include relevant information about the long term trend in global temperature observed by multiple lines of evidence. Rasmus Benestad Senior scientist, The Norwegian Meteorological institute: This letter is based on a series of misguided notions and does not rely on up-to-date knowledge. Victor Venema Scientist, University of Bonn, Germany: At least this Wall Street Journal piece penned by Patrick J. Michaels was not derogatory. James Renwick Professor, Victoria University of Wellington: This article is indeed a snow job, as the title implies. The author has twisted the facts and distorted the science wildly. The author is well known for his wildly inaccurate climate “forecasts”, see e.g. Patrick Michaels: Cato’s Climate Expert Has History Of Getting It WrongNotes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Featured Annotations: Below is a list of statements made by Patrick Michaels in his article along with comments and replies made by scientists. “Surface temperatures are indeed increasing slightly: They’ve been going up, in fits and starts” Victor Venema Scientist, University of Bonn, Germany: There are also other reasons why the global mean temperature changes from one year to the next, such as volcanoes and El Niño. You see these changes on top of the long-term trend due to increases in greenhouse gases. “in fits and starts” It is strange that Michaels emphasises this, because that is exactly the main reason why his idea that there was a “hiatus” in man-made global warming due to greenhouse gasses is so terribly wrong. Does anyone see a “hiatus” in the graph below? You no longer need statistics to tell you that this meme was wrong. “Before carbon dioxide from economic activity could have warmed us up, temperatures rose three-quarters of a degree Fahrenheit between 1910 and World War II.” Victor Venema Scientist, University of Bonn, Germany: Also before 1950 there was warming due to greenhouse gasses. Part of this warming was compensated by increases air pollution that also comes from burning fossil fuels. However, CO2 builds up, while air polution has a short life time. In the end, CO2 dominates. Before 1950 there was also warming due to natural causes due to less volcanoes and a stronger Sun. After 1950 we can say that our best estimate is that all warming was man-made, but also before 1950 part of the warming was man-made. All forcings (physical causes that change the temperature) are shown in this graph from the latest IPCC report. James Renwick Professor, Victoria University of Wellington: These changes are all a mix of solar radiation increase (before 1940), increased air pollution from industrialization mid-century, and greenhouse gas increase. Plus a few volcanoes and some natural variability. Models can capture all this really well, provided that they include the effects of greenhouse gas increase – otherwise, forget it. So sure, natural variations are in the mix, but human-induced greenhouse warming is becoming more important all the time. Shaun Lovejoy Professor, McGill University: This statement is a mixture of exaggeration and cherry picking. First for the cherry picking. Figure 1 shows that the period 1910-1944 had the largest 34 year warming since 1880. Figure 2 (see below) – the same data but plotted against the CO2 forcing, a surrogate for all anthropogenic effects – shows that by 1944 there was already about 0.3C (0.5F) of anthropogenic warming (i.e. 1944 was not “too early”). This is clarified in Fig. 3 that shows the residual: the estimate of the natural variability accounted for about 0.46C of the rise. This seems a lot for natural variablity – except that it was cherry picked to be the largest natural increase since 1880. Fig. 4 shows that it is almost exactly of the magnitude predicted by a 130-140 year return period. In other words this event is exactly as expected by the theory of anthropogenic warming! Such events are predicted by the theory. See : Lovejoy, S. 2014: Return periods of global climate fluctuations and the pause, Geophys. Res. Lett. 41, 4704-4710, doi: 10.1002/2014GL060478. Fig. 2: “Until last June, most scientists acknowledged that warming reached a peak in the late 1990s” Ken Mankoff Senior Scientist, Geological Survey of Denmark & Greenland: I’m not aware of any scientists that acknowledged this. This statement was always only true if you cherry-pick data and look at short time periods. 1998 was a record hot year, which is why many non-climate-scientists claimed “global warming stopped in 1998”, but that was incorrect. It was incorrect in 1999, and anytime between then and last June. See, for example, Climate myths: Global warming stopped in 1998 “a marginally significant warming trend in the data over the past several years, erasing the temperature plateau that vexed climate alarmists have found difficult to explain.” Britta Voss Postdoctoral Research fellow, U.S. Geological Survey: As this figure shows, the corrections made to the NOAA dataset last year only changed their global temperature estimates very slightly compared to their previous dataset. (See Karl et al., 2015, Science, for details). Regarding the “erasing” of the “temperature plateau” (aka “hiatus”), as NASA’s Gavin Schmidt pointed out, “The fact that such small changes to the analysis make the difference between a hiatus or not merely underlines how fragile a concept it was in the first place.” “When the Pacific circulation returns to its more customary mode, all that suppressed cold water will surge to the surface with a vengeance, and global temperatures will drop. Temperatures in 1999 were nearly three-tenths of a degree lower than in 1998, and a similar change should occur this time around, though it might not fit so neatly into a calendar year. Often the compensatory cooling, known as La Niña, is larger than the El Niño warming.” James Renwick Professor, Victoria University of Wellington: This avoids the point. If one fits a trend through just the El Niño years, or just the La Nina years, or just the neutral years, the result is the same – significant warming. ENSO adds year-to-year variations, but greenhouse gas increase provides the trend. source: National Climate Assessment 2014 “the rate of warming in the satellite-sensed data is barely a third of what it was supposed to have been” Victor Venema Scientist, University of Bonn, Germany: One wonders where this number, “a third”, comes from. The global mean temperature trend of the tropospheric temperatures (estimated by satellite) is very similar to that of the surface temperature over the short period for which we have satellite data. It is expected that the tropospheric temperature would rise a bit faster than the surface temperature, but this is a small deviation. Far from the completely false claim of Michaels that the warming is only a third of what it should be. As in any case, this deviation could be due to the models, the measurements, their data processing or the comparison. One would need to understand the reasons for this small deviation before one can claim that the models would need to be a little less sensitive. “50% the modeled temperature forecasts for the rest of this century” Rasmus Benestad Senior scientist, The Norwegian Meteorological institute: This is pure hand waving without any substance to support it. The comparison between climate models and measurements suggest a good agreement “The notion that world-wide weather is becoming more extreme is just that: a notion, or a testable hypothesis. As data from the world’s biggest reinsurer, Munich Re and University of Colorado environmental-studies professor Roger Pielke Jr. have shown, weather-related losses haven’t increased at all over the past quarter-century. In fact, the trend, while not statistically significant, is downward.” Laurens Bouwer Senior risk advisor, Deltares: This statement is not accurate, as 1) The main point is that up to now, we do not see an increase in loss records such as from Munich Re, due to anthropogenic climate change. That is not to say there is no increase in extreme weather, because there is. See IPCC SREX and AR5 reports, to which I also contributed. There is no signal in most loss records from floods and storms, though. So Patrick Michaels is misusing scientific information and consensus. And 2) it misses a point: there is an upward trend in losses, only after correction for population growth and wealth increase, this trend disappears. See the paper Roger Pielke and Munich Re wrote together, with me: Confronting Disaster Losses And also this recent review I did (freely accessible): Have Disaster Losses Increased Due to Anthropogenic Climate Change? James Renwick Professor, Victoria University of Wellington: Right… that’ll be why the Munich-Re website states (quoting Professor Peter Höppe, Head of Munich Re’s Geo Risks Research/Corporate Climate Centre): “Climate change is one of the greatest risks facing humankind this century. Through a part of its core business, the insurance industry is directly affected and therefore assumes a leading role in devising solutions for climate protection and adaptation to the inevitable changes.” “Last year showed the second-smallest weather-related loss of Global World Productivity, or GWP, in the entire record” Peter deMenocal Professor, Lamont-Doherty Earth Observatory, Columbia University, and Director, Center for Climate and Life: It is actually false, interesting that he brought this up. I consulted my reinsurance contacts and have several links that indicate the opposite view, that they are very concerned about mounting climate-related losses. Renaissance Re 2015 SEC document: “We believe, and believe the consensus view of current scientific studies substantiates, that changes in climate conditions, primarily global temperatures and expected sea levels are likely to increase the severity, and possibly the frequency, of weather related natural disasters and catastrophes relative to the historical experience over the past 100 years. Coupled with currently projected demographic trends in catastrophe-exposed regions, we currently estimate that this expected increase in severe weather, such as tropical cyclone intensity, over coming periods will increase the average economic value of expected losses, increase the number of people exposed per year to natural disasters and in general exacerbate disaster risk, including risks to infrastructure, global supply chains and agricultural production.” See also: “No climate-change deniers to be found in the reinsurance business“: “In Munich Re’s offices, there wasn’t much debate as the claims cheques flew out the door: The higher frequency of extreme weather events is influenced by climate change; and recent climate change is largely due to burning hydrocarbons. “I’m quite convinced that most climate change is caused by human activity,” says Peter Höppe, head of geo-risks research at Munich Re.“ Severe weather in North America, Munich RE

https://science.feedback.org/review/james-taylor-2015-was-not-even-close-to-hottest-year-on-record/

-1.8

Forbes, by James Taylor, on 2016-01-14.

"2015 Was Not Even Close To Hottest Year On Record"

This is an inaccurate and misleading report. It only comments on the temperature in the troposphere (not at the surface of the Earth, where people live) and ignores most of the data available to discuss whether or not Earth’s climate is warming. It is based on a single, unpublished and contested record. Note that another contributor to Forbes published an accurate article on the subject, however the inaccurate article has been read 15-20 times more (26k) than the accurate one (1.5k) as of Jan 22, 2016.See all the scientists’ annotations in contextGUEST COMMENTS: Carl Mears Senior Research Scientist, Remote Sensing Systems (RSS): The author is guilty of ignoring the surface temperature record, which is probably more accurate than the satellite temperature record. The author ignores the fact that record temperatures often occur in the year following an El Nino, because the global temperature response tends to lag the El Nino SST anomaly by 3-4 months. The author engages in excessive derogatory name calling, and appears to lump scientists in with “global warming activists”. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: This article makes startlingly inaccurate claims about the earth’s surface and satellite temperature records, as well as attempts to ascertain the earth’s temperatures over the past two millennia through proxy measurements. The author would do well to talk to scientists involved in surface and satellite records and to consult the peer-reviewered scientific literature rather than blogs when writing in the future.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Alexis Berg Research Associate, Harvard University: Very misleading and biased article. The author tries to confuse readers by using the satellite record of the lower atmosphere temperature to disprove the fact that 2015 was the warmest year, when everybody else is in fact referring to the mean temperature at the surface. They are slightly different things. Satellite measurements do not disprove surface measurements. A more interesting question would be to understand the difference between the two. A better-informed – and less biased – author would have addressed that and tried to explain it to their readers. Julien Emile-Geay Assistant Professor, University of Southern California: This is a highly misleading piece by an author with a history of cherry picking. Nothing in this piece is factually accurate. Furthermore, in relying on discredited reports by the Heartland Institute instead of the peer-reviewed literature, the author completely misinterprets the paleoclimate record, which only strengthens the point that 2015 is an exceptionally warm year, not just since 1979 but for the past 10,000 years. David Easterling Chief of the Scientific Services Division, NOAA's National Climatic Data Center: The coverage is a bit disingenuous since it only uses one satellite data set, and emphasizes the troposphere rather than the boundary layer [surface] where people actually live. The surface and upper air are two very different areas and their temperatures differ for lots of scientifically valid reasons. James Renwick Professor, Victoria University of Wellington: This piece is a rehash of several points that have been refuted many times over. The “satellite temperature record” from Roy Spencer is trumpeted so much because it is the only record that shows slow warming. Victor Venema Scientist, University of Bonn, Germany: The Forbes post of James Taylor provides the deepest possible contrast to the accurate New York Times article on the 2015 temperature record. Eric Guilyardi CNRS Research Director, Université Pierre et Marie Curie & Professor, University of Reading: A biased piece that confuses scientists and activists, full of inaccuracies and even plain errors. The author has obviously no expertise in climate science and did not seek to get some to write his piece. Quite poor journalism, if the term even applies. Britta Voss Postdoctoral Research fellow, U.S. Geological Survey: The author uses inaccurate and misleading claims (based on evidence from scientifically discredited sources) and rhetorical devices to confuse the facts and bias readers against legitimate climate science. Nothing in this article is either scientific or novel. Those are stale talking points that are constantly recycled by political operatives in pursuit of an agenda. The article contains major scientific inaccuracies by claiming that most of the last 10,000 years and most of the past several thousand years were warmer than today (not true, see Marcott et al. 2013 or PAGES 2K). It omits the surface temperature data from the last 100 years, which show that it was a record warm year. It presents logical flaws by first showing the satellite data of lower tropospheric temperature estimates from 1979 to the present to say that 1998 was warmer than 2015 and then argues that the surface temperature record from the last 100 years was too short to make an argument. What I find most disturbing is that the author paints scientific facts as coming from “activists” and being “doctored”. Clearly an attempt to discredit science. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Key Take-aways : Below is a list of statements made by James Taylor in his article along with comments and replies made by scientists.1. The hottest year on record, in terms of annual global average surface temperature, is 2015. “Forget what global warming activists would lead you to believe—2015 was not even close to the hottest year on record.” Britta Voss Postdoctoral Research fellow, U.S. Geological Survey: This is simply false. 2015 was indeed the hottest year on record. This was rigorously determined by a large group of climate scientists. By calling these scientists “global warming activists,” the author misleadingly implies that the claim is made by a fringe group of non-expert partisans. “So how do global warming activists get away with raising constant alarm and making such outrageous claims as 2015 being the hottest ever? The answer is misleading head-fakes, doctored temperature records, and a compliant media that is more than willing to push the agenda of global warming activists.” James Renwick Professor, Victoria University of Wellington: A wild misrepresentation of reality. Reputable scientists, not activists, compile these records. As for a compliant media, it’s generally the opposite. Many media outlets seem only too pleased to run disinformation pieces like this one, in the name of “balance”. “doctored temperature records” Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: The irony is that the “undoctored” raw temperature records also show that 2015 was the warmest year ever, and actually show a lot more global warming over the past 150 years: 2. Other climatic datasets are consistent with surface temperature data. “Satellite temperature readings going back to 1979 show 1998 was by far the warmest year in the satellite era” James Renwick Professor, Victoria University of Wellington: In that particular record, yes. But what does it measure? An estimate of temperature in a layer above the earth’s surface, derived from observations of radiation into space. It is one of the most adjusted and manipulated records out there. And it is about the only one that shows 1998 as the warmest year. Look at thermometer records, ocean temperature, ice melt, atmospheric moisture content, you name it. They all show the same things, that the earth system is warming steadily. Alexis Berg Research Associate, Harvard University: One wonders here if the author is aware that satellite measurements of the “Lower Atmosphere” (a few km in the atmosphere) do not measure the same thing as surface temperature. So they don’t need to be exactly the same. So in a sense he is comparing apples with oranges here (or mandarines with oranges, if you will). Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: Satellite records do not measure the surface of the earth, where we live; rather, they measure the temperature of the lower atmosphere. They are also subject to large uncertainties due to the need for corrections of factors like orbital decay and coverage / scan time changes. If you look at the uncertainty range of estimates for satellites, it is much larger than that of surface temperatures and really can’t tell us anything about the correctness of the surface temperature trend. “Satellite temperature measurements show 1998 and 2010 were warmer than 2015. Image courtesy of drroyspencer.com.” Victor Venema Scientist, University of Bonn, Germany: The UAH6.0 dataset has not been published yet and scientists have thus not had the opportunity to check these results. UAH6 used very different methods to estimate the temperatures and having a much smaller recent trend than the previous UAH5 dataset. An awkward choice to use UAH6.0 to contrast to the well vetted and more reliable trend estimates of the surface temperature by six different groups world wide. A balanced journalist would at least also show these results. “But we do have other reliable indicators of temperatures before the late 1800s, and the evidence shows temperatures have been warmer than today for most of the past several thousand years, including warmer-than-present temperatures for most of the human civilization time period” James Renwick Professor, Victoria University of Wellington: This is a complete fabrication. The paleoclimate record suggests that the current warmth is unprecedented for at least the last 1400 years. And it is the cause of the current warming (fossil fuel burning) that’s the real story. “we do have other reliable indicators of temperatures before the late 1800s” Julien Emile-Geay Assistant Professor, University of Southern California: How convenient that indicators of temperature are deemed “reliable” to support this fallacy, but unreliable otherwise! The author cannot have it both ways: if the temperature record is reliable prior to the instrumental era (starting in the 1800s), then it is a fortiori reliable afterwards ; and all surface temperature analyses show an extremely strong warming that cannot be explained without man-made forcing, CO2 leading the pack. The paleoclimate record unequivocally shows that temperature maxima coincide with high concentrations of greenhouse gases in the atmosphere (https://www.ipcc.ch/report/ar5/wg1/ Chap 5), which is also the cause of the present warming. 3. El Niño warmth in the eastern equatorial Pacific Ocean contributed to the record warmth, but more importantly, it occurred on top of the long-term global warming trend. “With a record El Niño, we should have experienced record high temperatures. Yet we didn’t.” Eric Guilyardi CNRS Research Director, Université Pierre et Marie Curie & Professor, University of Reading: We certainly did experience a record high temperature (as shown by James Renwick above. A 1 degree celsius (or 2 F) El Niño warming increases the global temperature by 0.1 deg C (or 0.2 F). This year’s El Niño has added about 0.3 deg C driving the global temperature up to 1 C (2 F) above the pre-industrial value. As decades go by the El Niño warming becomes relatively smaller and smaller compared to human induced global warming (+50% in the 90s and just +30% now for the same extreme El Niño). Victor Venema Scientist, University of Bonn, Germany: The last record of the satellite tropospheric temperatures in 1998 was in the year after an El Nino. This may well be the case again. Climate predictions on the short-term are difficult, but it is expected that 2016 will again be a record year. Carl Mears Senior Research Scientist, Remote Sensing Systems (RSS): Calendar years with record temperatures tend to occur in the year following the peak of the El Nino event. This was true for the 1997-1998 and 2009-2010 El Ninos in the satellite data. The fact that 2015 was a record year in the surface temperature record probably means that 2016 will even be a bigger record breaker. “Indeed, if a record strong El Niño cannot bring global temperatures back to the warmth of 1998, what can—and when will that be?” Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: In the surface temperature record, 5 independent groups all find that 2015 far exceeded the temperature of 1998 and was the warmest year on record by a significant margin:

https://science.feedback.org/review/analysis-justin-gillis-2015-hottest-year-global-warming/

1.9

The New York Times, by Justin Gillis, on 2016-01-20.

"2015 Was Hottest Year in Historical Record, Scientists Say"

The article accurately covers the news that the global surface temperature of the planet in 2015 has set a new record, well above any previous measurement. It correctly explains that this new record is due to the combined effects of a strong El Niño event (currently at its peak intensity) in the Pacific, and the continued global warming effect of human emissions of greenhouse gases.See all the scientists’ annotations in contextREVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. James Renwick Professor, Victoria University of Wellington: A very nice, well-written, and factual article, including comment from some of the globe’s leading climate scientists. Pretty much everything in this article is correct and based on peer-reviewed literature. Eric Guilyardi CNRS Research Director, Université Pierre et Marie Curie & Professor, University of Reading: A well documented article with properly quoted top experts. The many facts to consider on this topic are mostly there. Julien Emile-Geay Assistant Professor, University of Southern California: Very balanced article looking at multiple sources of information and interviewing qualified climate scientists. Victor Venema Scientist, University of Bonn, Germany: A joy to read a US newspaper article that accurately reports on the changes in the global temperatures. Rasmus Benestad Senior scientist, The Norwegian Meteorological institute: The article accurately reflects the scientific findings that 2015 is the hottest year on record. Emmanuel M Vincent Research Scientist, University of California, Merced: An accurate and well documented report on the finding that 2015 is the hottest year on instrumental record by a wide margin. Andreas Schmittner Associate Professor, Oregon State University: This article is an excellent example of conveying scientific findings.Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Featured Annotations: Below is a list of a few statements made by Justin Gillis in his article along with comments and replies made by scientists. “When temperatures are averaged at a global scale, the differences between years are usually measured in fractions of a degree” James Renwick Professor, Victoria University of Wellington: Important to understand this. Global/annual average temperatures change by only a tiny fraction from year to year, usually. The jump from 2014 to 2015 is really remarkable. “The strong El Niño has continued into 2016, raising the possibility that this year will, yet again, set a global temperature record” Eric Guilyardi CNRS Research Director, Université Pierre et Marie Curie & Professor, University of Reading: Yes, it is likely that 2016 will also be a near record year for global surface temperature. It is also possible that 2017 will see a La Niña occur (usually following a large El Niño) and that this year will be cooler than 2015 and 2016. This is why detecting climate change and a human influence cannot be done on just a few specific years. Climate scientists consider several decades to average out the naturally variability of the climate. A few very cold days in spring do not imply winter has arrived, do they?

https://science.feedback.org/review/analysis-of-chris-mooney-scientists-say-human-greenhouse-gas-emissions-have-canceled-the-next-ice-age/

1.7

The Washington Post, by Chris Mooney, on 2016-01-13.

"Scientists say human greenhouse gas emissions have canceled the next ice age"

The article presents an accurate account of recently published research which suggests that human-induced global warming will delay the onset of the next ice age by 50,000 years. The research supports the findings of several studies published over the past 15 years, and is consistent with the scientific consensus that human activity is changing the climate with very long-term consequences. Although anthropogenic greenhouse-gas emissions will likely delay the onset of the next ice-age, this is no cause for complacency. As the research notes, at pre-industrial levels of CO2 the planet would not descend into an ice age for another 50,000 years. By contrast, the adverse consequences of global warming are expected to intervene in the coming years, decades and centuries.See all the scientists’ annotations in contextGUEST COMMENTS: Lee Kump Professor, PennState University: That atmospheric carbon dioxide buildup from fossil fuel burning likely will delay the onset of the next glaciation is actually old news; the last emergence of the idea I’m aware of was in 2008, in an article reporting on the work of University of Chicago geoscientist David Archer. The new idea that emerges from the recently published work of Ganopolski et al. is that even if preindustrial levels of 280 ppmv atmospheric CO2 had been sustained to the present and beyond, Earth would have enjoyed an anomalously prolonged warm, interglacial state compared to past interglacials. This finding appears to be robust, but should be evaluated using other earth system models appropriate to study the complicated process of glacial inception. Ken Caldeira Senior Scientist, Carnegie Institution for Science: One thing to be aware of is that this conclusion is not new. For instance, Uchikawa and Zeebe (2008), using a model based on that of Walker and Kasting (1992) came up with the same conclusion, as well as Archer and Ganopolski (2005) who concluded: “We predict that a carbon release from fossil fuels or methane hydrate deposits of 5000 Gton of Carbon could prevent glaciation for the next 500,000 years”. That is not to belittle the present article, who has performed more sophisticated ice sheet modeling than in previous studies. Thus, I would see the new study as giving us greater confidence in conclusions reached by Ganapolski and others in earlier publications.REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. The IPCC’s latest projections for sea level rise by century’s end (e.g. IPCC summary for policymakers) range from 40 cm to 63 cm (or 15″ to 25″). A notable component of that will be due to ice loss. So while our carbon emissions may have initially delayed an ice age, this benefit has been traded for the likelihood of fairly adverse consequences in the future. James Renwick Professor, Victoria University of Wellington: The article is essentially a factual account of the content of the paper, and the material (in the paper and in the WaPo article) covers ideas that have been current for several years, that human-induced greenhouse gases increase has delayed the next ice age. Guillaume Leduc Researcher, CEREGE: The article fairly reports on one of the findings of one article that has recently been published in the scientific journal Nature. On multi-millenia timescales, orbital parameters are considered as pacemakers of ice ages, but now that CO2 has massively been injected in the atmosphere the next ice age which should have already been much into the pipeline is already aborted. The article indeed talks about many things clearly established for decades, but that are still valid. Rasmus Benestad Senior scientist, The Norwegian Meteorological institute: The reporting of the research is objective, although the research itself may be perceived as a bit speculative at this point, even if its plausible. The results are interesting, and need to be confirmed through further work. Alexis Berg Research Associate, Harvard University: This is a nice article which reports on a recent Nature study accurately. However, for the sake of clarity and to avoid potential misinterpretations of such results, the implication that human greenhouse gas emissions have “canceled the next ice age” (in 50,000 years) could have been compared with the implications for near-term global warming. Article continues the tradition of excellence in climate and energy reporting by Chris Mooney and others at the Washington Post. Clearly explains state of the science, though I would have liked to see other anthropogenically and naturally influenced climate forcers (especially aerosols and methane) brought into the discussion.Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time.

https://science.feedback.org/review/analysis-of-matt-ridley-benny-peiser-your-complete-guide-to-the-climate-debate/

-1.5

The Wall Street Journal, by Matt Ridley, Benny Peiser, on 2015-11-27.

"Your Complete Guide to the Climate Debate"

The opinion piece in the WSJ by Matt Ridley & Benny Peiser contains numerous false statements, cherry-picked evidence, and misleading assertions about climate science. It attempts to surround the hard facts about climate change with clouds of uncertainty, even though these facts are agreed to by the scientific academies of every major country in the world and the vast majority of the world’s climate scientists. Facts and/or studies are cherry picked or placed out of context to support the main claim that global warming is not as bad as we feared. For example the assertion that 1.5C of warming would be “beneficial” is one that very few scientists or economists agree with, and is contradicted by the overwhelming weight of evidence in the IPCC’s reports showing that the adverse impacts from climate change will far outweigh the benefits from carbon-dioxide induced greening and other heat-related effects. See below for a list of scientists’ comments on the article’s statements.See all the scientists’ annotations in context GUEST COMMENTS: Steven Sherwood Professor, University of New South Wales: This article peddles the usual false statements masquerading as opinion that we have been seeing for years, and would not be published by a reputable publisher. Most of the scientific statements in the article are false or misleading. Mark Jacobson Professor of Civil and Environmental Engineering, Stanford University: Misleading article with cherry-picked information placed out of context. Eric Wolff Professor, University of Cambridge: The article starts with an obvious logical fallacy: that because people attend a long-planned meeting on climate change, they must think this issue is more important than terrorism. REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Alexis Berg Research Associate, Harvard University: The authors cherry-picks facts and/or studies to try to make the claim that, essentially, global warming is not as bad as we feared. It is a very biased and misleading presentation of the science. Twila Moon Research Scientist, University of Colorado, Boulder: This article is full of convenient cherry-picking and misleading statements. The level of information provided suggests the author is aware of the actual scientific findings that clearly demonstrate the severity of the climate change, but is building false conclusions by cherry picking or making false or unspecific statements. Emmanuel M Vincent Research Scientist, University of California, Merced: The authors omit to mention all the evidence that go against his narrative, this is cherry picking. For instance, the claim that extreme events are not increasing as a response to the ongoing warming of the climate can only be made by not considering the fact that we clearly observe an increase in the severity of both heat waves and heavy rainfall events for instance. William Anderegg Associate Professor, University of Utah: The article contains rampant cherry-picking, misleading statements, and flawed logic. Its presentation of the science is highly biased and inaccurate. Rasmus Benestad Senior scientist, The Norwegian Meteorological institute: The article makes a number of false claims, such as the planet has been warmer during the last 10000 years. The claim that there has been no increase in frequency/intensity of storms/floods/droughts is misleading. There has been increases in extreme precipitation. It’s wrong that the climate sensitivity is “likely to be anything from 1.5 to 4.5 degrees Celsius” – the most likely value is in the central parts of this range, and the fringe values are less probable. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Featured Annotations: Below is a list of statements made by Matt Ridley and Benny Peiser in their Wall Street Journal article along with comments and replies made by scientists. “What precisely makes these world leaders so convinced that climate change is a more urgent and massive threat than the incessant rampages of Islamist violence?” Julien Emile-Geay Assistant Professor, University of Southern California: Studies like this one: Climate change in the Fertile Crescent and implications of the recent Syrian drought. It is one of many examples illustrating how climate stressors may bring societies into conflict over scarce resources. The exact number of future climate victims is impossible to compute, but even by the most conservative estimates it is many orders of magnitude greater than the hundreds (or conservatively thousands) of people killed yearly by terrorist acts. Eric Wolff Professor, University of Cambridge: The article starts with an obvious logical fallacy: that because people attend a long-planned meeting on climate change, they must think this issue is more important than terrorism. Alexis Berg Research Associate, Harvard University: False dichotomy. Climate change and terrorism both can and should be addressed – no matter how one ranks them. By the author’s logic, there couldn’t be a summit on anything else than terrorism right now. Mark Jacobson Professor of Civil and Environmental Engineering, Stanford University: I think the authors are ignorant of the fact that combustion of fossil fuels and solid biofuels today kills between 4-7 million people worldwide EACH year due to the air pollution impacts alone, and these deaths are preventable. This is referenced here. Anthony Barnosky Professor, University of California, Berkeley: Climate change has now been shown to be a contributing cause to the rise of the Islamic State in Syria and a chief national security concern. Happening now are the current refugee crisis and international terrorism spawned by ISIS—a legacy of how climate change helps precipitate conflict as a threat multiplier. Past examples include the Arab Spring uprising (major contributor was a failed crop in Egypt from intense drought), riots in Pakistan and attacks on government officials when drought meant choosing between water to drink and water for hydropower. See recent comments by National security adviser Susan Rice. “world temperatures, because they have gone up only very slowly, less than half as fast as the scientific consensus predicted in 1990” Steven Sherwood Professor, University of New South Wales: This statement is false. The IPCC predicted that warming between 2015 and 1990 would be within about 0.35 and 0.60C; the actual temperature in 2015 will be about 0.5C above the average of years around 1990, so a bit above the middle of the range originally predicted by the IPCC. “the world is barely half a degree Celsius (0.9 degrees Fahrenheit) warmer than it was about 35 years ago” Alexis Berg Research Associate, Harvard University: This kind of statement seems to imply that 0.5 C change in global temperature is negligible. For reference, readers unfamiliar with the order of magnitude of changes in global temperature should be reminded that the difference between today’s global temperature and that of the the Last Glacial maximum (around 20,000 years ago), when ice sheets extended over northern North America and Northern Europe/Asia, is estimated to be only around 4-5 C (e.g., Annan, J. D. and Hargreaves, J. C.: A new global reconstruction of temperature changes at the Last Glacial Maximum) A warming of a few degrees C globally, as projected today under a business-as-usual scenario, is thus something of geological magnitude. Anthony Barnosky Professor, University of California, Berkeley: Global temperature rise has of course been almost double what this article implies if you compare it to preindustrial rather than just the past 35 years. Which means warming has accelerated, not slowed, contrary to the presentation in this article. “Also, it is increasingly clear that the planet was significantly warmer than today several times during the past 10,000 years.” William Anderegg Associate Professor, University of Utah: In addition to likely wrong, this has absolutely no bearing on current human-caused warming. The projections of current warming will greatly exceed temperatures of the past 10,000 years and, more importantly for society and ecosystems, the rate of anthropogenic warming already greatly exceeds any temperature changes in the past 10,000 and even several million years. This rate of warming can have massive societal consequences and will be exceptionally hard for ecosystems and societies to adapt. Eric Wolff Professor, University of Cambridge: This is incorrect. It is notoriously hard to estimate a global average temperature, even today, let alone in the past. However the most comprehensive attempt to do so was by Marcott et al (A reconstruction of regional and global temperature for the past 11,300 years, Science) They found that early Holocene (10000 to 6000 years ago) warmth was followed by a slow cooling of about 0.7 degrees in the last 5000 years. The warming of the last century has taken global average temperature just above the maximum of the early Holocene – albeit so far only for a short period of time. However, it is clear that as warming continues we are entering a prolonged period that is significantly warmer than any period in the last 10000 years. “there has been no increase in frequency or intensity of storms, floods or droughts, while deaths attributed to such natural disasters have never been fewer” Steven Sherwood Professor, University of New South Wales: This statement is not justified as several studies are now reporting increases in severe rains and in storm damages even when non-environmental factors are accounted for. Moreover the authors ignore heat waves which show the clearest increase and kill more people than the ones they mention. Alexis Berg Research Associate, Harvard University: The authors seem to carefully select the types of climate extremes for which, despite projections of increased frequency/intensity of such extremes, observations over recent decades do not allow us to say if present trends are consistent with projections (e.g., droughts). Note that for other types of climate extremes, like temperature extremes, heat waves, or high-intensity rainfall, observations are in agreement with projections and show an increase attributable to human influence- e.g., Fischer and Knutti, 2015, Anthropogenic contribution to global occurrence of heavy-precipitation and high-temperature extremes, Nature Climate Change. “Antarctica is gaining land-based ice, according to a new study by NASA scientists published in the Journal of Glaciology” Twila Moon Research Scientist, University of Colorado, Boulder: This study examined Antarctic ice sheet mass changes until 2008 and presents a single study of Antarctic ice mass. Also, the mechanism indicated for mass change – increased snowfall – is actually a result of a warming atmosphere and an understood change that is consistent with scientific understanding. Perhaps more pertinent, however, is that other studies, including of more recent changes have suggested overall ice loss and, most important, large future ice loss. Recently published articles (Joughin et al. 2014, Rignot et al. 2014) looking at changes on coastal Antarctic ice shelves shows that we have likely already entered a period of major ice shelf retreat, with no mechanisms in sight to stop this retreat over the next 100s of years. The implication of ice shelf and glacier retreat around the Antarctic coast is increased ice loss over the next 10s to 1000s of years. There is a very large body of scientific work examining Antarctic ice sheet mass trends and there is community agreement that future ice loss is expected and will be worse if global temperatures increase more. Jonathan Bamber Professor, University of Bristol: West Antarctica has been losing mass at an increasing rate since the 1990s and, irrespective of what is happening further East, that trend looks set to continue. Going to the other end of the Earth, the Greenland ice sheet has also been losing mass at an accelerating rate since around 1995. Greenland is now the single biggest source of mass to the oceans. These trends at both poles are huge signals that are unequivocal and uncontested. “Sea level continues its centuries-long slow rise—about a foot a century—with no sign of recent acceleration.” Emmanuel M Vincent Research Scientist, University of California, Merced: “Recent” is not a precise term. On climate relevant scale, evidence shows that sea level rise has been accelerating. See for instance the figure below from Jevrejeva et al see also: Church (2008) Understanding global sea levels: past, present and future “But scientists disagree: They say there is great uncertainty” William Anderegg Associate Professor, University of Utah: This is highly misleading. Uncertainty is a fixture of life and is absolutely no reason for not taking policy action. There will always be uncertainty in science (in the form of standard deviations around estimates, for instance), but the scientists fundamentally do not disagree that: 1) humans’ emissions of greenhouse gases are the primary cause of climate change of the past 50-60 years, and 2) consequences are likely to be significantly harmful. See here and here. “It projects that temperatures are likely to be anything from 1.5 to 4.5 degrees Celsius (2.7 to 8.1 degrees Fahrenheit) warmer by the latter part of the century” Victor Venema Scientist, University of Bonn, Germany: This is the range for the Equilibrium Climate Sensitivity, not for the temperature in 2100. This temperature depends on how much we will mitigate climate change for which there are no predictions. This is a wide range of climate sensitivities, but not a sign of disagreement in the scientific community as the op-ed suggests. This range is a fair summary of the evidence for most scientists. Steven Sherwood Professor, University of New South Wales: The authors confuses the “sensitivity” (which they correctly notes ranges from 1.5-4.5C) with the actual warming that we’d have by 2100 (which ranges from 3-6C). There is no way that 3C of warming would be beneficial, and there is no way that we would get away with less than 3C of warming on a business-as-usual emissions pathway. 4C or more of warming would probably render some regions of the planet uninhabitable due to heat stress and cause massive disruption to all societies; 3C might even be enough to do that, we don’t know. “…that is, anything from mildly beneficial to significantly harmful.” Alexis Berg Research Associate, Harvard University: This sentence is very misleading. Even assuming that 1.5 C would be mildly beneficial – which is an unsubstantiated claim at this point – this sentence omits to mention that this more modest warming implies strong and rapid human action to limit greenhouse gas emissions – it is not at all an equally likely outcome of a business-as-usual scenario! A large part in the uncertainties from IPCC projections for the end of the 21st century is due to human behavior, e.g., mainly how much of fossil fuels we will burn (RCPs on the figure below). Note as well that for a business-as-usual scenario (RCP8.5), warming does not stop in 2100, but goes on after that. Steven Sherwood Professor, University of New South Wales: The assertion that 1.5C of warming would be “beneficial” is one that very few scientists or economists would agree with other than Richard Tol. It is true that CO2-induced greening will be beneficial, but how beneficial compared to the problems from greater heat and shifting rainfall patterns is dubious at best. “a new study by a leading climate economist, Richard Tol of the University of Sussex, concludes that warming may well bring gains, because carbon dioxide causes crops and wild ecosystems to grow greener and more drought-resistant.” Victor Venema Scientist, University of Bonn, Germany: It is a good idea to check the source. In this case the link goes to an unpublished manuscript. The manuscript only cites one study with positive impacts. The one of Dr. Tol himself for a 1°C temperature rise, which is a point we have just reached. That impacts for this study become statistically significant only at 3.5°C is because the economic uncertainties are so large. Uncertainties go both ways. William Anderegg Associate Professor, University of Utah: This is an old and largely debunked idea. The best available evidence suggests that while carbon dioxide concentrations do help some crops in some regions, the increases of temperature and drought stress are non-linear and have and will mostly overwhelm positive effects. In fact, climate change has probably driven declines in crop production of 2 of the 4 largest global crops even in the past 30 years. “A key study published in the Journal of Climate this year by Bjorn Stevens of the Max Planck Institute for Meteorology in Hamburg, Germany, found that the cooling impact of sulfate emissions has held back global warming less than thought till now” Victor Venema Scientist, University of Bonn, Germany: That clouds and aerosols are an important reason for the large confidence interval for the climate sensitivity is generally accepted. However, it is an exaggeration to claim that Bjorn Stevens found this. He presented limited evidence that makes a case for future research into this topic. More in general, one should never judge the state of the art based on single papers, especially new papers. “Scientific skeptics are now routinely censored, or threatened with prosecution.” Britta Voss Postdoctoral Research fellow, U.S. Geological Survey: This is misleading as it implies that climate skeptics are being threatened with prosecution because of their skeptical views. In reality, the questions of legality directed at climate skeptics (or, more significantly, fossil fuel companies) are based on concerns of conflict of interest, as scientists and others expressing views on climate science that are contradictory to mainstream consensus have in some cases been found to derive significant funding from fossil fuel companies and other groups that stand to profit from delaying climate policies. The recent example of Willie Soon, the Harvard-Smithsonian researcher who neglected to disclose his funding from fossil fuel companies when publishing research skeptical of established climate science, is a prime example of such a conflict of interest.

https://science.feedback.org/review/forbes-james-taylor-top-10-global-warming-lies-that-may-shock-you/

-2

Forbes, by James Taylor, on 2015-02-09.

“Top 10 Global Warming Lies That May Shock You”

According to Forbes.com, this article has been read more than 110,000 times, making it one of Forbes’ most read article on climate in 2015, and author James Taylor is a popular contributor who writes about energy and environment. So how accurate was this article? Not accurate at all. According to scientists, this article contains numerous factual mistakes and flawed logic about basic science, and the reporting is based on uncredible sources. See the list below for more.See all the scientists’ annotations in context If the link does not work due to the high number of ads on Forbes, install Hypothesis bookmarklet or extension in your browser and switch it on from the article page. GUEST COMMENTS: Peter Reich, Regents Professor and Distinguished McKnight University Professor in Forest Resources, University of Minnesota This is an unusual (as well as misleading) article in that the author mixes sound scientific reasoning with illogical reasoning, and includes patterns and notions supported by data (i.e., facts) with ideas that are wildly inconsistent with the available evidence (falsehoods presented as facts). The misleading aspect comes in because the author picks what are presented as “facts” (sometimes accurate sometimes not accurate whatsoever) and compares these with other “facts” to make a point, but the comparison often has no real relevance to the questions or issues at hand. David Bahr, Associate Professor, Department of Physics, Regis University and Institute of Arctic and Alpine Research, University of Colorado I have rarely read such a misleading and factually inaccurate article. This is not science journalism and has no place in a magazine that purports to be a leading source of reliable news. It cannot qualify as an informed or informative opinion piece, and Forbes does their readers a great disservice by allowing the publication of blatant falsehoods. The author -James Taylor- has no understanding of the important distinctions between polar sea ice (floating on an ocean) and polar ice sheets (grounded on land), and he confuses their role in sea level rise. Despite Taylor’s protestations, the temporary expansion of Antarctic sea ice (which the author embarrassingly confuses with the expansion of an ice sheet) is well understood in the context of climate change, as is the significant reduction of Arctic sea ice which the author misleadingly understates. Taylor wrongly equates the existence of Antarctic sea ice with a lack of sea level rise. In fact, floating and melting sea ice cannot contribute to sea level rise, any more than floating and melting ice cubes can cause a glass of water to overflow. By erroneously focusing on sea ice, the author misdirects the reader and thereby conveniently overlooks the two largest current contributors to sea level rise, thermal expansion of oceans and melting glaciers. Mountain glaciers in particular (including those in Glacier National Park as discussed by Taylor) are receding at an unprecedented and increasing rate that has been repeatedly and undeniably linked to man-made climate change. The glaciers’ rapidly increasing contribution to sea level rise is unassailable. Taylor makes numerous unsubstantiated and entirely non-scientific value judgements about the benefits of climate change, and then he very inappropriately presents these value judgements as logical evidence. Among many egregious examples, the author touts the unproven benefits of increased plant growth as glaciers recede. This is in contrast, for example, to peer-reviewed research showing that as glaciers melt there will be a loss of fresh drinking water to a significant percentage of the world’s population. Taylor’s uncorroborated value judgements should not be presented as if they are on equal footing with facts, and this is a very misleading tactic hiding behind his so-called presentation of science. I could go on at length about the numerous falsehoods, misrepresentations, misdirections, cherry-picked data, cherry-picked research, and appalling logic in this article, but this sampling is sufficient to demonstrate Taylor’s failure to understand and competently write about climate change. REVIEWERS’ OVERALL FEEDBACK: These comments are the overall opinion of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. William Anderegg Associate Professor, University of Utah: This article wins the Olympic gold for cherry-picking data, misleading claims, and a long list of scientifically unsupported assertions. Sarah Perkins-Kirkpatrick Research Scientist, Climate Change Research Centre, The University of New South Wales: Absolutely appalling. Not based on credible scientific publications. Cherry picking of data and results. Use of incorrect or ambiguous language to confuse reader and to support cherry-picked results. Alexis Berg Research Associate, Harvard University: This is a deeply flawed article, scientifically. The author tries to refute a document by the Environmental Defense Fund listing 10 effects of global warming that may be unexpected (“shocking”) to the layman. To do so, he uses logical fallacies, cherry-picks studies and/or data, makes unsubstantiated claims and generally completely ignores the science of climate change and its impacts on natural and human systems. David Lobell Associate Professor, Stanford University: Repeatedly makes the erroneous argument that if something is getting better overall (e.g. health, or food production), then it’s not possible that some factor (e.g. climate) could have a negative effect. By that logic, the readers of Forbes would only worry about the economy after it was already shrinking. Lindsey Nicholson Postdoctoral research fellow, University of Innsbruck: In the sections of my expertise (glaciers, sea-level rise) the article bases its arguments on fundamental misunderstandings of basic science. The difference between sea ice made from freezing sea water, and icebergs discharged from land ice (ice sheets and glaciers) is critical. The former has no impact on sea level, while the latter does. Its a great example of where it is important to understand what the terminology refers to, and also why public articles ought to include definitions of these things to remove all ambiguity. Steven Sherwood Professor, University of New South Wales: False claims made in this article include (just to name a couple in “Lie #1”): Australia’s highest recorded temperature being >50 years ago (this Oodnadatta reading was an incorrectly logged, and was invalidated by the Bureau of Meteorology); heat waves not being attributable to global warming (several recent studies have shown precisely that they are, in the sense that such severe heat could not have occurred without the boost from human-caused global warming). Some claims (e.g. that we’ll just adapt to continued sea level rise) are as lacking in any scientific bases as the claims the author elsewhere criticises. Ilissa Ocko Climate Scientist, Environmental Defense Fund: Incredibly misleading article that takes information out of context and employs flawed reasoning. This article reveals without a doubt that the author is certainly no scientist or expert on the subject, and as such should not be considered a viable source of information. Aaron Bernstein Associate Director of the Center for Health and the Global Environment, Boston Children’s Hospital, Harvard: A reader could be fooled into believing what is written at face value but most claims articulated in James Taylor’s article are false based upon scientific research. Rasmus Benestad Senior scientist, The Norwegian Meteorological institute: Using labels such as “alarmist” does not invite to constructive debate. Furthermore, the statement “remember these are the very best arguments global warming alarmists can make” is highly subjective and not a judgement I think James Taylor is in position to make. For instance “Bats Drop from the Sky” is not one of them! Tobias Sauter Postdoctoral research fellow, University of Erlangen: This article simply ignores the essential principles of good scientific journalism: Truth and accuracy, independence, and impartiality. The article is plagued with inaccurate information and false statements about climate and glacier change. Notes:[1]See the rating guidelines used for article evaluations.[2]Each evaluation is independent. Scientists’ comments are all published at the same time. Featured Annotations: Below is a list of scientists’ comments replying to James Taylor’s statements. “Global warming alarmists’ preferred electricity source – wind power – kills nearly 1 million bats every year (to say nothing of the more than 500,000 birds killed every year) in the United States alone. […] Killing 30 million bats every year in response to dubious claims that global warming might once in a great while kill 100,000 bats makes no sense.” Alexis Berg Research Associate, Harvard University: False dichotomy. The point of transitioning power generation away from fossil fuels is not only to save bats. Also, just to provide some context, it is “estimated that between 89 and 340 million birds die annually from vehicle collisions on U.S. roads” Sarah Perkins-Kirkpatrick Research Scientist, Climate Change Research Centre, The University of New South Wales: Australian bats are fine tuned to a specific threshold – around 42C. Once the temperature is reached they literally DO fall out of trees, and it is primarily lactating mothers and babies this happens to. The more this occurs (as what is projected under anthropogenic climate change), the more they will die, and the less they will be able to recover from what was once a very rare event. See this article, and publications by the author Just Welbergen. “Australia’s highest recorded temperature occurred more than half a century ago, … Indeed, Queensland’s 2014 heat wave paled in comparison to the 1972 heat wave that occurred 42 years of global warming ago. If global warming caused the 2014 Queensland heat wave, why wasn’t it as severe as the 1972 Queensland heat wave?” Alexis Berg Research Associate, Harvard University: Comparing particular dates in times and claiming that global warming should explain everything is a stale and discredited tactic from climate skeptics. What one needs to do is look at robust trends in the data. In his case, it shows that heat waves have increased in frequency/duration since 1950 in some parts of the world (where there is sufficient data to look at such changes), like Europe, Asia, and, yes, South-east Australia. See: Perkins, Alexander & Nairn (2012), Increasing frequency, intensity and duration of observed global heatwaves and warm spells, Geophys. Res. Lett. “Lyme Disease is much more common in northern, cooler regions of the United States than in southern, warmer regions. Asserting, without any supporting data or evidence, that a disease that prospers in cool climates will become more prevalent as a result of global warming defies objective data and common sense. Prof. Kristie L. Ebi, University of Washington: The supporting evidence is one 2008 review of the spatial dynamics of Lyme disease by Killilea et al. The authors did conclude that the presence of forests was associated with increased risk of Lyme disease. They also concluded that the reasons for variations across forested areas are poorly understood, and that significant progress is needed in identifying the determinants of spatial variation in risk and incidence. Between the year 2000 and 2015, there has been 31 publications on Lyme disease and climate change providing significantly more information. The recent US National Assessment Health Chapter concluded that: “Potential impacts of climate change on the transmission of Lyme disease include: 1) changes in the geographic distribution of the disease due to the increase in favorable habitat for ticks to survive off their hosts; 2) a lengthened transmission season due to earlier onset of higher temperatures in the spring and later onset of cold and frost;” Susan E. Pacheco, MD, University of Texas Health Science Center at Houston: 1. That Lyme disease occurs in the northeastern states does not mean that the disease process is driven by a cold environment. Indeed the ticks that spread this disease thrive in humid and relatively warm environments. This, combined with increased human outdoor activities during warmer months help explain most cases of Lyme disease occur in the summer months. It has been established that the geographic distribution of the Ixodes tick has increased with warming temperatures. 2. The authors cite an article by Killilea et al, where it is stated, in the context of spatial dynamics, that “the only environmental variable consistently associated with increased Lyme disease was the presence of forests”. This is taken out of context as climate change is not a variable in this analysis. In a more recent article, Ostfeld, the senior author of the Killilea paper, discusses the association between climate warming and increase in the distribution of the Ixodes tick. “The alarmists’ asserted national security threat depends on assertions that (1) global warming is causing a reduction in food and water supplies and (2) migrations of people to places with more food and water will increase risks of military conflict. Objective facts refute both assertions.” Aaron Bernstein Associate Director of the Center for Health and the Global Environment, Boston Children’s Hospital, Harvard: For starters, many experienced leaders—military, political, and otherwise—are extremely concerned about the threat climate change poses to security. See the American Security Project’s work on climate security. In addition, growing staple crops at higher CO2reduces their nutritional value. While some regions have benefited from recent warming, extreme events associated with climate change have already destabilized the world food system. Models consistently show that climate change will adversely effect crop output. The best available science also shows that even in the past few decades climate change has reduced food production, by as much as 5 billion dollars per year as of 2002. “U.S. Forest Service data show pine beetle infestations have recently declined dramatically throughout the western United States.” William Anderegg Associate Professor, University of Utah: This is true, but it does not reflect a lack of climate change influence on beetles. When one actually examines the US Forest Service reports data, they state that the infestation rates are falling in many regions because they have already killed most of their host pine species. This is hardly good news. Regents Professor Steven W. Running, University of Montana: Climate change has accelerated insect epidemic mortality in western forests. I would refer readers to the 2014 National Climate Assessment, specifically the Chapter on Forests for full details. “Severe storms, floods and agricultural losses may cost a great deal of money, but such extreme weather events—and their resulting costs—are dramatically declining as the Earth modestly warms.” Emmanuel Vincent Founder & Executive Director, Science Feedback: To the best of my knowledge, there is no scientific evidence showing that severe storms and flood are “dramatically declining“. Such a strong statement should be supported by a strong reference. To the contrary, as the atmosphere warms, water vapor content increases, and this is allowing more extreme rainfall events, notably during hurricanes. see eg: Trenberth (2011) Changes in precipitation with climate change “Calling attention to anecdotal incidents of icebergs breaking off the Antarctic ice sheet, while deliberately ignoring the overall growth of the Antarctic ice sheet is a misleading and favorite tactic of global warming alarmists” Martin Truffer, Professor, University of Alaska Fairbanks: The author does not know what he is referring to when he says ‘the Antarctic Ice Sheet’. What has been expanding is the extent of sea ice around Antarctica, not the Antarctic Ice Sheet. While icebergs routinely break off Antarctica, the release of this particular iceberg was significant. Iceberg calving from Pine Island Glacier has been occurring at ever increasing rates, and the line of contact between the glacier and the ocean (the grounding line) keeps retreating. It looks even worse at nearby Thwaites Glacier that is now on the brink of unstable retreat, or has already crossed that threshold. See, for example: Joughin et al (2014). Marine Ice Sheet Collapse Potentially Underway for the Thwaites Glacier Basin, West Antarctica. The basins of Thwaites and Pine Island Glacier hold enough ice to raise global sea level by 1.5 m. “alarmists here are taking overwhelmingly good news about global warming improving plant health and making it seem like this good news is actually bad news because healthier plants mean more pollen.” Susan E. Pacheco, MD, University of Texas Health Science Center at Houston: 1. There is definite scientific evidence demonstrating that warmer temperatures and higher CO2 levels increase the length of the pollen season, and the allergenicity of pollens. 2. Elevated pollen counts have been associated with increase in emergency room visits in patients with asthma.