As fears about climate futures and implications for societies have become more widely expressed, some climate scientists have responded by criticising some of the predictions and conclusions being made, either by other climate scientists, other scholars, or general commentators.
An example of this pushback can be found in the views shared by some climate scientists on the July 2018 Deep Adaptation paper, in a Vice article. Those comments were not specific enough for me to assess or respond to, and so I invited the individual scientists to comment directly on the relevant text of that paper. I am grateful for climate scientists Gavin Schmidt (Director, NASA Goddard Institute for Space Studies, USA) and Dr. Wolfgang Knorr (Lund University, Sweden) for providing such feedback. In this blog I summarise the comments made and my response. As a result of this process, I have identified two minor corrections and two clarifications I will make on the paper. However, none of those are material to the situation we are in and none of the main points are revoked. Moreover, research published subsequently to my paper has provided more support for its argument. Please scroll down to see a point-by-point discussion of the challenges to the climate science part of the Deep Adaptation paper, and my responses.
But first, I want to offer some reflections on the situation in which climate scientists are debating each other as well as other scholars on the worst-case scenarios, and what it means for humanity.
In the face of even non-specialist observations of actual changes right now, as well as an appraisal of the level of human endeavour to tackle climatic changes, one can conclude that the climate situation is bad for species, ecosystems and society. In some cases, responding to that situation by seeking to measure more fully and to debate one’s theories, correlations, models and terminology, can be a form of distraction. Instead of allowing this deeply troubling knowing, people might feel drawn to the idea that ever-more accurate measurement confers a feeling of control, and that being seen as highly correct – and more correct than others – can provide a feeling of security of identity. That approach is incentivised today because projects for measuring our demise can pay the bills, whereas approaches that aim to invite an entirely different worldview, one that seeks to bring attention to and challenge the system and culture that create the problems, is less fundable.
The reality of our climate situation is so huge for humanity, and the current observational data are becoming so alarming, that the temptation to focus one’s discussion on the opinions of some people on the merits of one paper in July 2018 becomes a convenient distraction. Views and research on what one believes is useful to conclude or to share with the public are interesting to discuss, and can draw on social psychology, philosophy, sociology and communications theories. However, such matters are not climate science. Opinions and research on the ways in which human systems will be affected by climatic changes, both directly and indirectly, are interesting to discuss, and can draw on a diverse range of fields and sectoral specialisms, from food security to banking and finance. However, such matters are not climate science. Assuming a climate scientist is the best predictor of how your society will fare within a changing climate is like asking the engineer who made one of the components in your oven to predict how your dinner party will go. Both climate scientists and journalists on climate issues need to be cognisant not only of the limits of climate science but also the limits of their likely worldview on what can be known and how (i.e. their epistemology).
For a more detailed discussion of the unhelpfulness of the public communication of some current climate scientists, see this interview with Dr Wolfgang Knorr. For a recent example of the over-reach of some climate scientists in inaccurately seeking to censor a famous writer’s views on the climate tragedy, hear from top climate scientist Will Steffen here.
Now to a discussion of the criticism and what I have learned and propose as a result.
Surprising levels of Arctic warming
In the DA paper I wrote that the “most surprising warming is in the Arctic.” Dr Gavin Schmidt commented: “how so? Polar amplification has been predicted and observed for decades.” Clearly the question of ‘surprise’ is a subjective one. Many scientists seem to express more surprise than Gavin. For instance, in an article entitled “Arctic warming: scientists alarmed by ‘crazy’ temperature rises” in November 2018, the journalists report top climate scientists expressed not just surprise but also worry. “This is an anomaly among anomalies. It is far enough outside the historical range that it is worrying – it is a suggestion that there are further surprises in store as we continue to poke the angry beast that is our climate” (Michael Mann, Director of the Earth System Science Center at Pennsylvania State University).
Verdict: I was not saying that no scientists analysed polar amplification. The rate of warming in the Arctic surprises and alarms many top climate scientists. Therefore, no correction or clarification needed.
The IPCC under-predicting climate change
I wrote that the IPCC has “a track record of significantly underestimating the pace of change.” Gavin commented that is “not true for most effects.” Whether something is a “track record” and “significant” is a subjective judgement, but my statement is not without scientific support. A study from 2018 provides great detail in how the methodology of the IPCC reporting process leads to “the understatement of existential climate risk” (Spratt and Dunlop, 2018).
Gavin contests some other statements in my paper that relate to this issue of IPCC underpredicting the pace of change. On the matter of sea level rise, I wrote “Stating a figure per year implies a linear increase, which is what has been assumed by IPCC and others in making their predictions.” Gavin replied: “not true at all. (if it were, the further rise to 2100 would be about 10 inches – all predictions are higher than that – some considerably so).” The linear prediction I referred to was within a 10-year period. I gave a misleading impression that each ten-year period would not have an increased rate of increase. However, the point I am making is correct – the IPCC has consistently underpredicted sea level rise.
I also refer to the models that the IPCC used for its assessments. “The observed phenomena, of actual temperatures and sea levels, are greater than what the climate models over the past decades were predicting for our current time.” Gavin comments: “Again, not true” and provides a diagram that shows in 2000 the averaged prediction of models for the year 2019 was almost a 0.6 degree warming above a baseline of temperatures between 1980 and 1999. That baseline was about 0.35C above preindustrial levels. From the graph Gavin links to, in 2000 the models predicted, once averaged, about a 0.6 rise above that baseline for 2019, or a total of about 0.95C above preindustrial temperatures. Actual temperature recordings suggest 2019 was about 1.1 C above preindustrial levels. That means the models were fairly accurate, but on average they under-predicted by about 0.16 degrees.
Verdict: I can correct and remove the claim that there was only linear prediction of sea level rise in IPCC reports, but can also state their under-estimate of sea level rise. An additional reference to the relevant evidence will be useful in future publications. I can clarify that the model projections from 20 years ago were only slightly below current global temperatures. However, the argument that IPCC has under-predicted the levels of current warming remains true. In addition, the warnings from IPCC – and the climate models they used – did not predict either the levels of weather volatility or the possible initiation of climate tipping points at the current level of warming. These matters are more important for understanding whether IPCC has been providing a valid framework for policy deliberation.
Exponential changes and runaway climate change
In the paper I wrote: “Non-linear changes are of central importance to understanding climate change, as they suggest both that impacts will be far more rapid and severe than predictions based on linear projections…” Gavin comments: “which projections would those be? All GCM predictions are fundamentally non-linear.” My statement simply explains how exponential change presents more risk of destabilising a system than linear change. Such exponential changes can be seen through the observation of current phenomena, such as sea level, permafrost melt and so on. I was not discussing computer simulation models in this statement.
I ended that sentence with “in other words – ‘runaway climate change.’” Gavin commented: “This is nonsense. Non-linearity (which is ubiquitous) is not synonymous with ‘runaway’ climate change.” Key here is what we mean by ‘runaway climate change’. One interpretation of that concept is that the Earth self-heats in ways that are not able to be stopped, and perhaps not even slowed, by human response. In climate science, these are called ‘tipping points.’ The latest research from the climate scientists who study these tipping points has found that “we might already have crossed the threshold for a cascade of inter-related tipping points,” that would begin taking the Earth to a far hotter state. The researchers concluded that of the 15 potential tipping points they identified in 2008, seven now show signs of being active, meaning they may have already tipped into self-reinforcing and irreversible change. That is along with two new ones they have added to their list (Lenton, et al, 2019). So with nine tipping points in total already active and inter-relating, ‘runaway’ change is a reasonable term to use for that situation. In my sentence, I emphasised how rates of change that are no longer correlated with human action means runaway climate change. I was not saying non-linearity means runaway. Therefore, the statement was not “nonsense.” To focus on choice of phrases on this topic might distract us from the magnitude of the situation in the real world.
Verdict: No clarification or correction. Adding a reference to the new findings from scientists will be useful in future publications.
On heating impact of Arctic Ice loss
In the paper I cite one of “the most eminent climate scientists in the world, Peter Wadhams.” Gavin replied simply: “LOL.” Wadhams is a Professor of Ocean Physics at the University of Cambridge. I cited him predicting that summer Arctic sea ice could be gone in the “next few years.” Gavin replied: “he has been predicting this for a decade (based on nothing more than an exponential fit). It’s not credible.” The dismissal of this prediction not being credible is questionable for two key reasons. First, an exponential fit i.e. projection, is based on observational data, and therefore is a widely used approach and emphasises the importance of observational data i.e. what’s actually happening, rather than sophisticated computer models with multiple relationships between multiple variables. People who work on computer modelling and are interested in the finer points of disagreement in physics may consider simple exponential fits to be less robust, but that is merely a matter of convention within a scientific field. Gavin does recognise that this situation with the Arctic is “huge (if true).”
Verdict: There is no need for a correction or clarification. However, I could cite some of the critics of Prof Wadhams’ work but also the importance of including his warning of the extent of the amplification effect is essential to include for a responsible assessment of a dangerous situation.
On whether more energy means more volatility
I wrote that: “already we see impacts on storm, drought and flood frequency and strength due to increased volatility from more energy in the atmosphere (Herring et al, 2018).” Gavin wrote “urban myth.” There are a number of ways more energy leads to more volatility, but not through a general rise, as Gavin rightly challenges here. One way is from warmer waters fuelling the strength of hurricanes. Another way depends on how the greater amount of energy is being distributed. What is happening currently is more energy is being trapped in the polar regions which means the temperature gradient with the lower latitudes drops and therefore the jet streams weaken and become more wavy, thereby creating more blocks of high pressure that lead to extreme weather (Kornhuber, et al 2019).
Verdict: I will provide a clarification that the differential distribution of the increased energy is the important factor leading to higher volatility. This change does not undermine the point – we are experiencing greater volatility due to climate change.
On human impacts of changes
In the paper I said “…the rates of sea level rise suggest they may be soon become exponential (Malmquist, 2018), which will pose significant problems for billions of people living in coastal zones (Neumann et al, 2015).” Gavin commented “order of magnitude too high. More like 100 million within 1 meter of high tide.” He is partly correct. Although nearly 2.4 billion people, live within 100 km (60 miles) of an oceanic coast, there are far less who live at elevations that will be affected. Dr Wolfgang Knorr notes “Under high emissions, CoastalDEM indicates up to 630 M people live on land below projected annual flood levels for 2100, and up to 340 M for mid-century, versus roughly 250 M at present.”
I wrote about predictions of “declines in the yields of rice, wheat, and corn in China by 36.25%, 18.26%, and 45.10%, respectively, by the end of this century (Zhang et al, 2016).” Gavin commented “under no adaptation scenarios,” which may invite us to consider that the impacts might be less. Yes, they might be less, but they might also be worse. Studies on food security that came out in 2019 raise further alarm about impacts in the nearer term (e.g. Gaupp, et al, 2019). Studying food systems, which include agriculture, logistics, processing, retail and so on, is highly complex. To emphasise how adaptation might help instead of, for instance, mentioning how production losses could be amplified by market dynamics, into major shortages, is a subjective choice. I have been researching food systems more closely and will share information on that in the coming weeks.
Verdict: No correction or clarifications required. However, I will release an occasional paper about how societal disruptions will likely occur.
On carbon budgets and future warming predictions
In the paper I wrote “scientists who estimated that existing CO2 in the atmosphere should already produce global ambient temperature rises over 5°C and so there is no carbon budget – it has already been overspent (Wasdell, 2015).” Gavin commented “this is nonsense as well.” I looked again at the sources, and the critics of the author’s methods and agree that it is not a widely shared view, which would have been appropriate to note in the paper. However, the two points remain. First, Dr Wolfgang Knorr has recently estimated that the carbon budget will be spent by 2025. “The problem is the high uncertainty surrounding earth system feedbacks. If you take the conservative estimate of the IPCC (100Gt for permafrost and arctic methane), then at current trends the IPCC’s 2/3 change of staying within +1.5C will be exhausted in about 5 years time. If you include a wider range of positive feedbacks it is quite likely the budget has already been exhausted.” Whether the budget is “already” spent or current emissions trajectories mean that we know now that it will be spent in the next 5 years, are not significant differences for the main point about the atmosphere already having too much carbon in it for a safe climate.
The second issue here is the prediction of warming. The global ambient warming of 5 degrees from current levels is not a consensus view of science, and I didn’t state that it was. Mainstream climate researchers have concluded that climate change is and will happen much faster than the IPCC predicted (Xu et al, 2018). What is also important since I wrote the paper is what the latest and most advanced models are projecting. They are suggesting that on current emissions pathways we are heading for over 6 degrees of warming by the end of the century (Johnson, 2019). That is a catastrophic level of warming which could threaten the survival of the human race.
Verdict: I should clarify that Wasdell (2015) is not offering a mainstream view, and instead include information from mainstream scientists, including that which came out after my DA paper, who are suggesting similar outlooks.
The risk of methane release
I wrote “In 2017 scientists working on the Eastern Siberian sea shelf, reported that the permafrost layer has thinned enough to risk destabilising hydrates (The Arctic, 2017). Gavin commented that “this is totally misleading. The ESSS permafrost is a relic of the last ice age, and has been thawing since it was inundated around 7-8000 years ago. None of the claims of the Shakhova group demonstrate any response to current warming trends. Plus their estimates of available hydrates are vastly overstated.” In the paper I discuss the variety of scientific theories on this topic, including the respected and experienced Shakhova group of researchers. Given the strong differences of opinion, as illustrated by Gavin’s reply, in my paper I emphasise the importance of real time observations of what is happening in both the sub sea and above ground permafrost. For ground-level permafrost release, this is happening at concerning rates that were never predicted to occur by now. For seafloor permafrost the data is uncertain.
However, Gavin rejects an emphasis on real time measurements, saying that “retrievals are not reliable.” Given the severity of the risk, I disagree with him that we do not include real time observations in our assessments of this situation.
Verdict: I did not conclude that methane is being released from sea floor permafrost but that some science suggests it is possible at scale, so we should look at recent measurements. I also noted later in the paper that shock and anxiety is a normal emotion for when discovering this situation is even possible. I do not see any reason to change anything in my paper on the matter.
On whether models ignored methane
In the paper I wrote that methane “was ignored in most of the climate models over the past decades.” Gavin commented: “not true. It is a standard greenhouse gas (included with CO2, CFCs and N2O) in all models since at least CMIP3.” This statement was a mistake in my paper. What I should have said is that prior to 2005, many models did not include methane and the modelling used for IPCC since then have not been including the amounts of methane that recent research is finding and predicting. For instance, Farquharson, et al (2019), Lamarche-Gagnon, et al (2019) and Nisbet, et al. (2019).
Verdict: I can make a correction that since 2005 models included methane but not to the levels that current research suggests is suitable, and that the new data challenges the idea that there is a carbon budget as assumed by the Paris agreement (Nisbet, et al, 2019).
I will add a box of minor corrections and clarifications to a new version of the Deep Adaptation paper for download. However, currently none of the conclusions from the climate science section of the paper need to be retracted. Instead, it is important to focus on how to expand the conversation about how humanity can reduce harm and save what we can in the face of disruptive climate change. That work continues with the Deep Adaptation Forum. I will also help provide further guidance on the mechanisms by which climate stresses society in a forthcoming paper. I want to express my gratitude for Dr Schmidt and Dr Knorr for taking the time to comment on specifics of the original DA paper.
Farquharson, L. M., Romanovsky, V.E., Cable, W. L., Walker, D. A., Kokelj,S. V., & Nicolsky, D. (2019). “Climate change drives widespread and rapid thermokarst development in very cold permafrost in the Canadian High Arctic. Geophysical Research Letters, 46. Available at https://doi.org/10.1029/2019GL082187
Gaupp F, Hall J, Mitchell D, & Dadson S (2019). Increasing risks of multiple breadbasket failure under 1.5 and 2 °C global warming. Agricultural Systems 175: 34-45. DOI:10.1016/j.agsy.2019.05.010, which is downloadable at http://pure.iiasa.ac.at/id/eprint/15923/1/AS_manuscript_revised_2nd.pdf and published at https://www.sciencedirect.com/science/article/pii/S0308521X18307674
Henley, B. J. & King, A. D. Geophys. Res. Lett. 44, 4256–4262 (2017) https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2017GL073480
Johnson, J. (2019) ‘Terrifying’ New Climate Models Warn of 6-7°C of Warming by 2100 If Emissions Not Slashed, Common Dreams, September 17, 2019. https://www.commondreams.org/news/2019/09/17/terrifying-new-climate-models-warn-6-7degc-warming-2100-if-emissions-not-slashed
Kornhuber, Kai, Dim Coumou, Elisabeth Vogel, Corey Lesk, Jonathan F. Donges, Jascha Lehmann and Radley M. Horton (2019) “Amplified Rossby waves enhance risk of concurrent heatwaves in major breadbasket regions”, 9 December 2019, Nature Climate Change. DOI: 10.1038/s41558-019-0637-z https://www.nature.com/articles/s41558-019-0637-z.epdf?
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Nisbet, E. G., et al. (2019) “Very strong atmospheric methane growth in the four years 2014-2017: Implications for the Paris Agreement” Global Biogeochemical Cycles Vol. 3 Issue 33 pp 318-342, Available at https://doi.org/10.1029/2018GB006009
Spratt, D., & Dunlop, I. (2018) “What lies beneath: The Understatement Of Existential Climate Risk” National Centre for Climate Restoration. Available from https://www.breakthroughonline.org.au (Accessed Jan 1 2019)
Xu, Y, V. Ramanathan and D. G. Victor (2018) Global warming will happen faster than we think, in Nature, https://www.nature.com/articles/d41586-018-07586-5