by Judith Curry
In private, climate scientists are much less certain than they tell the public. – Rupert Darwall
I was invited to write a Foreword to the essay, which provides context for the essay:
While the nations of the world met in Bonn to discuss implementation of the Paris Climate Agreement, the Trump administration was working to dismantle President Obama’s Clean Power Plan and to establish a climate “red team” to critically evaluate the scientific basis for dangerous human-caused climate change and the policy responses.
The mantra of “settled science” is belied by the inherent complexity of climate change as a scientific problem, the plethora of agents and processes that influence the global climate, and disagreements among scientists. Manufacture and enforcement of a “consensus” on the topic of human-caused climate change acts to the detriment of the scientific process, our understanding of climate change, and the policy responses. Indeed, it becomes a fundamentally anti-scientific process when debate, disagreement, and uncertainty are suppressed.
This essay by Rupert Darwall explores the expressions of public certainty by climate scientists versus the private expressions of uncertainty, in context of a small Workshop on Climate organized by the American Physical Society (APS). I was privileged to participate in this workshop, which included three climate scientists who support the climate change consensus and three climate scientists who do not—all of whom were questioned by a panel of distinguished physicists.
The transcript of the workshop is a remarkable document. It provides, in my opinion, the most accurate portrayal of the scientific debates surrounding climate change. While each of the six scientists agreed on the primary scientific evidence, we each had a unique perspective on how to reason about the evidence, what conclusions could be drawn and with what level of certainty.
Rupert Darwall’s essay provides a timely and cogent argument for a red/blue team assessment of climate change that provides both sides with an impartial forum to ask questions and probe the other side’s case. Such an assessment would both advance the science and open up the policy deliberations to a much broader range of options.
Here are some highlights from the full essay (but you’ll want to read the whole thing!):
Introduction. How dependable is climate science? Global warming mitigation policies depend on the credibility and integrity of climate science. In turn, that depends on a deterministic model of the climate system in which it is possible to quantify the role of carbon dioxide (CO2) with a high degree of confidence. This essay explores the contrast between scientists’ expressions of public confidence and private admissions of uncertainty on critical aspects of the science that undergird the scientific consensus.
Instead of debating, highlighting and, where possible, resolving disagreement, many mainstream climate scientists work in a symbiotic relationship with environmental activists and the news media to stoke fear about allegedly catastrophic climate change, providing a scientific imprimatur for an aggressive policy response while declining to air private doubts and the systematic uncertainties.
Two Statements, Two Perspectives. Two statements by two players in the climate debate illustrate the gap between the certainty that we are asked to believe and a branch of science shot through with uncertainty. “Basic physics explains it. If global warming isn’t happening, then virtually everything we know about physics is wrong,” states Jerry Taylor, president of a group that advocates for imposing a carbon tax on the United States. In so many words, Taylor says that the case for cutting carbon dioxide emissions is incontrovertible: Science demands conservatives support a carbon tax.
The second statement was made by an actual climate scientist, Dr. William Collins of the Lawrence Berkeley National Laboratory. Speaking in 2014 at an American Physical Society climate workshop, Collins, who was a lead author of the chapter evaluating climate models in the 2013 Intergovernmental Panel on Climate Change’s (IPCC) Fifth Assessment Report, talked of the challenges of dealing with several sources of uncertainty. “One of them is the huge uncertainties even in the historical forcings,” he said. Commenting on the “structural certainty” of climate models, he observed that there were “a number of processes in the climate system we just do not understand from basic physical principles. … We understand a lot of the physics in its basic form. We don’t understand the emergent behavior that results from it.”
The 2014 APS Climate Workshop: A Perfect Venue for Open Debate. Things are different when climate scientists are on the stand alongside their peers who know the science as well as they do, but disagree with the conclusions they draw from the same body of knowledge. Such open debate was on display at the 2014 American Physical Society climate workshop, which took place in Brooklyn and lasted just over seven hours. A unique event in the annals of the climate debate, it featured three climate scientists who support the climate change consensus and three climate scientists who do not. That format required an unusual degree of honesty about the limitations of the current understanding of the climate system. For the most part, circumspection, qualification, and candid admissions of lack of knowledge were the order of the day.
The IPCC’s Use and Abuse of Climate Models. The discussion in Brooklyn shows that putting the words “gold standard” and “IPCC” in the same sentence demonstrates a serious misunderstanding of the reliability of IPCC-sanctioned climate science.
“It’s clouds that prevent us from fundamentally in some reductive fashion understanding the climate system,” Princeton Atmospheric and Oceanic Sciences Professor Isaac Held, senior research scientist at the National Oceanic and Atmospheric Administration’s (NOAA) Geophysical Fluid Dynamics Laboratory, declared from the IPCC climate consensus bench. Collins made a similar point toward the end of the session. “My sense, to be honest with you, is that, and I think this all makes us a little bit nervous,” he said; “climate is not a problem that is amenable necessarily to reductionist treatment.”
Yet the IPCC’s top-line judgment in its Fifth Assessment Report—that it is “extremely likely” that the human emissions of greenhouse gases are the dominant cause of the warming since the mid-20th century—was described by Dr. Ben Santer of the Lawrence Livermore National Laboratory as likely to be conservative. The basis for this claim? General circulation models.
Santer’s claim would have sounded impressive if earlier in the day Collins had not presented charts showing GCMs performing poorly in reproducing temperature trends in the first half of the 20th century. Lindzen asked, what in the models causes the 1919-1940 warming? “Well, they miss the peak of the warming,” Held replied. While the IPCC is extremely certain that the late 20th century warming is mostly man-made, to this day it cannot collectively decide whether the earlier warming, which is of similar magnitude to the one that started in the mid-1970s, is predominantly man-made or natural. “It actually turns to be very hard to use the past as prologue,” Collins conceded before explaining: “We do not have a first principles theory that tells us what we have to get right in order to have an accurate projection.” And, as Held noted, over the satellite era from 1979, GCMs over- estimated warming in the tropics and the Arctic.
Steven Koonin, chairing the APS workshop, read an extract from chapter 10 of the IPCC’s Fifth Assessment Report. Model-simulated responses to forcings—including greenhouse gas forcings—“can be scaled up or down.” To match observations, some of the forcings in some of the models had to be scaled down. But when it came to making the centennial projections, the scaling factors were removed, probably resulting in a 25 to 30 percent over-projection of the 2100 warming, Koonin said. Only the transcript does full justice to the exchange that followed.
Dr. Koonin: But if the model tells you that you got the response to the forcing wrong by 30 percent, you should use that same 30 percent factor when you project out a century.
Dr. Collins: Yes. And one of the reasons we are not doing that is we are not using the models as [a] statistical projection tool.
Dr. Koonin: What are you using them as?
Dr. Collins: Well, we took exactly the same models that got the forcing wrong and which got sort of the projections wrong up to 2100.
Dr. Koonin: So, why do we even show centennial-scale projections?
Dr. Collins: Well, I mean, it is part of the [IPCC] assessment process.
“It is part of the assessment process” is not a scientific justification for using assumptions that are known to be empirically wrong to produce projections that help drive the political narrative of a planet spinning toward a climate catastrophe.
Climate Science and Falsifiability. A lively exchange developed between Christy and Santer. Georgia Tech’s Dr. Judith Curry, the third member of the critics’ bench, had crossed swords with Santer on whether the IPCC’s statement that more than half the observed warming was anthropogenic was more than expert judgment. In subsequent testimony to the House Science, Space, and Technology Committee, Curry explained:
Science is often mischaracterized as the assembly and organization of data and as a collection of facts on which scientists agree. Science is correctly characterized as a process in which we keep exploring new ideas and changing our understanding of the world, to find new representations of the world that better explain what is observed. … Science is driven by uncertainty, disagreement, and ignorance—the best scientists cultivate doubt.
Curry’s approach to science stands firmly on the methods and philosophical standards of the scientific revolution—mankind’s single greatest intellectual achievement.
Politicized Science vs. Red/Blue Team Appraisals. The APS workshop provides the strongest corrective to date to the politicized IPCC process. It revealed the IPCC’s unscientific practice of using different assumptions for projecting future temperature increases from those used to get models to reproduce past temperature. One need not be a climate expert to see that something is seriously amiss with the near certainties promulgated by the IPCC. “I have got to say,” Koonin remarked to climate modeler William Collins, “that this business is even more uncertain than I thought, uncertainties in the forcing, uncertainties in the modelling, uncertainties in historical data. Boy, this is a tough business to navigate.”
Koonin came away championing Christy’s idea of a red/blue team appraisal, a term drawn from war-gaming assessments performed by the military rather than from politics, which EPA Administrator Scott Pruitt has since adopted.
A revealing indicator of its potential value is the response to it. A June 2017 Washington Post op-ed, condemned calls for red/blue team appraisals as “dangerous attempts to elevate the status of minority opinions.”
Conclusion: Climate Policy’s Democratic Deficit. Open debate is as crucial in science as it is in a democracy. It would be contrary to democratic principles to dispense with debate and rely on the consensus of experts. The latter mode of inquiry inevitably produces prepackaged answers. But, as we have seen, relying on “consensus” buttresses erroneous science rather than allow it to be falsified.
The IPCC was created to persuade, not provide objectivity and air disagreement. By contrast, the APS workshop gave both sides an impartial forum in which they could ask questions and probe the other side’s case. In doing so, it did more to expose the uncertainty, disagreement, and ignorance—to borrow Judith Curry’s words—around climate science than thousands of pages of IPCC assessment reports.
EPA Administrator Scott Pruitt’s proposal for red/blue team assessment is a logical progression from the workshop. The hostile reaction it elicited from leading consensus advocates strongly suggests that they fear debate. Climate scientists whose mission is to advance scientific understanding have nothing to fear and much to gain. Those who seek to use climate science as a policy battering ram have good reason to feel uncomfortable at the prospect. The biggest winner from a red/blue team assessment will be the public. If people are to buy into policies that will drastically alter their way of life, they should be fully informed of the consequences and justifications. To do otherwise would represent a subversion of democracy.
I’m very pleased to have this opportunity to revisit the APS Workshop on Climate Change, and am delighted to see that a journalist of Darwall’s caliber interpreting this. Drawl’s essay provides an eloquent argument in support of a climate red team, perhaps more so than what I, Steve Koonin or John Christy have provided.
The thing that really clicked in my brain was this statement by Bill Collins:
We understand a lot of the physics in its basic form. We don’t understand the emergent behavior that results from it.
Trying to leverage our understanding of the infrared emission spectra from CO2 and other ‘greenhouse’ gases into a ‘consensus’ on what has caused the recent warming in a complex chaotic climate system is totally unjustified — this is eloquently stated by Bill Collins.
My key take away conclusion from the APS Workshop is that the scientists on both sides are considering the same datasets and generally agree on their utility (the exception being the 2 decade debate between Santer and Christy on the uncertainties/utility of the satellite derived tropospheric temperature data). There is some disagreement regarding climate models, although I can’t say that I disagreed with much if anything said by Held and Collins in this regard.
The real issue is the logics used in linking the varied and sundry lines of evidence into drawing conclusions and assessing the uncertainties and areas of ambiguity and ignorance. I don’t think that any of the 6 scientists were using the same chain of reasoning about all this, even among scientists on the same ‘sides’.
Darwall’s essay deserves to be widely read. Here’s to hoping that it will reignite the discussion surrounding the climate red team.