by Judith Curry
Tough days on The Hill for the enforcers of the climate consensus.
While EPA Administrator Scott Pruitt has been taking most of the ‘heat’ for the Trump administrations climate policy, this past week Energy Secretary Rick Perry and Interior Secretary Ryan Zinke stepped into the fray.
Rick Perry was asked in an interview on CNBCs Squawk Box whether he believed carbon dioxide was “the primary control knob for the temperature of the Earth and for climate.” Perry responded: “No, most likely the primary control knob is the ocean waters and this environment that we live in.” “. . . the fact is this shouldn’t be a debate about, ‘Is the climate changing, is man having an effect on it?’ Yeah, we are. The question should be just how much, and what are the policy changes that we need to make to effect that?”
At the same Congressional hearing, Senator Franken repeatedly asked Zinke if he could “tell me how much warming government scientists predict for the end of this century under a business-as-usual scenario?” Zinke stated: “I don’t think government scientists can predict with certainty,” he said. “There isn’t a model that exists today that can predict today’s weather given all the data.”
Response from the consensus police
From the eenews article about Zinke’s testimony:
Kevin Trenberth, a senior scientist at the National Center for Atmospheric Research in Colorado, said Zinke’s explanation was “a stupid and ignorant answer.”
Climate models, he said, are getting better. The simulations increasingly line up with observed changes.
“Well, all models are wrong, but some are useful,” Trenberth said. “Weather models aren’t able to accurately predict if it’ll be sunny or rainy two weeks from now because they are sensitive to small disruptions.
“But the patterns of weather may still be predictable in the same sense that summer is different than winter,” he added. “And that is what climate is all about: determining the effects of the sun, the atmospheric composition, the oceans, the ice and … looking for systematic influences.”
While climate modeling and weather forecasting are similar, they rely on different sets of data and measure vastly different time scales, said Gavin Schmidt, director of the NASA Goddard Institute for Space Studies.
When looking over long periods of time, the external drivers of climate — things like how much carbon dioxide is in the atmosphere trapping heat, and how many trees have been cut down and are no longer sequestering greenhouse gases — can be used to make statistical predictions about the climate, Schmidt said.
JC comment: Zinke’s statement is true. Trenberth is a scientific bully/thug for calling Zinke’s answer stupid and ignorant, especially when both Trenberth and Schmidt basically admit that the models can’t predict the future.
In response to Perry’s statement, the Executive Director of the American Meteorological Society (AMS), Keith Seitter, said in a letter to Perry:
While you acknowledged that the climate is changing and that humans are having an impact on it, it is critically important that you understand that emissions of carbon dioxide and other greenhouse gases are the primary cause.
This is a conclusion based on the comprehensive assessment of scientific evidence. It is based on multiple independent lines of evidence that have been affirmed by thousands of independent scientists and numerous scientific institutions around the world.
In the interview you also mentioned that it should be quite acceptable to be a skeptic about aspects of the science. We agree, and would add that skepticism and debate are always welcome and are critically important to the advancement of science.
In climate science unresolved questions remain—issues that currently lack conclusive evidence. However, there are also very solid conclusions that are based on decades of research and multiple lines of evidence. Skepticism that fails to account for evidence is no virtue. As noted above, the role of carbon dioxide and other greenhouse gases as the primary driver for the warming the Earth has experienced over the past several decades is extremely well established.
Roy Spencer has an article in Fox News responding to Seitter’s letter, excerpts:
Basically, Perry is saying he believes nature has a larger role than humans in recent warming. I, too, believe the oceans might well be a primary driver of climate change, but whether the human/nature ratio is 50/50, or less, or more than that is up for debate. We simply don’t know.
So, while Sec. Perry goes against the supposed consensus of scientists, what he said was not outlandish, and it wasn’t a denial of a known fact. It was a valid opinion on an uncertain area of science.
Seitter calls the claims in his letter “indisputable.” Really? In my opinion, the AMS view (which draws upon the U.N. IPCC view) is much more definitively stated than the evidence warrants.
Sure, all the scientific institutions are on the bandwagon, with politically savvy committees agreeing with each other. They are, in effect, being paid by the government to agree with the consensus through billions of dollars in grants and contracts.
So, maybe I can ask the AMS: Just what percentage of recent warming was natural in origin? None? 10%? 40%? How do you know? Why was the pre-1940 warming rate—caused by Mother Nature—almost as strong as recent warming?
Pielke Senior tweets:
What [Keith Seitter’s letter] further documents, is how small cabal of individuals controls information flow to policymakers.
Mike Smith tweets:
It is wrong for a small group of AMS executives to play politics on behalf of the society’s members w/o a vote of the society.
PolitiFact did a fact check on Rick Perry’s statement. Excerpts:
Perry’s claim flies in the face of settled science.
The world’s leading authority on climate change, the Intergovernmental Panel on Climate Change, has concluded that human activity is “extremely likely” to be the main driver of warming since the mid 20th century.
While it’s still possible to find dissenters, scientists around the globe generally agree with this conclusion.
“We have concluded close to all of the recent trends in global temperature is due to human activity, and CO2 is the dominant factor,” Schmidt said, referring to carbon dioxide.
Perry’s claim contradicts settled science. While natural factors certainly affect the climate, human factors are the main contributor to global warming, and carbon dioxide has acted as the “primary control knob” governing the earth’s relatively recent uptick in temperature.
We rate Perry’s statement False.
On June 20, John Kruzel, the author of the Politifact article, sent me an email:
We’re looking into Energy Secretary Rick Perry’s recent claim that the main cause of climate change is most likely “the ocean waters and this environment that we live in.” We’ve asked the Department of Energy why Perry disagrees with the IPCC that human activity is the main cause of climate change; we’ve received no response so far.
I’d be grateful if you’d consider the following questions:
JC question: So what are we to conclude from PolitiFact’s failure to even mention or consider my responses, after explicitly asking for them?
Red Team/Blue Team
Santer, Emanuel and Oreskes have an op-ed in the WaPo criticizing calls for red team/blue team approach, which was reiterated in Rick Perry’s testimony. Excerpts:
Such calls for special teams of investigators are not about honest scientific debate. They are dangerous attempts to elevate the status of minority opinions, and to undercut the legitimacy, objectivity and transparency of existing climate science.
Critiques of this consensus have been offered up for decades. Each critique is often presented as a kind of smoking gun — one piece of evidence that falsifies all other evidence and understanding. There are many examples of such putative smoking guns. The ballistics of each gun has been carefully tested by thousands of scientists around the world. The “natural causes” gun doesn’t fit the overwhelming evidence of human-caused climate change. The “no warming” gun is inconsistent with reality.
If you’re a climate scientist, you’ve likely spent years of your career going down such rabbit holes, evaluating “natural causes” and “no warming” claims. You’ve considered and debated these claims. You’ve put them through their paces. They do not hold up to available evidence. Only the most robust findings survive peer review and form the basis of today’s scientific consensus.
Science has substantially improved our understanding of the physical climate system, the reality of human-caused warming, and the likely climatic outcomes if we do nothing to reduce emissions of greenhouse gases. Rejecting this tried and tested understanding would constitute real “advisory malpractice,” and would delay effective action to address human-caused climate change.
In the case of climate science, we choose to place our trust in peer review and in the scientific community — not in teams appointed by Koonin or Pruitt.
Pielke Sr tweets:
[The WaPo op-ed] is really about suppression of diversity of scientific views wrt climate science
The problem with Santer et al.’s argument about natural variability is starkly illustrated by this recent paper by Santer et al. (which arguably deserves its own post since it is an interesting and important paper, but I am short of time these days):
Santer, B. D. et al. (2017) Causes of differences in model and satellite tropospheric warming rates
Abstract. In the early twenty-first century, satellite-derived tropospheric warming trends were generally smaller than trends estimated from a large multi-model ensemble. Because observations and coupled model simulations do not have the same phasing of natural internal variability, such decadal differences in simulated and observed warming rates invariably occur. Here we analyse global-mean tropospheric temperatures from satellites and climate model simulations to examine whether warming rate differences over the satellite era can be explained by internal climate variability alone. We find that in the last two decades of the twentieth century, differences between modelled and observed tropospheric temperature trends are broadly consistent with internal variability. Over most of the early twenty-first century, however, model tropospheric warming is substantially larger than observed; warming rate differences are generally outside the range of trends arising from internal variability. The probability that multi-decadal internal variability fully explains the asymmetry between the late twentieth and early twenty- first century results is low (between zero and about 9%). It is also unlikely that this asymmetry is due to the combined effects of internal variability and a model error in climate sensitivity. We conclude that model overestimation of tropospheric warming in the early twenty-first century is partly due to systematic deficiencies in some of the post-2000 external forcings used in the model simulations.
Zeke has a good summary of the paper at CarbonBrief.
The paper confirms what John Christy has been saying for the last decade, and also supports the ‘denier’ statements made by Ted Cruz about the hiatus. The conclusion that The probability that multi-decadal internal variability fully explains the asymmetry between the late twentieth and early twenty- first century results is low (between zero and about 9%) hinges on results from climate models that are not fit for such a task.
The bottom line is that there are 4 possibilities to explain the 21st century discrepancy between climate models and observations:
- Errors in external forcing data (Santer et al’s preferred explanation)
- Internal variability (which has been supported by numerous previous studies, including posts at CE)
- Values of CO2 climate sensitivity that are too high (interesting new post on this over at ClimateAudit)
- Missing physical processes in the climate models (e.g. solar indirect effects).
In my assessment, all 4 are in play; for the 21st century hiatus, my assessment is that #2 is the dominant factor (with supporting contributions from #3). The Santer et al. paper attempts to address #1 and #2 (unconvincing with respect to #2). But there is much that is unknown and uncertain here, with plenty of scope for rational disagreement on this topic.
Bottom line is that this new Santer et al. paper sort of makes a joke of the Santer, Emanuel and Oreskes op-ed.
Seitter’s statement about skepticism deserves comment:
“Skepticism that fails to account for evidence is no virtue.”
The disagreement is not so much about observational evidence, but rather about the epistemic status of climate models, the logics used to link the observational evidence into arguments, the overall framing of the problem and overconfident conclusions in the face of incomplete evidence and understanding. The ‘multiple lines of evidence’ argument simply doesn’t work for a very complex problem, and there are multiple lines of evidence that lead to alternative conclusions. See my paper Reasoning about climate uncertainty.
Why do scientists disagree about climate change?
- Insufficient and inadequate observational evidence
- Disagreement about the value of different classes of evidence (e.g. global climate models)
- Disagreement about the appropriate logical framework for linking and assessing the evidence
- Assessments of areas of ambiguity & ignorance
- Belief polarization as a result of politicization of the science
An interesting perspective on knowledge about complex systems is this recent aeon article The tree of knowledge is not an apple or an oak but a banyan.
This perspective seems very apt to understanding complex systems. The article provoked this tweet from Silvio Funtowicz:
Alternative definition of complexity: plurality of legitimate perspectives irreducible to a single perspective