In May 2013 John Cook et al published a paper in Environmental Research Letters, published by IOP publications. The paper was titled “Quantifying the consensus on anthropogenic global warming in the scientific literature”. In it they claim that they find a 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature.” The project was conceived as a ‘citizen science’ endeavor using volunteers from the Skeptical Science website.
Except they didn’t. The previous statement was published on the website of Skeptical Science, a weblog that Cook and one of his co-authors, Dana Nuccitelli, operate. (Although there is a lot of science on the website, to call it skeptical is not accurate. It is a purveyor of consensus messages, pure and simple.) But what their paper actually says is very different: “We analyze the evolution of the scientific consensus on anthropogenic global warming (AGW) in the peer-reviewed scientific literature, examining 11,944 climate abstracts from 1991–2011 matching the topics ‘global climate change’ or ‘global warming’. We find that 66.4% of abstracts expressed no position on AGW, 32.6% endorsed AGW, 0.7% rejected AGW and 0.3% were uncertain about the cause of global warming. There is a dramatic difference between “97% Consensus on Human-Caused Global Warming” and “66.4% of abstracts expressed no opinion on AGW.”
“The ‘97% consensus’ article is poorly conceived, poorly designed and poorly executed. It obscures the complexities of the climate issue and it is a sign of the desperately poor level of public and policy debate in this country [UK] that the energy minister should cite it.”
Like Oreskes and Anderegg, Prall et al, Quantifying the Consensus (which I will shorten to QTC going forward) consists of a literature review of published science to (in my opinion) justify their belief that the consensus view of climate warming was overwhelming. Once again for the record, I believe the majority of scientists do believe in a fairly narrow version of the consensus position–as I remarked in a previous post, two reputable surveys put the percentage of climate scientists who agree with the consensus at about 81%. But, as with Oreskes and as with Anderegg, Prall et al, 81% is not enough for Cook and his associates. So let’s see what games they have to play to get to their heralded 97%.
They clarify quickly–“Among abstracts expressing a position on AGW, 97.1% endorsed the consensus position that humans are causing global warming. In a second phase of this study, we invited authors to rate their own papers.” So, okay–out of 11,944 abstracts of papers on climate change, 3,894 endorsed the consensus position in the abstract. For some reason that doesn’t sound as dramatic… but it’s still data. Isn’t it? Well, the fact that QTC cited Oreskes three times, Stephan Lewandowsky and Anderegg, Prall et al should serve as a bit of a warning..
We saw with Oreskes and Anderegg, Prall et al that they gamed the system, stacked the deck to produce results favorable to their political position on the issue. Oreskes did it by using a search term that skeptic scientists were unlikely to use in a title (Global Climate Change), so she could ignore the many publications by skeptical scientists that in fact existed. Anderegg, Prall et al used Google Scholar instead of an academic database, searched only in English and cherry-picked their opponents from signatures to vastly different public letters on environmental issues (they could have, if they chose, labeled Linus Pauling, Jonas Salk and Norman Borlaug as ‘deniers’).
Cook and company did worse on QTC, if that’s possible. Most of their shenanigans have been chronicled at one or more of the skeptic weblogs that follow the climate debate, so they have done most of the heavy lifting for me.
First, their statement is so broad that many skeptics have already stated they agree with it. The globe is warming and humans have caused (some of) it. To be classified as endorsing the consensus position it was enough to say at some point in the abstract that ‘humans are contributing to global warming’. As Cook wrote on Skeptical Science, “We’re basically going with [a definition of] AGW = “humans are causing global warming” Eg [sic] – no specific quantification.” This is very different from what the IPCC says–that humans have caused 90% of global warming. This lower bar renders the conclusion almost meaningless.
Public figures in the climate debate ranging from Roy Spencer to Andrew Montford (Bishop Hill) quickly stepped forward and said they agreed with the statement. I honestly don’t remember reading any skeptic saying otherwise. That’s not what the climate debate is about. (It’s about how much, over what time span and what will it be and what will it do going forward.) So they fail to segment the target populations and cannot therefore differentiate between true consensus holders and skeptics.
During the study that was the basis for QTC, two teams of citizen scientist analysts classified papers using 7 different categories ranging from explicit endorsement to explicit rejection. The Cook et al study data base has seven categories of rated abstracts:
1. 65 explicit endorse, >50% warming caused by man
2. 934 explicit endorse
3. 2,933 implicit endorse
4. 8,261 no position
5. 53 implicit reject
6. 15 explicit reject
7. 10 explicit reject, <50% warming caused by man
The highest level of endorsement–“Endorsement level 1, Explicitly endorses and quantifies AGW as 50+%.(human actions causing 50% or more warming)” was assigned by the raters to a grand total of 65 out of the 12,000 papers evaluated. This certainly is a weak finding. Even combined with level 2’s 934 papers it amounts to less than 10%.
Worse yet, Many papers were not classified correctly. The errors brought to light to date are all in the same direction–papers that were described as endorsing the consensus in fact did not, according to the authors. The Skeptical Science crowd classified papers by prominent skeptics as pro-consensus and the skeptics were happy to point out the mistakes.
It gets worse. “The Cook et al. (2013) 97% paper included a bunch of psychology studies, marketing papers, and surveys of the general public as scientific endorsement of anthropogenic climate change.
“Let’s walk through that sentence again. The Cook et al 97% paper included a bunch of psychology studies, marketing papers, and surveys of the general public as scientific endorsement of anthropogenic climate change. This study was multiply fraudulent and multiply invalid already – e.g their false claim that the raters were blind to the identities of the authors of the papers they were rating, absolutely crucial for a subjective rating study. (They maliciously and gleefully revealed “skeptic” climate science authors to each other in an online forum, as well as other authors. Since they were random people working at home, they could simply google the titles of papers and see the authors, making blindness impossible to enforce or claim to begin with.” We see then that Cook and his crew adopted the same shady tactics as Oreskes and Anderegg, Prall et al to fatten their numbers and obscure the fact that the consensus is narrower and smaller than they want to project to the public.
So why am I dredging up criticisms of QTC at this late stage? We’ll see after I get through with Stephan Lewandowsky. I’ll close this post with a pertinent comment by Dan Kahan of the Yale Law School’s Cultural Cognition Project: “But it is demonstrably the case (I’m talking real-world evidence here) that the regular issuance of these studies, and the steady drum beat of “climate skeptics are ignoring scientific consensus!” that accompany them, have had no—zero, zilch—net effect on professions of public “belief” in human-caused climate change in the U.S.
“On the contrary, there’s good reason to believe that the self-righteous and contemptuous tone with which the “scientific consensus” point is typically advanced (“assault on reason,” “the debate is over” etc.) deepens polarization. That’s because “scientific consensus,” when used as a rhetorical bludgeon, predictably excites reciprocally contemptuous and recriminatory responses by those who are being beaten about the head and neck with it.”