PNAS Climate Change Expert Credibility Farce

A new, purportedly scientific report in the Proceedings of the National Academy of Sciences (PNAS) is claiming that more “top” environmental scientists believe in global warming. Moreover, the report also claims that the scientists who do believe in global warming—now re-labeled anthropogenic climate change (ACC)—have higher credibility than those who do not. All of this is based on an “extensive dataset of 1,372 climate researchers and their publication and citation data.” Citing such data is like saying “most of the people who write for conservative magazines are conservatives.” In other words, the study is devoid of factual significance and possibly purposely misleading. More propaganda from the sinking global warming ship.

In an open access article, rather innocuously titled “Expert credibility in climate change,” William R. L. Anderegg, James W. Prall, Jacob Harold, and Stephen H. Schneider have attempted to denigrate those who dare to disagree with the IPCC party line. In order to provide a false sense of balance, the “researchers” refer to climate change believers as “convinced by the evidence” (CE) and skeptics as “unconvinced by the evidence” (UE). That is the only unbiased thing about the report. Here is the paper's abstract:

Although preliminary estimates from published literature and expert surveys suggest striking agreement among climate scientists on the tenets of anthropogenic climate change (ACC), the American public expresses substantial doubt about both the anthropogenic cause and the level of scientific agreement underpinning ACC. A broad analysis of the climate scientist community itself, the distribution of credibility of dissenting researchers relative to agreeing researchers, and the level of agreement among top climate experts has not been conducted and would inform future ACC discussions. Here, we use an extensive dataset of 1,372 climate researchers and their publication and citation data to show that 97–98% of the climate researchers most actively publishing in the field support the tenets of ACC outlined by the Intergovernmental Panel on Climate Change, and the relative climate expertise and scientific prominence of the researchers unconvinced of ACC are substantially below that of the convinced researchers.

The first suspicious thing is that the “extensive dataset” contains only 1,372 climate researchers on both sides of the issue. I seem to recall that the IPCC alone claimed more than that many “experts” had worked on its reports. The second suspicious thing is the 97-98% pro-AGW result, a figure more in line with the election results from a tin-pot dictatorship or Stalinist people's republic. This result alone is an indication that the dataset is biased. Here is how the authors described their methodology:

We ranked researchers based on the total number of climate publications authored. Though our compiled researcher list is not comprehensive nor designed to be representative of the entire climate science community, we have drawn researchers from the most high-profile reports and public statements about ACC. Therefore, we have likely compiled the strongest and most credentialed researchers in CE and UE groups. Citation and publication analyses must be treated with caution in inferring scientific credibility, but we suggest that our methods and our expertise and prominence criteria provide conservative, robust, and relevant indicators of relative credibility of CE and UE groups of climate researchers.

They clearly state that they selected researchers from the “most high-profile reports and public statements,” obviously a judgment call on the author's part—and there is no doubt which side of the debate the authors are on. The statement that they have compiled the “strongest and most credentialed researchers in CE and UE groups” is shear supposition on the author's part. They rightly hint that counting citations and publications is not a reliable indication of scientific credibility. Since the whole point of the article is to make the claim that climate change believers are more credible than non-believers, this amounts to an admission that the whole report is based on a faulty assumption. Then, after warning that their list is not comprehensive, nor designed to be representative, and that publication analyses must be treated with caution, they blithely state that their methods are sound. What hogwash.

After this claim that their biased, subjective data and laughable methodology should nonetheless be accepted as credible, the author's present a number of dubious assertions. The plot below, figure 2 from the article, is typical of these “analyses” of the data. It show the distribution of the number of the top 50 most-published researchers from CE and UE categories with a given number of total climate publications. Tick marks indicate the center of righ-inclusive categories (e.g.,20–50, 51–100, 101–150, etc.).

The assertion that the quality of a scientist's work, and by extension the scientific credibility of that scientist, can be discerned by the shear volume of his publications is ludicrous. Having an academic background myself, I can tell you that there are some scientists who turn out a staggering number of papers—they seem to thrive on writing and publishing. This is fine, and since many academic institutions place exaggerated value on the number of publications a scholar has, there is a trend toward this type of activity. Everyone in academia has heard the old saw, “publish or perish.”

If you habitually read climate related literature, as I do, you will find the same authors, in various combinations, publishing papers that are slightly different versions of each other. Another factor to consider is that scientists who are also university professors often publish papers done by students under their charge. This also contributes to publication bloat. Simply put, having a large number of publications does not mean that a scholar has anything noteworthy to say. Indeed, many great scientists published only a few seminal papers.

Further evidence that this study draws on sources that guaranty a uniformity of opinion is given in the paper's supplementary information. As you can see by looking at the data sources, it is unsurprising that they would find their sample researchers to be in agreement with the IPCC—that is were they started!

We compiled these CE researchers comprehensively (i.e., all names listed) from the following lists: IPCC AR4 Working Group I Contributors (coordinating lead authors, lead authors, and contributing authors; 619 names listed), 2007 Bali Declaration (212 signers listed), Canadian Meteorological and Oceanographic Society (CMOS) 2006 statement (120 names listed), CMOS 2008 statement (130 names listed), and 37 signers of open letter protesting The Great Global Warming Swindle film errors. After removing duplicate names across these lists, we had a total of 903 names.

For UE researchers they relied on 12 lists, ranging from the Science and Environmental 1995 Leipzig Declaration (80 names), to the 2009 newspaper ad by the Cato Institute challenging President Obama’s stance on climate change (115 signers), for a total of 472 names. The fair-minded reader might wish to consider the difference in sources between the two groups and whether the skeptics would be likely to submit their work to the same journals as the CE researchers. After all, openly skeptical articles on climate change would have a hard time passing peer review when the reviewers are all AGW believers.

Another complication is that many of the skeptics are from related fields and do not consider themselves as climate scientists first. My doctorate is in computer science and I have published a number of papers on computer modeling of complex systems, work that directly applies to analyzing the complex GCM used to predict climate change. I doubt that this paper's authors would count my publications in computer science or my earlier publications in protein science, just those in acceptable climate science journals.

What's more, the sources used for this paper—the most cited authorities pro and con—were supplied by one of the paper's authors, Jim Prall (picture on left). Prall, a self-described non-academic, runs a climate change website of his own. As it turns out, Prall has been collecting a list of people he disagrees with for some time now. Roger Pielke Jr., has described it as a “black list” for climate skeptics. Prall's list of the most cited skeptical authors on climate science can be found here.

I see little need to expound on the type of people who keep enemies lists but, by his own admission, Prall is fed up with “the tiny minority of 'climate skeptics' or 'deniers' who try to minimize the problem, absolve humans of any major impact, or suggest there is no need to take any action.” Oh yes, Jim is certainly a disinterested, open-minded observer who's data should be used to evaluate the expertise of climate change skeptics. This is the equivalent of stuffing a ballot box—the whole selection process used in this paper is wrong on so many levels it beggars the imagination.

If I seem more than a bit incensed by the publication of this piece of twaddle, it is because I am personally involved. I am proud to tell my readers that I am listed as #387 on the skeptics black list. That is only four places behind my friend Joe D'Aleo and three places ahead of Lord Monckton (sorry Sir Christopher). I am sad to say that my colleague and co-author, Allen Simmons, is farther down the list at 457, but that is far from last and just being on the list is a badge of honor for a skeptic. Climate Depot's Marc Morano is not on the list, probably because Marc does not claim to be a scientist, but is mentioned as a source of names. The list amounts to a veritable who's who of climate change skeptics, an honnor roll of those who have worked so hard to debunk the AGW hoax. Sorry Jim, your half-assed attempt at character assassination seems to have backfired.

The PNAS paper is a meaningless propaganda piece, pure and simple. The “research” presented was designed to produce a biased answer. If students of mine submitted similar work they would receive a failing grade. It is so biased in its data collection and analyses that it is incapable of proving anything. As Wolfgang Pauli said, “This isn't right, it isn't even wrong.”

The fact that this pile of intellectual excrement is being published in PNAS shows how pervasive the climate change clique's influence is and the depth of hypocrisy in the climate science community. This paper's publication is an indication of how frightened the climate change alarmists have become. They obviously now feel that they must discredit any scientist who dares to speak against the IPCC dogma.

Be safe, enjoy the interglacial and stay skeptical.

Hell no! I'm proud to be #387 on the black list.

Greens disgust me

Y'know, if you really want to get to the abysmal self-hatred and overall deep misanthropy behind the whole Green movement, you only have to look at the spate of different articles that refer to humans as "parasites" and openly support massive genocidal events as A Real Good Thing.

Greens disgust me.

Start with reading more carefully

The sample was for two different groups: one assumed to be biased in favor of global warming, the other against. This was not an unbiased poll but rather a confirmation of what each group thinks — confidence intervals and sample sizes are irrelevant. As I stated, the “researchers” selected the people who's work was sampled. And since it was the number of papers counted, not the researchers themselves, authors who generate a large volume of similar publications would also bias the result. As I said, this survey is meaningless — just like your objections.

PS: Thanks for finding the typo, at least that was useful.

Peer Review is notably flawed when incestuous

"After all, openly skeptical articles on climate change would have a hard time passing pear [sic] review when the reviewers are all AGW believers."

Ahahaha yes, it sure is hard to pass my brilliant theory when all those mean scientists use science to disprove it.

Peer review doesn't mean they use "science" to disprove it. That would require that they actually reproduce the experiments and find them to be repeated in their own experience. Given that AGW (sorry, I refuse to ignore the attempt at fast footwork by changing terminology to match a blatant mismatch to the facts) "scientists" are notably resistant to anyone actually knowing their methodology to the extent where it's repeatable (either or both by refusing access to the data sets or to the formulas, etc., used to produce them -- or statistics based on them -- from raw data) specifically REJECTS the idea that it's "science".

In real fact, MOST of the "soft sciences" have gotten AWAY from doing enough to reproduce the findings, and it has led, in many cases, to a regular backtracking on a wide array of "soft science" conclusions.

There are now numerous reports regarding "findings" that were taken quite seriously and believed completely valid which are being found, when applied to the Real World, to be blatantly specious and questionable:
The Decline Effect

This is hardly a single article:
Is Psychology About to Come Undone?

It's about FAD SCIENCE -- the soft science tendency to follow what are defacto no different from FADs -- an idea becomes popular, and suddenly a whole host of "peer reviewed" articles pop up which support that idea. A decade passes, and people start to find that subsequent results don't match the data, and this makes people go back and look at the original studies and find they don't work any more either.

What happened was that the peer review process lost all rigor sometime in the last four-to-five decades in a lot of arenas.

AGW is no different from these soft, "FAD" sciences -- markedly subject to financial, political, and sociological distortions -- to the extent where its conclusions are constantly requiring various revisions, corrections, and "Gee, we screwed up. Sorry about that thirty million we made you waste!"

Mowrey's Law (pp1):
"Funded research tends to drive out unfunded research in the marketplace of ideas."

If most of your funding goes to people who want to prove AGW, and none goes to people who want to disprove AGW -- The result is NOT SCIENCE.

The "science" of AGW needs its own Reproducibility Project. 'Cause it's crap, and anyone who pays close attention to its remarkably poor record of predictions knows it.

The Schwartzberg Test (#504):
"The validity of a science is its ability to predict."

On that, we know Climate Science is of about 10% validity.

The only unbiased thing?

"... the “researchers” refer to climate change believers as “convinced by the evidence” (CE) and skeptics as “unconvinced by the evidence” (UE). That is the only unbiased thing about the report."

I dunno. The CE and UE terms presuppose that some actual evidence for CAGW exists, but after the exhausting and uniquely unedifying effort of crawling through AR4 WG1, I have been unable to find any. So I might quibble with your characterization of these terms as "unbiased."

Craig Goodrich

Convinced by the evidence

I think saying that sceptics are unconvinced by the evidence is outright wrong. The sceptics, myself included, are indeed convinced by the evidence, that AGW is unproven and that other causes of the slight warming since the LIA exist.
If any substantive evidence for AGW existed, I would be convinced. Considering the time, effort, research and resources devoted to the single minded effort of proving AGW, the complete lack of empirical evidence speaks volumes.
I am indeed convinced by the evidence. It is the AGW supporters who remain unconvinced.


Perhaps I was being too charitable, but at least they did not use the term “denier.”

Oliver Crangle

It bothers me that I am the only person to recall, in this context, the list of Oliver Crangle.

Four O'Clock

For those not up on old Twilight Zone episodes, Oliver Crangle was the central character in a story titled "Four O'Clock". Crangle was a fanatic who maintained records of people he deemed evil, and who eventually decided to eliminate all evil from the world. His plan was to shrinking the "evil" people to two feet tall. Being The Twilight Zone, things did not go as Oliver planned, much as things have not gone well for the PNAS paper authors. For more, follow the link below:

Climate Change Supporters Attack PNAS Report

The PNAS hatchet job article has provoked a firestorm of criticism from skeptics and now it appears that climate change adherents are attacking the paper as well. Spencer Weart, a trained physicist and historian specializing in the history of modern physics and geophysics, is a well known climate change supporter. He has posted the following comment on the warmist leaning, Skeptical Science website:

Although I am personally "convinced by the evidence" and am surprised at the number who are not, I have to admit that this paper should not have been published in the present form. I haven't read any other posts on this; the defects are obvious on a quick reading of the paper itself. Here's what I saw: Many scientists might have been "unconvinced by the evidence" and yet chosen not to volunteer to sign a politicized statement that "strongly dissented" from the IPCC's conclusions -- which is the only criterion the authors of the paper had. What if they weakly dissented or are just, like many scientists, shy about taking a public stand? You don't have to invoke groupthink, fear of retribution or all that.

With the integrity of their paper being assailed from both sides of the climate change debate, the only respectable thing for Anderegg et al. to is withdraw the paper.

What about number of pages?

Since it's not content that determines scientific credibility, I think the number of pages in a paper should be considered. A 10 page paper wouldn't carry the same weight as a 15 or 20 page paper; otherwise the author(s) of the shorter paper gets an unfair advantage over the longer paper. Just add up the total number of pages and whoever has the most pages is the most credible. Time for a simple system that will end all the bickering over data, methods and interpretation.

P.S I hate CAPTCHA because it is often hard to make out what the letters are.

Page counts

Many journals have a page count limit, which would skew any use of total page count as a metric. And as I said in my post, volume doesn't indicate the value of the content. Claude Shannon is famous for having founded information theory with one landmark paper published in 1948. That paper was his Master's thesis and was only 28 pages long, not counting the appendices, which nowadays would be relegated to “supporting material” in a journal article. Counting papers, pages or citations will not get you a meaningful sense of a scientist's level of expertise or eventual importance to science.

As for the Captcha, it is a necessary evil. Join the site and stay logged in, I do.

Comments welcome

Welcome aboard and please feel free to comment all you would like. It is only by asking questions or posing alternative solutions that science advances. The only inane behavior is refusing to give up one's cherished notions in the face of contradictory evidence :-)

The Global Warming Inquisition Has Begun

Dr. Roy Spencer has an essay regarding the PNAS article and the black list flap over on

Not surprisingly, the study finds that the skeptical scientists have fewer publications or are less credentialed than the marching army of scientists who have been paid hundreds of millions of dollars over the last 20 years to find every potential connection between fossil fuel use and changes in nature.

After all, nature does not cause change by itself, you know.

The study lends a pseudo-scientific air of respectability to what amounts to a black list of the minority of scientists who do not accept the premise that global warming is mostly the result of you driving your SUV and using incandescent light bulbs.

Good stuff.

Known by your enemies

They say you are known by your enemies, which means you must be a pretty fine fellow, Dr. Hoffman.