On Tuesday, the Competitive Enterprise Institute (CEI) sent NASA a formal complaint, asking the agency to withdraw the false claim that 97 percent of climate scientists agree that humans are the primary cause of global warming and climate change. The 2013 study purporting to demonstrate that number was fatally flawed and proved no such thing.
“The claim that 97% of climate scientists believe humans are the primary cause of global warming is simply false,” CEI attorney Devin Watkins said in a statement. “That figure was created only by ignoring many climate scientists’ views, including those of undecided scientists. It is time that NASA correct the record and present unbiased figures to the public.”
According to the CEI complaint, NASA’s decision to repeat the false claim violated the Information Quality Act (IQA). Specifically, NASA claimed that “[n]inety-seven percent of climate scientists agree that climate-warming trends over the past century are extremely likely due to human activities.” The claim appears on the NASA website on the page “Climate Change: How Do We Know?”
The claim traces back to a study led by John Cook entitled “Quantifying the consensus on anthropogenic global warming in the scientific literature” and published in the journal Environmental Research Letters in 2013.
The study is fundamentally dishonest, as the CEI complaint explains. The study analyzed all published peer-reviewed academic research papers from 1991 to 2011 that use the terms “global warming” or “global climate change.” The study placed the papers into seven categories: explicit endorsement with quantification, saying humans are responsible for 50+ percent of climate change; explicit endorsement without quantification; implicit endorsement; no position or uncertain; implicit rejection; explicit rejection with qualification; and explicit rejection without qualification.
The study found: 64 papers had explicitly endorsed anthropogenic global warming (AGW) with quantification (attributing at least half of climate change to humans); 922 papers had explicitly endorsed AGW without quantifying how much humans contribute; 2,910 papers had implicitly endorsed AGW; 7,930 papers did not state a position and 40 papers were uncertain; 54 papers implicitly rejected AGW by affirming the possibility that natural causes explain climate change; 15 papers explicitly rejected AGW without qualification; and 9 papers explicitly rejected AGW with quantification, saying human contributions to global warming are negligible.
So how did Cook and his team come up with the 97 percent number? They added up the first three categories (3,896 papers), compared them to the last three categories (78 papers) and the papers expressing uncertainty (40 papers), and completely ignored the nearly 8,000 papers that did not state a position.
Of the papers Cook’s team characterized as stating a position, 97 percent (3,896 of the 4,014 papers) favored the idea of man-made global warming.
See the problem? The study completely discounted the majority of the papers it analyzed (66.4 percent — 7,930 of the 11,944 papers analyzed). With those papers included, only 32.6 percent of the papers explicitly or implicitly endorsed AGW (3,896 of 11,944 papers).
But it gets worse. Many of the scientists who wrote the original papers Cooks’ team analyzed complained that this study mischaracterized their research.
The survey “included 10 of my 122 eligible papers. 5/10 were rated incorrectly. 4/5 were rated as endorse rather than neutral,” complained Dr. Richard Tol, professor of the economics of climate change at Vrije Universiteit.
Cook survey included 10 of my 122 eligible papers. 5/10 were rated incorrectly. 4/5 were rated as endorse rather than neutral.
— Richard Tol (@RichardTol) May 22, 2013
He argued that of the 112 omitted papers, only 1 strongly endorses man-made global warming.
“That is not an accurate representation of my paper,” wrote geography Ph.D. Craig Idso. “Nope … it is not an accurate representation,” Nir Shaviv, associate professor at the Hebrew University of Jerusalem, wrote.
Ph.D. physicist Nicola Scafetta complained that “Cook et al. (2013) is based on a strawman argument because it does not correctly define the IPCC AAGW theory, which is NOT that human emissions have contributed 50%+ of the global warming since 1900 but that almost 90-100% of the observed global warming was induced by human emission.”
Cook’s team categorized his paper as one that “explicitly endorses and quantifies AGW as 50+%.” Scafetta countered, “What my papers say is that the IPCC view is erroneous because about 40-70% of the global warming observed from 1900 to 2000 was induced by the sun.”
Even including Scafetta’s incorrectly categorized study, Cook’s team only found 64 papers that explicitly endorsed man-made global warming and attributed more than 50 percent of it to human activity. That represents a minuscule 0.5 percent of the 11,944 papers. Even excluding the 66.4 percent of the papers that did not take a position, the 50 percent plus approach only accounts for 1.6 percent of all papers in the Cook study.
The study — and the 97 percent figure that depends on it — is fatally flawed, and NASA has 120 days to respond to the CEI complaint. It is far past time people reject this false claim.
Follow Tyler O’Neil, the author of this article, on Twitter at @Tyler2ONeil.