The 97 Percent Myth

Global warming advocates routinely toss out the statistic that 97 percent of scientists agree that climate change is real and man-made. Where did that figure come from? Joseph Bast, president of the Heartland Institute, and Roy Spencer, principal research scientist for the University of Alabama in Huntsville, explain the history behind the misleading number, in The Wall Street Journal.

In short, there is no basis for the claim that 97 percent of scientists believe that man-made climate change is a dangerous problem.

In 2004, Naomi Oreskes, a Harvard science historian, examined 928 abstracts of scientific journal articles, finding that three-quarters of them believed that humans were responsible for most of the observed warming of the last half-century.

• However, Oreskes did not analyze articles by prominent scientists — such as Richard Lindzen and John Christy — who question the “consensus” view.
• Additionally, a recent study in Nature magazine confirms that academic abstracts often contain claims that are not proven in the studies themselves.

A 2009 article by University of Illinois student Maggie Kendall Zimmerman and her master’s thesis adviser Peter Doran also made the 97 percent claim.

• The authors made this conclusion after conducting a two-question online survey of 3,146 scientists, only 79 of which were experts in climate science and had published half of their recent peer-reviewed papers on climate change.
• It did not include the scientists most likely to understand the natural causes of climate change: solar scientists, space scientists, cosmologists, physicists, meteorologists or astronomers.
• Moreover, the survey did not specify whether the human impact on global warming was large enough to constitute a problem.

In 2013, Australian blogger John Cook reviewed abstracts of peer-reviewed papers published from 1991 to 2011, concluding that 97 percent of the authors who stated their position on the subject believed that human activity was responsible for some warming.

• However, when University of Delaware geography professor David Legates reviewed Cook’s papers, he found that only 41 of them (0.3 percent of all of the abstracts, and just 1 percent of those that expressed an opinion) believed human activity was causing most current warming.

On the other hand, write Bast and Spencer, the Petition Project — a group of physicists and physical chemists in California — has collected more than 31,000 signatures from scientists agreeing that there is “no convincing scientific evidence that human release of…carbon dioxide…or other greenhouse gases is causing or will, in the foreseeable future, cause catastrophic heating of the Earth’s atmosphere and disruption of the Earth’s climate.”

More From NCPA: