At Boston College’s graduation ceremony last spring, former Secretary of State John Kerry warned students with a commonly used, and highly misleading statistic regarding the “crippling consequences of climate change.”

“97 percent of the world’s scientists, continued Kerry, tell us this is urgent.”

But few people understand where this 97 percent meme comes from, nor do they understand its statistical basis.

Many green advocates mistakenly interpret this stat as saying that 97 percent of ALL scientists agree that humans are the primary and main contributing factor to climate change and global warming.

Before debunking the myth of the 97 percent number, it’s important to establish what the alleged majority of scientists are actually agreeing to.

More precise and reasonable language can be found on NASA’s website which says that, “Ninety-seven percent of climate scientists agree that climate-warming trends over the past century are very likely due to human activities.”

The phrase “very likely” takes a little kick out of the absolute certainty that proponents of the 97 percent statistic tend to use, but it’s not near far enough to discredit the number by any means. The circumstance under which that number was derived does a good enough job of that by itself. It certainly narrows down Secretary Kerry’s 97 percent of the entire “world’s scientists” back into the more manageable category of just “climate change scientists” by NASA.

The first claim of 97 percent of climate scientists agreeing on man-made climate change came from a 2009 article in “Eos Transactions American Geophysical Union” by Maggie Kendall Zimmerman who was a student at the University of Illinois.

While there were 3,146 respondents to the survey, Zimmerman intentionally only derived her 97 percent statistic based on the 79 responders who listed their expertise as climate change.

This is not the vast consensus that the public has been led to believe.  

She discarded the opinions of published solar and space scientists, physicists, meteorologists, cosmologists, astronomers and other scientists who could have insight into aspects of climate change, solely because they did not list themselves as climate change experts.

What’s just as important to mention is that Zimmerman’s survey questions did not inquire at all whether or not the climate change scientists thought that human contribution to global warming was significant enough to be a problem in the first place. Had Zimmerman actually presented the opinions of those in related fields, she may not have liked the results.

Repeated surveys of meteorologists continually find that the majority opposes the alleged consensus. A 2012 survey of 1,854 American Meteorological Society members found that 60 percent said that man-made global warming was not dangerous.

But we all know that all meteorologists are just a bunch of good ol’ boy Republicans.

(1) comment

Art Hobson

Although Opinion Editor David Wilson tries valiantly to dismiss the claim that 97.3 percent of climate scientists agree that climate change is human-made (Traveler Oct 28), his attempt fails because he distorts the results of the poll that made this claim. Regarding that 2009 poll published by M. K. Zimmerman, Wilson states "While there were 3,146 respondents to the survey, Zimmerman intentionally only derived her 97 percent statistic based on the the 79 responders who listed their expertise as climate change. This is not the vast consensus that the public has been led to believe." But if you read the actual Zimmerman article, "Examining the scientific consensus on climate change," you'll find that the poll results are far more extensive than Wilson claims. Essentially all geosciences faculty in the country were polled, along with researchers at state geologic surveys and U.S. federal research facilities, 10,257 geoscientists in all. Of these, 3,146 responded--a typical response for web-based surveys. 82% of these agreed that global warming is caused by humans--an overwhelming majority. Zimmerman then looked at more specialized categories of geologists. Among those geologists whose main field is "climatology", 88% agreed with human causation. Among geologists who actively publish research in their field, 88% agree. Among geologists who actively publish research in climate change, 90 percent agree. Finally, among climatologists who actively publish on climate change, 97.3 percent agree. So, among 3,146 respondents, 80% agree with human causation, and when you look at the most highly specialized among them, 97.3 percent agree. Contrary to Wilson's claim, both figures, as well as the poll's other results, represent a vast and impressive consensus. We'd better listen to these scientists.
Art Hobson
Emeritus Professor of Physics
University of Arkansas

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