Christopher Moore is an Assistant Professor of Physics at Coastal Carolina University. He lives in Myrtle Beach, SC with his wife and two children.Pundits on television have been throwing around the number 97% recently. Specifically, they are claiming that 97% of active climate scientists agree that the earth has warmed since the beginning of the industrial period and that human action is chiefly responsible. Where in the world does this number come from?
I was prompted to ask, because such agreement among scientists in a model driven (and therefore, assumption driven) field is pretty unusual. Also, this has been the argument every discussion of global warming comes to when liberal pundits appear on conservative shows. Let’s leave aside the obvious appeal to authority, since, well global climate is a pretty intricate business and we shouldn’t expect every Fox News viewer to be an expert. Also, forget about the political implications and/or prescriptions. Do 97% of active climate scientists actually agree on something, or was this number made up?
The answer to the first question is yes. The number is 97%, and this number is a pretty good estimate. Why might you think otherwise?
Within the last few days, Lawrence Solomon wondered out loud about this 97% number. So did Wendy McElroy. Both somehow came to the conclusion that the number 97 was rolling off pundi-tongues due to a self-selecting online survey. Apparently, this number came from a non-peer reviewed article describing an online poll in which 79 climate scientists participated.
The original story came from the Hockey Schtick blog, where they pointed to this article by Peter Doran and Maggie Zimmerman. There are obvious flaws in this study, as these bloggers have pointed out.
The problem these folks have is that every article I have ever read that has actually referenced the 97% figure points to a study published in the Proceedings of the Natural Academy of Sciences. In this article, they use a dataset of over 1,300 climate scientists who are active in the field as measured by publication rate and citations. That number seems about right, since I would doubt there would be many more people doing serious, hard-core research in this field. Anyway, they are the original source of the 97% number, the article is peer-reviewed, and we’re not talking about some cheesy online poll.
Score one for the conservative blog-o-sphere.
Now, it could be claimed that active “climate scientists” are an obvious self-selecting group. Maybe they all have a political agenda and are involved in a massive (actually, quite small) conspiracy. I doubt that, but at least that’s a better argument against the “97% agree” figure.
Unfortunately, as much as my political sensibilities urge me not to, I must agree with Jonathan Kay that global warming deniers are a liability to the conservative cause.
Now, if only those on the left would stop conflating nearly unanimous agreement that global warming is real and anthropogenic with dire predictions of world-ending chaos, then we could have a good debate.
Aside: I was prompted to investigate this number from a segment on Hannity guest hosted by Tucker Carlson. I’m guessing he’s playing to the crowd that watches the show, but I don’t remember him being someone that played to the Global Warming Denier crowd in the past. The Global Warming articles on his website The Daily Caller have been more accurate, though with a flair for the dramatic headline that I can appreciate.