1.6%, Not 97%, Agree that Humans are the Main Cause of Global Warming
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1.6%, Not 97%, Agree that Humans are the Main Cause of Global Warming

From an article by David Henderson in the website The Library of Economics and Liberty

Mark Bahner, a commenter on my previous post on global warming and on David Friedman’s post, has sifted through the data behind John Cook’s statement that 97% of climate scientists who stated a position believe that humans are the main cause of global warming. Recall that Bedford and Cook lumped together those who believe that humans are the main cause with those who believe that humans are a cause. Cook et al did not report the percent of abstracts in which the scientists said that humans are the main cause of global warming. But Bedford and Cook (the same Cook), citing Cook et al, misrepresented the results of Cook et al.

Unfortunately, neither Cook et al nor Bedford and Cook reported, even though they had a category for, the percent of abstracts that claimed that humans are the main cause of global warming. Fortunately, Mark Bahner, an enterprising commenter on both David Friedman’s and my posts, managed to find their data and went through and did his own calculation. He reported his results in a comment on my previous post but, because the post was two days ago, it’s worth pointing out in a separate post. Thus this one.

According to Bahner (and I have not gone through and checked the raw data for myself), of the 11,944 abstracts that Cook et al examined, only 64 claimed explicitly that humans are the main cause of global warming.

Here are the categories that Cook et al state. I have added the numbers that Bahner found beside each.

1,Explicitly endorses and quantifies AGW as 50+% : 64
2,Explicitly endorses but does not quantify or minimize: 922
3,Implicitly endorses AGW without minimizing it: 2910
4,No Position: 7970
5,Implicitly minimizes/rejects AGW: 54
6,Explicitly minimizes/rejects AGW but does not quantify: 15
7,Explicitly minimizes/rejects AGW as less than 50%: 9

So 64 out of 11,944, or 0.5%, take the view that humans are the main cause of global warming. But that includes all abstracts, including those that did not take a position. It would be nice to take the 64 as a percent of those that did take a position. Unfortunately, in their data set, Cook et al put 4a, those that do not address the cause of global warming, with 4b, those that express the view that humans’ role in global warming is uncertain or undefined. It would be nice to separate them, but we can’t unless we have the even rawer data. So let’s generously conclude that everyone in category 4 has expressed no view. That’s a total of 7970, leaving a total of 3,974 that have expressed a view. The 64 who think the main cause is humans is, drum roll please: 1.6%.

1.6% is pretty different from 97%.

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