Where did the '97 Percent' Claim Come From?

John Robson, the Canadian historian and journalist who runs the Climate Discussion Nexus, has put out an updated version of CDN's most popular video. The video, which has more than 1 million views on YouTube, debunks the dishonest claim that, in the words of Barack Obama, "Ninety-seven percent of scientists agree: climate change is real, man-made, and dangerous." Virtually none of that statement is accurate, but it continues to be parroted by the Thunbergian activist class, and by journalists of all stripes, even those who should know better. Here's an excerpt, which examines the sleight of hand at the heart of the "97 percent" claim:

In 2009, a pair of researchers at the University of Illinois sent an online survey to over 10,000 Earth scientists asking two simple questions: Do you agree that global temperatures have generally risen since the pre-1800s? and Do you think that human activity is a significant contributing factor? They asked some other questions too, but didn’t report the questions or results in the publication. They didn’t single out greenhouse gases, they didn’t explain what the term “significant” meant, and they didn't refer to danger or crisis.

So what was the result? Of the 3,146 responses they received, 90 percent said yes to the first question, that global temperatures had risen since the Little Ice Age, and only 82 percent said yes to the second, that human activity was a significant contributing factor. Interestingly, among meteorologists only 64 percent said yes to the second, meaning a third of the experts in the study of weather patterns who replied didn’t think humans play a significant role in global warming, let alone a dominant one. What got the most media attention was that among the 77 respondents who described themselves as climate experts, 75 said yes to the second question. 75 out of 77 is 97 percent.

OK, it didn’t get any media attention that they took 77 out of 3,146 responses. But that’s the key statistical trick. They found a 97 percent consensus among 2 percent of the survey respondents. And even so it was only that there’d been some warming since the 1800s, which virtually nobody denies, and that humans are partly responsible. These experts didn’t say it was dangerous or urgent, because they weren’t asked.

Furthermore:

Another survey appeared in 2013, by Australian researcher John Cook and his coauthors, in which they claimed to have examined about 12,000 scientific papers related to climate change, and found that 97 percent endorsed the consensus view that greenhouse gases were at least partly responsible for global warming. This study generated headlines around the world, and it was the one to which Obama’s tweet was referring. But here again, appearances were deceiving.

Two-thirds of the papers that Cook and his colleagues examined expressed no view at all on the consensus. Of the remaining 34 percent, the authors claimed that 33 percent endorsed the consensus. Divide 33 by 34 and you get 97 percent. But this result is essentially meaningless, because they set the bar so low. The survey authors didn’t ask if climate change was dangerous or “manmade.” They only asked if a given paper accepted that humans have some effect on the climate, which as already noted is uncontroversial....

So a far better question would be: How many of the studies claimed that humans have caused most of the observed global warming? And oddly, we do know. Because buried in the authors’ data was the answer: A mere 64 out of nearly 12,000 papers! That’s not 97 percent, it’s one half of one percent. It’s one in 200.

Be sure to watch the whole thing and share it with your non-insane friends: