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The Increasingly Elusive Climate Consensus

May 18, 2015 in Economics

By Ross McKitrick

Ross McKitrick

We are often told nearly all climate scientists agree on… something. But on what, exactly, do they agree? In 2013 President Obama sent out a tweetclaiming 97% of climate experts believe global warming is “real, man-made and dangerous.” As it turns out the survey he was referring to didn’t ask that question at all. At a recent debate in New Orleans I heard climate activist Bill McKibben claim there was an expert consensus that greenhouse gases are “a grave danger.” But when challenged for the source of his claim, he promptly withdrew it.

The Intergovernmental Panel on Climate Change asserts the conclusion that most (more than 50%) of the post-1950 global warming is due to human activity, chiefly greenhouse gas emissions and land use change. But they do not survey their own contributors, let alone anyone else, so we do not know how many experts agree with them.

One commonly-cited survey asked if carbon dioxide is a greenhouse gas and human activities contribute to climate change. But these are trivial statements that even many IPCC skeptics agree with. And neither statement speaks to any potential harm done by climate change. So there are no policy implications of such surveys, regardless of the level of agreement.

What we need to call out is the use of false propaganda and demagoguery regarding one of the most complex scientific and policy questions of our time.”

The most highly-cited paper supposedly found 97% of published scientific studies support man-made global warming. But in addition to poor survey methodology, that tabulation is often misrepresented. Most papers (66%) actually took no position, and of the remaining 34%, 33% supported at least a weak human contribution to global warming. So divide 33 by 34 and you get 97%: but this is unremarkable since the 33% includes many papers that critique key elements of the IPCC position.

Two recent surveys shed more light on what atmospheric scientists actually think. Bear in mind that on a topic as complex as climate change, a survey is hardly a reliable guide to scientific truth. But if you want to know how many people agree with your view, a survey is the only way to find out.

In 2012 the American Meteorological Society (AMS) surveyed its 7,000 members, receiving 1,862 responses. Of those, only 52% said they think global warming over the 20th century has happened and is mostly manmade (the IPCC …read more

Source: OP-EDS

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