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The Bogus "Consensus" Argument on Climate Change

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One of the popular rhetorical moves in the climate change debate is for advocates of aggressive government intervention to claim that “97% of scientists” agree with their position, and so therefore any critics must be unscientific “deniers.”

Now these claims have been dubious from the start; people like David Friedman have demonstrated that the “97% consensus” assertion became a talking point only through a biased procedure that mischaracterized how journal articles were rated, and thereby inflating the estimate.

But beyond that, a review in The New Republic of a book critical of mainstream economics uses the exact same degree of consensus in order to cast aspersions on the science of economics. In other words, when it comes to the nearly unanimous rejection of rent control or tariffs among professional economists, at least some progressive leftists conclude that there must be group-think involved. The one consistent thread in both cases—that of the climate scientists and that of the economists—is that The New Republic takes the side that will expand the scope of government power, a central tenet since its birth by Herbert Croly a century ago.

The Dubious “97% Consensus” Claim Regarding Climate Science

Back in 2014, David Friedman worked through the original paper that kicked off the “97% consensus” talking point. What the original authors, Cook et al., actually found in their 2013 paper was that 97.1% of the relevant articles agreed that humans contribute to global warming. But notice that that is not at all the same thing as saying that humans are the main contributors to observed global warming (since the Industrial Revolution).

This is a huge distinction. For example, I co-authored a Cato study with climate scientists Pat Michaels and Chip Knappenberger, in which we strongly opposed a U.S. carbon tax. Yet both Michaels and Knappenberger would be climate scientists who were part of the “97% consensus” according to Cook et al. That is, Michaels and Knappenberger both agree that, other things equal, human activity that emits carbon dioxide will make the world warmer than it otherwise would be. That observation by itself does not mean there is a crisis nor does it justify a large carbon tax.

Incidentally, when it comes down to what Cook et al. actually found, economist David R. Henderson noticed that it was even less impressive than what Friedman had reported. Here’s Henderson:

[Cook et al.] got their 97 percent by considering only those abstracts that expressed a position on anthropogenic global warming (AGW). I find it interesting that 2/3 of the abstracts did not take a position. So, taking into account David Friedman’s criticism above, and mine, Cook and Bedford, in summarizing their findings, should have said, “Of the approximately one-third of climate scientists writing on global warming who stated a position on the role of humans, 97% thought humans contribute somewhat to global warming.” That doesn’t quite have the same ring, does it? [David R. Henderson, bold added.]

So to sum up: The casual statements in the corporate media and in online arguments would lead the average person to believe that 97% of scientists who have published on climate change think that humans are the main drivers of global warming. And yet, at least if we review the original Cook et al. (2013) paper that kicked off the talking point, what they actually found was that of the sampled papers on climate change, only one-third of them expressed a view about its causes, and then of that subset, 97% agreed that humans were at least one cause of climate change. This would be truth-in-advertising, something foreign in the political discussion to which all AGW issues now seem to descend.

The New Republic’s Differing Attitudes Towards Consensus

The journal The New Republic was founded in 1914. Its website states: “For over 100 years, we have championed progressive ideas and challenged popular opinion….The New Republic promotes novel solutions for today’s most critical issues.”

With that context, it’s not surprising that The New Republic uses the alleged 97% consensus in climate science the way other progressive outlets typically do. Here’s an excerpt from a 2015 article (by Rebecca Leber) in which Republicans were excoriated for their anti-science stance on climate change:

Two years ago, a group of international researchers led by University of Queensland’s John Cook surveyed 12,000 abstracts of peer-reviewed papers on climate change since the 1990s. Out of the 4,000 papers that took a position one way or another on the causes of global warming, 97 percent of them were in agreement: Humans are the primary cause. By putting a number on the scientific consensus, the study provided everyone from President Barack Obama to comedian John Oliver with a tidy talking point. [Leber, bold added.]

Notice already that Leber is helping to perpetuate a falsehood, though she can be forgiven—part of David Friedman’s blog post was to show that Cook himself was responsible (Friedman calls it an outright lie) for the confusion regarding what he and his co-authors actually found. And notice that Leber confirms what I have claimed in this post, namely that it was the Cook et al. (2013) paper that originally provided the “talking point” (her term) about so-called consensus.

The point of Leber’s essay is to then denounce Ted Cruz and certain other Republicans for ignoring this consensus among climate scientists:

All this debate over one statistic might seem silly, but it’s important that Americans understand there is overwhelming agreement about human-caused global warming. Deniers have managed to undermine how the public views climate science, which in turn makes voters less likely to support climate action.

Now here’s what’s really interesting. A colleague sent me a recent review in The New Republic of a new book by Binyan Appelbaum that is critical of the economics profession. The reviewer, Robin Kaiser-Schatzlein, quoted with approval Appelbaum’s low view of consensus in economics:

Appelbaum shows the strangely high degree of consensus in the field of economics, including a 1979 survey of economists that “found 98 percent opposed rent controls, 97 percent opposed tariffs, 95 percent favored floating exchange rates, and 90 percent opposed minimum wage laws.” And in a moment of impish humor he notes that “Although nature tends toward entropy, they shared a confidence that economies tend toward equilibrium.” Economists shared a creepy lack of doubt about how the world worked. [Kaiser-Schatzlein, bold added.]

Isn’t that amazing? Rather than hunting down and demonizing Democratic politicians who dare to oppose the expert consensus on items like rent control—which Bernie Sanders has recently promoted—the reaction here is to guffaw at the hubris and “creepy lack of doubt about how the world [works].”

Conclusion

From the beginning, the “97% consensus” claim about climate change has been dubious, with supporters claiming that it represented much more than it really did. Furthermore, a recent book review in The New Republic shows that when it comes to economic science, 97% consensus means nothing, if it doesn’t support progressive politics.

Originally published at the Institute for Energy Research

Robert P. Murphy is a Senior Fellow with the Mises Institute. He is the author of many books. His latest is Contra Krugman: Smashing the Errors of America's Most Famous KeynesianHis other works include Chaos Theory, Lessons for the Young Economist, and Choice: Cooperation, Enterprise, and Human Action (Independent Institute, 2015) which is a modern distillation of the essentials of Mises's thought for the layperson. Murphy is co-host, with Tom Woods, of the popular podcast Contra Krugman, which is a weekly refutation of Paul Krugman's New York Times column. He is also host of The Bob Murphy Show.

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