Richard Tol & The Error-Ridden Mess At Heart Of IPCC Estimates Of Climate's Economic Impacts

[hatrack]

Global warming is, if you'll forgive the pun, possibly the most heated topic of debate this century. While most debate over it focuses on extreme weather, sea level rise and climatic events, there is another part. This is the part that focuses on the economics of global warming. That is, how will global warming affect our wallets? At the forefront of this debate is Richard Tol, professor of economics at the University of Sussex. His work on the economics of global warming is relied upon by climate skeptics like Matt Ridley, who has used it to argue, “Climate change has done more good than harm so far and is likely to continue doing so for most of this century,” based on graphs like:



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Richard Tol was a Coordinating Lead Author for one of the chapters of the IPCC report. His chapter had an entire section added after the the last round of external reviews was completed. Another section received major revisions at the same time. None of these changes were seen by any of the experts who signed up to review the IPCC report. Even worse, the material which was added included two tables and two figures derived entirely from Tol's own work. One table and figure directly cites his 2013 paper, reproducing errors from it. The text of the section referred to it, saying “the initial benefits of a modest increase in temperature are probably positive, followed by losses as temperatures increase further.”

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The corrections to Tol's 2009 paper were more substantial. The notice for it began, “Gremlins intervened in the preparation of my paper “The Economic Effects of Climate Change” published in the Spring 2009 issue of this journal. In Table 1 of that paper, titled “Estimates of the Welfare Impact of Climate Change,” minus signs were dropped from the two impact estimates.” Apparently gremlins caused Tol to flip two negative numbers into positive numbers. There were a number of other corrections, but the most important part of the update was:



“Unlike the original curve (Tol 2009, Figure 1) in which there were net benefits of climate change associated with warming below about 2°C, in the corrected and updated curve (Figure 2), impacts are always negative, at least in expectation.” Tol's new work clearly undermines the conclusions Ridley had relied upon. But even after being forced to make such a major change to his 2009 paper, Tol was once again forced to make more changes when it was discovered there were yet more errors in his work.

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The 2009 paper now cites the IPCC report which cites the 2013 paper which builds upon the work of the 2009 paper, and results being used in the IPCC report are being attributed to the 2013 paper despite them not being present in it. It's all quite confusing.

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http://www.desmogblog.com/2015/08/03/richard-tol-s-gremlins-continue-undermine-his-work

[daleanime]

1. kick, kick, kick....