John Mashey

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Deep Problems with the Wegman Report

On May 6th, 2010, climate skeptic Christopher Monckton testified before the US House Select Committee on Energy Independence and Global Warming. The hearing was supposed to be on The Foundations of Climate Science. Democrats on the committee invited 4 leading scientists from major US scientific institutions to testify; Monckton was the only witness on the Republican side. Commitee membership is listed online and includes James Sensenbrenner of Wisconsin as the ranking member on the Republican side, who presumably was responsible for selecting Monckton. It's hard to believe the Republicans were even taking the hearing seriously with that choice. Nevertheless, many climate scientists and other observers were quite disturbed by the misinformation provided as testimony by Monckton to the hearing. A comprehensive rebuttal of Monckton's claims was recently put together by leading climate scientists, with sample comments from them including "very misleading", "profoundly wrong", "simply false", "chemical nonsense", and "cannot be supported by climate physics".

HockeyStick.png Unfortunately, this is far from the first time congressional Republicans have perpetrated this sort of stunt. An example with far worse implications is the story of the "Wegman Report", supposedly an analysis of the science underlying scientist Michael Mann's early work on reconstruction of historical temperatures, the so-called "hockey stick" (to the right), which showed that temperatures now are warmer than they have been for many centuries, and getting hotter very fast. Mann's results have been repeatedly reproduced with differing methods by himself and other researchers. A 2006 review by the prestigious National Academy of Sciences determined that, according to data and methods available at that time:

  • It can be said with a high level of confidence that global mean surface temperature was higher during the last few decades of the 20th century than during any comparable period during the preceding four centuries. This statement is justified by the consistency of the evidence from a wide variety of geographically diverse proxies.
  • Less confidence can be placed in large-scale surface temperature reconstructions for the period from A.D. 900 to 1600. Presently available proxy evidence indicates that temperatures at many, but not all, individual locations were higher during the past 25 years than during any period of comparable length since A.D. 900. The uncertainties associated with reconstructing hemispheric mean or global mean temperatures from these data increase substantially backward in time through this period and are not yet fully quantified.
  • Very little confidence can be assigned to statements concerning the hemispheric mean or global mean surface temperature prior to about A.D. 900 because of sparse data coverage and because the uncertainties associated with proxy data and the methods used to analyze and combine them are larger than during more recent time periods.

This NAS report, chaired by Gerald North of Texas A&M University, was actually requested by a congressional Republican - Sherwood Boehlert of NY, who was at the time chair of the House Science Committee. He has since retired - one of the last sensible Republicans in congress.

But other congressional Republicans were not interested in what field scientists had to say, and came up with an alternative report on the "hockey stick". Representatives Joe Barton and Ed Whitfield requested a separate report from statistician Edward Wegman, and had Wegman and colleagues testify to congress about the results. The Wegman report seemed to raise a lot of questions about the "hockey stick" and climate science in general. People who have examined the report in isolation may have been quite impressed by some of its claims - just as those lacking expertise might be impressed by Monckton's song and dance. Now, 4 years after its release, computer scientist John Mashey has done an in-depth study of the report and found a large number of indicators of shockingly low academic quality, and further indications that the report was actually tailored as part of a public relations campaign orchestrated by the usual anti-global-warming suspects (conservative and libertarian think tanks, sponsored by fossil fuel concerns).

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