There has been renewed interest in the Wegman Report, which purported to critique the work of paleoclimatolgists Michael Mann, Raymond Bradley and Malcolm Hughes and their controversial “hockey stick” millennial temperature reconstruction.
Today we’ll take a closer look at Wegman et al’s key passage on tree-ring proxies and do a detailed side-by-side comparison with its apparent main antecedent, chapter section 10.2 in Raymond Bradley’s classic Paleoclimatology: Reconstructing Climates of the Quaternary.
That comparison leaves no doubt that Wegman et al’s explication was substantially derived from that of Bradley, although the relevant attribution appears to be missing. There are, however, several divergences of note, also in the main unattributed, and some of Wegman’s paraphrasing introduces errors of analysis.
But the real shocker comes in two key passages in Wegman et al, which state unsubstantiated findings in flagrant contradiction with those of Bradley, apparently in order to denigrate the value of tree-ring derived temperature reconstructions.
[Update, Dec. 19: This post has been substantially revised to remove speculation about Donald Rapp’s possible role in the Wegman report. I apologize for any embarrassment caused to Donald Rapp or Edward Wegman by that speculation.
The post has also been updated to reflect new information about the provenance of Wegman et al’s section on tree ring proxies, as well as more background detail on some of the events leading up to the Wegman report. There are also more details about large swathes of unattributed material found in the Wegman report and in Donald Rapp’s book Assessing Climate Change.
It is clear that the circumstances and contents of both the Wegman report and Rapp’s text book deserve closer scrutiny.
Dec. 20: Comments are now open again.]
As Climategate devolves into a rerun of old battles about the “hockey stick” graph, I thought I would revisit the roots of that benighted controversy and take a look at the chaotic events of a few years back when the politicization of science (also known as the Republican war on science) really took hold.
I was planning to write another installment of the “In the beginning” series on Steve McIntyre. So I decided to take a look at the infamous Wegman report that Republican congressman Joe Barton relied on to ensure that the “numbers added up” (or not, as he was sure was more likely). The 2006 report was the work of a mysterious “ad hoc” committee led by George Mason University statistics professor Edward Wegman, along with David Scott and Yasmin Said. With its near-veneration for putative hockey-stick destroyers Steve McIntyre and Ross McKitrick, and its scornful denunciation of Michael Mann and his “social network” of like-minded researchers, the report has been a touchstone for contrarians.
But then I started thinking about something that had always bothered me. How could a trio of statistical experts, all on their own, hope to write a report on a field, climate science, of which they had no previous knowledge or experience?
Part of the answer lies in the close examination of the Wegman report. Surprsingly, extensive passages from Wegman et al on proxies have turned up in a skeptic text book by contrarian author Donald Rapp. And at least one of these common passages on tree ring proxies closely follows a classic text by noted paleoclimatologist Raymond Bradley, but with a key alteration not found in the original. Moreover, Wegman’s section on social networks appears to contain some unattributed material from Wikipedia and from a classic sociology text.