Hockey Stick Argument Summarised

I still get a few climate loons defending the accuracy of the IPCC's iconic, and now infamous, Hockey Stick with one recent know-nothing trying to claim that it actually shows the MWP and LIA.

Steve McIntyre summarises the facts around the statistical demolition of the Hockey Stick, which has led to its derogation by the IPCC and sidelining of its authors - Mann, Bradley and Hughes.

In recent discussion of the Weblog 2007 Awards, several commenters at other blogs have argued that our criticisms of the Mannian parlor tricks have been “thoroughly refuted and discarded by climatologists, published in a credible journal”; that “other professionals in the field who also have “looked in great detail at the problem at hand” and have come to the conclusion that rather than McIntyre’s findings being “valid and relevant”, they instead have found them to be “without statistical and climatological merit”; that CA “fluffed on the whole hockey stick thing”. See for example here

Omitted in these references are the fact that the people described as “climatologists published in a credible journal” or “professionals in the field” are none other than Wahl and Ammann, serial coauthors with Michael Mann, students of Mann, who are not independent of the controversy. Indeed, they largely use (without citation or attribution or even acknowledgment to Michael Mann) arguments originally published at realclimate (and already responded to in MM 2005b(EE). Aside from their lack of independence, neither Ammann nor Wahl qualify as statistical authorities. Ammann did his undergraduate work in geology; Wahl in divinity. While this does not exclude them from having potential insight in the matter, it is evidence that one should not necessarily expect a sure grasp of mathematical and statistical issues and that their conclusions cannot be relied upon uncritically, even if Stephen Schneider accepted their article.

Readers interested in a third party view of the matter are far better off consulting the North Report, the Wegman report, (particularly) Wegman’s Reply to Questions and Richard Smith’s account of the 2006 American Statistical Association session. All of these individuals are vastly more eminent than Ammann and Wahl. Wegman, in particular, has been Chair of the National Academy of Sciences Committee on Theoretical and Applied Statistics and is a legitimate statistical expert. His comments on the Wahl and Ammann preprint are very acute and have not received appropriate consideration.

Read the rest. It's pretty interesting to understand the lack of true peer review undertaken in climate science.

(Nothing Follows)