Just got back from Washington a few minutes ago (I think that the presentations went very well) and saw this press release from Wahl and Amman. The points appear to be ones that have been posted up at realclimate before, which we’ve fully considered and, in my opinion, don’t lay a glove on our criticisms. Here are the links as sent to me. I’ll post up some more comments after I’ve had a chance to look at it.
Boulder,CO May 10, 2005 Two new research papers submitted for review by Eugene R. Wahl (Alfred University) and Caspar M. Ammann (National Center for Atmospheric Research) reproduce the recently criticized Mann-Bradley-Hughes (MBH) climate field reconstruction, and invite researchers as well as the public to use the code for their own evaluation of the method. Wahl and Ammann highlight the robustness of the MBH method against numerous modifications. Their detailed analyses (first presented publicly at the American Geophysical Union fall meeting, San Francisco, 2004 and at the American Association of Geographers annual meeting, Denver, 2005) reveal that the highly publicized criticisms of S. McIntyre and R. McKitrick against the “Hockey Stick” climate field reconstruction of MBH (Nature, 1998) are unfounded. Conclusions of temperatures during the 15th century rivaling the late 20th century climate are found to be without statistical and climatological merit, as is the alleged identification of a fundamental flaw that would significantly bias the MBH climate reconstruction towards a hockey stick shape. Wahl and Ammann address each criticism raised by McIntyre and McKitrick (Energy and Environment 2003, 2005 and Geophysical Research Letters 2005) and find that: “⠠High 15th century temperatures are only achieved with statistical models that don’t pass validation tests, and thus lack both statistical and climatological meaning. Using mean 20th century climatology would provide a more successful reconstruction than the results put forth by McIntyre and McKitrick. “⠠If Principle Component analysis of North-American tree ring data is applied appropriately (i.e., with retention of all the relevant climate information contained in the tree ring data), climate reconstructions very similar to MBH are achieved, independent of the reference period applied. This is confirmed by an analysis leading to the same result if all individual tree ring series themselves are included. Code for Reconstruction based on Mann-Bradley-Hughes: http://www.cgd.ucar.edu/ccr/ammann/millennium/MBH_reevaluation.html "Real Climate" elaboration on various issues: http://www.realclimate.org Contact information: “⠠Caspar Ammann, National Center for Atmospheric Research: 303-497-1705, firstname.lastname@example.org “⠠Eugene Wahl, Alfred University: 607-871-2604 email@example.com