From	Jonathan T. Overpeck	Date	Wed, 8 Mar 2006 15:18:54 -0700
To	Keith Briffa
CC	Richard Alley, Eystein Jansen, Bette Otto-Bleisner, Fortunat Joos, Tim Osborn, Ricardo Villalba
Subject	Fwd: divergence
Hi gang - Richard is raising important issues, and Keith is going to respond in some detail on Friday when he gets back. I am cc'ing this to a broader group of IPCC Chap 6 folks so that we make sure we (chap 6) deal with the issues correctly. I'm hoping that Keith will cc to us all, and we'll go from there. For those just in on the issue raised by Richard. There is a paper written by Rosanne D'Arrigo that apparently casts serious doubt on the ability of tree ring data to reconstruct the full range of past temperature change - particularly temperatures above mid-20th century levels. Chap 6 obviously has to deal with this more in the next draft, so Eystein and I would like to get on top of it starting this week. Keith or Richard - do you have a copy of this paper? Is it accepted? Thanks, Peck >X-Sieve: CMU Sieve 2.2 >Date: Wed, 8 Mar 2006 11:55:46 -0500 (EST) >From: >To: jto@u.arizona.edu >Cc: k.briffa@uea.ac.uk >Subject: divergence > >Peck--Thanks. The big issue may be that you don't just have to convince me >now; if the NRC committee comes out as being strongly negative on the >hockey stick owing to RD'A's talk, then the divergence between IPCC and NRC >will be a big deal in the future regardless. The NRC committee is accepting >comments now (I don't know for how long)... As I noted, my observations >of the NRC committee members suggest rather strongly to me that they now >have serious doubts about tree-rings as paleothermometers (and I do, >too...at least until someone shows me why this divergence problem really >doesn't matter). --Richard -- Jonathan T. Overpeck Director, Institute for the Study of Planet Earth Professor, Department of Geosciences Professor, Department of Atmospheric Sciences Mail and Fedex Address: Institute for the Study of Planet Earth 715 N. Park Ave. 2nd Floor University of Arizona Tucson, AZ 85721 direct tel: +1 520 622-9065 fax: +1 520 792-8795 http://www.geo.arizona.edu/ http://www.ispe.arizona.edu/