cc: mann@psu.edu, "raymond s. bradley" , Keith Briffa date: Fri, 17 Nov 2006 16:35:34 -0700 from: Malcolm Hughes subject: Re: Bristlecone pines to: Martin Juckes Martin Juckes wrote: > Hello Prof. Hughes, > > I'm involved in a discussion with Stephen McIntyre about Bristlecone pines, > which I have used as temperature proxies in a recent work > (http://www.copernicus.org/EGU/cp/cpd/2/1001/cpd-2-1001.htm). > > I've read the NAS report section on this issue, and most of the references > cited in the paragraph about bristlecones. I'm unimpressed by the evidence > presented to support the idea that these valuable records of past climate > should be discarded. In particular, the most relevant study appears to be > that of Bunn et al., and this clearly shows anomalous strip-bark growth > occurring well before significant atmospheric CO2 rises. Their study used > whitebark pine, which is clearly not the same as bristlecone, but perhaps > closer than the orange trees cited by Graybill and Idso. > > I'm looking for further literature and if possible data on the issue. Do you > know of any data on anomalous growth in bristlecone strip-bark pines which is > available for analysis? > > sincerely, > Martin Juckes > Dear Dr Jukes, I have been on travel and am extremely busy at the moment. I hope to be able to get back to you on the question of stripbark in the next week or so once I have had a chance to read your paper carefully. One thing I did see in your Table 1 caused me great concern - if you are using a model that assumes each record you use reflects local temperature (which is absolutely NOT the assumption made in MBH98 and 99) the Methuselah Walk and Indian Garden series are without question totally inappropriate, as a careful reading of Hughes and Funkhouser (2003) and a number of very accessible earlier publications going back some decades will show. Methuselah was the *lower* forest border chronology Hughes and Graumlich (1996) and Hughes and Funkhouser (1998) used to reconstruct *precipitation* in Nevada (see http://www.ncdc.noaa.gov/paleo/drought/drght_graumlich.html for the earlier version). I think you will find these two series are not heavily loaded in the ITRDB N. America PC1 used in MBH99. This is a case where detailed knowledge of the original materials is invaluable, and by materials I mean the actual field sites and the wood, not just the derived measurements. I bring this to your attention directly now in the hope it will help you and your co-authors check the effects of this error on your calculations and conclusions in some degree of peace and quiet. I hope this helps! Malcolm Hughes