Priceless ClimateGate email 682: Tom Wigley tells Michael Mann that his son did a tree ring science fair project (using trees behind NCAR) that invalidated the centerpiece of Mann's work

Email 682

date: Fri Jun 6 14:57:47 2003 from: Keith Briffa subject: Re: EOS text to: "Michael E. Mann"

Mike there is often no benefit in bandying fine points of emphasis and implication- Hence , I think that what you have already drafted is fine. Do not start to dilute or confuse the issue with too much additional detail. The job , as you state , is to place on record the statement of disagreement with the "science(!)" and spin. To this end , it may also be worth stating in less couched terms that merely eyeballing the relative magnitudes of recent versus prior period(s) of large scale warmth, is in itself very limited as a basis for claiming the reality OR OTHERWISE of anthropogenic forcing of the recent warming , if this is done without reference to the uncertainty and causes of these differences. The points you make to Tom are of course very valid , but do not be tempted to guild the lily too much here - stick with your current content Keith

...At 10:03 PM 6/5/2003 -0600, Tom Wigley wrote:Mike, Well put! By chance SB03 [Soon and Baliunas] may have got some of these precip things right, but we don't want to give them any way to claim credit. Also, stationarity is the key. Let me tell you a story. A few years back, my son Eirik did a tree ring science fair project using trees behind NCAR. He found that widths correlated with both temp and precip. However, temp and precip also correlate. There is much other evidence that it is precip that is the driver, and that the temp/width correlation arises via the temp/precip correlation. Interestingly, the temp correlations are much more ephemeral, so the complexities conspire to make this linkage nonstationary. I have not seen any papers in the literature demonstrating this -- but, as you point out Mike, it is a crucial issue. Tom.