date: Wed Apr 30 15:57:27 1997 from: Keith Briffa subject: Re: your note and CAPE to: druid@ldgo.columbia.edu (Gordon Jacoby) Gordon I too am not sure where we left our conversation last. Yes I couldn't agree more about PAGES and the million spawning devils that seem to be the product. Somewhere there has to be a balance between self interest and Science good - both for PAGES and the individual- but at the moment I don't know where. There is going to be a CAPE project document and there is supposed to be a high-resolution aspect and Greg Zielinski and I are supposed to organise it. At least we should put in why tree rings are important but what good that does the dendro community I'm honestlty not sure. But to go to science - surely you have talked to Ed about the work I've been doing trying to document and understand the change in sensitivity of northern density (and ring widths) to temperature. I have a manuscript but the problem is a major one and is complicated by the issues of CO2 , temperature thresholds,standardisation regional coverage(i.e. spatial scale),appropriate climate signal etc. etc. Simply we see a loss of decadal scale sensitivity in much of our large spatial average data - and in our recent Russian calibrations. I know you talked about this in a couple of papers and have suggested a recent appearance of moisture sensitivity in your northern American trees. I do not know why this is happening but it seems clearer in the density data. We (at least Fritz) has explored the technological possibilities - i.e. that density is biased by an inability to record maximums correctly in very narrow rings but we do not believe this to be the case. I think some threshold may have been crossed that means the densities are limited in their ability to record high temperatures and of course it could be a drought type response in warm periods. These suggestions do not seem to be the answer - or at least all of the answer. Similar warmth before and less of an underprediction of temperatue then, plus the widespread (though not perfectly synchronous) manifestation of the phenomenon lead me to suspect synergistic influences. I really think that nitrates,CO2.tropospheric ozone - and ,certainly not least, increased uv could each or all be playing some part. As for calibrating transfer functions , I think we have to somehow adjust recent tree growth records or not use recent data in the calibrations! Please would you send me copies of your 1995 paper with Rosanne in Woodwell and Mackenzie,Eds. and the 1991 paper in the Fairbanks meeting proceedings, please. I will fax you a page from the EC report that went to Brussels in March. It refers to these points. Also did you know that you were criticised in a recent paper by Lloyd and Farquhar?(Functional Ecology, 1996,10,4-32. I am trying to get a backlog of stuff out , including our maps of degree day reconstructions in Russia and a short and a longer paper describing the stuff above. At the moment I would be happy if you did not therefore distribute the page I am faxing or this information until I can at least get the manuscripts sent off. We must also talk at length about PAGES and CAPE but I haven't got the time or stomach for it now!! as always best wishes to you Keith At 16:45 29/04/97 -0500, you wrote: >Keith: > >I am not sure where we are in our conversation. I thought you had a few >more comments about my comments. > >Anyway, about your comments on PAGES, etc. That is exactly the issue I was >raising, about CAPE becoming just a second generation of PALE. These narrow >initiatives are an abomination unless it is something unique like the >ice-core program. Why is paleoclimatology evolving into so many sub-systems >and acronyms. Many of them might fit under World Atmosphere Studies Toward >Environment and Circum-Arctic Studies of Holocene. One cynic who had a >brief fling with PAGES thought it was just an additional layer in the >bureaucracy of science. I am not sure I agree with him but the >proliferation of commitees under PAGES seems in danger of going out of >control. Eventually each paleoclimatologist will have their own committee >under GOTSUM (Group Organized To SUpport Me) CAPE should be broadened to >cover more with a single committee and replace some related groups. > >On a more productive science note: I have begun some analyses of the data >from our Taymyr chronologies and there is a noticeable change in response >to climate in recent decades. It is not as clear as the Alaska spruce >situation exactly what is happening but one cannot make simple models >assuming a constant relationship. I would assume you are aware of this and >wonder what your thoughts are. > >Gordon > > >