date: Mon, 27 Sep 1999 15:18:46 +0100 (GMT Daylight Time) from: Julie Burgess subject: 2nd email to: k.briffa@uea.ac.uk Here is the second email Keith. JB 27 September 1999 Hi I thought it worthwhile to mention an idea that I, and Fritz Schweingruber, have been considering for a while: namely the need to update the circum Arctic network of tree-ring chronologies. All of you have strong research interests in northern boreal forest and it seems to me that we might all share a mutual interest and benefit from discussing the options on how to achieve this. Our own work, as you know, indicates a puzzling drift in the decadal timescale correspondence between falling density values and rising summer temperatures, most apparent in the 30 years leading up to the 1980s. This is juxtaposed with a longer rising trend in basal areas, apparent from around the middle of the 19th century, but which seems to have largely stabilized again in the later part of the current century. What are believed to be unprecedented levels of global warmth (let's say in a 1000-year context) are manifest in the last decade or so (though the details of high latitude warming are open to discussion). This fact alone demands that we explore the nature of tree-growth/climate responses in the most recent decades as extensively as possible. The opportunity to explore time-dependent growth responses and validate previously calibrated transfer functions against certainly unusual background conditions (i.e. increased anthropogenic influence) all point to an urgent need to update our mutual growth data. The work 'mutual' might bring a wry smile to some faces as it is also clear that we have all, for the most part, followed our individual dendroclimatic paths. This brings me to the CAPE (Circum Arctic Palaeo Environments) project: though in principle this incorporates a high-resolution component, in practise it has not, for whatever reason, had any meaningful focus on, or given much direction to, high-resolution (read especially dendroclimatic) research. I do not know what all of your most recent priorities are, but for our part (Fritz, myself, and hopefully Stepan and Eugene) we see the need to continue development of a circum Arctic tree-ring (densitometric) network and a need to improve and update major parts of it. Presumably, many of you think likewise, even if your own interests do not directly revolve around tree-ring-density data. In the next few months, I (with Fritz, Stepan, Eugene and others) will be planning an approach to the European Community for support for selective work that might enable us to achieve some of this in Europe and Siberia. We are also considering how this might also best be done in the U.S. and Canada. Also, what about crucial, somewhat more southerly (but strongly temperature sensitive) regions such as western U.S., Tibet, the European Alps and Mongolia? Is it time to consider a combination of our resources or some form of coordinated approach to multiple funders? I know we have different approaches, opinions, geographical priorities, etc. etc. However, there are surely scientific and practical advantages in considering a more integrated future. The Canadian government, the new PARCs initiative and existing NSF funding sources are probably all being tapped by many of you in N. America. As I said, we will be approaching the EC. What about considering linked proposals? What are the data exchange implications? Would some of you with densitometric equipment be willing to collaborate with Fritz and I and Eugene in updating some sites (Eurasian or N. American or whatever) and exploring recent (potentially age-dependent) changes in densitometric responses across the wider network? The development of longer (Holocene) timescale records of tree-growth and tree-line change would surely benefit from closer collaboration across and between continents. I throw this out to see what you think. the best to all, Keith Briffa ******************************************************** Julie Burgess Climatic Research Unit University of East Anglia Norwich NR4 7TJ Tel. +44 (0)1603 592722 Fax. +44 (0) 1603 507784 CRU web site: http://www.cru.uea.ac.uk/