0885208555 - From GERNER THOMSEN To...

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From: GERNER THOMSEN <[email protected]> To: Keith Briffa <[email protected]> Subject: Ph.D. in Sweden Date: Mon, 19 Jan 1998 06:15:55 +0100 Reply-to: gerner <[email protected]> Dear Keith! I contacted Hakan Grudd last week. He is also positive about a Ph.D. for me in Stockholm. I have tried to make a formulation of a project. Please, read it and let me know what you think. Maybe the project is overlapping with that of Grudd or maybe you have better ideas. It could also be that I have misunderstood some points. I have sent the project formulation to Schweingruber, Grudd and Kalen. I send it to Schweingruber because I already contacted him last week (before I got the message from you). He is also interested in the project and anyway he will get involved if I am going to train in Birmensdorf. Best regards from: Gerner Thomsen Description of project 1. Background Dendroclimatology can be defined as the use of tree rings to study and reconstruct past and present climate (Kaennel & Schweingruber, 1995). Global average surface temperatures have risen by 0.3-0.6 °C since the middle of the 19th century (Folland et al., 1990). Climatologists seek to establish the extent to which this rise may be attributable to an enhanced greenhouse effect and so need to distinguish anthropogenic from 'natural' climate fluctuations (those that would occur without anthropogenic influences) to help them make predictions of future climate changes (Briffa et al., 1996a). Clearly the century-long instrumental record is not long enough to accomplish this. Paleoclimatic fluctuations older than meteorological measurements can be inferred from a variety of data sources, including tree rings, records of vegetation processes (e.g. pollen in lake sediments), records of ice layer in ice cores, historical records, etc. (Eddy, 1992). However, within a time frame of the last two millennia dendroclimatology has shown to be the most powerful tool available to provide globally distributed, annually resolved paleoenvironmental records (Luckman, 1996). The growing influence of dendroclimatology in paleoenvironmental studies can be seen in the fact that almost a third of Bradley and Jones' volume Climate since AD 1500 (Bradley & Jones, 1992) deals with dendrochronology and dendroclimatic reconstruction. Near the polar and altitudinal tree lines, tree growth is mainly dependent on summer temperature. As northern latitudes are regarded as being strongly affected by global climate changes, a network of chronologies is established along the polar tree-line in Eurasia (Briffa et al., 1996b). At specific locations in these northern high-latitude regions it is possible to extend the tree-growth record back beyond the life span of living trees by amalgamating the measurements from overlapping, absolutely-dated series of measurements made on dead wood from historical or archeological provenances or naturally surviving above ground, in peat or alluvial
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sediments, or preserved in lakes. The first pair of (ring-width and density) chronologies, made up from samples of Scots pine (Pinus sylvestris L.) at several locations adjacent to Lake Torneträsk, northern Sweden, have
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0885208555 - From GERNER THOMSEN To...

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