Berlin 2005 – wissenschaftliches Programm
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SYKE: Klima und Energie
SYKE 1: Klima und Energie
SYKE 1.2: Hauptvortrag
Dienstag, 8. März 2005, 14:30–15:15, TU HFT101
800,000 Years of Greenhouse Gas Concentrations from an Antarctic Ice Core — •Thomas Stocker — Physics Institute, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
In the framework of the European Project of Ice Coring in Antarctica (EPICA) 3201 meters of ice have been recovered, and an attempt was made during the field season 2004/2005 to reach bedrock. The ice core from Dome Concordia contains the longest, continuous climate history from a polar ice core, and covers at least eight glacial cycles during the last 800,000 years. Due to the sintering process of snow into ice, air is enclosed in bubbles, and under increased pressure, in clathrates within the ice matrix. Polar ice is an excellent archive of air of the past and thus one of the most important climate archives. The chemical composition of this air is measured on samples of 50 grams and less through a variety of analytical techniques. This yields a reliable reconstruction of the three major greenhouse gases in the atmosphere CO2, CH4, and N2O. The complete record of greenhouse gases in low temporal resolution over the last 700,000 years is presented. For the first time it will become possible to investigate warm periods (interglacials) which are substantially different from the warm periods of the last 400,000 years. The negative radiative forcing associated with reduced greenhouse gas concentrations of these interglacials relative to today can be estimated and used to determine the cooling that would be generated. This allows for a fresh look at climate sensitivity which also determines the warming this planet will experience under continued anthropogenic increase of greenhouse gas concentrations.