HR: 1330h
AN: GC12A-0145    [PDF]
TI: Transient Changes in the Global Carbon Cycle During the Last Glacial/Interglacial Transition
AU: Koehler, P
EM: pkoehler@awi-bremerhaven.de
AF: Alfred Wegener Institute for Polar and Marine Research, Columbusstrasse, Bremerhaven, 27568 Germany
AU: * Fischer, H
EM: hufischer@awi-bremerhaven.de
AF: Alfred Wegener Institute for Polar and Marine Research, Columbusstrasse, Bremerhaven, 27568 Germany
AB: The global carbon cycle plays a significant role in glacial/interglacial transitions. On one hand because carbon reservoirs and exchange rates are subject to external climate conditions, on the other hand because changes in carbon dioxide concentrations lead to amplification and mediation of regional climate variations. Time slice experiments were so far unable to unambiguously explain the driving forces of the glacial/interglacial change in atmospheric CO$_2$ of about 100 ppmv. Additional information can be gained from the temporal evolution of the carbon cycle using transient model runs. Here we used a coupled atmosphere/biosphere/ocean box model of the global carbon cycle to quantify changes in CO$_2$ and $\delta^{13}$C observed in Antarctic ice core records. To this end the model is transiently driven by various proxy records over the last 25,000 years. First results show that the estimated increase in the terrestrial biosphere together with the measured atmospheric pCO$_2$ are difficult to reconcile with current theories of oceanic changes in the carbon cycle. In addition a significant role of the biosphere on changes in the isotopic composition of atmospheric CO$_2$ is supported.
DE: 1827 Glaciology (1863)
DE: 4267 Paleoceanography
DE: 4805 Biogeochemical cycles (1615)
DE: 4806 Carbon cycling
SC: Global Climate Change [GC]
MN: 2003 Fall Meeting