Response of Lake Baikal ecosystem to climate forcing and pCO2 change over the last glacial/interglacial transition

The delta(13)C record of total organic carbon in the Lake Baikal core BDP-93-2 over the last glacial/interglacial transition shows remarkable correlation with atmospheric CO2 fluctuations and the negative isotopic shift of 3.5-4 parts per thousand in response to the global increase in paleo-pCO(2) level. With rapid evolution of the Lake Baikal carbon cycle from full glacial to full interglacial modes, however, the pCO(2) signal in the Baikal delta(13)C sedimentary organic matter is inundated by the basin-wide productivity signal, in the Holocene. The Baikal diatom abundance record, as a paleotemperature proxy, lags behind the GISP2 ice core delta(18)O temperature proxy record by ca. 1 ka, possibly reflecting the response time of the Baikal ecosystem to major climatic transitions. There is no lag associated with the pronounced Younger Dryas cooling, however, suggesting a different forcing mechanism, with a short response time, for this abrupt climatic event in continental interior Asia. The phase difference observed between the diatom abundance and delta(13)C proxies in Lake Baikal care BDP-93-2 suggests their independent responses to different forcing mechanisms, further justifying their importance for paleoclimate reconstructions from Lake Baikal records. (C) 1999 Elsevier Science B.V. All rights reserved.