Response of Lake Baikal ecosystem to climate forcing and pCO(2) change over the last glacial/interglacial transition

The delta(13)C record of total organic carbon in the Lake Baikal core BDP-9 3-2 over the last glacial/interglacial transition shows remarkable correlat ion 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) l evel. With rapid evolution of the Lake Baikal carbon cycle from full glacia l to full interglacial modes, however, the pCO(2) signal in the Baikal delt a(13)C sedimentary organic matter is inundated by the basin-wide productivi ty signal, in the Holocene. The Baikal diatom abundance record, as a paleot emperature proxy, lags behind the GISP2 ice core delta(18)O temperature pro xy record by ca. 1 ka, possibly reflecting the response time of the Baikal ecosystem to major climatic transitions. There is no lag associated with th e pronounced Younger Dryas cooling, however, suggesting a different forcing mechanism, with a short response time, for this abrupt climatic event in c ontinental interior Asia. The phase difference observed between the diatom abundance and delta(13)C proxies in Lake Baikal care BDP-93-2 suggests thei r 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.