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

Abstract

The δ 13C record of total organic carbon in the Lake Baikal core BDP-93-2 over the last glacial/interglacial transition shows remarkable correlation with atmospheric CO 2 fluctuations and the negative isotopic shift of 3.5–4‰ 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 δ 13C 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 δ 18O 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 δ 13C proxies in Lake Baikal core BDP-93-2 suggests their independent responses to different forcing mechanisms, further justifying their importance for paleoclimate reconstructions from Lake Baikal records.