Summer temperature fluctuations in Southwestern China during the end of the LGM and the last deglaciation

Abstract

We present a sub-centennial resolution summer temperature record from the SE Tibetan Plateau (Tiancai Lake, SW China, 3900 m a.s.l.) derived from a chironomid stratigraphy covering the last c.19.5 ka. The record highlights the interaction between tropical and high-latitude climate forcing through the changes in atmospheric circulation during the last deglaciation. The scale of the last glacial maximum (LGM) cooling is consistent with other tropical mountain regions at c.5°C and a rapid recovery of temperatures at 19.0 ka is related to changes in adiabatic lapse rates at the end of the glaciation. The overall pattern of change shows that North Atlantic deglaciation climate events (the Heinrich 1 and Younger Dryas cooling events and the Bølling–Allerød warm period) are all recorded, but the influence of the events decline as the deglaciation progresses. We relate these patterns to North Atlantic Deep water ventilating the Southern Ocean and to the consequent movements of the Intertropical Convergence Zone (ITCZ) in the Indian Ocean Basin as transmitted through changes in the southern mid-latitude circulation.