Independent temperature records since the last deglaciation from the varved sediments of Sihailongwan maar lake, northeastern China

Abstract

Paleotemperature changes since the last deglaciation provide key insights for understanding gradual and abrupt paleoclimate changes and their forcing factors in different climatic backgrounds. However, there are notable discrepancies between different temperature time series. Here we report a high-resolution temperature reconstruction based on branched glycerol dialkyl glycerol tetraethers (brGDGTs) from annually laminated sediments of the Sihailongwan maar lake in northeastern China and compare it with temperature records from pollen and long-chain alkenones. The brGDGTs-based mean lake water temperature reconstruction shows a mean temperature of 6.1 °C for the Older Dryas, followed by an increase of 2.6 °C until the peak of the Bølling-Allerød, a decrease to 7.8 °C during the Younger Dryas, and a warming from the beginning of the Holocene until 6 ka BP, and finally a gradual decrease until modern times. Although seasonal biases and interpretations differ in different proxy-based reconstructions, all records show broadly similar temperature changes since the last deglaciation. The results suggest that the temperature variations recorded in Sihailongwan maar lake are coupled with high latitude ice-sheet dynamics through atmosphere-ocean circulation systems. The gradual temperature changes could be mainly associated with the ice-volume, while the abrupt variations of the temperature could be related to the Atlantic Meridional Overturning Circulation, the intensity of the East Asian winter monsoon and solar activity.