Summer warming during Heinrich Stadial 1 in Northeast China

The last deglaciation is considered a key period for exploring the underlying dynamics of temperature changes because it was characterized by multiple millennial-scale abrupt climatic events. However, the limited number of quantitative temperature records in Northeast (NE) China covering the last deglaciation hampers a complete understanding of the mechanisms and processes behind the temperature changes that occurred in that region. Here, we present a quantitative reconstruction of summer temperature over the last deglaciation based on bacterial branched glycerol dialkyl glycerol tetraethers (brGDGTs) analyzed from the sediment sequence of Lake Kielguo, a small volcanic lake in NE China. The results show that summer temperature was lowest during the interval ca. 20-18.2 calibrated (cal.) k.y. B.P. with a value of similar to 11.1 degrees C and increased by similar to 1.9 degrees C during Heinrich Stadial 1 (HS1) and by similar to 2.7 degrees C during the transition to the Bolling-Allerod (B-A). The summer temperatures during the B-A warm interval and Younger Dryas cold interval were similar to 14.1 degrees C and similar to 12.0 degrees C, respectively. The summer temperature record from the Lake Kielguo sediment sequence indicates that summer warming dominated the climate change state during HS1 in East Asia, which is different from the cooling pattern controlled by winter temperatures in the North Atlantic and Greenland realms. This distinction can be explained by weakened winter cooling signals triggered by the collapse of Atlantic Meridional Overturning Circulation when these signals propagated to East Asia, and increased summer temperature warming controlled by orbital and greenhouse gases during HS1 in East Asia.