East Asian monsoon evolution and reconciliation of climate records from Japan and Greenland during the last deglaciation

Abstract

East Asian monsoon (EAM) evolution during the last deglaciation has been shown repeatedly to be aligned with paleoclimatic changes in the North Atlantic, based on climate reconstructions comparing Asian speleothem records with Greenland ice cores. In contrast to this finding, paleoclimatic reconstructions based on Lake Suigetsu sediment cores suggest that past EAM variability in Japan was not always coherent with climatic variability recorded in Greenland ice cores. We resolve this discrepancy using an absolute-dated stalagmite δ 18O record that covers the period between 15.5 and 10.7 thousand years before present (ka, before AD 1950). This stalagmite record is from nearby Maboroshi cave, Japan, and shows climate changes that are synchronous with those of Chinese caves and Greenland ice cores. Our results support an effective teleconnection between low- and high-latitudinal climate systems during the transitions into the Bølling–Allerød (BA) warming at 14.6 ka and the Younger Dryas cooling at 12.8 ka in the North Atlantic. However, our results also indicate monsoonal intensification during the BA, coincident with decreasing temperatures in Greenland from 14.6 to 12.8 ka. We explain this decoupling as a result of the interhemispheric bipolar seesaw climate system. Discrepancies between Lake Suigetsu radiocarbon age data sets and other radiocarbon calibration archives can also be removed when our Maboroshi record is used to adjust the Lake Suigetsu age model, as well as resolving temporal ambiguities in the Lake Suigetsu paleoclimate record.