Anti-Phase Oscillation of Asian Monsoons during the Younger Dryas

Significant changes in the global atmospheric and oceanic circulation system occurred during the Younger Dryas cold period. Here we present a late-glacial precipitation proxy record of the East Asian Summer Monsoon, based on the peat cellulose δ13C found in Hani, Northeast China. Both the peat cellulose record and a pollen record from Lake Sihailongwan sediment indicate an abrupt increase in precipitation in the region during the Younger Dryas period. This anomalous rainfall distribution should be considered to indicate the strengthening of the East Asian Summer Monsoon, and its anti-phase variation corresponding to the weakening of the Indian Ocean Summer monsoon during the same period. This agrees with the previously revealed anti-phase variations of the two monsoons during the ice-rafted debris cold events of the North Atlantic Ocean. They all demonstrate that, corresponding to the abrupt temperature drop in the Northern Hemisphere on the centennial to millennial time scale, anti-phase variations of the two Asian summer monsoons occurred.