Millennial scale Asian summer monsoon variations in South China since the last deglaciation
Abstract Characterizing spatiotemporal variability of the Asian summer monsoon (ASM) is critical for full understanding of its behavior, dynamics, and future impacts. The present knowledge about ASM variations since the last glaciation in South China largely relies on several precisely dated speleothem stable oxygen isotope d 18 O records. Although these speleothem d 18 O signals provide useful evidence for regional past environmental changes, their validity for denoting ASM intensity remains a great controversy. The Huguangyan Maar Lake (HML) provides one of the most complete archives of environmental and climatic changes in the tropical subtropical South and East Asia since the last glaciation. Here we document a continuous centennial to millennial scale ASM record over the past 16 ky BP from the high sedimentation rate HML sediments. In contrast with the low amplitude variations of Chinese speleothem derived d 18 O signals and the Chinese loess based monsoon precipitation proxy indexes, our multi proxy records reveal a pattern of high amplitude regional climatic fluctuations, including fine scale oscillations during the Bolling Allerod warming, the 8.2 ka cooling event, and an abrupt climate shift from 6.5 5.9 ka. The existence of Bond like cold/dry events indicates a distinct influence of the North Atlantic circulation on low latitude monsoon changes. The broad comparability between the HML paleo proxies, Chinese speleothem d 18 O records, and the northern hemisphere summer insolation throughout the Holocene, suggests that solar insolation exerts a profound influence on ASM changes. These findings reinforce a model of combined insolation and glacial forcing of the ASM.