Millennial-scale Asian summer monsoon variations in South China since the last deglaciation

• Published in: Earth and planetary science letters 2016-10, Vol.451, p.22-30
• Main Authors: Wang, Xisheng, Chu, Guoqiang, Sheng, Mei, Zhang, Shuqin, Li, Jinhua, Chen, Yun, Tang, Ling, Su, Youliang, Pei, Junling, Yang, Zhenyu
• Format: Article
• Language: English
• Subjects: Asian; Asian summer monsoon; bond cycles; Chinese speleothem; Circulation; Cooling; diagenesis; Earth; Glaciology; Insolation; last deglaciation; Monsoons; Oscillations; solar insolation
• ISSN: 0012-821X; 1385-013X
• DOI: 10.1016/j.epsl.2016.07.006

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 (δ18O) records. Although these speleothem δ18O 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 δ18O 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 Bølling–Allerød 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 δ18O 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. •A millennial-scale ASM record in South China over the past 16 ky BP is presented.•We first report all Bond-like cold events in tropical–subtropical regions.•An abrupt climate shift at 6.5–5.9 ka has been recorded by the HML sediments.•Two magnetically depleted intervals correspond to Holocene optimum and BA warming.•We propose a model of combined solar insolation and glacial forcing of the ASM.