Two annually-laminated and 230Th-dated stalagmite oxygen isotope (δ18O) records from Dongge Cave, China, provided a high-resolution Asian Summer Monsoon (ASM) history for the past 1200 years. A close similarity between annual band thickness and stable isotope analyses (δ13C and δ18O) suggests the calcite δ18O is most likely a proxy associated with ASM precipitation. The two duplicated stalagmite δ18O records show that the ASM varies at a periodicity of ~220 years, concordant with a dominant cycle of solar activity. A period of strong ASM activity occurred during the Spörer Minimum (1450-1550 A.D.), followed by a striking drop circa 1580 A.D., potentially consistent with the social unrest in the final decades of China's Ming Dynasty (1368-1644 A.D.). Centennial-scale changes in ASM precipitation over the last millennium match well with changes in tropical Atlantic sea surface temperatures (SSTs) and South American summer monsoon precipitation. Our findings suggest that variations in low-latitude monsoon precipitation are probably driven by shifts in the mean position of the intertropical convergence zone (ITCZ), which is further mediated by solar activity and tropical SSTs.
Bibliographical noteFunding Information:
This work was supported by the National Nature Science Foundation of China (Grant nos. 41130210 , 41202123 ), the U.S. Nature Science Foundation (Grant nos. 1103403 ), the National Basic Research Program (Grant nos. 2010CB950100 ), the CAS Strategic Priority Research Program (Grant nos. XDA05080503 ) and the Priority Academic Program Development of Jiangsu Higher Education Institutions . We would also like to thank two anonymous reviewers for their comments.
- Asian Summer Monsoon
- Dongge Cave
- Past millennium