Penultimate deglaciation Asian monsoon response to North Atlantic circulation collapse

• Published in: Nature Geoscience
• Main Authors: Wassenburg, Jasper A., Vonhof, Hubert B., Cheng, Hai, Martinez-Garcia, Alfredo, Ebner, Pia-Rebecca, Li, Xianglei, Zhang, Haiwei, Sha, Lijuan, Tian, Ye, Edwards, R. Lawrence, Fiebig, Jens, Haug, Gerald H.
• Format: Report
• Language: English
• Published: NATURE PORTFOLIO 2021
• Subjects: ISOTOPIC COMPOSITIONS; STABLE-ISOTOPES; INCLUSION WATER; SUMMER MONSOON; SPELEOTHEM; STALAGMITE; RECORD; TEMPERATURE; DYNAMICS; CAVE; Geology; Geosciences; Multidisciplinary; Indian; North Atlantic
• Online Access: http://ir.ieecas.cn/handle/361006/17212; https://doi.org/10.1038/s41561-021-00851-9

During glacial terminations, massive iceberg discharges and meltwater pulses in the North Atlantic triggered a shutdown of the Atlantic Meridional Overturning Circulation (AMOC). Speleothem calcium carbonate oxygen isotope records (delta O-18(Cc)) indicate that the collapse of the AMOC caused dramatic changes in the distribution and variability of the East Asian and Indian monsoon rainfall. However, the mechanisms linking changes in the intensity of the AMOC and Asian monsoon delta O-18(Cc) are not fully understood. Part of the challenge arises from the fact that speleothem delta O-18(Cc) depends on not only the delta O-18 of precipitation but also temperature and kinetic isotope effects. Here we quantitatively deconvolve these parameters affecting delta O-18(Cc) by applying three geochemical techniques in speleothems covering the penultimate glacial termination. Our data suggest that the weakening of the AMOC during meltwater pulse 2A caused substantial cooling in East Asia and a shortening of the summer monsoon season, whereas the collapse of the AMOC during meltwater pulse 2B (133,000 years ago) also caused a dramatic decrease in the intensity of the Indian summer monsoon. These results reveal that the different modes of the AMOC produced distinct impacts on the monsoon system. The influence of meltwater pulse events on Asian monsoon systems varied in line with the degree of AMOC weakening, according to a multi-proxy analysis of speleothems from China covering the penultimate glacial termination.