Regional Millennial-Scale Summer Monsoon Fluctuations From Southeast Asia During Heinrich Stadials

Abstract

The South Asian Summer Monsoon (SASM) is an important component of the global climate system that plays a key role in controlling precipitation patterns in South Asia. Orbital and millennial-scale SASM precipitation changes have been linked to boreal high-latitude summer insolation and North Atlantic climate fluctuations, respectively. However, the underlying causes for the heterogeneous spatial precipitation patterns attributed to the SASM remain debated. Here, we report a SASM paleoprecipitation record for the past 42 Kyr from the northwest South China Sea based on multiproxy evidence. Our results indicate that SASM precipitation in Southeast Asia varied following the regional summer insolation but with muted millennial-scale fluctuations, in contrast to the evolution of other Asian monsoon regions. Transient climate simulations reveal that the regional orbital insolation generated a tripole precipitation pattern over East Asia by influencing atmospheric circulation during the beginning of the last deglaciation, with high orbital insolation driving increased precipitation in Southeast Asia. Our study highlights the influence of regional insolation in shaping Southeast Asian precipitation patterns on both orbital and millennial timescales.