Orchestrated decline of Asian summer monsoon and Atlantic meridional overturning circulation in global warming period

Abstract

The anthropogenic warming of the Earth��s atmosphere is causing dynamical and thermodynamical changes in the ocean and atmosphere circulation, including the Asian summer monsoon (ASM) and the oxygen isotope compositions of its precipitation. Here we present a high-resolution speleothem �� 18 O record from the Shandong Peninsula, eastern China with an age precision of �� 3 years, which in conjunction with five other existing high-resolution speleothem records from the ASM domain, reveals a robust weakening trend in the ASM during the global warming period, particularly since around the 1970s. During this period, both the decline of the Atlantic Meridional Overturning Circulation inferred from existing model-empirical records and the spatially heterogeneous pattern of global warming inferred from the coupled reanalysis of the 20 th century (CERA-20C) product result in broadly similar changes in moisture flux pattern in the ASM domain. This, in turn, leads to the ASM weakening trend in terms of dynamics, as suggested by the speleothem �� 18 O records.