Stalagmite multi-proxy records reveal spatial complexity of precipitation and monsoon variability in China over past 60 years

Abstract

Debates surround the reliability of high-resolution stalagmite δ¹⁸O (δ¹⁸Oc) in indicating local precipitation, which complicates discussions about the variations and spatial distribution of precipitation in the Chinese monsoon region. Here, we present stalagmite multi-proxy records (δ¹⁸Oc, δ¹³Cc, Sr/Ca and Ba/Ca) from southwest China with annual resolution from 1959 to 2017 C.E. It is revealed that Asian summer monsoon (ASM) intensity, indicated by δ¹⁸Oc, shows in-phase variation with precipitation in southwest China on the interannual scale. El Niño-Southern Oscillation influences upstream convection and circulation to control variations in ASM intensity and regional precipitation. We used principal component analysis to extract the past 50 years of ASM variation and summer precipitation tripolar spatial pattern from 10 δ¹⁸Oc records. The first principal component revealed a continuous weakening of ASM intensity since 1959 due to global warming and increased El Niño activity. However, precipitation variation patterns and driving factors in southwestern China differ from those in eastern China, suggesting that the spatial distribution of precipitation in Chinese monsoon region is highly complex. Our study provides new insights into the complex relationship between the intensity of the ASM and precipitation in southwest China, offering valuable reference for reconstructing the spatial distribution of precipitation in Chinese monsoon region on longer timescales based on speleothem records.