Recent accelerated drying in southwest China dominated by anthropogenic aerosol forcing

Abstract

Southwest China (SWC) has experienced a significant drying trend in recent decades, which poses considerable challenges for ecosystems, agriculture, and water resource management. While human activities and internal climate variability are recognized as important factors, their relative contributions and the underlying mechanisms in driving this drying trend remain unclear. Using detection and attribution analysis with multi-model ensemble simulations, this study reveals that anthropogenic aerosol forcing is the dominant driver of the recent accelerated drying in SWC, accounting for 77% (46% to 107% for one standard deviation) of all forcing. A reduction in aerosol emissions in Europe triggers an atmospheric wave train and results in a cyclonic anomaly in the upper troposphere over SWC, which suppresses upward motion and leads to less precipitation. Concurrently, an increase in aerosols over China results in local cooling and anomalous downward motion, creating conditions conducive to drought. Our findings highlight the substantial influence of anthropogenic aerosol emissions on regional climate change.