Enhanced Sensitivity of the Asian Water Tower to La Niña in the 21st Century

Abstract The Tibetan Plateau (TP) is a key water source for downstream Asia, and its rainy‐season precipitation is influenced by the El Niño–Southern Oscillation (ENSO). However, whether this teleconnection has remained stationary over recent decades remains uncertain. Using multi‐source data sets, we examine ENSO‐related precipitation, circulation, and moisture‐transport composites during the pre‐2000 epoch (1979–2000) and the post‐2001 epoch (2001–2023). ENSO lifecycle composites show that El Niño and La Niña are associated with opposite‐signed precipitation responses through changes in Western Pacific Subtropical High (WPSH) displacement and monsoon moisture transport. In the post‐2001 epoch, the sensitivity of the plateau's rainy‐season precipitation to La Niña is enhanced: La Niña‐related wetting and WPSH responses are larger in the composites, with a more westward‐displaced WPSH and enhanced moisture transport toward the plateau.