Strongly Heterogeneous Surface‐Water Warming Trends in High Mountain Asia

Abstract High Mountain Asia has experienced significant warming in recent decades. Changes in both temperature and precipitation patterns have strongly impacted regional hydrology, including changes to glaciers, snowmelt, and river systems. Here, we examine long‐term (1994–2023) and high‐resolution (30 m) changes in water‐surface temperature over a large and topographically diverse region encompassing the world's highest mountains. We find that water‐surface temperatures have significantly increased (rates up to 0.3C , average 0.1C ) in the vast majority of the study area—especially in snow‐covered regions—with a noted acceleration over the past decade. While some of this warming can be explained by increasing regional air temperatures, we find that surface water is warming faster than nearby land areas. We posit that changes in the cryosphere have induced strong spatial heterogeneities in surface‐water warming, leading to both drastic increases, but also localized decreases, in surface‐water temperature.