Long‐Term Snow Avalanche Trends in High Mountain Asia: Climatic Drivers and Impacts

Abstract Devastating snow avalanches are frequent in High Mountain Asia (HMA) yet remain undocumented with climate change impact drivers poorly understood. Here we introduce the first record of 60 million avalanche deposits across 10,701 small catchments, compiled from 33 years of Landsat data from 1990 until 2022 using a snow index. Potential damages from avalanches in areas at risk in HMA include nearly 20% of the buildings and up to 22% of the road network annually blocked by deposits temporarily disconnecting villages from food, energy, medicine, and communication infrastructures. Across 85% of HMA, no long‐term trends of deposits were detected due to variable snow and temperature during winter. Nonetheless, in 15% of the 214 larger aggregated catchments comprising HMA, the number of deposits increased by 10 every year. Multivariate analysis among these increases of deposits and winter snow and temperature parameters from reanalysis data revealed that a few areas of western HMA experienced increases in snow water equivalent (5 mm in three decades) and air temperature (2°C) contributing to the increase of avalanche activity. There, a decrease in snowfall of 50 mm, with an increase of rainfall, contributed to the formation of weak and unstable snowpacks. Most deposit trends could not be explained by snow‐temperature variables because of the complex and variable interactions between avalanches and climate. These results call for an adoption of mitigation measures in HMA to address avalanche impacts on infrastructure and human lives, especially in areas where avalanche occurrence may increase with time due to climate tendencies.