Warming-induced monsoon precipitation phase change intensifies glacier mass loss in the southeastern Tibetan Plateau

Glaciers are key components of the mountain water towers of Asia and are vital for downstream domestic, agricultural, and industrial uses. The glacier mass loss rate over the southeastern Tibetan Plateau is among the highest in Asia and has accelerated in recent decades. This acceleration has been attributed to increased warming, but the mechanisms behind these glaciers' high sensitivity to warming remain unclear, while the influence of changes in precipitation over the past decades is poorly quantified. Here, we reconstruct glacier mass changes and catchment runoff since 1975 at a benchmark glacier, Parlung No. 4, to shed light on the drivers of recent mass losses for the monsoonal, spring-accumulation glaciers of the Tibetan Plateau. Our modeling demonstrates how a temperature increase (mean of 0.39 degrees C center dot dec(-1) since 1990) has accelerated mass loss rates by altering both the ablation and accumulation regimes in a complexmanner. The majority of the post-2000 mass loss occurred during themonsoon months, caused by simultaneous decreases in the solid precipitation ratio (from 0.70 to 0.56) and precipitation amount (-10%), leading to reduced monsoon accumulation (-26%). Higher solid precipitation in spring (+18%) during the last two decades was increasingly important in mitigating glacier mass loss by providing mass to the glacier and protecting it from melting in the early monsoon. With bare ice exposed to warmer temperatures for longer periods, icemelt and catchment discharge have unsustainably intensified since the start of the 21st century, raising concerns for long-term water supply and hazard occurrence in the region.

Automated summary

Glacier mass loss in the southeastern Tibetan Plateau has accelerated due to increased warming, with the majority of the loss occurring during the monsoon months. Changes in precipitation amount and ratio have played a significant role in the mass loss, with increased solid precipitation in spring mitigating the loss. However, prolonged exposure to warmer temperatures has unsustainably intensified ice melt and catchment discharge, raising concerns for long-term water supply and hazards in the region.