Modeling Glacier Evolution Across Different Climatic Regions of High Mountain Asia

In High Mountain Asia (HMA), glacier meltwater plays a critical role in regulating seasonal river discharge and supporting water availability for populations living in mountainous and downstream regions. Observed acceleration in glacier mass loss over recent decades, together with projected future warming and changes in precipitation, is expected to modify the timing and magnitude of meltwater contributions, with significant implications for regional water security, sustainable development, and glacier-related hazards. To quantify glacier responses to climate change under different emission scenarios, we model glacier evolution across diverse climatic settings in HMA, including the Central Karakoram, Tibetan Plateau, and Central Himalaya. We use a MOno-Layer Higher-Order ice-flow model within the Ice-sheet and Sea-level System Model on an unstructured triangular finite-element mesh, locally refined at high spatial resolution (30–500 m) based on present-day observed surface velocities. We use a nonlinear Budd friction law and the basal friction coefficients are inferred using surface velocity observations from 2022. Surface mass balance (SMB) is computed using a temperature-index method that explicitly accounts for debris cover effects. The SMB model is calibrated against geodetic mass-balance estimates derived from stereo imagery (2000–2020) and validated using satellite altimetry observations (2003–2023). We simulate the glacier evolution from 2000 to 2100 under SSP1-2.5, SSP2-4.5, SSP3-7.0, and SSP5-8.5 using climate forcing from five global climate models (GCMs). Based on ensemble of all five GCMs, glaciers are projected to loose 10 ± 16% (SSP1-2.5) to 98 ± 2% (SSP5-8.5) of their mass by 2100, relative to 2000 across the regions. Among all studied region Monumaha Ice field and Purogangri Ice Cap on Tibetan Plateau exhibit a maximum mass loss of up to 70 ± 22 to 98 ± 2%. We find that on individual glaciers mass change debris cover play an important role, particularly in Central Karakoram region where debris cover delayed the mass loss by 15% by the end of 2100. One of the major takeaways for our study is that compared to earlier studies based on flowline models, our estimates show that glacier mass change differs significantly