Spatiotemporal Patterns of Glacier Recession and Mass Balance of Two Contrasting Western Himalayan Glaciers

The western Himalaya, particularly the regions of Jammu, Kashmir, and Ladakh, host more than 12,000 glaciers that are crucial for the drinking, irrigation, hydropower, and tourism sectors. However, rapid warming has intensified glacier mass loss, threatening regional hydrology and the socioeconomic sectors dependent on glacier-fed streams. Despite this, only a limited number of Himalayan glaciers have been evaluated in terms of mass balance. In this study, two benchmark glaciers, Machoi Glacier draining into the Drass Basin in the cold-arid trans-Himalayan Ladakh and Shishram glacier draining into the temperature Jhelum Basin of Kashmir were selected to assess multi-decadal glacier changes. This study reconstructs long term glacier recession and geodetic mass balance for Machoi (debris-covered) and Shishram (clean-ice) glaciers, located in contrasting climatic and topographic settings of the western Himalaya. Geodetic mass balance from 2001 to 2025 was computed using the MicMac module for ASTER stereo-imagery.

During 1980-2024, Machoi Glacier experienced a 30.8% reduction in area (0.7% a-1) accompanied by a snout retreat of 480 ± 60.8 m (10.9 m a⁻¹), whereas Shishram Glacier lost 24.14% of its area (0.5% a⁻¹) with three terminus lobes retreating 202-431 m. Retreat rates increased markedly after 2010 for both glaciers. Mean surface lowering during 2001-2025 was 19.5 ± 2 m for Machoi, corresponding to a mass loss of 91.8 ± 13 Mt (0.69 m w.e. a⁻¹), and 16.6 ± 2 m for Shishram, translating to a mass loss of 85.5 ± 13.5 Mt (0.6 m w.e. a⁻¹). The Equilibrium line altitude (ELA) of both Machoi and Shishram Glacier exhibited an upward shift, indicating enhanced melt. These findings provide the first long-term comparative evidence of glacier recession and mass loss in clean-ice and debris-covered glaciers in the western Himalaya and establish an essential baseline for glaciohydrological modelling and future water resource planning in glacier-fed catchments.