Retreat of Machoi Glacier, Kashmir Himalaya between 1972 and 2019 using remote sensing methods and field observations

Abstract

Glaciers in the northwestern Himalayan region of Jammu and Kashmir have been reported to be retreating at higher rates as compared to other parts of the Himalayan arc. This study assessed area changes, frontal retreat, and geodetic mass balance of Machoi Glacier interspersed between the Greater Himalayan mountain range of Kashmir and Zanskar from 1972 to 2019. Further, the cryoconite, albedo, aerosol variability, and sediments in glacier ice were studied to correlate them with glacier recession. The glacier has lost an area of ~1.88 km2 (~29%) from 1972 to 2019 with a frontal retreat of 500 m at a rate of 10.6 m a−1. The geodetic mass balance analysis shows that the glacier surface lowered by 43.7 m losing 0.215 Gt from 2000 to 2011. The cryoconite holes on the glacier are mostly present in the ablation part having an average diameter of 5–7 cm. Both cryoconite holes and light-absorbing impurities in glacier ice show an inverse relation with altitude. Analysis of albedo data indicated no trend for the glacier, however, an insignificant decreasing trend was observed for the ablation zone of the glacier. The seasonal trends of albedo indicated a decrease during winter. The reanalysis data about aerosols indicated a significantly increasing trend from 1980 to 2018 and a decreased concentration in 2019 and 2020 owing to the prevailing COVID19 scenario. The receding glaciers in the region can severely impact the streamflow regimes, hydropower generation, and agriculture production in the region. However, more detailed in-situ data about glacier albedo, lithology, biophysical and chemical characterization of cryoconite holes, anthropogenic footprint and associated aerosol deposition needs to be generated to precisely ascertain their influence on glacier dynamics.