11. Estimating Recent Glacier Changes in Central Himalaya, India, Using Remote Sensing Data

Changing glacier snout positions, surface area, and mass balance are considered as important indicators of climate change. Climatic warming and cooling are reflected through shrinkage and expansion of glaciers, often without significant time lags. Glaciers are important sources of water supply for lowlands and thus have significant influence on ecosystem services, agriculture, and socioeconomic conditions. The economy of the Indo-Gangetic Plain is particularly vulnerable in this respect. Therefore, the present study assesses recent changes (2001–2013) of glaciers in central Himalayan region using remote sensing data. A total of 31 glaciers were mapped on Landsat ETM+ (2001) and OLI (2013) and compared to estimate the changes in snout positions. The study reveals that there are significant variations in glacier retreat. The retreat rate varies between 5.6 m⁻¹ (Lawan Glacier) and about 35.6 m⁻¹ (Pachu Glacier). A total of 6 glaciers retreated with less than 10 m⁻¹, 16 between 10 and 20 m⁻¹, 6 between 20 and 30 m⁻¹, and 3 more than 30 m⁻¹. An attempt has also been made to assess underlying driving forces of the varying retreat rate of glaciers. The elevation of snouts, the area, and the length of glaciers have implications on snout retreat rate. There are, however, some other important factors, e.g., accumulation area ratio, slope angles of accumulation and ablation, amount of rainfall and snowfall, temperature conditions, and debris cover, that have significant bearings on glacier retreat.