8. Existing and Potential Changes in Himalayan Glaciers: In Climate Change Perspective

The Himalayas contain the largest glacier system outside the Polar regions, serving as a vital water tower for the rivers that drain this massive mountain range and its extensive adjoining alluvial fan. The recent retreat of Himalayan Glaciers has had a significant impact on at least half a billion people. According to the updated glacier inventory data from the Geological Survey of India (GSI; Raina V K and Srivastava D (2008), Glacier Atlas of India. GSI Publication 315) there are more than 9,575 glaciers in the Indian-administered part of the Himalayas, covering an area of approximately 37,000 km². Meanwhile, ICIMOD identifies a staggering 540,000 individual glaciers in the Hindu Kush-Himalayan Region, spanning an area of 60,000 km², with an estimated ice reserve of 6,000 km³. These glaciers release meltwater seasonally into the tributaries of the Indus, Ganges, and Brahmaputra Rivers. Around 300 million people depend upon water from these rivers to sustain agricultural and economic activities on the Indian subcontinent’s plains. Regions where water supply heavily depends on melting snow and ice are projected to experience hydrological disruptions due to recent warming. Beyond being a constant source of water, this glacier system serves as a climate change indicator in the region, influencing river discharge, debris production, and transportation, triggering avalanches, flash floods, and causing siltation in lower valleys. Additionally, it directly and indirectly affects the mountain ecology that sustains life. Historically, Himalayan Glaciers have exhibited substantial fluctuations, a pattern that continues into the present day. The ongoing shrinkage of glaciers due to climate change is expected to bring about a major impact on water resources, precipitating dramatic changes in the environment. This paper provides a brief discussion of some critical aspects of glacier shrinkage and its potential impacts.