Glaciers in the eastern and central regions of the Himalayas, appear to be retreating at alarming rates, while those in the western parts are more stable and could be even growing, says a new report.
A study report from the National Research Council examines how changes to glaciers in the Hindu Kush-Himalayan region, which covers eight countries across Asia, could affect the area's river systems, water supplies, and the South Asian population.
The mountains in the region form the headwaters of several major river systems-including the Ganges, Mekong, Yangtze, and Yellow rivers, which serve as sources of drinking water and irrigation supplies for roughly 1.5 billion people.
The entire Himalayan climate is changing, but how this change will impact specific places remains unclear, the committee that wrote the report, said.
The Tibetan Plateau and the eastern Himalayas are warming, and the trend is more pronounced at higher elevations.
Study models suggest that desert dust and black carbon, a component of soot, could contribute to the rapid atmospheric warming, accelerated snowpack melting, and glacier retreat.
While glacier melt contributes water to the region's rivers and streams, retreating glaciers over the next several decades are unlikely to cause significant change in water availability at lower elevations, which depend primarily on monsoon precipitation and snowmelt, the committee said.
Variations in water supplies in those areas are more likely to come from extensive extraction of groundwater resources, population growth, and shifts in water-use patterns.
If the current rate of retreat continues, high elevation areas could have altered seasonal and temporal water flow in some river basins.
The effects of glacier retreat would become evident during the dry season, particularly in the west where glacial melt is more important to the river systems.
Many basins in the region are "water-stressed" due to both social changes and environmental factors, and this stress is projected to intensify with large forecasted population growth, the committee concluded.
