The consequences for the Himalayan water supply depend heavily on the region’s thousands of glaciers, that in the east and central areas of the region are retreating at accelerating rates similar to those seen in other glacier-clusters around the world, but that in the western Himalayas are more stable and could in fact be growing.
This the the conclusion of a new report from the National Research Council that examines how changes to glaciers in the Hindu Kush-Himalayan region could affect the area’s river systems, water supplies, and the South Asian population as a whole.
The Hindu Kush-Himalayan region covers eight countries across Asia and form the headwaters of several major river systems, including the Ganges, Mekong, Yangtze, and Yellow rivers, rivers that are serving as sources of drinking and irrigation water for roughly 1.5 billion people. Not the first time the Himalayan region has been the focus of research into it’s future water availability, with past reports alarmed at the massive loss of glacier volume, this new report outlines concerns and possible remedies.
The region’s water supplies are likely to be unaffected by changes in the glacial system for the next several decades.
The eastern Himalayas and Tibetan Plateau are warming, and the trend is more pronounced at higher elevations where models suggest that desert dust and black carbon are having a hand in the rapid atmospheric warming, accelerated snowpack melting, and glacier retreat.
But the region is likely to see variations in water supplies from extensive extraction of groundwater resources, population growth, and shifts in water-use patterns before they see any extreme change due to glacier melt. The region, according to the committee behind the report, relies heavily on monsoon precipitation and snowmelt.
That being said, there is the chance that some high elevation areas could have altered seasonal and temporal water flow in some river basins, with the effects of glacier retreat becoming most evident during the dry season, particularly in the west where glacial melt is more important to the local river systems.
Glacial Melt as Climate Insurance
The real issue comes after the next several decades during times of drought or similar climate extremes, the climate noted.
For example, during the 2003 European drought, glacial melt contributions to the Danube River in August were approximately three times greater than the 100-year average, no doubt ensuring the survival of many regions.
The committee believe that water stored as glacial ice is liable to serve as the Himalayan region’s hydrologic “insurance” during such times, adding to streams and rivers when it is most needed for the millions of people that rely upon the flowing lifewater.
Existing Challenges Require Flexible Management
The region is already experiencing issues with water resources management as well as the provision of clean water and sanitation. The changes in climate and water availability, the committee conclude, require small-scale adaptations with effective, flexible management that can adjust to the conditions.
In fact, efforts already in effect that focus on natural hazard and disaster reduction in the region could lead to useful lessons when considering and addressing the impact of glacial retreat and changes in the region’s snowmelt processes.
Many water basins in the region are already stressed due to both social changes and environmental factors, and with increased population expansion expected over the coming decades, these water-stresses are liable to intensify. The impact of climate change on the region will likely only add to the problems in the coming decades.