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Climate Change Threatens Hindu Kush-Himalayas Waters
Dec 24, 2016

The Hindu Kush-Himalayan region hosts several of Asia’s great river systems, which provide water for drinking, irrigation and other uses for about 1.5 billion people. A committee of experts, including those from NASA, found that at lower elevations, glacial retreat is unlikely to cause significant changes in water availability, but other factors, including groundwater depletion and increasing human water use may have a greater impact.

  • Higher elevation areas could experience altered water flow in some river basins if current rates of glacial retreat continue, but shifts in the location, intensity and variability of rain and snow due to climate change will likely have a greater impact on regional water supplies.
  • The melt-water from glaciers in the Hindu Kush Himalayan region supplements several great river systems such as the Indus, Ganges, and Brahmaputra.
  • Scientific evidence shows that most glaciers in the Himalayan region are retreating, leading to concerns that over time normal glacier melt will not be able to contribute to the region’s water supply each year.
  • There is uncertainty in projections of future changes in precipitation, but shifts in the location and intensity of snow and rain could also impact the rate of glacial retreat.
  • Variation in climate, precipitation and glacial behaviour across the vast Hindu Kush Himalayan region means that it is challenging to determine exactly how retreating glaciers will affect water supply in each location.
  • It is likely that the contribution of glacier melt-water to water supply in the Hindu Kush Himalayan region may have been overestimated in the past, for example by not differentiating between the contributions to water supply of melt-water from glaciers and melt-water from snow.
  • Retreating glaciers over the next several decades are unlikely to cause significant changes in water availability at lower elevations, which depend primarily on monsoon rains.
  • However, for high elevation areas, current glacier retreat rates, if they continue, may alter stream-flow in some basins.
  • Assuming annual precipitation in the form of snow and freezing rain remains the same, the loss of water stored as glacial ice will likely not change the amount of meltwater that supplements rivers and streams each summer.
  • Glacial melt-water can act as a buffer against the hydrologic impacts of a changing climate, such as drought.
  • Water stored as glacial ice could serve as the Himalayan region’s hydrologic insurance.
  • Although retreating glaciers would provide more melt-water in the shorter term as the glacier shrinks, loss of glacier ‘insurance’ could become problematic over the longer term.

Hindu Kush-Himalayan Region

The Hindu Kush Himalayan region extends 3,500 km over all or part of eight countries from Afghanistan in the west to Myanmar in the east. It is the source of ten large Asian river systems—the Amu Darya, Indus, Ganges, Brahmaputra (Yarlungtsanpo), Irrawaddy, Salween (Nu), Mekong (Lancang), Yangtse (Jinsha), Yellow River (Huanghe), and Tarim (Dayan)—and provides water, ecosystem services, and the basis for livelihoods to a population of around 211 million people in the region. The basins of these rivers provide water to 1.3 billion people, a fifth of the world’s population.

The Himalayan range alone has the total snow and ice cover of 35,110 containing 3,735 of eternal snow and ice. The total for the region is not yet calculated. Hills and mountains, particularly the Hindu Kush Himalaya mountain system, have always constituted places where adaptation, mitigation, and resilience are hallmarks of the people and the landscape they inhabit. Since time immemorial, the people of the Himalaya have maintained a rich cultural identity, and have maintained food security and biogenetic diversity within the parameters of their own tradition.

The largest cities in the Hindu Kush Himalaya region number in the millions of inhabitants. The most populous cities include Kabul (Afghanistan), Kathmandu (Nepal), Srinagar (India), Peshawar (Pakistan), Quetta (Pakistan), Xinning (China), and Dehra Dun (India).

Large cities such as Kathmandu, Lhasa or Dehra Dun are growing at rates that double the population of these cities every 10 to 15 years or so. At the other extreme are vast rural areas suffering from the paucity of basic services, and where out-migration has evolved as a survival strategy.

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