Store of freshwater in the Himalayan glaciers is shrinking considerably, reveals a new study. It has raised the alarm by stating that ‘regional water security is under threat’.
Glaciologist Hamish D.Pritchard of the British Antarctic Survey in Cambridge said that glaciers in the mountains are melting faster than they can be replenished by snowfall. Pritchard said glaciers can store water for decades or even centuries before releasing it into rivers. He explained that this provides a steady supply to sustain downhill populations even in times of drought.
Pritchard calculated summertime meltwater volumes and winter snowfall rates using a range of datasets to estimate the extent of the imbalance. It included altitude-adjusted precipitation and temperature records from 1951 to 2007. It also observed changes in glacier volumes from 2000 to 2016.
The glaciologist found that the overall volume of meltwater rushing down the mountains each year from 2000 to 2016 was 1.6 times as much as it would have been if the system were in balance.
Pritchard noted that as the global average temperature continues to increase, summertime glacial melt will continue to outpace snowfall, shrinking the glaciers – until eventually, runoff from the mountains tapers off. “If countries fail to rein in greenhouse gas emissions, the annual meltwater flowing into the region’s rivers could be noticeably decreased by 2090.”
The study also highlights that most glaciers in South Asia’s Hindu Kush region are retreating, however, the consequences for the region’s water supply are unclear. The Hindu Kush Himalayan region provides water for drinking, irrigation and other uses for about 1.5 billion people. Research reveals that at lower elevations, glacial retreat is unlikely to cause significant changes in water availability over the next several decades, but other factors, including groundwater depletion and increasing human water use, could have a greater impact.
Overall, glaciers in the eastern and central regions of the Himalayas are retreating at rates comparable to glaciers in other parts of the world. Researchers agree that variations in climate, in timing, amount and type of precipitation and in glacier behavior and dynamics across the vast Hindu Kush Himalayan region mean that it is challenging to determine exactly how retreating glaciers will affect the water supply in each location.