Climate change: Himalayan glaciers at low altitude melting at faster rate
The low-altitude Himalayan glaciers are losing water at a faster pace than the ones in higher reaches due to rising temperatures creating water risk in these regions, a new study has found.
Himalayan glaciers are a huge reservoir of water that sustain lives of millions of people in India and many rivers including Ganga, Brahmaputra and Indus originate from the glacial ice. While most glaciers are melting only a few have witnessed advancement in recent decades.
A study of 146 glaciers spread over 660sq km in Chandra basin in the western Himalayas has for the first time estimated the loss of volume. This helps in understanding the behaviour of glaciers in the wake of climate change as the overall spread of the glaciers may not fall but water content may go down.
The study published in the international general Annals of Glaciology has been done by Anil V Kulkarni of the Indian Institute of Sciences, Bangalore. Kulkarni was previously with India Space Research Organisation (ISRO) and headed its glacier monitoring unit.
“For the first time, not only in India but globally, we have an estimate of how much volume and mass of glaciers has been lost over a period of time in Chandra basin,” Kulkarni said. “Now we can have similar estimates for other glaciers in the Himalayan region.”
The Chandra basin lost 11.1 gega-tonnes of water from 1984-2012, which is about one-fifth of the estimated volume. However, the loss in smaller and low altitude glaciers was about 67% during the period, the study found.
“I will like to caution that there is no danger of the glaciers vanishing in new future,” Kulkarni said, adding the “small ones” may not be there in the long run. The study, Kulkarni said, helps in better understanding of fresh water stored in the Himalayan glaciers and would be crucial for water resource management to implement necessary mitigation measures.
The team of researchers from different scientific institutes in India estimated mass balance of glaciers in the basin on basis of satellite data. The study covered 146 glaciers in the basin situated in Lahul-Spiti valley of Himachal Pradesh, which has witnessed an up to 2 degree temperature rise in the last century.
As per latest ISRO estimate, there are 34,919 glaciers in the Himalayan region having 75,779 sq kms of glaciated areas in Indus, Ganga and Brahmaputra river basins. The ISRO did not notice any changes in 1,752 glaciers while 18 showed advancement. The remaining are retreating on account of rising emissions and increase in debris.
Kulkarni, in another study, had said that Himalayan glaciers have retreated by about 13% in last four decades with the water loss increasing from 9 gega-tonnes per year in 1975-1985 to 20 GT/year in 2010-2015 period.