It’s getting warmer and wetter up there in the Himalayas, and that may not augur well for Himalayan states where riverine disasters, like the recent Uttarakhand floods, have wreaked havoc. New research indicates that although the size of glaciers in the basins of the Indus and the Ganga will decrease in the 21st century, water discharge will, however, increase.
While the results of the research predict a sombre future for Himalayan glaciers, they offer some good news for water and food security in India, Bangladesh, and Pakistan. The rivers in the Himalayas, such as the Indus and the Ganga whose waters depend on the melting of glaciers and snow, are essential to the food supply of hundreds of millions of people in the lower-lying areas.
The latest research led by Walter Immerzeel, a scientist from Utrecht University in the Netherlands and visiting scientist at the International Centre for Integrated Mountain Development (Icimod) in Nepal, indicates that increasing rains would prevent rivers from drying up. Incidentally, Icimod is the same organisation from which the Planning Commission had sought a report on India’s disaster preparedness after the Uttarakhand disaster.
Immerzeel’s study builds on his earlier one which had indicated a worrisome drop in the levels of the same rivers by 2050. But, it is not that Immerzeel has done a turn-around. According to the study, glacial melting will peak sometime around 2070 and glacial discharge will start to drop. However, at that time too the increase in precipitation will compensate for this, as a result of which the annual discharge from the river basin will increase again.
“We are now using a more advanced glacier model that takes into consideration how slowly glaciers respond to climate change,” Immerzeel said. “The key difference is that previous work by our group and other scientists showed that the extent to which precipitation in the western Himalayas increases with altitude is much greater than we previously thought. The computer model used for this research takes these new insights into consideration.” To understand the impact of climate change on river discharge in the Himalayas, Immerzeel and his team created computer models of glacier movements and water balance in two watersheds that vary greatly with regard to the climate and size of glaciers.
Immerzeel and his co-researchers have published their findings, ‘Rising river flows throughout the twenty-first century in two Himalayan glacierized watersheds’ in the latest issue of Nature Geoscience.
