Killing her, not so softly

Is global warming killing the Himalayan glaciers, including Gangotri-Gaumukh — the origin of Ganga?

Akash Bisht Rishikesh/Delhi

Surendra Rawat is a professional mountaineer from the National Institute of Mountaineering in Uttarkashi. His job took him, for the first time five years ago, to the breathtaking Gangotri glacier near Gaumukh — the fount from where the mighty Ganga gurgles out of the awe inspiring Himalayas. Since then, he has been back many times, and each time, says Rawat, "I have to walk a little more. The glacier is receding at a fast pace with each passing year and the water discharge from the snout is also on the decline." Even the temperature in the region is much warmer than it used to be earlier. Is this phenomenon related to global warming, he asks?

Confirming Rawat’s observations, researchers at the Hemwati Nandan Bahuguna (HNB) University, Srinagar, Uttarakhand, reveal that surface temperatures on the planet have steadily increased over the years. Blaming emissions and increased anthropogenic activities as the probable causes of soaring temperatures, researchers predict a disastrous future for the Gangotri glacier. Receding at a worrying rate post-1971, this glacier has retreated more than 1.25 kilometres since the 1960s.

"In the past, the Gangotri glacier extended up to a place called Sukhi, near village Jhala, which is about 60 kms from the present-day snout," says Professor Saumitra Mukherjee of the School of Environmental Sciences, Jawaharlal Nehru University (JNU), New Delhi.

"The receding glacier will have a catastrophic impact on the water discharge to the river Ganga from the snout," says Professor RC Sharma of HNB University. He predicts big trouble for the millions of inhabitants living in the Gangetic basin. These people depend on the river for fresh drinking water and agricultural, industrial and hydropower needs. Any change in the flow will have a disastrous effect on the agriculture of the entire north Indian region. Dams in Uttarakhand already face shortage of water discharge; this has affected the power generating capacity of the reservoir in the region and there is no electricity in most parts of Garhwal.

When a glacier retreats, it leaves rocky debris, called moraines, which are pushed to the edge by the glacial movement. These moraines provide information about glacial retreats and advances, including the positions of the snout at various points in the glacier’s past. However, these moraines also block water flow from the glacier and form natural dams at the edge of the glacier. A sudden breach in these unstable supra-glacial lakes can cause a Glacial Lake Outburst Flood or GLOF, which can have catastrophic effects downstream. "One such outburst happened in Titong River in Himachal Pradesh, killing more than 24 people and causing immense economic loss. Moreover, 19 such lakes have been formed on the Beas, Chenab, Sutlej and Ravi rivers," explains Sharma.

Some rivers swell up in the summer due to increased melting and cause floods and landslides in the adjoining areas. The excess flow also will eventually result in the rise of the sea-level. Researchers at the School of Oceanographic Studies, Jadavpur University, Kolkata, say that the sea-level is rising at the rate of 3.14 mm annually and 15 per cent of the land in the Sunderbans will sink into the sea within the next 13 years. This will not only impact the inhabitants of the area but will also destroy the natural habitat of the Royal Bengal Tiger.

Glacial retreats also cause rivers to change course and bring about a gradual decrease in its flow. It may even dry up the river. Sharma says that in Himachal Pradesh the water flow has decreased by 25 per cent in almost all the rivers. Four glaciers are in terminal retreat and 15 face extinction.