Revision as of 18:40, 7 December 2020

Protection of Himalayan glaciers

Debris cover is not protecting Himalayan glaciers

Neha Madaan, `Debris cover may not protect Himalayan glaciers', September 24, 2017: The Times of India

 The glacier melt areas in the Himalayas are experiencing a significant loss of ice due to global warming, despite the presence of a blanketing layer of debris over half of the area, a new study found. The study , conducted by the Pune-based Indian Institute of Science Education and Research (IISER), focused on the observed rate of ice loss between the melt areas covered under debris and those without, and explained why the areas covered by thick layers of rock and debris are experiencing an equally significant loss of ice as their counterparts.

Such areas comprise 50% of the glacier melt areas in the mountain range, and will continue to lose more ice compared to the debrisfree areas in the long run, the IISER study warned.

According to lead researcher Argha Banerjee, assi stant professor (earth and climate science) at IISER, the typical high and steep valley walls surrounding Himalayan glaciers supply a lot of rock debris, leading to a layer of debris on the lower melt-zone that acts as an insulating blanket, reducing ice melt.

Banerjee told TOI that shrinking glaciers in the Himalayas have a profoundly negative effect on water security, including water needs for agriculture and hydropower generation, for people living in the Indus basin and in the upper reaches of the Ganga-Brahmaputra basin.

Glacial meltwater supply, Banerjee said, acts to sof ten the impact of drought in these areas.

“Glacier shrinkage exposes mountain people to increased risk from hazards like glacial lake outburst floods,“ he said.

The IISER study was recently published in the international journal, `The Cryosphere'.

Melting of glaciers

Melting twice as fast since 2000

Somini Sengupta, June 21, 2019: The Times of India

Climate change is “eating” the glaciers of the Himalayas, posing a grave threat to hundreds of millions of people who live downstream, a study based on 40 years of satellite data has shown.

The study, published in ‘Science Advances’, found the glaciers have lost a foot and a half of ice every year since 2000, melting at a far faster pace than in the previous 25-year period. In recent years, the glaciers have lost about eight billion tonnes of water a year. The study’s authors described it as equivalent to the amount of water held by 3.2 million Olympic-size swimming pools.

The study adds to a growing and grim body of work that points to the dangers of global warming for the Himalayas, which are considered the water towers of Asia and an insurance policy against drought.

In February, a report warned that the Himalayas could lose up to a third of their ice by the end of the century, even if the world fulfills its goal of keeping global average temperatures from rising only 1.50 above preindustrial levels.

That goal, which scientists have identified as vital to avert catastrophic heat waves and other extreme weather events, is nowhere close to being met. Average global temperatures have risen by one degree already in the last 150 years. Greenhouse gas emissions continue to climb. And scientists estimate that we are on track to raise the average global temperature between 30 to 50 Celsius by the end of this century.

Another study, published in May, found that Himalayan glaciers are melting faster in summer than they are being replenished by snow in winter. In the warm seasons, meltwater from the mountains feeds rivers that provide drinking water and irrigation for crops.

In the Himalayas, the loss of glaciers poses two profound risks. In the short term, melting glaciers leave behind rock debris that creates dams, and if these debris dams burst, the resulting floods could destroy villages. In the long term, the loss of glacier ice means the loss of Asia’s future bank of water — a safeguard against periods of extreme heat and drought. Receding glaciers can also threaten the ecosystems they support, which can in turn affect communities in the region.

The latest study, led by researchers at Columbia University, relied on the analysis of satellite images of 650 glaciers across 2,000km of the Himalayas, including recently declassified US spy satellite data. The researchers turned the images into 3D models that showed changes in the area and the volume of the glaciers.

They found that from 1975 to 2000, glaciers lost 10 inches of ice each year. Starting in 2000, the rate of loss doubled, to about 20 inches each year. The study also concluded that while soot from fossil fuel burning is likely to have contributed to the ice melt, the bigger factor was rising temperatures. While temperatures varied across the vast mountain range, on average, they rose faster between 2000 and 2016 compared with earlier years. NYT NEWS SERVICE