Glaciers: India
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Protection of Himalayan glaciers
Debris cover is not protecting Himalayan glaciers
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
Why some Himalayan glaciers are not melting
Global warming is shrinking glaciers across the world, whether in the Alps or the Himalayas. Except in one spot: the Karakoram mountain range in the northwest Himalayas. Most of the glaciers in this region are stable. Some are even growing.
Modelling fluctuations in glaciers and snowfall over several decades, researchers from the Indian Institute of Education and Research (IISER) in Pune found that variability in snowfall accounts for 60% of changes in glacier mass since 1989.
The findings show that snowfall is the controlling factor in glacier loss in the Himalayas, said Argha Banerjee, study co-author and professor at IISER Pune.
“Now that we know snowfall controls glacier mass so strongly, we can also understand the Karakoram anomaly better,” Banerjee said.
The model showed that although snowfall is reducing in most of the Himalayas due to global warming, it is relatively insensitive to local temperature changes in the Karakoram. (Snowfall affects glaciers both directly and indirectly: Accumulation of snow grows the glacier; more snow cover also means a larger white surface to reflect away sunlight, known as the albedo effect.)
2000-2020: the extent of the melt under estimated by 6.5%
Vaishnavi Chandrasekhar, April 5, 2023: The Times of India
Glacial ice melt in the Himalayas between 2000 and 2020 may be underestimated by approximately 6. 5% , and as much as 10% in central Himalayas, as per a new study published in Nature Geoscience.
Although the differences in mass loss estimations may not seem high, the finding is important because lake-terminating glaciers comprise about 25% glacier area in the Himalayas, said Tobias Bolch, study co-author and professor at Graz University of Technology in Austria.
Such improvements in estimates may be especially important for thewestern Himalayas and Karakoram, where the largest expansion of glacial lakes is expected, the study said.
The study looked at one particular kind of glacier: those that terminate in a lake or a body of water. Glacial lakes are growing in the Himalayas and other high mountain areas due to rising temperatures.
For this study, a team of international scientists used satellite data and formulas to estimate the change in the volume of glacial lakes in the Himalayas for the period between 1990 and 2020 and thus quantify the mass loss happening under the lake as the submerged part of the ice turns into water. They then crosschecked their findings with fieldmeasurements of 16 glacial lakes.
The study found that glacial lakes had increased in number by roughly 47% between 2000 and 2020, or an increase of 179 lakes per decade. Lakes increased by 33% and lake volume by 42% in the same period. The expanding glacial lakes resulted in roughly 2. 7 gigatonnes of under-water ice loss, scientists calculated, adding to the total ice loss numbers.
Most of these “lake-terminating” glaciers are located in the central Himalayas, eastern Himalayas, and the Nyainqêntanglha mountains in Tibet. It is also in these areas where the underestimation of ice loss has been highest, the study found, as glacial lakes have grown.
Parkachik Glacier, Kargil
Esha Roy, July 29, 2023: The Indian Express
A new study by scientists of Wadia Institute of Himalayan Geology has found that three glacial lakes are likely to form around Parkachik Glacier in Ladakh due to rapid ice melt. The glacial melt is worrying as it not only increases chances of glacial lake outbursts but can also lead to paucity of water, glaciers being the region’s primary source of water.
The study, published by Cambridge University Press, is based on satellite imagery between 1971-2021 and supplemented by extensive field surveys between 2015-2021. The group of four scientists, led by Dr Manish Mehta, has found that the glacier retreat varied between 1971 and 2021. Remote sensing data shows that the glacier retreated at an average rate of around two metres per annum between 1971 and 1999, whereas between 1999 and 2021, the retreat was at an average rate of around 12 metres per annum.
Similarly, field observations through day-to-day monitoring suggest that the glacier retreated at a higher rate than observed in satellite imaging, at 20.5 metres per annum between 2015 and 2021.
The Parkachik glacier is one of the largest glaciers in the Suru River valley, covering an area of 53 square km and is 14 km long. The Suru River valley is a part of the southern Zanskar Ranges in the western Himalayas. “There are two main reasons for the rapid melting of the glacier. The first is global warming and increasing temperatures in the region, and the second is that it is at a lower altitude than other glaciers in the Zanskar region,” said Dr Mehta speaking with The Indian Express.
Mehta said scientists found alarming results in the ablation and accumulation in the glacier. Accumulation is at the top of a glacier, indicating the accumulation of snow. Ablation indicates the glacier’s lower half where melting typically takes place.
The study has found that ‘surface ice velocity’ was 45 metres per annum in the lower ablation zone in 1999-2000 which reduced to 32 metres per annum in 2020-21, a reduction of 28 per cent. “According to the models we have used, three proglacial lakes are likely to form near the glacier. This poses two problems. If the volume of water is large, there is a possibility of glacial lake outbursts. While Ladakh in general is thinly populated, there is a cluster of villages near the glacier, and Kargil is barely 80 km away,” Mehta said. The second issue with the glacial retreat is the loss of a valuable water resource since Ladakh primarily depends on glacial melt for water. “In Asia, three billion people are dependent on glaciers for water,’’ Mehta added.
The most catastrophic glacial lake outburst that India has faced in recent years resulted in the 2013 Kedarnath flash floods.
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Glaciers: India
