Himalayan glaciers melting at ‘exceptional rate’

Khumbu glacier near Everest Base Camp (stock image).
Credit: © Marek / stock.adobe.com

Researchers from the University of Leeds concluded that Himalayan glaciers have lost ice 10 times faster than on average since the last big glacier growth 400-700 years ago, known as the Little Ice Age.

The study also shows that Himalayan glaciers are disappearing at a rate the researchers describe as “extraordinary” compared to glaciers in other parts of the world. Reconstructions of 14,798 Himalayan glaciers during the Little Ice Age have been published in Scientific Reports. A team of scientists estimate that the glaciers have lost almost 40% of their extent, dropping from a peak of 28,000 km2 to about 19,600 km2 in today’s world.

Between 390 and 586 km3 of ice have been lost over that time, which is the equivalent of all the ice currently housed in the Central European Alps, the Caucasus, and Scandinavia put together. According to the team’s calculations, the amount of water discharged into the ocean as a result of this melting is anywhere from 0.92 mm to 1.38 mm. Deputy Head of the University of Leeds School of Geography Dr Jonathan Carrivick, the corresponding author, said: “Ice loss from Himalayan glaciers is presently occurring at a rate ten times greater than the average rate over the past century, according to our data. Loss rates have risen sharply just in the last few decades, coinciding with the onset of human-caused global warming.”

Because of the Himalayan mountain range’s vast volume of glacier ice, it is sometimes referred to as “the Third Pole” after Antarctica and the Arctic. A huge impact will be seen by hundreds of millions of people who rely on Asia’s major river systems for food and energy as a result of the rapid melting of the Himalayan glaciers. The Brahmaputra, Ganges, and Indus are three of the major rivers in the region.

Glacier extents 400-700 years ago could be “reconstructed” using satellite pictures and computer elevation models created by the research team. The researchers analyzed the geometry of these ridges to estimate the old glacier extent and ice surface elevation using satellite pictures that revealed ridges that marked the former glacier limits. The volume and mass loss between the Little Ice Age and now was calculated by comparing the glacier reconstruction to the current glacier.

Generally speaking, the Himalayan glaciers in eastern Nepal and Bhutan are losing mass at a greater rate than those in the north of the main divide. As a result of variances in geographical characteristics on both sides of the mountain range interacting with the atmosphere, different weather patterns can be observed on each side. In addition, glaciers in the Himalayas are receding more rapidly where they drain into lakes, which has a number of warming implications. The growth in the number and size of these lakes means that mass loss will continue to accelerate.

Additionally, glaciers with a lot of natural debris on their surfaces are shedding mass at a much faster rate than other glaciers, accounting for 46.5 percent of the overall volume loss. Despite the urgent need to decrease and mitigate the impact of human-made climate change on glaciers and meltwater fed rivers, the modeling of that influence on glaciers must also take into account the function of elements such as lakes and debris,” stated Dr. Carrivick. A senior lecturer in Geography and Environmental Science at the University of Dundee, Dr Simon Cook, said: “People in the region are already noticing changes that haven’t been seen in a long time. Those changes are escalating and will have a profound influence on entire countries and regions, according to this latest research.”

Reference : https://www.sciencedaily.com/releases/2021/12/211220083104.htm

Categories: Environmental, Society