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Himalayan glaciers retreat, study finds

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The Himalayas are big in every way. For example, they are home to nine of the ten highest peaks in the world, including Mount Everest. They are the source of Asia’s longest river, the Yangtze River. And they represent the third largest deposit of ice and snow in the world, after only Antarctica and the Arctic.

However, after spending millions of years getting bigger, the Himalayas are now getting smaller and smaller, according to researchers at the University of Leeds in England. In a new study published this month in the journal Scientific Reports, they conclude that glaciers in the Himalayas are melting at an “exceptional” rate compared to glaciers elsewhere in the world.

Scientists used satellite images and digital elevation models to reconstruct the size and ice surface of nearly 15,000 glaciers as they would have existed during the last major glacial expansion 400 to 700 years ago, a period known as the Little Ice Age. Since then, they found, glaciers have lost about 40% of their area, from a peak of 28,000 square kilometers to about 19,600 square kilometers today.

At the same time, glaciers have lost between 390 and 586 cubic kilometers of ice, which is equivalent to all the ice that currently exists in the Alps of central Europe, the Caucasus and Scandinavia. Now melted, this ice is responsible for up to 1.38 millimeters of sea level rise around the world, the study concludes.

While these results are alarming in themselves, what is even more concerning, the study says, is the rate at which the ice is melting, which has accelerated dramatically in modern times. The Himalayan ice caps have shrunk 10 times faster in the past four decades than in the previous seven centuries, he observes.

“Our results clearly show that the ice from the Himalayan glaciers is now being lost at a rate at least 10 times the average rate of past centuries,” study co-author Jonathan Carrivick, deputy director of the Geography Faculty of University of Leeds. , said in a Press release. “This acceleration in the rate of loss has only occurred in recent decades and coincides with human-induced climate change.”

Due to differences in geographic features that impact weather patterns and the effects of warming, Carrivick and his colleagues observed different rates of melt at different points in the Himalayan region. For example, glaciers seem to melt most quickly in the east, in areas where glaciers end in lakes, and in places where glaciers have significant amounts of natural debris on their surface.

While the Himalayas may seem remote to people in the West, their glaciers are extremely important to millions of people who live in South Asia. Because they release meltwater that forms the sources of several major rivers that flow through Asia, including the Brahmaputra, Ganges and Indus, their disappearance could threaten agriculture, drinking water and power generation in countries like Afghanistan, Pakistan, India, Nepal, China, Bhutan, Bangladesh and Myanmar.

But the impact is not only regional. When you consider the aforementioned effect of melting glaciers on sea level rise and the damage that rising oceans can cause to coastal communities around the world, it’s global.

“We must act urgently to reduce and mitigate the impact of human-made climate change on glaciers and rivers fed by meltwater,” Carrivick said.

Co-author Simon Cook, Lecturer in Geography and Environmental Sciences at the Scottish University of Dundee, added: “The people of the region are already seeing changes beyond anything that has been observed since. centuries. This research is only the latest confirmation that these changes are accelerating and that they will have a significant impact on entire nations and regions. ”