Himalayan glaciers are melting twice as fast as last century

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01:00 - Source: CNN

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Himalayan glaciers have been losing almost half a meter of ice each year since the start of this century

Scientists say mass melting could threaten water supplies for hundreds of millions of people in Asia

CNN  — 

Climate change is eating away Himalayan glaciers at a dramatic rate, a new study has revealed.

Spanning 2,000 kilometers and harboring some 600 billion tons of ice, Himalayan glaciers supply around 800 million people with water for irrigation, hydropower and drinking.

But they have been losing almost half a meter of ice each year since the start of this century – double the amount of melting that occurred between 1975 and 2000 – according to the Columbia University researchers behind the study.

Recently, the glaciers have lost around 8 billion tons of water a year – the equivalent of 3.2 million Olympic-size swimming pools, say the researchers. And that could potentially threaten water supplies for hundreds of millions of people across parts of Asia.

As the ice melts it forms large glacial lakes, which are already impacting local communities, according to lead author Joshua Maurer.

“[They] can collapse and result in these huge outburst floods. And these are devastating for downstream communities,” he said.

Short-term, experts predict more of this flooding, but less ice in the glaciers could ultimately lead to drought.

SANTA CRUZ PROVINCE, ARGENTINA - NOVEMBER 27:  Ice calves at the Perito Moreno glacier in Los Glaciares National Park, part of the Southern Patagonian Ice Field, the third largest ice field in the world, on November 27, 2015 in Santa Cruz Province, Argentina. The majority of the almost 50 large glaciers in Los Glacieres National Park have been retreating during the past fifty years due to warming temperatures, according to the European Space Agency (ESA). The United States Geological Survey (USGS) reports that over 68 percent of the world's freshwater supplies are locked in ice caps and glaciers. The United Nations climate change conference begins November 30 in Paris.  (Photo by Mario Tama/Getty Images)
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The researchers reviewed 40 years of satellite observations across India, China, Nepal and Bhutan and found that Himalayan glaciers have been retreating rapidly since 2000 due to an average 1 degree Celsius temperature rise in the region.

“[This is] one of the clearest pictures that we’ve seen yet of how fast [Himalayan] glaciers are losing ice over [this] interval,” Maurer told CNN.

“Atmospheric warming appears to really be the dominant driver of ice loss,” he said, adding that Himalayan glaciers may have lost as much as a quarter of their enormous mass over the past four decades.

Read more: What is climate change? Your questions answered

Jeffrey Kargel, of The Planetary Science Institute, in Arizona, who didn’t work on the study, said the paper was “an excellent contribution to our rapidly and fabulously growing knowledge of Himalayan glaciation.”

This study, published in the journal Science Advances, is the latest to highlight how rising temperatures present a growing threat to people living in glacial regions.

A report published in April warned that most glaciers in Central Europe, Western Canada and the United States could vanish by second half of this century under current ice loss rates.

Earlier this year a study warned that a third of the ice in the Hindu Kush Himalaya region, home to the world’s highest peaks, Mount Everest and K2, could melt by the end of this century.

“In the short-term, such rapid melt rates will mean summer floods become more frequent as river discharge is increased, but the long-term prospect is one of drought as the glacier reservoir becomes depleted,” Duncan Quincey, a professor at the University of Leeds who specializes in glaciology and did not carry out the research, told CNN.

Read more: We’re losing the war on climate change

Chris Rapley, professor of climate science at University College London, who is not connected to this study, told CNN that ice loss is “already undermining the viability of small communities in the Himalayas as they suffer ever more serious water shortages.”

According to Rapley, water shortages in the Himalayas could trigger mass migration – a “daunting” prospect.

“Better for all of us to accelerate to net zero as a matter of the highest priority,” he said.

Net zero means the amount of greenhouse gases emitted into the atmosphere is no more than the amount taken out.

Read: What would life be like in a zero-carbon country?

Joerg Schaefer, co-author of the study and research professor at Columbia’s Earth Observatory, said the only way to slow down the melting was by “cooling the planet.”

He said that target set by the 2015 Paris Agreement to keep global temperatures to well below 2 degrees Celsius above pre-industrial levels, would see continued melting that presented a “pretty devastating scenario for Himalayan glaciers.”

“This study gives you a pretty clear picture of what will happen there in the next 50 years. If [melting] goes on like that, it will be devastating,” he said.