Climate change has turned many glaciers into lakes since 1990, study finds

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The volume of lakes formed by melting glaciers around the world due to climate change has jumped 50% in 30 years, according to a new study based on satellite data.”We know that not all meltwater immediately reaches the oceans,” senior author Dan Shugar, a geomorphologist and associate professor at the University of Calgary, said in a statement.

“But until now, there was no data to estimate how much is stored in lakes or groundwater. ”

The findings, published Monday in Nature Climate Change, will help scientists and governments identify potential dangers to communities downstream of these often unstable lakes, he said. They will also improve the accuracy of sea level rise estimates through a better understanding of how and how quickly water from glaciers reaches the sea.

Between 1994 and 2017, the world’s glaciers, especially in high mountain regions, lost around 6.5 trillion tonnes in mass, according to previous research.

“Over the past 100 years, 35% of the world’s sea level rise has been caused by melting glaciers,” Anders Levermann, climate professor at the Potsdam Institute for Climate Change, told AFP. impact of climate change.

The other main sources of sea level rise are ice caps and the expansion of ocean water as it warms.

A helicopter flies over the Planpincieux glacier near the village of La Palud, in Courmayeur, in Val Ferret, in northwestern Italy, August 6, 2020 (AFP Photo)

Shards of glacial lakes

The average temperature of the Earth’s surface has risen by 1 degree Celsius since pre-industrial times, but high mountain regions around the world have warmed twice as fast, accelerating the melting of glaciers. Unlike normal lakes, glacial lakes are unstable because they are often dammed by ice or sediment made up of loose rock and debris.

When the accumulated water bursts through these accidental barriers, massive flooding can occur downstream.

Known as glacial lake explosions, this type of flooding has been responsible for thousands of deaths over the past century, as well as destruction of villages, infrastructure and livestock, according to the study. The most recent recorded incident was a glacial lake explosion that crossed Pakistan’s Hunza Valley in May.

In January, the United Nations Development Program (UNDP) estimated that more than 3,000 glacial lakes have formed in the Hindu Kush-Himalayan region, 33 of which pose an imminent threat that could affect up to seven million. of people.

The new study, based on 250,000 scenes from NASA’s Landsat satellite missions, estimates the current volume of the glacial lake at more than 150 cubic kilometers (37 cubic miles), equivalent to one-third of the volume of Lake Erie in the States. – United or twice the volume of Lake Geneva.

Ten years ago, it would not have been possible to process and analyze this volume of data, Shugar said.

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