Glacial lake floods threaten communities in Asia, South America

MELTING mountain glaciers pose a rising flood threat to some 15 million individuals around the globe, researchers mentioned in a report revealed on Tuesday, with communities in Asia going through the largest hazard.

Runoff from melting glaciers usually swimming pools in shallow lakes, held again by rocks and particles. The chance comes when a lake overfills, bursting by its pure barrier and sending a torrent of water dashing down mountain valleys.

Scientists have assessed for the primary time how many individuals globally are in danger from these floods, discovering that greater than half of weak populations dwell in India, Pakistan, China, and Peru.

Hazard is highest, they report in a examine revealed in the journal Nature Communications, when numerous individuals dwell close to a lake.

“Our work does not just focus on the size or number of glacier lakes — no disaster is natural — it is the presence of people, especially vulnerable people, in the landscape that causes a disaster,” mentioned Stuart Dunning, a bodily geographer at Britain’s Newcastle College, and a co-author of the examine.

Glacial lake outburst floods are projected to worsen in a warming local weather.

Collectively, the world’s glaciers misplaced about 332 gigatons of ice a 12 months between 2006 and 2016. Since 1990, the quantity and quantity of glacial lakes worldwide have every elevated by about 50%.

Within the excessive mountains of Asia, some 9 million individuals dwell close to greater than 2,000 glacial lakes. In 2021, greater than 100 individuals had been killed in India in an outburst flood in its northern mountains.

HEATING UP THE HIMALAYAS
In contrast with mountain glaciers in the Alps and North America, Asia’s icy locations will not be as effectively monitored -— most lack long-term observations of how they’ve modified over time.

One of the best-studied glacier in the Himalayas is north India’s Chhota Shigri, which has 20 years of mass stability measurements — the distinction between how a lot ice a glacier positive aspects and losses in a 12 months.

In 2022, India suffered blistering temperatures and close to the tip of the 12 months, scientists headed into the Himalayas to measure Chhota Shigri’s mass.

Their findings, shared with Reuters, revealed the best-studied glacier in the Himalayas had skilled its worst 12 months on file; Chhota Shigri misplaced thrice as a lot mass in 2022 in contrast with its 2002 to 2022 yearly common.

“The impacts are already visible as the glacier is thinning and retreating,” mentioned Farooq Azam, a glaciologist on the Indian Institute of Know-how Indore who screens Chhota Shigri. This will likely be “impactful to downstream water availability in near future”, he mentioned.

Satellite tv for pc observations additionally present that the glaciers in the Himalayas are in a state of general decline.

“The ice is really melting significantly during the last decades – mass loss is accelerating,” mentioned Tobias Bolch, a glaciologist with Graz College of Know-how in Austria.

From 1990 to 2015, glacier protection in the Himalayas shrank by about 11%, based on July 2022 examine.

Throughout the identical time interval, Himalayan glacial lakes elevated by about 9% in quantity, and 14% in space. Greater than 200 lakes now pose a really excessive hazard to Himalayan communities, based on 2022 analysis. — Reuters

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