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MELTING mountain glaciers pose a rising flood danger to some 15 million individuals all over the world, researchers mentioned in a report printed on Tuesday, with communities in Asia dealing with 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 speeding 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 susceptible populations dwell in India, Pakistan, China, and Peru.
Hazard is highest, they report in a examine printed within the journal Nature Communications, when a lot of individuals dwell close to a lake.
“Our work doesn’t simply concentrate on the scale or variety of glacier lakes — no catastrophe is pure — it’s the presence of individuals, particularly susceptible individuals, within the panorama that causes a catastrophe,” 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 yr 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 within the Alps and North America, Asia’s icy locations aren’t as properly monitored -— most lack long-term observations of how they’ve modified over time.
The perfect-studied glacier within the Himalayas is north India’s Chhota Shigri, which has 20 years of mass steadiness measurements — the distinction between how a lot ice a glacier good points and losses in a yr.
In 2022, India suffered blistering temperatures and close to the top of the yr, scientists headed into the Himalayas to measure Chhota Shigri’s mass.
Their findings, shared with Reuters, revealed the best-studied glacier within the Himalayas had skilled its worst yr on report; Chhota Shigri misplaced 3 times as a lot mass in 2022 in contrast with its 2002 to 2022 yearly common.
“The impacts are already seen because the glacier is thinning and retreating,” mentioned Farooq Azam, a glaciologist on the Indian Institute of Expertise Indore who displays Chhota Shigri. This will probably be “impactful to downstream water availability in close to future”, he mentioned.
Satellite tv for pc observations additionally present that the glaciers within the Himalayas are in a state of total decline.
“The ice is de facto melting considerably over the past many years – mass loss is accelerating,” mentioned Tobias Bolch, a glaciologist with Graz College of Expertise in Austria.
From 1990 to 2015, glacier protection within the Himalayas shrank by about 11%, in keeping with 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, in keeping with 2022 analysis. — Reuters
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