In this picture taken on October 19, 2022, a crow flies near the Gaumukh background right meaning cow mouth in Hindi, at Gangotri glacier, believed to be the source of the Ganges River, in Gangotri National Park. PHOTO AFP Melting mountain glaciers poses a growing flood risk to 15 million people around the world, researchers said in a report released on Tuesday, with communities in Asia facing the biggest dangers.
Runoff from melting glaciers often pools in shallow lakes, held back by rocks and debris. The risk comes when a lake overfills, bursting through its natural barrier and sending a torrent of water down mountain valleys.
More than half of the vulnerable populations in India, Pakistan, China and Peru are at risk due to the floods, according to scientists.
In a study published in Nature Communications, they report that the danger is highest when a large number of people live close to a lake.
Stuart Dunning, a physical geographer at Britain's Newcastle University, said that our work does not focus on the size or number of glacier lakes - no disaster is natural - it is the presence of people, particularly vulnerable people, in the landscape that causes a disaster.
Between 2006 and 2016, the world's glaciers lost about 332 gigatonnes of ice a year. The number and volume of glacial lakes in the world has increased by about 50 percent since 1990.
Nearly 9 million people live in the high mountains of Asia, in more than 2,000 glacial lakes. In the year 2021, more than 100 people were killed in India in an outburst flood in its northern mountains.
Compared to mountain glaciers in the Alps and North America, Asia's icy places are not as well monitored - most lack long-term observations of how they have changed over time.
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The best-studied glacier in the Himalayas is North India's Chhota Shigri, which has 20 years of mass balance measurements - the difference between how much ice a glacier gains and loses in a year.
In 2022 India suffered blistering temperatures and scientists went into the Himalayas near the end of the year to measure Chhota Shigri's mass.
Their findings, shared with Reuters, revealed that the best-studied glacier in the Himalayas had suffered its worst year on record, and Chhota Shigri lost three times as much mass in 2022 compared to its 2002 to 2022 yearly average.
Farooq Azam, a glaciologist at the Indian Institute of Technology Indore who monitors Chhota Shigri, said the impacts are already visible as the glacier is thinning and retreating. He said that this will affect downstream water availability in the near future.
Satellite observations show that the glaciers in the Himalayas are in a state of decline.
The melting of the ice is really slowing down during the last decades, according to Tobias Bolch, a glaciologist with the Graz University of Technology in Austria.
From 1990 to 2015, glacier coverage in the Himalayas shrank by 11 percent, according to the July 2022 study.
During the same time period, the Himalayan glacial lakes increased by 9 percent in number and 14 percent in area. According to 2022 research, more than 200 lakes now pose a very high hazard to Himalayan communities.