Floods from melting glaciers threaten communities in Asia and South America

Melting mountain glaciers pose an increased risk of flooding for some 15 million people worldwide, researchers said in a report released Tuesday, with communities in Asia facing the greatest danger.

Runoff from melting glaciers often collects in shallow lakes, held back by rocks and debris. The risk arises when a lake overflows its banks, breaking through its natural barrier and sending a torrent of water into the valleys.

Scientists have assessed for the first time how many people in the world are at risk from these floods and found that more than half of the vulnerable populations live in India, Pakistan, China and Peru.

The danger is greater, they report in a study published in the journal Nature Communicationswhen a large number of people live near a lake.

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“Our work is not just about the size or number of glacial lakes; no disaster is natural; it is the presence of people in the environment, especially vulnerable people, that causes a disaster,” said Stuart Dunning, a physical geographer at Newcastle University and co-author of the study.

Flooding from glacial lakes is projected to worsen with warmer weather.

Collectively, the world’s glaciers lost about 332 gigatons of ice a year between 2006 and 2016. Since 1990, the number and volume of the world’s glacial lakes has increased by about 50 percent.

In the high mountains of Asia, some 9 million people live near more than 2,000 glacial lakes. In 2021, more than 100 people died in India in a flood in the northern mountains.

the himalayas

Compared to mountain glaciers in the Alps and North America, Asia’s frozen places are not as well monitored: Most lack long-term observations of how they have changed over time.

The best-studied glacier in the Himalayas is northern India’s Chhota Shigri, which has 20 years of mass balance measurements: the difference between the amount of ice a glacier gains and loses in a year.

In 2022, India suffered from scorching temperatures, and near the end of the year, scientists headed to the Himalayas to measure the mass of Chhota Shigri.

Their findings, shared with Reuters, revealed that it had experienced its worst year on record: the Chhota Shigri lost three times as much mass in 2022 compared to its annual average from 2002 to 2022.

“The impacts are already visible as the glacier thins and retreats,” said Farooq Azam, a glaciologist at the Indian Institute of Technology in Indore who monitors Chhota Shigri. This will have an “impact on the availability of downstream liquids in the near future,” he said.

Satellite observations also show that the Himalayan glaciers are in a general state of decline.

The ice has really been melting significantly in the last few decades, the mass loss is accelerating,” said Tobias Bolch, a glaciologist at the Graz University of Technology in Austria.

From 1990 to 2015, glacier coverage in the Himalayas dropped by about 11%, according to a July 2022 study.

During the same period, the Himalayan glacial lakes increased by about 9% in number and 14% in area. More than 200 lakes now pose a very high danger to Himalayan communities, according to 2022 research.