• Climate Change

Glacial Lake Floods Threaten Communities in Asia, S. America

Melting mountain glaciers pose a growing flood risk to some 15 million people around the world, researchers said in a report published on Feb. 7, with communities in Asia facing the biggest danger.

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 rushing down mountain valleys.

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

Danger is highest, they report in a study published in the journal Nature Communications, when a large number of people live near 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,” said Stuart Dunning, a physical geographer at Britain’s Newcastle University, and a coauthor of the study.

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

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

In the high mountains of Asia, some 9 million people live near more than 2,000 glacial lakes. In 2021, more than 100 people were killed in India in an outburst flood in its northern mountains.