Glacier lakes swollen by global warming threaten millions

PARIS

Violent flooding from glacier lakes formed or enlarged by climate change threatens at least 15 million people worldwide, most of them in four countries, researchers said on Feb. 7.

More than nine million people across so-called High Mountain Asia live in the path of potential glacial lake outburst floods, including five million in northern India and Pakistan, they reported in Nature Communications.

China and Peru are also especially exposed to the danger of abrupt flooding from melting glaciers, according to the study, the first global assessment of areas most at risk.

The volume of lakes formed as glaciers worldwide disintegrate due to global warming has jumped by 50 percent in 30 years, according to a 2020 study based on satellite data.

Earth’s average surface temperature has risen nearly 1.2 degrees Celsius since preindustrial times, but high-mountain regions around the world have warmed at twice that pace.

lacier lakes are particularly unstable because they are most often dammed by ice or sediment composed of loose rock and debris. When accumulating water bursts through these accidental barriers, massive flooding can occur downstream.

This kind of flooding has been responsible for thousands of deaths in the last century, as well as the destruction of communities, infrastructure and livestock.

“It’s not the areas with the largest number or most rapidly growing lakes that are most dangerous,” said lead author Caroline Taylor, a doctoral student at Newcastle University in England.

“Instead, it is the number of people, their proximity to a glacial lake, and, importantly, their ability to cope with a flood that determines the potential danger,” she explained.

Thousands of people, for example, have been killed by glacier lake outburst floods in High Mountain Asia but only a handful in North America’s Pacific Northwest, even though that region has twice as many glacial lakes.

Some 90 million people across 30 countries live in 1,089 glacial lake basins, they found. 15 million of them reside within one kilometer of the track an outburst flood would take.

Pakistan is home to more than 7,000 glaciers in the spectacular Himalaya, Hindu Kush and Karakoram mountain ranges, more than anywhere else on Earth outside the poles.

Last summer, on the heels of a two-month heat wave and during sustained rains that followed, raging torrents from melting glaciers in northern Pakistan ripped up thousands of kilometers of roads and railway tracks, destroyed bridges, and washed away entire villages.