Every summer, people living near the Mendenhall River in Juneau, Alaska, keep a close eye on the water level. When the river level begins to rise rapidly, it’s a sign that Suicide Basin, a small glacier-dammed lake 5 miles up the mountains, has broken through the glacier again and a glacial lake outburst flood is underway.

After nearly 15 straight years of ever-larger and more damaging floods in Alaska’s capital city, the U.S. Army Corps of Engineers is discussing an ambitious and expensive solution: create a permanent drain from the lake that would prevent it from reaching outburst stage.

The initial cost estimates for the project range from US$613 million to $1 billion.

Suicide Basin is just one example of a growing problem from glacial lakes that threaten communities around the world, particularly in the Himalayas and Andes, and is transforming Alaska’s landscape as global temperatures rise.

In a new study, colleagues and I documented the evolution of 140 of the largest glacial lakes in Alaska between 2018 and 2024. We found they are expanding about 120% faster on average today than they were from 1986 to 1999 – more than twice as fast.

Using ice thickness data to reconstruct the shape of the land beneath these glaciers, we found that these glacial lakes could become more than four times larger than they are today as the glaciers melt, increasing the potential........

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