15 Million People Are Under Threat From Glacial Lakes

Global warming is melting the world’s glaciers. We’ve been hearing about this for a while. But what we haven’t been hearing about is the human cost of the dissolving of glaciers. A study out this week in the journal Nature Communications says that 15 million people are under threat globally from flooding caused by overflowing glacial lakes.

People in India, Pakistan, Peru, and China are most at risk, the study says, with the Himalayas and the Andes being hit particularly hard by melting. A 2020 study found that glacial lakes have increased in size by nearly 50 percent around the world. Add to that the fact that downstream populations have grown as well. In the Himalayas, one million people live within six miles of a glacial lake.

Glacial lakes are formed by meltwater as glaciers shrink — scientists expect that half of the world’s glaciers will disappear by the year 2100. When these lakes become overfull, they can burst their banks in what researchers call “glacial lake outbursts,” which in turn release angry waters that quickly flood anything in its downward path. Their destructive power is immense, capable of flattening dams, homes, and entire towns. And it’s difficult to know when flooding will occur.

“It could happen at any point,” Rachel Carr, a glaciologist at Newcastle University and an author of the study, told BBC News. “That’s what makes them particularly dangerous, because it’s hard to predict exactly when they will happen."

Many of the most vulnerable places to glacial flooding are in underdeveloped regions such as the Andean areas of Peru, which means early warning systems and emergency responses are often lacking.

Unfortunately, the study also found that while the Andean mountain range is the second-most prone area to glacial flooding — and has had an increase of its glacial lakes by 93 percent over the last 20 years — scientists have tended to pay much more attention to the Himalayan region, which has seen an increase of just 37 percent in the same time period.

“The focus over the last few years on high-mountain Asia is good,” Tom Robinson, a risk researcher at the University of Canterbury in New Zealand, told The Washington Post. “But that shouldn’t come at the expense of other places with really high danger as well, such as the Andes.”

In the United States, the Pacific Northwest is considered a hot spot, with its more than 3,000 glacial lakes.

As climate change heats up the planet and wreaks havoc with deadly heatwaves, severe storms, and drought, the threat of glacial lake flooding is now yet another lethal effect to watch for.

But, Robinson told The Washington Post: “It sounds quite dire, but it doesn’t need to be. With thoughtful investment and careful planning,” he said, severe flooding can be avoided.