The Glaciers on Earth's 'Third Pole' Are Bursting, Causing Deadly Floods

Last week, a glacier in northeastern Afghanistan burst and flooded the Panjshir River basin, killing at least ten people. The floodwater triggered landslides as it carved through the valley and damaged 56 houses, washed out two bridges, wrecked a highway, broke an irrigation canal, and swamped farmland, according to an internal report from the International Center for Integrated Mountain Development (ICIMOD) , an intergovernmental agency based in Nepal. That same week, a glacier in western China released 35 million cubic meters—or 14,000 Olympic swimming pools—of fresh water into the Yarkant River basin, prompting evacuations, Greenpeace East Asia reported. Both disasters struck in places that are not traditionally at risk for glacial outbreak floods, but catastrophes like these seemed poised to become the new normal.

As glaciers heat up, meltwater can pool into lakes at their feet. The resulting glacial lakes sit behind walls of ice and debris collected by the glacier’s downhill slide called terminal moraines. Think of these as natural dams. But those dams can break due to any number of environmental triggers, including rainfall. In the Panjshir flood, an icecap melted, reportedly triggering a small landslide, which then in turn caused a glacial flood.

Glacial lakes are more likely to form if the glaciers they are under intense heat, which is now very common amid global deglaciation. Different altitudes of the Yarkant River Basin have warmed between 2°C and 3.5°C since 1961, according to data that Greenpeace East Asia collected from the Taxkorgan and Shache meteorological stations in west China.

These kinds of floods are increasing in frequency and tend to occur at lower altitudes, where glaciers often sit closer to civilization, said Arun Shrestha, the regional program manager for river basins and cryosphere at ICIMOD.

In the Yarkant River basin, glacial outbursts have increased markedly since 1980s, research from the Chinese Academy of Sciences shows. In the Yarkant River basin, glacial outburst floods have become far more common since the 1990s. And before last week’s Panjshir flood, Shrestha told me, ICIMOD didn’t even consider glacial outbreak flooding a big issue in Afghanistan. Historically, glacial outbreak floods were normally isolated to high-altitude glaciers. But that’s no longer the case.

“In the eastern Himalayas, the glaciers are quite high up. In the western Himalayas and Karkoram [a mountain range in Northwest India and Pakistan], the glaciers are quite low and quite close to the villages. So, outbursts are very dangerous,” said Shrestha.

ICIMOD is now setting the groundwork for the tricky process of mapping and assessing Afghanistan’s glaciers for hazards. Because of the vast number and immense isolation of glaciers, most of the analysis needs to be done by locals trained in the proper methodology and assisted by remote sensing. The Hindu Kush mountain range in Afghanistan contains more than 3,000 glaciers and China has more than 40,000. To the north, climate change’s impact on the glaciers of Central Asia’s Tien Shan mountains, which stretch from Kyrgyzstan to China, also remains poorly understood. The vast size and complex landscapes of the Central Asian region defy generalization. Information on the conditions that lead to glacial outbreak floods, or even the solutions that mitigate the damage, do not easily translate from ecoregion to ecoregion.

But the stakes of understanding these landscapes are now immense. Glacial outburst floods are geomorphic events—catastrophes by definition. And as bad as the floods are, they aren’t the only consequence of climate change on the third pole. A warmer world means less snow and more rain during winter, and quicker glacial melt in spring. Earlier melts and runoff through winter and spring could cause less fresh water resources when demand is highest, in summer and fall.

“We have seen a lot of cases in the Karakorum and western Himalayas where people are already having problems getting enough fresh water to irrigate their farmlands,” said Shrestha. “In that area, the only source of water is glacial melt. Without any irrigation, they will not have any agriculture.”

In Pakistan, Shrestha said, farmers have turned to innovative means of supplying fresh water for irrigation, namely solar-powered pumps and hydraulic ram pumps, which pump without electricity or diesel by capitalizing on water pressure to convey water through the irrigation system.

That’s not enough, said Liu Junyan, a climate and energy campaigner for Greenpeace East Asia, who added in a statement that monitoring of glacial hazards should be strengthened, climate projection modeling needs to be enhanced, and hydraulic engineering that could mitigate flood damage needs to be constructed.

But the mountainous terrain of Central Asia presents a political problem as well as a glacial flooding risk. The mountain ranges themselves are often borders. Funding, innovation, communication, and policies jigsaw unevenly over the region. Shrestha works in Kathmandu, Nepal. But when we spoke, he was in Delhi, India, struggling to work his way through the various hoops of securing a visa into Afghanistan. Once there, his work will require different strategies for different communities in different places. But when asked which problem is more urgent—the flooding or the droughts, which now disturbingly come hand-in-hand—Shrestha balked at the question.

“These are different kinds of problems,” he told me. “One is a slow onset problem, but with deep impact into livelihood, economic conditions, food security, nutrition, etc. Where the other—the flood—is very rapid onset, and very visible.”