Water for Millions Is Vanishing as Bolivia’s Glaciers Melt

Glaciers in the Bolivian Andes have shrunk 43 percent since 1986 as a result of rising global temperatures, putting millions of people at risk for shortages of drinking water, irrigation, and hydropower.

The losses add up to about 88 square miles of land ice cover, or just under 10 percent of the total area of the world’s tropical glaciers. Glaciers worldwide store about 70 percent of the world’s freshwater.

This is the first study to assess all three of Bolivia’s main glacier ranges, according to the team of British and Bolivian scientists who revealed the dramatic ice loss in research published Thursday in the journal The Cryosphere. The researchers used satellite images to measure the changes in Bolivia’s glaciers, finding that their area diminished from about 205 square miles to 116 square miles between 1986 and 2014.

Based on current trends, the researchers estimated that the glaciers could fade to just 20 square miles by 2100.

The cities of La Paz and El Alto, whose 2.3 million residents make up roughly 20 percent of the Bolivian population, rely on Andean glaciers for between 15 and 30 percent of their water supply, said scientist Simon Cook of Manchester Metropolitan University, the study’s lead author. “The issue of water supply as these glaciers decline, to places like La Paz, has been documented before,” he said. “What we’re saying, perhaps for the first time, is that these glaciers could be almost gone by the end of the century, which creates a significant water risk.”

The dangers don’t stop there. The researchers found that as the glaciers recede, they are creating high altitude lakes that can cause dangerous flooding for mountain communities downstream.

Out of hundreds they mapped, Cook and his colleagues identified 25 glacial lakes in Bolivia that they believe warrant more monitoring for flooding threats. Among other factors, such as size, the lakes are all “very near a steep slope that could shed a rock or snow or ice avalanche into the lake,” said Cook. “It’s like someone jumping into a swimming pool: It creates an overtopping of the lake that can send a flood downstream.”

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The risk for such disasters—called “glacial lake outburst floods” in science and policy circles—is growing as climate change advances. In 2000, flooding from a burst glacial lake in a major barley-growing area of southwestern Tibet lasted three weeks and caused $75 million in damages, destroying more than 10,000 homes and nearly 100 bridges and dikes and led to food shortages in the region.

“We’re aware of floods in the region that have taken place as a result of glacier recession and these lakes bursting out that have washed away roads and villages and so on,” said Cook. But the events have not gotten much attention from the wider Bolivian public or authorities. “My view is the issue of floods from glaciers could well be underestimated, partly because of the remoteness of many of these communities,” he said.