A new study
conducted using images made by Landsat satellites used by the USGS has found that Bolivian glaciers shrunk by 43 percent between 1986 and 2014. Based on current trends, the researchers estimated that the glaciers could shrink by more than 90 percent by 2100.
The researchers also found that as the glaciers recede, they are creating high altitude lakes. Some of them are in natural dips in the bedrock; some are accidentally dammed behind walls of glacial debris. All such lakes are susceptible to rockfalls, earthquakes and avalanches that can breach them causing dangerous flooding for mountain communities downstream.
Simon Cook of Manchester Metropolitan University, the study’s lead author said
We mapped hundreds of lakes. Some lakes are very small and pose little risk. Others are very large, but there's little or no possibility that they would drain catastrophically. Others are both large enough to create a big flood, and sit beneath steep slopes or steep glaciers, and could be dangerous. It’s like someone jumping into a swimming pool: It creates an over topping of the lake that can send a flood downstream.
The risk for glacial lake outburst floods has increased substantially in the past decade as climate change advances. Hundreds of potentially dangerous glacial lakes have formed in the Himalayas during the past few decades. In Bolivia, a glacier outburst flood in 2009 washed away farm animals, crops and bridges.
Receding glaciers also endanger the water supply. The melted water from glaciers is an important source of drinking water and hydroelectric power both for the capital La Paz and neighbouring El Alto which has a combined population of more than two million people.