The world’s largest rivers begin in glaciated mountain regions. However, climate change may cause many glaciers to disappear. Will water become scarce?
There are around 200,000 glaciers worldwide. They play a central role in the water cycle, particularly in the middle and low latitudes, by offsetting runoff fluctuations. Rivers are lifelines on which billions of people depend worldwide, either directly or indirectly.
Will water become scarce in the near or distant future if glaciers become increasingly smaller or disappear completely? Will the Alps, the Himalayas, the Rocky Mountains and the Andes continue to act as water towers? We set out to answer this question in a study of all the earth’s mountain regions and the drainage basins of their large rivers.
We used a glacier model that describes the development of glaciers worldwide and their future runoff until the end of the 21st century. First, the good news: ice-covered mountains will continue to provide enough water throughout the year in future. In an initial phase, climate change will actually cause the runoff to increase, as water stored as ice is released. However, if the glacier becomes too small, it will reach a tipping point, which we call “peak water”.
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Image via Dr. Matthias Huss, ETH Zurich