The world’s shrinking glaciers contain less ice than previously estimated, according to a ground-breaking study that highlights a future of tight water supplies as climate change accelerates.
Scientists for the first time measured the thickness and movement of more than 250,000 mountain glaciers using new satellite imaging techniques. More than 1 million hours of computing time was used to analyze nearly 812,000 pairs of high-resolution photos. By estimating the thickness of a glacier, the scientists were able to more accurately pinpoint the volume of ice it contains.
The survey encompassed 98% of areas on Earth that were covered in glaciers from 2017 to 2018. It found wide variations in ice volume and freshwater reservoirs that hundreds of millions of people depend on for drinking water, agriculture and electricity generation. That includes glaciers never before mapped in areas of New Zealand, South America and Europe, according the paper published in the journal Nature Geoscience on Monday.
Researchers at France’s Institute of Environmental Geosciences and Dartmouth College determined that the Himalayas held 37% more ice than past surveys had found while the Andes in South America contained 27% less.
Those findings could be relatively good news for the 8 million people that live in the upper Indus and Chenab basin of the Himalayas who rely on glacier meltwater for more than half of river flow during dry seasons. The study estimated that glacier water reservoirs there are 17% to 31% larger than thought. Researchers also calculated that glacial water reservoirs are 30% to 87% larger in a less populated sub-basin of the Brahmaputra River in the Himalayas.
“The Himalayas were the exception,” said Mathieu Morlighem, a co-author of the study and professor of earth sciences at Dartmouth. “Almost everywhere [else], we found thinner ice.”
For instance, the 4 million people who live in three catchment basins of the tropical Andes mountains could face water shortages earlier than expected. The scientists discovered that glaciers in that region hold 20% less ice on average than previously estimated and are among the fastest melting.