World’s glaciers contain less ice than thought – report

The Rhone glacier and the supply of the Rhone river are seen on an autumn day in Obergoms, Switzerland, October 25, 2021. REUTERS/Denis Balibouse

LONDON, Feb 7 (Reuters) – Advances in satellite tv for pc know-how have revealed that the world’s glaciers comprise considerably much less ice than beforehand thought, in keeping with a study printed in Nature Geoscience on Monday.

The revised estimate reduces world sea degree rise by 3 inches if all glaciers have been to soften. But it surely raises concern for some communities that depend on seasonal soften from glaciers to feed rivers and irrigate crops. If glaciers comprise much less ice, water will run out before anticipated.

Whereas some ice naturally melts all year long, rising temperatures as a consequence of local weather change are rushing up glacier retreat. Between 2000 and 2019, these rivers of ice lost roughly 5.4 trillion tonnes.

Nations are already struggling with disappearing glaciers. Peru is investing in desalination to make up for declining freshwater. And Chile hopes to create artificial glaciers in its mountains.

However, “we have had fairly a poor understanding of how a lot ice is definitely saved in glaciers,” mentioned lead research creator Romain Millan, a glaciologist at Université Grenoble Alpes. Previous analyses, for instance, double-counted glaciers alongside the peripheries of the Greenland and Antarctic ice sheets, overestimating ice quantity.

The Nature Geoscience research assessed how shortly glaciers have been transferring throughout the panorama, or their velocity. Such measurements enable scientists to extra precisely measure quantity, as the way in which glaciers move signifies the place ice is thick or skinny. However accumulating this info has been restricted by know-how.

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Excessive-resolution satellites deployed in recent times, nonetheless, allowed for the primary evaluation of how 98% of the world’s glaciers are transferring, “from small glaciers within the Andes as much as large glaciers in Svalbard and Patagonia,” mentioned Millan.

The work analyzed greater than 800,000 pairs of photographs of glaciers taken between 2017 and 2018, and located that many have been shallower than beforehand assessed. Scientists now estimate there’s 20 % much less glacial ice current with the potential to soften into the ocean and lift sea ranges. Presently, glaciers are liable for 1 mm of annual sea degree rise, or 30% of the yearly improve.

“This is without doubt one of the first actually spectacular outcomes popping out” from satellite tv for pc advances, mentioned Daniel Farinotti, a glaciologist at ETH Zurich not concerned within the analysis.

Millan and his colleagues additionally discovered that Asia’s Himalayas comprise 37% extra ice than beforehand estimated, whereas South America’s Andean glaciers comprise roughly 27% much less ice. Already, Peru’s glaciers have misplaced 40 % of their floor space because the Seventies.

“This can put extra strain on freshwater within the Andes,” he mentioned. “Quite the opposite, water can be safer within the Himalayas.”

Reporting by Gloria Dickie; Modifying by Katy Daigle and Janet Lawrence

Our Requirements: The Thomson Reuters Trust Principles.