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Melting glaciers may contribute less to sea level rise than previously thought

A new look into the geometry of glaciers indicates they may contain less ice than scientists thought.

(CN) — Climate scientists have long warned how much water could be displaced into the ocean by melting glaciers. Now, experts say they have a new idea on just how much that amount could be — and it’s actually a little less than we thought.

Melting glaciers are, in a lot of ways, a bellwether for climate change on Earth. Their size and structure are directly linked to changes in both the atmosphere and the water itself, so their shrinkage can give us some much-needed information — not to mention incontrovertible evidence — on the status of our battle with climate change.

Because of this importance, experts have tried to better understand the consequences of melting glaciers. They are particularly interested in exactly how much ice rests within them, as this information can help explain their contribution to sea level rise and factor into water resource management plans for areas that rely on glaciers.

To aid these efforts, scientists published new research in the journal Nature Geoscience on Monday that reveals a new estimate for how much ice these glaciers contain — and it’s about 20% less than we once believed.

Romain Millan from Université Grenoble Alpes and colleagues collected and analyzed thousands of satellite images in order to build a high-detail map of glacier ice motion. With this data, they calculated the thickness of the glaciers and provided a general estimate on how much ice is trapped in them across the globe.

It had been believed melting glaciers would contribute around 30% of total sea level rise, with the rest coming from thermal expansion and shrinking ice sheets. But Monday's study indicates glaciers' contribution to sea level rise in a full-melt scenario will amount to about 257 millimeters — a little over 10 inches — which is 20% less than earlier estimates.

They even got a better idea on where in the world that water could be coming from. Their results also had some differences to previous estimates on specific regions, with their data pointing to the existence of less ice in places like the Andes of South America and more ice in places like the Himalayas.

Researchers say these results on glacier geometry could be significant enough to justify an entirely new look at our predictions for the evolution of glaciers themselves.

“The large differences between our results and existing estimates suggest that similarities in total ice volume are only fortuitous and that no definitive consensus has been reached yet,” the study authors wrote. “As a consequence, this new view of glacier geometry calls for a re-evaluation of the evolution of the world’s glaciers in numerical models.”

Of course, researchers still stress there is a quite a lot of work to be done. They say they need more direct observations of ice thickness to craft a more detailed picture, most notably in places like the Andes, the Himalayas and the Russian Arctic, which together make up nearly a fifth of the total volume on Earth.

This information and much more, according to researchers, will ultimately prove critical to their ongoing quest to understand as much as possible on these icy giants as they slowly vanish from the world.

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