Antarctica’s Ice Shelves Have Lost Millions of Metric Tons of Ice

https://www.scientificamerican.com/article/antarcticas-ice-shelves-have-lost-millions-of-metric-tons-of-ice/

 

    By Chelsea Harvey, E&E News on August 12, 2020

 
Antarctic ice shelves have lost nearly 4 trillion metric tons of ice since the mid-1990s, scientists say. Ocean water is melting them from the bottom up, causing them to lose mass faster than they can refreeze.

That's according to a new study analyzing satellite data from 1994 to 2018. The results were published yesterday in the journal Nature Geoscience.

That spells bad news for the hundreds of glaciers spread out along the Antarctic coastline.

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Ice shelves are ledges of ice that jut out from the edge of the continent into the ocean. They help to keep glaciers stable, holding them in place.

As ice shelves melt, they become thinner, weaker and more likely to break. When this happens, they can unleash streams of ice from the glaciers behind them, raising global sea levels.

Scientists have grown more concerned about Antarctic ice shelves in recent years. Research increasingly suggests that ice shelves in certain regions of the continent — particularly in West Antarctica and parts of the Antarctic Peninsula — are melting and thinning from the bottom up.

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Research suggests that the continent is losing billions of tons of ice each year. Some of the mass loss comes from melting ice shelves, and some of it comes from melting on the surface of the ice sheet. A majority of it comes from chunks of ice pouring from glaciers into the sea.

And thinning, weakening ice shelves can speed up that process.

Currents of warm ocean water appear to be the culprit. This warm water originates in the Pacific and Indian oceans, flowing south toward Antarctica.

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Modeling studies suggest this process may become more intense in the coming decades as the Earth continues to warm.

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