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World's largest ice shelf is melting 10 times faster than the global average

By
Brooks Hays
The Ross Ice Shelf is the largest ice shelf in the world; it's also the fastest melting in the world. Photo by Poul Christoffersen/Cambridge University
The Ross Ice Shelf is the largest ice shelf in the world; it's also the fastest melting in the world. Photo by Poul Christoffersen/Cambridge University

April 29 (UPI) -- Antarctica's Ross Ice Shelf, the largest ice shelf in the world, is melting ten times faster than the global average.

Over the last several years, scientists have been tracking the interactions between the northwest section of the ice shelf and the Southern Ocean. Their analysis suggests an influx of warm ocean water is responsible for the ice shelf's accelerated melt rate.

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"The stability of ice shelves is generally thought to be related to their exposure to warm deep ocean water, but we've found that solar heated surface water also plays a crucial role in melting ice shelves," Craig Stewart, researcher at the National Institute of Water and Atmospheric Research in New Zealand, said in a news release.

Stewart and his research partners drilled a borehole several hundred feet into the ice and deployed an instrument-filled mooring in the ocean water inside the ice shelf's cavity. For four years, scientists measured temperature, salinity, melt rates and ocean currents. The team of researchers also used a custom-made radar system to track the ice shelf's changing thickness.

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The data and analysis -- published this week in the journal Nature Geoscience -- showed that during the summer, water heated by the sun flows into the cavity beneath the ice shelf. The influx of warm water more than triples melt rates at the base of the ice shelf.

"Climate change is likely to result in less sea ice, and higher surface ocean temperatures in the Ross Sea, suggesting that melt rates in this region will increase in the future," said Stewart, who conducted the research while a PhD student at the University of Cambridge.

Conditions inside the ice shelf's cavity are closely tied to ocean and atmospheric changes. Sudden changes in air and ocean surface temperatures can quickly alter the ice shelf's dynamics. Because the ice shelf's cavity is located near a stabilizing pinning point, scientists say a continued influx of warm water could undermine the ice shelf's structural integrity.

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The Ross Ice Shelf might not be as stable as scientists previously estimated. That's bad news for the many glaciers that flow into the ice shelf. If the Ross Ice Shelf were to collapse, the flow of many other glaciers toward the Southern Ocean would likely accelerate.

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