December 2, 2022

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Ancient valleys may show how ice sheets will respond to climate change: NPR

Ancient valleys may show how ice sheets will respond to climate change: NPR

Aerial view of icebergs and ice cap near Petovík, Greenland.

Kerem Yucel / AFP via Getty Images


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Kerem Yucel / AFP via Getty Images

Aerial view of icebergs and ice cap near Petovík, Greenland.

Kerem Yucel / AFP via Getty Images

During the Earth’s Ice Ages, most of North America and Northern Europe were covered by massive glaciers.

About 20,000 years ago, those ice sheets began to melt rapidly, and the resulting water had to go somewhere — often, under glaciers. Over time, huge valleys formed under the ice to drain water away from the ice.

The study authors said a new study of how glaciers melted after the last ice age could help researchers better understand how ice sheets respond to extreme warmth as a result of climate change.

The study published this week In Quaternary Science Reviewshelp explain how – and how quickly – these channels were formed.

“Our results show, for the first time, that the most important mechanism is probably summer ice melt at the surface of ice that makes its way into the bed through chimney-like cracks or channels and then flows under ice sheet pressure to cut off ice,” said Kelly Hogan, co-author and geophysicist at the Survey. British Antarctica.

Researchers have found thousands of valleys under the North Sea

By analyzing 3D seismic reflection data originally collected through risk assessments for oil and gas companies, researchers have found thousands of valleys across the North Sea. Those valleys, some of which are millions of years old, are now buried deep in the mud of the sea floor.

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Some of the canals were huge – up to 90 miles wide and three miles wide (“many times larger than Loch Ness”) The UK-based research group noted).

A digital model of a massive canal that carried meltwater away from ancient glaciers.

James Kirkham/British Antarctic Survey


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James Kirkham/British Antarctic Survey

A digital model of a massive canal that carried meltwater away from ancient glaciers.

James Kirkham/British Antarctic Survey

What surprised the researchers most, they said, was how quickly these valleys formed. When the ice melted quickly, the water split the valleys in hundreds of years—lightning speed in geological terms.

“This is an exciting discovery,” said lead author James Kirkham, a researcher at BAS and the University of Cambridge. “We know that these amazing valleys were carved during the throes of dying ice sheets. Using a combination of the latest subsurface imaging techniques and a computer model, we’ve learned that tunnel valleys can quickly erode beneath the ice sheets that get extremely warm,”

Researchers believe that meltwater channels stabilize melting glaciers, and thus sea level rise, by helping prevent the collapse of ice sheets.

The new findings could complicate that picture. The authors added that the rapid rate at which the channels formed means that including them in current models could help improve the accuracy of predictions about the current melting of the ice sheet.

Today, only two major ice sheets remain: Greenland and Antarctica. melting rate Likely to increase as the climate warms.

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“The critical question now is whether this ‘extra’ flow of meltwater into the channels will cause the ice sheets to flow more quickly, or more slowly, into the sea,” Hogan said.