The Getz glaciers of West Antarctica flow faster


Wherever you look in West Antarctica right now, the message is the same: its glaciers that end in the sea are melting with warm seawater.

Scientists have just observed in detail the ice currents that flow into the ocean along a 1,000-kilometer stretch of coastline known as the Getz region.

It incorporates 14 glaciers, and all of them have accelerated.

Since 1994, they have lost 315 gigatons of ice, which is equivalent to 126 million Olympic pools of water.

If you put this in the context of the Antarctic continent’s contribution to global sea level rise over the same period, Getz accounts for just over 10% of the total, just under a millimeter.

“This is the first time that someone has done a really detailed study of this area of ​​West Antarctica. It is very inaccessible for people to go and do field work because it is very mountainous; most of it has never been stepped on by humans.” added. explained Heather Selley, a glaciologist at the Nerc Center for Polar Observation and Modeling at the University of Leeds, UK.

“But it is really important that we understand what is happening there, recognize that its glaciers are accelerating and why,” he told BBC News.

Selley and his colleagues examined two and a half decades of satellite radar data on the speed and thickness of the ice. To this analysis, they added information on the properties of the ocean immediately off the Getz coast, along with the results of a model that put the local climate in context during the period.

Glacier speeds

The findings, published in the journal Nature Communications, reveal an unmistakable linear trend.

On average, the speed of the 14 glaciers in the region increased by almost a quarter between 1994 and 2018, and the speed of the three central glaciers increased by more than 40%.

A particular ice stream was found to flow 391 m / yr faster in 2018 than in 1994, a 59% increase in just two and a half decades.

The probable cause, once again, is what the researchers call “oceanic forcing.” Relatively warm deep ocean water is creeping under the floating fronts of glaciers and melting them from below.

Pierre Dutrieux, co-author of the British Antarctic Survey study, said: “We know that warmer ocean waters are eroding many of the glaciers in West Antarctica, and these new observations demonstrate the impact this is having on the Getz region.”

“This new data will provide a new perspective on the processes that are taking place so that we can predict future changes with more certainty.”

Where a line of glaciers pushes out to sea, their floating fronts often come together to form a single, continuous shelf known as an ice shelf. It is interesting to note that in the case of Getz, this platform receives some stability by pressing against eight islands and various shallow points on the seabed.

And yet, even with this built-in stability, the glaciers feeding behind are melting and accelerating.

Co-author Anna Hogg, also from Leeds, is an expert in satellite remote sensing of the polar regions.

She told BBC News: “We now have observations around the entire margins of the Greenland and Antarctic ice sheets in a way we’ve never had before. We can map out really detailed, localized patterns of change.

“We are understanding how ocean water moves under the ice shelf, how and where it enters that cavity under the ice shelf, so that we can really link the physical process of ocean force to the signal that we see in the satellite data.. “

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