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Wherever you look in West Antarctica right now, the message is the same: its marine terminating glaciers are melted by warm seawater.
Scientists have just taken a detailed look at the streams of ice flowing into the ocean along a 1,000 km stretch of coastline known as the Getz region.
It incorporates 14 glaciers – and they’ve all accelerated.
Since 1994, they have lost 315 gigatons of ice – the equivalent of 126 million Olympic swimming pools of water.
If you put this in the context of the contribution of the Antarctic continent to global sea level rise over the same period, Getz is just over 10% of the total – just under a millimeter.
“This is the first time that anyone has done a really detailed study of this region of West Antarctica. It is very inaccessible for people to go and do field work because it is so mountainous; most of between them have never been trampled by humans ”. explained Heather Selley, glaciologist at the Nerc Center for Polar Observation and Modeling at the University of Leeds, UK.
“But it’s really important that we understand what’s going on there – to recognize that its glaciers are accelerating and why,” she told BBC News.
Selley and his colleagues looked at two and a half decades of satellite radar data on ice speed and thickness. To that analysis, they added information on ocean properties immediately off Getz – as well as results from a model that puts the local climate into context over the period.
The results, published in the journal Nature Communications, reveal an unambiguous linear trend.
On average, the speed of the region’s 14 glaciers increased by almost a quarter between 1994 and 2018, with the speed of three central glaciers increasing by more than 40%.
One ice current in particular flowed 391 m / year faster in 2018 than in 1994 – a 59% increase in just two and a half decades.
The likely cause, again, is what researchers call “ocean forcing.” Relatively warm, deep ocean water penetrates beneath the floating fronts of glaciers and melts them from below.
Pierre Dutrieux, co-author of the study at the British Antarctic Survey, said: “We know that warmer ocean waters are eroding many glaciers in West Antarctica, and these new observations demonstrate the impact this has on the sea. Getz region.
“These new data will provide a new perspective on ongoing processes so that we can predict future changes with more certainty.”
Where a line of glaciers pushes into the sea, their floating fronts often come together to form a single, continuous platform called an ice shelf. Interestingly, in Getz’s case, this platform receives some stability by pressing against eight islands and a number of shallow points on the seabed.
And yet, even with this inherent stability, the glaciers that feed behind it 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 across all the margins of the Greenland and Antarctic ice caps in a way we’ve never had before. We are able to map patterns of change. very detailed and localized.
“We understand how ocean water moves under the ice shelf – how and where it enters this cavity under the shelf, so that we can really relate the physical process of forcing the oceans to the signal. that we see in satellite data. “
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