2023-10-25 08:29:13
A setting frozen in time: scientists have detected a vast landscape of green hills and valleys, hidden for millions of years under the ice of Antarctica, according to a study published Tuesday.
This landscape larger than Belgium would have remained intact for potentially more than 34 million years, but could be freed by melting ice due to global warming, warn the British and American researchers behind the discovery. “This is an undiscovered landscape that no one has ever laid eyes on,” Stewart Jamieson of the British University of Durham, lead author of the study published in Nature Communications, told AFP.
The researchers did not need new data to detect it, but simply used a new approach to this terra incognita, located under the East Antarctic ice sheet, much less known than the surface of Mars.
To see what is hidden underneath, it was necessary to send radio waves into the ice, flown over by plane, then analyze the echoes, a technique called radio-ultrasound survey. But carrying out this operation on a continent-wide scale Antarctica – larger than Europe – would pose a significant challenge. The researchers therefore used existing satellite images of the surface to “map the valleys and ridges” more than two kilometers deep, explained Stewart Jamieson.
By combining these data with those of the radio-ultrasound survey, the image of a landscape carved by a river emerged, composed of deep valleys and hills with steep peaks, similar to those currently found on the surface of the Earth. “It was as if we were looking out of the window of an airplane and seeing a mountainous region below,” deciphers the glaciologist, who compares this landscape to the region of Snowdonia, in north Wales. .
Also read Antarctica: We have “lost control” of the melting of the ice shelves
AFP
Climate threat
This 32,000 square kilometer expanse was once home to forests and probably animals. Before the ice covers it to “freeze it in time”. It is difficult to determine precisely when the landscape was last exposed to the Sun, but estimates suggest it was at least 14 million years ago. Professor Jamieson’s “hunch” is that this happened more than 34 million years ago, when Antarctica began to freeze over.
Researchers previously found a city-sized lake beneath Antarctica’s ice, and the study’s authors hope to unearth even more landscapes. Except that global warming could threaten their latest discovery. The landscape is fortunately miles from the edge of the ice cap, which should protect it from future exposure to light. Another reassuring parameter: this hidden world was not affected by the retreat of ice during ancient periods of warming – such as the Pliocene period, 3 to 4.5 million years ago.
But we still do not know what the climatic “tipping point” of an “uncontrolled reaction” of ice melting will be, underlines Professor Jamieson. On Monday, a study warned that the melting of the ice sheet in neighboring West Antarctica was likely to accelerate significantly in coming decades. And this even if the world respected its commitments to limit global warming.
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