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Unusual winds could result in the destruction of the fourth largest ice floe in Antarctica, the researchers warned.
In an article published in the journal Geophysical Research Letters, a team led by Rajashree Tri Datta of the University of Maryland, revealed that the Larsen C ice sheet had experienced an unusual spike in late summer and early fall, the melting of surface areas from 2015 to 2017.
The discovery raises fears that the plateau, part of the Antarctic Peninsula, the northernmost part of the continent, may follow the fate of two other large ice platforms, Larsen A and B.
Snow and ice melting at the surface of the ground caused the breakup of Larsen A in 1995. In 2003, Larsen B calved a section of about 3,000 square kilometers.
The Antarctic Peninsula is particularly vulnerable to changes in global conditions and the assessment of the stability of Larsen C – which is south of where Larsen B – Datta and his colleagues were studying. data covering the years 1982 to 2017.
They found that over the last two years, a particular type of wind – called foehn wind – had its origin in the central high mountain range of the peninsula and was sending warm, dry air downward, near the surface.
Increased foehn activity resulted in an above-average degree of melt, which began to reshape the Larsen C snowpack, an evolution that, if continued, could compromise shelf integrity.
"Three years do not make a trend," says Datta, "but it's quite unusual that we are witnessing stronger foehn winds and the melting associated with late summer and early summer." 39; fall.
Data from previous years show that winds have decreased much earlier in the season and melting speeds have decreased. Fresh falls then reconstitute the snowpack.
However, as it has not happened for three consecutive years, the topology of the shelf is changing, a situation that could have consequences increasingly unfavorable.
"With increased densification, the ice is entering the next warm season with a very different structure," says Datta.
"Our modeling results show that with less free space to filter surface water, runoff increases year by year. Dominant theory suggests that increased densification has led to the rupture of the Larsen A and B shelves. "
Because the ice floes, if the worst happens at the worst and the Larsen C breaks and breaks, it will not lead to an increase in the sea level. However, the image is not so simple.
"The pack ice is preparing for the flow of glaciers that feed it," warns Datta.
"So, if Larsen C disappears, some of these glaciers will be free to speed up and melt, which will raise sea levels globally."
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