Global warming threatens the support of the Antarctic glacier

(Paris) Global warming could endanger more than half of the major ice barriers (sea extensions of a terrestrial glacier) supporting Antarctic glaciers as warnings about melting increase. accelerated glacial zones.

Posted August 26, 2020 at 11:47 AM

France Media Agency

Using artificial intelligence systems to analyze satellite surveys, the researchers mapped fissures cracking these ice barriers, which act as pillars or flying buttresses that contribute to the stability of the ice sheet, which rests on Earth, their study explains Thursday in the journal Nature has been published.

They then calculated the vulnerability of these crevices when they were filled upstream with water from the melting ice, and concluded that in such a case, between 50 and 70% of them could break. In fact, water is denser and thus heavier in equal volume than ice and exerts different pressures on it.

However, if an ice barrier collapses, the glaciers it helps hold can in turn flow into the ocean, causing sea levels to rise dangerously.

Most of the barriers are currently stable and frozen all year round, but these kinds of phenomena have already been observed. Parts of the Larsen Barrier, at the tip of the Antarctic Peninsula, disintegrated within weeks in 1995 and 2002.

However, the authors note that predictions of the melting ice in Antarctica suggest that the accumulation of water from this phenomenon “could extend to many vulnerable areas in warming scenarios. [climatique] future “.

In particular, they point to the glaciers of Pine Island and Thwaites in western Antarctica, which have a combined area larger than Germany’s.

The warming of the ocean temperature is also contributing to weakening the great ice barriers from below.

“The barriers are the weak point where the atmosphere, ice and ocean interact. When they fill with meltwater, things can move very quickly and there can be major consequences for sea levels, ”said study co-author Jonathan Kingslake, a glaciologist at Columbia University in a statement. .

A team of British researchers also estimated in a study currently in pre-publication – and therefore not yet reviewed and approved by other specialists – that the Earth lost 28,000 billion tons (gigatons) of ice between 1994 and 2017. Or less 0.1% of the total ice, but enough to raise the sea level by 35 mm.

According to climate experts from the UN (IPCC), the sea level has already risen by 15 cm in the 20th century. Result: By 2050, more than a billion people will live in coastal areas that are particularly vulnerable to flooding or extreme weather events.

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