Antarctica records its lowest levels of ice

The Antarctic sea ice, seen from the Xuelong II ship on January 30, 2022. / YINGQI LIANG

The surface of the frozen sea at the South Pole is reduced by 170,000 km2, a "historical minimum", according to research carried out in the austral summer

Domenico Chiappe

Until now, global warming affected the extent of the Arctic ice, but in the southern hemisphere, Antarctica maintained its mass of frozen water, and even registered a very slight upward trend in recent years. But this southern summer the South Pole lost sea ice and reduced its levels to the lowest levels recorded since satellites measured this vertex of the planet in 1978, warned scientists from the universities of Sun Yat-sen (China) and Albany (USA). USA).

This "record low" quantifies the extent of permanent ice at 1.9 million km2 at the end of February. They are 170,000 km2 less than the lowest level previously recorded, in 2017, when the ice also receded, indicates the article 'An unprecedented record in the reduction of the extent of frozen sea in Antarctica during the southern summer of 2022', published in the journal 'Advances in Atmospheric Sciences'.

In addition to measuring sea ice, the researchers looked for reasons for the variability in its mass. Their findings indicate that when spring begins, physical phenomena bring more heat to the poles, through the Bellingshausen, Amundsen and Ross seas, which was one of the areas where the ice turned to water to a greater extent. In another region in the far south of the world, the Weddell Sea, the frozen layer was thinning due to 'surface heat fluxes'. All of this "summer sea ice melting could be related to the record temperatures of the Southern Ocean in 2021," says the paper's lead author, Jinfei Wang, along with co-signers.

The study also demonstrates a relationship between the whiteness of the snow at the South Pole and the temperature that feeds a "vicious circle", according to the scientists. The whiter, the more it reflects the radiation, but as it thaws, that effect is lost and the heat multiplies. Lastly, the La Niña phenomenon, with its powerful winds that move warm water from the oceanic surface of the tropics towards the extremes, influences this loss of glacial surface. Scientists' alarm is greater when compared to the average of the previous three decades, from 1981 to 2010, since the decrease in the extent of sea ice in Antarctica reaches 30%.

Source link