Antarctic ice floes reached a 44-year low in February, at the end of the Australian summer, according to observations by a group of researchers published Tuesday (19), when Antarctica It looks like he’s resisting better weather changes from the North Pole.
The natural cycle of drift ice (ice that floats in the ocean) is that it melts in the summer and forms again in the winter, with satellites meticulously recording since 1978 the areas it covers in each season, year to year.
Melt was rapid in Greenland and the Arctic, but, on the contrary, in Antarctica, it tended to increase slightly, despite significant annual and regional differences.
This year, the Antarctic ice floe has fallen sharply and measured 1.9 million km.two On February 25, a record low since records began in 1978, a group of researchers primarily from Sun Yat-sen University in Guangzhou, reported in Article published in Advances in Atmospheric Sciences.
Five years after the previous record drop of more than 2 million kmtwo In 2017, the area covered by the ice floe decreased to less than 2 million kmtwo for the first time. That’s 30% below the average over the three decades between 1981 and 2010.
This study confirms observations of the US National Snow and Ice Data Center that it announced a few weeks ago, before the arrival of an unprecedented heat wave in East Antarctica in March.
According to the authors of the study published on Tuesday, in the western Amundsen Sea and eastern Ross Sea, the disappearance of the ice floe was completed on February 25. In general, the raft began to decline earlier in the year, starting in early September, and compared to 2017, recorded a late recovery, at the end of February.
Melting is associated with “thermodynamic”, that is, the effect of temperatures, but also with the movement of ice northward to lower polar latitudes and a thinner layer of ice on the coast of the Amundsen Sea.
Summer “deviations” are observed mostly in the western part of Antarctica, which is more vulnerable to climate change than the larger area in East Antarctica.
Melting of ice does not affect sea level, because it is formed by the freezing of salt water. But the lower coverage is also a cause for concern.
When the white surface of the raft, which reflects the sun’s energy, is replaced by the dark surface of the sea, “there is less heat reflection and greater absorption,” explains Chenghua Yang, one of the co-authors, a Sun professor. Yat-sen University.
“Which in turn melts more ice and produces more heat absorption, in a vicious cycle,” he describes.
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