The Antarctic ice floe reached its lowest level in 44 years in February, at the end of the austral summer, according to observations by a group of researchers published on Tuesday (19), when Antarctica seemed to resist climate change better than the previous one. Arctic.
The natural cycle of the ice floe (the ice that floats in the ocean) is that it melts in the summer and forms again in the winter, with satellites recording very accurately since 1978 the areas covered in each season, from year to year.
Melting has been rapid in Greenland and the Arctic, but conversely, in Antarctica, it has tended to increase modestly, despite significant annual and regional variations.
This year, the Antarctic ice floe plummeted and was measured at 1.9 million km.two on February 25, a record low since records began in 1978, reports a group of researchers primarily from Sun Yat-sen University in Guangzhou, in a paper published in the journal Advances in Atmospheric Sciences.
Five years after a previous record drop of just over 2 million kmtwo in 2017, the area covered by the ice floe dropped below the 2 million km marktwo for the first time. That’s 30% less than the average over the three decades between 1981 and 2010.
This study confirms the observations of the US National Snow and Ice Data Center announced a few weeks ago, just 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 west of the Amundsen Sea and east of the Ross Sea, the disappearance of the ice floe was complete on February 25. More generally, the floe started to retreat earlier in the year, starting in early September, and compared to 2017, it recorded a late recovery, at the end of February.
The melting is linked to “thermodynamics”, i.e. the influence of temperatures, but also to the movement of ice northwards to less polar latitudes and to a thinner layer of ice on the coast of the Amundsen Sea.
Summer “anomalies” were mostly observed in the western part of Antarctica, which is more vulnerable to climate change than the greater area of East Antarctica.
The melting ice floe has no impact on sea level, because it is formed by the freezing of salt water. But less coverage is also a cause for concern.
When the white surface of the floe, which reflects the sun’s energy, is replaced by the dark surface of the sea, “there is less heat reflection and more absorption,” explains Qinghua Yang, one of the co-authors, a professor at Sun Yat-sen University.
“Which, in turn, melts more ice and produces more heat absorption, in a vicious circle,” he describes.