The Antarctic ice floe reached its lowest level in 44 years in February, at the end of southern summer, according to observations by a group of researchers published on Tuesday (19), when Antarctica appeared to be more resilient to climate change than the previous one. Arctic.
The natural cycle of the ice floe (the ice that floats in the ocean) is that it melts in summer and reforms in winter, with satellites since 1978 recording very accurately the areas covered in each season from year to year.
Melting has been rapid in Greenland and the Arctic, but conversely it has tended to increase slightly in Antarctica, despite significant annual and regional variations.
That year, the Antarctic ice floe collapsed and was measured at 1.9 million km2 on February 25, a record low since records began in 1978, according to a group of researchers mainly from Sun Yatsen University in Guangzhou , in an article published in the journal Advances in Atmospheric Sciences.
Five years after a previous record decline of just over 2 million km2 in 2017, the area covered by the ice floe has fallen below the 2 million km2 mark for the first time. This is 30% less than the average for the three decades between 1981 and 2010.
This study confirms observations by the US National Snow and Ice Data Center, which were announced a few weeks ago just before an unprecedented heat wave hit East Antarctica in March.
The disappearance of the ice floe west of the Amundsen Sea and east of the Ross Sea was complete by February 25, according to the authors of the study published on Tuesday. In general, the ice floe began retreating earlier in the year, beginning in early September, and compared to 2017, saw a late recovery in late February.
The melting is related to “thermodynamics”, i.e. the influence of temperatures, but also to the movement of the ice northwards to less polar latitudes and to a thinner ice layer on the coast of the Amundsen Sea.
Summer “anomalies” have been observed primarily in the western part of Antarctica, which is more vulnerable to climate change than the larger part of east Antarctica.
The melting ice floe does not affect sea levels as it is formed by freezing salt water. But reduced coverage is also a cause for concern.
When the white surface of the ice floe, which reflects solar energy, is replaced by the dark surface of the sea, “there is less heat reflection and more absorption,” explains Qinghua Yang, one of the coauthors, a professor at Sun Yatsen University .
“Which in turn melts more ice and creates more heat absorption, in a vicious cycle,” he describes.