(Washington) The Antarctic ice shelf has reached its maximum surface area for the year, and it has never been so small since scientific surveys began, the American reference observatory announced on Monday.
The Antarctic ice shelf melts in summer and recovers in winter. The latter is currently ending in the Southern Hemisphere.
On September 10, “the Antarctic sea ice reached a maximum annual extent of 16.96 million km2 “, wrote the National Snow and Ice Data Center (NSIDC). “This is the lowest maximum for sea ice in records from 1979 to 2023, by far. »
The maximum extent reached this year is 1.03 million km2 lower than the previous record, almost twice the surface area of France.
In February, in the middle of the austral summer, the Antarctic sea ice reached a low, with a minimum extent of 1.79 million square kilometers – a melting record – according to the NSIDC.
Subsequently, the sea ice reformed at an unusually slow rate, despite the arrival of winter.
In the Arctic, where summer is ending, sea ice has also reached its lowest extent for the year, at 4.23 million km2, announced the NSIDC. This is the sixth lowest in 45 years of data.
“Sharp turn”
For several decades, the Antarctic sea ice remained stable, or even expanded slightly.
But “since August 2016, the trend concerning the extent of the Antarctic sea ice has taken a sharp downward turn, during almost every month” of the year, explains the NSIDC.
The explanation is a subject of debate among scientists, who are reluctant to establish a formal link with global warming, as climate models have struggled in the past to predict changes in the Antarctic sea ice.
But this trend since 2016 now appears “linked to the warming of the upper layer of the ocean”, writes the American observatory. “There is concern that this could be the start of a long-term trend of decline in Antarctic sea ice as oceans warm globally. »
The melting of the sea ice does not have an immediate impact on sea levels, because it is formed by freezing the salt water already present in the ocean.
But the white ice reflects the Sun’s rays more than the darker ocean, and its loss thus accentuates global warming.
The loss of sea ice also further exposes the coasts of Antarctica to waves, which could destabilize the ice cap, which is made up of fresh water. Its melting would cause a catastrophic rise in ocean levels.