Record-low indicators of the sea ice area in Antarctica were recorded by Russian scientists. According to the Arctic and Antarctic Research Institute (AARI), there has not been such an active melting in the last 44 years.
The specialists at the Center for Ice Hydrometeorological Information (CIHI) of AARI note that the area of Antarctic sea ice at the end of February 2023 amounted to about 1.8 million km2. This is the lowest indicator in the entire period of regular observations of the ice situation, which have been conducted in Antarctica since 1979. The ice remaining after the summer melting was preserved mainly in the Weddell and Amundsen Seas, in the rest of the seas it remained only along the coast.
The minimum ice cover at the end of the summer season is observed in the Southern Ocean for the second year in a row. In February 2022, the area of sea ice at this time was 1.92 million km2.
The CIHI specialists track the amount of ice from satellite images all year round and map the ice situation in all Antarctic seas. When winter ends in September in the Southern Hemisphere, the area of sea ice reaches its maximum. In 2022, in particular, in mid-September, this figure amounted to almost 18.2 million km2.
During December and February, there is a summer melting of sea ice around Antarctica. Usually its area is reduced to 3 million km2. But in 2023, for several reasons, the temperature in the region was higher than usual. In combination with strong winds, this contributed to the formation of huge areas freed from ice.
In the summer season of 2022-2023, the minimum ice cover of the Southern Ocean over the past seven years was also observed – 2.23 million km2. At the same time, the maximum area of sea ice in the Antarctic winter turned out to be more than 20 million km2, which is slightly higher than the norm of 18-19 million km2. During the Antarctic summer, about 18 million km2 of sea ice melted.
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The scientists also drew attention to the reduction of the area of the ice fringe, which is the only source of replenishment of the rapidly thinning outer belt of drifting ice during circumpolar transfer. It amounted to only 489 thousand km2, and this is the minimum value in seven years.
The AARI scientists have identified several reasons for the record low rates of ice cover. The main one is the Antarctic Circumpolar Current, or, as it is also called, the West Wind Drift, in the Southern Ocean. It separates warm subtropical water in the north from cold water in the south. As the climate changes, the prevailing westerly winds intensify. Despite their insignificant influence on ocean currents, they strengthen circular return currents, which provokes the influx of warm waters into drifting ice.
Separately, we can note the degradation of the ice massif in the Pacific sector, where subglacial heating by underwater volcanoes is observed. The volcanic belt of Antarctica can be traced along the western coast of the mainland. The largest glacial-volcanic province in the world is located here, the thinned lithosphere allows magma to rise close to the surface. When activated, mass eruptions contribute to an increase in the rate of melting of sea ice in this area of Antarctica.