It’s remarkable that winter sea ice surrounding the Antarctic continent has increased
significantly in recent decades; a record level at 20.000.000 square km has been recorded.
This goes against the trend of overall ice loss and is in contrast to Arctic ice that has
decreased to a much greater extent (two thirds more,) than the increase in the South.
Sea ice in the Antarctic winter reached record highs between 2012 to 2014, though returned
to average levels in 2015. By contrast In the Arctic, both winter maximum and summer
minimum sea ice extent have declined sharply. Since the late 1970s the Arctic is said to have
lost an average of 20,800 square miles (53,900 km), of ice per year while the Antarctic gained
an average of 7,300 square miles (18,900 square km). The cause for this is, I understand,
uncertain. A possible explanation is that there is a low-pressure system over
the Amundsen Sea (on the west coast of Antarctica). This changes wind patterns,
circulating warm air over the peninsula (with consequent loss in sea ice) and sweeping cold air
over the Antarctic continent towards the Ross Sea. Other suggestions include melting ice
on the edges of the continent. This is at just above freezing, and can easily refreeze into sea ice
I understand. Changes in water circulation bringing colder waters to the surface has also been
suggested, also snow which pushes thin ice below the water surface and allows seepage of sea water
into the surface snow with subsequent freezing.
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