"After two seasons of record-breaking lows, Antarctica’s sea ice remains in
dramatic decline, tracking well below any winter maximum levels observed since
satellite monitoring began during the late 1970s.
A layer of frozen seawater that surrounds the Antarctic continent, sea ice
cycles from maximum coverage in September to a minimum in February. The summer
minimum has also continued to diminish, with three record low summers in the
past seven years.
Some scientists have suggested this year could mark a regime shift for
Antarctic sea ice. The consequences could be far-reaching for Earth’s climate,
because sea ice keeps the planet cooler by reflecting solar energy back into
the atmosphere and insulating the ocean. Its formation also generates cold,
salty water masses that drive global ocean currents.
The annual freeze-thaw cycle of Antarctic sea ice is one of Earth’s largest
seasonal changes, but is a major challenge for climate models to predict
Since the 1970s, satellites have been tracking a quantity known as “sea ice
extent”, which is the total surface area where at least 15% is covered by sea
This September, it reached a satellite-era record low for this time of year.
The previous year, after tracking much lower than the median all winter,
Antarctic sea ice extent made a late rally and was 18.3 million square
kilometres at its maximum by September 2022, around 2% below the 1981-2010
Although 2% might not sound like much, the following summer biologists reported
devastating effects on Emperor penguins. No chicks survived in four out of five
breeding sites in one region of sea ice loss.
In 2023, Antarctic sea ice extent started the winter even lower than in 2022,
and by the end of July was almost 13% below the 1981-2010 median for that time
of year. It reached its maximum extent on September 7, at just under 17 million
square kilometres, which is nearly 9% below the 1981-2010 median."
*** Xanni ***
Chief Scientist, Xanadu
Partner, Glass Wings
Manager, Serious Cybernetics