WASHINGTON, Sept 26, 2023 (BSS/AFP) - The sea ice around Antarctica likely
had a record low surface area when it was at its maximum size this winter, a
preliminary US analysis of satellite data showed Monday.

As the southern hemisphere transitions into spring, the US National Snow and
Ice Data Center (NSIDC) said in a statement that Antarctic sea ice had only
reached a maximum size of 16.96 million square kilometers (6.55 million
square miles) this year, on September 10.

The ice pack typically reaches its largest size during the colder winter
months, so the September 10 reading will likely remain this year's maximum.

"This is the lowest sea ice maximum in the 1979 to 2023 sea ice record by a
wide margin," said the NSIDC, a government-supported program at the
University of Colorado at Boulder.

At its high-point this year, the sea ice was 1.03 million square kilometers
smaller than the previous record, roughly the size of Texas and California
combined.

"It's a record-smashing sea ice low in the Antarctic," said NSIDC scientist
Walt Meier.

He added that the growth in sea ice appeared "low around nearly the whole
continent as opposed to any one region."

In February, at the height of the austral summer, the Antarctic sea ice pack
had reached a minimum extent of 1.79 million square kilometers, also a
record, according to the NSIDC.

The ice pack then grew back at an unusually slow pace, despite the onset of
winter.

Meanwhile at the other end of the globe, where summer is drawing to a close,
Arctic sea ice reached a low of 4.23 million square kilometers, the NSIDC
said. It represents the sixth lowest minimum in 45 years of recordkeeping.

- Warming oceans -

For several decades, the Antarctic sea ice pack had remained stable, even
expanding slightly.

But "since August 2016, the Antarctic sea ice extent trend took a sharp
downturn across nearly all months" the NSIDC said.

There is debate among scientists over the cause of the shift, with some
reluctant to establish a formal link with global warming. Climate models have
struggled in the past to predict changes in the Antarctic ice pack.

The downward trend is "now thought to be linked to warming in the uppermost
ocean layer," the NSIDC said.

"There is some concern that this may be the beginning of a long-term trend of
decline for Antarctic sea ice, since oceans are warming globally."

Melting pack ice has no immediate impact on sea levels, as it forms by
freezing salt water already in the ocean.

But the white ice reflects more of the Sun's rays than darker ocean water, so
its loss accentuates global warming.

The loss of pack ice also exposes Antarctica's coastline to greater wave
action, which could destabilize the freshwater ice cap and endanger coastal
habitats. The melting land ice would cause a catastrophic rise in sea levels.

However the NSIDC notes a possibility that waves impacting the ice sheet may
increase "accumulation near the coast, offsetting in part the threat of
rising sea level."