Winter sea ice in the Antarctic hits record low: Data
Antarctic sea ice reached its lowest ever recorded annual maximum extent, according to the National Snow and Ice Data Center. Scientists believe the decline is likely linked to warming in the uppermost ocean layer. The maximum extent of 16.96 million square kilometres was also one of the earliest on record, reaching it 13 days earlier than the 1981 to 2010 median date of 23 September. The long-term downward trend in Antarctic sea ice has been a topic of debate, with evidence of a climate crisis link emerging recently.
Sea ice in the Antarctic reached its annual maximum extent of 16.96 million square kilometers on September 10 — the lowest ever recorded — preliminary figures released by the National Snow and Ice Data Center (NSIDC) at the University of Colorado Boulder showed on Monday, with scientists warning that the decline is likely “linked to warming in the uppermost ocean layer”.
The sea ice extent was 1.03 million square kilometers smaller than the previous record set in 1986.
The record low comes at a time when the sea ice that packs the ocean around Antarctica typically reaches its largest area in the winter months, which is the northern hemisphere summer.
“This is the lowest sea ice maximum in the 1979 to 2023 sea ice record by a wide margin,” said NSIDC.
The maximum extent is also one of the earliest on record, having reached it 13 days earlier than the 1981 to 2010 median date of September 23, the US government supported program said.
While natural factors such as wind and temperature play a role in variations in the ice extent, the long-term downward trend has been a topic of debate for some time with evidence of a climate crisis link emerging recently.
“Antarctic sea ice shows substantial variability year to year. Nevertheless, what is happening this year is well outside the bounds of anything seen before. We don’t yet know if it is due to climate change, but that is a likely cause,” Edward Doddridge, physical oceanographer, University of Tasmania, told HT in an email interview in July.
According to NSIDC, every decade since 1979 — when record-keeping began — sea ice in the Antarctic is dropping 0.1% relative to the 1981 to 2010 average.
While this is not a significant trend, the movement has been steadily downward since 2016, which NSIDC attributed to a series of storms. “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, and warm water mixing in the Southern Ocean polar layer could continue,” NSIDC said.
Monday’s figures were released after scientists said in July that a five-sigma event was unfolding in the continent.
“We would expect to see a winter like this about once every 7.5 million years,” Doddridge had told ABC News at the time.
A five-sigma event indicates a statistical anomaly five standard deviations away from the mean, making it an exceptionally rare event with a very low probability of happening by chance.
Scientists observed that the ice was struggling to grow back from its February nadir, in a stark deviation from usual patterns.
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. And from September 10 when it stretched to its maximum, the sea ice began declining again.
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, NSIDC said. It represents the sixth lowest minimum in 45 years of record-keeping.
If sea-ice coverage that is dramatically lower than usual continues, more of the coastline will be exposed to ocean waves, the effects of which are not yet clear, NSIDC noted. The impacts could include an acceleration in the warming of sea which then gets carried around the rest of the world, affecting weather patterns and ecosystems.
