Antarctica’s sea ice has reached its annual maximum – a record low – and has started to recede as temperatures warm during spring.
That maximum area of sea ice that formed around Antarctica was recorded on September 10 – 16.956 million km2 – about 1.289 million km2 less than 2022’s previous record low.
For comparison, that’s an area larger than the size of the Northern Territory missing in a single year.
Compare this year’s record low to the peak from 2021, the area bulges to 1.884 million km2 – more than the size of Queensland.
That failure to form is troubling many scientists who have warned of the impacts record levels of human greenhouse gas emissions are having on atmospheric and ocean warming.
“We have never seen a year like this,” says Dr Edward Doddridge, a physical oceanographer at the University of Tasmania.
“It feels like a step change. The ice has been below average since 2016 when it dropped really suddenly over 2015-2016, but this year it was like another jump down… there’s a huge gap between anything we have seen before.”
In conjunction with fellow Antarctic researcher Dr Ariaan Purich, Doddridge earlier this month described a ‘regime shift’ driven by atmospheric and ocean conditions surrounding Antarctica. They connect subsurface ocean warming to shifts in sea ice formation.
Doddridge points to the lack of regional compensation for sea ice in Antarctica that had been previously witnessed – if one area was low in sea ice, another would be higher.
“It’s not just that the ice gets blown out of one region and hangs around in another, it’s just not forming overall,” he says.
As Doddridge and Purich’s research is only weeks old, other Antarctic scientists are yet to fall in behind their hypothesis.
Regardless of the drivers behind the unprecedented reduction in sea ice, the potential consequences are well established. In 2022, several emperor penguin colonies experienced a catastrophic breeding failure due to sea ice melting before chicks were equipped to survive the water below. Krill – a vital food source for many marine species – require sea ice to breed and feed.
Doddridge is concerned that, while it’s too early to say 2023 marks another sea ice regime change, it could eventually mark the start of a dangerous new state for Antarctica.
“We won’t be able to say that until we’ve got several years of data. It could just be a blip – I don’t think so – but that’s going to take several more years of observations before we can start making statements like that.”
Recently, an Australian Senate inquiry was convened to look at the decision by the Australian Antarctic Division to cut its operating budget by a sixth. In his submission Doddridge described the prospect of cuts during a year of record sea ice decline as “devastating,” and he called for dedicated fieldwork to understand the shifts underway on the continent.
“In order to be able to understand what’s going on with the sea ice, we need people down there measuring how thick it is, the snow on top, and the ocean underneath.”
The Australian Meteorological and Oceanographic Society – the professional association of the nation’s climate scientists – echoed that view, suggesting compromises to Antarctic research would diminish Australia’s reputation.
“Australia’s international standing as leader in Antarctic science will be negatively impacted if its Antarctica and Southern Ocean science capabilities are reduced,” AMOS says in its submission. “The only gateway to Antarctica for Australian and many international scientists is through the Antarctic Division. Reducing field work capabilities over the near term will mean a shift away from Australia for these logistical capabilities. This is likely to limit future opportunities for collaboration and innovation.”