Thursday, 14 September 2023

Antarctic sea ice levels entering 'new low state', climate researchers say, with action urged on emissions.

Extract from ABC News

ABC News Homepage


ABC reporter Clancy Balen speaks to Dr Edward Doddridge about the deficit in sea ice levels.

Climate change is fundamentally changing Antarctic sea ice patterns in ways which may not be possible to reverse, Antarctic scientists have warned.

The dire message comes through new research which shows evidence of Antarctic sea ice levels being pushed into a new state of diminished ocean coverage — with more "record lows", like observed earlier this year, expected.

Report lead author Ariaan Purich, a climate scientist with Monash University's Securing Antarctica's Environmental Future team, said the results were cause for alarm.

"As part of this study, we were wanting to confirm this hypothesis… that we're in a new low state ," Dr Purich said.

"Sea ice isn't behaving in the way we previously expected [it] to."

A young man and women, both wearing glasses, stand with arms crossed
Researchers Edward Doddridge and Ariaan Purich.(Supplied: Harshula Jayasuriya)

Through analysing spatial data of sea ice coverage from 1978 to 2023, alongside ocean data records, she said it was evident ice patterns had changed — with warming ocean temperatures a key factor.

"It appears we're seeing the decline of sea ice long predicted by climate models," she said.

"We've burned fossil fuels, we've emitted greenhouse gases into the atmosphere, and we've caused this warming.

"We've disrupted that balance."

Graph depicting sea-ice melting
Sea ice surrounding Antarctica in 2023 is running at levels well below previous records.(Supplied: Bureau of Meteorology)

Loss of ice comes with risks to animals, rising sea levels

The formation of sea ice — which is ice that forms on top of the ocean — is cyclical, with winter a pivotal time for its formation.

At its peak, Antarctic sea ice levels can be equivalent to an area about two-and-a-half times the size of Australia.

Dr Purich said in July this year there was an area roughly the size of Western Australia missing.

"Even now, we've still got really large anomalies," she said.

"It's about 1.5 million square kilometres less sea ice than the maximum coverage usually seen in September."

Two tall penguins stand face to face with small chicks at their feet
Scientists say 10,000 emperor penguin chicks may have died in one part of Antarctica last year due to the premature breaking-up of sea ice.(Supplied: AAD/Garry Miller)

The kinds of devastating impacts this can have are already being seen, she said — with one "heartbreaking" example the deaths of thousands of emperor penguins last year, due to sea ice breaking up before the animals had matured enough to survive in the water.

But it's not just emperor penguins that rely on sea ice, Dr Purich said, with it also vital habitat for animals such as krill — which in turn impacts food chains, which has a roll on effect for fisheries.

A red ship moves through broken up sea ice.
The researchers say the "only thing we can do is reduce our greenhouse gas emissions".(Supplied: Australian Antarctic Division)

In addition to ecosystems, sea ice also plays a key role in helping regulate the earth's temperature, by reflecting the sun's heat back into space, and acts as a physical barrier for ice shelves, which then impacts on water sea levels.

"Sea ice is this remote thing," Dr Purich said. 

"[But] even though… it's far away, it's affecting our global climate, it's affecting our sea levels. So while it may not seem very tangible, it's really important."

Warming oceans a key factor as researchers call for climate action

Australian Antarctic Program Partnership physical oceanographer Edward Doddridge was a co-author on the report.

He said it was vital the link between warming ocean temperatures and the reported sea ice changes was not ignored.

'"The last time I spoke with the ABC, we were watching an immense change in the sea ice unfold," Dr Doddridge said.

"Winter time values were well below average in a way that we'd never observed in the satellite record.

"What's new now is that we've been able to link ocean warming to that change in sea ice."

Sea ice off Ross Island
Dr Purich says it "appears we're seeing the decline of sea ice long predicted by climate models".(Reuters: Deborah Zabarenko)

Dr Doddridge said while Antarctic research and funding fieldwork was vital, that alone wasn't enough to minimise the potential impacts of these changes.

"We know that our greenhouse gas emissions are warming the ocean around Antarctica, and that warming is pushing sea ice into a new low state.

"While research is extremely important… in order to counteract it, the only thing we can do is reduce our greenhouse gas emissions."

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