Antarctica’s fringing waters have seen less ice than ever before, according to satellite observations taken over the past four decades.

The Southern Hemisphere’s summer of 2022 marked a new all-time low of 1.92m sq km on February 25, and the 2022 record had already been broken by February 12. By February 25, the new record low was 1.79m sq km, beating the previous record by an area double the size of Tasmania.

“By the end of January we could tell it was only a matter of time. It wasn’t even a close run thing,” says Dr Will Hobbs, an Antarctic sea ice expert at the University of Tasmania with the Australian Antarctic Program Partnership.

“We are seeing less ice everywhere. It’s a circumpolar event.”

Hobbs says large areas in the west of the continent had barely recovered from the previous year’s losses.

“Because sea ice is so reflective, it’s hard to melt from sunlight. But if you get open water behind it, that can melt the ice from underneath,” says Hobbs.

Polar scientists are concerned about the fate of Antarctica, which holds enough ice to raise sea levels by several meters if it melts. The disappearance of sea ice can have knock-on effects, such as weakening ice shelves, that can lead to more grounded ice entering the ocean.

The “doomsday glacier,” which is known to hold enough water to raise sea levels by half a meter, is a major concern for scientists.

“We don’t want to lose sea ice where there are these vulnerable ice shelves and, behind them, the ice sheets,” Prof Matt England, an oceanographer and climate scientist at the University of New South Wales, says.

“We are probably starting to see signs of significant warming and retreat of sea ice [in Antarctica]. To see it getting to these levels is definitely a concern because we have these potentially amplifying feedbacks.”

Data provided by scientists Dr Rob Massom, of the Australian Antarctic Division, and Dr Phil Reid, of the Bureau of Meteorology, shows two-thirds of the continent’s coastline was exposed to open water last month – well above the long-term average of about 50%.

“It’s not just the extent of the ice, but also the duration of the coverage,” Massom says. “If the sea ice is removed, you expose floating ice margins to waves that can flex them and increase the probability of those ice shelves calving. That then allows more grounded ice into the ocean.”

Scientists are scrambling for answers to understand the reasons behind the record losses.

Dr Ted Scambos is a sea ice expert at the University of Colorado Boulder who also works on Antarctic sea ice at the university’s National Snow and Ice Data Center – a world centre for monitoring ice at the poles.

He said the loss in sea ice in Antarctica “is causing the scientific community to wonder if there’s a process that’s related to global climate change”.

Antarctica is notoriously challenging to study, not just because of its remoteness, but in the challenges of gathering data around a continent exposed to huge variations in wind and storms from all directions.

Scambos said: “Since 2016 there has been a fairly sharp downturn [in sea ice] and especially with these back-to-back record years as well as many months being at near record lows, it’s causing the scientific community to wonder if there’s a process related to global climate change.”

He said while the most recent record could be attributed partly to a La Nina climate system that tends to deliver warmer winds to the continent, that didn’t explain the losses in other parts.

“We’re still trying to get to grips with what’s different now,” he says. “But it’s clear that reduced sea ice will have an impact. It’s going to have an impact on the continental ice because so much of the coast will be exposed.”

For many years Antarctica had been confounding climate models with sea ice slightly increasing on average. That was until a crash in 2016.

Dr Ariaan Purich, a climate scientist at Monash University, has analysed why the sea ice didn’t behave as many expected.

She said it was probably caused by changing winds and, counterintuitively, meltwater from the land entering the ocean that made it easier for ice to form.

“All the models project that as the climate warms, we expect to see [Antarctic sea ice] decline,” she says. “There’s widespread consensus on that. So this low sea ice is consistent with what the climate models show.”

Are the drops in sea ice and the back-to-back record lows a natural phenomenon in a continent hard to study? Or are these records another clear sign the climate crisis is changing the frozen continent?

“Antarctica might seem remote but changes around there can affect the global climate and the melting ice sheets affect coastal communities around the world,” says Purich.

“Everyone should be concerned about what’s happening in Antarctica.”

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