Record low sea-ice levels around Antarctica ‘likely due to climate change’

Record-breaking low levels of sea ice around Antarctica in 2023 may have been influenced by climate change, scientists have said.

Researchers at the the British Antarctic Survey (BAS) analysed data from 18 different climate models.

They found Antarctica’s historically low sea-ice levels were a one-in-2,000-year event without climate change but four times more likely under its effects.

Rachel Diamond, lead author on the paper published in journal Geophysical Research Letters, said: “This is the first time this large set of climate models has been used to find out how unlikely 2023’s low sea ice actually was.

“We only have 45 years of satellite measurements of sea ice, which makes it extremely difficult to evaluate changes in sea-ice extent.

“This is where climate models come into their own.

“According to the models, the record-breaking minimum sea-ice extent would be a one-in-a-2,000-year event without climate change.

“This tells us that the event was very extreme – anything less than one-in-100 is considered exceptionally unlikely.”

In 2023, the Antarctic sea ice reached record-low levels, with over 2 million square kilometres less ice than usual during winter – about 10 times the size of the UK.

Until 2015, Antarctica’s winter sea ice had been growing in size since satellite records began in 1978.

Antarctica’s vast expanse of sea ice regulates Earth’s temperature, as the white surface reflects the Sun’s heat back into the atmosphere and cools the water beneath it.

Without it, the planet would be a much hotter place.

For the study, the team used the latest climate dataset called CMIP6 to investigate whether warming played a role in Antarctica’s sea levels.

Caroline Holmes, a co-author on the study, said: “Strong climate change – ie, the temperature changes we’re already seeing, and those expected if emissions continue to rise rapidly – in the models makes it four times more likely that we see such a big decline in sea-ice extent.

“This suggests that 2023’s extreme low was made more likely by climate change.”

The BAS scientists also looked at how well sea ice is likely to recover and found that it would remain low, even after 20 years.

This would impact penguins, whales and other animals that rely on the ice for their habitat, the researchers said.

Louise Sime, a co-author on the study, said: “The impacts of Antarctic sea ice staying low for over 20 years would be profound, including on local and global weather and on unique Southern Ocean ecosystems – including whales and penguins.”