Antarctic sea ice loss causes rapid ocean layer change

Summarised from 2 outlets · Updated 28 Oct, 18:15 · Archive

A crucial ocean layer has become saltier and denser since 2016 as Antarctic sea ice melts at record rates.

A vast ocean layer in the southern hemisphere has undergone a surprising and rapid shift since 2016, becoming saltier and denser in conjunction with record low Antarctic sea ice, according to a study published in Nature Climate Change. Antarctic Intermediate Water, which typically sits 500 to 1500 metres below the surface and is fed by melting Antarctic sea ice during summer, had remained stable from 1995 to 2015. However, the layer has abruptly changed from 2016 to 2024.

The water acts as a 'climate buffer', absorbing and redistributing excess heat and a large share of human carbon dioxide emissions. University of Melbourne associate professor Bishakhdatta Gayen, the study lead, described the change as surprising and rapid. 'Since we have records in oceanography, we have never seen this water alter,' he said. 'It's a big signal, the ocean is altering and it looks like the ocean is changing even faster than we thought.'

The researchers analysed data from 4000 robotic floats, satellite information and atmospheric data. The last comparable shift in the layer occurred around 130,000 years ago at the end of the previous interglacial period, but that transition took thousands of years. According to the study authors, a weaker layer could push more excess heat deeper into the ocean, suggesting that climate models may have underestimated deep-ocean warming and regional sea-level rises.

How it is being reported

• 'Never seen': sea ice loss triggers big ocean changeA study has uncovered a surprising and rapid shift in an important ocean layer which is fed by melted sea ice from Antarctica.Perth Now · 28 Oct, 18:02
• 'Never seen': sea ice loss triggers big ocean changeA study has uncovered a surprising and rapid shift in an important ocean layer which is fed by melted sea ice from Antarctica.The West Australian · 28 Oct, 18:02

In this story: Antarctic Intermediate Water · University of Melbourne · Bishakhdatta Gayen · Nature Climate Change

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