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Effects & Impacts: Antarctic sea ice loss

Bellingshausen Sea image: Sonny Whitelaw

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Antarctic sea ice loss

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Summary

  • Recommended: A world with less ice. Beautifully presented 2025 multimedia feature explaining what’s happening in Antarctica and what it means for the world. 
  • Sea ice grows throughout the autumn and winter and then melts throughout the spring and summer. It acts like an insulating blanket over the ocean, moderating the exchange of heat and gases (including carbon dioxide) between the Southern Ocean and relatively cooler atmosphere in autumn and winter, and it protects the coastline, which is largely made up of ice shelves:

The removal of this buffer increases coastal exposure which can destabilise ice shelves, potentially increasing the flow of Antarctic glaciers and adding to sea level rise. This summer has set a new record for the length of Antarctic coastline exposed to damaging swells and surface ocean warming. – Reid, 2024

The planetary cooling effect of sea ice has reduced by 14% since the 1980s – Duspayev et al, 2024

  • The lowest Antarctic sea ice extent in a 44-year data record was in 2023, when the was a 38% loss compared to the 1979–2022 average (Fig. 1). This was followed by a catastrophic failure of winter sea ice to form. Video 1 explains why this continued in 2024 and 2025, and the implications.

Our new study has revealed that the Southern Ocean is changing, but in a different way to what we expected. We may have passed a tipping point and entered a new state defined by persistent sea ice decline, sustained by a newly discovered feedback loop…Antarctica is no longer the stable, frozen continent we once believed it to be. It is changing rapidly, and in ways that current climate models didn’t foresee. Until recently, those models assumed a warming world would increase precipitation and ice-melting, freshening surface waters and helping keep Antarctic sea ice relatively stable. That assumption no longer holds. – Silvano, July 2025

Antarctic summer sea ice is at record lows. Here’s how it will harm the planet – and us. – Doddrige et al, July 2025

  Effects

Home > Climate wiki > Effects > Antarctic sea ice loss

Summary

  • Recommended: A world with less ice. Beautifully presented 2025 multimedia feature explaining what’s happening in Antarctica and what it means for the world. 
  • Sea ice grows throughout the autumn and winter and then melts throughout the spring and summer. It acts like an insulating blanket over the ocean, moderating the exchange of heat and gases (including carbon dioxide) between the Southern Ocean and relatively cooler atmosphere in autumn and winter, and it protects the coastline, which is largely made up of ice shelves:

The removal of this buffer increases coastal exposure which can destabilise ice shelves, potentially increasing the flow of Antarctic glaciers and adding to sea level rise. This summer has set a new record for the length of Antarctic coastline exposed to damaging swells and surface ocean warming. – Reid, 2024

The planetary cooling effect of sea ice has reduced by 14% since the 1980s – Duspayev et al, 2024

  • The lowest Antarctic sea ice extent in a 44-year data record was in 2023, when the was a 38% loss compared to the 1979–2022 average (Fig. 1). This was followed by a catastrophic failure of winter sea ice to form. Video 1 explains why this continued in 2024 and 2025, and the implications.

Our new study has revealed that the Southern Ocean is changing, but in a different way to what we expected. We may have passed a tipping point and entered a new state defined by persistent sea ice decline, sustained by a newly discovered feedback loop…Antarctica is no longer the stable, frozen continent we once believed it to be. It is changing rapidly, and in ways that current climate models didn’t foresee. Until recently, those models assumed a warming world would increase precipitation and ice-melting, freshening surface waters and helping keep Antarctic sea ice relatively stable. That assumption no longer holds. – Silvano, July 2025

Antarctic summer sea ice is at record lows. Here’s how it will harm the planet – and us. – Doddrige et al, July 2025

  • Sea ice or icebergs: what's the difference?

    Some incoming radiation from the sun is reflected back into space due to the albedo effect of the cryosphere (ice caps, permafrost, glaciers) and atmospheric aerosols much of which, paradoxically, come from burning fossil fuels. About 89% of the retained excess heat is being absorbed by the oceans. The land takes up ~6%, the cryosphere absorbs ~4%—which is why it’s rapidly melting—and the remaining 1% is in the atmosphere.

    • Icebergs: are made of that has broken off a glacier or ice shelf and floats out to sea or into lakes. The photo at the top of this page was taken in summer in the Bellingshausen Sea, showing a few small icebergs.
    • Sea ice: forms when ocean water freezes over autumn and winter. Although sea ice is made from salty seawater, there isn’t much room for salt molecules to be trapped in the close-knit structure of ice, so the salt molecules are rejected into a dense, briny solution that drops into deeper water. This plays a crucial role in driving the world’s two largest ocean currents.  

    An area of ice nearly the size of Texas has failed to form over the Bellingshausen Sea, off western Antarctica, as researchers investigate the links between sea ice loss and global warming. Satellite observations have revealed that around 250,000 square miles (650,000 square kilometers) of sea ice hasn’t formed yet, compared with the average amount of sea ice between 1991 and 2020. –  Live Science 17 June 2026

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