Shrinking Antarctic sea ice is warming the ocean faster than expected

The decline in sea ice around the Antarctic continent has resulted in a significant increase in the number of icebergs breaking off from ice sheets and a rise in sea temperatures, with the impacts becoming more severe as heat accumulates in the Southern Ocean.

Over the past decade, there has been a drastic decrease in sea ice extent at both poles. In 2023, the Antarctic winter sea ice area was 1.55 million square kilometers below the average extent, equivalent to an area nearly 6.5 times the size of the UK. Subsequent years have also seen low ice extents, with 2025 on track to reach similarly concerning levels.

Research conducted by Edward Doddridge and his team at the University of Tasmania has revealed that the loss of sea ice in Antarctica since 2016 has led to a 0.3°C increase in average temperatures in the Southern Ocean between latitudes 65° and 80° south. This temperature rise persists for at least three years, compounding the warming effect over time.

The absence of sea ice may also accelerate the loss of inland ice sheets as it exposes them to more frequent breaking by Southern Ocean swells. Doddridge’s team found that for every 100,000-square-kilometer reduction in sea ice, there were six additional icebergs larger than 1 square kilometer breaking away, indicating a faster rate of ice sheet disintegration.

In addition to environmental impacts, the decline in sea ice will have severe consequences for species like emperor penguins and crabeater seals that rely on solid platforms for survival. It will also pose challenges for Antarctic research activities, as sea ice plays a crucial role in facilitating safe resupply missions to research stations.

Nerilie Abram from the Australian National University emphasizes the far-reaching effects of sea ice loss on Antarctic ecosystems, highlighting the long-lasting repercussions of extreme low sea ice years. The compounding impact of warming oceans and increased ice sheet breakage underscores the urgent need to address the ongoing decline in Antarctic sea ice.