Shrinking Antarctic sea ice is warming the ocean faster than expected

The collapse of sea ice around the Antarctic continent led to a doubling of the number of icebergs from glacial caps and an increase in sea temperatures, and the impacts become more serious as heat accumulates in the southern ocean.

The extent of sea ice in both poles has hated harsntly over the past decade. In 2023, the area of ​​winter sea ice in Antarctica was a record of 1.55 million square kilometers below the average expected extent.

This is equivalent to the disappearance of an ice area almost 6.5 times the size of the United Kingdom. The extent of the ice in 2024 was almost as low and 2025 follows a similar level.

Edward Doddridge at the University of Tasmania, Australia, and his colleagues decided to understand the implications of a long -term and radically reduced sea -ice pad in Antarctic.

The team noted that in summer with low sea ice since 2016, the loss of sea ice caused an increase of 0.3 ° C of average temperature in the southern ocean between latitudes of 65 ° and 80 ° in the south.

More worrying, the additional heat of a single year of ice -based ice did not dissipate the following year. In fact, he kept the warm ocean for at least the next three years, making the temperature much more serious than expected, explains Doddridge.

“We have known for some time that the loss of sea ice in summer should warm the ocean, mainly because the sea ice and the snow that are on it are really reflective,” explains Doddridge.

“The fact that the oceanic memory of warming lasts three whole years gives the possibility of reheating the impact in the Southern Ocean.

Another consequence of such a serious drop in sea ice is that it can cause faster loss of interior ice caps. When the surface of the ocean is frozen, it reduces the swelling of the south of the ocean, preventing them from hitting the edges of the ice caps which overlap the Antarctic continent. Once the protective skirt of sea ice has disappeared, the ice caps on the coastal margin begin to break more easily.

The team noted that for a reduction of 100,000 square kilometers of sea ice, there were six additional icebergs greater than 1 square kilometer broken down. “During the years of low ice, we saw twice as much icebergs,” said Doddridge.

The loss of sea ice will also seriously affect species that depend on the possibility of withdrawing from the ocean on a solid platform for their survival. The study predicts that species such as emperors penguins (Forsteri Aptenodytes) and crabate seals (Lobodon carcinophagus) can be particularly affected.

Antarctic science is also made more difficult because sea ice plays an essential role in the permit to safely replenish research stations.

Nerilie Abram at the Australian National University says that there are “very few winners in this analysis of how the loss of sea ice will affect the environment there”.

“When we have an extremely low year of sea ice, there is an impact that the Antarctic system will continue for many years. It’s not just a unique event, ”explains Abram. “There are just a multitude of ways of which this loss of sea ice has an impact on antarctic ecosystems.”