Emperor penguins suffered mass breeding failures in 2023 amid record low sea ice

"They'll either freeze to death or they'll drown," said Peter Fretwell, a scientist with the British Antarctic Survey who studies wildlife using satellites. That happened in 14 of Antarctica's 66 emperor penguin colonies last year as the extent of Antarctic's sea ice shrank to a record low, driven in part by climate change-fuelled heating.

Record low sea ice in late 2023 led to breeding failures in one-fifth of Antarctica's emperor penguin colonies, scientists with the British Antarctic Survey said on Thursday.

Emperors - the world's largest penguin species and one of only two endemic to Antarctica — depend on sea ice firmly attached to the shore to lay their eggs and raise their chicks. If ice breaks up too early, the chicks will be forced to enter the sea before their waterproof feathers have fully come in. "They'll either freeze to death or they'll drown," said Peter Fretwell, a scientist with the British Antarctic Survey who studies wildlife using satellites.

That happened in 14 of Antarctica's 66 emperor penguin colonies last year as the extent of Antarctic's sea ice shrank to a record low, driven in part by climate change-fuelled heating. Tens of thousands of chicks are likely to have died. The extent of spring and summer sea-ice around Antarctica has fallen significantly over the past seven years, with 2022 and 2023 registering record summer lows.

Although 2023 saw a lower sea ice extent than the year before in nearly all months of the breeding season, emperor penguin colonies experienced fewer breeding failures than in 2022, which saw breeding failures at a third of all colonies, Fretwell said. That was partly because there were fewer sea ice break-up events in 2023, while some birds also seemed to adapt to the changed conditions.

"Maybe half a dozen or so of the colonies that were affected in 2022 took action and moved their breeding locations," said Fretwell, who surveyed the birds' movements and breeding failures via the Copernicus Programme's Sentinel-2 satellite. Some moved south to better ice, while other colonies went up on to more stable ice shelves or large icebergs to try to avoid the worst conditions.

This, Fretwell said, was reassuring "because it just shows these birds will adapt to the changing conditions to a certain extent". Still, scientists predict that 99% of emperor penguins will be lost by the end of this century if sea ice continues to decline due to climate change fuelled by the burning of fossil fuels.

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