Antarctic emperor penguins are threatened with extinction due to shrinking sea ice as by the end of 2023 a fifth of their colonies have failed to breed, according to British Antarctic Survey scientists on Thursday.

Emperor penguins – the largest species in the world and one of two endemic species to Antarctica – they depend on sea ice firmly attached to the shore to lay their eggs and raise their chicks. If the ice breaks too early, the chicks will be forced into the sea before their waterproof wings are fully developed.

“They’ll either freeze to death or drown,” says Peter Fretwell, a British Antarctic Survey scientist who studies wildlife using satellites.

Of the 66 colonies 14 failed to breed last year, as Antarctic sea ice extent shrank to record low; partly due to warming from climate change. Tens of thousands of chicks are believed to have died.

Spring and summer sea ice extent around Antarctica has declined significantly over the past seven years, with 2022 and 2023 seeing the lowest summer records.

Although ice shrinkage in 2023 was greater than the previous year in almost all months of the breeding season, emperor penguin colonies experienced fewer breeding failures than in 2022, when a third of all colonies failed to breed, said Fretwell.

This is partly because there have been lfewer sea ice breakup events in 2023;while some penguins also appeared to adapt to the changing conditions.

Fretwell, who has been tracking penguin movements and breeding failures via the Copernicus Programme’s Sentinel-2 satellite, said roughly some of the affected colonies in 2022 moved to another breeding site.

Some moved south for better ice, while other colonies climbed onto more stable ice patches or large icebergs to try to avoid the worst conditions.

However, scientists predict that 99% of emperor penguins will be gone by the end of this century, if sea ice continues to decline due to climate change fueled by the burning of fossil fuels.