Study: Melting ice leaves emperor penguins with nowhere to molt, potentially killing thousands of them

Scientists have found that the annual event when emperor penguins completely shed and regenerate their feathers is putting the birds at risk as Antarctica changes due to warming.

This is stated in a study by British scientist Peter Fretwell, published in the scientific journal Communications Earth & Environment, the BBC reports.

Each year, the birds must remain on floating ice platforms long enough to replace their weathered feathers with new, waterproof layers. But between 2022 and 2024, climate change caused Antarctic sea ice to shrink significantly, depriving the birds of safe places to molt.

Now, scientists who track the animals using satellite imagery can no longer find most of the birds. They fear that thousands of penguins may have frozen to death in the icy waters of Antarctica.

The molting season is said to be the most dangerous for adult emperor penguins, as they are not wearing “waterproof suits” during this period. If they fall into the water, they are likely to die.

Little was known about the 30- to 40-day molt until Fretwell noticed large brown patches in satellite images from 2019 to 2025. They turned out to be piles of feathers left behind in an area called Mary Bird Land.

In 2019, 2020, and 2021, sea ice was relatively stable, with significant plume accumulations visible. But in 2022, summer sea ice across much of Antarctica declined sharply, falling from an average of 2.8 million km² to a record low of 1.79 million km² in 2023.

This trend continued until 2025, when there was a slight recovery of sea ice in West Antarctica. But when Fretwell looked at new satellite images, he saw few birds. Now he fears that they may have died. Some may have moved to other parts of East Antarctica to molt, but that would disrupt the breeding process and lead to population losses.

In the long term, the birdʼs best chance of survival is to adapt to molting on shallow ice shelves. Scientists have observed some groups starting to do this, although it can have negative consequences for the penguinsʼ breeding and feeding patterns.

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