Record-Low Antarctic Sea Ice Disrupts Critical Life Stage for Emperor Penguins

Communications Earth & Environment, 26 February 2026

For thousands of years, emperor penguins have relied on stable, coastal sea ice to safely molt, a vulnerable period when they regrow waterproof feathers and cannot enter the ocean to feed. However, recent record-low Antarctic sea ice has caused some of these platforms to melt before molting was complete. Molting sites along Marie Byrd Land in particular have, in low-ice years, disintegrated before the birds finished regrowing their waterproof feathers. Penguins that enter the water half-molted are at risk of hypothermia and predation, especially after losing up to half their body weight. Before 2022, over 100 penguin groups were identified in the region, but in 2025, only 25 small groups were visible, despite more favorable sea ice conditions. Climate-driven ice loss may now be affecting adult molting, potentially exposing large portions of the global emperor penguin population to a new mortality risk.

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