A single iceberg that grounded off the coast of Antarctica triggered a catastrophic breeding collapse in one of the world's largest emperor penguin colonies, wiping out nearly 70 percent of its chicks in a single season, according to research published in Communications Earth & Environment by a South Korean team.
The iceberg, nearly 14 kilometres long, broke from the Nansen Ice Shelf and lodged on the seabed near Coulman Island in July 2024. It created a cliff tens of metres high that extended the penguins' route to open water from roughly 9 to almost 15 kilometres. Only 6,658 living chicks were counted during the 2025 breeding season, a 69 percent drop from the previous year, as thousands starved unable to navigate the barrier.
The findings arrive as the International Union for Conservation of Nature classifies emperor penguins as endangered on its Red List, with Antarctic sea ice estimated to have passed a tipping point several years ago.