WHEN BRITISH ANTARCTIC survey scientist Peter Fretwell spoke in July 2023 at the SCAR biology symposium in Christchurch, New Zealand, his words drew gasps of despair that later rippled around the world. SCAR – the Scientific Committee on Antarctic Research – represents scientists conducting research at Earth’s great frozen southern continent. The Christchurch gathering was their first face-to-face conference since the COVID pandemic began.
Peter, a cartographer renowned for monitoring wildlife at the planet’s remote poles by using high-resolution satellite imagery, was there to present some alarming news – evidence of catastrophic breeding failure in emperor penguins on the Antarctic Peninsula due to record low levels of sea ice.
Sea ice is frozen sea water, and it forms, metres deep, around Antarctica each winter. It floats on top of the ocean, clinging to the continent’s edge while stretching across the water for many kilometres. It retreats in summer, although never completely, and its seasonal fluctuations influence the global climate. It also profoundly and directly affects the Antarctic environment, where it influences ocean circulation, weather and the local climate. The rhythmic coming and going of sea ice is critical to all Antarctic life, from crabeater, Weddell and leopard seals, to humpback whales, Adélie and chinstrap penguins, and Antarctic skuas. But it’s particularly important to emperor penguins because it’s the place where most of them breed.
In the depths of winter, when the sea ice is at its greatest, these penguins congregate in their hundreds or thousands in noisy colonies, buffeted by the coldest and strongest winds on the planet. Here they find partners, court, mate, and produce no more than one chick per pair each year. The fluffy down of the chicks isn’t waterproof, but the sleek plumage of adult penguins is, allowing them to ‘fly’ at extraordinary speeds with great agility through freezing waters, hunting prey such as fish and the tiny prawn-like crustaceans called krill. About 60 emperor colonies form on Antarctic sea ice every year.
The extreme remoteness and conditions mean satellite imagery is often the only way of locating
