As global temperatures rise, Antarctica’s sea ice is disappearing, wreaking havoc on its wildlife. The continent is predominantly covered by an ice sheet. But accelerating greenhouse gas emissions are trapping heat, causing it to melt at an alarming rate. In the 1980s, Antarctica lost an average of 40 billion tonnes of ice per year. By 2020, the rate of ice loss had increased to 252 billion tonnes annually. The ecosystem is changing, and species that depend on the ice are struggling to survive.

Krill, the tiny but mighty organism, forms the foundation of the Antarctic food chain. These shrimp-like crustaceans are packed with nutrients vital to larger predators. However, the disappearance of sea ice is compromising krill’s survival.

Professor Jennifer Verduin, oceanographer and Pro Vice Chancellor of Environmental Sciences at Murdoch University, recently returned from Antarctica. She explains, “Krill moult under the ice for protection. With less ice, they’re more vulnerable, reducing their numbers and ultimately the food supply for the larger predators”. Since the 1970’s, krill has declined by 80%.  

The decline in krill has a cascading effect, reducing the food supply for species like humpback whales. These whales migrate to Antarctica each year to feed on krill. As food availability shifts, they must travel farther, using more energy. This impacts not only the current generation but also future survival rates, as pregnancy rates drop in years of low krill abundance.

Image credit: Adélie Penguin floating on sea ice in Antarctica, 2018, photo by James Rathmell on Unsplash.

Emperor penguins are an indicator species, meaning their population and breeding reflect the health of the Antarctic ecosystem. These penguins rely on stable ice to survive. For nine months each year, they breed, incubate their eggs, and raise their young on the frozen surface. If the sea ice breaks up during this process, it can have fatal consequences.

Record-low sea ice in 2022 led the eastern Bellingshausen Sea region, west of the Antarctic Peninsula, to experience a 100% loss in sea ice concentration. Of the five penguin breeding sites located in this region, only one survived. This is the first recorded incident of such a widespread breeding failure. If sea ice continues to decline at this rate, emperor penguins will become quasi-extinct by 2100 as 98 percent of colonies will disappear.  

Image credit: Leopard Seal lying on snow, 2010, photo by Peter Rejcek, United States Antarctic Program.

Leopard seals, Antarctica’s apex predators, are also struggling as sea ice declines. Traditionally, they hunt on ice, ambushing penguins and smaller seals. But with shrinking ice, they are shifting to more open-water hunting. This hunting becomes more challenging, forcing them to target easier prey. At Cape Shirreff, researchers have observed larger female leopard seals preying heavily on fur seal pups. Since 2010, they have consumed nearly 70% of the pups born each year, contributing to a drastic decline in the fur seal population.

Despite the challenges, hope remains for Antarctic wildlife conservation. The Ross Sea Marine Protected Area (MPA)—established in 2016 and covering 2.09 million square kilometres—has been crucial in safeguarding critical habitats and promoting species recovery. New proposals aim to expand MPA networks to protect additional breeding and foraging grounds for wildlife.

As Professor Verduin aptly states, “Antarctica is where all the oceans come together. What we do here affects areas in Antarctica. To keep the world under 1.5 degrees of warming, we must act as a whole system.” With unified global efforts and continued innovation in conservation, Antarctica’s wildlife can survive.