Antarctica’s Ozone Hole Is Persisting Later Into the Year, Raising Concerns for Wildlife

A hole in the ozone layer that appears annually over Antarctica is persisting later into each year, and biologists say this puts wildlife at risk. The gap allows more ultraviolet B radiation onto the planet, which threatens animals with eye damage and other health impacts, per a paper published last week in the journal Global Change Biology.

Each year, the ozone hole typically peaks in size between September and October, when ice coverage reflects much of the sun’s harmful ultraviolet rays away. But in the last four years, the hole has remained into the Southern Hemisphere’s summer in December, in part due to climate change-fueled bush fires in Australia and natural volcanic eruptions. As a result, more radiation from the sun is reaching Earth’s surface at a time when snow and ice is melting, leaving more plants and animals exposed.

“Whilst ozone is recovering, we’ve seen these four years of ozone holes that have been large but also have [stayed open] into December, which is the thing that’s most concerning for us as biologists,” Sharon Robinson, first author of the study and a climate change biologist at the University of Wollongong in Australia, tells the Sydney Morning Herald’s Bianca Hall. “Because that’s when most of the life comes to life in Antarctica each summer. In the winter, everything’s under snow and ice.”

The ozone layer is a thin blanket in the stratosphere made of molecules with three oxygen atoms. It absorbs harmful UVB light from the sun, which can cause cancer and eye damage in humans, according to the Environmental Protection Agency (EPA).

Scientists realized in the 1970s that this protective sheen was wearing away as a result of human activity. The ozone “hole” isn’t a total absence of ozone—it’s a spot in the layer where concentrations of the protective gas have dropped below a certain historical level. In 1987, countries around the world adopted the Montreal Protocol, agreeing to phase out the use of chemicals harmful to the ozone layer, including chlorofluorocarbons, used in aerosol sprays, firefighting foams, refrigerants and other materials.

This agreement was highly effective—the ozone hole reached its peak size in 2006 and has been shrinking since then. Now, scientists think the ozone layer could fully recover by the middle of the century.

“When I tell people I work on the ozone hole, they go: ‘Oh, isn’t that better now?” Robinson tells BBC News’ Victoria Gill.

But the fact that the hole is lasting longer provides “a wake-up call,” Jim Haywood, an atmospheric scientist at the University of Exeter in England who did not contribute to the findings, tells the publication. “Society cannot be complacent about our achievements in tackling it.”

While the ozone layer is recovering, events on Earth—both human-caused and natural—are still delaying that process. Australian bushfires in 2019 and 2020, which scorched as much as 70,000 square miles of land and impacted nearly three billion animals, released particles called aerosols into the air that can damage the ozone layer.

“With climate change, one of the things we’re seeing is more frequent bushfires,” Robinson says to the Sydney Morning Herald. “We’ll always have bushfires, but we’re having more of them because it’s drier and warmer and the weather conditions are more extreme.”

The massive Hunga Tonga-Hunga Ha’apai volcanic eruption in Tonga in 2022 also spewed aerosols. Even rocket launches and geoengineering projects using aerosols have the potential to further delay the ozone’s recovery, per the paper.

These events have likely contributed to the ozone hole over Antarctica staying open later into the year, the scientists write. Sea ice extent drops by about 25 percent between early October and early December—and since ozone depletion has recently continued into this period of reduced ice coverage, animals are being left more vulnerable, per the paper.

Penguins and seals are protected from sunburn because of their feathers and fur, but their eyes have no such shield. However, few studies have examined the impacts of ultraviolet radiation exposure on animals—and the ones that do probe this issue have usually been conducted in zoos, the study authors write in the Conversation.

“More UV radiation in early summer could be particularly damaging to young animals, such as penguin chicks and seal pups who hatch or are born in late spring,” they write in the Conversation.

Increased radiation exposure can inhibit the photosynthesis of plankton, per the paper. Antarctic krill, which feed on plankton, might dive deeper into the water to escape the harmful rays, and studies have also found increased death rates in krill larvae after ultraviolet radiation exposure. These organisms form the basis of the Antarctic food chain, and impacts to them could in turn affect seabirds, seals, penguins and whales, per BBC News.

Additionally, more sea ice is melting in the Antarctic due to global warming, making the ozone hole more harmful, the study authors note.

“The biggest thing we can do to help Antarctica is to act on climate change—reduce carbon emissions as quickly as possible so we have fewer bushfires and don’t put additional pressure on ozone layer recovery,” Robinson tells BBC News.

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Will Sullivan is a science writer based in Washington, D.C. His work has appeared in Inside Science and NOVA Next.