Over the past 25 years, the ozone hole above Antarctica has been shrinking, but recent research shows that it has been persisting for an unusually long time, lasting into December during the crucial period of new plant growth and peak breeding season for penguins and seals. This prolonged existence of the ozone hole allows more ultraviolet rays to get through the atmosphere, posing a threat to marine life, especially to the young ones.
The ozone layer depletion began over half a century ago due to the use of chlorofluorocarbons (CFCs) and related chemicals. Although these chemicals have been banned globally, their long lifetimes ensure that the ozone hole will continue to form every year. The majority of the ozone damage occurs over Antarctica, where the UV index doubles when the hole forms. However, most life forms in Antarctica, including marine life and Antarctica’s moss forests, are protected by snow and sea ice cover during the early spring when the ozone hole opens.
A series of unusual events between 2020 and 2023, including the record-breaking Australian bushfires, the huge underwater volcanic eruption off Tonga, and three consecutive years of La Niña, have resulted in longer-lasting ozone holes. These events have led to significant loss of sea ice, leaving many animals and plants with fewer places to hide.
Longer-lasting ozone holes expose summer-breeding animals around Antarctica’s vast coastline to high levels of reflected UV radiation. While penguins and seals have skin protection, their eyes aren’t protected, and their young ones may be more vulnerable. Marine creatures like krill will dive deeper into the water column, and fish eggs have melanin, the same protective compound as humans, though not all fish life stages are as well protected. Additionally, four of the past five years have seen a reduction in sea ice, making it harder for Antarctic phytoplankton and krill to survive, affecting the food web.
The outlook for Antarctica’s ozone layer remains uncertain, and climate change may delay the recovery of the ozone layer, making bushfires more common and severe. Ozone could also suffer from geoengineering proposals such as spraying sulphates into the atmosphere and more frequent rocket launches.
In conclusion, the persistence of the ozone hole into the summer could result in more damage to plants and animals, and immediate action is required to reduce carbon emissions into the atmosphere. Keeping ozone recovery on track is crucial for Antarctica’s wildlife and food web.
This article is written by Sharon Robinson, Distinguished Professor and Deputy Director of ARC Securing Antarctica’s Environmental Future (SAEF), University of Wollongong, Laura Revell, Associate Professor in Environmental Physics, University of Canterbury, and Rachele Ossola, Postdoctoral fellow, Colorado State University, and is republished from The Conversation under a Creative Commons license.
