Contrary to popular belief, the Antarctic ozone hole has grown significantly larger and longer-lived over the past four years, and University of Otago researchers believe that chlorofluorocarbons (CFCs) are not the only culprit.
In a study just published in nature communicationsThe group analyzed monthly and daily ozone changes at different altitudes and latitudes within the Antarctic ozone hole from 2004 to 2022.
Lead author Hanna Kesenich, a PhD candidate in the Department of Physics, said the researchers found that there was much less ozone at the center of the ozone hole than there was 19 years ago.
“This means that not only is the area of the hole larger, but it is also deeper throughout most of the spring.
“We found a link between this ozone loss and changes in the atmosphere that reach the polar vortex above Antarctica. This suggests that the recent large ozone hole is caused solely by CFCs. “We are making it clear that this is not the case,” she says.
The Montreal Protocol on Substances that Deplete the Ozone Layer, in force since 1987, regulates the production and consumption of man-made chemicals known to deplete the ozone layer, but researchers say other It is believed that the ozone hole is caused by a number of complex factors.
“Most of the major news coverage about the ozone layer in recent years has given the public the impression that the ‘ozone problem’ has been solved.
“While the Montreal Protocol has significantly improved the situation regarding ozone-depleting CFCs, the hole has been the largest on record for the past three years and for two of the five years before that.
“Our analysis ended with 2022 data, but as of today the 2023 ozone hole has already exceeded its size three years ago, and as of the end of last month it was over 26 million km wide. ”2, almost twice the area of Antarctica. ”
Ms. Kessenich believes it is important to understand ozone variations because it plays a major role in the climate of the Southern Hemisphere.
“We all know about the recent bushfires and cyclones in Australia and New Zealand, including the Antarctic ozone hole.
“Although independent of the effects of greenhouse gases on climate, the ozone hole interacts with the delicate balance in the atmosphere. Because ozone normally absorbs ultraviolet light, the hole in the ozone layer is As well as causing extreme UV radiation levels, however, it can also have a significant impact on where heat is stored in the atmosphere.
“Downstream impacts include changes in southern hemisphere wind patterns and surface climate, which can have local impacts.”
But she quickly allays fears about extreme UV rays.
“New Zealanders won’t have to worry about applying extra sunscreen this year, as the Antarctic ozone hole is not normally open over New Zealand and is mostly located directly above the South and South Pole. .”