Ozone hole largest on record over past 3 years, new research finds

Contrary to public perception, the Antarctic ozone hole has been amongst the largest on record over the past three years, new research has found.

The ozone hole above Antarctica has been remarkably massive and long-lived over the past four years and chlorofluorocarbons (CFCs) are not the only things to blame, said researchers in their study published in the journal Nature Communications.

CFCs are greenhouse gases containing carbon, hydrogen, chlorine and fluorine and have been studied to contribute to ozone depletion. The ozone layer in the Earth's atmosphere blocks the harmful ultraviolet (UV) radiation from the sun to protect people from skin diseases.

According to the study's lead author Hannah Kessenich, PhD candidate at the University of Otago, New Zealand, the team found much less ozone in the centre of the hole compared to 19 years ago.

"This means that the hole is not only larger in area, but also deeper throughout most of spring," said Kessenich.

The team analysed the monthly and daily ozone changes, at different altitudes and latitudes within the Antarctic ozone hole, from 2004 to 2022.

"We made connections between this drop in ozone and changes in the air that is arriving into the polar vortex above Antarctica. This reveals the recent, large ozone holes may not be caused just by CFCs," said Kessenich.

The researchers believe that there are complex factors contributing to the ozone hole, even as the 1987 Montreal Protocol on Substances that Deplete the Ozone Layer regulates the production and consumption of man-made chemicals known to deplete the ozone.

Therefore, they are raising concerns about how major communications about the ozone layer over the last few years have given the public the impression that the 'ozone issue' has been solved.

"While the Montreal Protocol has vastly improved our situation with CFCs destroying ozone, the hole has been amongst the largest on record over the past three years, and in two of the five years prior to that.

"Our analysis ended with data from 2022, but as of today the 2023 ozone hole has already surpassed the size of the three years prior - late last month it was over 26 million square kilometres, nearly twice the area of Antarctica," said Kessenich.

The researchers said that understanding ozone variability is important because of the major role it plays in the Southern Hemisphere's climate.

"We all know about the recent wildfires and cyclones in Australia and New Zealand and the Antarctic ozone hole is part of this picture.

"While separate from the impact of greenhouse gases on climate, the ozone hole interacts with the delicate balance in the atmosphere. Because ozone usually absorbs UV light, a hole in the ozone layer can not only cause extreme UV levels on the surface of Antarctica, but it can also drastically impact where heat is stored in the atmosphere," said Kessenich.