The research published in Nature Communications suggests the Antarctic ozone layer has reduced by 26% since 2004, contrary to previous reports of recovery by actions taken under an agreement called the Montreal Protocol. 

The authors say wildfire and volcanic aerosols together with greenhouse gas emissions probably explain recent setbacks with record large, long-lived ozone holes re-emerging over Antarctica during Spring since 2020.

Climate change is influencing the severity and frequency of bushfires.

The ozone hole was previously thought to be under repair thanks to a global agreement signed in Montreal, Canada to limit ozone depleting substances. 

But the paper finds insignificant long-term change in the total ozone column since the early 2000s, “even where significant recovery has previously been reported”.

The analysis of daily and monthly ozone changes between 2001 – 2022, show delays in the formation of the ozone hole. While early springtime shows signs of recovery in the ozone layer, this is followed by declines during late September.

Researcher and author Hannah Kessenich from the University of Otago says: “by looking at detailed, daily ozone observations from the last 19 years, we find evidence of much less ozone in the centre of the Antarctic ozone hole compared to 19 years ago. This means that the hole has not only remained large in area, but it has also become deeper (i.e. has less ozone) throughout most of Antarctic spring.”

But Atmospheric scientist, Dr Martin Jucker from the University of NSW is not convinced by the results of the study.

He says: “Their results rely heavily on the large ozone holes we have seen in 2020-2022. However, existing literature has already found reasons for these large ozone holes: Smoke from the 2019 bushfires and a volcanic eruption (La Soufriere), as well as a general relationship between the polar stratosphere and El Niño Southern Oscillation […] The years 2020-22 have seen a rare triple La Niña, but this relationship is never mentioned in the study.”  

This Spring, the European Space Agency reported yet another large ozone hole had formed, among the biggest on record.

The layer of ozone high in the atmosphere protects the Earth from ultraviolet (UV) radiation from the Sun. Ozone depletion exposes people, particularly in the Southern Hemisphere, to a higher risk of skin cancer.

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