The ozone hole doesn’t appear to be recovering after all, according to a new study, although not everyone agrees on that Science & Planet

The ozone layer is located at an altitude ranging between 11 and 40 kilometers above the Earth’s surface. This layer acts as a filter for most of the sun’s ultraviolet rays, which can cause skin cancer. Since the 1970s, chemicals (chlorofluorocarbons) have been reducing ozone levels, resulting in large annual gaps. These are mainly located over Antarctica. The 1987 Montreal Protocol banned these CFCs. With the entry into force of this international environmental cooperation, the ozone layer over Antarctica is expected to recover by 2066.

Despite the decline in CFCs, researchers from New Zealand now report in a new study published in Nature Communications that there is no significant reduction in the Antarctic ozone hole. They say the center of the hole shows a decrease in ozone over time. Six of the past nine years have been characterized by low ozone levels and large ozone holes.

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Scientists point out that weather changes, perhaps due to climate change, are masking some of the recovery. But they did not investigate this in detail. They say a combination of wildfires, volcanic aerosols and greenhouse gas emissions explains the recent setbacks, with record-sized ozone holes appearing over Antarctica in the spring since 2020. Hannah Kicinich, lead author of the study Confirms The Montreal Protocol and CFC reductions remain on track. But their findings show that other factors may be contributing to recent ozone problems.

However, scientist Martin Jucker attaches little credibility to the study’s findings. He points to The conclusions depend largely on the large ozone holes of 2020-2022. Existing literature has already found explanations for these large ozone holes, such as smoke from the 2019 wildfires, volcanic eruptions, and a connection between the polar stratosphere and a rare triple La Niña in 2020-2022. Additionally, the analysis ignored data from 2002 and 2019, years in which smaller ozone holes formed due to polar vortex disruption.

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Previous studies showed that the ozone hole increased by 10 percent in 2020 due to widespread forest fires on “Black Saturday” in Australia. The eruption of the Hunga-Tonga-Hunga-Haapai volcano off the coast of Tonga in 2022 is also believed to have affected modern ozone levels. “It is not clear why the authors chose to exclude data from 2002 and 2019 from the study, but not data for 2020-2022, when all these years were affected by very special and rare events,” Joker said.

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