The hole in the ozone layer was smaller in 2024 than in recent years, according to the WMO, indicating a positive development for environmental and planetary health.
The WMO Ozone Bulletin reports that the low level of ozone depletion was partly due to naturally occurring atmospheric factors which drive year-to-year fluctuations. However, the long-term positive trend reflects the success of concerted international action.
The depth of the 2024 Antarctic ozone hole – which appears over the Antarctic every spring – was below the 1990–2020 average, with a maximum ozone mass deficit (OMD) of 46.1 million metric tons on September 29, 2024. It was smaller than the relatively large holes between 2020 and 2023.
Its onset was relatively slow, and delayed ozone depletion was observed through the month of September, followed by a relatively rapid recovery after the maximum deficit was reached.
“This persistent later onset has been identified as a robust indication of initial recovery of the Antarctic ozone hole,” said the Bulletin.
The bulletin was issued for World Ozone Day on September 16 and the 40th anniversary of the Vienna Convention, which recognized stratospheric ozone depletion as a global problem and provided the framework for mobilizing international cooperation in ozone research, systematic observations and scientific assessments.
“Forty years ago, nations came together to take the first step in protecting the ozone layer – guided by science, united in action,” commented United Nations secretary-general António Guterres.
“The Vienna Convention and its Montreal Protocol became a landmark of multilateral success. Today, the ozone layer is healing. This achievement reminds us that when nations heed the warnings of science, progress is possible.”
To date, the Montreal Protocol has led to the phase-out of over 99% of the production and consumption of controlled ozone-depleting substances, which were used in refrigeration, air conditioning, firefighting foam and even hairspray.
As a result, the ozone layer is now on track to recover to 1980s levels by the middle of this century, the WMO states, which significantly reduces the risks of skin cancer, cataracts and ecosystem damage due to excessive UV exposure.
WMO secretary-general Celeste Saulo added, “WMO’s scientific research into the ozone layer dates back decades. It is underpinned by trust, international collaboration and commitment to free data exchange – all cornerstones of the world’s most successful environmental agreement.”
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