International Day for the Preservation of the Ozone Layer
Every year on September 16, the world celebrates the International Day for the Preservation of the Ozone Layer. In 2025, the chosen theme — “From Science to Global Action” — highlights the importance of combining scientific knowledge with collective commitment to protect our planet.
An exemplary international agreement
Signed in 1987, the Montreal Protocol remains one of the most successful environmental agreements in history. Its goal: to gradually eliminate substances that destroy the ozone layer, that natural shield high in the atmosphere that protects us from the sun’s harmful ultraviolet rays. Without this protection, the risks to human health (skin cancers, cataracts, weakened immune systems) and ecosystems would have been catastrophic.
International mobilization has been remarkable. Nearly 40 years after its signing, 99% of ozone-depleting substances are being phased out. In 2016, the 197 signatory states took a historic step by committing to gradually eliminate hydrofluorocarbons (HFCs), powerful greenhouse gases used mainly in refrigerators and air conditioners.
Tangible and encouraging results
Recent scientific data confirms the effectiveness of the Montreal Protocol. According to experts from the UN, NOAA, and NASA:
- The ozone layer could return to 1980 levels by 2066 over Antarctica,
- By 2045 over the Arctic,
- And as early as 2040 in the rest of the world.
These gains also come with unexpected benefits: by reducing ozone-depleting substances, the protocol has also helped slow global warming. Scientists estimate that this collective action delayed by about 15 years the first ice-free Arctic summer, providing valuable breathing room in the fight against climate change.
Direct health benefits are also expected. In the United States alone, the protocol’s implementation is projected to prevent about 443 million cases of skin cancer and millions of cataract cases by the end of the century.
Toward full recovery?
Encouraging news emerged in 2024. A study published in Nature Climate Change revealed that concentrations of certain harmful gases, such as hydrochlorofluorocarbons (HCFCs), are declining faster than expected. Moreover, observations from September 2024 showed that the Antarctic ozone hole reached its 7th smallest size since 1992.
These results are a sign of hope, but they also underline the need for vigilance. The success of the Montreal Protocol depends on all countries continuing to honor their commitments.
A success worth celebrating
In a context where environmental news is often alarming, the 2025 International Day for the Preservation of the Ozone Layer stands out as a source of inspiration. It proves that international cooperation, guided by science and translated into concrete action, can deliver results. As Kofi Annan declared back in 2003, the Montreal Protocol is “perhaps the single most successful international agreement to date.”
This collective achievement is an encouragement to continue along the path of cooperation and action, especially during this Season of Creation, to protect not only the ozone layer but also our climate and our common home.