The ozone layer shows signs of recovery thanks to international cooperation and scientifically supported policy. Monitoring remains necessary because natural phenomena can unexpectedly influence it. Therefore, it is important to continue to monitor the ozone layer and investigate whether agreements between countries are effective. On World Ozone Day, September 16, the World Meteorological Organization calls attention to the ozone layer.
This years theme for World Ozone Day - From science to global action - underscores how scientific insights form the basis for international agreements and environmental policy.
From concern to policy
Forty years ago, the Vienna Convention was globally agreed to protect the ozone layer.
Forty years ago, growing concerns about the thinning ozone layer and the discovery of the ozone hole over Antarctica led to the Vienna Convention. In this, countries worldwide agreed to protect the ozone layer. Two years later, the Montreal Protocol followed. In it, countries agreed to gradually stop using harmful substances, such as CFCs, which were widely used in cooling systems and aerosol sprays, and were found to be responsible for the breakdown of ozone in the stratosphere.
What makes the Montreal Protocol unique is the speed with which scientific findings have been translated into international policy. When the Vienna Convention was signed in 1985, the exact cause of the ozone hole over Antarctica was not yet fully understood. Within a few years, research showed that chlorine compounds, along with ice crystals at very low temperatures, were breaking down the ozone layer.
Preventing a tipping point
Without the Montreal Protocol, the ozone layer would have shrunk by two-thirds later this century – a rapid change with significant consequences for animals, plants, and humans.
Thanks to this knowledge, countries worldwide could take targeted measures together. Meanwhile, the concentration of ozone-depleting substances in the atmosphere has been steadily decreasing, and the ozone layer shows signs of recovery. However, we must remain vigilant. New studies show that ozone depletion is not a gradual process. Without the Montreal Protocol, the ozone layer would have shrunk by two-thirds in five to ten years later this century – a rapid change with significant consequences for animals, plants, and humans.
Parallels with climate policy
The approach to the ozone problem is often seen as an example of international cooperation on climate change. Here too, scientific consensus plays an important role. In 2015, knowledge about the impact of greenhouse gases led to the Paris Agreement, in which countries agreed to limit the emissions of CO₂ and other greenhouse gases.
Natural disturbances
Although the ozone layer is recovering, monitoring remains essential. Two events illustrate this:
- The eruption of the underwater volcano Hunga Tonga Ha’apai in 2022 brought large amounts of water vapor into the ozone layer, with measurable effects to this day, including changes in weather patterns in the Southern Hemisphere.
- Wildfires in Australia in 2020 caused an injection of smoke particles into the stratosphere, resulting in temporary ozone depletion.
These events show that natural phenomena can unexpectedly influence the atmosphere. Therefore, it is important to continue monitoring the ozone layer and investigate whether agreements between countries are effective.
