Discovery and warning
In 1913 French physicists Charles Fabry and Henri Buisson used UV absorption to show that ozone is concentrated high in the atmosphere, and in the 1920s Britain's Gordon Dobson built a spectrometer to measure total ozone, which is why it is still counted in Dobson units. In 1974 Mario Molina and Sherwood Rowland at the University of California warned that chlorofluorocarbons (CFCs) from fridges and aerosol cans break apart in the stratosphere, releasing chlorine atoms that can each destroy tens of thousands of ozone molecules. Industry pushed back, but in 1985 Joseph Farman's British Antarctic Survey team reported springtime ozone over Antarctica had fallen by nearly 40%, the "ozone hole." Molina, Rowland and Paul Crutzen shared the 1995 Nobel Prize in Chemistry.
The Montreal Protocol and recovery
Just two years after the hole was announced, nations signed the 1987 Montreal Protocol to phase out CFCs. It became the first treaty ratified by every UN member and is widely called the most successful environmental agreement ever. The 2022 WMO assessment found the layer is healing: Antarctic ozone should return to 1980 levels around 2066 and most other regions around 2040. Replacement HFCs spare ozone but are potent greenhouse gases, so the 2016 Kigali Amendment added them to the phase-down, linking the ozone story to net-zero climate policy.
Good ozone, bad ozone
Stratospheric ozone protects life, but ozone near the ground is a pollutant formed when nitrogen oxides from traffic react in sunlight. Summer ozone alerts refer to this kind, which causes coughing and shortness of breath and worsens asthma. A thinner ozone layer lets more UV-B reach the surface, raising the risk of cataracts and skin cancer, so sun protection matters on high-UV days. Although they are all air problems, fine dust and acid rain have different causes and fixes.
FAQ
- Is the ozone hole causing global warming?
- Not directly. Warming is driven by greenhouse gases like CO₂, while the ozone hole was caused by CFCs. CFCs and HFCs are also greenhouse gases, though, so the two issues overlap.
- Is the ozone layer still being destroyed?
- CFC levels are falling and the layer is recovering. The Antarctic hole still varies year to year, and full recovery will take several more decades.
Sources reviewed: 2026-10-26
References
- Farman, J. C., Gardiner, B. G., & Shanklin, J. D. (1985). Large losses of total ozone in Antarctica reveal seasonal ClOx/NOx interaction. Nature, 315, 207–210.
- Molina, M. J., & Rowland, F. S. (1974). Stratospheric sink for chlorofluoromethanes: chlorine atom-catalysed destruction of ozone. Nature, 249, 810–812.
- WMO/UNEP (2022). Scientific Assessment of Ozone Depletion: 2022. World Meteorological Organization.