The Hole In The Ozone Layer Is Healing And On Track For Full Recovery In The 21st Century, Thanks To Science

The latest WMO Ozone Bulletin says the ozone hole in 2024 was significantly smaller than in previous years. While some of this was due to naturally occurring atmospheric factors that drive year-to-year fluctuation, it fits into a larger trend that shows a long-term recovery. 

Globally, stratospheric ozone levels were higher in 2024 compared with recent years. Over Antarctica, the ozone depletion that occurs each spring reached its peak on September 29, with a maximum ozone mass deficit of 46.1 million tonnes, which is smaller than the unusually large holes recorded between 2020 and 2023, and well below the 1990–2020 average. This indicates the hole is recovering and ozone levels are bouncing back. 

The ozone layer is a region of the stratosphere between 15 and 30 kilometers (9.3 to 18.6 miles) above the Earth’s surface that has a high concentration of the gas ozone compared to other parts of the atmosphere.

It helps to absorb harmful ultraviolet rays from the Sun, acting as an invisible shield for life on Earth. Without it, or with a large hole in it, we would be bombarded with far more radiation, leading to higher rates of skin cancer, cataracts, and immune system damage, while also disrupting ecosystems, particularly plankton at the base of the ocean food chain.

In the 1970s and 80s, scientists discovered there was a hole in the ozone layer above Antarctica. It transpired that the layer was being degraded by chlorofluorocarbons (CFCs) – synthetic gases once extensively used in aerosol sprays, solvents, and refrigerants. After wafting up into the stratosphere, CFCs release chlorine atoms that catalyze the breakdown of ozone molecules, creating a “hole” in the layer.

Remarkably, the world came together to solve this problem. In 1987, just two years after the publication of the ozone hole discovery, 197 countries and the European Union signed the Montreal Protocol, which saw the phase-out of CFCs and made precautions that would allow the agreement to later ban ozone-depleting chemicals that were yet to be invented. 

“Forty years ago, nations came together to take the first step in protecting the ozone layer – guided by science, united in action,” António Guterres, United Nations Secretary-General, said in a statement.

“Today, the ozone layer is healing. This achievement reminds us that when nations heed the warnings of science, progress is possible,” he said.

Its slow but steady recovery over the past few decades has been well documented. Earlier this year, an MIT-led study showed with high statistical confidence that ozone recovery is real and directly attributed to curbing ozone-depleting chemicals, not shifting weather patterns.

If current policies hold strong, the ozone layer is expected to fully recover by around 2066 over the Antarctic, by 2045 over the Arctic, and by 2040 for the rest of the world.

The success of the Montreal Protocol naturally raises a bigger question: if the world was able to unite to heal the ozone layer, could we do the same to tackle climate change? Unfortunately, it might not be so simple. 

“The climate story is much, much more difficult than the ozone story. What the Montreal Protocol showed is that you start with very small steps, but you get it better as the science gets better, and as you get more people onboard. That’s not really happening with climate, and for good reasons: Climate is very complicated,” Professor John Pyle, a leading atmospheric chemist and former Co-Director of the Centre for Atmospheric Science, who was instrumental in the Montreal Protocol, told IFLScience in May 2025.

“That is a lesson the politicians haven’t learned: when you have exponential growth, if you cut it off as quickly as possible, you solve a lot of future problems. And they don’t want to do that,” added Jonathan Shanklin, a meteorologist who made the first recordings of ozone depletion in Antarctica.