A groundbreaking study led by MIT scientists has confirmed that the Antarctic ozone layer is healing, a direct result of the global effort to reduce ozone-depleting substances. This new research provides the most statistically confident evidence to date, confirming that the recovery of the ozone layer is primarily due to human interventions aimed at curbing harmful chemicals, as opposed to other factors like natural weather variability or the increase of greenhouse gases in the stratosphere.
For many years, scientists have observed signs of the ozone layer’s recovery, but until now, no study has been able to conclusively prove that these changes are due to the reduction in ozone-depleting substances. The new study, published in the journal Nature, is the first to quantify this recovery with high statistical confidence.
“This is really the first study that has quantified confidence in the recovery of the ozone hole,” said Susan Solomon, the lead author of the study and the Lee and Geraldine Martin Professor of Environmental Studies and Chemistry at MIT. “We can now say with 95% confidence that the ozone layer is healing, and this is an encouraging example of how global cooperation can solve significant environmental issues.”
The work was led by graduate student Peidong Wang from the Department of Earth, Atmospheric, and Planetary Sciences (EAPS), along with co-authors Susan Solomon and EAPS Research Scientist Kane Stone. The study also included collaborations from various other research institutions. The researchers applied a novel approach, borrowing techniques from climate science, to quantify the recovery of the ozone layer and specifically attribute it to human actions aimed at reducing harmful chemicals.
The Ozone Layer and Its Role
Ozone, a naturally occurring gas in the Earth’s stratosphere, acts as a protective barrier, filtering out harmful ultraviolet (UV) radiation from the sun. This shielding is vital for maintaining life on Earth, as excessive exposure to UV rays can lead to severe health issues, including skin cancer, cataracts, and weakened immune systems.
In 1985, scientists discovered a hole in the ozone layer over Antarctica, which opened up during the southern hemisphere’s spring months (September to December). This ozone depletion allowed more UV rays to penetrate to the Earth’s surface, raising concerns about its potential impact on human health and ecosystems.
The cause of this depletion was quickly identified as chlorofluorocarbons (CFCs) – synthetic chemicals used in products like refrigeration, air conditioning, and aerosol sprays. When released into the atmosphere, CFCs gradually rose to the stratosphere, where they broke down ozone molecules, especially under certain seasonal conditions.
In response to these findings, the Montreal Protocol was drafted in 1987, an international treaty designed to phase out the production of CFCs and other ozone-depleting chemicals. This treaty is often hailed as one of the most successful environmental agreements in history. As a result, global emissions of these harmful chemicals began to decrease, and scientists started to notice some early signs of the ozone layer’s potential recovery.
Early Signs of Recovery
In 2016, Solomon and her colleagues reported the first major signs that the ozone hole was shrinking. Their study indicated that the hole seemed to be smaller in recent years, particularly during September, the peak of the ozone depletion season. However, these observations remained largely qualitative, with large uncertainties surrounding the cause of this recovery. It was unclear whether the shrinking ozone hole was a direct result of global efforts to reduce CFCs or whether it was influenced by natural variability, such as changes in weather patterns, the polar vortex, or phenomena like El Niño and La Niña.
“We knew that ozone levels were improving, but it was difficult to say with certainty if the recovery was due to the decline in ozone-depleting substances, or if it was just driven by natural changes in atmospheric conditions,” said Wang.
The New Study and Statistical Confidence
To resolve this uncertainty, the MIT team adopted a more rigorous, quantitative approach. They employed a technique called “fingerprinting,” which had been pioneered by Klaus Hasselmann and was instrumental in confirming the anthropogenic causes of climate change. Fingerprinting in climate science refers to isolating the specific impact of human activity on the atmosphere, filtering out natural variability.
Solomon and Wang applied this method to ozone recovery. They conducted simulations of the Earth’s atmosphere under various conditions: one where greenhouse gases and ozone-depleting substances increased, and others where only one of these factors changed. By comparing these simulations, the team identified distinct patterns, or “fingerprints,” of ozone recovery driven specifically by the reduction in CFCs and other ozone-depleting substances.
The team then compared these simulated fingerprints to actual observational data from satellites, covering the period from 2005 to the present. The results were striking. As the years progressed, the fingerprint of ozone recovery grew clearer, peaking in 2018. By this time, the researchers could confidently conclude that, with 95% certainty, the observed recovery of the ozone layer was directly attributable to the reduction in ozone-depleting substances.
“This is a major step forward because we can now statistically distinguish the human influence on ozone recovery from the natural variability in the atmosphere,” Wang explained. “We are able to say that the observed changes in the ozone layer are not just the result of random natural fluctuations but are significantly due to human efforts.”
Implications for the Future
The findings of the study suggest that, if current trends continue, the ozone layer will continue to heal, and the ozone hole over Antarctica may eventually close completely. Scientists believe that by 2035, we could see a year when there is no depletion of the ozone layer over the Antarctic, and the hole could be a thing of the past.
“This is a great example of how international cooperation and adherence to environmental treaties can lead to tangible results,” Solomon said. “By following through with the Montreal Protocol, we are not just protecting the ozone layer; we are also showing that we can take on global environmental challenges and make a real difference.”
In addition to the health benefits that come with reducing exposure to UV radiation, the healing of the ozone layer could also have important implications for global climate systems. The ozone layer plays a key role in regulating the Earth’s climate, and its recovery could lead to a more stable and predictable atmospheric system.
Furthermore, the study serves as a hopeful message for the future. It shows that environmental problems can be tackled effectively through science, policy, and global cooperation. Solomon emphasized that this study demonstrates the power of human agency in addressing environmental crises, offering hope for solutions to other pressing issues, such as climate change.
“It shows that we can actually solve environmental problems,” Solomon concluded. “We’ve done it before, and we can do it again.”
The recovery of the Antarctic ozone layer is not just a victory for the environment but a triumph of collective human effort. The study reinforces the importance of continued international cooperation and adherence to environmental agreements in addressing global challenges. If this recovery continues, future generations could see a fully healed ozone layer, a testament to the success of global environmental efforts and a lasting legacy for years to come.
More information: Peidong Wang, Fingerprinting the recovery of Antarctic ozone, Nature (2025). DOI: 10.1038/s41586-025-08640-9. www.nature.com/articles/s41586-025-08640-9