The Ozone Layer Is On Track for a Full Recovery, Thanks to Global Collaboration Since 1987
Once upon a time, all the countries of the world came together and agreed on a plan to save the planet from a dire threat to life. And it worked. Sounds like a fairy tale, doesn’t it? But it’s a true story.
During the 20th century, a trickle, and then a flood of scientific data and observations showed that something disturbing was going on with the ozone layer, the protective layer in the stratosphere that serves as the planet’s sunscreen, absorbing ultraviolet radiation and keeping most of it from reaching Earth’s surface, according to NASA.
In short, the data revealed that the ozone layer was getting thinner. And in Antarctica, a hole in the ozone layer would open up every year between September and December. And the hole was getting bigger.
The potential consequences were grave. In humans, a depletion of the ozone layer would lead to an increase in skin cancers (and possibly other cancers as well), cataracts and other eye diseases, and weakened immune systems. Other animals would suffer from similar ailments. Increased UV radiation would also affect plant growth, disrupting food webs and potentially reducing agricultural productivity. We really didn’t want to go there.
Read More: Whatever Happened to the Hole in the Ozone Layer?
Saving the Ozone Layer
Scientists scrambled to determine the cause of the hole. In 1974, Mario Molina and Sherwood Rowland published research in the journal Nature that found the culprit was chlorofluorocarbons (CFCs), chemicals widely used in air conditioning, refrigeration, and aerosol sprays. (In 1995, Molina and Rowland, along with Paul Crutzen, won the Nobel Prize in chemistry for this work.)
Molina, Rowland, and many other scientists continued to accumulate evidence as they worked to understand how these chemicals damaged the ozone layer.
In 1986, Susan Solomon, a researcher now at MIT who at the time worked for the National Oceanic and Atmospheric Administration (NOAA), led expeditions to Antarctica, where she and her team confirmed that CFCs were responsible for damage to the ozone layer. The science was clear, and the solution was obvious: ban CFCs.
And that’s just what happened.
In 1987, the world’s nations (eventually every one of them) signed the Montreal Protocol, a treaty that gradually phased out CFCs and other ozone-depleting substances. A 2015 study in Nature Communications found that without the changes brought about by the Montreal Protocol, the ozone hole would have grown by 40 percent by 2013. Instead, it’s shrinking.
In September 2025, the World Meteorological Organization announced that the ozone layer is on track for a full recovery, maybe as soon as mid-century.
Fingerprinting the Villain
Plenty of research has documented the recovery of the ozone layer, but it’s been harder to quantify the factors responsible for that improvement, Peidong Wang, a climate scientist who studied under Solomon at MIT and is now at Stanford, told Discover.
Previous research could not determine how much of the recovery resulted from reductions in ozone-depleting chemicals rather than other factors, such as weather variability due to El Niño, La Niña, or the polar vortex.
However, Wang and colleagues borrowed a technique from researchers studying climate change. Called “fingerprinting,” the method isolates specific climate factors to confirm and quantify the role of human activities in climate change.
When applied to the ozone layer, the results clearly showed that while other factors account for some year-to-year variability in the size of the ozone hole, the actions taken under the Montreal Protocol to reduce ozone-depleting substances are the primary reason for the recovery of the ozone layer. Wang and colleagues published this research in the journal Nature in March 2025.
Hope for Combating Climate Change
When it comes to climate change, the challenges are somewhat different. For one thing, CFCs were made by only a few companies, and it was relatively easy to find alternatives, many of which were produced by those same companies, Wang explained.
But still, he’s hopeful that we can solve the climate change crisis, too.
“My advisor, Susan Solomon, is a very optimistic person, and I think I was kind of affected by her opinion,” he told Discover.
As Solomon put it in her 2024 book, Solvable, “We’ve done it before, and together we can do it again.”
Read More: How the Ozone Layer Evolved and Why It’s Important
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