**The ozone layer above the Antarctic is healing thanks to global efforts to reduce ozone-depleting substances such as chlorofluorocarbons (CFCs), an MIT study has found.**
Lying in the stratosphere, the ozone layer absorbs a portion of the radiation from the sun, preventing it from reaching the planet’s surface. That radiation can cause skin cancer, cataracts and damage to plants and marine life if it reaches the Earth’s surface unimpeded.
In 1986, scientists led expeditions to the Antarctic, where they gathered evidence that a growing hole in the ozone layer was caused directly by broad use of CFCs – chemicals that were then deployed in refrigeration, air conditioning, insulation and aerosol propellants.
The following year, those revelations led to the drafting of the Montreal Protocol – an international treaty that aimed to phase out the production of CFCs and other ozone-depleting substances globally, in hopes of healing the ozone hole.
While signs of ozone recovery have been observed in the past, the new MIT study is the first to show, with high statistical confidence, that this recovery is due primarily to the reduction of ozone-depleting substances, as opposed to other influences such as natural weather variability or increased greenhouse gas emissions to the stratosphere.
“There’s been a lot of qualitative evidence showing that the Antarctic ozone hole is getting better. This is really the first study that has quantified confidence in the recovery of the ozone hole,” said study author Susan Solomon. “The conclusion is, with 95% confidence, it is recovering. Which is awesome. And it shows we can actually solve environmental problems.”
The researchers started with simulations of the Earth’s atmosphere and generated multiple ‘parallel worlds’, or simulations of the same global atmosphere, under different starting conditions.
To prove their theory, they ran simulations under conditions that assumed no increase in greenhouse gases or ozone-depleting substances. Under these conditions, any changes in ozone would be the result of natural weather variability. They also ran simulations with only increasing greenhouse gases, as well as only decreasing ozone-depleting substances.
While the hole in the ozone layer expands and contracts due to seasonal variability, Solomon now anticipates that soon there will be a year when the hole stays entirely intact before hopefully staying shut for good.
In April last year, environmental researchers found that illegal refrigerant gases, including CFCs, [are still being smuggled](https://eandt.theiet.org/2024/04/08/refrigerant-gases-banned-their-climate-warming-impact-are-being-smuggled-europe) into Europe by organised criminal gangs attracted by high profits and weak law enforcement efforts.