Ozone Hole Is Officially Shrinking, Proof That International Treaties Can Be Effective

Public Domain. A view of Earth's atmosphere from space. (NASA)

New NASA study offers first direct proof that the ozone hole is recovering thanks to the Montreal Protocol treaty and the international ban on CFCs.

For anyone alive and reading the news in the 1980s, the discovery of the “ozone hole” might have garnered a prominent spot in the “things to keep one up at night” list. It was basically the trainer environmental nightmare to prepare us for the specter of global climate change. As the ozone layer acts as a protective blanket against the most harmful wavelengths of ultraviolet light, the so-called (and then-expanding) hole over Antarctica brought with it visions of skin cancer, sunburn, cataracts, and havoc to plants and animals, for starters.

The worry that we could lose this protective layer led to the adoption of the Montreal Protocol on Substances that Deplete the Ozone Layer, which was ratified in 1987 ... apparently, back when everyone still believed in science and chemical companies had less power. The international treaty banned the use of chlorofluorocarbons (CFCs) and related compounds. CFCs are long-lived chemical compounds that eventually rise into the stratosphere, where they are broken apart by the sun’s ultraviolet radiation, releasing chlorine atoms that go on to destroy ozone molecules, as NASA explains. They were used as refrigerants and solvents, and in aerosol sprays and blowing agents for foams and packing materials. The pact was signed by 197 countries; later amendments to the Montreal Protocol completely phased out production of CFCs.

Fast forward to 2018, and NASA has now deemed the treaty a success in staving off the demise of the ozone layer. Using measurements from the agency’s Aura satellite, scientists have been looking at the Antarctic ozone hole’s chlorine over the last several years, watching as the amount slowly decreased. The hole has been trending smaller, but as temperature has an effect on its size, it’s been difficult to claim definitive evidence that it’s actually on the mend.

The new study is the first time anyone accurately measured chlorine levels inside the ozone hole, confirming that the Montreal Protocol is indeed doing its job, says NASA.

Lead author of the study, Susan Strahan, an atmospheric scientist from NASA’s Goddard Space Flight Center in Greenbelt, Maryland, describes the work here and success of the treaty here:

It’s a slow recovery, but recovery it is, and wonderful validation that we can turn back the tide of harm we’re doing to the planet. While the ozone hole is still there, the scientists believe that it will continue to recover slowly as CFCs leave the atmosphere. “CFCs have lifetimes from 50 to 100 years, so they linger in the atmosphere for a very long time,” says Anne Douglass, a fellow atmospheric scientist at Goddard and the study’s co-author. “As far as the ozone hole being gone, we’re looking at 2060 or 2080. And even then there might still be a small hole.”

Now, about that Paris Agreement ...