Twenty-five years ago this month, a small team of scientists discovered that the ozone layer above their Antarctic station was thinning more and more every spring. The layer protects life on earth from the sun’s ultraviolet light. The response to that discovery is a rare, happy environmental morality tale.

In 1996, an international accord banned the use of chlorofluorocarbons, or CFC’s — which were used as refrigerants in air-conditioners and propellants in aerosol spray cans — that were causing the ozone hole. The treaty has phased in slowly. And the hole, gaping widely every spring, is much larger today. But it would be far worse without the protocol, and there is good reason to expect that it will return to pre-1970 levels by 2080.
There is another lesson here, one that has nothing to do with citizen action or international accords or aerosol sprays. The discovery of the ozone hole would have been impossible without paying close, consistent attention to the world around us and having the personnel needed to decipher the results.
As Jonathan Shanklin, one of the scientists who discovered the hole notes, Halley Research Station had continuous ozone data reaching back nearly 40 years. Discovering the ozone hole was to a large extent a matter of processing and correlating that data and being open to the surprising results.
It’s a reminder that good science is patient, observant, careful and continuous. That kind of science — which is especially valuable for understanding climate change — requires long-term commitments in financing and education. It requires the ability to gather data accurately over the years and to educate the scientists who can turn that data into a new awareness of how this world works. That knowledge helped us to make the decision that aerosol sprays and other CFC’s are not worth a yawning void in the springtime Antarctic skies