Slate: It’s still a problem. As of a few weeks ago, the “hole”—which isn’t so much a gap in the ozone layer as an area of seasonal thinning—is even bigger than it was at the height of the ozone panic in the 1980s. (At the moment, it spans a patch of sky almost the size of North America.) That said, the ozone layer is in much better shape today than it would have been had the world not taken decisive action 20 years ago. It’s just that the damage we did in the old days is going to take a long time to heal.
It’s still a problem. As of a few weeks ago, the “hole”—which isn’t so much a gap in the ozone layer as an area of seasonal thinning—is even bigger than it was at the height of the ozone panic in the 1980s. (At the moment, it spans a patch of sky almost the size of North America.) That said, the ozone layer is in much better shape today than it would have been had the world not taken decisive action 20 years ago. It’s just that the damage we did in the old days is going to take a long time to heal.
You might remember that ozone gas—made from triplets of oxygen atoms—helps shield us from the sun’s harmful UV-B rays. Most of it is in the lower stratosphere, roughly six to 30 miles above the Earth’s surface, where it’s created naturally by the interaction of sunlight and regular oxygen. Other gases, particularly those containing chlorine or bromine, can make ozone molecules break apart. Starting in the 1970s, scientists suspected that the widespread use of industrial chemicals might be putting additional chlorine and bromine into the stratosphere. In particular, researchers worried about the chlorofluorocarbons used in fridges, air conditioners, and aerosol spray cans and the halon gases used in fire extinguishers. (Human technology also creates some ozone, but that stuff tends to stay close to the ground, where it causes a range of health issues.)
By the mid-1980s, researchers knew that ozone concentrations were decreasing around the world, threatening humans with an increased incidence of skin cancer and eye cataracts and endangering plants and other kinds of animals. In 1985, following several years of U.N.-sponsored meetings, 21 nations formally agreed to cooperate on researching and monitoring the issue. It came to a head two months later, however, when a team of British researchers showed that a huge “hole” had appeared in the ozone layer above the Antarctic. What had been a predicament now started to seem like an emergency.