he chemist F. Sherwood Rowland is one of the few people in history about whom it can accurately be said: he helped save the world. In 1972, Rowland, a chemist at the University of California-Irvine, attended a talk on the compounds known as chlorofluorocarbons. At the time, these were being used as refrigerants, cleaning agents, and propellants in aerosol cans, and they had recently been detected in the air over the Atlantic. CFCs are unusually stable, but it occurred to Rowland that, if they were getting blown around the world, at very high altitudes they would eventually break down. He and one of his research assistants began to look into the matter, and they concluded that in the stratosphere CFCs would indeed dissociate. The newly liberated chlorine atoms would then set off a chain reaction, which would destroy the ozone layer that protects the earth from ultraviolet radiation.

Industry groups ridiculed Rowland’s findings-Aerosol Age accused him of being a K.G.B. agent-but other scientists confirmed them, and Rowland pressed for a ban on CFCs. As he said, ‘What’s the use of having developed a science well enough to make predictions if, in the end, all we’re willing to do is stand around […]