The 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 and wait for them to come true?” The discovery, in the mid-nineteen-eighties, of an ozone “hole” over the South Pole persuaded world leaders, including Ronald Reagan, that the problem was, in fact, urgent, and a global treaty phasing out CFCs was approved in 1987.
Rowland’s question came to mind last week. At a meeting in Yokohama, the Intergovernmental Panel on Climate Change released its latest update on the looming crisis that is global warming. Only this time it isn’t just looming. The signs are that “both coral reef and Arctic systems are already experiencing irreversible regime shifts,” the panel noted. Composed in a language that might be called High Committee, the report is nevertheless hair-raising. The I.P.C.C.’s list of potential warming-induced disasters—from ecological collapse to famine, flooding, and pestilence—reads like a riff on the ten plagues. Matching the terror is the collective shame of it. “Why should the world pay attention to this report?” the chairman of the I.P.C.C., Rajendra Pachauri, asked the day the update was released. Because “nobody on this planet is going to be untouched by the impacts of climate change.”
Talk about standing around and waiting. As in the case of the destruction of the ozone layer, much of the key research on climate change was completed in the nineteen-seventies. (The first major report on the subject from the National Academy of Sciences was requested by President Jimmy Carter.) And, once again, it’s been clear since that time what needs to be done. Global warming is a product of carbon emissions produced by burning fossil fuels, so, if we want to limit warming, these emissions have to be phased out.