We have moved beyond Cold War definitions of the United States' strategic interests. Our foreign policy must now address a broad range of threats—including damage to the world's environment—that transcend countries and require international cooperation to solve. Vice President Albert Gore, Jr., letter introducing the US State Department's first annual report on the environment and US foreign policy, Environmental Diplomacy (1997).
I started thinking about the subject of this book on September 17, 1987, after reading in the London newspapers that an international agreement had been signed the previous day in Montreal. Twenty-three countries had agreed to cut their production and consumption of CFCs and other ozone-destroying chemicals by half before the end of the century, something I thought would never happen.
The ozone layer is not a layer at all. Ozone molecules, each consisting of three oxygen atoms, only sparsely pack the earth's stratosphere, where concentrations are typically less than one part per million. If you could bring all these molecules down to the earth, however, where they would be compressed by the weight of the atmosphere, they would form a layer—but only a very thin layer, less than a centimeter thick. Though not abundant, ozone is active. And it does something that no other gas in the atmosphere can do; it absorbs the sun's harmful ultraviolet radiation. If ozone became more scarce, more UV-B radiation would reach the earth's surface, damaging living cells. More people would get skin cancers and cataracts, agricultural yields would fall, and, by destroying phytoplankton near the ocean's surface, fish stocks further up the marine food chain would be thinned out. Every country would be harmed. And yet the process of depletion could possibly be halted and even reversed if all countries stopped releasing ozone-depleting chemicals into the atmosphere. This is why our diplomats traveled to Montreal in 1987. They were sent to negotiate an agreement that would control the release of CFCs.
My surprise was in learning that they had succeeded. For though every country would benefit from the protection of the ozone layer, each would benefit whether it contributed to the protection effort or not, and substituting away from CFCs would be costly. In the jargon of economics, ozone layer protection is a global public good. I had been taught, and had come to believe, that cooperation of the kind exhibited in Montreal could not be sustained because of the incentives to free ride.
I was not alone in thinking this way. When I asked colleagues at the LSE, where I was studying for a PhD at the time, what they thought of the agreement, the response