to the ozone layer did not have much effect on uses that were much more central to the industrial economy: food refrigeration, ambient air conditioning, and electronic manufacturing solvents. (The knowledge that CFCs account for a significant proportion of the human contribution to the greenhouse effect—about 25 percent by the mid-1980s—also did not have much effect.)

Not much effect, that is, until 1985 and the discovery of the ozone hole over Antarctica. Within two years' time, the scientific community agreed that CFCs were the most likely culprit; officials at DuPont, which produced 25 percent of the world's CFCs, declared the company's intent to phase out CFC production over the next decade and a half; and an international protocol was signed at Montreal, in which signatory countries declared their intention to cut CFC production and consumption in half by the end of the century (Benedick, 1989a, b; U.S. Office of Technology Assessment, 1988; Haas, 1989).

The lessons of this story about CFCs and the ozone hole are several. On the positive side, the rapid response of the scientific, industrial, and policy-making communities to the discovery of the ozone hole over Antarctica is reassuring proof that international agreements in response to global change are in fact possible. That the Montreal Protocol and the later, even stronger London amendments to it could be signed even in the absence of environmentally benign alternatives to the CFCs suggests people's perception of how serious and urgent the problem had become, but also their faith—encouraged by DuPont's actions—that alternatives would in fact be available by the time the agreement's deadline fell due. Indeed, the Montreal Protocol is a paradigmatic case of a quick technical fix, in which people respond to the environmental problems of a particular substance by finding (or hoping to find) a technology that can be used for exactly the same purposes without requiring any fundamental change in human economies or societies.

And that suggests some of the less reassuring lessons of this story. Refrigeration and air conditioning have today become so embedded in the American way of life, and in the ways of life of many people the world over, that it is hard to imagine modern food supplies and urban life styles without them. The very form of the post-World War II city, with its tall office buildings, fixed windows, and energy-intensive controlled climate systems, presumes a significant commitment to refrigeration and cooling. Almost no one has responded to the ozone hole by suggesting a retreat from these fundamental technologies of modern life: al-

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