discovery by scientists of the Antarctic ozone hole in 1985. In January 1986, EPA initiated a series of workshops designed to build an international scientific consensus supporting the need to control the use of CFCs. In the same year, DuPont announced that its scientists had determined that CFCs were the most likely cause of ozone depletion. These events persuaded American officials of the need for decisive international action. When negotiations on a protocol to the Vienna convention for controlling CFCs resumed in December 1986, the United States adopted a firm position, calling for an international treaty not only freezing production of CFCs but also reducing production and consumption.

Following extensive and complex negotiations, the Europeans, whose earlier opposition to a cutback in production had prevented agreement in Vienna, moved closer to the U.S. position. They were persuaded to do so by three factors: the weight of scientific evidence, pressures from their own domestic environmental groups, and the fear that, in the absence of a treaty, the United States might take unilateral action to impose trade sanctions. While compromises on several controversial points proved sufficient to gain Japanese and Soviet adherence, the major developing countries (e.g., China and India) did not become signatories to the Montreal Protocol.

Only after the Montreal Protocol was signed did the full extent of ozone depletion became public: ozone depletion over Antarctica reached a historic high in 1987, and the link to the release of CFCs became a matter of scientific consensus. DuPont responded by announcing that it planned to discontinue CFC production by the end of the century and, in March 1989, 123 countries called for the absolute elimination of production by the same date. A resolution agreeing to totally phase out all production and consumption of CFCs by the year 2000 was adopted by 81 countries in May 1989 at the first governmental review of the Montreal Protocol.

Taking advantage of this momentum, the parties to the Montreal Protocol, meeting at a review conference in London in June 1990, were able to negotiate a series of strong amendments. These amendments accelerate the phaseout schedule for CFCs and halons and add methyl chloroform and carbon tetrachloride to the list of chemicals to be eliminated. Equally important, the amendments establish an international fund to be used to assist developing countries in switching to substitutes for CFCs in the production of refrigerators and air conditioners. On the strength of this



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