In September 1987, thirty-one countries, meeting under the auspices of the United Nations Environment Program in Montreal, signed an agreement to protect the earth's ozone layer. The Montreal Protocol was the culmination of a series of events which had been initiated two years earlier at the Vienna Convention for the
Protection of the Ozone Layer. Twenty nations signed the Vienna Convention in September 1985, promising international cooperation in research, monitoring and the exchange of information on the problem. In the two-year period between the meetings much time and effort went into formulating plans to control the problem, with the countries of the European Community (EC) favouring a relatively gradual approach compared to the more drastic suggestions of the North Americans (Tucker 1987). The Environmental Protection Agency (EPA) in the United States, against a background of an estimated 39 million additional cases of skin cancer in the next century, suggested a 95 per cent reduction in CFC production within a period of 6-8 years (Chase 1988). When the Montreal Protocol was signed, participants agreed to a 50 per cent production cut by the end of the century, although that figure is deceptive, since Third World countries were to be allowed to increase their use of CFCs for a decade to allow technological improvements in such areas as refrigeration. The net result turned out to be only a 35 per cent reduction in total CFC production by the end of the century, based on 1986 totals (Lemonick 1987). This was a historic agreement, but certain experts in the field, such as Sherwood Rowland, felt that it is not enough, and that the original 95 per cent proposed by the EPA was absolutely necessary (Lemonick 1987).
The signatories to the Montreal Protocol met again in Helsinki in May 1989. At that time, along with participants from some 50 additional countries, they agreed to the elimination of CFC production and use by the year 2000. Continued reassessment of the issue led to a further meeting of the world's environment ministers in Copenhagen in 1992, at which deadlines for the control of ozone-destroying gases were revised. In most cases—CFCs, carbon tetrachloride and methyl chloroform—production bans were brought forward from 2000 to 1996, but in the case of halons the ban was to be implemented by 1994 (see Table 6.2). HCFCs—widely used as substitutes for CFCs—were to be phased out progressively over a thirty-five-year period ending in 2030. Methyl bromide was added to the list of banned substances, with emissions to be frozen at the 1991 level by 1995 (MacKenzie 1992).
In contrast to their attitudes in the 1970s, the CFC manufacturers responded positively after Montreal to the call for a reduction in the manufacture of the chemical. The DuPont Company, for example, pledged to reduce its output by 95 per cent by the year 2000 (the original EPA suggestion), although the initial search for appropriate substitutes—which included testing for health and environmental effects—was estimated to take up to five years (Climate Institute 1988c). The market for substitutes is large, particularly in Europe, where CFCs were not banned in the 1970s. Although the concern for the supply of energy is no longer at crisis levels, the demand for residential and industrial building insulation remains high, and will undoubtedly rise if energy supplies are again threatened. Since the manufacture of insulating materials accounts for 28 per cent of worldwide CFC production, the search for alternatives received urgent attention. Results have been mixed. DuPont has developed hydrochlorofluorocarbons (HCFCs) as potential replacements for CFCs in the production of polystyrene sheet, which has been used successfully in food packaging, but is not suitable for other forms of insulation since the product loses its insulating ability as the HCFCs break down (Webster 1988). HCFCs are 95 per cent less damaging to ozone than normal CFCs because they are less stable and tend to break down in the troposphere before they can diffuse into the ozone layer. Although they are less harmful, they do have a negative impact on the ozone layer, and, as a result, they too will ultimately need to be replaced. An isocyanate-based insulation foam, in which carbon dioxide is the foaming agent, has produced promising results. It cannot be produced in sheet form, however, and, as a result, its use remains limited to situations where spray-on or foam-in application is possible.
Substitutes are being sought in other areas also. For example a German company has developed a so-called 'green' refrigerator, in which the normal CFC refrigerant is replaced by a propane/butane mixture. Although the mixture has a greater cooling capacity than the CFCs currently used, inefficiencies in the compressor system require attention before the refrigerator can compete with conventional units. Bans on the use of hydrocarbons in domestic refrigerators in some countries will also limit its adoption (Toro 1992). More damaging to the ozone than most CFCs are the halons used in fire-fighting— Halon 1301, for example is ten times more destructive than CFC-11—and replacements are required to meet the 1994 ban on halon production agreed at Copenhagen in 1992. To meet that need, a new gas mixture consisting of nitrogen, argon and carbon dioxide has been developed in Britain. None of these gases damages ozone, and existing fire extinguishing systems can be modified to use the mixture (Tickell 1992). Clearly, CFC manufacturing companies, and those utilizing gases hazardous to ozone, are committed to the search for alternatives, but it may be some time before their good intentions are translated into a suitable product.
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