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ozone layer (Rowland and Molina, 1974). Concern continued, and
in 1985 scientists detected unexpected seasonal losses in the
stratospheric ozone layer above Antarctica (Farman et al., 1985).
In 1987, these concerns resulted in the Montreal Protocolan
international agreement to reduce by 1998 the production and use of
CFCs, in developed countries, to 50 percent of their 1986 levels
and to freeze halon production at 1986 levels by 1993. By 1988,
research had shown that chlorine from man-made sources, primarily
CFCs and CCs, contributed to the temporary early spring ozone
losses above Antarctica. The Montreal Protocol was amended in 1990
to require a total phaseout of CFCs, halons, and carbon
tetrachloride by the year 2000 in developed countries (2010 in
developing countries). Not all countries have agreed to sign the
Montreal Protocol, however, and this fact, along with the
possibility that some countries may not comply with the agreement,
has caused concern. More than 100 countries with over 67 percent of
the global population and about 10 percent of current CFC
useIndia and China includedhave not yet signed the
The United States has signed the Montreal Protocol. In addition,
the 1990 amendment to the Clean Air Act will further regulate
halocarbons in the United States. Figure 25.2 illustrates how CFC
consumption will decline between now and 2010 because of the new
Clean Air Act amendment.
Besides having a role in ozone depletion, CFCs are also
greenhouse gases. Unlike the other greenhouse gases, which began to
increase during the Industrial Revolution (1850), CFCs were not
introduced until the early
FIGURE 25.1 CFC and halon consumption by
geographic region, 1985.