Geoscience Reference
In-Depth Information
between European nations and negotiations between the United States
and Canada yielded first bilateral treaties and eventually the more broadly
international U.N. Convention on Long-Range Transboundary Air Pollu-
tion, proposed in 1979 and ratified in 1983. As Natural Resources Defense
Council and World Resources Institute founder Gus Speth remembers,
the long-distance impacts of these pollutants on agriculture, species and
their habitats, and water quality challenged environmentalists to think
about air pollution as more than just a local, urban problem.
5
Legally, however, acid rain was little more than a variation on a theme,
and American environmental groups initially sought to tackle the problem
primarily by expanding existing legal mechanisms at home. Because of
their impacts on public health and natural beauty (they reduced visibility),
SO
2
and NO
x
(smog) were forms of air pollution in their own right within
the “antidegradation” framework of the Clean Air Acts of 1967, 1970, and
1977.
6
The identifiable impacts of these gases on water quality and plant
growth via acid rain allowed environmentalists to capitalize on the provi-
sions of the Clean Water Act of 1972 as well, increasing their options as
they lobbied for lower emissions thresholds and prepared lawsuits against
businesses, industry, and government agencies.
7
Meanwhile, these same
identifiable impacts, once publicized, helped to mobilize grassroots sup-
port for litigation and lobbying efforts tackling everything from public
health to the sanctity of America's wilderness areas. In 1990, the amended
Clean Air Act finally incorporated an SO
2
emissions trading scheme—
setting the stage for “cap and trade” approaches to CO
2
— but even before
then, acid rain gave environmentalists both legal and political traction on a
large-scale atmospheric problem without necessitating a wholly new strat-
egy of environmental activism.
8
Acid rain linked environmentalists' ideas about regional air pollution
with concerns over large-scale atmospheric change, but it was the degra-
dation of stratospheric ozone that brought environmentalists around to
the legal protection of the global atmosphere as a whole. Ozone (O
3
) is
an allotrope— that is, a natural structural modification— of oxygen (O
2
),
present throughout the various layers of the atmosphere. In the lower
atmosphere (the troposphere), ozone is both a pollutant and an effective
greenhouse gas. High levels of ozone cause respiratory problems in animals
and can “burn” the leaves of sensitive plants. In the stratosphere, though,
where most of the world's ozone is created and destroyed, the gas absorbs
