Environmental Engineering Reference
In-Depth Information
missing sunspot cycle peak was considered to be
the result of the nuclear tests, and the gradual
increase in ozone in the years following was
interpreted as representing the recovery from the
effects of the tests, as well as the return to the
normal cyclical patterns (Hammond and Maugh
1974).
Although it was not possible to establish
conclusive links between nuclear explosions and
ozone depletion on the basis of these individual
tests, a number of theoretical studies attempted
to predict the impact of a full-scale nuclear war
on stratospheric ozone. Hampson (1974)
estimated that even a relatively minor nuclear
conflict, involving the detonation of 50
megatonnes—equivalent to 50 million tonnes of
conventional TNT explosive—would lead to a
reduction in global ozone levels of about 20 per
cent with a recovery period of several years. He
pointed out the importance of thinking beyond
the direct military casualties of a nuclear conflict
to those who would suffer the consequences of a
major thinning of the ozone layer. Since the
destruction of the ozone layer would not remain
localized, the effects would be felt worldwide,
not just among the combatant nations.
Subsequent studies by US military authorities at
the Pentagon supported Hampson's predictions.
They indicated that, following a major nuclear
conflict 50-70 per cent of the ozone layer might
be destroyed—with the greater depletion taking
place in the northern hemisphere where most of
the explosions would occur (Dotto and Schiff
1978).
Similar results were obtained by Crutzen
(1974) using a photochemical-diffusion model.
He calculated that the amount of nitric oxide
injected into the stratosphere by a 500-
megatonne conflict would be more than ten times
the annual volume provided by natural processes.
This was considered sufficient to reduce ozone
levels in the northern hemisphere by 50 per cent.
Dramatic as these values may appear, they remain
approximations—based on data and analyses
containing many inadequacies. Interest in the
impact of nuclear war on the ozone layer peaked
in the mid-1970s and declined thereafter. It
emerged again a decade later as part of a larger
package, dealing with nuclear war and
climatology, which emphasized nuclear winter
(see Chapter 5).
Supersonic transports and the ozone layer
The planning and development of a new
generation of transport aircraft was well under
way in North America, Europe and the USSR by
the early 1970s. These were the supersonic
transports (or SSTs), designed to fly higher and
faster than conventional, subsonic civil airliners,
and undoubtedly a major technological
achievement. It became clear, however, that they
could lead to serious environmental problems, if
ever produced in large numbers. Initial concerns
included elevated noise levels at airports and the
effects of the sonic boom produced when the
aircraft passed through the sound barrier, but
many scientists and environmentalists saw the
impact of these high-flying jets on the structure
of the ozone layer as many times more serious,
and more universal in its effects.
Supersonic transports received a great deal of
attention between 1971 and 1974, as a result of
Congressional hearings in the United States into
the funding of the Boeing SST, and a subsequent
Climatic Impact Assessment Program (CIAP)
commissioned by the US Department of
Transportation to study the effects of SSTs on
the ozone layer. The findings in both cases were
extremely controversial, and gave rise to a debate
which continued for several years, at times highly
emotional and acrimonious. It was fuelled further
by a series of legal and legislative battles which
ended only in 1977, when the US Supreme Court
granted permission for the Anglo-French
Concorde to land at New York. The proceedings
and findings of the Congressional hearings and
the CIAP, plus the debate that followed, have
been summarized and evaluated by Schneider and
Mesirow (1976) and Dotto and Schiff (1978).
The arguments for and against the SSTs were as
much political and economic as they were
scientific or environmental. They did reveal,
however, a society with the advanced technology
