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]]]]]]]]] OZONE SCARE GENERATES MUCH HEAT, LITTLE LIGHT [[[[[[[[[
By S. Fred Singer (9/8/88)
[From The Wall Street Journal, 16 April 1987, p. 30:3]
[Kindly uploaded by Freeman 10602PANCZ]
Another ozone scare appears to be upon us, and it could be
just as misleading as the one that led Congress to cancel the SST
prototype in 1971. Following congressional testimony last month
that dangerous melanoma skin cancers had increased 83% in the
past seven years, press reports implied that the increase was the
result of the destruction of the ozone in the atmosphere, which
allowed more ultraviolet radiation to reach Earth. The ozone
supposedly was destroyed by widely used chemicals known as
chlorofluorocarbons (CFCs).
But there is no reliable evidence that the total amount of
ozone has decreased, and any increase in the incidence of
melanoma, the most serious type of skin cancer, must therefore
involve other causes. Indeed, oncologists have proposed many
such causes: viruses, genetic predisposition, environmental
carcinogens, population shifts to the Sun Belt, changes in life
style, earlier detection of melanomas, and even diet.
In addition, there has been only a modest increase -- well
explained without assuming any change in ozone -- in the
incidence of non-melanoma skin cancers. (These cancers, which
are easily cured, are 20 times more frequent than melanomas)
Non-melanoma cancers, such as those removed from the Reagans,
seem directly related to exposure to ultraviolet rays and would
be expected to increase markedly if ozone were destroyed.
It is true that over the past several years, localized and
temporary decreases in ozone levels have been observed high in
the Antarctic stratosphere during mid-autumn. But these findings
do not prove that CFCs are destroying ozone. A complete
explanation is not yet available; in the presence of the world's
lowest temperature, atmospheric chemistry may be quite unusual.
Some scientists believe that ozone is not lost at all but simply
moves about as atmospheric motions bring in ozone-depleted air
for a few weeks. In any case, ozone changes over the Antarctic
cannot affect melanoma rates in the U.S.
This is not the first ozone scare. Before 1970, it was
generally believed that the creation and destruction of ozone in
the stratosphere -- where most of it is located -- was caused by
only by solar ultraviolet radiation. But then the political
controversy over the construction of prototypes for a supersonic
transport aircraft focused attention on potential environmental
effects of an eventual fleet of 500 SSTs.
According to then-prevailing scientific wisdom, water vapor
from the SST exhaust was supposed to destroy ozone, admitting
more ultraviolet radiation to the earth's surface. It was soon
discovered, however, that water vapor doesn't destroy ozone very
effectively. Attention next focused on nitrogen oxides (NOX),
which also were produced by SST fuel combustion and were said to
be a much more potent ozone-destroyer than water vapor. Based on
our present knowledge, however, while NOX would lead to a modest
destruction of ozone in the upper stratosphere, it would increase
the amount of ozone in the lower stratosphere. So much for the
accuracy of predictions.
The latest candidate as an ozone destroyer -- and the one that
is causing concern today -- is chlorine, and its most important
stratospheric source may be the CFCs. These are inert gases used
mainly in aerosol cans and refrigeration, and as blowing agents
for plastic foams and as solvents. Chemically stable, they
survive in the lower atmosphere, but are finally broken down by
solar ultraviolet radiation when they percolate into the
stratosphere, releasing chlorine.
The U.S. Environmental Protection Agency has estimated that
constant growth of CFC use at an annual rate of 2.5% could remove
sufficient ozone to cause an additional one million non-melanoma
skin cancers over the lifetime of the present U.S. population.
These numbers look huge until they are compared with the current
U.S. rate of about 500,000 new cases each year. Even so, the EPA
numbers are only upper limits, and about as likely as the lower
limits, which are zero. The relation between ozone depletion and
skin-cancer increases is based on a simple-minded statistical
analysis that neglects all factors except the variation of solar
ultraviolet radiation with geographic latitude.
With this fragile scientific base, and many questions still
unanswered, the U.S. has taken the lead on international controls
of CFCs, supported mainly by the Scandinavian countries -- which
do not manufacture CFCs. Opposed are Britain, France, Japan and
the East Block -- which do manufacture CFCs and would be forced
to close down existing facilities if an international production
phasedown is agreed upon. Because skin cancers occur mainly
among Caucasians, the Third World has not gotten too excited
about CFCs, even though ultraviolet intensity is greatest near
the equator.
DuPont has already developed substitutes -- albeit more costly
ones -- to comply with the self-imposed U.S. ban on the use of
CFCs in aerosol cans that went into effect in the mid-1970s.
Substitution for spray cans is simple -- compressed hydrocarbons.
But it is costly for refrigerators and other industrial uses.
U.S. production of CFCs today is only half of its 1974 peak of
400,000 tons, but is rising. Non-U.S. production has been
increasing slowly since 1974 and now stands at 600,000 tons a
year.
Plans to phase out CFCs internationally have made substantial
progress, spearheaded by the U.S. State Department. In 1985, the
Vienna Convention for the Protection of the Ozone Layer created a
framework for a protocol to control CFCs. The U.S. Senate
ratified this convention last July [1986]. Having achieved this
first step, the enthusiasts for international controls, backed by
the EPA and assorted environmental groups, are now pushing for a
protocol to phase out, or at least freeze, CFC production
world-wide.
Even if such controls are rejected by the world community,
there are likely to be consequences in terms of U.S. legislation
for further unilateral controls, plus pressure on friendly
governments to go along with the U.S. Such pressure may lead to
trade policies that could harm international relations. These
economic and political costs will have to be weighed against the
risk of damage from a possible reduction in ozone.
The well-established greenhouse effects of the CFCs that could
lead to climate warming need to be included in the risk
assessment. However, their effects are small compared with those
of carbon dioxide from the burning of fossil fuels, and no one is
suggesting that we stop energy production and freeze in the dark.
One final note: As chemical calculations improve, the
projected decreases in ozone caused by CFCs have shrunk. The
National Academy of Sciences issued reports in 1979, 1982 and
1984 projecting ozone losses after the year 2000 of 18%, 7% and
about 3%, respectively, from present levels. Furthermore, human
activity will continue to generate pollutants such as carbon
dioxide, methane and nitrogen oxides, which will counteract the
destruction of ozone by CFCs. It may well turn out that the
effects will cancel each other out, leading to little net change
in total ozone.
---------------------------------
Mr. Singer, an atmospheric physicist at George Mason
University, in 1970-71 headed a committee that evaluated the
environmental effects of the SST for the Department of
Transportation.
* * *
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