Ifda dossier 47, May/June 1985

We thought we knew
We thought we knew about nuclear war. The bombs. The
pulse of light, the blast, heat and radiation. The fallout.
The devastation and death.
We knew about Hiroshima and Nagasaki. Major scientific
studies had reported what the effects of nuclear war would
be on ~coole. cities and countries. From evervthine we
had seen. kadand been told, we thought we understood
the terrible consequences of nuclear war.
And then. late in 1983, new findings were relca.ud which
made most previous assumptions about nuclear war-
appalling as they were-seem optimistic.
The new threat of Nuclear Winter
The findings suggest that nuclear war, even if it occurred
in summer, could trigger a catastrophic nuclear winter.
transforming the Earth into a darkened, frozen planet. The
very survival of many life forms, including the human
species, could be endangered.
All during the nuclear age. we have been totally ignorant
of what may beone of the most significant consequences
of nuclear war. Although there are still many uncertainties,
the new findings change much of what we thought
we understood about nuclear war. For example, it is now
apparent that because of the deadly effects of the cold and
(he dark, a nuclear first strike of sufficient magnitude to
trigger the nuclear winter could prove suicidal for the aggressor
nation, even without retaliation.
How did we
come to know?
In 1980, articles were commissioned by the Editor of
Ambio, theenvironmental journal of the RoyaJ Swedish
Academy of Sciences, for a special issue on the human
ind ecological consequences of nuclear war. Published
in June 1982. the issue included an article by Dr. Paul J
Cmtzen and Dr. John W. Birks which orescnted - calcula- ~-
tions on the extent to which the immense quantities of
smoke and soot from forests and cities set ablaze in a
nuclear war could block sunlight from the Earth's surface.
Noone had examined these effects indetail before.
Earlier. Dr. Carl Sagan and other observers studying
Mars learned hat heavy dust storms block sunlight and
cool the surface of that planet.
The Martian observations and the Cmtzcn-Birks paper
led scientists R.P. Turco. 0.0. Toon. T.P. Ackerman.
J.B. Pollack, and Carl Sagan, now known as the TTAPS
group from their initials. toconduct a study on the atmospheric
effectsof soot and dust from a variety of nuclear
war scenarios, using computer simulations. Under the
auspices of the Conference on the World After Nuclear
War. scientific meetings involving some 80 scientists
from seven countries were held in Cambridge. Massachusens,
April 22-26, 1983. There was agreement on the
basic premises of TTAPS. Biologists then reached a consensus
on the effects of nuclear winter on life on Earth.
A paper based on the TTAPS study and a companion
paper developed by a group of biologists headed by Dr.
Paul R. Ehrlich were published in the December 23, 1983
issue of 5cience (pp. 1283- 1300).