Ifda dossier 47, May/June 1985

The atmospheric findings
Thestudy showedthat sooty imoke from burningcities,
industrial sites and forests, and dust lofted into the aunosphere
by nuclear ground burstsmight. incertaincircumsiiinces.
JrariiciiJly reduce theamount ofsunlight reaching
the Earth. Computer models were ud to examine a wide
variety of nuclear war scenarios, ranging from 100 to
10.000 megatons (oiie megaton has roughly thc explosive
power ofone million IonsofTNT). Work! nucleararsenali
comprise about 15.000 niegatons. The finding:! indicate
that a5.000 megaton nuclear war (assuming 10,000
explosions and 20 percent of the megatonnage used on
industrial and urban targets) could result in:
dark clouds of soot and dust spreading and coalescing
to cover the Northern Hemisphere within a week or two
and then probably movingdownover the Southern Hemi-
sphere; all but a small percentage of sunlight Mocked
by the dark soot and dust; average 1a:id te.-nperaiu:'es
in the Northern Hemisphere plummcim$ in - 15'C to
-25'C ($'F to - 13T) within a w:ek .:r :WO.
The cold and the dark. exte~tded over weeks or months.
could cause ma&s deaths and eç.tiixiions Similar climatic
effects could result frum a wide variety of nuclear
exchanges. Theueof a small fraction of world arsenaLs
could trtgget ii nucle~r winter if major urbancenters
were hit.
The Conference
These findings were first made public at the Conference
on the World After Nuclear War held in Washington.
D.C. (October 3 1 -November 1, 1983), attended by about
600 people. Dr. Car1 Sagan and Dr. Paul Ehrlich were
the principal speakers. A satellite television link between
scientists at the USSR Academy of Sciencesand scientists
at the Conference in Washington provided independent
Soviet confirmation of the findings.
An Earth darkened, frozen
The Studies indicate that he extended darkness and subfreezing
temperatures could have the following consequences:
photosynthesis dra~ticiilly reduced and food
pritduction in the Northern Hemisphere virtually eliminated:
bodies of fresh water frozen: coasial areas
lashed by extremely violent storms; toxic gases, produced
by fires, poisoning the air; * radiation levels in the
mid-north latitudes double those previously indicated.
Survivors in the Northern Hemispherecould be left fac-
ing extreme cold, hunger, toxic pollutants, water shor-
tages, and weakness from radiation, their societies col-
lapsed around them. Following upon the already
disastrous immediate effects of nuclear war which could
kill or seriously injureabout half the human population,
nuclear winter could threaten the survival of the re
minder. Following the dissipation of the cloud cover,
the returning sunlight could posea new threat to life, for
nuclear war could severely deplete the ozone in the at-
mosphere that shields the Earth from damaging
ultraviolet radiation.
Theextinction of a large fraction of the Eanh'sanimals,
plants and micrwrgmisfm seem inevitable. The scien-
lists concluded that even the extinciion of the human
species could not be excluded.
Major
studies underway
Traditionally. the validity of scientific results is checked
esperimentally . This is clearly impossible in the case of
;he nuclear winter findings. yet there are uncertainties that
need to be resolved through further study.
The findings are being subjected to continuing intense and
detailed review at a numberof research institutionsaround
the world. The U.S. National Academy of Sciences is
conducting a major study. and the issue is being addressed
internationally by the Scientific Committee on Problems
of the Environment (SCOPE) of the International Council
of Scientific Unions, drawing upon scientists from more
than 12countries. includingthe U.S..Canada.theUSSR.
France. the UK, Australia, India. Japan and Hungary.
Hope for positive action
As alarming as the findings are. by their very nature they
bring hope that when people and their governmenu undcr-
stand the full implications of nuclear war, they will act
positively to preserve peace. . .and thereby life on this
planet.
Throughout the nuclear age, arms policy decisions have
been made without knowledge of the potential climatic
ad biological effects of nuclear war. With the releaseof
the scientific findings anti taking into full consideration
the uncertainties involved. a new elobal issue of ereat
urgency has emerged. an issue with the potential to bring
all peoples and nations together in positive action to reduce
the risk of nuclear catastrophe.
You can help
The first step must be the worldwide dissemination of
the scientific findings. You can help. You, your
organization, your government, can help to ensure that
the Earth never experiences the cold and the dark of
nuclear winter. Write to the Center on the Conse-
quences of Nuclear War for video, film and printed in-
formation materials. The Center, established as a
follow-up to the Conference on the World After
Nuclear War, actively cooperates with other orga-
tiow and the media in informing the public and
decision-makers about the long-term climatic and
biological effects of nuclear war.
Center on the Consequences of
Nuclear War
1350 New York Ave., NW, Third Floor
Washington, D.C. 20005
(202) 393-1448