The Melting of 'Nuclear Winter'
By Russell Seitz
"Apocalyptic predictions require, to be taken seriously,
higher standards of evidence than do assertions on other
matters where the stakes are not as great."
---Carl Sagan, Foreign Affairs,
Winter 1983 -84
The end of the world isn't what it used to be. "Nuclear Winter," the
theory launched three years ago this week that predicted a nuclear exchange
as small as 100 megatons ("a pure tactical war, in Europe, say" in Carl
Sagan's phrase), in addition to its lethal primary effects, would fill the
sky with smoke and dust, ushering in life-extinguishing sub-zero darkness,
has been laid to rest in the semantic potter's field alongside the "Energy
Crisis" and the "Population Bomb." Cause of death: notorious lack of
The Nuclear Winter conjecture has unraveled under scrutiny. Yet not
so long ago, policy analysts took it so seriously that there is reason to
examine how the powerful synergy of environmental concern and the politics
of disarmament drove some scientists to forge an unholy alliance with
Madison Avenue. Mere software has been advertised as hard scientific fact.
How did this polarization arise?
In 1982, a question arose within the inner circle of disarmament
activists: Could the moral force of Jonathan Schell's eloquent call to lay
down arms, "The Fate of the Earth," be transformed into a scientific
imperative? Peace-movement strategists wanted something new to dramatize
nuclear war's horrors. As Ralph K. White put it in his book "The Fearful
Warriors": "Horror is needed. The peace movement cannot do without it."
What they got was surreal -- a secular apocalypse.
A 1982 special issue of the Swedish environmental science journal
Ambio considered the environmental consequences of a nuclear war. This
special issue did little to evoke a mass response of the sort needed to
change the course of strategic doctrine. But one article contained the
seed of what would become Nuclear Winter.
Mr. Sagan seized upon an article by Messrs. Paul Crutzen and Steven
Birks that raised the question of a "Twilight at Noon" if the fires ignited
by nuclear holocaust were to convert much of the fuel in both woodlands and
cities into enough soot to enshroud the globe. In the hands of others
their concerns would be transformed into an exhortation.
The chilling climatic impact of this soot can be modeled with existing
software. The paper that resulted came to be known as TTAPS, after the
initials of its authors beginning with Richard Turco and ending with Carl
Audubon Society president Russell Peterson, whose wife was editor of
Ambio, sent the issue to Robert Scrivner of the Rockefeller Family Fund.
Mr. Scrivner convened an ad hoc consortium of foundations and scientific
groups with a bent for disarmament. Cornell astrophysicist and media
personality Carl Sagan assembled a scientific advisory board that drew
heavily from such organizations as the Union of Concerned Scientists,
Physicians for Social Responsibility, the Federation of American Scientists
and the Natural Resources Defense Council. Two-dozen foundations and more
than 100 scientists were recruited.
A BONE-DRY BILLIARD BALL
Nuclear Winter never existed outside of a computer, except as a
painting commissioned by a PR firm. Instead of an earth with continents
and oceans, the TTAPS model postulated a featureless, bone-dry billiard
ball. Instead of nights and days, it postulated 24-hour sunlight at one-
third strength. Instead of realistic smoke emissions, a 10-mile-thick soot
cloud magically materialized, creating an alien sky as black as the ink you
are reading. The model dealt with such complications as geography, winds,
sunrise, sunset and patchy clouds in a stunningly elegant manner -- they
were ignored. When later computer models incorporated these elements, the
flat black sky of TTAPS fell apart into a pale and broken shadow that
traveled less far and dissipated more quickly.
The TTAPS model entailed a long series of conjectures: if this much
smoke goes up, if it is this dense, if it moves like this, and so on. The
improbability of a string of 40 such coin tosses coming up heads approaches
that of a pat royal flush. Yet it was represented as a "sophisticated one-
dimensional model" -- a usage that is oxymoronic, unless applied to Twiggy.
To the limitations of the software were added those of the data. It
was an unknown and very complex topic, hard data was scant, so guesstimates
prevailed. Not only were these educated guesses rampant throughout the
process, but it was deemed prudent, given the gravity of the subject, to
lean toward the worst-case end of the spectrum for dozens of the numbers
involved. Political considerations subliminally skewed the model away from
natural history, while seeming to make the expression "nuclear freeze" a
part of it.
"The question of peer review is essential. That is why we have
delayed so long in the publication of these dire results," said Carl Sagan
in late 1983. But instead of going through the ordinary peer-review
process, the TTAPS study had been conveyed by Mr. Sagan and his colleagues
to a chosen few at a closed meeting in April 1983. Despite Mr. Sagan's
claim of responsible delay, before this peculiar review process had even
begun, an $80,000 retainer was paid to Porter-Novelli Associates, a
Washington, D.C., public-relations firm. More money was spent in the 1984
fiscal year on video and advertising than on doing the science.
The meeting did not go smoothly; most participants I interviewed did
not describe the reception accorded the Nuclear Winter theory as cordial or
consensual. The proceedings were tape recorded, but Mr. Sagan has
repeatedly refused to release the meeting's transcript. (The organizers
have said it was closed to the press to avoid sensationalism and premature
disclosure.) According to Dr. Kosta Tsipis of MIT, even a Soviet scientist
at the meeting said, "You guys are fools. You can't use mathematical
models like these to model perturbed states of the atmosphere. You're
playing with toys."
Having premiered on Oct. 30, 1983, as an article by Mr. Sagan in the
Sunday supplement Parade, the TTAPS results finally appeared in Science
magazine (Dec. 23, 1983). This is the very apex of scholarly publication,
customarily reserved for a review article expounding a mature addition to
an existing scientific disipline -- one that has withstood the testing of
its data and hypotheses by reproducible experiments recorded in the peer-
reviewed literature. Yet what became of the many complex and uncertain
variables necessary to operate the Nuclear Winter model? They were not set
forth in the text -- 136 pages of data were instead reduced to a reference
that said, simply, "In preparation." The critical details were missing.
They have languished in unpublished obscurity ever since.
The readers of Science were still bewildered when, just one week
later, another article by Mr. Sagan -- "Nuclear War and Climatic
Catastrophe" -- appeared in Foreign Affairs. Mr. Sagan argued that,
because of the TTAPS results, "What is urgently required is a coherent,
mutually agreed upon, long-term policy for dramatic reductions in nuclear
In hastening to maximize the impact, Mr. Sagan made mistakes. While
he cited the following passage as coming from a companion piece in Science
that he had co-authored, it did not actually appear in the published
version of that article: "IN ALMOST ANY REALISTIC CASE involving nuclear
exchanges between the superpowers, global environmental changes sufficient
to cause an extinction event equal to or more severe than that of the close
of the Cretaceous when the dinosaurs and many other species died out are
likely. (Emphasis added)." The ominous rhetoric italicized in this
passage puts even the 100 megaton scenario of TTAPS on a par with the 100
million megaton blast of an asteroid striking the Earth. This astronomical
mega-hype failed to pass peer review and never appeared in Science. Yet,
having appeared in Foreign Affairs, it has been repeatedly cited in the
literature of strategic doctrine as evidence.
Rather than "higher standards of evidence," Mr. Sagan merely provided
testimonials. He had sent return-mail questionnaires to the nearly 100
participants at the April meeting, and edited the replies down to his
favorite two-dozen quotations. What became of the hard copy of the less
enthusiastic reports remains a mystery, but it is evident from subsequent
comments by their authors that TTAPS received less than the unanimous
endorsement of "a large number of scientists." Prof. Victor Weisskopf of
MIT, sized up the matter in early 1984: "Ah! Nuclear Winter! The science
is terrible, but, perhaps the psychology is good."
Many scientists were reluctant to speak out, perhaps for fear of being
denounced as reactionaries or closet Strangeloves. For example, physicist
Freeman Dyson of the Institute for Advanced Studies at Princeton was
privately critical in early 1984. As he put it, "It's (TTAPS) an
absolutely atrocious piece of science, but I quite despair of setting the
public record straight....Who wants to be accused of being in favor of
Most of the intellectual tools necessary to demolish TTAPS's bleak
vision were already around then, but not the will to use them. From
respected scientists one heard this: "You know, I really don't think these
guys know what they're talking about" (Nobel laureate physicist Richard
Feynman); "They stacked the deck" (Prof. Michael McElroy, Harvard); and,
after a journalist's caution against four-letter words, "'Humbug' is six
[letters]" (Prof. Jonathan Katz, Washington University).
In 1985, a series of unheralded and completely unpublicized studies
started to appear in learned journals -- studies that, piece by piece,
started to fill in the blanks in the climate-modeling process that had
previously ben patched over with "educated" guesses.
The result was straightforward: As the science progressed and more
authentic sophistication was achieved in newer and more elegant models, the
postulated effects headed downhill. By 1986, these worst-case effects had
melted down from a year of arctic darkness to warmer temperatures than the
cool months in Palm Beach! A new paradigm of broken clouds and cool spots
had emerged. The once global hard frost had retreated back to the northern
tundra. Mr. Sagan's elaborate conjecture had fallen prey to Murphy's
lesser known Second Law: If everything MUST go wrong, don't bet on it.
By June 1986 it was over: In the Summer 1986 Foreign Affairs,
National Center for Atmospheric Research (NCAR) scientists Starley Thompson
and Stephen Schneider declared, "...on scientific grounds the global
apocalyptic conclusions of the initial nuclear winter hypothesis can now be
relegated to a vanishingly low level of probability."
Yet the activist wing of the international scientific estabishment had
already announced the results of the first generations of interdisciplinary
ecological and climatological studies based on Nuclear Winter. Journalists
paid more attention to the press releases than the substance of these
already obsolescent efforts at ecological modeling, and proceeded to inform
the public that things were looking worse than ever. Bold headlines
carried casualty estimates that ran into the proverbial "billions and
This process culminated in the reception given the 1985 report of the
National Academy of Sciences (NAS). Stressing the uncertainties that
plagued the calculations then and now, it scrupulously excluded the
expression "Nuclear Winter" from its 193 pages of sober text, but the
report's press release was prefaced "Nuclear Winter...'Clear Possibility.'"
Mr. Sagan construed the reports to constitute an endorsement of the theory.
But in February 1986, NCAR's Dr. Schneider quietly informed a
gathering at the NASA-Ames Laboratory that Nuclear Winter had succumbed to
scientific progress and that, "in a severe" 6,500-megaton strategic
exchange, "The Day After" might witness July temperatures upwards of 50-
plus degrees Fahrenheit in mid-America. The depths of Nuclear Winter could
no longer easily be distinguished from the coolest days of summer.
As the truth slowly emerged, private skepticism turned often to public
outrage, and not just among the "hawks." Prof. George Rathjens of MIT,
chairman of the Council for a Livable World, offered this judgement:
Nuclear Winter is the worst example of the misrepresentation of science to
the public in my memory."
THE POLITICS OF THE MATTER
On Jan. 23, 1986, the leading British scientific journal Nature
pronounced on the political erosion ofthe objectivitiy vital to the
scientific endeavor: "Nowhere is this more evident than in the recent
literature on 'Nuclear Winter,' research which has become notorious for its
lack of scientific integrity."
But it is by no means solely within the halls of science that
responsibility lies or where redress and the prevention of a recurrence
must be sought. Policy analysts have shown themselves to be the lawful
prety of software salesmen. They seem to be chronically incapable of
distinguishing where science leaves off and the polemical abuse of global-
systems modeling begins. The results of this confusion can be serious
indeed. Doesn't anybody remember the last example of the "Garbage In,
Garbage Out" phenomenon -- the "Energy Crisis"? That crisis also began as
a curve plotted by a computer. But it ended as "The Oil Glut." Factoids,
scientific or economic, have a strange life of their own; woe to the polity
that ignores the interaction of science, myth and the popular imagination
in the age of the electronic media.
To historians of science, the Nuclear Winter episode may seem a
bizarre comedy of manners; having known sin at Hiroshima, physics was bound
to run into advertising sooner or later. But what about the politics of
this issue? Does all this matter? Mr. Sagan evidently thinks it does.
His homiletic overkill has been relentless. An animated version of his
obsolete apocalypse has been added to his updated documentary "Cosmos -- A
Special Edition." This fall, prime-time audiences will watch in horror as
the airbrushed edge of nuclear darknes overspreads planet Earth. Marshall
McLuhan was right on the mark -- with television's advent, advertising has
become more important than products.
What is being advertised is not science but a pernicious fantasy that
strikes at the very foundation of crisis management, one that attempts to
the transform the Alliance doctrine of flexible response into a dangerous
vision. For despite its scientific demise, the specter of Nuclear Winter
is haunting Europe, Soviet propagandists have seized upon Nuclear Winter in
their efforts to debilitate the political will of the Alliance. What more
destabilizing fantasy than the equation of theater deterrence with a global
Gotterdammerung could they dream of? What could be more dangerous than to
invite the Soviets that the Alliance is self-deterred -- and thus at the
mercy of those who possess so ominous an advantage in conventional forces?
The Roman historian Livy observed that "where there is less fear,
there is generally less danger." Until those who have put activism before
objectivity come to apprehend this, nuclear illusions, some spontaneous and
some carefully fostered, will continue to haunt the myth-loving animal that
Mr. Seitz is a Visiting Scholar in Harvard University's Center for
International Affairs. This is based on an article in the fall issue of
The National Interest.