The scandal of nuclear winter.

ADVOCATES OF THE "nuclear winter" theory, such as the popular Cornell astronomer Carl Sagan and his associates in the TTAPS group (Brian Toon, Richard Turco, Thomas Ackerman, and James Pollack), have neglected to explain something: There was no nuclear winter at Hiroshima or Nagasaki.

Winterists actually predict that localized nuclear winters would result from the particularly thick clouds of dust and smoke raised in the target areas shortly after a nuclear attack. Global nuclear winter--which is the part of the prediction most people have heard of--would follow, as the clouds spread over the earth. But since the clouds would thin out as they spread, the effects would be severest on the target areas.

In their August 1984 Scientific American article on nuclear winter, the TTAPS group predicted that a million times less sunlight than normal would reach the ground in these bomb zones. And within "two or three days" there wouled be what they call cquick freezes" below the localized patches of smoke and dust: ...a uniform cloud over the entire globe could reduce the intensity of sunlight reaching the ground by as much as 95 per cent. The initial clouds would not cover the entire globe, however, and so large areas of the Northern Hemisphere, particularly in the target zones, would be even darker.... In the first week or two the clouds would...be patchy.... Within the target zones it would be too dark to see, even at noon... [Emphasis added.]

The West German scientist who is usually credited with the discovery of nuclear winter, Paul Crutzen, also predicts localized severe darkeness. He told the Halloween 1983 press conference on nuclear winter in Washington, D.C., that: Our work indicates that in the area...where the fires would initially occur...hardly any sunlight would be coming through. The sunlight at the ground level would be less than one-millionth of normal. The smoke would then be transported over large areas of the troposphere, and after one month it would cover most of the Northern Hemisphere. [The Cold and the Dark, Norton, 1984.]

The National Academy of Sciences panel on nuclear winter agreed with these specific predictions within a broad range of uncertainty. (It disagreed with the overall TTAPS conclusions, as panel member Jonathan Katz has made clear.) The panel study, (released in December 1984 in response to TTAPS's study, which in turn had been commissioned by the Academy) stated that "widespread dense patches of smoke would make seeing impossible for several days after the nuclear exchange." (Emphasis added.)

Well, it so happens that history has given us a pre-emptive test of these predictions: No one at Hiroshima reported any darkness so intense that it was "impossiblec to see even at high noon. No one reported any local "quick freeze" either. And there were no cases of forstbite. Likewise at Nagasaki, there was no report of pitch-black darkness at noon, no quick freeze, and no frostbite.

These simple facts may be verified by perusing such classic works as Qughterson and Warren's Medical Effects of the Atomoc Bomb in Japan (Mcgraw-hill, 1956), the Defense and Energy Departments' The Effects of Nuclear Weapons (USGPO, 1977 ed., 1983 printing), and Hiroshima & Nagasaki: The Physical, Medical, & Social Effects of the Atomoc Bombings (Basic Books, 1981). This last volume was written by 37 specialists commissioned by the cities of Hiroshima and Nagasaki to complite "all available scientific findings on the nuclear bombing of those cities."

Some might object that it takes thousands of nuclear blasts to create a nuclear winter. But the winterists themselves predict that target areas will freeze in darkness long before the thousands of spreading patches of smoke pool together around the world. Others might suggest that smoke from a modern burning city would be thicker than from a burning Japanese city of 1945. Actually, one would expect the opposite: The flammable paper-and-wood construction then in wide use in the highly congested Japanese cities ought to have made for thicker fire-smoke than modern concrete jungles.

Despite these obvious difficulties, winterists use data on the Hiroshima and Nagasaki fires in all of their models. They assume that the fire characteristics of 1945 Japanese cities are perfectly comparable to those of modern cities. The only adjustment made in their models is for the size of the area burned, which they correlate with the size of the nuclear weapon. They do not relate the local thickness of smoke in any way to weapon size or to the size of the area burned. In other words, nothing in their models would suggest greater smoke thinknesses than those that occurred over Hiroskima and Nagasaki. Yet they predict not only local winters but a global winter after the smoke has spread and thinned to less than one-thousandth of its thickness over the targets.

It is crucial to the winterists' argument, by the way, to show that the fires from the nuclear bombing of cities will cause sufficient smoke to trigger a nuclear winter. The danger of forest and brush fires has been demolished by the painstaking findings of the Pacific-Sierra Research Corp. (see the August 2 issues of Science), now accepted by the original nuclear-winter theorist, Paul Crutzen.

Not only did Hiroshima and Nagasaki fail to produce anything suggesting a nuclear-winter effect, neither has any other comparable recorded event. The National Academy panel tried to defend the winter concept by considering the "Tunguska event," a meteor or comet that exploded a few miles above a siberian in the summer of 1908, generating forces equivalent to those of a seven-megaton hydrogen-bomb explosion. But at Tunguska there was no intense darkeness at noon, quick freeze, and no frostbite, according to the many early eyewitness reports collected by Leonid Kulik and other scientists.

The National Academy report also cites the massive fire-bombing raids over 54 major German and Japanese cities in World War II. firestorms similar to Hiroshima's erupted in some cities hit with conventional incendiary bombs, such as Dresden and Hamburg, and massive fires blazed in others. Yet there was no daytime blackout, and no deep freeze. The Academy report indicates that the sun was blotted out as if by heavy overcast in Hamburg the day after the nightime bombing, but people certainly were able to see. And apparently the smoky overcast cleared by the second day.

The Hiroshima-Nagasaki argument is not the only critical objection to the nuclear-winter theory. Others are outlined below. But it is a good illustration of the nuclear-winter scandal, which is that a number of prestigious scientists have used their standing to promote, for political reasons, a theory that cannot be justified scientifically.

Obviously no full-scale test of the nuclear-winter theory can be performed, since such a test would entail blowing up a considerable portion of the world. Still, it is possible to carry out a responsible scientific investigation by testing parts of the theory, detail by detail, making careful extrapolations only where unavoidable. In order to qualify as science, however, such an investigation would have to bow to such hard facts as became available. By contrast, the nuclear-winterists have persistently ignored, evaded, and even suppressed evidence that contradicts their theory. Moreover, they have tried to con the public into believing (falsely) that nuclear winter has widespread scientific support. And the broader scientific community, on the whole, has been too meek or simply too naive and inexperienced to take effective to counter the winterists.

SAGAN AND HIS ALLIES claim there is growing scientific consensus on nuclear winter. What they fail to mention is the extraordinary publicity campaign that went into artfull constructing the appearance of a consensus, the growing scientific skepticism toward their theory, and the mounting criticism of their tactics.

The nuclear-winter theory was launched intially by the environmentalist movement. It all started with a request from the Swedish environmentalist magazine Ambro to West german atmospheric chemist Paul Crutzen to write an article on the ecological effects of nuclear war. In early 1982, Crutzen hit upon the idea that smoke from nuclearignited fires could drastically alter the climate of the world.

Copies of Crutzen's starling article (co-authored by John Birks, an American) reached the United States even before its publication in Sweden. George Carrier, the Harvard mathematician in charge of the National Academy of Sciences committee studying nuclear war, asked Carl Sagan and his TTAPS team to study crutzen's work. (In other words, the Academy study spawned TTAPS and Nuclear winter, not the other way around, as is widely believed.) Soon after, Richard Turco (the second T in TTAPS) realized that smoke from city fires was more important than smoke from forest and grass fires, and he did some calculations. He came up with a severe freeze blanketing the Northern Hemisphere and dubbed it "nuclear winter."

At this point, Sagan tried and failed to convince the scientific heads of the NASA Ames Research Center (where three of the TTAPS members work) to sponsor, semi-officially, a nuclear-winter presentation to a scientific conference late in 1982. Coming with the appearance of endorsement by the U.S. Government, nuclear winter would have been a bombshell story. The space-agency chiefs, however, refused to give TTAPS a platform, pointing to the scientific inadequacies of the winterist models.

Undaunted by such criticism, Sagan, on several occasions during the summer and fall of 1982, met with leaders of the National Audubon Society and the Rackefeller Family Fund and various environmental activitsts to plan a major publicity campaign to promote the nuclear-winter theory. Sagan also suggested that these groups sponsor a private meeting of selected friendly scientists to hastily "peer review" the TTAPS work and, apparently, to rubber-stamp its conclusions. This would help forestall future criticism that the nuclear-winter theory had not been validated by the scientific community.

The meeting was held on April 22-23, 1983, at Cambridge, Massachusetts (as was a second conference, April) 25-26, on the biological effects of nuclear winter). But apparently it did not work as planned: A number of the scientists whom Sagan and company had hoped would be receptive apparently were quite critical of the theory. For examople, the skeptical statement from the unfortunate Soviet scientist quoted at the beginning of this article came from that meeting, according to Russell Seitz, an MIT-trained physicist, who heard it from MIT's Kosta Tsippis. Word of the revolt eventually leaked out, but it got little attention, allowing Segan and company to claim there was "general" agreement. Indeed they repeatedly cite this meeting as some sort of implied endorsement of their conclusions.

After the initial meetings between Sagan, Audubon, et al., the Kendall Foundation wich funds many environmentalist effots, put up $80,000 to hire the Washington, D.C., public-relations agency of Porter, Novelli and Associates to begin a media blitz., which ended up costing $100,000. Long before the first paper on nuclear winter appeared in a refereed scientific journal (Science, December 23,1983), a popular article by Sagan appeared in the large-circulation Parade magazine. Other winter advocates published articles in other popular magazines. Sagan, along with population-bomber Paul Ehrlich, promoted the theory on The Phil Donahue Show. Professional artists were hired to exaggerate nuclear-freezing gloom-and-doom n full-color paintings for mass publication. And the winterists--still before airing the theory in any scientific journal--held a gigantic Washington press conference with more than one hundred reporters in attendance and featuring "Moscow link" to top Soviet officials and scientists, helpfully televised by the Soviet government. All this, plus international tensions in Beirut and Grenanda, helped to "heighten the dramatic perceptions" of the nuclear-winter threat to mankind, according to Porter, Novelli chairman Jack Porter.

Radical activists, lobbying groups, and special interests jumped on the nuclear-winter bandwagon. A partial list includes: Common Cause, Friends of the Earth, the Institute for Policy Studies (through its bankroller, the Field Foundation), International Physicians for the Prevention of Nuclear War (which is co-chaired by a Soviet official, Yevgeny Chazov, who sits on the Central Committee of the Communist Party of the Soviet Union), Physicians for Social Responsibility (affiliated with the preceding group), Planned Parenthood, Ralph Nader, Scientists against Nuclear Arms, the Sierra Club, the UN Association of the U.S., the Union of Concerned Scientists (of anti-Star Wars fame), and Zero Population Growth.

Sagan hit the college lecture circuit--as well as the campaign trail for Walter Mondale in 1984 and has been stumping for nuclear winter and against Star Wars ever since.

Scientific reaction to the winterists' publicity tactics and their disingenuous claims to have the support of the scientific community has been more censorious than most laymen realize. Criticisms of the winterists received little major media attention, at least partly because many of the more responsible critics have made their points quietly.

Physicist John Maddox, editor of the prestigious British scientific journal Nature, did take the TTAPS authors to task in the September 27, 1984, issue of his magazine: On such a matter, certain to stir the public imagination, it seems to me improper that the results of calculations should be published even in sober language without a warning to all potential readers of the pitfalls there must be. This is doubly unfortunate when, as on this occasion, a purportedly scientific publication is so fully amplified by popular articles, first in parade...

Howard Maccabee, past president of Docotors for Disaster Preparedness, points out in the May issue of Reason magazine: This sequence of events--a publicity campaign paid for and launched before the publication and circulation of a scientific study--is very unusual. In fact, most scientists agree that this type of arrangement is destructive of the goals of honest inquiry and more consistent with attemps at stock-market manipulation or disguised political purposes.

MIT arms-control advocate George Rathjens is an ally of Segan's in the fight against Star Wars. Yet he has charged that winterists suppress research contradicting the winter theory because "people don't want it to be dis-proved." Rathjens told an audience on the Berkeley campus on October 3, 1984, that winterists see the winter idea "as a tool for fighting pernicious public policy" (i.E., President Reagan's).

Russell Seitz of Harvard (who reported the quotation from Vladimir Aleksandrov at the head of this article) has spent many hours tracking down the history of the nuclear-winter movement. He announced his findings publicly at

a Heritage Foundation symposium on nuclear winter on May 21, 1985. He charged, for instance, that Sagan and company bent some established rules of the scientific community in order to speed up publication of TTAPS's seminal December 23, 1983, article in Science--the first thorough presentation of the physical science behind nuclear winter and the first in a "refereed" journal. A refereed journal in one that submits a new article to review by several scientists in the relevant fields, who must attest to its scientific value before publication. Sagan, claims Seitz, in an apparent attempt to influence and speed up Science's decision to publish, sent in his own "reviews." These consisted of about two dozen favorable reports, selected by Sagan out of nearly one hundred he had solicited, many of which may have been far more critical than those he sent Science. Moreover, Seitz claims, Sagan asked a number of allies to write to Philip Abelson, then the editor of Science, urging him to speed up publication.

Science is an interdisciplinary rather than a specialized journal. Normally a broad-ranging review and summary article--such as the TTAPS article--when published in such a journal does not include detailed documentation of all the new science on which it is based. That documentation is first published by the authors in a more specialized journal and thereby subjected to amore rigorous review process. The summary article will then carry footnotes to the specialized articles. These specialized articles are particularly important because the details they include allow other scientists to replicate the experiments or models on which the authors are basing their conclusions. Contrary to this normal procedure, key assertions of the TTAPS article were footnoted to articles " in preparation," which, in the two and one-half years since, have never been published. Thus, not only may Sagan and company have tried to improperly influence Science's review process, they sidestepped the more basic review process on which journals like Science normally depend.

Probably the most unsettling of Seitz's charges was that the TTAPS group has suppressed references to papers by some of its own members contradicting its nuclear-winter claims. The papers, beginning with NASA Reference Publication 1058 of January 1980, by Toon, Turco, and Pollack, show that the dumping of hundreds of millions of tons of soot directly into the stratosphere by a fleet of supersonic transport (SSTs) would result in a trivial temperature drop of "less 0.01 K" (one-fiftieth of one degree Fahrenheit). The analyses all use the same scientific models of the earth's climate that were used in the nuclear-winter studies. When Seitz told this to Academy panelist and Havard geophysicist Michael McElroy, McElroy responded: "They seem to be working both sides of the street."

For the first Cambridge meeting, Seitz reports, Sagan had asked some of his politically sympathetic colleagues among the nation's leading physicists to form a panel to review the winter theory at the end of the conference. The panel included Victor Weisskopf and Philip Morrison of MIT; Princeton's eminent theoretician Freeman Dyson; and Carson Mark, formerly of the Los Alamos Scientific Laboratory. Despite these physicists' leftward leanings, they could not accept what they heard. "The science is terrible," Weisskopf told Seitz. "But perhaps the psychology is good," he added hopefully.

"Not a bet I'd want to make," was Morrison's reaction to the validity of nuclear winter. Sagan is a former student of Morrison's, and both serve on the national council of the Federation of American Scientists, which is well known for its anti-nuclear stance.

Yet these and some other scientists have refrained from making a public issue of their criticism of nuclear winter. Their reluctance seems to be at least partly explained by fear of public reaction. As Dyson remarked: "Frankly, I think it's an absolutely atrocious piece of physics, but I quite despair of setting the public record straight. . . . Who wants to be accused of being in favor of nuclear war?"

Despite the mixed reaction of those who attended the first Cambridge conference, the seminal December 23, 1983, physical-science article in Science has been to some degree credited to that conference. Sagan and company have repeatedly implied that the scientists who attended the April 22-23 conference generally approved of the theory as later presented in the article.

That same issue of Science also carried an article on the biological implications of nuclear winter. Authorsip of the biological article was attributed to the scientists who attended the April 25-26 Cambridge conference for biologists, organized by Paul Ehrlich. The article is essentially a summary of that conference. But the scientists in attendance were given only the worst-case scenarios for nuclear winter: the largest temperature drops over the longest duration, etc. Because no review of the physical science of nuclear winter was permitted at the biologists' meeting, the biologists had to work with what they were given. The result was that their response and the resulting Science article grossly exaggerated the biological effects of nuclear winter, predicting mass extinctions and the end of agriculture, photosynthesis, and possibly man himself. As Cambridge attendee Michael McElroy told Seitz: "They stacked the deck." He added: I think that [the TTAPS biological-effects paper in Science] was absolutely atrocious. I mean it was not science at all. It was emotionalism carried to an extreme. . . . the conclusions are reached in advance of any consideration of the evidence. And individuals who contributed to that, as far as I can see, did not do so critically but did so with a view--and I hesitate to say this--but with a view that it was a political document rather than a scientific document."

Though few such scathing criticisms have been made publicly, scientists are increasingly willing to challenge the nuclear-winter propaganda. When Sagan began making unqualified public references to the December 1984 National Academy report as vindicating TTAPS, the response was swift. "Carl Sagan is wrong," retorted Washington University physicist Jonathan Katz, co-author of the Academy report. Writing in the New York Times of January 5, 1985, Katz stressed that the Academy report "did not endorse the conslusion of the 'TTAPS' report." Rather, the Academy report said the uncertainities in nuclear-winter calculations are so great that a definitive conclusion cannot be reached at this time.

Nature editor Maddox, writing in the March 1, 1984, issue, criticized policymaking based on nuclear winter as premature, since the theory is "not yet established." He ruged that "talk of some of the consequences of nuclear warfare had better be postponed until the underlying assumptions are better understood."

The TTAPS authors replied in the September 27 issue that their findings "evolved from, and were partly calibrated by," 1) some 12 years of research on the dust storms of Mars, 2) the climatic effects of volcanic explosions on Earth, and 3) the "possible" collision of an asteroid or comet with Earth at the time of the dinosaur extinctions. They also said they consulted a "large number of experts in atmospheric physics and chemistry" at the Cambridge meeting, and they included lots of footnotes in their article.

Sherwood Idso of the Institute for Biospheric Research rejoined in the November 29 issue:

If these reasons are indeed the basis for their confidence, the critisism they received was well justified. To begin with, what good is a technique that is only partly calibrated? And how can a model be calibrated against a possible phenomenon which may or may not have actually occurred...?

Idso pointed out that the small climate changes that result from volcanoes are caused primarily by sulphuricacid droplets, not by the kind of smoke and dust involved in the nuclear-winter models. "So how can this comparison be of any use?" he asked. He continued:

In addition, of what real comparative value is the planet Mars? It has no liquid water on its surface, while Earth is 70 per cent covered by seas; and its atmospheric mass is minuscule. Dust there operates almost as if were in a vacuum; and, again, Turco et al. claim that it is not dust but rather sooty smoke from fires that is the major cause of nuclear winter.

And as for citing lots of background material and getting the opinions of a large number of experts, what does that prove? Absolutely nothing, which is precisely the point made by John Maddox, and one which I heartily endorse.

AS THE CRITICISMS have mounted, it has become clear that there are eight vulnerable links in the winterists' argument. As Sagan had admitted in Science, if a single link in the chain of evidence is faulty, the whole argument fails. In brief, the eight weak links are:

1. Projected nuclear-attack scenarios. Most nuclear-winter war scenarios perversely target cities instead of military sites--such as nuclear-missile silos that can shoot back at an attacker. Cities are the prime sources of winter-deadly smoke. Yet it has long been Soviet policy to target American military sites, and the U.S. has been gradually shifting to military targeting since 1974.

Fire researchers at the Pacific-Sierra Research Corp. have done a minutely detailed study of the probable effects of nuclear strikes against 3,459 American and Soviet military targets. Their scenarios yielded roughly a million tons of smoke. The winterists' own minimum threshold for a nuclear winter is one hundred million tons.

2. Projected nuclear-weapons effects. Winterists admit that many or most of the fires ignited by the searing light from a nuclear explosion will be "promptly snuffed out" a few seconds later by the tremendous winds from the blast wave. They thus emphasize instead the role of "secondary fires" caused by the blast winds' "disrupting open flames, rupturing gas lines and fuel storage tanks, and causing electrical and mechanical sparks." There is, however, very little evidence of such secondary firs at Hiroshima or Nagasaki. Nuclear tests in Nevada show that gas lines and fuel tanks are extremely resistant to damage. 3. Estimated smoke and dust generation. Winterist estimates of the total amounts of smoke generated in a nuclear war have been based on almost pure guesswork. The winterists guessed at the percentage of the burnable material in the affected areas that would catch fire and came up with one-half. Their guesses about the absolute amount of fuel burned range from 0.01 to 100 pounds per square foot of city or rural area burned. For the average percentage of burned fuel that ends up as smoke, they give a range from 1 to 10 per cent. They guess, as well, at the total area that would be burned in a nuclear war. These accumulated guesses yieled anywhere from many thousands of tons of nuclear smoke up to multiple billions of tons, a range covering five or six orders of magnitude.

4. Properties of smoke and dust. Winterists use no data whatsoever on the optical and thermal properties and composition of city-fire smoke, the most important winter-dangerous substance. They use data from forest fires and even burning cigarettes, but not burning houses and offices. For the properties of nuclear dust, they use data on dust from volcanoes, which, as noted above, differs from the dust of burning cities in important ways.

5. Atmospheric transport and removal. This is another area of great controversy. Winterists' simplistic models usually begin with smoke and dust already spread uniformly around the world or in the Northern Hemisphere. "That can't happen," Rathjens declares. He and many other critics point out that clouds of smoke and dust obviously start out patchy. TTAPS admits that differential heating by sunlight at the edges of the patches will cause violent storms, which will help wash away the smoke and dust.

Smoke particles, though smaller and lighter than dust particles, are also quite "sticky" and will attach themselves to heavier dust particles, accelerating their return to earth. In fact, many dust and smoke particles will quickly turn into raindrops as moisture in the air condenses around them, or they will merge with natural raindrops, according to the analysis of University of Virginia geophysicist and air-pollution expert Fred Singer, confirmed by physicist Joyce Penner's computer simulations at the Livermore lab. The drops would then fall to the ground like the "black rain" noticed at Hiroshima and elsewhere after massive fires.

Natural atmospheric electrical charges, such as those generated in lightning, would also help remove smoke from the atmosphere. Giving smoke particles an electrical charge makes them attractive to each other, as if they were little electric magnets. Tiny clumps of charged particles will be heavier than the individual particles and will be less likely to stay airborne. TTAPS relegated the effects of atmospheric electrical charges to a footnote, and the Academy report pooh-poohed them. Neither even considered the possibility of using man-made electrical charges to clear the atmosphere. It is well known, for instance, that high-altitude nuclear radiations that penetrate the atmosphere from above, for hundreds of miles around. Thus it is at least possible that most winterizing smoke could be quickly removed from the atmosphere.

6. Climatic physics model. Anyone who reads the tabloids is familiar with climatologists' endless disputes over whether the earth is heading into a new Ice Age or is turning into a desert or a tropical hothouse. The models used to predict these possibilities--and tomorrow's weather--are the same as those used to predict nuclear winter. In either case the forecasts that result are unrealiable because the basic science behind climate models is still poorly understood. Change a few of the assumptions programmed into the computer, and you may even get a warming effect instead of a deep freeze. Virtually everyone involved with nuclear-winter studies has criticized the climatic models used.

7. Projected climatic effects of smoke and dust. As noted above, the chief objection to the winterists' projections about the climatic effects of smoke in the aftermath of a nuclear was is that none of the available empirical evidence, chiefly the events at Hiroshima and Nagasaki, confirms the nuclear-winter theory.

The question of the effects of dust is a bit more complicated because of the winterists ambivalence about volcanoes. When data on volcanic dust are used to attack the theory, the winterists argue that comparisons between eruptions and nuclear blasts are "inappropriate." Yet for certain key calculations their own models use data on volcanic dust rather than nuclear dust, and the TTAPS group proclaimed that its "nuclear-dust calculations were entirely consistent" with volcanic phenomena.

Volcanoes, however, have little climatic effect, and what effect they do have may be the reverse of that predicted by the winterists. As meteorologist Alan Robock of the University of Maryland told the Halloween nuclear-winter meeting:

We looked at the surface temperatures after Mount ST. Helens' volcanic eruption, when the atmosphere was full of dust for several days. We found that the surface temperatures did not cool but remained relatively constant. . . . the surface, completely insulated from solar radiation . . ., did not cool because it was warmed by the infra-red radiation from the dust. . . . the warm layer of dust in the atmosphere should produce a warming effect on the surface.

In other words the hot sunlit dust heated up the darkened ground, making up for the loss of direct sunlight. The Academy panel essentially conceded this point. But if hundreds of millions of tons of volcanic dust blasted high into the air produce a warming effect, why shouldn't similar amounts of nuclear dust, blasted to about the same altitudes, do the same? Indeed, Fred Singer has published numerous articles arguing that "nuclear summer" is a greater possibility than nuclear winter. Other physicists have found similar results, but their work remains quietly buried inside scientific journals.

Some winterists, when challenged, concede the warming effect but argue that it would only be temporary. But none of the important nuclear-winter models shows the warming effect at all, even temporarily. For example, the TTAPS "dust only" scenarios show temperatures dropping continuously for a total of 5 to 20 degrees Fahrenheit in the first ten days. This deliberate evasion of admitted contrary evidence goes to the heart of what is wrong with the winterists as scientists.

8. Overestimation of the greenhouse effect. Finally and most damningly, even if the nuclear-winter scenario played out exactly as TTAPS and others predict, the effects on the earth's temperature would be far less than the dramatic 70- to 120-degree drop the winterists threaten.

Nuclear winter supposedly works by canceling the "greenhouse effect," the tendency of the earth's atmosphere to transform sunlight into heat and then retain the heat. Thus the limiting cases for nuclear winter--the greatest possible temperature drops--are those that would occur when the greenhouse effect is completely eliminated and the earth becomes, as it were, an "airless planet," to use TTAPS's words. But the greenhouse effect adds, at most approximately 55 degrees to the earth's temperature. Thus (in the relevant one-dimensional models), if the earth lost all the warming effects of its atmospheric greenhouse, but lost none of its considerable reflectiveness, including that provided by shiny white clouds, the maximum temperature drop would be approximately 55 degrees. Take into account the darkening of the earth by nuclear smoke, and the drop would be approximately 35 degrees. Thus the winterists' theory is fundamentally contradictory, even absurd. For their worst-case scenario is not capable of producing the worst-case results they promote on TV talk shows and in popular magazine articles.

PROBABLY MANY of us have heard Carl Sagan describe his vision of the horrible aftermath of a nuclear war --the earth turned into a frozen, dark wasteland. He makes a persuasive case for nuclear winter.

But "persuasive" doesn't necessarily mean "true." Sagan himself says of nuclear winter that, to be taken seriously, such "apocalyptic predictions . . . require higher standards of evidence . . ." Nuclear winter fails the "higher standards of evidence" required for such Doomsday predictions. Sagan's persuasiveness is only an illusion. "Like all scientific findings," says Sagan, nuclear winter "can be shown to be true or false by objective means." But nuclear winter isn't science. It is propaganda. And the willingness of prominent men of science to debase themselves and their calling for the cheap thrills of political notoriety is a scandal.