-~ --- --~-

HARD FACTS

ABOUT NUCLEAR

WINTER BY ANDREW C. REVKIN

Everyone knew that nuclear war would

be hideous, but no one expeaed this.

Early in 1979, the Congressional Office of Technol­ogy Assessment (OTA) completed a 151-page re-­port called "The Effects of Nuclear War."The first finding, set off in boldface, was "The effects of a nuclear war that cannot be calculated are at

least as important as those for which calculations are at­tempted "That has proved to be an unusually apt caveat.

Now, only a few years after the OTA report, and four de-­cades after the invention of nuclear weapons, the scientific and defense communities have suddenly learned of an as­pect of nuclear war, overlooked by OTA and almost every­one else who had studied the subject, that could prove to be more devastating than any of the other effects--includ­ing the blast and radiation.

The forgotten factor? Smoke. Government scfendm had been studying the physical effects of nuclear aplo­sions for decades, had produced massive wlumiel ,. of detailed observations, had scrutinized &CCOUDII of lbe blasts at Hiroshima and Nagasaki, the lln!stonDs at 0... den, Hamburg and Tokyo. But no one bad calnaleled tbe! climatological effects of the globe-&paoDJDg paD of ~ smoke that could rise from tbe lbousaodl of files ........... by a nuclear war. Indeed. wltb the ezcepllon of "!0 ~ glected reports produced for tbe U.S. government In ~ 1960s, the word smoke is baldly meotloaed in lbe ldeodl-ic literature. I

A paper publlsbed In lbe Swedish Joumal~ 1982 thus came 11 a complete surprise. stunning and defeDse aped~ alike wltb Its slmpJe. ominous sion. Paul Crutzen, a Dutch atmospbertc ldentlst. uct; JolmBIIb,mAmodcaD........._~'"=~ s.n1tw,.,. Andrlw c RaJidn Is 1«11ur«1 on tlw ~ ,._

NUCLEAR WINTER

The biologists said that lthe possibility of the extinction of

have a major Impact on climate­manifested by significant surface darkening over many weeks, sub-

Homo sapiens cannot be excluded." freezing land temperatures persisting for up to several months, large pertur­bations in global circulation patterns and dramatic changes in local weath-

The shock waw loYOUid exlfngulsh some of 1he ftres set by Che lUst's thermal pulSe, but It wouJd •rso start l'l'l)'l1ad sec:oncs.ry ftres by bt'U.kfng g.s lines, fuel atnla and the Uke. GM!n 1he right amdlttons, the ftres CXKild merge Into il single lrRino.

tary but convincing way that smoke from a nuclear war­several hundred million tons of it-"would strongly restrict the penetration of sunlight to the Earth's surface and change the physical properties of the Earth's atmosphere." And theh calculations were based only on smoke from burning forests. When another research team considered smoke from burning cities, the forgotten factor took on even more significance.

Richard Turco, an atmospheric scientist at R & D Asso­ciates, in Marina del Rey, California, had been working with three researchers at the NASA Ames Research Center, two of whom were former students of Cornell astronomer Carl Sagan, on the atmospheric effects of dust raised by nu­clear explosions. When Turco read an advance copy of the Ambio study, be hnmediately saw that smoke would be far more important than dust

Turco reworked the Ambio calculations, adding in the smoke from burning cities. Along with the NASA group­O. Brian Toon, Thomas Ackerman and James Pollack­and Carl Sagan, he put together a comprehensive analysis, including computer models, of the "global consequences of multiple nuclear explosions." The group, which soon became known as TTAPS (an acronym based on last names), discovered that the smoke could have a devastat­ing effect on the Earth's climate.

The findings were so dramatic, in fact, that in late April 1983, more than 100 scientists were invited to a closed ses­sion at the American Academy of Arts and Sciences, in Cambridge, Massachusetts, to review the study. The physi­cal scientists met first, testing the assumptions, dissecting the models, checking the data. Some adjustments and re­finements were made, but the basic conclusions held.

Then the biologists took a crack at it They extrapolated from the climatic effects to the impact on agriculture and ecosystems. The destruction wrought by nuclear war, they concluded, would be much greater and more long-lived than anyone had previously conceived.

The results were announced to a capacity crowd at a conference in Washington, D.C., on Halloween 1983 and were published in the December 23 issue of Science. The TT APS group concluded that "a global nuclear war could

64 SCENCE OIGEST-MAACH 1985

er and precipitation rates-a harsh 'nuclear winter' in any season."

The biologists also presented theh findings. Their sweeping, controver­sial conclusion, later published in the same issue of Science. was that such a climatic catastrophe could "cause the extinction of a major fraction of the plant and animal species on the Earth .... In that event. the possibili~ of the extinction of Homo sapiens cannot be excluded."

The press, fresh from reporting on President Reagan's Star WatS defense initiative and the antinuclear protests in Europe. gave the news wide cover­age. The public was already sensitized to the issue by ad· vertisements for the ABC special ''The Day After," whict. was aired just three weeks later.

To be sure, not everyone agreed. A small but powerfu. cadre of critics, led by Edward Teller, a chief architect o: the hydrogen bomb and an important force at Lawrence Uvermore National Laboratory, attacked the reports, argt!­ing that the studies were inconclusive and politically motl­vated. "The only news," Teller says, "is that Sagan has made a lot of propaganda about a very doubtful effect''

T hree congressional hearings, dozens of scientific meetings, several international conferences anG at least four books later, nuclear winter has tak· en its place-somewhere between megaton ana ouerki/1-in the burgeoning lexicon of terms

spawned by the study of nuclear war. After more than a year of scrutiny, the TTAPS study bas held up, at least as a "first order" estimate. "Critics of the original paper proba­bly never read it," says Startey Thompson, an aunospheri.;; scientist at the National Center for Atmospheric Research (NCAR), i.n Boulder, Colorado, who bas contributed to se-:­eral subsequent computer analyses of the concept "If th~. had read it carefully they would realize it's not very O\'er­stated. It has lots of caveats in it What has probably been overstated has been public discussion. When you put It a.. together, it looks bad."

Almost everyone agrees on one point the need fo~ more research. " It's been an instant field," says Bob Cess a specialist in clhnate modeling at the State University o:: New York, Stony Brook, who is working on the problerr. with researchers at Lawrence Uvermore. "Never has sc much been said about a field in which so little has be-er. done."

The only absolute quantity in the entire concept is the fantastic power of the bomb. The uncertainties are mul:i­fold and frustratingly complex. Many aspects of the micro­physics of lire and smoke and the macropbysics of weat."l­er and climate are still mysteries. in fact, S. Fred Singer c. geophysicist at George Mason University in Fairfax, Virgm­ia, and a consistent critic of the TTAPS work, has argued .~ both Nature and the Wall Street Journal that, given lt.e right conditions, a nuclear war could produce a dark. h :1t

···nuclear summer." Moreover, the computer-generated models being used to study nuclear winter are---<lespite the advent of supercomputers and weather satellites--still patchwork attempts to simulate the global climate.

The formula for nuclear winter is rife with variables as well as uncertainties. What type of nuclear war might be fought? How many warheads, of what megatonnage, would be exploded? (One megaton is the explosive power of one million tons of TNT -an amount of explosives that would fill a freight train 300 miles long.) Are the targets "bard" or "soft," silos or cities? Does the war last a day, a week, months? Does it take place in summer, in the middle of the growing season, or in the chill of winter, when a drop in temperature might do less damage?

Yet another sticking point has been finding reasonable numbers to substitute for these variables. Most of them are secrets, embedded in the closely guarded targeting scenar­ios and combat strategies of the United States and the Sovi­et Union.

In December, the National Research Council published an exhaustive review of "the effects on the atmosphere of a major nuclear exchange." Their best estimate was that there is a "clear possibility'' that nuclear war would lead to nuclear winter. Their main conclusion was a call for more research. Soon after, Alan Hecht. director of the National Climate Program Office of the National Oceanic and Atmo­spheric Administration, submitted a plan for a five-year program of research on nuclear winter to President Rea­gan's science adviser. The program will focus on climate models and the physics of smoke.

While government has slowly been getting into gear, scientists at institutions as disparate as Lawrence Uver­more, which is one of the nation's leading weapons laboratories, and universities such as Cornell and Colo­rado State are devoting spare hours and odd scraps of funding and com­puter time to nuclear-winter studies. Some are refining mathematical mod­els of fires and climate that are testing the limits of supercomputer technolo­gy. Others are looking to the past, even to other planets, to try to find events, such as volcanic eruptions, dust storms and meteor impacts, that might provide useful analogies to some of the effects of nuclear war. And biologists, who have been largely left out of the federal plan, are hoping to increase general understanding of the ecological consequences of nucle­ar winter.

The stakes are high- as high as can be. If the probable outcome of a nuclear war is a nuclear winter, non­combatant nations can no longer con­sider themselves outside the fray. As for the members of the nuclear frater­nity, particularly the United States and the Soviet Union, the implications for military strategy, civil defense and arms control are vasl

its bottle since it was unleashed on Japan 40 years ago. If nuclear winter is proved plausible, MAD may be replaced by a simpler form of deterrence, assured self-destruction, which guarantees that a nation launching a nuclear attack will in effect be committing suicide.

According to Sagan and many others, nuclear winter is thus an unexpected panacea. delivered in the nick of time, that may make nuclear weapons "obsolete" by turning them against their users. But others, including Freeman Dyson, a physicist at the Institute for Advanced Study, in Princeton, and the author of Weapons and Hope, predict that if the theory is confirmed, it could create a new, dan­gerous arms race-a race among military planners to make nuclear war "safe" again.

S pelled out, the theory of nuclear winter is as sim­ple as the chill you feel when a cloud passes in front of the sun, and it is as complex as the ever­changing patterns of wind and weather that swirl daily across the surface of the globe.

It is based on phenomena as minute as the behavior of the individual particles within a cloud of smoke and on events as massive as the explosion of a thermonuclear warhead with the force of 2 billion pounds of TNT.

In general, the theory holds that the sun-hot fireballs of thousands of exploding warheads would set forests, fields and, especially important, cities ablaze, lofting plumes of dark smoke near the boundary between the troposphere­the lowest region of the atmosphere, where weather oc­curs-and the stratosphere, the static, weatherless region that starts six to eight miles up.

Cities are important because they are loaded with

..

The long-standing balance of ter­ror, called mutual assured destruction (MAD), has kept the nuclear genie in

1he bombing of the German city of Dresden In 1945 produced one of the ftrst, and most destructtve, marHNide ftrestonns In h.::?.'. Almost 1KfY flllrrm111ble material within an elghMqullre-mlle area was Jndne . Winds of nuf'ftmtcane fonle toppled trees and fanned the flllmes. Jt Is estimated that at leat 35,000 people perished.

65

NUCLEAR \MNTER

The smoke cloud, and thus the cold and dark, could spread across sensitive tropical ecosystems.

Earth radiates this energy back toward space in a different form, as infrared radiation (IR).

Fortunately for humans and other life forms, not all of the radiation es­capes into space. If it did, the Earth would have a surface temperature be­low zero Fahrenheit. The heat is

fuel-plastics and petroleum, wood and paper. Reservoirs of oll and gasoline, dense downtowns and sprawling neighborhoods of wood-frame houses and tenements give cities their high fuel density. Moreover, petroleum and plastics produce more, and darker, smoke than wood ln fact, Art Broyles, a physicist and fire expert at the Universi­ty of Aorida, estimates that even though these materials make up only about 5 percent of the fuel in cities, they would probably produce as much smoke as the rest of the fuel, which is primarily wood.

The individual clouds of smoke would coalesce after a week or two. Pushed by strong west-to-east winds, the smoke would form a uniform belt of particles girdling the Northern Hemisphere from 30 to 60 degrees latitude, a re­gion that reaches from central Aorida to southern Alaska. The weapons' blasts would also raise tons of dust into tbe stratosphere, where it can remain for years.

T be smoke, and to a much smaller extent the dust, would prevent all but a tiny fraction of sunlight from reaching the surface of the Earth in the Northern Hemisphere for weeks, possibly months. According to the TIAPS study, after a

"baseline," or medium·size, nuclear war, in which war­heads with a total yield of 5,000 megatons were exploded over a variety of targets, average surface temperatures would drop 60 degrees Fahrenheit-below freezing even in summer-destroying agriculture, disrupting ecosystems and making the postwar world a nightmarish mix of cold, dark and starvation for those humans who survived the other effects. The study also projects the possibility that the high-altitude smoke cloud, and thus the cold and dark, could spread across the equator, plunging sensitive tropi­cal ecosystems and the naUons of the Southern Hemi­sphere into chilly twilight

By blocking sunlight, the smoke would disrupt the transfer of radiation from the sun that creates and main­tains Earth's equable climate. Most of the sun's energy is transmitted as visible light Sunlight penetrates the atmo­sphere and sbikes the continents and the oceans, which, t.o varying extents, absorb the energy and heat up. The

66 SCJENCE DIGEST-MAACH 1985

trapped by the so-called greenhouse effect As TIAPS explains, "The atmo­sphere generally ads as a window for sunlight but a blanket for heat" Car­bon dioxide, water vapor and the wa. ter in clouds all absorb some of the es­caping energy. The air nearest the surface absorbs the most heat. giving Earth its 56-degree-Fahrenheit aver­age surface temperature. But the air cools rapidly with increasing altitude, to about -67 degrees at the upper Urn­

it of the troposphere. The entire troposphere is stirred up and set into motion when the low, heated air masses rise-a process called convection. This is the main source of weather: clouds, wind and precipitation.

Smoke has optical properties that make it a better blocker of sunlight than dust or water clouds. VISible light is transmitted at wavelengths of between 0.4 and 0.7 mi­crons (a micron is a millionth of a meter). A significant fraction of the particles in smoke are less than a mlaon in diameter. Dark particles of this size are ideally suited to ab­sorbing energy at those wavelengths.

The result? If enough cities are bumed-and according to one of the TIAPS scenarios, 100 dties will suffice-the atmosphere will be turned on its head. Sunlight will be ab­sorbed not at the surface but by the layer of smoke in the upper troposphere. The smoke and the troposphere will heat up, and the Earth below, deprived of up to 95 percent of its daily ration of solar energy, will cool.

The TTAPS group calls this the "anti-greenhouse ef. feet" One consequence of such a mass inversion would be a lack of convection. With few rising pockets of heated air, there would be little atmospheric turbulence, fewer storms and thus less of the natural "scavenging" process- ~ es, including rain, that normally remove particles from the i air. To make matters worse, as the smoke-laden air in the I upper troposphere grew warmer, it would tend to rise even i higher, taking it farther from the region of cleansing predp- 5 itation, perhaps as high as the stagnant stratosphere. The ~ nuclear-winter effect, in Sagan's opinion, could thus be I self-perpetuating. s

The TTAPS researchers are the first to point out that ~ their effort involved many assumptions. The model they i used to chart the temperature prome of the atmosphere was one-dimensional, representing the averaged global at- l mosphere as a single column of air. The smoke for each of ~ several dozen different war scenarios was assumed to be ~ spread uniformly and irlStantaneously over the Earth. Rath- ~ er than taking into account the oceans, which act dramati- ~ caUy to buffer any sudden climatic changes. separate com- , puter runs had to be done for an all-water planet and an ~ all-land planet {with 70 percent o1 Earth's surface being ~ water, that is a large simplification). The simulations em- • ployed a feature common to such models-a fixed sun- § that leaves out any possible effect of the daily cycle of light . ~ anddark. 3

Despite these and other assump­tions, subsequent two- and three-di­mensional computer analyses have, for the most part. only mitigated the effects described by TTAPS. Coastal regions and islands would escape the brunt of the deep freeze but might be subjected to extraordinary storms as the warmer air over the ocean clashed with the cold air over land. Clear patches in the canopy of smoke, low­lying fogs and other factors would lessen the effects. But only in a few cases have simulations failed to show significant, potentially destructive cooling of the Earth's surface.

Mark Harwell, a Cornell biologist who recently finished a book on the subject, says, "You don't have to go to the extreme bounds of any of these ranges of uncertainties to be able to generate a nuclear winter. Actually, the converse is true. To come up with a war that does not generate a nuclear winter, you have to go to the ex­tremes." Commenting on the critics of TTAPS, he adds, "You can talk your­self into saying, 'Gee, I could have a nuclear war that didn't lead to nuclear winter,' but it takes a lot of soft-shoe routine. I've seen people do it"

Here are some of the other findings that have appeared recently:

The atomk bomb thlrt the United Stlltes dropped on Hiroshima In 1945 tNid • yield of 16 kilotons, less than one pera!f1t of the powter of some of the smallest modem nudar WNponS. The resu~ flrestonn destro)<ed the city and raJsed a thld<, dartc pall of smoke. Witnesses thlrt the air grew cool and a ''black rain" feU.

• Michael MacCracken, at Lawrence Livennore, ran a three-dimensional global-circulation model (GCM) that showed a 25-to-30-degree-Fahrenheit drop in average sur­face temperature beneath the smoke cloud-half the TT APS finding, but still catastrophic by any estimation.

• Vladimir Alexandrov, head of the climate research laboratory of the USSR Academy of Sciences, using a dif­ferent GCM and a 1 0,000-megaton war scenario, reported a temperature decrease similar to MacCracken's. ·

• Starley Thompson, Curt Covey and Stephen Schneider, at NCAR, running one of the most sophisticated climate models available, got results that support some of the TT APS work, and they also observed a remarkable fea­ture they called a quick freeze. The model produced patch­es of freezing temperatures that migrated at random across the globe as early as two days after a nuclear war. (TTAPS predicted the onset of freezing conditions after two or three weeks.)

MacCracken says the NCAR fmding Oags a major weak­ness in almost all the studies that have been done so far. ''What we should be looking at is not the change in cli­mate-the average conditions-but the change In weath­er, which is sho~-term, day-to-day fluctuations." A quick frost at the wrong time is all that is needed to destroy a year's cops.

According to Schneider, the quick-freeze effect also shows that input from the biologists is extremely important to nuclear-winter studies. "You don't know what to gener­ate from a physical model unless you're guided by what matters to the biosphere." he says. "We might not have looked for [quick frosts) if one of the biologists hadn't sug­gested it''

A 11 of these global-scale models have major flaws, not the least of which is that they were originally designed to study problems that are tundamentaDy difierent from nuclear winter. According to Bob Cess, at Stony Brook, many

of the models were created to analyze the gradual, almost imperceptible buildup of carbon dioxide in the atmo­sphere that may someday cause a runaway greenhouse ef. feet "Now we're using them for a vastly different thing," he says. "We're going to have to start understanding how the models respond to a vezy large forcing-when you really hit the climate over the bead with a sledgehammer Instead of just barely tweaking it"

The models are also limited by the reliability of the data that go into them. "U you have garbage in, then you've got garbage out," Cess says. ''You start cascading the question marks one on top of the other."

Richard Turco, the first Tin TT APS, says the best we will end up with is "a probabilistic picture of what could hap­pen." Starley Thompson agrees: "If you knew every­thing-what the initial meteorological conditions were the moment the war started, where the bombs were going to hit-in theory it's possible to have a model that would pre­did all the details of a nuclear winter. But all those things are essentially unknowable."

At this point, most of the climate-modeling researchers say one thing is dear. If enough smoke gets high enough, and stays there long enough, there will be significant sur­face cooling. But that is a big il Several questions remain, and they all concern smoke. How much is produced? How high does it go? How long does it stay airborne?

Conffnued

67

HARD FACTS The amount of smoke produced de­

pends first on the nature of the war. The range of possibilities Is Impressive-any number of combinations of "counter· fOJCe" strikes. against military ~ts. and "countervalue" strikes, against industrial assets. The only limit is the total number of weapons available. Wlth the combined nuclear arsenals of the United States and the Soviet Union containing 50,000 strate­gic and tactical weapons that is not much of a limit

"CUes Will Be Struck"

More specifically, smoke production de­pends on how many dlies bum. OfticiaiJy, they are not targeted, but most defense ex· perts assume that It would be impossible to light a nuclear war without hitting cities. Admiral Noel Gayler, now retired, has been Commander U.S. Forces Pacific, dJ. rector of the National Security Agency and deputy director of the Joint Strategic Tar· get Planning Staff. In testimony last year before the Joint Economic Committee of Congress. he said. "Whatever the declara­tive policy of either country, the weapons that go after leadership, controL mllitary capabiUty, industrial capability or eco­nomic recovery will hit cities. ... We must face up to lt. Whatever our rhetoric or theirs, in a general nuclear war cities will be struck, and they will bum."

The amount of smoke depends not only on how many cities burn but on how well they bum. That dties can burn excep. tlooally well was amply demonstrated in World War II. The Allies raised bumlng them to a science with a series of devastat· ing raids on German industry and popuJa. tlon centers late in the war.

Early on the mornlng of February 14, 1945, the British Air Ministry announced that the German city of Dresden had been attacked. Hundreds of 4,()()0. and 8,000-pound bombs and more than 650,000 In­cendiary devices were dropped in the first wave of the assault The result was a fire­storm-a fire so fierce and hot that its up. drafts sucked in air from all sides at near­hurricane force. Uke a beUows blowing on a blacksmith's forge, the winds nourished the Dames with fresh gusts of air, raising temperatures thousands of degrees.

A British bomber pilot, one of the last to fly over the dty that night. later recalled: "Th.ere was a sea of lire. ... The heat strik· ing up from the furnace below could be felt in my cockpit ... The light inside the aircraft was that of an eerie autumn sun· set We were so aghast at the awesome blaze that although alone over the dty, we flew around Ln a stand-off posiUon for many minutes before turning for home. •.• We could still see the glare of the holocaust thirty minutes after leaving."

Several researchers are studying urban fires, but this is an area with Uttle hard data. Sang-Wook Kang. a staff scientist at Lawrence Uvermore, says it isn't even 68 SCIENCE DIGEST-MARCH 1«;85

clear what conditions lead to a firestorm as opposed to a conflagration, which is a large but unfocused blaze.

Kang, Michael Mac<:racken and others doubt that proposed studies of experlmen· tally set fires and accidental fires will bear much fruit. "The real problem," Mac· Cracken says. "is trying to scale lrom a reJ. atively small fire-even a city block, for example-to what might happen If you have a megaton explosion that sets nine­ty-five square mUes or so on fire at the same time. No one bas any idea how to do that"

Once more, supercomputers come into play. Kang is piecing together a three­dimensional computer model of ul'ban· fire behavior that he says is even more complex than many of the atmospheric models. It will focus on the buUding-to­bulldlng spread of the names, a process that depends on things as subtle as the fate of win<kirlven firebrands-even the layout of furnishings within buLidings. "Given the same two-story wooden struc­tures," he says, "If the fumlture Is placed at different ends. the fire history is going to be different" He foresees five years of ba-

''I'm sure a buming New York City would produce a different kind of smoke than

a buming Moscow."

sic research. The length of time the smoke stays m

the atmosphere depends In part on the chemistry of the individual smoke part.i· des. The nature of the particles affects the scavenging rate: Can they provide nuclei upon which water will condense? II so, rainfall following a nuclear war could rap­idly clear the air. Do the particles stick to­gether when they coUide? Th.is process, called coagulation, makes them fall to Earth faster. And, according to Bob Cess, there is another factor to consider: "I grew up In western Oregon," he says, "where we saw lots of forest·fire smoke in the summertime; It's very light stuff that looks just like water clouds. But a refinery fire is a totally different thing. And I'm sure a bumlng New York City would produce a different kind of smoke than a burning Moscow. So there's no single smoke char· acterlzatlon that's going to work in this business." The proposed federal research program includes laboratory Investiga­tions of these questions.

How high will the plumes of smoke rise? According to a computer simulation developed at Colorado State University, the smoke may go even higher than TTAPS predicted. Wllllam Cotton, an at·

mospheric scientist, burned Denver. Fortunately for that mUe-high city, Cot·

ton did it on a Cray I supercomputer. He used a three-dimensional model that Colo­rado State researchers had designed to study the behavior of powerful thunder· storms. As far as the atmosphere is con­cerned. be says. a nuclear explosion and the resulting fires aeate a "convective dis­turbance" that is not that different lrom a thunderstorm; they produce an immense column of rising hot air. Cotton discov· ered that almost balf of the smoke general· ed by the computerized flrestorm was driven Into the stratosphere--where It could reside for years instead of months.

The model is a mathematical grid, 28.5 mlles square and divided vertically into 32 slices, each 0.45 of a rnlle thick. It took eight years to design, says its creator, Greg Tripoli, and Includes more than 50,000 commands. Numbers are assigned to each grid point that represent the normal atmosphere; in this case, Cotton filled In the blanks with data that reflected the me­teorological condJtions over Denver on a particular day, June 4, 1983: Wind, tern· perature and humidity were entered for each grid point at each altitude.

Then the bomb was dropped; the re­sulting firestorm was represented In the model by a huge flux of heat emanating from a circular region five mlles aaoss. The temperatures were determined by es­timating how much fuel-wood, petro­leum and the Uke--was available over how large an area. Smoke production was similarly estimated. The program respond­ed to these "pertUrbations" and began to churn out numbers. This Is what they add. ed up to:

Vast gusts of hot air, rising 260 feet per second, burst through the cool atmo­sphere. Wate.t vapor in the updrafts con­densed, creating a thunderstorm. The fire­storm and the newly spawned thunder· storm combined forces to lift 1,400 tons of smoke into the upper atmosphere. Almost half of that made it into the stagnant, weatheriess stratosphere.

Compllalted Slmulattons

The hypothetical blaze lasted less than an hour, but it took 10 hours of time o.n the supercomputer-an indlcatlon of the complexity of the simulation. "It actually brought the Cray computer down to Lts knees a couple of times during the simula­tion because so much data was flowing in and out." says Cotton. "We're right up at the top end of the technology we bave available."

Cotton is careful to say that the results are preliminazy. The day he chose, June 4, was especially conducive to thunderstorm formation. and Denver is hardJy a typical dty because of Its high altitude.

Since then, Bob Banta. a former col· league of Cotton's, has repeated the simu· latlon, using average weather condl· tion&-<:alled a standard sounding-for a city at sea level. Banta, now a physical sd-

Contfnu«< on PQ8t! 77

BUY ONE, ENJOY THREE

HARD FACTS Continued from page 68

enlist at Hanscom Air Force Base in Mas­sachusetts, says he got 22 percent of the smoke into the stratosphere-half as much as Cotton but still more than TIAPS. The smoke is lofted so high so quickly, Banta says, that the scavenging processes that normally remove particles from the atmosphere don't have time to work.

This work has been hailed as extreme­ly important by many in the nuclear-winter research community. Even so, Cotton's paper was rejected last fall by Science.

·There is one more question, perhaps the biggest one of all, that concerns smoke: How could the significance of smoke, the cornerstone of such an enor­mous, il putative, environmental cata­clysm, stay hidden for so long? At a con­gressional hearing last summer, Richard Wagner, Jr., Assistant to the Secretary of Defense (Atomic Energy), testified, "Not only the Department of Defense but the scientific community in general ought to be a bit chagrined at not realizing that smoke could produce these effects."

John Birks, one of the authors of the Ambio study. offers two answers: "De· tense scientists, who are the ones funded to look at this, are not attuned to this sort of thing. Their job is to build weapons to prevent war. Their work has focused on prompt effects of single nuclear explo-

sions. They have had no incentive to look at global effects of multiple nuclear explo­sions." As for why university researchers didn't catch on to the importance of smoke, he says, "You don't get brownie points in academia for studying some· thing as applied as nuclear war. You don't get promotion and tenure and things like that So there's no incentive there either."

HFull of Sloppy Work"

"It's very strange," says Richard Turco. "When you look back through the litera­ture, which mainly consists of the 'gray' lit· erature-reports and things of that sort­you can literally pick up a handful of re­ports that have addressed these possible long-term consequences of using nuclear weapons in large numbers. And those are not very authoritative, are fuJI of very slop­py work and aren't very imaginative. And you have to wonder why that is. I think one reason is everybody always assumed that It's going to be such a disaster an-jway that 'who cares?' "

In 1962, Robert Ayres, then at the Hud­son Institute, undertook a three-year study of the environmental effects of nuclear war for the Office of Civil Defense (now absorbed by the Federal Emergency Man­agement Agency, FEMA). He realized that smoke could have an effect on climate. But because he was working alone, "with no computers or fancy mathematical models," he did not try to calculate specif­ic consequences.

Ayres, who is now at Carnegie-Mellon University, says a nuclear war will proba­bly have some adverse climatic impact, but still thinks it unlikely that this ''would dominate over blast and radiation." Wl)en he reviewed the TTAPS report. he says, he found only two paragraphs on what he considers to be the biggest question: the possibility that most of the smoke wlll be scavenged by rain before it has a chance to affect climate. "Frankly," Ayres says. ''I was somewhat dismayed that they jumped to such dramatic conclusions."

In 1966, Edmund Batten, working for the Rand Corporation, produced a report titled "The Effects of Nuclear War on the Weather and Climate" for the Atomic En­ergy Commission. He mentioned smoke, but only smoke from forest fires. As an ex­ample, he referred to a massive fire that burned 3,800 square miles in western Can­ada. Among-its effects, "the pall of smoke from the 1950 Alberta fire was believed re­sponsible for reducing the incoming [so­lar] radiation by fifty-four percent and low­ering the temperature ten degrees Fahrenheit at Washington, D.C."

Despite that startling finding, he con· eluded that "these short-term effects are not expected to last for more than a few weeks."

Starley Thompson recently came across the Batten study. "Now that I find out that people actually thought about smoke as long as eighteen years ago," he

Continued on page 81 77

HARD FACTS Continued from page 77

says, " it surprises me more and more that somebody didn't draw the connection more strongly. Batten himself tended to ig­nore it in favor of dust If somebody with radiative transfer experience had read that paragraph, they would have probably hit upon (nudear winter] eighteen years ago."

The Office of Civil Defense funded yet another study in the 1960s that seemed to miss the mark. "Project flambeau, an In­vestigation of Mass Fire," was a three-year effort to simulate intensive urban fires and study their behavior. According to a report by Clive Countryman, the project's first di· rector, mock city blocks were constructed by laying out grids of up to 324 "houses," each a square stack of 20 tons of pinyon pine and juniper, 46 feet on a side and about 7 feet tall. Instruments of every de­scription were strung around, above and within the firebed. The flres were set with simultaneously ignited pouches of jellied diesel fuel Smoke partides were trapped, temperatures (up to 3,000 degrees Fabr· enbeit in some cases) were measured, winds were docked. Thousands of pages of data and thousands of feet of film were collected-and almost nothing was done with it

Funding for Research CUt

Around 1970, most of the funding for the Office of Civil Defense was cut, and that was just about the only agency requesting this type of research.

For more than a decade, nothing hap­pened. And, according to John Birks, when he and Paul Crutzen finally realized that smoke could obscure the sun. It oc· curred to them purely by chance.

Buts. a chemistry professor at the Uni­versity of Colorado, went on sabbatical in 1981 to study computer modeling with Paul Crutzen, a director of the Max Planck Institute for Chemistry in West Germany. Around that time, Crutzen received an in­vitation to contribute a section on the at· mosphere to a special issue of Ambio, which is published by the Royal Swedish Academy of Sciences, on the human and ecological consequences of nudear war. Because Birks had previously worked on the effects of nudear explosions on the ozone layer, the two scientists decided to collaborate. Since 1975, it had been as­sumed that the major atmospheric pertur· bation produced by nudear war would be severe depletion of the layer of ozone high in the stratosphere that prevents harmful quantities of ultraviolet radiation from reaching the Earth.

Crutzen and Birks chose the ozone problem as a natural starting point But. says Birks, things had changed since 1975. Warbeads had become smaller as accura­cy improved. Warheads of less than half a megaton are not powerful enough to in· ject nitrogen oxides, compounds created in the thermonudear fireballs, into the

stratosphere where they can destroy ozone.

So the two scientists turned their atten­tion to the troposphere, the lowest six miles or so of the atmosphere, to see what effect the nitrogen oxides would have there. One ingredien~ in a postwar atmo­sphere would be smoke. In the presence of sunlight, the nitrogen oxides would re­act with compounds in the smoke, a pro­cess that produces ozone-just the oppo­site of what would happen in the stratosphere. Ozone at the Earth's surface is toxic to many plants and a major com­ponent of smog.

But, recalls Birks, they reasoned that the same smoke that would contribute to smog formation might also cut back on the amount of sunlight, and that could lim­it the production ol noxious ozone. They still didn't realize what they were working toward, but they were getting dose.

To measure the reduction in sunlight, Crut.zen and Birks needed to estimate smoke production and did so using data gleaned from studies of forest fires. It ap­peared that several hundred mUllon tons of smoke could be lofted into the atmo­sphere. "We found out that easily some­thing like ninety-nine percent of the sun­light could be blocked," says Birks.

Suddenly, ozone became a side issue. With less than three months to go before their deadline for the artide, Crutzen and Birks completely changed focus. The title they chose reflected the new findings: "The Atmosphere After a Nuclear War: Twilight at Noon."

The TIAPS group was uniquely quali­fied to take over where Crutzen and Birks left oH. Their experience with the effects of aerosols-particles suspended In the air-went all the way back to 1971. Carl Sagan was involved with the Mariner 9 mission to Mars. The probe arrived at Mars to find the planet engulfed in a global dust storm--a common occurrence, ac­cording to Sagan-that lasted three months. While the scientists back on Earth were waiting for the storm to dear, they had the probe take temperature readings of the atmosphere and the surface. They noted that the atmosphere got warmer, ap­parently because the suspended dust ab­sorbed the sun's energy, while the surface grew cooler. Once the dust settled, condi­tions reverted to the norm-warmer sur­face and cooler, dear atmosphere.

Comparing Mars and Earth

In 1976, Sagan, Brian Toon and James Pol­lack published a paper in which they com­pared the Martian observations with events on Earth, specifically climate changes following volcanic eruptions.

A well-documented example was the 1815 eruption of Tambora in what is now the Indonesian archipelago. The year that followed that catadysm, which blew off the top 4,000 feet of the conical mountain, was later referred to in New England and Europe as "Eighteen-Hundred-and-Froze-

Continued on page 83

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to-Death" and "the year without a sum· mer." Crops failed across both conti· nents--and that was the result of a drop in average tempe.rature of only 1.8 degrees Fahrenheit

In 1980, another catastrophic event, the extinction of the dinosaurs, had been tentative.ly linked to a wayward asteroid that may have collided with Earth 65 mil· lion years ago, blasting vast quantities of fine dust into the atmosphere. Toon and Pollack joined forces with Richard Turco and calculated that the collision might have created a period of prolonged cold and darkness. The seeds for TTAPS were sown. All that was needed was the nuclear connection and the link to smoke. The for­mer was provided when Turco and Toon were asked by the National Academy of Sciences to contribute to a massive study on the effects of nuclear war. The latter, of course, was provided by Crutzen and Birks. Finally, Turco, Toon and Pollack were joined by Sagan and Thomas Acker· man, a computer expert at the NASA Ames Research Center, and TT APS was born. Says Turco, "We just sort of synthe­sized information from a large number of areas and combined that with understand· ing how the climate works. The informa­tion was sitting there; it just needed to be gathered and tied into a package."

The Fate of the Theory

The fate of the nuclear-winter theory will not be decided in anything approaching a definitive way for at least three years, ac­cording to most of the researchers que­ried. Even then, there will only be a reduc­tion of probability, a closing in on a plausible course of events-nothing com­pletely definitive.

In spite of the potentially enormous ramifications of nuclear winter, there are those who doubt it will affect public poli­cy. Robert Ayres, at Carnegie-Mellon, says that Sagan may have damaged his scientif­ic credibility by discussing the political im· plications before the validity of the theory is confirmed. In his contribution to TT APS critic Fred Singer's forthcoming book about nuclear winter, Ayres says, "The transparency of Sagan's motives may have detracted from the effectiveness of his argument .. . The nuclear hard-liners in the Reagan Administration will be ultra· suspicious of any conclusions based on mathematical models that are not com· pletely and fully tested and verified. They will point out, correctly, that it would be doubly disastrous if the U.S. leadership be­lieved in the Sagan thesis while the Soviet leadership did not."

He is echoed by Edward Teller, who has been playing devil's advocate to the TTAPS group for more than a year. "My main worry is that [nuclear winter] may be exploited as a propaganda point by the So­viets," Teller says. "They tell their people

what they like, whereas we tell our people what Sagan likes."

Despite his public denunciations of the TTAPS group, Teller has conceded in con­gressional testimony that a nuclear war could have significant climatic effects. He has also proposed contingency measures that he says would lessen the impact For example, Teller says, "we should increase our food storage, which is for us very easy and for others possible." He has even ten­tatively discussed the idea of firing rockets into the atmosphere filled with micron· size needles that "resonate with the infra. red, but which let visible light through," thus countering the nuclear-winter effect by keeping in the escaping heat

A Kind of Weather Lottery

Richard Turco has labeled these respons­es "absurd." He describes a similar mind­set he has seen among other members of the defense community: ··one guy said, 'Well, if it gets ten degrees colder we'll just grow the com in Mississippi, move the com belt down.' Well, that's fine if you just had these nice temperature contours and you could figure out where exactly the eli· malic situation is going to be good for com. But that's not the way it's going to work. It's kind of a weather lotterv or rou· Jette that you can never resolve. Also, no­body's ever used these weapons, so we really can't predict what's going to happen anyway."

Freeman Dyson says nuclear winter is a positive thing, "because it is a powerful political force against nuclear weapons. It is dramatic and beautiful." But Dyson sees a darker side to this nascent theory. " It is somewhat analogous to what Unus Pau­ling did in the 1950s when he fought against nuclear weapons on the fallout is­sue," be says. The public became educat· ed to the dangers, but "unfortunately, the atmospheric test ban treaty carne along and got rid of the fallout without getting rid of the testing." Dyson says the danger now is that the military response to nuclear winter, if research tends to support it, may be to "get around it in a technical fashion . ... Change targeting doctrine and de­ployment, produce only warheads of less than a hundred kilotons and the thing goes away-just like fallout"

Uncertainty Is Desirable

But Dyson, Schneider, Sagan and others still say the final effect will be positive: The very uncertainty that plagues research intt~ the phenomenon is desirable. Schneider says, "A lot of the young guys who work with me ask, 'Is there any chance that l could make war more probable by these studies?' And the answer is there's always a chance. But the only way you make war more probable is by giving one :;ide the belief it has a distinCt advantage it didn't used to have."

According to Dyson, "the ideal an­swer" to the nuclear-winter question will be, ·• 'Yes, this may happen, and there's no way we can ever tell.'" •

It life jutt a haphazard phe­nomenon? Are there but blind mechanistic laws, causes and ef­fects without purpose? Is there a reason for our personal existence? Can we establish a personal mis­sion that will be in harmony with Infinite Reality-or must we drift along, buffeted by the winds of chance? These are subjects fasci­natingly explored by The Rosicru­cians, a worldwide fraternity. Ask for a free copy of the book. The Mattery of Life.

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