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The Medical Implications of Nuclear War, Institute of
Medicine. @) 1986 by the National Academy of Sciences.
National Academy Press, Washington, D.C.
LONG-TERM CONSEQUENCES OF AND PROSPECTS
FOR RECOVERY FROM NUCLEAR WAR: TWO VIEWS
view ~
CARL SAGAN, PH.D.
Cornell University, Ithaca, New York
I have tried to read all the papers presented in this remarkable volume
and have been impressed with the diversity of topics covered: targeting
and prompt effects of nuclear explosions, atmospheric physics and chem-
istry, biological consequences, and the wide range of medical effects,
which is the central orientation of the book. I believe that this is the first
interdisciplinary examination of the consequences of nuclear war that gives
significant attention to the psychological and psychiatric aspects, which
surely are a major part of the problem both pre- and postwar.
It is striking to see how many new results have been announced on
subjects that everyone thought were well-understood. The immediate and
especially the long-term consequences of nuclear war seem to hold an
enormous number of surprises, almost all of which are unpleasant. It is
as if we live in a field of stones that no one has ever looked under. When
finally we succumb to our curiosity and turn the stones over, we find a
nest of vipers under many of them.
There is a kind of deadly embrace between the United States and the
Soviet Union their military establishments depend on each other that
goes back at least to 1945 and that has led to the construction of a kind
of global doomsday machine, which has been almost entirely ignored until
lately. The population of the planet has, by and large, been sleepwalking
through the last 40 years. The consequences of nuclear war, even as they
were known 20 or 30 years ago, did not permeate the public consciousness.
And that is still the case, although less so, as a kind of race transpires
between how fast new and disquieting discoveries are made about the
555
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556 LONG-TERM CONSEQUENCES ID PROSPECTS FOR RECOVERY
nature of nuclear war and how fast these discoveries are absorbed, often
with great reluctance, into the consciousness of the public and the gov-
ernment.
In this summary I proceed in rough serial order through some of the
topics presented in this volume and give a few impressions. On the nuclear
winter issue itself, there now seems to be a fairly broad consensus after
the original TRAPS study that it is something worth worrying about,
something probably very grave. Even the most conservative and carefully
phrased reports on this subject make that apparent. The National Research
Council's reports states that nuclear winter is a "clear possibility" and
that the probability that the severity of nuclear winter would be worse
than in the "baseline case" is roughly the same as the probability that it
would be better. Despite uncertainties, "the committee believes that long-
term climatic effects with severe implications for the biosphere could
occur. "
Much stronger statements were made in early 1985 in a report by the
Royal Society of Canada3 (it called nuclear winter a "formidable threat"),
in various Soviet publications,4 and in September 1985 in the SCOPE/
ENUWAR (Scientific Committee on Problems of the Environment/En-
vironmental Effects of Nuclear War) report by the International Council
of Scientific Unions,5 a real tour de force involving hundreds of scientists
from some 20 or so nations over a period of 3 years. They conclude that
"the risks of unprecedented [climatic] consequences are great for non-
combatant and combatant countries alike." I recommend that everyone
take a close look at the first volume on the physical effects of nuclear
war. It is an excellent summary of what we currently know. And the
second volume on the biological effects in many places plows important
new ground, which is especially useful because there is a curious reluct-
ance on the part of the U.S. government to fund work on the biological
consequences of nuclear winter. I will return to this question.
The issue of the reliability of nuclear winter must of course be raised.
The subject is not readily amenable to direct experimental verification-
at least not more than once, and very few people wish to perform the
experiment, as important as it is to know the answer. The issue of reliability
has been described6 as analogous to what in the United States, perhaps
unfortunately, is called Russian roulette. You have a revolver that has six
chambers. It is filled with an unknown number of cartridges, but probably
more than zero. The chambers are spun; you put the revolver to your
temple and are about to pull the trigger. How relevant is it that you have
some doubt about how many of the chambers are filled? Would you do
something very different if only one chamber were filled or if five or six
were filled?
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557
Perhaps the greatest uncertainty at present has to do with the duration
of the effects of nuclear winter, whether the atmosphere would cleanse
itself in, say, weeks or months or whether it would take considerably
longer. This is a real issue, especially considering the self-lofting of soot,
which has been demonstrated in recent fully interactive general circulation
models, such as those of Malone and colleagues7 at Los Alamos National
Laboratory. Also, the earth's atmosphere is restructured by the heating
that occurs at high altitudes to produce a vast region of thermal inversion.
Working in the other direction is the fact that some soot but not dust
would be chemically attacked in the upper atmosphere, and so the chemical
properties, the absorption coefficients of the fine particles, may to some
extent decay with time.
There is a school of thought that says that as long as the effects of
nuclear winter are uncertain, they should not be seriously considered-
or at least they should not be taken into account in discussions of public
policy.8 It is a curious position because, among other reasons, the standard
military posture in thinking about He Soviet Union is the worst case
analysis. The argument is always that we must plan not on what the Soviet
Union is likely to do but what is the worst that they can possibly do. But
somehow that approach does not carry over, even a little bit, in the minds
of these people into assessments of the consequences of nuclear war. Here
it is argued just the other way around; that is, the best possible case should
be adopted as the basis for strategic policy and doctrine until it is un-
ambiguously demonstrated that a worse case is probable.
The issues of exactly how much the temperatures would fall and exactly
how much sunlight would be attenuated are, of course, uncertain. "Un-
certain" does not mean that we know nothing. Uncertain means simply
that we are not certain.* But even for relatively small nuclear wars,
involving roughly 1 percent of the 20,000 or so strategic warheads in the
U.S. and Soviet nuclear arsenals, the effects appear to be devastating-
especially if cities are targeted. What is especially relevant is the vul-
nerability of biological systems, including the webs of ecological inter-
dependence of which humans are a part, to even small temperature decl~nes
*Most estimates of nuclear winter continental temperature declines from ambient for a
midsummer central strategic exchange have remained around-10 to-25°C, beginning
with the original MAPS paper. Anspaugh (this volume) takes us to task for presenting
one-dimensional calculations for land and sea separately, although we explicitly indicated
that allowance for the thermal inertia of the oceans was likely to make "temperature
decreases in continental interiors . . . roughly 30% smaller than predicted here, and along
coastlines 70% smaller."
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558 LONG-TE~ CONSEQUENCES ID PROSPECTS FOR RECOVERY
declines smaller than many recent models, as well as the earlier TRAPS
models, suggest may be the case.
Food arrives on the table, or at least in the kitchen, and I often eat it.
Sometimes I go so far as to visit the grocery store or supermarket. But I
rarely trace back the sequence of events that begins in a furrowed field
or a water-covered paddy. Harwell presents in this volume a paper on the
ecological consequences of nuclear war. It is good to remember that crops
are tremendously vulnerable to temperature declines, because much of the
food we eat has arisen by a process of artificial selection over thousands
of years from plants that were originally tropical or semitropical varieties.
Their sensitivity to temperature is marked. The Royal Society of Canada
reports and the SCOPE/ENUWAR reports both describe how a temperature
decline of two or three centigrade degrees in Canada does very little to
harm the wheat and barley crops. But one additional degree a temper-
ature decline in the growing season that is very modest compared with
those that occur in many nuclear winter scenarios causes the crops to
fail altogether.
Global agriculture also requires many subsidies: pesticides, fertilizers,
seed stocks, fuel for tractors, and many other things. Those subsidies to
nations that are not engaged in the nuclear war, that are not in the northern
mid-latitude combat zone, would, of course, be cut off since they come
mainly from the industrialized, nuclear-capable targeted nations.
Therefore, for such distant countries, the implications for food are
serious even if no nuclear weapons fall on their territory. And this is not
just true in places where subsistence is marginal. A nation like Japan
imports more than 50 percent of its food supply. So in the unlikely case
that in a major nuclear war no targets in Japan were hit, and no significant
radioactive fallout arrived from China, and no nuclear winter effects oc-
curred in Japan itself, then the principal effects would be on food, fuel,
and other imports. But that in itself would be sufficient to induce starvation
on an unprecedented scale in Japan.
More generally, nations that have no part in the quarrel between the
United States and the Soviet Union (if there are any) and nations that are
far removed from the northern mid-latitude combat zone could nevertheless
be utterly destroyed in a nuclear war.9 This is part of the answer to the
question that I am sometimes asked: "What is new about nuclear winter?
We all knew we were going to die anyway." Those of us in the United
States and the Soviet Union perhaps imagined that we were going to die
anyway in a major nuclear war. But people elsewhere in the world imag-
ined that their fate would be quite different. Now it appears that we are
all at risk.
The SCOPE/ENUWAR report stresses that the carrying capacity of the
planetary environment is limited. The report does not guarantee that this
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559
s the consequence of nuclear war, but the following numbers they adduce
seem well worth pondering: If every nation were reduced to subsistence
on local agriculture, without the kinds of major subsidies from without
that I mentioned above, then the carrying capacity of the planet would be
a population only 10 percent that at present, some hundreds of millions
of people. If humans were to be reduced to living off natural ecosystems,
as our hunter-gatherer ancestors did, then another factor of 10 reduction
in the human population would immediately follow, so that 50 million or
so humans would be all that the planet could support. And this assumes
that there are no effects other than those from the destruction of agriculture,
that no one dies from blast, prompt ionizing radiation, fires, fallout,
disease, cold, dark, pyrotoxins, or an enhanced surface flux of solar
ultraviolet radiation.
Clearly, the agricultural consequences of nuclear war through starvation
are much more serious than had been suggested only a few years ago.
I was struck by a number of new findings presented in this volume: for
example, the analysis by Rotblat that the acute mean lethal dose for humans
(LDso) may be considerably less than was previously thought, provided
the other wartime stresses (but no ecological factors) are considered. I
was also struck by the findings of Greer and Rifkin on the vulnerability
of human T cells, and therefore of the human immune system, to the
various stresses, mainly radiation stresses, of nuclear war. This raises
another set of issues. Let me mention two of them.
First, if the dose required for radiation sickness and death goes down,
does the dose required to compromise the immune system also go down?
The answer seems to be that it does. The amount of prompt radioactive
fallout that is in the range, for example, in which the human immune
system would be compromised corresponds to what fraction of the area
of the northern mid-latitude combat zone? Some very quick and rough
estimates suggest that as much as one-third to one-half of the northern
mid-latitude land area might suffer radiation doses approaching 100 reds.
In the vivid phrase of Greer and Rifl`in, nuclear war carries with it a kind
of global case of acquired immune deficiency syndrome (AIDS).
The second issue is that of synergism, where the overall consequences
of several different environmental stresses can be more than the sum of
their parts. Let me give an example. Birds are differentially vulnerable
to temperature declines, low light levels, and high-radiation environments.
Insects are relatively invulnerable to those same environmental stresses.
Birds are one class of predators on insects. After a nuclear war, birds
would die but the insects would just close up shop for the winter. When
the fine particles producing nuclear winter fall out or are carried out of
the atmosphere and the conditions return more or less to normal, the insects
rub their eyes and go about their business, reproducing at an increased
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560 LONG-TERM CONSEQUENCES ID PROSPECTS FOR RECOVERY
rate. But insects are disease vectors. At the same time, human immune
systems would be compromised and sanitary systems and medical and
hospital systems would be severely attenuated. It seems likely that, under
these conditions, epidemics and pandemics would rage.
There are many other examples. Synergisms have not at all been ex-
amined in detail. This is generally difficult to do because ecosystems are
complicated. In virtually every case, but not in all cases, the synergisms
work to decrease, not increase, the likelihood of long-term survival of the
populations exposed to them.
I was asked to say something about the issue of extinction. It is hard,
of course, to be in any sense certain about it. The paper by Ehrlichi° and
19 others mainly biologists and ecologists that was published in De-
cember 1983, following publication of the TTAPS paper, stressed that at
least under some circumstances, the extinction of plants, animals, and
microorganisms might be expected. They went on to make a statement
that was properly cautious, that is, that the extinction of the human species
could not be excluded under these circumstances; however, they did not
say that it was guaranteed.
But extinction is the rule, not the exception, for life on Earth. By far,
most species that have ever existed are extinct today. There have been
massive species extinctions, including the extinctions at the Cretaceous-
Tertiary boundary 65 million years ago, in which most of the species of
life on Earth died out. It is at least a good Beth that the K-T extinctions
were produced by something like nuclear winter, caused by the impact
on the Earth of a 10-kilometer-diameter object, an asteroid or cometary
nucleus, that sprayed fine particles up into the atmosphere that took 1 or
2 years to fall out. There is one major difference: the dinosaurs were not
responsible for their own demise.
Now, there is an announced American plan the so-called national
program to study nuclear winter and its consequences. It was originally
advertised to be funded at $50 million for 5 years. The first year of funding,
however, turns out to be at a rate of $5.5 million, and much of that turns
out to be for programs that are not very different from those already
authorized before the discovery of nuclear winter. The research is very
highly concentrated in the Department of Defense and the national weapons
laboratories. Only $500,000 is allocated to the National Science Foun-
dation. There is an uncomfortable tendency for this very small amount of
money to go to institutions that may, more so than others, be captives of
what passes for the prevailing wisdom.
In addition, it is a matter of policy that virtually none of this money
goes for biological studies on the grounds that you have to be "sure"
of the post-war physical environment before you can trace the biological
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561
implications. Well, that is a prescription for never studying the biological
consequences at all. In contrast, a wide range of biological studies can
be done in which possible nuclear war effects are parameterized for
example, studies in which communities of organisms, biomes, are sub-
jected to a wide range of environmental stresses that would simulate
nuclear winter along with its collateral effects such as radioactivity, pyro-
toxins, and, later, enhanced UV-B flux. Such experiments would also be
of general ecological utility quite apart from the nuclear winter issue.
Another aspect of some of the papers presented in this volume that
struck me was the explicit or implicit seriousness of nuclear wars that fall
significantly short of engaging the full strategic arsenals. In the original
TTAPS nuclear winter study, ~ a heuristic calculation was performed for
a nuclear war scenario in which 100 downtowns were burned and nothing
else was destroyed. It would have required some 0.S percept of the strategic
arsenals and was shown to be enough to produce a very major nuclear
winter effect.
Here, Daugherty, Levi, and von Hippel also talked about the destruction
of 100 cities and found a trail of death and destruction resulting from
prompt effects alone to be much worse than had been discussed previously.
Abrams showed in many different ways the enormous disparity be-
tween the medical facilities that would be available after a nuclear war
and the urgent human needs that would actually exist. While there were
different proportional disparities, some of them-intensive care units and
especially burn beds- represented very large disparity factors: a factor of
100 or more for the Federal Emergency Management Agency (FEMA)
6,500-megaton attack scenario.
So, if there is, say, a factor of 100 disparity between what is available
and what would be needed for the survivors of a 6,500-megaton attack,
it is again possible to see that the consequences would be extremely serious
for something far less than a full exchange. Thus, it has been shown in
three different ways that the strategic arsenals are vastly- I would say
obscenely-in excess of what is necessary to produce unparalleled death
and destruction. This has a range of policy implications, including policy
implications for Star Wars, the Strategic Defense Initiative (SDI).
Even under very optimistic assessments, SDI leaks. These are not im-
permeable systems, and not even the most fervent technically competent
advocates of Star Wars foresee impermeable systems in the next two or
three decades. A system that is, for example, 10 percent permeable in a
contemporary full strategic nuclear exchange might let through as many
as a thousand and certainly a few hundred Soviet strategic warheads. This
is in the same ballpark as or in excess of the kinds of numbers mentioned
above. The U.S. and Soviet arsenals could be reduced by a factor of 10
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562 LONG-TERM CONSEQUENCES AND PROSPECTS FOR RECOVERY
to 100 and still retain for each nation an invulnerable and devastating
retaliatory capability, maintaining, if we think it desirable, the posture of
strategic deterrence.
The possible failures of human and technological systems, especially
under stress, also have been discussed in this volume. There is currently
a field of technology that is subject to a great deal of public scrutiny, in
which an enormous amount of national pride has been invested, in which
the best minds work, and for which the major nuclear nations have pow-
erfu] incentives not to have embarrassing failures: the civilian space pro-
gram. Nevertheless, there have always been and there remain major
unexpected failures at every level in the civilian space program. Just
recently there was the spectacle of French President Francis Mitterand
visiting French Guiana to witness a launch of an Ariane booster, which
promptly blew up on the pad. An even more famous case is when Soviet
Premier Nikita Khrushchev was at the United Nations in New York and
a spectacular launch was planned from Tyuratum. Instead there was a
spectacular explosion, which killed Field Marshal Nedelin and other mem-
bers of the upper echelons of Soviet rocketry senior management. The
explosion is easy to understand; that it killed a marshal is more difficult
to understand.
And the space shuttle itself has had many failures: in the deployment
of satellites, in its computers, and so on.* These examples are just re-
minders that technical failures are unavoidable, especially in a situation
in which there is insufficient opportunity for testing because, as has been
stated repeatedly, there can only be one nuclear war. There will not be
much opportunity to learn from experience.
I would like to make a few remarks about the section of this volume
on the psychosocial perspectives of images and risks of the nuclear arms
race. I thought that this was extraordinarily useful and is perhaps the
central topic of the nuclear war issue, namely, the human heart and mind.
In the late winter and early spring of 1902, on the island of Martinique,
there were a set of unmistakable premonitions of Me forthcoming volcanic
*Note added in proof, May 9, 1986: Since I gave this presentation on September 22,
1985, my point has been tragically reinforced by the Challenger disaster and several sub-
sequent NASA and DoD launch failures and, in the Soviet Union, by the Chernobyl disaster
(for which the probability of meltdown was authoritatively stated by Soviet experts in 1985
as O.0001/yr). With these sobering recent experiences before us, how sure are we of the
improbability of accidental nuclear war or, if nuclear war happens, that the long-term
consequences will fall short of the worst case? And if we are unsure, how should decisions
on policy and doctrine be skewed? Also, what do these experiences tell us about the ultimate
reliability of the proposed and vastly more complicated SDI systems?
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explosion of Mt. Pelee. There were rumblings heard all over the island.
There were ash deposits and a number of people on the island, including
scientists, spoke out and urged prompt evacuation.
But civil authorities reassured everyone that there was nothing to worry
about and vigorously opposed the idea of taking any precautions what-
soever. On May 8, 1902, the famous volcanic explosion occurred, which
killed the entire population of the port of St. Pierre (some 26,000 people),
except for a handful of prisoners in subterranean cells, and the like.
This is a dramatic illustration of denial: denial by public officials, denial
in the face of the clear public interest. I give this as an existence theorem
of what can happen, not hypothetically, but in the real world.
The psychiatric mechanisms that were discussed today denial, dis-
placement, and projection are not part of the lexicon of political debate
in this country or, indeed, as far as I know, anywhere else. And yet they
are central issues of our time, especially, but by no means exclusively,
for the nuclear war problem. Better education of national leaders and the
world public on the existence and force of such unconscious motivations
should have a high priority.
One of the principal difficulties of the nuclear war issue is a kind of
failure of the imagination; that is, most of us have not experienced a
nuclear war, and therefore it is hard to imagine. It has an abstract quality.
It seems unreal. The principal, most effective means of transcending that
failure of the imagination is to portray it in the news media, and especially
on television.
We have heard about The Day After, but The Day After was, of course,
a very bowdlerized version of nuclear war. The American Broadcasting
Company (ABC) executives thought that even a bowdlerized version was
too much for the American people and were unusually skittish and nenous
about showing it. A television program much closer to the realities of a
nuclear war for example, the British Broadcasting Corporation (BBC)
program Threads was widely considered to be too difficult for Ameri-
cans to see and was not shown by the commercial networks or even by
the Public Broadcasting System. Only Ted Turner and WTBS had the
courage to show it.
There is, here, an important tension between public education about
these unpleasant possibilities and the understandable wish to avoid feeling
rotten all the time. But it is essential that we understand what the stakes
are if there is to be any likelihood that we can reduce the prospects of
nuclear war.
It is noteworthy and surprising and distressing how infrequently tele-
vision or films portray a hopeful future for the human species. Most
television attempts to prognosticate what the future holds involve either
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564 LONG-TERM CONSEQUENCES AND PROSPECTS FOR RECOVERY
a very unimaginative extrapolation from where we are today and/or some
kind of global, usually nuclear, catastrophe. As a result, youngsters grow
up expecting the worst, without any knowledge that major departures from
the prevailing wisdom, in a benign direction, have occurred many times
before in human history. They can happen again.
There was a time when the divine right of kings was powerfully ad-
vocated, in which national leaders and the clergy argued, to take an
American example, that it was the specific intention of God Almighty
that Americans should live under the yoke of King George III. Well, we
now laugh at that. How could anyone have been so foolish as to believe
that George III was divinely foisted upon us? But there was a time when
the remark I have just made was treasonable.
The same is true of slavery, at least chattel slavery, in which people
were bought and sold like cattle. That was also considered divinely or-
dained. Aristotle argued that chattel slavery is part of human nature, some
humans (those in power) are "naturally" masters, others "naturally"
slaves. And yet today, all over the world, with only a few exceptions, it
is widely recognized that slavery is something monstrous; maybe our
ancestors were comfortable with such an institution, but we in the en-
lightened present recognize it for what it is.
Similar remarks apply to cannibalism, smallpox, and many other social
conventions and natural events that were once thought immutable. I sug-
gest that our descendants if we are wise enough to avoid the worst-
will look upon our tolerance of nuclear weapons, or willingness to "live"
with them, as we look on those tolerant of absolute monarchy or chattel
slavery. I suggest that the nuclear war issue, which seems to be such a
difficult nut to crack, also is a soluble problem, but only if, as Einstein
urged upon us, we are willing to change our way of thinking.
A ~ ~ ., . ·.
NOTES
Marco, R. P., O. B. Toon, T. P. Ackerman, J. B. Pollack, and C. Sagan. 1983. Nuclear
winter: Global consequences of multiple nuclear explosions. Science 222:1283-1292.
[TTAPS]
2National Research Council. Committee on the Atmospheric Effects of Nuclear Explo-
sions. 1985. The Effects on the Atmosphere of a Major Nuclear Exchange. Washington,
D.C.: National Academy Press.
3Royal Society of Canada. 1985. Nuclear Winter and Associated Effects: A Canadian
Appraisal of the Environmental Impact of Nuclear War. Ottawa: Royal Society of Canada.
4Alexandrov, V., Update of climatic impacts of nuclear exchange, International Seminar
on Nuclear War, Fourth Session, EIice, Italy, August 19-24, 1984; The Night After:
Climatic and Biological Consequences of a Nuclear War, 1985, Moscow: Mir; see also
Ehrlich, P. R., C. Sagan, D. Kennedy, and W. O. Roberts, 1984, The Cold and The Dark:
The World After Nuclear War, New York: W. W. Norton.
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sPittock, A. B., T. P. Ackerman, P. J. Crutzen, M. C. MacCracken, C. S. Shapiro, and
R. P. Turco, 1986, Environmental Consequences of Nuclear War, Vol. I: Physical and
Atmospheric Effects, New York: John Wiley & Sons; Harwell, M. A., and T. C. Hutch-
inson, 1986, Environmental Consequences of Nuclear War, Vol. II: Ecological and Ag-
ricultural Effects, New York: John Wiley & Sons; see also Sagan, C., 1985, Nuclear winter:
A report from the world scientific community, Environment 27(8):12-15,38-39.
6By S. Schneider in testimony, House Interior and Science and Technology Committees,
March 14, 1985. (Proceedings in press, U.S. Government Printing Office, Washington,
D.C.)
7Malone, R. L., L. H. Auer, G. A. Glatzmaier, M. C. Wood, and O. B. Toon. 1986.
Nuclear winter: Three-dimensional simulations including interactive transport, scavenging,
and solar heating of smoke. J. Geophys. Res., 91(D1):1059-1053; also see R. L. Malone,
Atmospheric perturbations of large-scale nuclear war. This volume.
8See, e.g., Teller, E., 1984, Widespread after-effects of nuclear war, Nature 310:621-
624; and the rebuttal, Sagan, C., 1985, On minimizing the consequences of nuclear war,
Nature 317:485-488.
9Sagan, C. Nuclear war and climatic catastrophe: Some policy implications. 1983/1984.
Foreign Affairs 62(2):257-292.
~°Ehrlich, P. R., et al. 1983. Long-term biological consequences of nuclear war. Science
222: 1293-1300.
~Sepkoski, J. John Jr. 1986. Phanerozoic overview of mass extinction, in Pattern and
Process in the History of Life, D. M. Raup and D. Jablonski (eds.). Berlin: Springer-
Verlag.
i2Alvarez, L. W., W. Alvarez, F. Asaro, and H. V. Michel, 1980, Extraterrestrial cause
for the cretaceous-tertiary extinction, Science 208: 1095; Pollack, J. B., O. B. Toon, T. P.
Ackerman, C. P. McKay, and R. P. Turco, 1983, Environmental effects of an impact-
generated dust cloud: Implications for the cretaceous-tertiary extinctions, Science 219:287.
Representative terms from entire chapter:
nuclear winter
