|
Items in cart [0] |
Questions? Call 888-624-8373 |
| Copyright © 2009. National Academy of Sciences. All rights reserved. Terms of Use and Privacy Statement |
Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter.
Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.
OCR for page 96
The Medical Implications of Nuclear War, Institute of
Medicine. @) 1986 by the National Academy of Sciences.
National Academy Press, Washington, D.C.
Recent Assessments of the Environmental
Consequences of Nuclear War
RICHARD P. TURCO, PH.D.
R&D Associates, Marina de! Rey, California
NEW FINDINGS
Since late 1984 a number of important scientific studies have considered
the global-scale consequences of a major nuclear war. These studies look
beyond the immediate and direct effects of nuclear explosions (blast,
thermal radiation, and local radioactive fallout) to investigate the more
widespread effects of dispersed radioactivity and severe climatic disturb-
ances the nuclear winter (Crutzen and Birks, 1982; Turco et al., 1983~.
Assessments of the relevant phenomena have been carried out by the U.S.
National Research Council (NRC, 1985), the Royal Society of Canada
(1985), and the Scientific Committee on Problems of the Environment
(SCOPE) of the International Council of Scientific Unions (Pittock et al.,
1986, Harwell and Hutchinson, 19851. Numerous physicists, atmospheric
scientists, biologists, and physicians from around the world have contrib-
uted to these projects. In each case the findings are similar. While cau-
tioning that significant uncertainties remain to be resolved, each report
concludes that a nuclear winter is a clear possibility following a nuclear
exchange. The SCOPE report goes even further, describing the biological,
ecological, and human implications of a nuclear war and its aftermath.
This unique treatise is summarized in the paper by M. Harwell in this
volume (also see Harwell and Hutchinson, 19854.
The SCOPE executive summary of findings on the physical and at-
mospheric effects of nuclear war is reproduced in the appendix to this
paper. The report confirms that the coexistence of immense nuclear ar
96
OCR for page 97
THE ENVIRONMENTAL CONSEQUENCES OF NUCLEAR WAR
97
senals (about 24,000 warheads carrying some 12,000 megatons of explo-
sives) and abundant combustible fuels concentrated in industrial and urban
areas (up to several thousand million tons of petroleum and petroleum
products and more than ten thousand million tons of wood and wood
products) could bring about a global nuclear winter in the event of nuclear
exchange. The physical mechanism would involve the ignition of large
fires by nuclear bursts, followed by the insertion of unprecedented quan-
tities of smoke into the atmosphere, where it could divert sunlight and
trigger climatic perturbations.
In addition to the major national and international studies mentioned
above, a number of important individual scientific contributions to the
nuclear winter problem have been made recently. Small and Bush (1985)
reassessed the potential quantity of fuel that might burn in nuclear deto-
nations over rural (nonurban) targets. They found quantities 10 to 100
times smaller than previous estimates (C~utzen and Birks, 1982; Turco et
al., 1983; NRC, 1985~. Although the methodology of the study by Small
and Bush is more thorough than earlier approaches, some of the key
assumptions have been questioned; a subsequent analysis increases the
fuel estimates of Small and Bush by a factor of about 10 (Pittock et al.,
1986~. Regardless of the resolution to this problem, wildland fire smoke
remains a secondary contributor to a nuclear winter, with industrial and
urban smoke being the primary contributor.
The heights of deposition of smoke in large fire plumes have been
studied by Cotton (1985) and Manins (19851. It now seems clear that
smoke from large nuclear-initiated fires would be injected into the upper
troposphere, with some directly reaching the stratosphere. Most of the
smoke injection would be above the low-altitude zone of normally rapid
washout. However, the fraction of the smoke that might be removed
immediately in the induced "black rain" is currently unknown; fractions
of 30 to 50 percent assumed in recent assessments seem reasonable (NRC,
1985; Pittock et al., 19861.
Even if the smoke is not initially injected into the stratosphere, several
new studies show that heating produced by the absorption of sunlight will
cause the smoke to rise into this region (Haberle et al., 19851. Such studies
also indicate that solar heating could lead to the stabilization of elevated
smoke layers and accelerate their spread into the Southern Hemisphere.
The result would be more widespread and prolonged climatic disturbances.
The expected climatic impacts of dense smoke layers include land sur-
face temperature decreases of up to 35°C within one week during the
summer half of the year, major shifts in global wind patterns, and sub-
stantial decreases in precipitation in many continental regions (Thompson,
1985; Cess et al., 1985; Malone et al., 19861. When proper comparisons
OCR for page 98
98
PHYSICAL EFFECTS AND ENVIRONMENTAL CONSEQUENCES
are made between these new results and the original nuclear winter cal-
culations of Turco et al. (1983), the predicted temperature declines are
found to be very similar.* The latest physical modeling of the radiative
and climatic effects of dense clouds of smoke (Cess et al., 1985; Covey
et al., 1985; Ramaswamy and Kiehl, 1985) reinforce the cooling mech-
anisms postulated for a nuclear winter.
In summary, a growing body of detailed technical analyses supports
the general principles of the nuclear winter theory. Thus, although sub-
stantial work remains to be done, the theory now stands on a much firmer
scientific basis than ever before. In light of these newest confirmations
of the possible physical aftermath of a major nuclear war, greater emphasis
should be placed on understanding the biological and ecological conse-
quences, particularly the agricultural and human impacts. These are, after
all, of the most urgent concern to the global community (Harwell and
Hutchinson, 19851.
POTENTIAL CONTRIBUTION OF PLASTICS TO
NUCLEAR WINTER
Modern civilization is finding more uses for plastics in construction,
durable goods, and packaging. When burned, plastics typically generate
a sooty toxic smoke (and could therefore contribute to a nuclear winter).
The industrialized world is producing plastics and noncellulosic synthetic
fibers at the rate of about 60 million metric tons, or teragrams ( 1 teragram
[Tg] = 10~2 g), per year (U.N. Statistical Yearbook, 1981; Handbook of
Economic Statistics, 19841. In the United States, plastics output is pro-
jected to increase by up to 5 to 6 percent per year through this decade
(U.S. Industrial Outlook, 19851. Worldwide output has grown roughly
10-fold over the last two decades, and at current rates of growth output
could redouble by the turn of the century. In 1983, production in the
North Atlantic Treaty Organization (NATO) and Warsaw Pact alliances
and Japan amounted to about 46 Tg of plastics and 8 Tg of noncellulosic
fibers. Plastics are derived primarily from petroleum and account for about
2 percent of total petroleum consumption.
The breakdown of production and usage for various plastics in the
United States is given in Table 1. Considering the 70 percent of all plastics
represented by the data in Table 1, about one-third goes into each of the
packaging and construction industries, about one-quarter into consumer
durables, and the rest into the transportation industry. These statistics are
*
That is, by taking into account the moderating effect of oceans on land temperatures
and the normal seasonal differences in initial land temperatures.
OCR for page 99
THE ENVIRONMENTAL CONSEQUENCES OF NUCLEAR WAR
TABLE 1 Plastics Production, Use, and Properties
99
Production/Usea (Tg/yr) Specific
Fraction of Extinction
Total Coefficient
Pack- Construc- Consumer Transpor- Production b of Smoke C
Plastics aging tion Durables tation Represented (m2/g-plastic)
Polyethylene 2.87 0.77 0.70 0.12 0.70 0.5
Polyvinylchloride 0.30 1.89 0.49 0.10 0.81 1.0
Polystyrene 0.74 0.15 0.48 0 0.63 1.5
Polypropylene 0.42 0.04 0.87 0.16 0.68 0.5
Polyurethane 0 0.18 0.39 0.19 0.86 0.5
Polyester 0.40 0.15 0.33 0.09 0.95 1.0
Phenolic 0 0.99 0.08 0 0.91 0.5
Acrylonitrile- 0 0.09 0.16 0.11 0.69 1.2
butadiene
styrene
Epoxy/Melamine 0 0.49 0.25 0 0.90 0.3
Total 4.73 4.75 3.75 0.77 0.703
Weighted
averagee
.'
SpeClIlC
extinction
coefficient of
smoke
(m2/g-plastic)
0.73 0.78 0.75 0.73
NOTE: Data on production and consumption apply to the United States in 1984 and are taken
from Modern Plastics (1985). Only the predominant families of plastics are considered.
aPackaging includes containers, wrappers, fillers, bottles, caps, cups, and so on. Construction
materials include pipes, panels, insulation, wiring, tiles, moldings, fixtures, and so forth. Con-
sumer durables include appliances, electronic gear, housewares, toys, records, tapes, and the
like. Transportation refers to plastics used in cars, trucks, buses, aircraft, and so on.
bThe fraction of production of each type of plastic that is included in the four use categories
(i.e., excluding miscellaneous uses for which statistics are unavailable and exports).
CThe specific extinction (scattering plus absorption) coefficients apply at visible wavelengths.
The values are based on laboratory data obtained from the references cited in the text, but have
a substantial uncertainty. (The coefficient for phenolics is only estimated.) The extinction coef-
ficient, when multiplied by the quantity of a particular type of plastic that may be burned, and
divided by the area over which the smoke may be dispersed, provides an estimate of the extinction
optical depth of the resulting smoke layer.
This is the fraction of the total production of plastics (all types and all uses) represented by
the data in the table. According to Modern Plastics (1985), total U.S. plastics consumption in
1984 was nearly 20 Tg.
eThe average extinction coefficient corresponding to the specific mix of plastics in each use
category.
OCR for page 100
100
PHYSICAL EFFECTS AND ENVIRONMENTAL CONSEQUENCES
consistent with other surveys of plastics consumption (U.S. Statistical
Abstracts, 19851.
There are two lifetimes of plastics that are of interest: their functional
lifetime from manufacture to disposal as trash and their lifetime in the
environment after disposal. It is assumed that plastics used in packaging
(about 33 percent of the total produced, or 16 Tg/year at present) have
an average functional lifetime of 3 months. Thus, relatively little packaging
material is stockpiled at any time. Of the remaining plastics, it is assumed
that equal thirds have functional lifetimes of 10, 20, and 40 years (i.e.,
about 22 percent of total production, or 10 Tg/year of each type at present).
The longer-lived materials would be used mainly in construction as well
as in certain items of furniture and appliances. In addition, poly-
meric fibers, used principally in carpeting, are assigned a lifetime of 10
years (8 Tg/year is produced at present). While the useful lifetimes of
plastics in society are difficult to determine accurately, our estimates based
on broad use categories should be adequate.
In disposal, plastics may be burned, buried, or simply discarded as
loose rubbish. Only about 10 percent of all collected municipal waste is
burned, and thus incineration represents a minor sink for plastics (Guillet.
19731. No meaningful recycling of plastics occurs. Most polymers are
also immune to decomposition in soils. However, solar ultraviolet radia-
tion causes bond incisions in many polymers, leading to chemical activity
and degradation, although continuous direct exposure to sunlight is re-
quired for effective decomposition (Guillet, 1973~. Today, discarded plas-
tics continue to accumulate in dumps, salvage yards, and landfills. Some
of this material would be accessible to burning in a nuclear war.
Production records indicate that about 750 Tg of plastics and noncel-
lulosic fibers were manufactured from 1963 to 1983 in the United States,
Europe, the USSR, and Japan. With the assumed lifetimes discussed
above, it is estimated that about 400 Tg of polymers are in use today.
Given the production rates and lifetimes of various plastics products
and the amounts available in 1983, estimates of future accumulations can
be made (Figure 11. If production were to remain constant at the 1983
level, the quantity of plastics in use would continue to grow, approaching
700 Tg in several decades. If production were to increase by 5 percent
per year until the turn of the century (as might be anticipated based on
past perfo~ance; U.S. Industrial Outlook, 1985), about 800 Tg could be
in use in the NATO and Warsaw Pact alliances by the turn of the century,
with the quantities in use in these countries continuing to grow well into
the century. Greater amounts would have been produced and discarded,
and much of this would be accessible at trash disposal sites. More than
1,600 Tg of plastics and fibers will have been manufactured in the countries
of interest by the turn of the century.
OCR for page 101
THE ENVIRONMENTAL CONSEQUENCES OF NUCLEAR WAR
4000 ' ' ' 1 ' ' ' ' 1 ' ' ' ' 1 ' 1' ' ' 1 ' ' ' '
// '
~ b , ~
In
m 3000
ILL
cam
o
J
z
o 2000
-
101
/
PRODUCED
-
-
I N USE
-
O.
1983 1993 2003 2013 2023 2033
YEAR
FIGURE 1 Projections of the total production and accumulation of plastics and
noncellulosic fibers in the United States, Europe, the U.S.S.R., and Japan. The
calculations correspond to the following assumptions about future plastics pro-
duction: (a) production is constant at the 1983 rate for an indefinite period, and
(b) production grows annually by 5 percent of the 1983 rate from 1983 to 2003
and is constant thereafter. The assumed plastics lifetimes are discussed in the text.
The smoke produced by burning polymers has been studied in the
laboratory (Tewarson, 1982; Seader and Einhorn, 1976; Morikawa, 1978;
Hilado and Machado, 1978; Quintiere, 1982; Bankston et al., 1981~. For
the materials in Table 1, measured smoke emission factors (grams of
smoke per gram of material burned) range from several percent to 20
percent or more. Under smoldering conditions, as much as 50 percent of
some plastics may be converted into smoke particles. Under flaming con-
ditions, the smoke is typically black and sooty, with a large optical ab-
sorption coefficient.
Table 1 summarizes data on the specific extinction coefficient of the
smoke generated by a variety of plastics during flaming combustion (the
specific extinction coefficient is expressed in terms of the square meters
of cross section produced by each gram of material burned). The values
for individual plastics differ by a factor of 5 or more. However, the average
weighted coefficients corresponding to the four principal use categories
in Table 1 are very similar. On this basis, a specific extinction coefficient
OCR for page 102
102
PHYSICAL EFFECTS AND ENVIRONMENTAL CONSEQUENCES
of 0.75 m2/g-plastics burned may be employed to make estimates of optical
effects.
Plastics can be treated with flame retardants and smoke retardants. In
the United States in 1984, 200,000 tons of flame retardants were used
(about 1 percent of the weight of the plastics produced) (Modern Plastics,
1984~. Flame retardants do not generally reduce the smoke emissions of
plastics and can increase emissions dramatically in some cases (Bankston
et al., 1981~. Practical and economical smoke retardants for plastics have
not yet been developed. Such retardants may eventually reduce the smoke
emissions of certain plastics by up to 50 percent (Modern Plastics, 1984)
but will never eliminate the smoke altogether.
Accumulated plastics are concentrated in urban zones where, because
of their variety, utility, and durability, they find countless practical uses.
In the United States, the top 277 metropolitan areas hold about 75 percent
of the population (U.S. Statistical Abstracts, 1985) and, presumably, at
least this fraction of all plastics. The bunting of hundreds of teragrarns of
plastics would produce enough sooty smoke to contribute to a nuclear
winter, perhaps even leading to one in the absence of other sources of
smoke and dust. Of course, a substantial portion of the urban areas of the
warring nations would have to be ignited in fires, as has been postulated
in a number of recent studies (Crutzen and Barks, 1982; Turco et al.
1983; NRC, 1985; Pittock et al., 1986~.
Table 2 defines a plausible range of optical perturbations that might
result from plastics combustion in a future nuclear war. The range of
potential global-average absorption optical depths resulting from plastics
smoke accounting for a plausible range of parameter variations is about
0.1 to 1.2. It has been shown that smoke injections leading to equivalent
global absorption optical depths of ~0.2 could greatly perturb the climate
(Thompson, 1985; Cess et al., 1985; Malone et al., 1986~. The baseline
scenario of Turco et al. (1983) projected an equivalent global absorption
TABLE 2 Projected Smoke Potential of Plastics in 2000 A.D.
Mass of Plastics (Tg)
Total Extinction Cross-section (1012 m2)
Fraction Activated by Firesa
Equivalent Global Extinction Optical Depthb
Global Absorption Optical DepthC
TTAPS Baseline Urban Smoke Absorption Optical Depth (global)
1,000-2,000
750- 1 ,500
118-1/2
0.2-1.5
0.1-1.2
~0.5
aThis factor assumes that one-fourth to two-thirds of all plastics in the warring nations could
be burned in a major nuclear war and that one-fourth to one-half of the smoke would be removed
immediately by precipitation (Pittock et al., 1986).
bThis assumes that the smoke is uniformly distributed around the entire planet.
CThis corresponds to a range of 0.2 to 0.5 for the single-scatter albedo of the smoke.
OCR for page 103
THE ENVIRONMENTAL CONSEQUENCES OF NUCLEAR WAR
103
optical depth of about 0.5, which produced a nuclear winter. Accordingly,
smoke and toxic gases from plastics alone would seem to guarantee some
nuclear winter-like environmental effects in the event of a future nuclear
conflict. Additional sources of climate-altenng aerosols would be soot
from oil and structure fires, smoke from wildfires, and dust from surface
detonations.
The estimates presented here are uncertain because, among other things,
extrapolations of trends in plastics consumption have been extended sev-
eral decades into the future. However, the drift toward greater worldwide
dependence on plastics and synthetic fibers is very clear. Nuclear arsenals
may be reduced substantially in the coming decades, but there is currently
little reason for optimism. Thus, in a politically divided world, we must
seriously consider how advanced technologies may someday interact to
threaten the future of mankind.
REFERENCES
Bankston, C. P., B. T. Zinn, R. F. Browner, and E. A. Powell. 1981. Aspects of the
mechanisms of smoke generation by burning materials. Comb. Flame 41:273-292.
Cess, R. D., G. L. Potter, S. J. Ghan, and W. L. Gates. 1985. The climatic effects of
large injections of atmospheric smoke and dust. J. Geophys. Res. 90:12937-12950.
Cotton, W. R. 1985. Atmospheric convection and nuclear winter. Am. Sci. 73:275-280.
Covey, C., S. L. Thompson, and S. H. Schneider. 1985. "Nuclear winter": A diagnosis
of atmospheric general circulation model simulations. J. Geophys. Res. 90:5615-5628.
Crutzen, P. J., and J. W. Birks. 1982. Twilight at noon: The atmosphere after a nuclear
war. Ambio 11:114-125.
Guillet, J. (ed.). 1973. Polymers and ecological problems. Polymer Science and Tech-
nology, Volume 3. New York: Plenum.
Haberle, R. M., T. P. Ackerman, O. B. Toon, and J. L. Hollingsworth. 1985. Global
transport of atmospheric smoke following a major nuclear exchange. Geophys. Res.
Lett. 12:405-408.
Handbook of Economic Statistics, 1984. 1984. Washington, D.C.: U.S. Government Print-
ing Office.
Harwell, M. A., and T. C. Hutchinson. 1985. Environmental Consequences of Nuclear
War, Volume II: Ecological and Agricultural Effects. SCOPE 28. Chichester, U.K.:
John Wiley & Sons.
Hilado, C. J., and A. M. Machado. 1978. Smoke studies with the Arapahoe chamber. J.
Fire Flammability 9:240-244.
Malone, R. C., L. H. Auer, G. A. Glatzmaier, M. C. Wood, and O. B. Toon. 1986.
Nuclear winter: Three-dimensional simulations including interactive transport, scaveng-
ing and solar heating of smoke. J. Geophys. Res. 91:1039-1053.
Manins, P. C. 1985. Cloud heights and stratospheric injections resulting from a thermo-
nuclear war. Atmos. Environ. 19: 1245- 1255.
Modern Plastics. 1984. 61:62-64.
Modern Plastics. 1985. Materials '85. 62:61-71.
Morikawa, T. 1978. Evolution of soot and polycyclic aromatic hydrocarbons in combustion.
J. Comb. Toxicol. 5:349-360.
OCR for page 104
104
PHYSICALEFFECTS AND ENVIRONMENTAL CONSEQUENCES
National Research Council (NRC). 1985. The effects on the atmosphere of a major nuclear
exchange. Washington, D.C.: National Academy Press.
Pittock, A. B., T. P. Ackerman, P. J. Crutzen, M. C. MacCracken, C. S. Shapiro, and
R. P. Turco. 1986. Environmental Consequences of Nuclear War, Volume I: Physical
and Atmospheric Effects. SCOPE 28. Chichester, U.K.: John Wiley & Sons.
Quintiere, J. G. 1982. An assessment of correlations between laboratory and full-scale
experiments for the FAA aircraft fire safety program. Part 1: Smoke. National Bureau
of Standards Report NB SIR 82-2508. Washington, D.C.: National Bureau of Standards.
Ramaswamy, V., and J. Kiehl. 1985. Sensitivities of the radiative forcing due to large
loadings of smoke and dust. J. Geophys. Res. 90:5597-5613.
Royal Society of Canada. 1985. Nuclear winter and associated effects: A Canadian appraisal
of the environmental impact of nuclear war. Ottawa, Canada: Royal Society of Canada.
Seader, J. D., and I. N. Einhon~. 1976. Some physical, chemical, toxicological and phys-
iological aspects of fire smokes. Pp. 1423-1445 in Proceedings of the 16th International
Symposium of the Combustion Institute, Pittsburgh, Pa.
Small, R. D., and B. W. Bush. 1985. Smoke production from multiple nuclear explosions
in nonurban areas. Science 229:465-469.
Tewarson, A. 1982. Experimental evaluation of flammability parameters of polymeric
materials. Pp. 97-153 in Flame Retardant Polymeric Materials, Vol. 3., M. Lewin,
S. M. Atlas, and E. M. Pierce, eds. New York: Plenum.
Thompson, S. L. 1985. Global interactive transport simulations of nuclear war smoke.
Nature 317:35-39.
Turco, 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.
U.N. Statistical Yearbook, 1979/1980. 1981. New York: United Nations.
U.S. Industrial Outlook, 1985. 1985. Washington, D.C.: Department of Commerce.
U.S. Statistical Abstracts 1984. 1985. Washington, I).C.: Department of Commerce.
APPENDIX
SCOPE/ENUWAR Executive Summary
The executive summary of the SCOPE (Scientific Committee on Prob-
lems of the Environment) ENUWAR (Environmental Effects of Nuclear
War) Report, Volume I: Physical and Atmospheric Effects (Pittock et al.,
1986), reviews the most important findings of recent detailed scientific
studies of the nuclear winter phenomenon (SCOPE 28, Volumes I and II,
John Wiley & Sons, Ltd., Chichester-available also from Wiley, Inc.
for North America). The summary is reproduced here in its entirety by
permission of SCOPE.
Executive Summary
This volume presents the results of an assessment of the climatic and
atmospheric effects of a large nuclear war. The chapters in the volume
follow a logical sequence of development, starting with discussions of
nuclear weapons effects and possible characteristics of a nuclear war. The
report continues with a treatment of the consequent fires, smoke emissions,
and dust injections and their effects on the physical and chemical processes
OCR for page 105
THE ENVIRONMENTAL CONSEQUENCES OF NUCLEAR WAR
105
of the atmosphere. This is followed by a chapter dealing with long-term
radiological doses. The concluding chapter contains recommendations for
future research and study.
In assessments of this type, a variety of procedural options are available,
including, for example, "worst case" analyses, risk analyses, and "most
probable" analyses. All of these approaches have relevance for the subject
addressed here due to the large uncertainties which surround many aspects
of the problem. Some of these uncertainties are inherent in studies of
nuclear war and some are simply the result of limited information about
natural physical processes. In general, in making assumptions about scen-
arios, models, and magnitudes of injections, and in estimating their at-
mospheric effects, an attempt has been made to avoid "minimum" and
"worst case" analyses in favor of a "middle ground" that encompasses,
with reasonable probability, the atmospheric and climatic consequences
of a major nuclear exchange.
The principal results of this assessment, arranged roughly in the same
order as the more detailed discussions contained in the body of this volume,
are summarized below. The Executive Summary of Volume II (Harwell
and Hutchinson, 1985), which describes the ecological and agricultural
consequences of a nuclear war, is included as Appendix 1 at the end of
this volume. A Glossary is included as Appendix 2 and a list of participants
in the study is included as Appendix 3.
1. DIRECT EFFECTS OF NUCLEAR EXPLOSIONS
The two comparatively small detonations of nuclear weapons in Japan
in 1945 and the subsequent higher yield atmospheric nuclear tests pre-
ceding the atmospheric test ban treaty of 1963 have provided some in-
formation on the direct effects of nuclear explosions. Typical modern
weapons carried by today's missiles and aircraft have yields of hundreds
~ . . . . · . . . .. ~ .
Of kilotons or more. ll detonated, such explosions WOU1O nave the ~o~-
lowing effects:
· In each explosion, thermal (heat) radiation and blast waves would
result in death and devastation over an area of up to 500 km2 per megaton
of yield, an area typical of a major city. The extent of these direct effects
depends on the yield of the explosion, height of burst, and state of the
local environment. The destruction of Hiroshima and Nagasaki by atomic
bombs near the end of World War II provides examples of the effects of
relatively small nuclear explosions.
· Nuclear weapons are extremely efficient incendiary devices. The
thermal radiation emitted by the nuclear fireball, in combination with the
accidental ignitions caused by the blast, would ignite fires in urban/in-
dustrial areas and wildlands of a size unprecedented in history. These fires
OCR for page 106
106
PHYSICAL EFFECTS AND ENVIRONMENTAL CONSEQUENCES
would generate massive plumes of smoke and toxic chemicals. The newly
recognized atmospheric effects of the smoke from a large number of such
fires are the major focus of this report.
~ For nuclear explosions that contact land surfaces (surface bursts),
large amounts (of the order of 100,000 tonne per megaton of yield) of
dust, soil, and debris are drawn up with the fireball. The larger dust
particles, carrying about half of the bomb's radioactivity, fall back to the
surface mostly within the first day, thereby contaminating hundreds of
square kilometers near and downwind of the explosion site. This local
fallout can exceed the lethal dose level.
· All of the radioactivity from nuclear explosions well above the surface
(airbursts) and about half of the radioactivity from surface bursts would
be lofted on particles into the upper troposphere or stratosphere by the
rising fireballs and contribute to longer term radioactive fallout on a global
scale.
· Nuclear explosions high in the atmosphere, or in space, would gen-
erate an intense electromagnetic pulse capable of inducing strong electric
currents that could damage electronic equipment and communications
networks over continent-size regions.
2. STRATEGIES AND SCENARIOS FOR A NUCLEAR WAR
In the forty years since the first nuclear explosion, the five nuclear
powers, but primarily the U.S. and the U.S.S.R., have accumulated very
large arsenals of nuclear weapons. It is impossible to forecast in detail
the evolution of potential military conflicts. Nevertheless, enough of the
general principles of strategic planning have been discussed that plausible
scenarios for the development and immediate consequences of a large-
scale nuclear war can be derived for analysis.
~ NATO and Warsaw Pact nuclear arsenals include about 24,000 stra-
tegic and theatre nuclear warheads totaling about 12,000 megatons. The
arsenals now contain the equivalent explosive power of about one million
"Hiroshima-size" bombs.
· A plausible scenario for a global nuclear war could involve on the
order of 6000 Mt divided between more than 12,000 warheads. Because
of its obvious importance, the potential environmental consequences of
an exchange of roughly this size are examined. The smoke-induced at-
mospheric consequences discussed in this volume are, however, more
dependent on the number of nuclear explosions occurring over cities and
industrial centers than on any of the other assumptions of the particular
exchange.
OCR for page 107
THE ENVIRONMENTAL CONSEQUENCES OF NUCLEAR WAR
107
· Many targets of nuclear warheads, such as missile silos and some
military bases, are isolated geographically from population centers. Never-
theless, enough important military and strategic targets are located near
or within cities so that collateral damage in urban and industrial centers
from a counterforce nuclear strike could be extensive. As a result, even
relatively limited nuclear attacks directed at military-related targets could
cause large fires and smoke production.
· Current strategic deterrence policies imply that, in an escalating nu-
clear conflict, many warheads might be used directly against urban and
industrial centers. Such targeting would have far-reaching implications
because of the potential for fires, smoke production, and climatic change.
3. THE EXTENT OF FIRES AND GENERATION OF SMOKE
During World War II, intense city fires covering areas as large as 10
to 30 square kilometers were ignited by massive incendiary bombing raids,
as well as by the relatively small nuclear explosions over Hiroshima and
Nagasaki. Because these fires were distributed over many months, the
total atmospheric accumulation of smoke generated by these fires was
small. Today, in a major nuclear conflict, thousands of very intense fires,
each covering up to a few hundred kilometers, could be ignited simul-
taneously in urban areas, fossil fuel processing plants and storage depots,
wildlands, and other locations. Because there have never been fires as
large and as intense as may be expected, no appropriate smoke emission
measurements have been made. Estimates of emissions from such fires
rely upon extrapolation from data on much smaller fires. This procedure
may introduce considerable error in quantifying smoke emissions, espe-
cially in making estimates for intense fire situations.
· About 70% of the populations of Europe, North America and the
Soviet Union live in urban and suburban areas covering a few hundred
thousand square kilometers and containing more than ten thousand million
tonne of combustible wood and paper. If about 25-30% of this were to
be ignited, in just a few hours or days, tens of millions to more than a
hundred million tonne of smoke could be generated. About a quarter to
a third of the emitted smoke from the flaming combustion of this material
would be amorphous elemental carbon, which is black and efficiently
absorbs sunlight.
· Fossil fuels (e.g., oil, gasoline, and kerosene) and fossil fuel-derived
products (including plastics, rubber, asphalt, roofing materials, and or-
ganochemicals) are heavily concentrated in cities and industrial areas;
flaming combustion of a small fraction (~25-30%) of the few thousand
OCR for page 108
108
PHYSICAL EFFECTS AND ENVIRONMENTAL CONSEQUENCES
million tonne of such materials currently available could generate 50-150
million tonne of very sooty smoke containing a large fraction (50% or
greater) of amorphous elemental carbon. The burning of 25-30% of the
combustible materials of the developed world could occur with near total
burnout of less than one hundred of the largest industrialized urban areas.
· Fires ignited in forests and other wildlands could consume tens to
hundreds of thousands of square kilometers of vegetation over days to
weeks, depending on the state of the vegetation, and the extent of fire-
spread. These fires could produce tens of millions of tonne of smoke in
the summer half of the year, but considerably less in the winter half of
the year. Because wildland fire smoke contains only about 10% amorphous
elemental carbon, it would be of secondary importance compared to the
smoke created by urban and industrial fires, although its effects would
not be negligible.
· The several tens of millions of tonne of sub-micron dust particles
that could be lofted to stratospheric altitudes by surface bursts could reside
in the atmosphere for a year or more. The potential climatic effects of the
dust emissions, although substantially less than those of the smoke, also
must be considered.
4. THE EVOLUTION AND RADIATIVE EFFECTS OF
THE SMOKE
The sooty smoke particles rising in the hot plumes of large fires would
consist of a mixture of amorphous elemental carbon, condensed hydro-
carbons, debris particles, and other substances. The amount of elemental
carbon in particles with effective spherical diameters on the order of 0.1
,um to perhaps 1.0 Am would be of most importance in calculating the
potential effect on solar radiation. Such particles can be spread globally
by the winds and remain suspended for days to months.
· Large hot fires create converging surface winds and rapidly rising
fire plumes which, within minutes, can carry smoke particles, ash and
other fire products, windblown debris, and water from combustion and
the surrounding air to as high as 10-15 kilometers. The mass of particles
deposited aloft would depend on the rate of smoke generation, the intensity
of the fire, local weather conditions, and the effectiveness of scavenging
processes in the convective column.
· As smoke-laden, heated air from over the fire rises, adiabatic ex-
pansion and entrainment would cause cooling and condensation of water
vapor that could lead, in some cases, to the formation of a cumulonimbus
cloud system. Condensation-induced latent heating of the rising air parcels
OCR for page 109
THE ENVIRONMENTAL CONSEQUENCES OF NUCLEAR WAR
109
would help to loft the smoke particles to higher altitudes than expected
from the heat of combustion alone.
~ Although much of the water vapor drawn up from the boundary layer
would condense, precipitation might form for only a fraction of the fire
plumes. In the rising fire columns of such fires, soot particles would tend
to be collected inefficiently by the water in the cloud. Smoke particles
however, are generally composed of a mixture of substances and might,
at least partially, be incorporated in water droplets or ice particles by
processes not now well understood. Smoke particles that are captured
could again be released to the atmosphere as the ice or water particles
evaporate in the cloud anvils or in the environment surrounding the con-
vective clouds. Altogether, an unknown fraction of the smoke entering
the cloud would be captured in droplets and promptly removed from the
atmosphere by precipitation.
· Not all fires would, however, induce strong convective activity. This
depends on fuel loading characteristics and meteorological conditions. It
is assumed in current studies that 30-50% of the smoke injected into the
atmosphere from all fires would be removed by precipitation within the
first day, and not be available to affect longer-term large-scale, meteor-
ological processes. This assumption is a major uncertainty in all current
assessments. For the fire and smoke assumptions made in this study, the
net input of smoke to the atmosphere after early scavenging is estimated
to range from 50 to 150 million tonne, containing about 30 million tonne
of amorphous elemental carbon.
· Smoke particles generated by urban and fossil fuel fires would be
strong absorbers of solar radiation, but would be likely to have compar-
atively limited effects on terrestrial longwave radiation, except perhaps
under some special circumstances. If 30 million tonne of amorphous el-
emental carbon were produced by urban/industrial fires and spread over
Northern Hemisphere mid-latitudes, the insolation at the ground would
be reduced by at least 90%. The larger quantities of smoke that are possible
in a major nuclear exchange could reduce light levels under dense patches
to less than 1% of normal, and, on a daily average, to just several percent
of normal, even after the smoke has spread widely.
~ Because of the large numbers of particles in the rising smoke plumes
and the very dense patches of smoke lasting several days thereafter, co-
agulation (adhering collisions) would lead to formation of fewer, but
somewhat larger, particles. Coagulation of the particles could also occur
as a result of coalescence and subsequent evaporation of rain droplets or
ice particles. Because optical properties of aerosols are dependent on
particle size and morphology, the aggregated aerosols may have different
optical properties than the initial smoke particles, but the details, and even
OCR for page 110
110
PHYSICAL EFFECTS AND ENVIRONMENTAL CONSEQUENCES
the sign, of such changes are poorly understood. The optical properties
of fluffy soot aggregates that may be formed in dense oil plumes, however,
seem to be relatively insensitive to their size. This is not the case for more
consolidated particle agglomerates.
· Little consideration has yet been given to the possible role of me-
teorological processes on domains between fire plume and continental
scales. Mesoscale and synoptic-scale motions might significantly alter,
mix, or remove the smoke particles during the first several days. Studies
to examine quantitatively the microphysical evolution of smoke particles
during this period are needed. While changes in detailed understanding
are expected, a significant fraction of the injected smoke particles is likely
to remain in the atmosphere and affect the large-scale weather and climate.
5. SMOKE-INDUCED ATMOSPHERIC PERTURBATIONS
In a major nuclear war, continental scale smoke clouds could be gen-
erated within a few days over North America, Europe, and much of Asia.
Careful analysis and a hierarchy of numerical models (ranging from one-
dimensional gIobal-average to ~ree-dimensional gIobal-scale models) have
been used to estimate the transport, transformation, and removal of the
smoke particles and the effects of the smoke on temperature, precipitation,
winds, and other important atmospheric properties. All of the simulations
indicate a strong potential for large-scale weather disruptions as a result
of the smoke injected by extensive post-nuclear fires. These models,
however, still have important simplifications and uncertainties that may
affect the fidelity and the details of their predictions. Nonetheless, these
uncertainties probably do not affect the general character of the calculated
atmospheric response.
· For large smoke injections reaching altitudes of several kilometers
or more and occurring from spring through early fall in the Northern
Hemisphere, average land surface temperatures beneath dense smoke patches
could decrease by 20-40°C below normal in continental areas within a
few days, depending on the duration of the dense smoke pall and the
particular meteorological state of the atmosphere. Some of these patches
could be carried long distances and create episodic cooling. During this
initial period of smoke dispersion, anomalies could be spatially and tem-
porally quite variable while patchy smoke clouds strongly modulate the
insolation reaching the surface.
· Smoke particles would be spread throughout much of the Northern
Hemisphere within a few weeks, although the smoke layer would still be
OCR for page 111
THE ENVIRONMENTAL CONSEQUENCES OF NUCLEAR WAR
111
far from homogeneous. For spring to early fall injections, solar heating
of the particles could rapidly warm the smoke layer and lead to a net
upward motion of a substantial fraction of the smoke into the upper tro-
posphere and stratosphere. The warming of these elevated layers could
stabilize the atmosphere and suppress vertical movement of the air below
these layers, thereby extending the lifetime of the particles from days to
perhaps several months or more.
· Average summertime land surface temperatures in the Northern
Hemisphere mid-latitudes could drop to levels typical of fall or early winter
for periods of weeks or more with convective precipitation being essen-
tially eliminated, except possibly at the southern edge of the smoke pall.
Cold, near-surface air layers might lead initially to fog and drizzle, es-
pecially in coastal regions, lowland areas, and river valleys. In continental
interiors, periods of very cold, mid-winter-like temperatures are possible.
In winter, light levels would be strongly reduced, but the initial temper-
ature and precipitation perturbations would be much less pronounced and
might be essentially indistinguishable in many areas from severe winters
currently experienced from time to time. However, such conditions would
occur simultaneously over a large fraction of the mid-latitude region of
the Northern Hemisphere and freezing cold air outbreaks could penetrate
southward into regions that rarely or never experience frost conditions.
· In Northern Hemisphere subtropical latitudes, temperatures in any
season could drop well below typical cool season conditions for large
smoke injections. Temperatures could be near or below freezing in regions
where temperatures are not typically strongly moderated by warming in-
fluence from the oceans. The connectively driven monsoon circulation,
which is of critical importance to subtropical ecosystems, agriculture, and
is the main source of water in these regions, could be essentially elimi-
nated. Smaller scale, coastal precipitation might, however, be initiated.
· Strong solar heating of smoke injected into the Northern Hemisphere
between April and September would carry the smoke upwards and equa-
torward, strongly augmenting the normal high altitude flow to the Southern
Hemisphere (where induced downward motions might tend to slightly
suppress precipitation). Within one or two weeks, thin, extended smoke
layers could appear in the low to mid-latitude regions of the Southern
Hemisphere as a precursor to the development of a more uniform veil of
smoke with a significant optical depth (although substantially smaller than
in the Northern Hemisphere). The smoke could induce modest cooling of
land areas not well buffered by air masses warmed over nearby ocean
areas. Since mid-latitudes in the Southern Hemisphere would already be
experiencing their cool season, temperature reductions would not likely
OCR for page 112
112
PHYSICAL EFFECTS AND ENVIRONMENTAL CONSEQUENCES
be more than several degrees. In more severe, but less probable, smoke
injection scenarios, climatic effects in the Southern Hemisphere could be
enhanced significantly, particularly during the following austral spring
and summer.
· Much less analysis has been made of the atmospheric perturbations
following the several week, acute climatic phase subsequent to a nuclear
war involving large smoke injections. Significant uncertainties remain
concerning processes governing the longer-term removal of smoke par-
ticles by precipitation scavenging, chemical oxidation, and other physical
and chemical factors. The ultimate fate of smoke particles in the perturbed
atmospheric circulation is also uncertain, both for particles in the sunlit
and stabilized upper troposphere and stratosphere and in the winter polar
regions, where cooling could result in subsidence that could move particles
downward from the stratosphere to altitudes where they could later be
scavenged by precipitation.
O Present estimates suggest that smoke lofted to levels (either directly
by fire plumes or under the influence of solar heating) which are, or
become, stabilized, could remain in the atmosphere for a year or more
and induce long-term (months to years) global-scale cooling of several
degrees, especially after the oceans have cooled significantly. For such
conditions, precipitation could also be reduced significantly. Reduction
of the intensity of the summer monsoon over Asia and Africa could be a
particular concern. Decreased ocean temperatures, climatic feedback
mechanisms (e.g., ice-albedo feedback), and concurrent ecological changes
could also prolong the period of meteorological disturbances.
6. ATMOSPHERIC CHEMISTRY IN A
POST-NUCLEAR-WAR ENVIRONMENT
Nuclear explosions and the resultant fires could generate large quantities
of chemical compounds that might themselves be toxic. In addition, the
chemicals could alter the atmospheric composition and radiative fluxes in
ways that could affect human health, the biosphere, and the climate.
~ Nitrogen oxides (NOx) created by nuclear explosions of greater than
several hundred kilotons would be lofted into the stratosphere. Depending
on the total number of high yield weapons exploded, the NOX would
catalyze chemical reactions that, within a few months time, could reduce
Northern Hemisphere stratospheric ozone concentrations by 10 to 30% in
an atmosphere free of aerosols. Recovery would take several years. How
OCR for page 113
THE ENVIRONMENTAL CONSEQUENCES OF NUCLEAR WAR
113
ever, if the atmosphere were highly perturbed due to smoke heating and
by injection of gaseous products from fires, the long-term ozone changes
could be enhanced substantially in ways that cannot yet be predicted.
· Ozone reductions of tens of percent could increase surface intensities
of biologically-active ultraviolet (UV) radiation by percentages of up to
a few times as much. The presence of smoke would initially prevent UV-
radiation from reaching the surface by absorbing it. The smoke, however,
might also prolong and further augment the long-term ozone reduction as
a result of smoke-induced lofting of soot and reactive chemicals, conse-
quent heating of the stratosphere, and the occurrence of additional chemical
reactions.
· Large amounts of carbon monoxide, hydrocarbons, nitrogen and sul-
fur oxides, hydrochloric acid, pyrotoxins, heavy metals, asbestos, and
other materials would be injected into the lower atmosphere near the
surface by flaming and smoldering combustion of several thousand million
tonne of cellulosic and fossil fuel products and wind-blown debris. Before
deposition or removal, these substances, some of which are toxic, could
be directly and/or indirectly harmful to many forms of life. In addition,
numerous toxic chemical compounds could be released directly into the
environment by blast and spillage, contaminating both soil and water.
This complex and potentially very serious subject has so far received only
cursory consideration.
· If the hydrocarbons and nitrogen oxides were injected into an oth-
erwise unperturbed troposphere, they could enhance average background
ozone concentrations several-fold. Such ozone increases would not sig-
nif~cantly offset the stratospheric ozone decrease, which also would be
longer lasting. It is highly questionable, however, whether such large
ozone increases could indeed occur in the presence of smoke because
ozone generation in the troposphere requires sunlight as well as oxides of
nitrogen. It is possible that, in the smoke perturbed atmosphere, the fire-
generated oxides of nitrogen could be removed before photochemical
ozone production could take place.
· Precipitation scavenging of nitrogen, sulfur, and chlorine compounds
dispersed by the fire plumes throughout the troposphere could increase
rainfall acidity by about an order of magnitude over large regions for up
to several months. This increased acidity could be neutralized to some
degree by alkaline dust or other basic (as opposed to acidic) compounds.
· Rapid smoke-induced cooling of the surface under dense smoke clouds
could induce the formation of shallow, stable cold layers that might trap
chemical emissions from prolonged smoldering fires near the ground. In
such layers, concentrations of CO, HC1, pyrotoxins, and acid fogs could
OCR for page 114
114
PHYSICAL EFFECTS AND EN1fIRONMENTAL CONSEQUENCES
reach dangerous levels. The potential for local and regional effects in areas
such as populated lowland areas and river valleys merits close attention.
7. RADIOLOGICAL DOSE
Near the site of an explosion, the health effects of prompt ionizing
radiation from strategic nuclear warheads would be overshadowed by the
effects of the blast and thermal radiation. However, because nuclear ex-
plosions create highly radioactive fission products and the emitted neutrons
may also induce radioactivity in initially inert material near the detonation,
radiological doses would be delivered to survivors both just downwind
(local fallout) and out to hemispheric and global scales (global fallout).
· Local fallout of relatively large radioactive particles lofted by the
number of surface explosions in the scenario postulated in this study could
lead to lethal external gamma-ray doses (assuming no protective action is
taken) during the first few days over about 7 percent of the land areas of
the NATO and Warsaw Pact countries. Areas downwind of missile silos
and other hardened targets would suffer especially high exposures. Sur-
vivors outside of lethal fallout zones could still receive debilitating radia-
tion doses (exposure at half the lethal level can induce severe radiation
sickness). In combination with other injures or stresses, such doses could
increase mortality. If large populations could be mobilized to move from
highly radioactive zones or take substantial protective measures, the human
impact of fallout could be greatly reduced.
· The uncertainty in these calculations of local fallout is large. Doses
and areas for single nuclear explosions could vary by factors of 2-4
depending on meteorological conditions and assumptions in the models.
A detailed treatment of overlapping fallout plumes from multiple explo-
sions could increase the areas considerably (by a factor of 3 in one sample
case). Results are also sensitive to variations in the detonation scenario.
· Global fallout following the gradual deposition of the relatively small
radioactive particles created by strategic air and surface bursts could lead
to average Northern Hemisphere lifetime external gamma ray doses on
the order of 10 to 20 reds. The peak values would lie in the northern mid-
latitudes where the average doses for the scenarios considered would be
about 20 to 60 reds. Such doses, in the absence of other stresses, would
be expected to have relatively minor carcinogenic and mutagenic effects
(i.e., increase incidence at most a few percent above current levels).
Smoke-induced perturbations that tend to stabilize the atmosphere and
slow deposition of radioactive particles might reduce these estimated av-
erage doses by perhaps 15%.
OCR for page 115
THE ENVIRONMENTaL CONSEQUENCES OF NUCLEAR WAR
115
· Intermediate time scale and long term global fallout would be de-
posited unevenly, largely because of meteorological effects, leading to
"hotshots" of several hundred thousand square kilometers in which av-
erage doses could be as high as 100 reds, and, consequently, large areas
where doses would be lower than the average value.
· In the Southern Hemisphere and tropical latitudes, global fallout
would produce much smaller, relatively insignificant, radiological doses
about one-twentieth those in the Northern Hemisphere, even if cross-
equatorial transport were accelerated by the smoke clouds. Additional
local fallout would be important only within a few hundred kilometers
downwind of any surface burst in the Southern Hemisphere.
· Additional considerations not factored into the above estimates are
possible from several sources. Doses from ingestion or inhalation of ra-
dioactive particles could be important, especially over the longer term.
Beta radiation could have a significant effect on the biota coming into
contact with the local fallout. Fission fractions of smaller modern weapons
could be twice the assumed value of 0.5; adding these to the scenario mix
could cause a 20% increase in areas of lethal fallout. General tactical and
theater nuclear weapons, ignored in these calculations, could also cause
a 20% increase in lethal local fallout areas in certain geographical regions,
particularly in Europe. The injection into the atmosphere of radionuclides
created and stored by the civilian nuclear power industry and military
reactors, a possibility considered remote by some, could increase estimates
of long-term local and global radiological doses to several times those
estimated for weapons alone.
8. TASKS FOR THE FUTURE
Extensive research and careful assessment over the past few years have
indicated that nuclear war has the potential to modify the physical envi-
ronment in ways that would dramatically impair biological processes. The
perturbations could impact agriculture, the proper functioning of natural
ecosystems, the purity of essential air and water resources, and other
important elements of the global biosphere. Because current scientific
conclusions concerning the response of the atmosphere to the effects of
nuclear war include uncertainties, research can and should be undertaken
to reduce those uncertainties that are accessible to investigation.
~ Laboratory and field experiments are needed to improve estimates of
the amount and physical characteristics of the smoke particles that would
be produced by large fires, particularly by the combustion of fossil fuels
and fossil fuel-derived products present in urban and industrial regions.
. .
OCR for page 116
116
PHYSICAL EFFECTS AND ENVIRONMENTAL CONSEQUENCES
Experimental conditions should be designed to emulate as much as possible
the effects of large-scale fires.
· Laboratory, field, and theoretical studies are needed to determine the
potential scavenging rates of smoke particles in the convective plumes of
large fires and the scavenging processes that operate on intermediate and
global scales as the particles disperse.
· Further theoretical calculations of the seasonal response of the at-
mosphere to smoke emissions from large fires are needed, particularly of
the extent of the perturbation to be expected at early times, when the
smoke is freshly injected and patchy. Simulations must be made for later
times from months to a year or more, when the atmosphere has been
highly perturbed and a substantial fraction of the smoke may have been
lofted to high altitudes. Closer attention should be paid to He possible
effects in low latitudes and in the Southern Hemisphere, where the climatic
effects are likely to be much more important than the direct effects of the
nuclear detonations, which are expected to be confined largely to the
Northern Hemisphere. ~
· Laboratory and theoretical studies are needed of the potential chem-
ical alterations of the atmosphere on global and local scales, and of the
extent that smoke particles could affect and might be removed by chemical
reactions high in the atmosphere.
· Radiological calculations should be undertaken using models that
more realistically treat the overlap of fallout plumes, complex meteoro-
logical conditions, and that consider both external and internal doses.
Patterns of land use and likely targeting strategy should be used in esti-
mating the potential significance of various scenarios. The question of the
possible release of radioactivity from nuclear fuel cycle facilities in a
nuclear war should be explored more thoroughly.
Representative terms from entire chapter:
environmental consequences
