WORLDWIDE EFFECTS OF NUCLEAR WAR - - - SOME PERSPECTIVES

U.S. Arms Control and Disarmament Agency, 1975.



CONTENTS



Foreword

Introduction

The Mechanics of Nuclear Explosions

Radioactive Fallout

A. Local Fallout

B. Worldwide Effects of Fallout

Alterations of the Global Environment

A. High Altitude Dust

B. Ozone

Some Conclusions

Note 1: Nuclear Weapons Yield

Note 2: Nuclear Weapons Design

Note 3: Radioactivity

Note 4: Nuclear Half-Life

Note 5: Oxygen, Ozone and Ultraviolet Radiation



FOREWORD



Much research has been devoted to the effects of nuclear weapons. But

studies have been concerned for the most part with those immediate

consequences which would be suffered by a country that was the direct

target of nuclear attack. Relatively few studies have examined the

worldwide, long term effects.

Realistic and responsible arms control policy calls for our knowing more

about these wider effects and for making this knowledge available to the

public. To learn more about them, the Arms Control and Disarmament Agency

(ACDA) has initiated a number of projects, including a National Academy of

Sciences study, requested in April 1974. The Academy's study, Long-Term

Worldwide Effects of Multiple Nuclear Weapons Detonations, a highly

technical document of more than 200 pages, is now available. The present

brief publication seeks to include its essential findings, along with the

results of related studies of this Agency, and to provide as well the basic

background facts necessary for informed perspectives on the issue.

New discoveries have been made, yet much uncertainty inevitably persists.

Our knowledge of nuclear warfare rests largely on theory and hypothesis,

fortunately untested by the usual processes of trial and error; the

paramount goal of statesmanship is that we should never learn from the

experience of nuclear war.

The uncertainties that remain are of such magnitude that of themselves they

must serve as a further deterrent to the use of nuclear weapons. At the

same time, knowledge, even fragmentary knowledge, of the broader effects of

nuclear weapons underlines the extreme difficulty that strategic planners

of any nation would face in attempting to predict the results of a nuclear

war. Uncertainty is one of the major conclusions in our studies, as the

haphazard and unpredicted derivation of many of our discoveries emphasizes.

Moreover, it now appears that a massive attack with many large-scale

nuclear detonations could cause such widespread and long-lasting

environmental damage that the aggressor country might suffer serious

physiological, economic, and environmental effects even without a nuclear

response by the country attacked.

An effort has been made to present this paper in language that does not

require a scientific background on the part of the reader. Nevertheless it

must deal in schematized processes, abstractions, and statistical

generalizations. Hence one supremely important perspective must be largely

supplied by the reader: the human perspective--the meaning of these

physical effects for individual human beings and for the fabric of

civilized life.

Fred C. Ikle

Director

U.S. Arms Control and Disarmament Agency



INTRODUCTION



It has now been two decades since the introduction of thermonuclear fusion

weapons into the military inventories of the great powers, and more than a

decade since the United States, Great Britain, and the Soviet Union ceased

to test nuclear weapons in the atmosphere. Today our understanding of the

technology of thermonuclear weapons seems highly advanced, but our

knowledge of the physical and biological consequences of nuclear war is

continuously evolving.

Only recently, new light was shed on the subject in a study which the Arms

Control and Disarmament Agency had asked the National Academy of Sciences

to undertake. Previous studies had tended to focus very largely on

radioactive fallout from a nuclear war; an important aspect of this new

study was its inquiry into all possible consequences, including the effects

of large-scale nuclear detonations on the ozone layer which helps protect

life on earth from the sun's ultraviolet radiations. Assuming a total

detonation of 10,000 megatons--a large-scale but less than total nuclear

"exchange," as one would say in the dehumanizing jargon of the

strategists--it was concluded that as much as 30-70 percent of the ozone

might be eliminated from the northern hemisphere (where a nuclear war would

presumably take place) and as much as 20-40 percent from the southern

hemisphere. Recovery would probably take about 3-10 years, but the

Academy's study notes that long term global changes cannot be completely

ruled out.

The reduced ozone concentrations would have a number of consequences

outside the areas in which the detonations occurred. The Academy study

notes, for example, that the resultant increase in ultraviolet would cause

"prompt incapacitating cases of sunburn in the temperate zones and snow

blindness in northern countries . . "

Strange though it might seem, the increased ultraviolet radiation could

also be accompanied by a drop in the average temperature. The size of the

change is open to question, but the largest changes would probably occur at

the higher latitudes, where crop production and ecological balances are

sensitively dependent on the number of frost-free days and other factors

related to average temperature. The Academy's study concluded that ozone

changes due to nuclear war might decrease global surface temperatures by

only negligible amounts or by as much as a few degrees. To calibrate the

significance of this, the study mentioned that a cooling of even 1 degree

centigrade would eliminate commercial wheat growing in Canada.

Thus, the possibility of a serious increase in ultraviolet radiation has

been added to widespread radioactive fallout as a fearsome consequence of

the large-scale use of nuclear weapons. And it is likely that we must

reckon with still other complex and subtle processes, global in scope,

which could seriously threaten the health of distant populations in the

event of an all-out nuclear war.

Up to now, many of the important discoveries about nuclear weapon effects

have been made not through deliberate scientific inquiry but by accident.

And as the following historical examples show, there has been a series of

surprises.

"Castle/Bravo" was the largest nuclear weapon ever detonated by the United

States. Before it was set off at Bikini on February 28, 1954, it was

expected to explode with an energy equivalent of about 8 million tons of

TNT. Actually, it produced almost twice that explosive power--equivalent

to 15 million tons of TNT.

If the power of the bomb was unexpected, so were the after-effects. About

6 hours after the explosion, a fine, sandy ash began to sprinkle the

Japanese fishing vessel Lucky Dragon, some 90 miles downwind of the burst

point, and Rongelap Atoll, 100 miles downwind. Though 40 to 50 miles away

from the proscribed test area, the vessel's crew and the islanders received