The Environmental Impact of a Nuclear Explosion

Now that we have had almost eight months to absorb the euphoria
surrounding our nuclear tests, let us for a moment step back and
reflect upon the ecological implications of a nuclear
explosion. Beyond the macho satisfaction of showing our ostensible
strength to the world, there are some critical choices which we will
need to make in the near future. My aim here is not to argue for or
against nuclear weapons but rather to present the facts about their
impact so we can keep our vision in perspective. What would happen to
our lives, and those of other organisms, if there was an above-ground
nuclear explosion, either incidental or accidental? Though the
probability of such an apocalyptic event is relatively small, the
impact has the potential of being so cataclysmic that it warrants
serious discussion.

When the photographs and video footage of Pakistan's nuclear tests
were released, the Pakistani public was struck by awe with the
powerful glow which illumined the mountain under which the explosions
took place. Though this was partly a photographic trick, which
highlighted the infrared (or heat) energy that the explosion
generated, it was still an austere and ominous preview of what a
nuclear explosion can do. From casual conversations with citizens
around the country soon after the tests, I gained an impression that
most Pakistanis think of nuclear weapons as just another more powerful
kind of weapon. The magnitude of even a modest nuclear explosion has
not yet surfaced to cognition in most minds.

So let us try and recount what actually happens when a nuclear bomb
explodes, such as the 13-kiloton bomb which exploded over Hiroshima in
1945. Although this was a very primitive nuclear device, it managed to
kill over 45,000 people within 24 hours of the blast and several
generations continue to languish as casualties.

Unlike conventional explosives which rely on the energy generated by
chemical combustion, nuclear weapons rely on the extreme energy which
is generated when an atomic reaction takes place in which one element
is converted into another element (for example when hydrogen is
converted to helium). The difference in the energy which is generated
is immense. For example a sphere of plutonium about the size of a
cricket ball is capable of producing an explosion equivalent to 20,000
tons of TNT. There are basically three types of nuclear bombs which
have been developed. The first kind are atomic bombs which use
fission reactions, or the splitting of atomic nuclei to generate
energy. This is the kind of bomb which was dropped by the Americans on
the Japanese cities of Hiroshima and Nagasaki in 1945. The second
variety are thermonuclear devices which use an atomic trigger and a
uranium jacket to start a fusion reaction in which lighter elements
such as hydrogen are forced to undergo a fusion reaction to combine
and form a heavier element. The energy liberated from 0.5 kg (1.1 lb)
of hydrogen-isotope fuel is equivalent to that of about 29 kilotons of
TNT, or almost three times as much as from the uranium in an atomic
bomb. The environmental impact of both these bombs would, however, be
similar though the magnitude would be greater in the case of a
thermonuclear device. The third kind of nuclear weapon is the neutron
bomb which is a modified thermonuclear device that does not have a
uranium jacket and thus reduces the chance of widespread radioactive
fallout. The neutrons generated from the thermonuclear device can,
however, generate radioactivity within a small impact radius, killing
life but without causing widespread fallout destruction to buildings
and infrastructure (the neutron bomb is thus a tactical weapon).

The greatest devastation can be caused by a nuclear device when it is
actually detonated slightly above ground rather than on the ground
itself because the expanse of the damage can be dispersed more
quickly. The detonation of a nuclear device about five hundred meters
above land would first generate an enormous fireball, whose radiant
energy would travel at the speed of light in all directions. The
intense heat generated at several thousand degrees Celsius would
incinerate all organic material within seconds. Even stable
substances such as sand would be thermally changed to glass. The
extreme temperatures would cause otherwise harmless combustion
processes to release deadly pyrotoxins that would travel as gaseous
clouds beyond ground zero. For example, a woolen suit when burned at
extreme temperatures can release enough hydrogen cyanide to kill seven
people.

The shockwave generated by the blast would travel at the speed of
sound shaking the foundations of buildings and bringing them down
within a matter of minutes. The damage radius increases with the power
of the bomb, approximately in proportion to its cube root. If exploded
at the optimum height, therefore, a 10-megaton weapon, which is 1000
times as powerful as a 10-kiloton weapon, will increase the distance
tenfold, that is, out to 17.7 km (11 mi) for severe damage and 24 km
(15 mi) for moderate damage. Meanwhile, looming over the scene would
be the proverbial mushroom cloud. Propelled by the intense pressure
differentials, the cloud would suck up debris and hurl it several
miles into the earth's atmosphere. This cloud, depending on the
intensity of the blast would blanket the area with a pall that could
last for several days, blocking out sunlight and causing severe
microclimatic changes. After the extreme heat of the blast has
dissipated, the debris cloud would block sunlight, thereby decreasing
the proximate temperature below freezing. The effect would be similar
to the global temperature decreases which occurred in 1991 when Mount
Pinatubo erupted in the Philippines. Even below ground nuclear tests
can cause severe seismic variations that can lead to earthquakes and
tremors within a thousand mile radius. Indeed, the earthquake in
Afghanistan, soon after our nuclear tests (in which over 5,000 people
were killed) may have been more than a coincidence.

The most insidious environmental damage of a nuclear explosion would,
however, result from the release of radioactive materials that would
generate intensely penetrating energy capable of causing cellular
damage for years to come. Carcinogenic (cancer-causing) and
teratogenic (initiating birth defects) effects of radiation have been
documented from the Hiroshima and Nagasaki blasts as well as the
Chernobyl nuclear reactor meltdown. In the case of Chernobyl (which
was not even a deliberate explosion), a study conducted by the Center
for Disease Control and Yale University estimated that out of the
115,000 people evacuated as a consequence of the 1986 incident, 24,000
would have a doubled risk of acquiring acute leukemia. This
discussion may seem irrelevant to many people who believe that since
we are simply developing the weapons as a deterrent, there is no point
in thinking about their actual use. What we must remember is that
there is always the chance of an accident. Indeed, there are
documented cases of accidents involving nuclear weapons tests in many
parts of the world. Several islands in the South Pacific are
uninhabitable for this very reason. Even the usually reticent US
Defense Nuclear Agency has stated that "accidents have
occurred...which released radioactive contamination because of fire or
high explosive detonations".

It is very true that the West has no moral authority to dictate terms
of disarmament to us when their own record is so dismal. However, like
other instances of colonial emulation, must we also follow in their
footsteps when it comes to something as supremely consequential as
nuclear weapons?