NUCLEAR WINTER REVISITED
by Dr. Alan Phillips, October 2000
Those of us who were involved in peace activities in the 80's probably remember a good deal about nuclear winter. Those who have become involved later may have heard little about it. No scientific study has been published since 1990, and very little appears now in the peace or nuclear abolition literature. *It is still important.*
With thousands of rocket-launched weapons at "launch-on-warning", any day there could be an all-out nuclear war by accident. The fact that there are only half as many nuclear bombs as there were in the 80's makes no significant difference.
Deaths from world-wide starvation after the war would be several times the number from direct effects of the bombs, and the surviving fraction of the human race might then diminish and vanish after a few generations of hunger and disease, in a radioactive environment.
*The concept of Nuclear Winter*
Bombs directed at missile silos would burst at ground level and throw a huge amount of dust into the atmosphere, as the explosion of a volcano does. It is as much as a million tonnes from a large nuclear bomb bursting at ground level.
Bombs bursting over cities and surface installations, like factories or oil stores and refineries, would cause huge fires and fire-storms that would send huge amounts of smoke into the air.
The 1980's research showed that the dust and the smoke would block out a large fraction of the sunlight and the sun's heat from the earth's surface, so it would be dark and cold like an arctic winter. It would take months for the sunlight to get back to near normal.
The cloud of dust and smoke would circle the northern hemisphere quickly. Soon it could affect the tropics, and cold would bring absolute disaster for all crops there. Quite likely it would cross the equator and affect the southern hemisphere to a smaller degree.
While the temperature at the surface would be low, the temperature of the upper part of the troposphere (5-11 km) would rise because of sunlight absorbed by the smoke, so there would be an absolutely massive temperature inversion. That would keep many other products of combustion down at the levels people breathe, making a smog such as has never been seen before. PYROTOXINS is a word coined for all the noxious vapours that would be formed by combustion of the plastics, rubber, petroleum, and other products of civilization. It is certain that these poisons would be formed, but we do not have quantitative estimates. The amount of combustible material is enormous, and it would produce dioxins, furans, PCB's, cyanides, sulphuric and sulphurous acids, oxides of nitrogen, carbon monoxide and carbon dioxide in amounts that would make current concerns about atmospheric pollution seem utterly trivial. There would also be toxic chemicals like ammonia and chlorine from damaged storage tanks.
Another bad environmental thing that would happen is destruction of the ozone layer. The reduction in the ozone layer could be 50% - 70% over the whole northern hemisphere - very much worse than the current losses that we are properly concerned about. Nitrogen oxides are major chemical agents for this. They are formed by combination of the oxygen and nitrogen of the air in any big fire and around nuclear explosions, as they are on a smaller scale around lightning flashes. So after the smoke cleared and the sun began to shine again, there would be a large increase of UV reaching the earth's surface. This is bad for people in several ways, but don't worry about the skin cancers ? not many of the survivors would live long enough for that to matter. UV is also bad for many other living things, notably plankton, which are the bottom layer of the whole marine food chain. There would likely be enough UV to cause blindness in many animals. Humans can protect their eyes if they are aware of the danger. Animals do not know to do that, and blind animals do not survive. Blind insects do not pollinate flowers, so there is another reason why human crops and natural food supplies for animals would fail.
Altogether, nuclear winter would be an ecological disaster of the same sort of magnitude as the major extinctions of species that have occurred in the past, the most famous one being 65 million years ago at the cretaceous extinction. Of all the species living at the time, about half became extinct. The theory is that a large meteor made a great crater in the Gulf of California, putting a trillion tons of rock debris into the atmosphere. That is a thousand times as much rock as is predicted for a nuclear war, but the soot from fires blocks sunlight more effectively than rock debris. In nuclear winter there would also be radioactive contamination giving worldwide background radiation doses many times larger than has ever happened during the 3 billion years of evolution. The radiation would notably worsen things for existing species, though it might, by increasing mutations, allow quicker evolution of new species (perhaps mainly insects and grasses) that could tolerate the post-war conditions. (I should just mention that there is no way the radioactivity from a nuclear war could destroy "all life on earth". People must stop saying that. There will be plenty of evolution after a war, but it may not include us.)
*Governments did not like the idea of Nuclear Winter*
The prediction of nuclear winter was published by a group headed
by Carl Sagan in 1983. The initials of their names were T-T-A-P-S,
so the paper and their book has become known as "t-taps". It
caused some alarm in government circles in U.S.A. and NATO countries,
not so much because this further disaster would follow a nuclear war,
but because of the boost it gave to the Peace Movement.
Nuclear Winter seems to be a matter that the peace movement has largely
forgotten about, and the general public has completely forgotten
about. As far as I can find out, no new scientific study has been
published on the matter since 1990. I feel sure we ought to
be reminding the world of it. A new scientific study is surely
warranted by now. Computer modelling is a main tool in atmospheric
research, and the capacity of computers available to university
scientists and in government laboratories has increased very much
in the last 10 years; other atmospheric research has not been dormant.
The advances need to be applied. If a new study happened to
show that the aftermath of nuclear war would *not* include
severe changes in the weather and climate it would be great news
for the nuclear weapon establishments, and slightly good news for
those who are working for elimination of nuclear weapons, but we
should carry on just the same. If, as seems more likely, the
new study largely confirmed the T-TAPS results it would strengthen
our position in dialogue and provide a focus for a publicity campaign
to re-awaken the voting public to the need to eliminate nuclear
weapons, and the urgent need to de-alert them.