Fallout ash likely to ensure extinction

Metta Spencer — May 1984

According to the most widely accepted current theory, the dinosaurs became extinct quite suddenly, as a result of a cosmic accident. Perhaps a meteor struck earth with such force that vast clouds of dust or smoke blanketed the planet and shut out the sunlight for months at a time. Perhaps it was a volcano. In any case, everything froze, and many species, including dinosaurs, became extinct.

We may be next. If so, the smoke will be of our own making; the extinction of our species will he our own doing.

During the past two years, many scientists have carefully re-examined their projections for the outcome of a nuclear war, and now claim that their previous estimates were much too optimistic. Their conclusions about radiation fallout had been based on the evidence from the Hiroshima and Nagasaki bombs, which exposed the surrounding population to far less radiation than the weapons that are ready for use in World War III. It seems likely now that the fallout in the entire northern hemisphere will average 100 rads, so that almost no one will escape radiation sickness.

Moreover, scientists had never thought much about the effects of smoke on the world’s climate. The first study on this subject was released only two years ago by the World Health Organisation. Since then it has been matched by three other independent groups of scientists a group at Cornell University; another at Boulder, Colorado; and a group of Soviet scientists. (See the report in the April issue of the Bulletin of the Atomic Scientists.)

New investigations are being planned by researchers in Canada, including one being organised at the University of Toronto’s Institute for Environmental Studies by Professor T.e. Hutchinson.

In a nutshell, the conclusions of the four completed studies are as follows. If as few as 100 megatons were exploded over 1000 cities, our species might become extinct. With larger numbers of nuclear explosions, that outcome would become more certain. Whoever starts a nuclear war will perish from it, like the rest of humanity, whether the other side retaliates or not. An attacker could perhaps “win” — but only for about two weeks.

Cities contain enormous amounts of tlammable material, including plastics and other synthetic products that release toxic fumes, such as carbon monoxide and dioxins, when burned. These would disperse throughout the atmosphere, especially in the northern hemisphere, where almost all of the bombs are targeted.

Even more disastrous will be the soot. The smoke from cities struck by 100 megatons of nuclear weapons would contain 225 million tons of carbon that would billow upward and within a few days spread out, blotting out about 95 percent of the sunlight and turning day into night.

Immediately the temperatures would drop, chilling continental areas to below minus 20 degrees Celsius. In the worst case, the cold would reach minus 40 degrees Celsius. However, Carl Sagan, one of the scientists reporting on this research, points out that there is a threshold involved: the climatic effects of 100 megatons would be almost as bad as the effects of 5000 megatons.

Only very gradually would the dust settle; it would take around four months for the daytime to resemble dusk and for the temperature to begin rising toward the normal level again. If the smoke disperses very high up in the atmosphere, the nuclear night might last a whole year.

Thirst would be another problem. Fresh water supplies would all freeze. The top layers of the ice would be the most contaminated from the fallout, so that people and animals would die of thirst or, if they managed to melt ice and drink it, poisoning.

The pollutants in the stratosphere would destroy the ozone. After the soot particles had fallen, this thinned ozone layer would admit about twice as much ultraviolet radiation from the sun as before, endangering the immune systems and genes of any organisms that had survived the disasters up to that point.

The effect in tropical regions will be more serious than those farther north; tropical plants become extinct when they all freeze. For the same reason, a summertime nuclear exchange will be more catastrophic than a winter one, since vegetation destroyed during its growing season can leave no seeds for regrowth in a subsequent year. Even if all the bombs were detonated in the north, the ecosystem of the entire planet would be in peril.

Biologist Anne Ehrlich describes the prospect of the nuclear winter vividly: “Uncountable populations of plants and animals throughout the northern hemisphere would be obliterated; their disappearances would reverberate through ecosystems as the loss of one population led to the eradication of others dependent on it. In subtropical and tropical regions, where species diversity is far richer, but where most organisms are less able to tolerate loss of, light and warmth, the cascade of extinctions could reach proportions unequalled since the dinosaurs disappeared… “

The dinosaurs had no choice, but we do.

The Peace Calendar

Canadian Disarmament Information Service, 1983-1984

Fallout ash likely to ensure extinction