By Raloff, Janet
Science News , Vol. 128
Even if as many as 1 billion people in the Northern Hemisphere were killed outright as a result of a massive nuclear exchange between warring superpowers, four times that number would probably survive globally, according to Mark Harwell, associate director of the Ecosytems Research Center at Cornell University in Ithaca, N.Y. And what awaits those survivors can be predicted only by analyzing how natural ecosystems and agriculture would respond to nuclear-war-initiated stresses.
Indirect effects of a strategic nuclear war are likely to be far more consequential, killing far more people, than would be the direct effects of nuclear salvos lobbed between combatants, says Harwell. He believes the significance of these indirect effects has been widely overlooked until now because earlier analyses have largely ignored the far-ranging biological implications of nuclear war.
In June 1982, the Scientific Committee on Problems of the Environment (SCOPE) concluded that "the risk of nuclear warfare overshadows all other hazards to humanity and its habitat." Three months later, SCOPE's parent organization, the Paris-based International Council of Scientific Unions (of which the U.S. National Academy of Sciences is a member), asked its board to investigate these effects. It also commissioned "an unemotional, nonpolitical, authoritative and readily understandable statement of the effects of nuclear war -- even a limited one -- on human beings and on other parts of the biosphere."
At the sixth SCOPE general assembly, convened this week in Washington, D.C., that report was unveiled. Volume 1 deals with physical and atmospheric effects. Volume 2 covers biological effects and was prepared by Harwell with Thomas Hutchinson of the University of Toronto's Institute for Environmental Studies. What emerges, particularly from Volume 2, is a new perspective on the fragility of the agricultural systems that feed our planet.
"We've placed particular emphasis on agricultural systems because they're both the most sensitive and the most important to humans," Harwell explains. The consensus of the 200 or so biologists who contributed to the SCOPE study in 11 regional workshops over the past two years is that, even in the best of times, natural ecosystems could never feed earth's roughly 5 billion people. They're just not efficient enough. But through subsidies of energy and fertilizers, and by providing protected -- some would say artificial -- environments, agriculture has expanded the human-carrying capacity of the planet. "Indeed," the SCOPE study says, "without any agricultural productivity, at least 90 percent to 99 perent of the current human population could not be maintained indefinitely."
Yet the predicted combination of acute and chronic climatic disruptions that could be initiated by even a 5,000-megaton nuclear exchange directed at cities and high-value military targets (like missile silos) suggests, according to SCOPE, "at least the possibility of little or no agricultural productivity on up to a hemispheric scale" in the first year after a nuclear war. Moreover, the report notes that a "severe reduction in agricultural productivity" could extend into succeeding years -- even if dramatic, adverse climatic effects did not.
As a result, the report says, starvation may be the single greatest cause of death following a nuclear war.
Previous analyses of nuclear war's implications for agriculture have tended to focus on the dramatic cooling -- the so-called "nuclear winter" -- that could ocur in the northern mitlatitudes, where fighting would most likely be concentrated (SN: 11/12/83, p. 314). For example, the TTAPS study authored by Cornell astronomer Carl Sagan and his colleagues suggested that temperatures could plummet almost 35[deg.]C within just a few months of the closing salvos in a 5,000-megaton strategic nuclear battle. What the new SCOPE analysis graphically portrays is that such massive temperature drops are not necessary to wipe out agriculture for a year in the northern midlatitudes. …