The decline of the Soviet Union may have left many Americans feeling safer from nuclear war, but a disturbing new study argues that an attack by terrorists sponsored by a small nuclear state could be just as lethal.
Such an attack "could generate casualties comparable to those once predicted for a full-scale nuclear exchange in a superpower conflict," says the report, presented Monday during the fall meeting of the American Geophysical Union in San Francisco.
Furthermore, Americans should not think of themselves as isolated from potential small-scale, regional nuclear conflicts in such distant areas as the Middle East or Asia. The impact of such an encounter would be global, probably plunging the planet into a "nuclear winter" and blanketing wide areas of the world with radioactive fallout.
The report, which cautions that there are many uncertainties in its own conclusions, was produced by a team of scientists who have been long active in studying the consequences of nuclear war.
The study assumes that weapons used by terrorists, or smaller states, would be much smaller than those available to the superpowers, probably on the scale of those dropped on Japan during World War II. But the results would be catastrophic because the weapons would most likely be targeted at major cities.
"The current combination of nuclear proliferation, political instability, and urban demographics forms perhaps the greatest danger to the stability of society since the dawn of humanity," Brian Toon of the University of Colorado in Boulder told a press conference prior to the presentation.
The number of countries known to have nuclear weapons has grown to eight, but as many as 40 have some fissionable material and could produce bombs fairly quickly, the scientists said, basing their conclusions partly on studies by the National Academy of Sciences, the Department of Defense, and their own years-long research. Toon said Japan, for example, has enough nuclear material on hand to produce 20,000 weapons, and "most think they could do it in weeks."
Many of the conclusions are based on the consequences of two nations, each with 50 bombs, delivering their full complement of weapons on each other. That's not a hypothetical figure, they suggested, because both India and Pakistan are believed to have at least that many weapons.
So what would happen if they had at it?
About 20 million persons in that area would die, the scientists concluded. But the weapons would send up such a plume of smoke that the upper atmosphere would become opaque, blocking out so much solar radiation that temperatures around the world would plummet.
"You would have a global climate change unprecedented in human history," said Alan Robock, associated director of the Center for Environmental Prediction at Rutgers Cook College and a member of the research team. "It would instantaneously be colder than the little ice age." There would be shorter growing seasons, less rain, less sun, and starvation around the world.
Richard Turco, the founding director of the Institute of the Environment at the University of California, Los Angeles, said the results would be about 10 times worse than the historic eruption of Tambora in Indonesia in 1815, which sent killing frosts across North America. That year became known as "the year without a summer."
The scientists concede there are "many uncertainties" in their findings, partly because it's impossible to predict just who is likely to go to war with whom, and how those wars will be fought. But they point out, as astronomer Carl Sagan did years ago, that during World War II the United States had only two nuclear bombs, and it dropped both of them on Japanese cities. So it's not unprecedented that other countries would also likely attack major cities.
And that's one reason the scientists are so alarmed. Urbanization has swept the planet, and today there are many cities with more than 10 million inhabitants, many of them in areas where the political climate is unstable and hostile. Even one nuclear weapon, they concluded, could kill more people than some countries have lost through war during their entire history.
That lead Turco to conclude that "human society is extremely vulnerable at this time," a modest statement considering these conclusions in the report:
"Thirty-two countries that do not now have nuclear weapons possess sufficient fissionable nuclear materials to construct weapons, some in a relatively short period of time."
In some cases, the casualties could "rival previous estimates for a limited strategic war between the superpowers involving thousands of weapons carrying several thousand megatons of yield," partly because more people live in concentrated areas, surrounded by more and more volatile materials.
"An individual in possession of one of the thousands of existing lightweight nuclear weapons could kill or injure a million people in a terrorist attack."
"Many nuclear weapons are small in size and light in weight and could easily be transported in a car or van." Some tactical nuclear weapons in the U.S. arsenal, for example, weigh only about 300 pounds.
The scientists admit that the lethality of a weapon is subject to many variables, even such things as local wind and whether it's raining, so their numbers should not be taken as absolutes.
But they insist that while many Americans may think the world is growing safer and the nuclear threat is easing, the opposite is true.
"We're on a trend toward a buildup (in nuclear weapons) around the world," Toon said.
And it wouldn't take a huge arsenal, or many weapons, to produce catastrophe. "Even a single surface nuclear explosion, or an air burst in rainy conditions, in a city center is likely to cause the entire metropolitan area to be abandoned at least for decades owing to infrastructure damage and radioactive contamination," the scientists say in the conclusion of their report. It would also leave at least a million dead, and a million more injured.
The danger from nuclear weapons is not less today than when two superpowers threatened each other just a few years ago. It is more, they said repeatedly. Much more.