Even limited nuclear war would have global effects, CU prof says
Study: Regional conflict could kill 20 million, cripple global agriculture
By Jim Erickson, Rocky Mountain News
December 12, 2006
Even a small-scale regional nuclear war could kill more than 20 million people, cripple agriculture worldwide and alter the climate for a decade, a University of Colorado researcher and his colleagues reported Monday.
CU Professor Owen "Brian" Toon was one of the five authors of a landmark 1983 study that coined the term "nuclear winter" and examined the devastating environmental consequences expected from a full-scale nuclear exchange between the U.S. and what was then the Soviet Union.
Now, Toon and several colleagues, armed with the latest computerized climate models, have turned their attention to the effects of smaller-scale conflicts between emerging nuclear powers - the type of events considered more likely today.
They calculated the results a regional war in which two countries each lob 50 relatively small, Hiroshima-size nuclear weapons into the enemy's major urban centers.
Such an exchange would not result in nuclear winter. But the casualties and consequences would be staggering.
The researchers concluded that a nuclear exchange between India and Pakistan could kill 21.6 million people.
An attack on the U.S. with 50 Hiroshima-size bombs could kill 4 million people in this country alone.
"In the United States, France and Britain, the use of just a few weapons would create more fatalities than occurred in those countries during World War II," said Toon, chairman of CU's atmospheric and oceanic sciences department.
The study's fatality results were surprisingly high, Toon said. One explanation for the alarming numbers is the recent growth of megacities - urban centers with more than 10 million inhabitants - that could be targeted to maximize deaths.
"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," Toon said Monday during a news briefing at the annual meeting of the American Geophysical Union in San Francisco.
The researchers produced two studies that were published recently in the online journal Atmospheric Chemistry and Physics Discussions. Toon described them as the first comprehensive assessments of the effects of regional nuclear war.
Steve Ghan, a federal researcher who has studied the aftermath of nuclear war, said that the team's findings push the edges of plausibility.
"For example, they make an assumption about how much smoke would be injected into the atmosphere that is on the high side of the plausible range," said Ghan, who works at the Pacific Northwest National Laboratory in Richland, Wash. "They chose assumptions that would produce a large effect."
Toon and his colleagues concluded that the nuclear blasts would trigger firestorms emitting more than 5 million metric tons of soot. Climate models showed that a large fraction of the soot would linger in the upper atmosphere for up to a decade - far longer than researchers had previously thought possible, according to co-author Alan Robock of Rutgers University.
The soot would block sunlight,cooling the global average temperature by 2.25 degrees Fahrenheit, an immediate drop that would persist for years. The cooling would shorten growing seasons by up to a month and threaten grain-growing regions in America and Eurasia.
"This would not be nuclear winter, but it would be a substantial disruption," Robock said Monday.
In addition to the cooling, global precipitation levels would plummet and heating of the upper atmosphere would erode the protective ozone layer.
The original 1983 nuclear winter study was written by Toon, Richard Turco, Thomas Ackerman, James Pollack and Carl Sagan. Some scientists disputed the report, which claimed that darkness and cold temperatures could destroy much of the Earth's plant and animal life.
Since that report was published, the number of deployed nuclear weapons has declined worldwide by a factor of three, Toon said. But 40 countries now have fissionable material and could quickly join the nuclear club, he said.
Even limited nuclear war would have global effects, CU prof says
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