Regional nuclear war could devastate global environment

The two studies represent the first quantitative assessment of the consequences of a nuclear conflict between small or emerging nuclear powers, said Professor Owen "Brian" Toon with the University of Colorado-Boulder.

"Nations like Pakistan, India and North Korea, which have the potential of detonating 50 relatively small nuclear weapons, are as dangerous as the Soviet Union used to be. I think the world�s politicians need to pay closer attention to the path we all are headed down," said Toon, chair of CU-Boulder�s Atmospheric and Oceanic Sciences Department.

The crater created by India's underground nuclear test on May 11, 1998 at Pokhran in Rajasthan. © Government of India

Environmental fallout

Toon says even the smallest nuclear powers today likely have 50 or more Hiroshima-sized weapons. The world's first atom bomb used in war was dropped on Hiroshima, Japan on August 6, 1945 during World War II, killing an estimated 140,000 people. Roughly 62 million people died in World War II.

"The current buildup of nuclear weapons in a growing number of states points to scenarios in the next few decades that are even more extreme than those considered in this analysis," he said.

While a confrontation among emerging nuclear powers might be geographically constrained, the environmental impacts likely would be worldwide, the studies found.

"Considering the relatively small number and yields of the weapons, the potential devastation would be catastrophic and long term," said Toon.

The results represent the first comprehensive analysis of the consequences of a nuclear conflict between smaller nuclear states.

Pakistan test-fired the newest version of its short-range nuclear capable missile December 8, according to a military statement. The test, the third in three weeks, was part of training exercises by the Pakistan army's Strategic Force Command.

The Pakistani test came one day after the US House of Representatives approved legislation that would allow US shipments of nuclear fuel for power generation to India, Pakistan's nuclear armed neighbour.

Toon said the current combination of nuclear proliferation, political instability and urban demographics "forms perhaps the greatest danger to the stability of human society since the dawn of man."

Urban firestorms

Currently, about 40 countries possess enough plutonium, uranium or a combination of both to construct substantial nuclear arsenals, the researchers said.

Using computer tools originally developed to assess volcano-induced climate change, the researchers generated simulations depicting potential climatic conditions that a small-scale nuclear war could bring about.

The estimates are based on current nuclear weapons inventories and population densities in large urban regions and took into account scenarios of smoke emissions that urban firestorms could produce, Toon said.

The scientists modeled the effects on each country using 50 Hiroshima-sized nuclear weapons to attack the most populated urban areas of an enemy nation.

"While there is a perception that a nuclear build-down by the world�s major powers in recent decades has somehow resolved the global nuclear threat, a more accurate portrayal is that we are at a perilous crossroads," said Toon.

Toon led the studies, working with University of California-Los Angeles Professor Richard Turco, and Rutgers professors Alan Robock and Georgiy Stenchikov.

Pakistan's Shaheen-II surface-to-surface ballistic missile was test-fired on March 9, 2004. © Government of Pakistan

"Considering the relatively small number and size of the weapons, the effects are surprisingly large," said Turco, a co-author on both papers who formerly headed a research team that included Toon and Carl Sagan and which developed the original concept of "nuclear winter."

The second paper titled, Climatic Consequences of Regional Nuclear Conflicts, looks at the effects of the smoke produced in a regional war between two opposing nations in the subtropics, said lead author Robock.

No summer

A cooling of several degrees, for example, would occur over large areas of North America and Eurasia, including most of the grain-growing regions, Robock said. "Like earlier nuclear winter calculations, large climatic effects would occur in regions far removed from target areas or countries involved in the conflict."

The scientists compared the effects of regional nuclear war with the 1815 eruption of the Tambora volcano in Indonesia, the largest eruption in the past 500 years, which triggered what has become known as the "The Year Without a Summer."

The Year Without a Summer in 1816 included killing frosts and crop losses in New England as well as crop failures, food shortages and famines in Europe from wet and cold weather.

But Tambora's disruption lasted for only one year, while the new simulations show a limited nuclear conflict would be much more severe, according to the authors.

In a nuclear exchange involving 100 15-kiloton weapons, just 0.03 percent of the total explosive power of the world�s nuclear arsenal, they said the resulting smoke would cause large amounts of carbon particles to remain in the stratosphere for up to 10 years, triggering unprecedented climate change.

The two studies were first published November 22 in the online journal Atmospheric Chemistry and Physics Discussions.

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