Copley News Service June 10, 2002 Monday
Fallout from nuclear war in South Asia seen as unlikely to reach U.S.
By: Bruce Lieberman Copley News Service
The horror of a nuclear war between India and Pakistan could decimate South Asia's largest cities, killing up to 12 million people and bringing misery to countless others.
But a war, if limited to those two nations and the nuclear arsenals they are thought to possess, poses little danger of radioactive fallout reaching North America, physicists and atmospheric scientists say.
There are fundamental reasons.
First, India and Pakistan are believed armed with less potent weapons, probably no larger than the equivalent of 15,000 tons of TNT, about the same size as the bombs the United States dropped on Hiroshima and Nagasaki in 1945. In contrast, the typical nuclear weapon in the U.S. stockpile today is 10 to 20 times more powerful than the weapons held by India and Pakistan, according to GlobalSecurity.org.
Second, the two countries are thought to have no more than 200 warheads between them - not enough, scientists believe, to endanger populations far beyond South Asia.
More than 31,000 nuclear weapons, by contrast, are maintained by eight known nuclear powers, and 95 percent are in the United States and Russia, according to the Bulletin of Atomic Scientists, which monitors nuclear proliferation.
Third, the approaching summer in the Northern Hemisphere will mean an absence of fast-moving winter storms that could carry nuclear fallout quickly across the globe. Further, South Asia's monsoon season, which begins this month and extends into October, could wash nuclear fallout back to Earth, confining the worst environmental damage to that part of the world.
"Of course, there will be some radiation reaching globally, but the amounts will be small compared to the levels that would produce health effects," said Charles Shapiro, a physicist at San Francisco State University, who co-authored a 1985 study on the environmental effects of nuclear war.
Irradiated particles blasted into the atmosphere from a nuclear war between India and Pakistan, carried aloft by the jet stream, would eventually reach every part of the globe and rain back down to Earth as fallout, scientists say.
Atmospheric studies conducted by scientists at the Scripps Institution of Oceanography in La Jolla, Calif., have found that particulate from pollution in South Asia can reach the West Coast of the United States in as few as six days.
However, those studies focused on the migration of haze in South Asia that covers thousands of square kilometers - a much greater area than that affected by a nuclear explosion, said V. Ramanathan, an atmospheric scientist at Scripps.
"It's very risky to extrapolate" data from the pollution study, he said.
Ramanathan's study found that particulates larger than 10 microns in diameter fell to Earth before reaching North America, so it's unclear how much radioactive fallout might reach the West Coast, or how dispersed it would be, he said.
"I think East Asia has more to worry about, as well as Europe," Ramanathan said.
Larry Riddle, a climatologist at Scripps, said the levels of radiation reaching the United States probably would not be any higher than background radiation.
Humans are exposed every day to radiation from space, from deep in the Earth, and from man-made sources such as medical X-rays and other consumer products.
"Essentially, it would have no effect," Riddle said.
How much radiation might disperse around the globe depends on several factors, scientists say.
An atomic bomb detonated above ground creates a large fireball but very little fallout because it does not hit the ground and blast irradiated particles and other debris into the air.
A bomb that explodes on the ground or near the ground, however, would gouge a massive crater and hurl dust and debris high into the atmosphere. Airborne particles irradiated by the blast would rain down to Earth as fallout over a wide area.
Radioactive debris rising no more than about 50,000 feet, the upper reaches of the troposphere, would return to Earth much more rapidly than if it rises into the stratosphere, above that altitude.
"Fallout from a weapon ... decays extremely rapidly, so if it comes down to Earth quickly, it's much more potent and potentially damaging than if it stays up for a long while," Shapiro said.
Nuclear bombs detonated by India or Pakistan, if they are the size of the bomb the United States dropped on Hiroshima, might send a mushroom cloud 20,000 feet into the atmosphere.
In that case, South Asia's torrential monsoon season could make a horrific situation worse for those who live there.
In the 2001 book "Out of the Nuclear Shadow," a group of physicists and environmental experts speculated about the results of a single Hiroshima-sized nuclear bomb detonated nearly 2,000 feet over Bombay, India.
They gave the following scenario, based on the damage documented at Hiroshima and current conditions in Bombay:
The initial blast, brighter than 1,000 suns and suffused with intense nuclear radiation, would set fire to everything combustible for one to two miles around ground zero.
The blast would be followed by a shock wave creating winds 70 miles per hour or more, destroying everything within a radius of nearly a mile. Many of the buildings in Bombay, made from raw materials and poorly constructed, would not survive.
Firestorms, covering up to 1.2 miles from ground zero, would create winds 30 to 50 miles per hour. Temperatures in the fire zone, fueled by liquid gas cylinders in many Bombay homes and a high concentration of cars, scooters and buses, would reach several hundred degrees.
Radioactive fallout, intensified by Bombay's high humidity, probably would be fatal for 15 to 62 square miles around ground zero.
In all, nearly 478,000 people in Bombay would be killed after a single nuclear explosion, and an additional 229,000 would be severely injured, the authors estimated.
The U.S. Defense Department based its estimate of 12 million dead in an India-Pakistan nuclear war from the most recent assessments of the nuclear capabilities of both countries.
Casualty estimates from a total nuclear exchange between the two countries would depend on where the bombs fell, the weather conditions and many other factors.
The inability to treat burn victims, the onset of infectious disease, the lack of water and food - all would amount to a catastrophe probably never seen before, said experts with the Washington, D.C., group Physicians for Social Responsibility.
"Any kind of medical response is totally out of the question," said Roy Farrell, the group's president. "We're just talking about survival."
San Diego Union-Tribune staff Writer Michael Stetz contributed to this report.
Copyright 2002 Copley News Service
