NEW YORK: A brief nuclear war between India and Pakistan would rip apart the ozone layer and unleash global devastation - killing millions, besides triggering catastrophic health problems, according to a study by US scientists.
Using sophisticated computer modelling, University of Colorado scientists Micahel Mills and Owen Brian Toon have showed that a nuclear war between the two South Asian neighbours, involving 100 Hiroshima-sized nuclear devices, would ignite urban fires and blast five million tonnes of soot 80 km into the air.
The soot would absorb enough solar radiation to heat surrounding gases, setting in motion a series of chemical reactions that would break down the stratospheric ozone layer, which protects the earth from harmful ultraviolet radiation.
"The scenario of a war between India and Pakistan was used as a representative of regional nuclear conflict, potential for which remains high with the increase in nuclear arsenal and the number of nuclear armed nations," Mills, who led the study published Monday in the Proceedings of the National Academy of Sciences in the US, told IANS.
Mills is a research associate with the Laboratory for Atmospheric and Space Physics at the Boulder-based university's Department of Atmospheric and Oceanic Sciences. Toon is the director of the department.
India and Pakistan are known to possess the smallest arsenals of the eight nuclear-armed powers. India has about 60 nuclear devices and Pakistan under 50. A nuclear exchange involving a hundred 15 kiloton, Hiroshima-type weapons is only 0.03 percent of the total explosive power of the world's nuclear arsenal, Toon said.
Mills said their research found that the catastrophic impact from even a small nuclear conflict would be much larger than estimated earlier from a bigger nuclear war, when simulation was not that sophisticated. The indirect human casualties elsewhere in the world would be many times more than those who actually die from the war.
"We would see a dramatic drop in ozone levels that would persist for many years," he said. "At mid-latitudes the ozone decrease would be up to 40 percent, which could have huge effects on human health and on terrestrial, aquatic and marine ecosystems."
The upper stratosphere, heated by massive smoke injections, would accelerate catalytic reaction cycles, particularly reactions of nitrogen oxide gases that destroy ozone.
"By adopting the Montreal Protocol in 1987, society demonstrated it was unwilling to tolerate a small percentage of ozone loss because of serious health risks," said Toon.
"But ozone loss from a limited nuclear exchange would be more than an order of magnitude larger than ozone loss from the release of gases like CFCs."
The ozone losses predicted in the study are much larger than losses estimated in previous "nuclear winter" and "ultraviolet spring" scenario calculations following nuclear conflicts.
A 1985 National Research Council Report in the US predicted a global nuclear exchange involving thousands of megatons of explosions, rather than the 1.5 megatons assumed in the Mills-Toon study, would deplete only 17 percent of the Northern Hemisphere's stratospheric ozone, which would recover by half in three years.
But the new study said ailments like cataracts and skin cancer, as well as damage to plants, animals and ecosystems at mid-latitudes would likely rise sharply as ozone levels decreased and allowed more harmful UV light to reach earth.
Mills said the next step for researchers would be to study the biological impact of the nuclear war scenario, which will damage all organisms, on land and on ocean, thus polluting the food chain.
