Brush blazes help test `nuclear winter' theory

An experiment to study whether smoke and dust from atomic war would trigger a ``nuclear winter'' was delayed by a helicopter crash. After a helicopter had dumped flaming gasoline on dead brush to ignite a five-acre test burn Wednesday, the cable suspending the torch from the craft snagged on utility lines, causing it to crash.

The large blaze initially had been planned to reduce the wildfire hazard by clearing dead brush, but attracted Pentagon-funded scientists and others who are interested in studying how smoke from an atomic war might blot out sunlight to plunge Earth into a dark, chilly nuclear winter.

Army Lt. Col. Carlton Brown, spokesman for the Defense Nuclear Agency, said his agency was spending $2.5 million annually for studies of this theory, first proposed in 1983 by atmospheric scientist Richard Turco, astronomer Carl Sagan, and other researchers.

Such data could be used by computers to predict what might happen after atomic war, but probably wouldn't settle debate over whether such a war would cause a subfreezing nuclear winter or a milder nuclear autumn.

From this experiment, other scientists hope to learn more about air pollution, acid rain, erosion, and mudslides, threats to Earth's ozone layer and how wildfire gases contribute to the greenhouse effect, in which certain gases trap the sun's heat to warm the atmosphere.

Several hundred scientists gathered at Los Angeles National Forest's San Dimas Experimental Forest 30 miles northeast of Los Angeles to watch the $750,000 experiment.