BOOK REVIEW : Polemical Horrors of the Nuclear Winter : A PATH WHERE NO MAN THOUGHT: Nuclear Winter and the End of the Arms Race, by Carl Sagan and Richard Turco . Random House Inc. $18.95, cloth; 320 pages

By WILLIAM J. SCHULL

Dec. 25, 1990 12 AM PT

SPECIAL TO THE TIMES: Schull was a member of the Atomic Bomb Casualty Commission that visited Japan after World War II to study the genetic effects of radiation on A-bomb victims. His most recent book is "Song Among the Ruins" (Harvard)

While some officials in the Reagan Administration predicted that Americans could survive a nuclear war “with enough shovels” to dig for cover, the picture presented by many working scientists is far darker. In this provocative study of the dangers of nuclear proliferation, astrophysicists Carl Sagan and Richard Turco argue that smoke clouds will occlude the sun’s warming effects after a full-scale nuclear war, bringing the bone-wracking chill and darkness of an arctic winter.

The image, to be sure, is emotionally jarring, but it might not be entirely true. Scientists unrepresented in these sometimes polemical pages have argued that the evidence gathered so far--from volcanic eruptions at Mt. St. Helens to forest fires in Yellowstone--does not support the most dire predictions.

Some scientists differ only on the degree of destruction, not disputing the inevitability of a catastrophe. Other differences are more fundamentally scientific, dealing, for example, with the validity of the convection current modeling the authors use to predict effects from the area immediately adjacent to the Earth--the troposphere--up to the stratosphere.

In the final analysis, neither the authors nor their critics can muster arguments that are based on more than the imperfect art of computer modeling, whose failures at predicting weather are well-known to those who live in volatile regions such as the tropical storm belt.

Still, we cannot afford to wager if the horrendous consequences of nuclear winter are even remotely possible. A miscalculation could precipitate enormous climatic and environmental changes and ultimately kill a substantial fraction of humankind as well as the worsen of the quality of life for the minority who survived.

While not always persuasive as scientists, Sagan and Turco are effective politicians, revealing some of the duplicity that has surrounded the politics of nuclear deterrence and the senselessness of the belief that a strategy which threatens all of us nonetheless protects some of us. Also well-reasoned is their call for a nuclear strategy based on the principle of minimum sufficient deterrence.

Publication of “Path Where No Man Thought” is particularly timely in view of the brinkmanship in the Middle East into which we have been thrust. As we possibly edge toward war, can there be a more pertinent or greater recommendation to ponder carefully these authors’ arguments, lest we stumble into a situation no thoughtful person would wish? Surely an aroused public is the greatest deterrent to a nuclear winter, and this book will help inform their discretion.

Next: Jonathan Kirsch reviews “Olga” by Fernando Morais (Grove).