The spread of nuclear weapons to unstable third world countries such as Iraq means that despite the dramatic improvement in US/Soviet relations, we are living in a time of unprecedented danger of nuclear war.In 1990, there are still enough nuclear weapons in the world to devastate every city 25 times over. In 1982, Professors Sagan and Turco made known their discovery of the concept "nuclear winter", a widespread cold and dark, resulting in agricultural collapse and world famine, that would be generated in even a "small" nuclear war. It was a landmark discovery that revealed in the starkest terms how vulnerable our civilization is to the long-term environmental effects of nuclear war.Carl Sagan, Pulitzer prize-winning science writer, and Richard Turco, tell the personal story of their findings, and how, despite the much-heralded thawing of the Cold War, there are dangerous inadequacies in nuclear policy and doctrine that need to be addressed.