Time Magazine: In the 1980s, climate scientists in Russia and the U.S. theorized that all-out nuclear war between the superpowers would result in a “nuclear winter,” as smoke from the atomic explosions blackened the sky and sent summer temperatures plummeting below freezing – killing crops and eventually starving all those who survived the initial explosions. Now that the risks of an all-out U.S.-Russian exchange have diminished, scientists are looking at the climactic effects of regional nuclear war – and …