Carl Sagan and other Cold War scientists once feared that a nuclear war could plunge the world into a deadly ice age. Three decades later, does this theory still resonate?

But even with the cold war and super powers no long saber-rattling against one another, none of us should be fooled into think that North Korea using a nuclear device against South Korea, or Pakistan and India exchanging lobbing nuclear bombs at one another would not have a dramatic impact on climates the world over.