The idea that a full-scale exchange of nuclear weapons between the US and the old USSR was going to end life on earth was always absurd. The boogieman, "nuclear winter" is also bullshit. We can fight a full nuclear war and walk away from it, to fight another one in the future. Yes, the major cities would suffer major damage and millions would die. But look at how fast the Japanese rebuilt and reinhabited Nagasaki and Hiroshima. Look at how quickly wildlife returned to the area around Chernobyl, and it is thriving. Yes, the nukes would throw some dust into the upper atmosphere, but the power of hydrogen bombs pales in comparison with the power of a major volcanic eruption.