From a scientific perspective there is some indication that a nuclear war could deplete the earth's ozone layer or, less likely, could bring on a new Ice Age - but there is no suggestion that either the created order or mankind would be destroyed in the process.
“And I realized, when I'd come in to the meetings with these corrugated metal and chain link stuff, and people would just look at me like I'd just landed from Mars. But I couldn't do anything else. That was my response to the people and the time.”