I don't know how Sam Andreas can say anyone be truly ready for nuclear war especially since most, if not close to all, living animals and plant species would quickly or gradually become extinct. The air, water, streams and rivers and oceans would become increasingly toxic and so radioactive, a human extinction event would be a real, actual exiatential possibility..
But, hey don't just take my word for it. The late Carl Sagan narrated an excellent PBS "what-if" documentary during the early 80's geopoliitical, re-heating of the Cold War about the dangers, perils facing remaining human beings living in a post-apocalytpic nuclear fallout landscape with colr, radioactive "nuclear winters", scant vegetation, animal life---the prognosis wasnt optimistic. In fact, the predictions and descriptions seemed almost hellish and I know you're not religious, but it would probably resemble Hell on Earth. Or the closest, natural equivalent to it and like Hell itself, these climatic changes would be permanent.