The thing that really fascinated me about the book was the unseen and unspecified catastrophe that had led to the horrible environment that the father and son found themselves in.

When I've spoken to other people, who've read the book, I've always asked them, "what do you think caused the disaster?" And everyone has said 'nuclear war'. But looking at the characteristics of the disaster described therein, it occurred to me that it might be something much more terrifying and outside of human control. I'm also left wondering if that is the real point of the book? We do all seem to be attached to the idea that the fate of the planet is in our hands, don't we? If you know anything about geological history, this is absurd!