I just recently finished reading a very depressing book, "A Short History of Progress", which is essentially an account of the many, many historical examples of human civilisations which degraded and over-exploited their environments to the point where they could no longer support their populations. Chilling stuff, especially in light of the current global warming crisis. All in all, I'd definitely recommend the book; it's an excellent reminder that civilisation has always been a rather precarious business and that Malthus hasn't necessarily been proved wrong yet.