There's a fascinating, informative discussion thread on the dynamics of societal collapse over at The Oil Drum, prompted by a very readable 10,000 word essay on the fall of the Roman empire, cleverly entitled, "Peak Civilization." This is really complicated stuff that the news media utterly fails to convey, preferring instead to focus on single-cause "forcings," be it drought, climate change, overpopulation, or overexploitation of natural resources. I'm susceptible to this myself with respect to drought. Of course, the media takes its cue from scholars such as Jared Diamond, whose one-size-fits all thesis is pretty well deconstructed by Joseph Tainter. Fans of Tainter will be heartened to know that his work is intelligently discussed (as far as I can tell) at the aforementioned essay and comment thread on The Oil Drum.