Civilization itself begins with farming. But in Gilgamesh, a divine flood provides the apocalypse. As much as anything else, it was cutting down all the trees that led the real Sumer to collapse; apparently massive clearcuts play havoc with the hydrological cycle.

And then in the depths of a decades long drought, a disastrous war. I can think of half a dozen civilizations that collapsed in large part because they either destroyed their land base or were unable to adapt to changes in hydrological cycles.

Does any of this sound familiar?