Hunting for a reference to an old paper by Gwin Vivian, I ran across this talk from a few years back by the ubiquitous Jared Diamond. The questions raised by Diamond are relevant to the topic I've been reading about of late, the effect of climate variability on human societies. My question is why some societies adjust to variability on a decadal scale, while others collapse

Diamond poses the question more broadly: why did some pre-industrial societies collapse under environmental stress, while others survived? Like the best questions, this one offers no easy analysis, but part of the answer seems to have to do with a society's ability to live within available resources. He uses the example of Easter Island, where people keep cutting down the trees until there were none left, then seemed to have started eating one another. This was not a fruitful coping strategy.

And what of Chaco (my favorite set piece for this discussion)?

We can now return to the question subject to longstanding debate: was Chaco Canyon abandoned because of human impact on the environment or because of drought? The answer is: it was abandoned for both reasons. Over the course of five centuries the human population of Chaco Canyon grew, their demands on the environment grew, their environmental resources declined, and people came to be living increasingly close to the margin of what the environment could support. That was the ultimate cause of abandonment. The proximate cause, the proverbial last straw that broke the camel’s back, was a drought that finally pushed Chacoans over the edge.