The Economist has an interesting article on the implications of global warming for Africa (sub. req.). Particularly interesting is this image:
The next step is to map which of the countries that are in the shaded region have the most other stressed systems (political, economic, military, agricultural, etc.) and you begin to get a good sense of where things are going to get really bad.
And here's the key point: the ecological/climate crisis is going to appear in the headlines as a crisis of political economy in these regions. Thus the climate crisis in Darfur may appear as a "genocide." Thus the climate crisis in Nigeria may appear as an uprising of a new breed of global guerrillas. Thus the climate crisis in Zimbabwe may appear as the sociopathic derangement of a superannuated leader.