People commonly assume that environmental degradation and resource depletion will lead to conflict, however  ecological problems can also lead to cooperation.

Earthtrends reviews some recent research in this area in Using Environmental Negotiations Toward Peace:

Ecological resources have factored into many national conflicts–either through competition for scarce resources or greed to exploit plentiful ones. But some scholars see another role for the environment: fostering peace. Resources managed jointly can quell regional hostilities, or better, keep lines of communication open so that a conflict never starts, these scholars say, and it seems the idea is gaining traction.