I agree that 2 --> 3 --> 4 is tenuous but I think 1 --> 2 is very well-established. The climate-conflict literature is pretty definitive that increases in temperature lead to increases in conflict (see Burke, Hsiang and Miguel 2015) and not just at the small scale. Even under Blattman’s theory, climate --> conflict doesn’t rely on decisionmakers becoming more irrational or uncooperative in any way. It simply relies on them being unable to overcome the tension of resource scarcity with their existing level of cooperation/rationality. A fragile peace bargain can be tipped by shortages, even if it would otherwise have succeeded.
I agree that 2 --> 3 --> 4 is tenuous but I think 1 --> 2 is very well-established. The climate-conflict literature is pretty definitive that increases in temperature lead to increases in conflict (see Burke, Hsiang and Miguel 2015) and not just at the small scale. Even under Blattman’s theory, climate --> conflict doesn’t rely on decisionmakers becoming more irrational or uncooperative in any way. It simply relies on them being unable to overcome the tension of resource scarcity with their existing level of cooperation/rationality. A fragile peace bargain can be tipped by shortages, even if it would otherwise have succeeded.