We introduce uncertainty and risk aversion to the study of international environmental agreements. We consider a simple model with identical agents and linear payoffs. We show that a stable treaty with positive action always exists. While uncertainty lowers the actions of signatories, we find...

We design and implement lab experiments, as close as possible to the Ellsberg two-color urn experiment, to evaluate the positive and normative appeal of behavior arising from models of ambiguity-averse preferences. We report three main empirical findings: First, these preference models do not...