Whereas the US President signed the Kyoto Protocol, the failure of the US Congress to ratify it seriously hampered subsequent international climate cooperation. This recent US trend, of signing environmental treaties but failing to ratify them, could thwart attempts to come to a future climate...

Using a repeated-game model, we demonstrate that by limiting the punishment for non-compliance, a climate agreement with full participation can be sustained as a weakly renegotiation-proof equilibrium even without watering down abatement levels.