Co-operation and Unilateral Commitment inthe Presence of Global EnvironmentalProblems

This paper focuses on the link between group co-operation and unilateral commitment of some countries in the presence of global environmental problems. We show that in case of a failure of negotiation, some countries can decide to commit unilaterally and reduce their emissions. we call this behaviour precautionary commitment.Absence of international agreement does not mean global defection from the environmental issue. we also show that the emergence of a non-co-ordinated global co-operation can result from a strategic actionfrom the members of the coalition. The insiders of the coalition create an incentive for the non-members to reduce without co-ordinating their emissions.