<p>Participation in climate agreements significantly shapes their overall effectiveness. This study aims to apply Ostrom’s Common Pool Resources (CPR) and polycentric governance (PG) frameworks to analyse tensions over participation and cooperation among state and non-state actors within the international climate regime. It explores equity, the interplay between local and global decision-making, and the role of incentives, highlighting the complexities of fostering broad and accountable participation in climate agreements. Compared to a fully decentralized system, this research demonstrates that a balanced combination of centralized and decentralized approaches is crucial for fostering effective participation and cooperation within the complex landscape of the international climate regime. In addition, sanctions play a vital role in polycentric systems, as highlighted by Ostrom’s principles; however, their absence within the international climate regime reflects an inherent tension between the need for global cooperation and the principle of national sovereignty, and poses significant challenges to the effective cooperation and participation.</p>