This lecture discusses the importance of international coordination in climate change mitigation due to the shared global budget nature of climate protection. It explores the challenges of free riders, the prisoner's dilemma, and conditions for solidarity in climate efforts. The lecture also covers effort allocation criteria based on exposure to climate impacts, economic capacity, historical emissions, and equal emissions per capita. Emissions by different regions and the main difficulties in decision-making, ethics, monitoring, and fund transfers are analyzed. The conclusion highlights the necessity of voluntary coordination among countries for effective international environmental treaties.