Global governance institutions for climate change, such as those established by the UNFCCC and the Kyoto Protocol, have so far failed to make a significant impact on greenhouse gas emissions. Following the lead of Elinor Ostrom, this paper offers an alternative theoretical framework for reconstructing global climate policy in accordance with the polycentric approach to governance pioneered in the early 1960s by Vincent Ostrom, Charles Tiebout, and RobertWarren. Instead of a thoroughly top-down global regime, in which lower levels of government simply carry out the mandates of international negotiators, a polycentric approach provides for greater experimentation, learning, and cross-influence among different levels and units of government, which are both independent and interdependent. After exploring several of the design flaws of the existing set of global institutions and organizations for greenhouse gas mitigation, the paper explores how those global institutions and organizations might be improved by learning from various innovative policies instituted by local, state, and regional governments. The paper argues that any successful governance system for stabilizing the global climate must function as part of a larger, polycentric set of nested institutions and organizations at various governmental levels.