There is no integrated, comprehensive regime governing efforts to limit the extent of climate change. Instead, there is a regime complex: a loosely coupled set of specific regimes. We describe the regime complex for climate change and seek to explain it, using functional, strategic, and organizational arguments. It is likely that such a regime complex will persist: efforts to build an effective, legitimate, and adaptable comprehensive regime are unlikely to succeed. Building on this analysis, we argue that a climate change regime complex, if it meets specified criteria, has advantages over any politically feasible comprehensive regime, particularly with respect to adaptability and flexibility. These characteristics are particularly important in an environment of high uncertainty, such as in the case of climate change where the most demanding international commitments are interdependent yet governments vary widely in their interest and ability to implement such commitments.