Scholars have undertaken much conceptual development of “polycentric” climate governance (PCG). Yet, there has been limited empirical examination of whether this descriptive, analytical, and normative concept can aid climate change mitigation; it may even undermine our efforts in certain contexts. Thus this special issue examines the empirical realities of PCG. Building from a shared definition of the concept, the constitutive articles analyze an exploratory range of systems, across policy styles, governance levels, and types of actors. Here we consolidate the findings of the articles by identifying five key themes that are drawn from across the special issue, for consideration in future research. These themes are operationalization of PCG systems; voluntary action; temporality; power; and, crucially, effectiveness in mitigating climate change. Our findings provide evidence from a wide range of contexts, from which we build to propose new research streams on this topic.

In recent years, climate governance has shifted from the global, multilateral regime to voluntary initiatives from multiple directions. Scholars frequently use a polycentric governance lens to study the complex and multijurisdictional reality. The polycentric perspective helps to grasp the new reality at a general level, but it is lacking in specificity. To fill this research gap, this article attempts to enhance the analytical power of the polycentric governance perspective by exploring four issues: the role of the state, diffusion of local action, integration of local democratic preferences, and the role of power. These issues are discussed by doing a systematic literature review of empirical polycentric governance literature regarding climate change mitigation. The results show the importance of states at the national level and provide insights into how local initiatives share and transfer knowledge, get supported by transnational networks, and secure compliance with local democratic preferences. The literature provides less insight into the role of power. The article concludes by developing research agendas for further cumulation of knowledge and to strengthen climate action at all levels.

The European Union (EU) has sought to lead the world in the adoption of ambitious climate change mitigation targets and policies. In an attempt to characterize and broadly explain the resulting pattern of EU climate governance, scholars have employed the term “multi-level reinforcement.” This term does help to account for the paradoxical situation whereby the EU seeks to lead by example but is itself a relatively leaderless system of governance. Drawing on a much fuller empirical account of the evolution of EU climate governance, this article finds that the term captures some but not all aspects of the EU's approach. It identifies four other paradoxical features of the EU's approach and assesses the extent to which they exhibit “multi-level reinforcement.” It concludes by looking forward and examining the extent to which all five features are expected to enable and/or constrain the EU's ability to maintain a leading position in climate governance.