The C40 city-network claims a position of global leadership in the governance of climate change. This chapter provides a brief overview of the history of the network, its member cities, and their collective aims and objectives. The chapter introduces the empirical puzzle around which the book is organized, namely the ability of the C40 to achieve coordinated action from a diverse collection of cities despite relying on voluntary participation and engagement. The ability to do so sets the C40 apart from other similar city-networks and begs the question as to how it has been able to achieve coordination and collective effort. The chapter asserts that such voluntary coordination is only possible through the formation of a collective identity and draws on ideas from the scholarship on social fields, social constructivism, and social movements to develop a theory of global urban governance fields that explains when, how, and why the C40 has managed to generate convergence around a set of governance norms and a shared governance identity.

The C40 has made assertive claims with respect to its ability to engender increased engagement, ambition, and scope of climate governance over both time and space. This chapter provides an independent corroboration of these claims, which have to-date been based on internal network data and analysis, by drawing on a novel dataset of over 10,000 climate governance actions adopted by C40 cities between 2001 and 2018. The chapter confirms that the C40 has increased the level of member city engagement, action, and ambition across geographic and economic divides. This renders the C40 distinct from other voluntary city-networks such as ICLEI and is deeply puzzling given the inability of these networks to deploy coercion or hard compliance mechanisms to close the gap between nominal commitments and concrete actions. The chapter concludes by considering three alternative explanations: as a function of economic development; as a function of inter-city learning, and as a function of the efforts of the network bureaucracy. Each is shown to be incomplete, thus demonstrating the need for a novel means of theorizing coordination in city-networks like the C40.

Whereas the C40 was fragmented in its early years, the network underwent a process of transformative change that began with the selection of Michael Bloomberg, as mayor of New York City, as C40 Chair in late 2009. As described in Chapters 1 and 3, both coordination and convergence around a common set of governance norms and a collective identity were increasingly apparent during the four-year period (2010-2014) in which New York occupied the C40 Chair. The theory of global urban governance fields is applied to explain why Bloomberg and New York were able to achieve what both the Clinton Climate Initiative and previous C40 Chairs could not. Bloomberg and New York brought with them considerable claims to material, reputational, and institutional capital, but it was the ability to link these to securing recognition for the cities of the C40 from external audiences – international financial institutions like the World Bank, multinational corporations, private capital markets – that authorized them to set the terms upon which such recognition would be granted within the governance field. In so doing the C40 began to converge toward a common set of governance norms – autonomy and global accountability – that underpin the production of coordinated action.

Convergence and coordination in the C40 emerged as a function of the authority of Michael Bloomberg and New York City to establish and project onto the governance field a particular set of governance norms and a sense of collective identity. This chapter demonstrates the extent to which convergence around those norms and identity not only continued, but also rather accelerated, following the shift in C40 leadership that took place in early 2014. The analytic focus thus shifts from an emphasis on agency – who claims authority, how actors attempt to shape the substance of the governance field – to the structuring effects that governance fields exert once those ideational and identity contours are entrenched. The chapter documents the extent to which the C40 governance field, from 2014-2018, consolidated around governance norms of autonomous agency and global accountability. The theory of global urban governance fields is deployed to illuminate the manner in which these norms constitute both the parameters within which member cities have come to understand and enact their role as global climate governors, and the mechanism of recognition through which these norms are replicated and reinforced across the C40.

The C40 is in many ways a success story. It has generated increased engagement and coordination, with the vast majority of member cities now committed to the collective goal of carbon neutrality by midcentury. This level of coordination was virtually unthinkable a mere decade ago, and the theory of global urban governance fields helps to identify and explain its origins and underpinnings. The ability of the C40 to generate convergence and consolidation around a common understanding of how to “be” a global urban climate governor has enabled the C40 to generate collective effort in the face of voluntary participation. This chapter sets out the ways in which this insight contributes to pushing forward the scholarship on cities, global climate governance, and the role of cities in international relations more broadly. It also highlights important questions that emerge as a result, including the relationship between the content of C40 norm/identity convergence and the potential contribution it can make to achieving collective goals of decarbonization and transformative sustainability, how to measure and assess progress and performance, and for whom/to whom cities are rendering themselves accountable as global climate governors.

The theory of global urban governance fields asserts that coordination in city-networks rests on convergence around a common set of ideas and practices that shape how member cities understand themselves as global climate governors. This chapter applies cluster analysis to a dataset containing both 10,000-plus unique climate governance actions, as well as the climate governance profiles (type and content of emissions reduction target, scope and methodology of emissions inventory, focus and scope of climate action plan) of all C40 cities, to infer the governance norms and collective identity around which the C40 governance field has been organized. The analysis posits two core ideational components – what kind of agency do cities possess, and how do they orient themselves to the global effort – and identifies convergence over time and space around two distinct responses: governance norms of autonomous agency and global accountability. These norms, in concert with practices of standardization, transparency, accounting, and disclosure, constitute a collective identity: the globally accountable urban governor. The chapter provides empirical referents for this process of normative and identity convergence, and establishes the connection between these and observations of increased coordination and collective effort.

While the C40 has come to claim a position of global leadership based on a demonstrated ability to generate coordinated action and collective effort, the description of the network presented in Chapter 1 signals that this has not always been the case. This chapter explores the early phase of the C40 (2005-2009) in which the network was characterized by uneven participation and an inability to engender network-wide engagement and coordination. Applying the theory of global urban governance fields brings to light the dynamics of competition and political contestation and links the observed lack of coordination to an inability to achieve convergence around a common identity. The Clinton Climate Initiative and the C40 Chair (occupied by the cities of London and Toronto) and Secretariat each sought to project divergent ideas with respect to how cities of the C40 should “do” global climate governance, yet neither was able to leverage the mechanism of recognition to effectively claim authority and give shape and substance to the governance field. As a result, the governance field remained fragmented and uncoordinated; split, as with so many other city-networks, into a small group of leading cities and a large group of laggards.