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.

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.