"While nations talk, cities act." This quote from Mike Bloomberg, the former New York mayor, reflects the frequent portrayal of the role of cities and local governments in global climate governance: in light of concerns about the inability of national governments to agree on and achieve sufficient emissions reductions, cities and transnational city networks are often seen as actors that could fill that gap.

While hardly anyone would argue against the importance of cities and local governments in the implementation of climate policies, what remains contested is their role in the international climate regime. The analysis conducted in this book chapter uncovers how the activities of cities and transnational city networks, which have been evolving over the years, have gradually broadened the international climate regime, even though cities are not subjects of international law.

In more detail, the analysis suggests that the participation of cities in the international climate regime goes beyond the usual role of stakeholders in similar intergovernmental processes with ministerial-mayoral dialogues, visibility on the official agenda, discussions with the COP Presidency and recognition as governmental stakeholders in the Cancun Agreements in 2010. Moreover, several forums were created or strengthened in the run up to Paris as well as at COP21 to allow for better exchange between state and city representatives. While these platforms and forums are not a formal part of the negotiation process, they are closely linked to the negotiations, thus offering increasing visibility, legitimacy and motivation for the climate protection efforts of city actors. More recently, the IPCC has also emphasised actions undertaken by cities in its work.

In conclusion, global climate institutions and organisations can learn from and are being influenced by the experiences and insights gained at city level and the increased efforts of cities over the years are slowly being accommodated by the international climate regime.