C40 Cities is an organization of Networked institutions—one of ten network types defined in the global solution Networks taxonomy. Members of C40 Cities are the mayors of megacities around the globe. Faced with urgent problems that have been caused in large part by climatic changes, the mayor-members of the C40 Cities network have determined that they cannot and will not wait for international agreements and initiatives that may take decades or longer to have any impact on the problems they face today.
In the decade since the organization was established, is has become one of the most effective agents working on the problems created by climate change. its local initiatives are tested, implemented and transmitted from city to city through the connections of members of the network and through the sub-networks that are developed in their annual meetings. C40 has a full time professional staff, and works with member cities to initiate actions and to measure and manage those actions with the tools and Web-supported data collection capabilities that are managed by the network staff and collated into complete reports to provide project status and challenges for member cities around the world.