The overall objective of this review is to analyse to what extent international city networks like C40 may leverage cities activities in relation to effective and efficient GHG abatement.

The underlying assumption for the review is that city networks add value by reducing transaction costs (efficiency hypothesis) and accelerate learning, replication and scale (network hypothesis), eg. by:

• lowering transaction costs and accelerating partnerships formation (one-stop-shop approach)
• improving the evidence base (data and sharing of lessons learned)
• prioritizing and catalyzing demonstration efforts and accelerating the process of replication and scale-up
• reducing political risks (as working across a number of cities rather than focusing on one or two)
• acting as an honest broker (an independent unbiased approach to finance, etc)
• empowering cities as a group by supporting joint advocacy
• ensuring peer accountability for the worst performers
• triggering competition among the best performers › facilitating peer-to-peer learning