Measuring whether municipal climate networks make a difference: the case of utility-scale solar PV investment in large global cities

With cities being responsible for up to 70% of energy-related carbon emissions, municipal governments worldwide are becoming increasingly aware of their responsibility to act. Many large cities have committed to mitigation by becoming member of a municipal climate network, such as the C40 or the Compact of Mayors. However, there is no consistent assessment of whether membership of such networks translates into measurable outcomes. To fill this gap, we propose the use of novel outcome variables, combining financial data with geospatial information. As a starting point, this paper compares utility-scale investment in photovoltaics (PV) within the administrative boundaries of large global cities, combining the Bloomberg New Energy Finance database with information from Google Maps. We analyse 512 global cities with a population of above 1 million, and consider the impact of 5 networks and 2 reporting platforms. The results suggest that membership of the C40 network has a positive effect on utility-scale solar PV investment, while no such evidence is found for any of the other networks or reporting platforms under study. Based on our findings, we recommend that municipal climate networks increase their efforts to trigger city regulation that is conducive to solar PV investment. More generally, measuring early indicators, such as low-carbon investment, can help municipal climate networks in their role as 'commitment brokers' for climate action on the ever-more important city level.Key policy insights Cities have considerable policy space to foster utility-scale solar PV investment within their administrative boundaries. While some large global cities exhibited significant growth in utility-scale solar PV, many others with good solar potential did not have a single project by the end of 2016. Outside of China (where city boundaries often include rural areas), Tokyo tops the list with utility-scale solar PV projects by far, followed by San Diego and Rome. Membership of the C40 network appears to make a positive difference to PV investment, unlike other networks or reporting platforms. Outcome measures like low-carbon investment can be used more generally to assess the climate action performance of cities.