Testing the efficacy of voluntary urban greenhouse gas emissions inventories

Drawing from an original dataset of urban metropolitan carbon footprints, we explore the correlations between national level climate change commitments and subnational level inventories. We ask: Does voluntary reporting allow a city to perform better than national average? Does ambitiousness in commitment have an impact on performance in footprint reduction? Does having long-term commitments affect performance in footprint reduction? Do binding national level commitments (such as those under the Kyoto Protocol) affect performance at the city level in terms of footprint reduction? To provide answers, we synthesize data from the largest repository of voluntary sub-national commitments and actions towards footprint reduction and greenhouse gas inventories from around the world, the Carbonn platform. More than 500 cities report at least one action, commitment or inventory to this database. We find, using a subset of this database, perhaps counter intuitively that cities with more ambitious commitments do not necessarily have steeper reductions in emissions. Our data also suggest that having long-term self-reported goals does not make the cities perform better in terms of footprint reduction. This appears to be true for both government and community commitments reported. Lastly, and positively, our data did reveal a statistically significant effect for cities belonging to countries that had committed to the Kyoto Protocol, suggesting the necessity of binding national (and supranational) climate targets.