The contribution of cities to climate change is significant, but cities are not all the same. City rankings and comparisons should take into account that differences in the Carbon Footprint of cities can be related to different stages of economic development, geographical conditions, social or political factors, or specific public policies – that all shape and are shaped by national contexts. The Relative Carbon Footprint is a measure that takes these factors into account and can be a useful a tool for both national and local urban policy makers for the identification of strategic emissions sectors. For policy makers at the national level, the Relative Carbon Footprint offers concrete insights on the conditions under which particular cities are a driver of national GHG emissions or are a solution for reducing them, by highlighting the particularities of a specific urban system vis-à-vis its national counterpart. At the city level, the RCF enables vertically integrated policy making for a city by considering it within its national context, and provides indications on how to draw environmental priorities based on feasibility and expected returns. In particular, the findings of our research focused on São Paulo and Cape Town draw attention to three dimensions of influence on the Relative Carbon Footprint: the ways that energy is produced and supplied at the city and country level (the energy matrix), the average levels of income, and the structure of the economy of the city and the country.
