National audience This paper analyses the role of policies at local level to accompany the post-carbon transition as a complement to the global measures conventionally envisaged. Such measures are particularly justified to control transport-related emissions by allowing monitoring of mobility needs and modal shift. The analysis of these effects shall be carried out through an innovative modelling framework that provides a coherent representation of long-term economic trajectories and underlying urban dynamics. This tool is used in France to quantify the forward-looking scenarios defined under the “Rethinking Cities in a Post-Carbon Society” programme, co-piloted by the prospective mission of the CGDD — MEEDDM and the ADEME Economic and Prospective Service. They demonstrate the importance of the distribution of investments at local level on the nature of the post-carbon transition, be it in terms of local dynamics (city form, urban costs) or national trends (GDP, carbon emissions). This study highlights three key dimensions at local level for the post-carbon transition: agglomeration effects and links between productivity and density; the articulation between different levels of governance to combine local and global measures; the heterogeneity of the tempo of action, which makes it possible to think about the temporal tuilage of short- and long-term measures.