Urban compactness and carbon emissions: global evidence over the period 1975-2020

The share of population living in urban centres has vastly increased in recent decades, and is predicted to further expand in the future. In this context, research on the environmental impact of different urban environments, in terms of both the form and built-up structure of cities, is particularly important to understand whether smart urban design can help mitigate the nefarious impacts of climate change. This study aims at investigating relevant associations between urban form (and specifically, urban compactness) and carbon dioxide emissions of the residential and on-road transport sectors on a global scale over a long time period. By relying on a recently established, internationally comparable definition of “urban centre”, several GIS-based measures of urban form have been calculated for 11,435 cities over the period 1975–2020 and have been associated to city carbon emissions. The results show that lower levels of emissions of the residential and transport sectors occur in urban environments taking on more compact shapes especially in Africa and Asia, whereas the impact of urban compactness is found to be limited in Europe and North America. This heterogeneity suggests that the effect of urban containment policies may be substantial in developing countries and almost null in more developed areas.