How urban spatial expansion influences CO2 emissions in Latin American countries

The way urban development will be shaped during the next decade will have a decisive impact on our ability to limit global temperature increase. The goal of this paper is to develop a better understanding of the relationship between carbon dioxide (CO2) emissions and the spatial expansion of cities to inform how urban planning can help shape low-carbon urban systems. To this end, a new methodology is proposed: cities are delineated based on a population-based clustering approach; and spatially disaggregated fossil fuel CO2 emissions are used to systematically evaluate the CO2 emissions of 635 cities across seven Latin American countries for the years 2000 and 2015. City spatial expansion is then characterized through the evolution of two indicators: population density, which is used to proxy city compactness; and the suburban ratio, which captures suburban sprawl and potential relocation effects. Using a spatial panel model, results unveil that a 1 % increase in density reduces CO2 emissions by 0.58 %, while a 1 % growth in the suburban ratio boosts emissions by 0.41 % ceteris paribus. These coefficients imply opposite CO2 effects for most Latin-American cities, which have experienced a concomitant increase in density and suburban ratio. Finally, city-level emissions are projected until 2030 using these elasticities and the growth rates associated with the three major spatial expansion patterns identified during the period 2000–2015. The findings are important for future planning purposes given that the 'compact expansion' model generates a 12 percentage points smaller increase in emissions than its passive counterpart. However, even under this compact scenario, city-level emissions grow faster than city population.