Urban areas are responsible for significant amounts of greenhouse gas (GHG) emissions, but cities can have quite different values of carbon footprints. The purpose of this paper is to identify the determinants of urban GHG emissions in order to explain these differences. Seven global cities – Bangkok, Chicago, London, Madrid, Mexico City, Milan and New York City – have been included in the paper's sample. These cases have been chosen in order to represent a variety of characteristics and contexts of developed and developing countries and according to data availability.