Space-based quantification of per capita CO2 emissions from cities
Urban areas are currently responsible for ~70% of the global energy-related carbon dioxide (CO2) emissions, and rapid ongoing global urbanization is increasing the number and size of cities. 
Thus, understanding city-scale CO2 emissions and how they vary between cities with different urban densities is a critical task. While the relationship between CO2 emissions and population density has been explored widely in prior studies, their conclusions were sensitive to inconsistent definitions of urban boundaries and the reliance upon CO2 emission inventories that implicitly assumed population relationships.