Previous studies have found an inverse (or negative) correlation between urban population density and per capita emissions from land transport. In contrast, this paper finds a positive relationship between per capita CO2 emissions from transport and population density using a dataset of over 200...

The analysis finds that in addition to U-shaped paths of environmental quality arising for growth in income per capita, growth in population can also produce socially efficient patterns that are U-shaped. Sufficient conditions for both types of paths are identified for a range of models and...