Urban density and climate change: a STIRPAT analysis using city-level data

Two important, increasing trends for those concerned about climate change to consider are urbanization/the importance of cities and energy used in transport—particularly energy used to achieve personal mobility. While national urbanization levels are not a good indicator of urban transport demand, there is an established negative relationship between urban density and such demand. This paper uses a consistent, well-known population-based framework (the STIRPAT model) and three separate, but highly related, datasets of cities from developed and developing countries (with observations from 1990, 1995, and 2001) to examine the relationship among private transport energy consumption, population, income, urban density, and several variables (e.g., network size and prices) that describe the nature of the public and private transport systems of those cities. The paper confirms the now well-established result that urban density is negatively correlated with urban private transport energy consumption. In terms of policies, improving private vehicle fuel efficiency, in particular, and increasing fuel price as well as other ownership/operating costs for private transport could have a substantial impact on lowering transport energy consumption. On the other hand, there is no evidence that further lowering the cost to riders of public transport would lower private transport energy consumption. For cities in developing countries, demographic variables (population size and urban density) are particularly important in determining private transport energy consumption. Also, private transport energy consumption is considerably less price sensitive in those developing country cities compared to cities in the most developed countries.