The urban metabolism of airline passengers: Scaling and sustainability

Abstract

Concerns about the negative externalities of air transport suggest it is important to consider the sustainability of growth in demand for air transport. However, there is little agreement on how the sustainability of demand should be evaluated. In this paper, I draw on the extensive literature on allometric scaling in biology, which examines animals’ demand for calories, to provide a novel framework for evaluating the sustainability of cities’ demand for air transport service. Viewing cities as analogous to organisms and airline passengers as analogous to life-sustaining resources, I focus on two questions. First, at what rate do cities metabolise passengers, that is, how many airline passengers does it take to fuel a city of a given size? Second, does this metabolic rate differ for business and leisure passengers, which represent different kinds of urban resources? Using data on airline passenger movement between 103 US metropolitan areas in each year from 1993 through 2011, I find that cities demand airline passengers in proportion to their population size, but when viewed separately, demand for business passengers as a function of city size is much lower than for leisure passengers. Moreover, I find that these patterns have remained relatively stable over the last two decades. The findings suggest that considering passenger type is important in evaluating the sustainability of air transport and the capacity of the air transport system to support cities’ continued growth.