Projecting Global Urbanization and the Growth of Megacities

Abstract

Purpose – The purpose of this chapter is to project the global emergence of megacities through the 21st century using population scenarios consistent with the Special Report on Emissions Scenarios (SRES) of the Intergovernmental Panel on Climate Change (IPCC). Methodology – A dynamic urban growth model is developed based on a scale-independent theory of growing networks taking into consideration the geographical and climatic suitability of the location of cities. The model is able to generate a series of megacity projections consistent with an experimental city size distribution based on a national urban population scenario consistent with Zipf's law. The model is applied to population projections for 45,316 cities around the world using three population scenarios from SRES. Findings – All of the projections indicate that a large number of megacities will be generated in developing regions towards 2100, although the range is wide and depends on the population assumed in the scenarios. Some results indicate an extreme population concentration in megacities; this might be undesirable for national security, quality of life, and sustainable development. Transport policies affect urban growth and national land development through changes in mobility and accessibility across the nation. Implications – The results presented in this chapter could serve to stimulate discussions on urban and national transport policies and planning, particularly in China.