“Making room for a planet of cities”: From planet of cities (2012)

In this selection from Planet of Cities (2012), architect Shlomo Angel explores the way city regions have evolved and will continue to evolve in the globalized future. Many urbanists have argued that the world could not sustain the current pattern of development, that cities are responsible for much of the world’s greenhouse gas emissions, and that only strategies for sustainable urban development can turn things around. All these arguments point toward the need to understand, plan, and manage city-regions on a planetary level. Angel’s research is based on statistical and spatial analysis of data on 3, 646 large cities worldwide with more than 100, 000 people. He provides both cross-sectional analysis describing the population, area, and fragmentation of land uses in world cities and longitudinal analysis showing how they have changed over time. His uses computer tools to marshal data, analyze it, and then construct theory from facts. His research provides insights into important questions that have important implications for planning. He notes that urban land cover has been growing very rapidly, but in the year 2000 cities covered less than one-half of one percent of the earth’s land area. While city populations have also been growing rapidly, he found that in the final decade of the twentieth century city populations grew at less than half the rate that urban land cover grew. Urban densities have actually been declining almost everywhere for more than a century if one considers the entire urban area, and Angel feels there is no possibility that the global decline in urban densities will slow down any time soon. In terms of centrality and dispersal, Angel describes two sequential transformations: first, from the monocentric city to a regional form with jobs in the center and housing in suburbs; and then, in a second transformation, to a polycentric network of cities with both housing and work decentralized.