Urban Land Expansion and Decreased Urban Sprawl at Global, National, and City Scales during 2000 to 2020

Abstract

Land area in urban use may be growing faster than population growth, increasing urban sprawl. With calibrated population density thresholds from the Worldpop population model, area and densities can be measured for suburban and urban density classes (≥ 250 humans per square kilometer) at global and national scales and both broad multi-city agglomerations and fine city cores during 2000 to 2020. Globally, net expansion of suburban and urban, urban, and high-density urban area was 930,000, 545,000, and 215,000 km2, respectively, with 25% to 35% of expansion located in India. Area containing suburban and urban densities increased from 3.4% to 4.1% of total land area. Density increased from 960 to 1,124.5 humans per square kilometer; density of the suburban class (250 to 800 humans per square kilometer) remained stable, while urban densities increased. Increased or stable densities occurred for nearly all countries and cities at both broad and fine scales, with the exception of 12 of 154 countries, 368 of 4,672 city agglomerations, and 523 of 12,008 city cores. Even though urban expansion occurred, as opposed to sustainable land use with growth boundaries, overall human densities increased. Human populations have become more concentrated, meaning that urban population densities are growing faster than the urban land base.