The dimensions of global urban expansion: Estimates and projections for all countries, 2000-2050

Shlomo Angel, Jason Parent, Daniel L. Civco, Alexander Blei, David Potere

Research output: Contribution to journalArticle

Abstract

Our study of the expansion of a representative sample of 30 cities showed that 28 of them expanded more than 16-fold during the twentieth century. More generally, cities are now expanding at twice their population growth rates, on average, and now cover almost 0.5% of the planet's land area. We created a new dataset comprising the universe of all 3646 named metropolitan agglomerations and cities that had populations in excess of 100,000 in the year 2000, their populations in that year, and their built-up area identified in the Mod500 map, currently the best of eight satellite-based global maps of urban land cover. Using this dataset, we estimated urban land cover in smaller cities and towns in all countries and calculated total urban land cover in every country in the year 2000. We then employed multiple regression models that could explain more than 90% of the variations in our urban land cover estimates amongst countries. Then, using U.N. urban population projections in combination with three realistic density change scenarios based on our previous global and historical study of densities, we projected urban land cover in every country and world region from 2000 to 2050. According to our medium projection, urban land cover in developing countries will increase from 300,000km2 in 2000 to 770,000km2 in 2030 and to 1,200,000km2 in 2050. Containing this expansion is likely to fail. Minimal preparations for accommodating it - realistic projection of urban land needs, the extension of metropolitan boundaries, acquiring the rights-of-way for an arterial road grid that can carry infrastructure and public transport, and the selective protection of open space from incursion by formal and informal land development - are now in order.

Original languageEnglish (US)
Pages (from-to)53-107
Number of pages55
JournalProgress in Planning
Volume75
Issue number2
DOIs
StatePublished - Feb 1 2011

Keywords

  • Built-up area
  • City growth
  • Satellite imagery
  • Sprawl
  • Urban expansion
  • Urban land cover
  • Urban population density
  • Urbanisation

ASJC Scopus subject areas

  • Geography, Planning and Development

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