Landscape Ecology

, Volume 29, Issue 5, pp 763–771 | Cite as

How much of the world’s land has been urbanized, really? A hierarchical framework for avoiding confusion

  • Zhifeng Liu
  • Chunyang HeEmail author
  • Yuyu Zhou
  • Jianguo Wu


Urbanization has transformed the world’s landscapes, resulting in a series of ecological and environmental problems. To assess urbanization impacts and improve sustainability, one of the first questions that we must address is: how much of the world’s land has been urbanized? Unfortunately, the estimates of the global urban land reported in the literature vary widely from less than 1–3 % primarily because different definitions of urban land were used. To evade confusion, here we propose a hierarchical framework for representing and communicating the spatial extent of the world’s urbanized land at the global, regional, and more local levels. The hierarchical framework consists of three spatially nested definitions: “urban area” that is delineated by administrative boundaries, “built-up area” that is dominated by artificial surfaces, and “impervious surface area” that is devoid of life. These are really three different measures of urbanization. In 2010, the global urban land was close to 3 %, the global built-up area was about 0.65 %, and the global impervious surface area was merely 0.45 %, of the word’s total land area (excluding Antarctica and Greenland). We argue that this hierarchy of urban land measures, in particular the ratios between them, can also facilitate better understanding the biophysical and socioeconomic processes and impacts of urbanization.


Urbanization Global urban land Urban area Built-up area Impervious surface Hierarchy of definitions 



We would like to thank two anonymous reviewers and the handling editor for their valuable comments on the paper. The research was supported by the National Basic Research Program of China (Grant No. 2010CB950901, No. 2014CB954302, and No. 2014CB954303) and the National Natural Science Foundation of China (Grant No. 41222003 and No. 41321001).


  1. Angel S, Sheppard SC, Civco DL (2005) The dynamics of global urban expansion. The World Bank, Washington DCGoogle Scholar
  2. Angel S, Parent J, Civco DL, Blei A, Potere D (2011) The dimensions of global urban expansion: estimates and projections of all countries, 2000–2050. Progr Plan 75:53–107CrossRefGoogle Scholar
  3. Bartholome E, Belward AS (2005) GLC2000: a new approach to global land cover mapping from Earth observation data. Int J Remote Sens 26(9):1959–1977CrossRefGoogle Scholar
  4. Buyantuyev A, Wu JG (2010) Urban heat islands and landscape heterogeneity: linking spatiotemporal variations in surface temperatures to land-cover and socioeconomic patterns. Landscape Ecol 25(1):17–33CrossRefGoogle Scholar
  5. CIESIN, IFPRI, CIAT (2011) Global Rural-Urban Mapping Project, Version 1 (GRUMPv1): Urban Extents Grid. NASA Socioeconomic Data and Applications Center (SEDAC)Google Scholar
  6. Connors J, Galletti C, Chow WL (2013) Landscape configuration and urban heat island effects: assessing the relationship between landscape characteristics and land surface temperature in Phoenix, Arizona. Landscape Ecol 28(2):271–283CrossRefGoogle Scholar
  7. Demographia (2012) Demographia world urban areas. Accessed 22 July 2012
  8. Douglas I (1994) Human settlements. In: Meyer WB, Turner BL II (eds) Changes in land use and land cover: a global perspective. Cambridge University Press, CambridgeGoogle Scholar
  9. Elvidge CD, Tuttle BT, Sutton PC, Baugh KE, Howard AT, Milesi C, Bhaduri BL, Nemani R (2007) Global distribution and density of constructed impervious surfaces. Sensors 7(9):1962–1979Google Scholar
  10. Elvidge CD, Tuttle BT, Sutton PC (2010) Collaborative tool for collecting reference data on the density of constructed surfaces worldwide. Proc SPIE 7840(78400k):1–8Google Scholar
  11. ESA (2011) GLOBCOVER 2009 products description and validation report. Accessed 22 July 2012
  12. Fragkias M, Seto KC (2012) The rise and rise of urban expansion. Accessed 22 July 2012
  13. Gamba P, Herold M (2009) Global mapping of human settlement: experiences, datasets and prospects. CRC Press, Boca RatonCrossRefGoogle Scholar
  14. Goldwijk KK, Beusen A, Janssen P (2010) Long-term dynamic modeling of global population and built-up area in a spatially explicit way: HYDE 3.1. Holocene 20(4):565–573CrossRefGoogle Scholar
  15. Grimm NB, Faeth SH, Golubiewski NE, Redman CL, Wu J, Bai X, Briggs JM (2008) Global change and the ecology of cities. Science 319(5864):756–760Google Scholar
  16. Irwin EG, Bockstael NE (2007) The evolution of urban sprawl: evidence of spatial heterogeneity and increasing land fragmentation. Proc Natl Acad Sci USA 104(52):20672–20677PubMedCentralPubMedCrossRefGoogle Scholar
  17. Loveland TR, Reed BC, Brown JF, Ohlen DO, Zhu Z, Yang L, Merchant JW (2000) Development of a global land cover characteristics database and IGBP DISCover from 1 km AVHRR data. Int J Remote Sens 21(6–7):1303–1330Google Scholar
  18. McIntyre NE (2011) Urban ecology: definitions and goals. In: Douglas I, Goode D, Houck M, Wang R (eds) The Routledge handbook on urban ecology. Routledge Press, New YorkGoogle Scholar
  19. McIntyre NE, Knowles-Yanez K, Hope D (2000) Urban ecology as an interdisciplinary field: differences in the use of “urban” between the social and natural sciences. Urban Ecosyst 4(1):5–24CrossRefGoogle Scholar
  20. Moody A, Woodcock CE (1995) The influence of scale and the spatial characteristics of landscapes on land-cover mapping using remote sensing. Landscape Ecol 10(6):363–379CrossRefGoogle Scholar
  21. Myint S, Wentz E, Brazel A, Quattrochi D (2013) The impact of distinct anthropogenic and vegetation features on urban warming. Landscape Ecol 28(5):959–978CrossRefGoogle Scholar
  22. O’Meara M (1999) Reinventing Cities for People and the Planet. Worldwatch Paper 147. Worldwatch Institute, Washington DCGoogle Scholar
  23. Potere D, Schneider A (2007) A critical look at representations of urban areas in global maps. Geo J 69(1–2):55–80Google Scholar
  24. Potere D, Schneider A, Angel S, Civco DL (2009) Mapping urban areas on a global scale: which of the eight maps now available is more accurate? Int J Remote Sens 30(24):6531–6558CrossRefGoogle Scholar
  25. Raciti SM, Hutyra LR, Rao P, Finzi AC (2012) Inconsistent definitions of “urban” result in different conclusions about the size of urban carbon and nitrogen stocks. Ecol Appl 22(3):1015–1035PubMedCrossRefGoogle Scholar
  26. Ridd MK (1995) Exploring a V-I-S (Vegetation-impervious surface-soil) model for urban ecosystem analysis through remote sensing: comparative anatomy for cities. Int J Remote Sens 16(12):2165–2185CrossRefGoogle Scholar
  27. Schneider A, Friedl MA, Mclver DK, Woodcock CE (2003) Mapping urban areas by fusing multiple sources of coarse resolution remotely sensed data. Photogramm Eng Remote Sens 69(12):1377–1386CrossRefGoogle Scholar
  28. Schneider A, Friedl MA, Potere D (2009) A new map of global urban extent from MODIS satellite data. Environ Res Lett 4(4):1–11CrossRefGoogle Scholar
  29. Schneider A, Friedl MA, Potere D (2010) Mapping global urban areas using MODIS 500-m data: new methods and datasets based on ‘urban ecoregions’. Remote Sens Environ 114(8):1733–1746CrossRefGoogle Scholar
  30. Shao GF, Wu JG (2008) On the accuracy of landscape pattern analysis using remote sensing data. Landscape Ecol 23(5):505–511CrossRefGoogle Scholar
  31. Sutton PC, Elvidge CD, Tuttle BT, Ziskin D, Baugh KE, Ghosh T (2010) A 2010 mapping of the constructed surface area density for S.E. Asia—Preliminary results. In: Proceedings of the 30th Asia-Pacific Advanced Network Meeting. pp. 182–190Google Scholar
  32. Weng Q (2012) Remote sensing of impervious surfaces in the urban areas: requirements, methods, and trends. Remote Sens Environ 117(15):34–49CrossRefGoogle Scholar
  33. Wickham JD, Riitters KH (1995) Sensitivity of landscape metrics to pixel size. Int J Remote Sens 16(18):3585–3595CrossRefGoogle Scholar
  34. Woodcock CE, Strahler AH (1987) The factor of scale in remote sensing. Remote Sens Environ 21(3):311–332CrossRefGoogle Scholar
  35. Wu JG (2004) Effects of changing scale on landscape pattern analysis: scaling relations. Landscape Ecol 19(2):125–138CrossRefGoogle Scholar
  36. Wu JG (2007) Scale and scaling: a cross-disciplinary perspective. In: Wu J, Hobbs R (eds) Key Topics in Landscape Ecology. Cambridge University Press, Cambridge, pp 115–142CrossRefGoogle Scholar
  37. Wu JG (2013a) Hierarchy theory: an overview. In: Rozzi R, Callicott JB, Pickett STA, Armesto JJ (eds) Linking ecology and ethics for a changing world: values, philosophy, and action. Springer, New YorkGoogle Scholar
  38. Wu JG (2013b) Key concepts and research topics in landscape ecology revisited: 30 years after the Allerton Park workshop. Landscape Ecol 28(1):1–11CrossRefGoogle Scholar
  39. Wu JG (2013c) Landscape sustainability science: ecosystem services and human well-being in changing landscapes. Landscape Ecol 28(6):999–1023CrossRefGoogle Scholar
  40. Wu JG (2014) Urban ecology and sustainability: the state-of-the-science and future directions. Landsc Urban Plann. doi:  10.1016/j.landurbplan.2014.01.018
  41. Zhou WQ, Qian YG, Li XM, Li WF, Han LJ (2014) Relationships between land cover and the surface urban heat island: seasonal variability and effects of spatial and thematic resolution of land cover data on predicting land surface temperatures. Landscape Ecol 29(1):153–167. doi:  10.1007/s10980-013-9950-5

Copyright information

© Springer Science+Business Media Dordrecht 2014

Authors and Affiliations

  • Zhifeng Liu
    • 1
  • Chunyang He
    • 1
    Email author
  • Yuyu Zhou
    • 2
  • Jianguo Wu
    • 1
    • 3
  1. 1.Center for Human-Environment System Sustainability (CHESS), State Key Laboratory of Earth Surface Processes and Resource EcologyBeijing Normal UniversityBeijingChina
  2. 2.Pacific Northwest National LaboratoryCollege ParkUSA
  3. 3.School of Life Sciences and School of SustainabilityArizona State UniversityTempeUSA

Personalised recommendations