Urban ecosystems: the human dimension

This paper develops a human ecological perspective on cities and urban regions. It describes the role of cities in the expanding human ecological niche and its implications for sustainable urban development. I have used a new technique, ecological footprint analysis, to convert the material and energy flows required to sustain the human population and industrial metabolism of the city into a landecosystem area equivalent. This approach emphasizes that, although urbanization has become the dominant human settlement pattern, cities themselves constitute only a small part of the total ecological space appropriated by their human inhabitants. In short, the ecological locations of human settlements no longer coincide with their geographic locations. Every city and urban region depends for its existence and growth on a globally diffuse productive hinterland up to 200 times the size of the city itself. Cities are therefore increasingly vulnerable to global ecological change and geopolitical instability. Given the deteriorating state of the ecosphere, policies to decrease the ecological footprint of cities while increasing regional self-reliance may enhance urban sustainability.