Determining a sustainable city model

With the prediction by the United Nations that 60% of the world's population will live in cities by the year 2030, it is apparent that the immediate global future is one of urbanisation. Central to the issue of sustainability must therefore be the increasing domination of the city. Determining the sustainability of a city and the effect the city has on global sustainability must be considered from two perspectives that are largely analogous to Castells' bi-polar conflict between “the Net” and “the Self” [Castells, M., 1996. The Rise of the Network Society, vol. 1, first ed. Blackwell Publishers, Oxford, UK]. Cities must reconcile the conflict between being part of a competitive global city network and satisfying the day to day requirements of their own inhabitants. This dual perspective of cities and sustainability is examined in this paper with a view to determine an appropriate model for what may constitute a contemporary sustainable city. What are the defining characteristics that would ensure a city can not only survive in a manner acceptable to its current and future inhabitants, but also in a way that will not undermine the abilities of other cities and regions around the world to also remain sustainable?