Complexity, the science of cities and long-range futures

The emergence of a ‘science of cities’ provides the foundations for long-range futures research that may be applied to models of climate change, with a time horizon in excess of 150 years. The features of a complexity theory of cities have been developed at multiple levels with scientific analogies such as ecology, biology and physics. The following principles apply: (1) complexity science unifies a wide variety of urban phenomena including emergence, technological evolution, civil phase transitions, macrolaws, and resilience to system failures and extreme events. (2). World urbanisation raises the number of levels in the urban hierarchy, with an increasing number of megacities with over 10 m inhabitants. (3) Urban development involves the institutional coordination of technological development with engineered transformations. (4) Civil and societal transitions arise with increasing per capita investment, such that some social norms and planning standards have consistent scaling factors across a range of city sizes for countries at similar stages of development. (5) The trajectory of the urban system depends upon the allometric pattern of growth for cities, and human settlements in 2150 will occupy less than 10% of the world's land area.

► Complexity theories of cities unify a wide variety of urban phenomena.
► The institutional coordination of urban technology leads to city transformations.
► Cities diffuse investment capital with gradients in investment returns, phase transitions and chaos.
► Some social norms and planning standards scale across a range of city sizes.
► The trajectory of the urban system provides a framework for long-range futures research.