Over half of the global population is now living within urban settlements in which some three quarters of global resource consumption takes place. The environmental consequences of this urbanisation are both profound and increasing. It is thus important that our cities evolve in the most sustainable way possible. To guide this process it is useful to test the environmental consequences of alternative urban planning scenarios. To this end, we propose the development of a new advanced computer modelling paradigm and discuss progress that is under way to realise it.