Integrated assessment models - from global to local

This illustrated commentary looks at two very different types of integrated assessment models in context. On one hand the current generation of integrated climate models has achieved a significant role in environmental policy. On the other, integrated models for urban and regional systems have declined in their relevance for the policy process. However, the global models should be closely linked to urban models, which provide a very significant part of their inputs. This leads us to consider the modelling paradigm and future directions in technical tools which link science and policy. A city-region case study provides one example of a response-a deliberately simple and transparent scenario-building model, as a practical link in the problem-solution cycle.