London’s ability to remain a world-leading city in an increasingly globalised economy is dependent on it being an efficient and low risk place to do business. However, climate risks from flooding, overheating and water scarcity are increasing. Adaptation in dense urban areas, like London, will involve sustained effort, considerable cost and difficult choices. The Mayor of London has identified anticipatory adaptation as a cost effective strategy to increase the long-term resilience of the city. In practice however, the allocation of scarce resources to adaptation needs to be justified by evidence of the benefits of climate risk reduction. Analysis of sequential adaptation decision ‘pathways’ helps to demonstrate how climate risk can be managed, whilst retaining the flexibility to respond to future uncertainties.

The extensive analysis to plan London’s protection against tidal flooding is widely recognised as a pioneering instance of sequential risk-based decision-making. This paper demonstrates recent advances in the application of risk-based methodologies that are now being rolled out to address the risks of pluvial flooding, overheating and water scarcity in London to inform the development of long-term adaptation pathways. Pathways diagrams have been used to demonstrate how much risk reduction might be achieved under different scenarios. Quantifying and visualising climate risks has helped to reconcile multiple decision timescales and demonstrate to stakeholders the value of strategic long-term planning for climate change adaptation.