We face a huge challenge in satisfying the need for development that is sustainable in the long term, given our slow movement towards a low-carbon economy. Geoengineering is the deliberate, large-scale intervention in the Earth’s natural systems to address climate change. Which, if any, geoengineering proposals are technically feasible, and what the consequences might be, is something we need to know when considering our options. In this lecture, Richard Darton will look at the potential contribution of geoengineering and whether it offers a feasible future.