Dr Samuel Fankhauser makes the case for adaptation as a core part of the global policy response to climate change. He argues that adaptation is now unavoidable, because there are no realistic mitigation policies that restrict warming to a level that does not require substantial adaptation. A choice between adaptation and mitigation only exists in the long term, but this is not a trade off policy makers will make explicitly, because adaptation and mitigation choices are made by different actors. Adaptation is made more difficult by uncertainty about the exact nature of the expected change. This puts a premium on adaptations that yield early benefits or increase the flexibility of systems to react to unexpected change.