Current understanding of climate change impacts on extreme events

Water related issues are prominent amongst the commonly identified impacts of climate change. The issue of uncertainty remains highly pertinent, particularly for projections of changes in climate and the subsequent impact on hydrological extremes. An alternative to the traditional top-down impact studies are the bottom-up, vulnerability-based, approaches, which focus on sensitivity testing and adaptation options rather than climate change projections. A case study of such an approach to inform climate change policy development for flood management in Great Britain is described in this chapter. To assess the impact of climate change on hydrological droughts a multi-model experiment was undertaken, including seven global impact models (GIMs) driven by climate data from five global climate models (GCMs). This study demonstrates that different representations of terrestrial water cycle processes in GIMs can be responsible for considerable uncertainty in the response of hydrological drought to climate change.