Climate Change Prediction

With increasing concerns about climate change, a major international effort is underway to understand the causes and predict the likely impacts, including on floods, droughts and water resources. At an international level, climate model projections are submitted to the WMO Coupled Model Intercomparison Project (CMIP), based on plausible emission and land use change scenarios. These then underpin the IPCC assessments of potential changes in climate. Hydrological impacts are then assessed at a local, regional or national level by running scenarios through models, often using a selection of CMIP outputs. Physical-conceptual rainfall-runoff models are widely used, sometimes combined with decision support tools such as water allocation models. Predictions are necessarily probabilistic and are typically for timeslices of 10–30 years. This chapter provides an introduction to these various topics and more generally discusses current and potential uses of process-based models such as land surface models in improving predictions. Some current research themes on assessing hydrological impacts are also discussed including the findings from expert elicitation exercises and the use of experimental catchments to better understand climate risks.