A framework for developing high-resolution multi-model climate projections: 21st century scenarios for the UK

This article proposes a framework for building climate projections from an ensemble of global circulation models (GCMs) at the local scale required for impact studies. The proposed method relies on a fine-scale gridded baseline climatology and consists of the following steps: (1) building appropriate precipitation and temperature time series from land areas covered by GCM sea cells; (2) correction of GCM outputs inherent biases through 'quantile-based mapping'; and (3) disaggregation of bias-corrected outputs with monthly spatial anomalies between GCM-specific and observed spatial scales. The overall framework is applied to derive 21st century seasonal climate projections and inter-annual variability for the UK based on an ensemble of six GCMs run under two different emissions scenarios. Results show a large dispersion of changes within the multi-GCM ensemble, along with a good comparison between scenarios from individual ensemble members and from previous UK and European studies using dynamically downscaled outputs from corresponding GCMs. The framework presented in this article provides appropriate outputs to take account of the uncertainty in global model configuration within impacts studies that are influencing current decisions on major investments in flood risk management and water resources. Copyright (C) 2007 Royal Meteorological Society.