Vision 2030 : the resilience of water supply and sanitation in the face of climate change : climate change projection study

This study is aiming to inform adaptation to climate change strategies in the sector of water supply and sanitation technologies. The decadal prediction system (DePreSys) is used here as the basis for predictions of changes in precipitation, all around the world, over the next 20 years. Two time frames during this period are selected for illustration: the 9-year periods centred on 2020 and 2030 respectively. Predictions are provided for annual, seasonal and monthly averages, as well as for some large-scale extreme events. The model predictions are subject to uncertainties, an estimate of which is provided alongside the prediction maps in the report. Predictions and associated uncertainties will be used, together with regional information on the status of water supply and sanitation technologies, to help develop strategies for adaptation. A rigorous quantitative assessment of the reliability (by ‘predicting’ past cases) is not possible at this stage, but case studies presented in this report show that plausible predictions of annual-mean precipitation over large-scale areas are achievable with DePreSys. In light of the considerations made in the report, the predictions presented may be cautiously used to gauge large-scale patterns of change across the globe; they should not be used for applications which require small-scale details.