Uncertainty in climate change impacts on water resources

The uncertainty concepts play a prominent role in global environmental change research, including climate change science and climate change impact science, with hydrology and water resources research in particular. One is uncertain, to varying degrees, about virtually everything in the future as well as about much of the past and the present state. The present paper reviews applications of the uncertainty notion to results of change detection, process understanding and modeling of systems, and - foremost - projections of future climate change impacts on water resources. We present a framework of assessing and reducing uncertainty and propose measures that could improve uncertainty communication, e.g. relying on ensembles and multi-model probabilistic approaches rather than projecting ranges of values. We distinguish two possible management strategies if uncertainty is irreducible - the precautionary principle and the adaptive management.