Articles | Volume 20, issue 5
Research article
10 May 2016
Research article |  | 10 May 2016

High-end climate change impact on European runoff and low flows – exploring the effects of forcing biases

Lamprini V. Papadimitriou, Aristeidis G. Koutroulis, Manolis G. Grillakis, and Ioannis K. Tsanis

Abstract. Climate models project a much more substantial warming than the 2 °C target under the more probable emission scenarios, making higher-end scenarios increasingly plausible. Freshwater availability under such conditions is a key issue of concern. In this study, an ensemble of Euro-CORDEX projections under RCP8.5 is used to assess the mean and low hydrological states under +4 °C of global warming for the European region. Five major European catchments were analysed in terms of future drought climatology and the impact of +2 °C versus +4 °C global warming was investigated. The effect of bias correction of the climate model outputs and the observations used for this adjustment was also quantified. Projections indicate an intensification of the water cycle at higher levels of warming. Even for areas where the average state may not considerably be affected, low flows are expected to reduce, leading to changes in the number of dry days and thus drought climatology. The identified increasing or decreasing runoff trends are substantially intensified when moving from the +2 to the +4° of global warming. Bias correction resulted in an improved representation of the historical hydrology. It is also found that the selection of the observational data set for the application of the bias correction has an impact on the projected signal that could be of the same order of magnitude to the selection of the Global Climate Model (GCM).

Short summary
A set of the new Euro-CORDEX projections is used to examine the impact of high-end scenarios on water availability and stress at a pan-European scale. Drought climatology is investigated for five major European basins along with the impact of +2 °C versus +4 °C warming. The effect of bias correction is also examined. The selection of the observational data set used for bias adjustment has an impact on the projected signal that could be of the same order of magnitude as the selection of the RCM.