A systematic approach to assessing the sensitivity and vulnerability of water availability to climate change in Europe

Making use of ensemble climate modeling systems and multimodel simulations of climate projections calls for a systematic approach in impact studies. In this study the response surface method is introduced to systematically, consistently, and objectively examine impacts of climate change on water availability, subject to selected impact thresholds. The response surface hereby represents the sensitivity of water availability to a broad range of possible climatic change, onto which vulnerability thresholds are superimposed. Their exceedance is assessed by additionally superimposing climate change projections onto the surface. With this method, 18 European river basins are ranked according to their sensitivity to climate change (analyzing the response surface itself). The use of climate change projections from six regional climate models for the year 2100 under the Intergovernmental Panel on Climate Change A1B emissions scenario in combination with societal vulnerability thresholds then enables a vulnerability ranking of these basins. Overall, a strong climate sensitivity of the Nordic basins is found on the basis of their mainly snow-dominated flow regime. When looking at the vulnerability, however, southern European basins together with some central European basins are highest in the ranking because of the violation of both low flow and water stress thresholds.