Changes in storm surges in southern Europe from a regional model under climate change scenarios

Changes in storm surges in the Mediterranean Sea and the Atlantic Iberian coasts during the 21st century are explored based on the outputs of a numerical barotropic regional model. Three different climate scenarios (A2, A1B and B1) for the period 2000–2099 together with a control run for 1950–2000 have been simulated forced by greenhouse gases concentrations. A hindcast run for the 20th century (1958–2001) forced with a dynamical downscaling of ERA40 reanalysis has also been performed. Comparisons between hindcast and control run show consistency on their average statistics and their spatial distribution in terms of extreme events. Results for the 21st century reveal that storm surges frequency and magnitude decrease. Changes reach 50% in the number of events and up to 8 cm in the 50-year return levels. The analysis shows a progressive decrease in the return levels not fully explained by a negative trend in the mean atmospherically-induced sea level and a linear dependence with winter NAO. Likewise, negative events show the opposite behavior, with an increase in their frequency and magnitude although smaller than for positive surges.