Projections of extreme storm surge levels along Europe

TLDR

Storm surges are a key coastal hazard and their future evolution along Europe’s coast under climate change is unknown. The authors used Delft3D‑Flow driven by wind and pressure fields from an 8‑member climate ensemble to simulate storm surge dynamics for 1970‑2000 and for RCP4.5/RCP8.5, applying peak‑over‑threshold extreme value analysis to estimate future surge levels. Simulations show projected increases in extreme storm surge levels along the North European coast, especially under RCP8.5, while southern coastlines near 50°N see minimal change or slight decreases; combined sea‑level rise and surge increases could raise extreme water levels by over 30 % of RSLR for high return periods, underscoring urgent adaptation needs. The dataset is publicly available at http://data.jrc.ec.europa.eu/collection/LISCOAST.

Abstract

Storm surges are an important coastal hazard component and it is unknown how they will evolve along Europe’s coastline in view of climate change. In the present contribution, the hydrodynamic model Delft3D-Flow was forced by surface wind and atmospheric pressure fields from a 8-member climate model ensemble in order to evaluate dynamics in storm surge levels (SSL) along the European coastline (1) for the baseline period 1970–2000; and (2) during this century under the Representative Concentration Pathways RCP4.5 and RCP8.5. Validation simulations, spanning from 2008 to 2014 and driven by ERA-Interim atmospheric forcing, indicated good predictive skill (0.06 m < RMSE < 0.29 m and 10 % < RMSE < 29 % for 110 tidal gauge stations across Europe). Peak-over-threshold extreme value analysis was applied to estimate SSL values for different return periods, and changes of future SSL were obtained from all models to obtain the final ensemble. Values for most scenarios and return periods indicate a projected increase in SSL at several locations along the North European coastline, which is more prominent for RCP8.5 and shows an increasing tendency towards the end of the century for both RCP4.5 and RCP8.5. Projected SSL changes along the European coastal areas south of 50°N show minimal change or even a small decrease, with the exception of RCP8.5 under which a moderate increase is projected towards the end of the century. The present findings indicate that the anticipated increase in extreme total water levels due to relative sea level rise (RSLR), can be further enforced by an increase of the extreme SSL, which can exceed 30 % of the RSLR, especially for the high return periods and pathway RCP8.5. This implies that the combined effect could increase even further anticipated impacts of climate change for certain European areas and highlights the necessity for timely coastal adaptation and protection measures. The dataset is publicly available under this link: http://data.jrc.ec.europa.eu/collection/LISCOAST .