Future Wave Climate in the Mediterranean Sea and Associated Uncertainty From an Ensemble of 31 GCM-RCM Wave Simulations

Abstract

Storm-driven waves significantly increase coastal hazards, especially in densely populated and infrastructure-rich regions like the Mediterranean, which is a major global hub for tourism, cultural heritage, and shipping. Although the basin has a fetch-limited environment, extra-tropical cyclones can still produce high waves. With increasing global temperatures altering the climate system, wave climate changes are anticipated, albeit with varying reliability across modeled climate variables. This study investigates projected wave climate changes in the Mediterranean using an extensive ensemble of EURO-CORDEX GCM-RCMs wave simulations based on the high-emission scenario RCP8.5. We assess future shifts in wave climate statistics while incorporating model variability for comprehensive results. Consistent with previous studies, our results indicate an overall reduction in significant wave height $\left(H_s\right)$, with reductions up to 0.45 m in autumn and winter, alongside significant shifts in wave direction. The future extreme wave climate changes were further evaluated by computing 100-year $H_s$ return levels. Extreme event distributions from all simulations were bias-corrected and aggregated into a single coherent distribution for each period. Our findings reveal for the first time robust evidence of intensification of extreme waves toward the end of the century in several regions of the Mediterranean, with increases of 0.50–2 m in $H_s$. While focusing solely on a high-emission scenario limits the scope of these findings for mitigation strategies, this study underscores the need to analyze both full and extreme distributions in wave climate projections. Each may have distinct implications for coastal management policies and maritime operations.