Increasing Daily Extreme and Declining Annual Precipitation in Southern Europe: A Modeling Study on the Effects of Mediterranean Warming

Abstract. Understanding the evolving patterns of intense rainfall in the Mediterranean under climate change is an urgent challenge. An analysis of the annual total and maximum one-day precipitation from 1955 to 2023 performed with the ERA5-Land dataset over the EURO-CORDEX domain reveals emerging patterns of contrasting trends along much of the northern Mediterranean coast, with heavy precipitation events increasing and total annual rainfall decreasing. An independent investigation on a ground-based dense monitoring network in southern Italy confirms the results. We focus on this representative sub-region of the study area to examine in detail the role of sea-atmosphere-orography interactions, particularly the impact of increasing sea surface temperature (SST), in enhancing heavy precipitation despite overall drying. Twenty consecutive precipitation events identified in a particularly intense rainy season (September–December 2019) are reproduced at a convection-permitting resolution (2 km) using the Weather Research and Forecasting (WRF) model with ERA5 reanalysis boundary conditions. Then, two scenarios are tested: one with past SST levels approximating 1980 and another with future SST increases in line with end-of-century Shared Socioeconomic Pathways (SSPs) projections. WRF simulations thoroughly describe cyclone tracks and precipitation patterns, showing that increased SST boosts the frequency of heavy rainfall events overland, though peak intensities remain mostly unchanged because the highest precipitations occur over the sea. The study demonstrates the unique capability of high-resolution, convection-permitting analyses to capture complex processes in orographically challenging regions and contributes to clarifying the seemingly contradictory trend of rising daily precipitation extremes despite falling annual precipitation totals in Southern Europe.