Complexity of hydroclimatic changes in the Mediterranean: Exploring climate drivers using ERA5 reanalysis

The Mediterranean region has experienced pronounced hydroclimatic variability over recent decades, motivating a closer examination of the physical processes underlying these changes. This study analyzes ERA5 reanalysis data for 1950–2024 to investigate long-term trends and interrelations among temperature, precipitation, evaporation, wind, sensible heat, and column water, distinguishing between land and sea domains and multiple atmospheric layers. Results show a strong warming signal in the lower troposphere, with temperatures increasing by 0.03 °C year−1 over land and 0.015 °C year−1 over sea, and near-stagnancy in the upper troposphere, which indicates a steepening lapse rate. Unlike temperature, evaporation shows no strong long-term increase: over sea, it rises only slightly, and over land, it declines modestly, with both weak tendencies dominated by strong interannual variability and consistent with declining winds. Over land, sensible heat flux increases, while over the sea, it decreases, revealing divergent energy-partition regimes. Precipitation exhibits no significant long-term change, suggesting that the atmosphere has become warmer and slightly moister but less effective in converting vapor into rainfall. Correlation analyses indicate that wind speed exerts a stronger control on evaporation and precipitation than temperature across the whole region. The Hurst–Kolmogorov stochastic framework further reveals persistent long-term variability in Mediterranean hydroclimatic processes, underscoring that the region’s climate behavior is shaped by dynamic and complex interactions rather than by temperature trends alone.