Climate Change and the Dominant Influence of Record North Atlantic Heat on the 2026 Eastern Mediterranean Winter Anomalies

Abstract

Winter climate variability across the Northern Hemisphere has frequently been associated with Arctic amplification and high-latitude atmospheric forcing. However, the winter of 2026 in the Eastern Mediterranean (EM) exhibited anomalous atmospheric conditions that could not be clearly explained by Arctic-driven mechanisms alone. This study investigates the role of North Atlantic sea surface temperature (NASST) anomalies as a dominant forcing mechanism underlying the region’s unusual winter climate. Using ERA5 reanalysis data (the fifth-generation reanalysis dataset from the European Centre for Medium-Range Weather Forecasts, ECMWF) in combination with satellite-derived NASST observations, a pronounced and persistent warm anomaly was identified over the North Atlantic during the winter season, persisting throughout the season period. These anomalous oceanic conditions were associated with significant modifications in large-scale atmospheric circulation patterns, potentially influencing temperature and precipitation variability across the Eastern Mediterranean region. The analysis demonstrates that the Atlantic “warm patch” substantially altered large-scale atmospheric circulation, generating a pattern analogous to the positive phase of the North Atlantic Oscillation (NAO). This circulation anomaly induced a quasi-stationary Rossby wave train that propagated toward the Mediterranean basin, leading to pronounced anomalies in regional temperature, precipitation, and cyclone activity. Comparative diagnostics further revealed that the spatial and temporal evolution of North Atlantic sea surface temperature (SST) anomalies exhibited a stronger correspondence with Mediterranean atmospheric variability than did concurrent Arctic signals. In particular, the persistence and intensity of the Atlantic SST anomalies appeared to reinforce atmospheric teleconnection pathways linking the North Atlantic and Eastern Mediterranean regions. Although Arctic processes may have contributed secondary effects, the overall evidence indicates that North Atlantic forcing represented the dominant driver of the Eastern Mediterranean’s atypical winter conditions during 2026. These findings emphasize the critical role of ocean-atmosphere coupling within the North Atlantic sector and highlight the predictive value of monitoring Atlantic SST anomalies for improving seasonal climate forecasting and regional climate risk assessments in the Mediterranean basin.