Attribution of the 2025 Mediterranean Marine Heatwave to Climate Change Using Analogues

Abstract. The Mediterranean Sea experienced a record-breaking marine heatwave in 2025, raising questions about the influence of human-induced climate change. Using an analogue-based attribution approach, we compared historical sea surface temperature (SST) patterns from ERA5 reanalysis (1950–2024) to those observed during the event. By identifying the most similar SST anomaly patterns in a past period (1950–1986) and a more recent one (1987–2024), we assessed changes in SST and related atmospheric variables. We find that, under present-day climate conditions, analogous patterns result in significantly higher SST anomalies and stronger atmospheric responses – such as warmer near-surface air temperatures and intensified radiative fluxes – compared to the past. Statistical tests confirm that long-term warming trend has amplified Mediterranean SST extremes by up to 1.5 °C and associated heat exchange processes, though shifts in large-scale natural climate variability may also influence these outcomes, complicating attribution. Nonetheless, the dominant contribution to the 2025 marine heatwave severity is attributable to anthropogenic forcing. This study proves the effectiveness of the analogue method for assessing extreme events, also including marine heatwaves, in a warming Mediterranean context.