Attribution of the record-breaking June 2024 Eastern Mediterranean heatwave: Contrasting roles of soil moisture in anthropogenic forcing and natural variability

In June 2024, the Eastern Mediterranean experienced an unprecedented heatwave, with regional mean temperature exceeding the climatological average by more than 3 °C, the highest since 1960. However, the relative contributions of anthropogenic forcing and natural variability, as well as the respective roles of atmospheric circulation and soil moisture to this event, have remained unclear. Based on ERA5 reanalysis and HadGEM3-A-N216 attribution simulations, we estimate that anthropogenic forcing accounted for roughly half of the observed temperature anomalies. Human activities not only directly increased surface warming through greenhouse gas emissions but also reduced soil moisture, which in turn amplified temperature anomalies via land-atmosphere coupling. Using the flow analogue and circulation projection methods, we find that another half of warming anomalies attributable to natural variability is dominated by atmospheric circulation change, which features an anomalous anticyclone driven by an upstream wave train and sustained by warm North Atlantic SST anomalies. Additionally, in the component of natural variability, we found a thermodynamic cooling contribution from the wetting soil moisture anomalies, which is likely associated with above-normal preceding precipitation, indicating that wetting soil related land-atmosphere coupling slightly offset the circulation-induced warming in this heatwave. The results highlight contrasting roles of soil moisture in anthropogenic forcing and natural variability in the climate change hotspot, providing new physical insights into future extreme heatwave events.