Disentangling drivers of compound heat and drought in Europe

Future projections suggest that compound heat and drought in Europe will occur more frequently under increasing global warming. Year-to-year variability driven by atmospheric circulation patterns and decadal phenomena like the Atlantic Multidecadal Variability (AMV) temporarily dampens or amplifies these changes. As such, the frequency and intensity of these events can be affected by anthropogenic and natural drivers.
Disentangling these contributions is essential for understanding current events and the reliability of future projections, as well as for improving long-term predictions of such events and refining risk assessments. Although recent attribution studies have started to address the impact of natural climate variability, these studies are often limited to heat waves and do not explore other high-impact phenomena. Further, they are often based on observational data exclusively and therefore lack the sampling of internal variability that is required for a robust assessment. To address these gaps, we present a comprehensive analysis that quantifies the dynamical and thermodynamical contributions of not only global warming, but also considers internal climate variability using conditional attribution with atmospheric flow analogues. We use the CMIP6 version of the MPI Grand Ensemble (MPI-GE6) single-forcing (30 member) and historical (50 member) experiments to identify analogues based on real events from ERA5. This approach enables a clear separation and quantification of dynamical and thermodynamic contributions and how these change under different global warming states and under different forcing configurations, helping to better distinguish how both anthropogenic and natural factors influence high-impact heat and drought events in Europe.