Regional and weather-type modulation of global warming–driven intensification of Italian precipitation extremes from multi-year storyline simulations

Extreme precipitation has recently caused substantial damage in Mediterranean countries, including Italy, but robustly attributing such regional extremes to climate change remains difficult due to the interplay between thermodynamic and atmospheric circulation changes. Event-storyline approaches, where the same meteorological events are simulated under different climate conditions, are increasingly used to isolate the thermodynamic impact. However, the potential of multi-year, spectrally-nudged storyline simulations to investigate statistical changes—rather than individual events—remains largely unexplored. Here, we exploit this potential using 2017–2024 data from the Destination Earth Digital Twin for Adaptation, demonstrating robust changes in the statistics of both mean and extreme precipitation over Italy and their implications for interpreting signals in individual extreme events. Results show that, despite fixed large-scale circulation, the number of wet days and annual mean precipitation decrease in southern Italy in summer, while annual mean precipitation increases slightly over northern Italy. In contrast, mean annual precipitation maxima increase nearly uniformly from north to south at rates close to 7% per degree of global-mean warming. Higher precipitation quantiles are more strongly amplified, with local maximum responses reaching up to 15–25C. Using weather-type composites of precipitation extremes, we find that these amplified responses are regional, seasonal, and circulation-dependent, and primarily associated with weather types (WTs) occurring in autumn and winter. These amplified responses are illustrated via four individual extreme precipitation events representative of the identified WTs: Storm Vaia of 2018, the Emilia-Romagna floods of 2023, the Marche flood of 2022, and a Pre-Alpine convective event of 2020. In these events, daily precipitation increases exceed local total-column water vapour scaling, implying super-Clausius–Clapeyron behaviour. Overall, our results demonstrate that, under identical synoptic forcing, anthropogenic global warming is already manifesting its impacts on Italian precipitation extremes, but the response is varied and cannot be reduced to a single scaling relationship.