Using global spectrally nudged storylines to attribute anthropogenic amplification of the 2024 Valencia DANA extreme precipitation event

In late October 2024, the western Mediterranean experienced an extreme precipitation event centred over Valencia (southeastern Spain), producing record-breaking rainfall, flash floods, and severe societal impacts. The event was associated with a quasi-stationary cut-off low (COL; DANA in Spanish), which favoured sustained deep convection through strong instability, abundant moisture supply, and interaction with regional orography.

The COL organised an atmospheric-river-like moisture transport from northwestern Africa, while additional moisture was supplied by the anomalously warm Mediterranean Sea. To assess the role of anthropogenic climate change in amplifying this event, we apply a storyline-based event attribution framework using high-resolution (∼9 km) simulations from the European Union’s Destination Earth initiative. An ensemble of simulations is performed with the coupled IFS-FESOM model, spectrally nudged to ERA5 to constrain large-scale circulation, and compares two climate states: a Counterfactual (~1950) and a Factual (present-day) climate. This approach isolates thermodynamic effects while preserving the observed synoptic evolution.

Results show that the synoptic configuration alone was sufficient to generate extreme rainfall; however, human-induced warming substantially intensified the event. In the Factual scenario, atmospheric moisture content and horizontal moisture transport increased by 18–24%, convective instability (CAPE) increased by ~25%, and sea surface temperatures in the western Mediterranean were ~2°C warmer, enhancing evaporation. As a result, total precipitation over Valencia increased by ~20%, whereas peak precipitation rates on 29 October were ~36% higher, exceeding the Clausius-Clapeyron scaling implied by the mean warming across scenarios.

These findings, which agree with those obtained by independent researchers using alternative methods, demonstrate that anthropogenic warming significantly amplified the intensity of this Mediterranean extreme precipitation event through thermodynamic mechanisms, even without changes in large-scale circulation. High-resolution, physically consistent storyline simulations provide a robust framework for quantifying the contributions of climate change to individual high-impact events, thereby supporting impact-relevant attribution in vulnerable coastal regions.