Effective adaptation to climate change requires detailed, tangible information about its impacts. This paper presents a novel simulation framework that combines storyline approaches based on spectral nudging with emerging kilometre-scale global climate modelling capabilities using the IFS-FESOM model. This approach allows for reconstructing recent extreme events and their potential evolution under different climate conditions while maintaining high-resolution local details. We demonstrate the system’s ability to reproduce observed variability on daily and longer timescales during the 2017–2023 period, particularly in the extratropics, and evaluate its performance using high-quality observations, including data from the MOSAiC expedition. To showcase the potential of this framework, we focus on two recent extreme events in Europe: the July 2019 heatwave and the July 2021 Ahrtal flooding. These examples highlight how kilometre-scale simulations can provide more granular, localized insights into climate change impacts, improving risk assessment and adaptation planning. This work, conducted as part of the European Union’s Destination Earth initiative, demonstrates how global, high-resolution simulations can be harnessed to support the development of digital twins of the Earth system, advancing both climate science and practical decision-making.

The impact of climate change on the intensity of mid-latitude cold air outbreaks is a debated topic due to uncertainty associated with internal atmospheric dynamics. Here, we employ an event-based storyline approach in which the evolution of the large-scale atmospheric circulation is nudged to reanalysis data at different global warming levels based on historical and high-emission scenario simulations. We thereby quantify the thermodynamic climate-change effects of pre-industrial, 2ºC and 4ºC warmer climates compared to present-day climate for three cold surges in East Asia during the winter 2020/21. The strongest warming occurs over northeast Asia, reaching up to +12ºC in a +4ºC warmer climate and caused by the advection of less cold air from winter ice-free regions in the Arctic, where the change of surface air temperature exceeds +20ºC. In contrast, over southern China, a moderate cooling is present from pre-industrial to present-day climates, due to the observed and expected increase in aerosol concentration, which peaks by the mid-21st century and alters the radiative balances. This cooling effect is likely to persist well into a +2ºC-warmer climate; however, it may become undetectable at the end of the 21st century (+4ºC warming). In summary, our findings underscore the important thermodynamic impact associated with Arctic amplification and cooling effect of aerosol-induced changes in the radiation budget on East Asian cold extremes.

Extreme weather events are triggered by atmospheric circulation patterns and shaped by slower components, including soil moisture and sea-surface temperature, and by the background climate. This separation of factors is exploited by the storyline approach where an atmosphere model is nudged toward the observed dynamics using different climate boundary conditions to explore their influence. The storyline approach disregards rather uncertain climatic changes in the frequency and intensity of dynamical conditions, but focuses on the thermodynamic influence of climate on extreme events. Here we demonstrate an advanced storyline approach that employs a coupled climate model (AWI-CM-1-1-MR) where the large-scale free-troposphere dynamics are nudged toward ERA5 data. Five-member ensembles are run for present-day (2017–2019), pre-industrial, +2K, and +4K climates branching off from CMIP6 historical and scenario simulations of the same model. In contrast to previous studies, which employed atmosphere-only models, feedbacks between extreme events and the ocean and sea-ice state, and the dependence of such feedbacks on the climate, are consistently simulated. Our setup is capable of reproducing observed anomalies of relevant unconstrained parameters, including near-surface temperature, cloud cover, soil moisture, sea-surface temperature, and sea-ice concentration. Focusing on the July 2019 European heatwave, we find that the strongest warming amplification expands from southern to central Europe over the course of the 21st century. The warming reaches up to 10 K in the 4K warmer climate, suggesting that an analogous event would entail peak temperatures around 50 ºC in central Europe.