Next generation earth system modelling for realistic projections of rapid climate evolution in the coming decades

RealESM will enhance our ability to anticipate global and regional climate conditions and extreme events in the coming years and decades, by realistically and efficiently simulating atmospheric and ocean processes, and their interactions, under anthropogenic and natural forcing. For realistic projections of the current rapid climate evolution, and effective communication of the physical hazards and socioeconomic consequences, a novel, integrated approach is needed, optimally combining traditional climate models and AI tools, alongside efficient analysis methods that deliver the benefits of high-resolution state-of-the-art modelling whilst moderating CPU and storage costs. RealESM delivers (i) advances in process representation in Earth System Models at varying resolutions, (ii) step changes in capabilities to efficiently simulate and project global and regional climate change on decadal scales, (iii) detailed quantification of physical hazards in the atmosphere and ocean, and the role of atmosphere-ocean interactions in their development, and (iv) science-based communication of a broader set of possible climate outcomes for the coming decades, in support of adaptation and risk reduction planning.We give particular focus to Earth System components undergoing rapid change, such as anthropogenic and natural emissions of aerosols, and complex interactions and physical processes known to be sensitive to spatial resolution, such as marine heatwaves and jet and tropical cyclones, and their links to regional extreme precipitation. Building on advances in Earth System modelling and novel techniques, RealESM will enable the climate science community to efficiently and comprehensively simulate the broader climate evolution possible over the coming decades, including high-impact but realistic climate and weather conditions brought about by the interactions of emissions changes, atmospheric and oceanic processes, and internal variations in the climate system.