The Destination Earth digital twin for climate change adaptation

Abstract. The Climate Change Adaptation Digital Twin (Climate DT), developed as part of the European Commission’s Destination Earth (DestinE) initiative, is a pioneering effort to build an operational climate information system in support of adaptation. This system produces global climate simulations with local granularity, providing information at scales that matter for decision-making. The Climate DT delivers multi-decadal climate simulations at spatial resolutions of 5–10 km, with hourly outputs, offering globally consistent, frequently updated data. The km-scale simulations address some limitations of current climate models, improving local granularity and reducing longstanding biases, supporting more equitable (understood as accessible and relevant across regions) and credible climate information. The Climate DT is built on cutting-edge infrastructure, expert collaboration, and digital innovation. It supports real-time, on-demand responses to policy questions, with quantified uncertainty. It fosters interactivity by allowing users to influence simulation design, model outputs, and applications through co-design. AI-based tools, including emulators and chatbots, are being developed to enhance flexible scenario exploration and ease climate information access. Sector-specific applications are embedded in the system to generate tailored climate-impact indicators, with examples for energy, water, and forest management. The applications have been co-designed with informed users. An important innovation is the use of high-resolution storylines. These are physically consistent simulations of extreme events under different climate conditions that provide contextual insights to support concrete adaptation decisions. A unified workflow across platforms orchestrates all components ensuring automation, containerisation for portability, and traceability. The unified data management ensures consistency and eases the usability of the data. Data is delivered using standard grids (HEALPix) at high-frequency (hourly) and follows a strict governance policy. Streaming enables real-time data use and unlocks access to the unprecedented data produced by the high- resolution simulations. Monitoring tools provide real-time quality control of both data and models and provide diagnostics during the Climate DT operation. The compute-intensive system is powered by world-class supercomputing capabilities through a strategic partnership with the European High Performance Computing Joint Undertaking (EuroHPC). Despite high computational demands, the Climate DT sets a new benchmark for delivering equitable, credible, and actionable climate information. In this way it complements existing initiatives like CMIP, CORDEX, and national and European climate services, and aligns with global climate science goals for climate adaptation.