We present the first-ever global simulation of the full Earth system at 1.25 km grid spacing, achieving highest time compression with an unseen number of degrees of freedom. Our model captures the flow of energy, water, and carbon through key components of the Earth system: atmosphere, ocean, and land. To achieve this landmark simulation, we harness the power of 8192 GPUs on Alps and 20480 GPUs on JUPITER, two of the world’s largest GH200 superchip installations. We use both the Grace CPUs and Hopper GPUs by carefully balancing Earth’s components in a heterogeneous setup and optimizing acceleration techniques available in ICON’s codebase. We show how separation of concerns can reduce the code complexity by half while increasing performance and portability. Our achieved time compression of 145.7 simulated days per day enables long studies including full interactions in the Earth system and even outperforms earlier atmosphere-only simulations at a similar resolution.

Summary We present a methodology to enable the complete software development life cycle on Cray XC systems within a container that can hold any version of the Cray Programming Environment (CPE). The installation of the CPE inside a container facilitates many aspects of the typical HPC support and operation workloads of managing Cray XC systems such as testing new CPEs, comparing CPE performances, or keeping software built with an old CPE running on updated systems. The procedure for creating a container with a CPE inside consists of three steps: the creation of a container holding the targeted CPE, the compilation of the desired software within such containers, and the packaging of the resulting binaries, libraries, and dependencies within a second lightweight container. We showcase the methodology by fulfilling a user requirement of running a two‐year‐old version of the COSMO model built with an old CPE 16.11 on today's system.