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.
@article{arxiv.2511.02021,
title = {Computing the Full Earth System at 1 km Resolution},
author = {Daniel Klocke and Claudia Frauen and Jan Frederik Engels and Dmitry Alexeev and René Redler and Reiner Schnur and Helmuth Haak and Luis Kornblueh and Nils Brüggemann and Fatemeh Chegini and Manoel Römmer and Lars Hoffmann and Sabine Griessbach and Mathis Bode and Jonathan Coles and Miguel Gila and William Sawyer and Alexandru Calotoiu and Yakup Budanaz and Pratyai Mazumder and Marcin Copik and Benjamin Weber and Andreas Herten and Hendryk Bockelmann and Torsten Hoefler and Cathy Hohenegger and Bjorn Stevens},
journal= {arXiv preprint arXiv:2511.02021},
year = {2025}
}