The work of the Joint Lab ExaESM is conducted in two major scientific activities. The first activity is focusing on Exascale code scalability. It tries to achieve exascale readiness by improving scalability, facilitating portability and future-proofing, increasing resource and energy efficiency to enable ESM codes to run, simulations at higher resolution, and by resolving more processes. The Joint Lab activity can support this via fostering synergies, optimising community-wide developments, therefore preparing the HGF ESM community for the first European exascale machine to be located at the Jülich Supercomputing Centre.