The event is targeted at weather and climate modellers at all career stages. The participants will bring their own codes to the hackathon and work in teams, together with HPC experts, to improve the performance of their code. This will be the second of four ESiWACE3 hackathons, and the goal of this event is to assist climate scientists with optimising earth-system models (ESMs). More informationen: https://www.esiwace.eu/events/2nd-esiwace3-hackathon