What is the UK-Japan Climate Collaboration ? The aim of the UJCC project is to exploit the power of the Earth Simulator to produce world-leading climate simulations. The enhanced resolution models will allow unprecedented fidelity of simulation, and allow many emergent phenomena to be resolved. The science of the project will then be to understand how the increased resolution changes the large scale mean climate, consider whether the emergent processes are therefore essential to produce reliable climate models, and consider if these processes can be parameterized in lower resolution models, or if their importance is enough to drive model resolution to increase.