There is no doubt that Earth is warming due to our emissions of greenhouse gases. However, our understanding of how climate is changing at the regional level is much poorer. For example, over most of the globe there is little agreement amongst contemporary climate models as to whether precipitation will increase or decrease for a particular location. And yet such knowledge is vital for a number of reasons – not least climate adaptation. In this talk I will argue that we need a much more internationally coordinated and funded approach to develop a new generation of climate and impact assessment models – a “CERN for Climate Change”.