To fully understand climate change – its causes and consequences – you need a grasp of many different fields of science. Bringing together multiple experts can be hard because researchers are increasingly specialized, don’t understand each other’s jargon, and aren’t encouraged to explore how their knowledge inter-relates. But in climate science, computational models overcome these barriers. Today’s climate models are assembled from many pieces, built by different research groups, each capturing a different aspect of the overall climate system. This isn’t easy – like a jigsaw puzzle where the pieces weren’t designed to fit together. But once the pieces are assembled, the models support a new kind of collaboration. They allow scientists from very different fields to combine their knowledge to answer big questions, and work together on shared experiments. In this chapter, we’ll explore this process of coupling climate models, find out why it’s so challenging, and meet another of our case studies, the Institut Pierre Simon Laplace (IPSL) in Paris, France.