The Decapodes.jl framework offers a domain-specific language for specifying systems of multiphysics equations, and formally composes such complex systems via undirected wiring diagrams. Since equations are encoded in the Discrete Exterior Calculus (DEC), these composed Decapodes can be compiled, automatically generating performant simulation code. Composition of Decapode diagrams along physical quantities manages the complexity that arises when bringing together multiphysics systems in a climate modeling context. In this talk, we briefly cover the Decapodes.jl framework and three example problems: the Halfar glacial model, the Halfar model’s composition with the Budyko-Sellers energy balance model, and the Klausmeier vegetation model.