Discussion Paper The land biosphere, atmospheric chemistry and climate are inextricably interconnected. We describe the Yale Interactive terrestrial Biosphere (YIBs) model, a land carbon cycle model that has been developed for coupling to the NASA Goddard In5 stitute for Space Studies (GISS) ModelE2 global chemistry–climate model. The YIBs model adapts routines from the mature TRIFFID and CASA models to simulate interac-