Biocrusts are photosynthetic communities on the surface of many desert soils. We investigated the response of biocrusts and the soil beneath them (including plant roots) to 9 years of simulated warming and changing precipitation patterns. We monitored the exchange of carbon between soil and atmosphere using automated chambers. As plants and biocrusts responded negatively to the treatments, we saw reduced photosynthesis in biocrusts but variable overall carbon exchange over 9 years.