Introduction of heat stress on global crop production in the Community Land Model (CLM5)

CLM5, the land model for the Community Earth System Model (CESM), simulates complex terrestrial processes and provides us with a global understanding of the interplay between energy, water and biochemistry fluxes. The crop representation in CLM5 currently lacks the inclusion of specific heat stress that can harm crop yield during crop sensitive stages. As heatwaves are becoming more frequent, we assess the potential of including specific heat-stress functions to target crop development in the working version of CLM5, the Community Terrestrial Systems Model version 5.2 (CTSM5.2). Several model implementations and parameterizations are assessed to target the leaf area index (LAI) or crop grain production directly and are compared to the default model version in terms of impact and to global annual yield data from the FAO in terms of model accuracy. Uncertainties and challenges in crop modelling and model development are also highlighted.