The AgMIP Coordinated Climate-Crop Modeling Project (C3MP): Methods and protocols.

Climate change is expected to alter a multitude of factors important to agricultural systems. Changes to carbon dioxide concentrations ([CO2]), temperature and water (CTW) will be the primary drivers of climate change in crop growth and agricultural systems. Therefore, establishing the CTW-chnage sensitivity of crop yields is an urgent research need and warrants diverse methods of investigation. Crop models provide a biophysical, process-based tool to investigate crop responses across varying enviromental conditions and farm management techniques, and have been applied in climate change assessment by using a variety of methods. However, there is a significant amount of divergence between various crop models' responses to CTW changes. While the application of a site-based crop model is relatively simple, the coordination of such agricultural impact assessments on larger scales requires consistent and timely contributions from a large number of crop modelers, each time a new global climate model (GCM) scenario or downscaling technique is created. A coordinated, global effort to rapidly examine CTW sensitivity across multiple crops, crop models, and sites is needed to aid model development and enhance the assessment of climate impacts. To fulfill this need, the Coordinated Climate-Crop Modeling Project (C3MP) was initiated within the Agricultural Model Intercomparison and Improvement Project (AgMIP). The submitted results from C3MP Phase I are currently being analyzed. This chapter serves to present and update the C3MP protocols, discuss the initial participation and general findings, comment on needed adjustments, and describe continued and future development.