Impacts of climate change on crop production in West Africa: A modeling approach using Aquacrop and remotely sensed data.

Climate-crop relationships can be explained with crop yield models. In this study, we used a crop model (Aquacrop) developed by the Food and Agricultural Organization (FAO) to simulate maize, millet, and rice yields from 2002 to 2018 for nine West African countries (Benin, Burkina-Faso, Côte d'Ivoire, Ghana, Mali, Niger, Nigeria, Senegal, Togo). We ran the model for Benin (pilot country) and used the calibrated parameters for simulations over the remaining countries. The model was said to be satisfactory at a Pearson correlation greater than 0.35. For any correlation below that benchmark, the model was said to be unsatisfactory. Seasonal (March-August) climate data derived from remote sensing (MODIS, temperature) and regional analysis (MERRA-2, precipitation) were used as climate inputs for the model. We found that the model's performance was best for millet, relative to maize, and rice. Additionally, the potentialities of this model were extended using projected temperature and precipitation to understand the impacts of these variables on nation-level yield, in the context of a changing climate. We examined the future changes in decadal yield for maize, millet, and rice from 2030 to 2080, and used the previously calibrated model to conduct future yield simulations based on seasonal temperature and precipitation projections derived from the Coordinated Regional Downscaling Experiment (CORDEX). We considered four representative concentration pathways (2.6, 4.5, 6.0 and 8.5). Simulation results indicated that under projected climate scenarios, future yields of maize, millet and rice crops will decrease (per unit area). The use of additional parameters such as irrigation scheme, soil fertility, and management strategies could increase the model performance. Overall, future temperature and precipitation might significantly impact maize, millet and rice yield in west Africa.