Development of climate indices relevant for agriculture in Africa under different climate change scenarios based on GCM and RCM ensembles

Abstract Africa is facing significant changes in different aspects of life caused by climate change. Our study analyses the temporal and spatial changes of several thermal, hygric, and agricultural indices in Africa and eleven subregions. The agricultural indices strongly depend on the rainy season’s onset and crop specific parameters for which maize acts as an example crop. We use ensembles of General Circulation Models (GCM_ens) from Coupled Model Intercomparison Project and Regional Climate Models (RCM_ens) driven by the respective GCMs within Coordinated Regional Downscaling Experiment-Coordinated Output for Regional Evaluation under the representative concentration pathways 2.6 (rcp26) and 8.5 (rcp85) until the end of the century. The results show complex changes in precipitation-related indices depending on the subregion, model family, scenario, and period. Focusing on the far-future (2071–2100), RCM_ens rcp85 simulates the largest changes compared to rcp26 and both GCM ensembles for most precipitation indices. A later onset of the first rainy season is depicted for most subregions. Regarding heat and drought, all indices project a strong change toward hotter and drier conditions for all subregions and models with large discrepancies between the emission scenarios. Combining both precipitation and temperature changes and further being sensitive to the temporal occurrence within a year, the used agricultural indices show mixed signals. However, most subregions are going to face an increasing crop water need but no clear trend of irrigation requirement or water availability as exemplified for maize. Overall, the RCMs project larger future climate changes than the GCMs under rcp85.