Potential shift of rainy seasons’ onset and cessation under climate change scenarios in West Africa

Information on the onset and cessation of rainy seasons is an important prerequisite for planning the sowing of crops in West Africa. A late onset, but also too early cessation of a rainy season, has a direct impact on plant growth and thus on the crop yield in the region. However, onset and cessation dates of rainy seasons can change under future climatic conditions. Therefore, this information is key for stakeholders and decision-makers to mainstream climate change into agricultural activities and policies for better adaptation in the region.

To obtain information on the onset and cessation of rainy seasons on a regional scale under future climate change, Regional Climate Models (RCMs) are applied to dynamically downscale global climate projections generated by Earth System Models (ESMs). Therefore, regional climate projections provide more detailed information due to the higher spatial resolution compared to the climate projections generated by ESMs.

The study will show initial results on the onset and cessation of rainy seasons in West Africa under two emission scenarios using the Representative Concentration Pathways (RCPs) 2.6 and 8.5 for the end of the century (2071-2100 vs. 1981-2010). The regional climate projections are taken from the Coordinated Output for Regional Evaluations (CORE) embedded in the WCRP Coordinated Regional Climate Downscaling Experiment (CORDEX) for Africa with a spatial resolution of about 25 km. In this initiative, three different RCMs (REMO2015, RegCM4-7, and CCLM5-0-15) were applied to perform the downscaling process.