Modelling impacts of climate change on coastal West African rainfall

Abstract

Several tropical regions of the world, including West Africa are strong climatic hotspots where the increase in extreme climatic events (e.g., droughts) impacts on water resources and hydroecological systems. Even though the West African Sahel has been widely studied, reports on the rainfall climatology of coastal West Africa are considerably limited. Assessing the evolutionary changes in rainfall in this region is crucial to improving understanding on the impacts of global climate systems on rainfall variability. The main aim of this study is to assess the impact of climate change on the characteristics (mean annual, wettest month, driest month, and mean monthly) of coastal West African rainfall using General Circulation Model and two representative concentration pathways (RCP 4.5 and RCP 8.5 emission scenarios).Climate teleconnection induced rainfall is quantified using the partial least squares regression, and the dominant patterns of rainfall variability in the region are also assessed. The results indicate that areas along the coast with leading modes of rainfall variability and characterized by bimodal rainfall patterns are projected to receive highest rainfall in the mid and end of the century. However, inland areas are expected to receive low rainfall under the influence of both emission scenarios. An exception to this is the inland middle belt in Nigeria, which is projected to receive more rainfall than its surrounding areas. These results imply an intensification of the water cycle along the coastal region that could lead to increasing propensity of flood and drought events. Finally, Togo, Côte d'Ivoire, southern Ghana, Benin are hotspots in coastal West Africa where climate teleconnection patterns induce changes in rainfall.