Projected Impact of Increased Global Warming on Heat Stress and Exposed Population Over Africa

This study investigates the impact of increased global warming on heat stress changes and the potential number of people exposed to heat risks over Africa. For this purpose a heat index has been computed based on an ensemble-mean of high-resolution regional climate model simulations from the Coordinated Output for Regional Evaluations embedded in the COordinated Regional Climate Downscaling EXperiment, under two Representative Concentration Pathways (RCPs) scenarios (RCP2.6 and RCP8.5), combined with projections of population growth developed based on the Shared Socioeconomic Pathways (SSPs) scenarios (SSP1 and SSP5). Results show that by the late 21st century, the increased global warming is expected to induce a 12-fold increase in the area extent affected by heat stress of high-risk level. This would result in an increase of about 10%-30% in the number of days with high-risk heat conditions, as well as about 6%-20% in their magnitude throughout the seasonal cycle over West, Central, and North-East Africa. Therefore, and because of the lack of adaptation and mitigation policies, the exacerbation of ambient heat conditions could contribute to the exposure of about 2-8.5 million person-events to heat stress of high-risk level over Burkina Faso, Ghana, Niger, and Nigeria. Furthermore, it was found that the interaction effect between the climate change and population growth seems to be the most dominant in explaining the total changes in exposure due to moderate and high heat-related risks over all subregions of the African continent.