Intensifying human-driven heatwaves characteristics and heat related mortality over Africa

Heatwaves in Africa are expected to increase in frequency, magnitude, and duration. This is significant because the health burden is only expected to worsen as heatwaves intensify. Inadequate knowledge of the climate's impact on health in developing nations such as Africa makes safeguarding the health of vulnerable groups at risk challenging. In this study we quantify possible role of human activity in heatwave intensification during the historical period, and project the future risk of heat-related mortality in Africa under two representative Concentration Pathways (RCP26) and (RCP60). Heatwaves are measured using the Excess Heat Factor (EHF); the daily minimum (Tn) and maximum (Tx) are used to compute the EHF index; by averaging the day's Tx and Tn. Two heat factors, significance (EHIsig) and acclimatization (EHIaccl) are combined in the EHF to quantify the total excess heat. Our results confirm that the recent intensification of heatwaves over Africa during the historical period is attributable atmospheric greenhouse gas forcing and changes in land use. The Return event highlights the potential future escalation of heatwave conditions brought on by climate change and socioeconomic variables. RCP26 indicates a substantial rise in heat-related mortality, with an increase from about 9,000 deaths per year in the historical period to approximately 23,000 deaths per year at the end of the 21st century. Similarly, the RCP60 showed an even more significant increase, with heat-related deaths increasing to about 43,000 annually. This study highlights the potentially growing risk of intensifying heatwaves in Africa under different emission scenarios. It projects a significant increase in heatwave magnitude, duration, frequency, and heat-related mortality. Africa's low adaptive capacity will amplify the impact, emphasizing the need for emissions reduction and effective adaptation measures.