Population exposed to compound extreme hot & humid and wet & windy events in Africa

Abstract Changes in compound extreme events are a hallmark of global warming, posing significant risks to human well-being. This study investigates projected changes in compound extreme hot & humid and wet & windy events across Africa by the end of the 21st century (2069–2098). Using the multi-model ensemble mean from the regional climate projections from the coordinated regional climate downscaling experiment-coordinated output for regional evaluations project, we examined both low/high representative concentration pathway (RCP2.6/8.5) emission scenarios. We estimated population exposure to these joint events by combining climate projections with low/high shared socioeconomic pathway (SSP1/SSP3) population growth scenarios. Broadly, changes are regionally-dependent. In some subregions, we found a substantial increase in the frequency and duration of compound extreme hot & humid events, rising by approximately 100%/600% under RCP2.6/RCP8.5, associated with a rise in extremely hot univariate events. Conversely, compound extreme wet & windy events are projected to weaken, particularly under RCP8.5, with reductions up to 64%, driven in most regions, by declines in extreme wet-only events. Global warming expands historical equatorial hotspots for heat events into eastern and southern Africa, which is less severe under RCP2.6. These changes significantly increase exposed populations to these hazards, affecting up to 668 million person-events across various IPCC reference subregions, especially in West, Central, Northeast, and Southeast Africa, as well as most of West and East South Africa, and Madagascar (MDG). In subregions like the Sahara and West Africa, population growth is the primary driver of exposure to hot & humid events, while in Central, North-East, South-East, West-South, East-South and MDG, climate and interaction effects are more influential. We stress the need to enhance climate adaptation policies, especially in West, Central, Northeast, Southeast Africa and MDG, to address these risks, as they could exacerbate climate refugee migration, heat-related illnesses, food insecurity, and societal instability. We also advocate for disseminating climate services, particularly in low-income countries, to support research for sustainable development.