Historical and Projected Changes in Temperature–Precipitation Compound Hot and Dry Extremes across Africa Based on CMIP5 and CMIP6 Ensemble Simulations

Abstract. Compound climate extremes pose disproportionate risks to societies and ecosystems, yet their evolution across Africa remains poorly constrained. Here we present the first continent-wide, multi-generation assessment of historical and projected temperature–precipitation compound hot–dry extremes across Africa using CMIP5 and CMIP6 multi-model ensembles under the full range of emission scenarios. Observations indicate continent-wide warming of 0.21 °C decade-1; during 1980–2020, accompanied by spatially heterogeneous precipitation trends, establishing a baseline of increasing compound vulnerability. Despite projected increases in precipitation over much of tropical Africa, both CMIP5 and CMIP6 consistently project strong intensification of compound hot–dry extremes, driven primarily by accelerated warming. By mid-century (2035–2065), compound hot–dry frequency increases across all regions, with southern Africa experiencing 0.33–0.43 hot–dry months yr^-1; in CMIP6. By end-century (2070–2100), frequencies in western and eastern southern Africa reach 0.36–0.62 months yr^-1; under high-emission scenarios, representing more than a doubling relative to low-emission pathways. Compound event severity intensifies nonlinearly: cumulative event magnitude exceeds 10–13 σ in southern Africa and Madagascar, while mean event duration lengthens from ∼1–1.5 months historically to 4–6 months under high emissions. CMIP6 systematically projects stronger increases in compound frequency, magnitude, and duration than CMIP5, reflecting enhanced land–atmosphere coupling and higher climate sensitivity. Although strong mitigation substantially limits these increases, compound hot–dry extremes intensify even under low-emission pathways. These results demonstrate that compound climate risk may escalate regardless of mean precipitation trends, underscoring the urgency of compound-aware adaptation strategies and the substantial mitigation benefits of limiting future climate impacts.