The context-dependent role of greenspaces and environmental performance in ensuring human well-being under urban heat islands in Africa

Urban heat islands (UHI) are an increasing concern in rapidly urbanizing regions, yet their prevalence and consequences across African cities remain poorly understood. Here, we assess the extent of UHI across all African cities and examine how vegetation influences urban heat and human well-being. To get this done, we collected multiple variables across 1010 cities across Africa and analyzed them using varied statistical methods. We first show that nighttime land surface temperatures are significantly higher within cities than outside cities, matching evidence of UHI in approximately 63% of all cities. Also, urban areas exhibit significantly lower vegetation cover (greenspaces), measured using the enhanced vegetation index (EVI), suggesting that vegetation loss might contribute to elevated urban temperatures. However, using a linear mixed-effects model, we found that vegetation does not uniformly reduce UHI intensity across cities. Instead, higher EVI is associated with significantly stronger reductions in UHI intensity only in coastal and inland capital cities, while no significant vegetation effect is observed in inland cities. We then evaluated how urban heat, vegetation, and environmental conditions jointly influence human well-being, measured using life satisfaction, the UNDP Health Index, and the Human Development Index (HDI). We found that urban heat consistently reduces well-being, whereas environmental performance generally promotes it, but in a context-dependent manner. Specifically, EVI and biomass interact to buffer negative effects and enhance positive effects, particularly when combined with high environmental performance. Furthermore, significant higher-order interactions revealed that human wellbeing is shaped by complex ecological-environmental interactions rather than by single predictors alone. Together, our findings highlight the importance of urban greenspaces in moderating heat exposure and shaping well-being in African cities, while emphasizing that these effects operate through complex interactions among urban, ecological, and environmental systems.