Abstract
<title>Abstract</title> <p>The Great Green Wall aims to improve livelihoods and combat climate change across the Sahel. But interactions between greening and humid-heat have not been assessed. By harmonizing high-resolution climate data with vegetation and demographic datasets, we show that between 1983–2016 hazardous humid-heat days (HHD) in greening areas increased by 1.7-fold and 2.6-fold compared to areas with no vegetation change and decreasing vegetation, respectively. Amplified HHD intensity was more associated with elevated atmospheric moisture than air temperatures. In these areas, 45 million people (47% children) were exposed to >30 HHD in 2016. By 2050, nearly all Sahelian residents may experience >60 HHD per year. Our findings suggest that moisture may drive greening and elevate humid-heat risks, underscoring the need for adaptations that factor in humid-heat.</p>