Contrasting consequences of the Great Green Wall: Easing aridity while increasing heat extremes

The Great Green Wall (GGW) is a multibillion-dollar African initiative to combat desertification in the Sahel. However, the potential climate impacts of the most recent GGW plan on northern Africa have not yet been adequately evaluated, raising concerns about unforeseen climate ramifications that could affect stability in northern Africa and undermine the goals of the initiative. Using a high-resolution (∼13 km) regional climate model, we evaluate the climate impacts of four GGW scenarios with varying vegetation densities under two extreme emission pathways (low and high). Higher vegetation density GGW scenarios under both emission pathways show enhanced rainfall, reduced drought lengths, and decreased summer temperatures beyond the GGW region relative to the cases with no GGW. However, all GGW scenarios show more extreme hot days and higher heat indices in the pre-monsoonal season. These findings highlight the GGW contrasting climatic effects, emphasizing the need for comprehensive assessments in shaping future policies.