Economic efficiency and targeting of the African Great Green Wall

Land degradation in the Sahel threatens livelihoods and food security. The Great Green Wall programme is a colossal initiative to restore 100 million hectares of degraded ecosystems across 11 countries in the region, which started in 2007 to also promote sustainable development and climate change mitigation. We evaluated the economic costs and benefits of future land restoration projects under this programme. We applied different scenarios that account for both market-priced and non-market benefits from restored ecosystems and consider the heterogeneity of local decision-making contexts in terms of investment planning horizons, discount rates, and the time needed for the restored ecosystems to start yielding their benefits in full. The results show that every US dollar invested into land restoration yields on average US$1.2 under the base scenario, ranging from US$1.1 to US$4.4 across the scenarios. At most, ten years are needed for land restoration activities to break even from the social perspective, accounting for both market-priced and non-market ecosystem benefits. To fund all proposed land restoration activities, an investment of US$44 billion is needed under the base scenario (US$18–70 billion across scenarios). Violent conflicts in the Sahel are estimated to reduce the accessibility to these degraded ecosystems from 27.9 million hectares to 14.1 million hectares. The study highlights activities and locations where land restoration is both economically attractive and ecologically sustainable, even after accounting for lower survival rates of planted trees and grasses, persistence of land degradation drivers and the growing number of violent conflicts hindering land restoration in the Sahel. This information can help improve the targeting of future land restoration activities in the region.