Clustered land restoration projects increase cloud formation in West African drylands

Land restoration projects are increasingly implemented across Africa and other regions of the world to combat land degradation, and contribute to climate change mitigation efforts by storing anthropogenic carbon emissions in vegetation. However, increases in vegetation cover can directly impact local climate by altering surface properties, the exchange of water and energy between the Earth’s surface and atmosphere, and ultimatly cloud formation and precipitation. Although the influence of vegetation on the local climate is relatively well studied, it remains difficult to predict the local climate impacts of restoration. In West Africa, satellite observations have shown cloud enhancement over larger protected areas. However, even though different land restoration practices (e.g. farmer-managed natural regeneration, agroforestry or reforestation) result in different spatial patterns of vegetation, it remains unclear how these patterns affect cloud formation in this region.

To this end, we investigated how the extent and spatial arrangement of land restoration (in this case reforestation) influence cloud formation using the Weather Research and Forecasting (WRF-ARW v4.1.4) mesoscale atmospheric model. We focused on the transnational W-Arly-Pendjari (WAP) protected area complex in West Africa, characterized by a strong contrast between forested and grassland areas, and observational evidence for cloud enhancement over the forested region. We first conducted a sensitivity analysis to identify the key mechanisms driving cloud formation over forested surfaces. Next, we simulated 27 land restoration scenarios that vary in forest cover (low: 21%, intermediate: 43%, and high: 85%) and in the degree of spatial clustering, in addition to two baseline scenarios (0% and 100% forest cover).

Our results show that a fully forested landscape increases afternoon average cloud cover (8.4%) compared to a grassland-only scenario (3.2%) (Ruijsch et al., 2025). However, the highest afternoon cloud cover (21.1%) occurs for scenarios with intermediate forest cover and strong spatial clustering, driven by enhanced mesoscale circulations. These findings suggest that while forests themselves promote cloud formation in this case study, larger-scale heterogeneity (i.e. a combination of forest and grassland patches) results in particularly strong cloud enhancement. Because clouds play an important role in the Earth’s water and energy balance, this study provides new insights into how the design of land restoration projects impact their local climate benefits.

References:

Ruijsch, J., Teuling, A.J., Taylor, C.M., Steeneveld, G.J., & Hutjes, R.W.A. (2026). Clustered land restoration projects increase cloud formation in West African drylands. Journal of Geophysical Research: Atmospheres,131,e2025JD044393.