Journal Article

Impacts of Idealized Land Use and Land Management Changes on Weather Extremes in West Africa

Kunstmann, Harald, Seydou, Abdel Nassirou Yahaya, Huber‐García, Verena, Arnault, Joel, Duveiller, Gregory, Quesada, Benjamin, Oussou, Francis E., Laux, Patrick, Bliefernicht, Jan, Sy, Souleymane, Hirner, Andreas, Fersch, Benjamin

2025

Overview

Land‐based mitigation strategies, such as afforestation and avoided deforestation, are critical to achieving the Paris Agreement's goal of limiting global warming to 1.5°C or 2°C. However, the biophysical impacts of anthropogenic land use and land cover change (LULCC), particularly deforestation and afforestation, on extreme weather events in West Africa remain poorly understood at the regional scale. In this study, we present the first high‐resolution LULCC experiments (at 3 km resolution, covering 2012–2022) using the advanced fully coupled atmosphere‐hydrology WRF‐Hydro model system to assess the potential impacts of idealized land use and land management scenarios on extreme events in the West African savannah region. By analyzing 18 extreme weather indices, we show that deforestation significantly affects temperature extremes (up to 0.45 ± 0.04°C), with effects on regional rainfall extremes being approximately twice as pronounced as those on mean rainfall conditions, along with a significant increase in the number of dry days. Conversely, afforestation generally leads to increases in both mean and extreme precipitation, along with fewer dry days and shorter drought durations. Notably, afforestation produces contrasting responses in temperature extremes depending on vegetation type: converting grassland to mixed or evergreen forest reduces extreme heat via increased transpiration, while conversion to savanna or woody savanna may intensify heat extremes due to albedo‐induced warming effects. Plain Language Summary West Africa is currently experiencing extensive agricultural intensification associated with rapid population growth. Those anthropogenic land use and land‐cover changes (LULCC) can have significant impacts on regional climate but also on extreme weather events, posing high vulnerability to human, natural, and economic systems. However, the effects of LULCC (including deforestation and afforestation) on extreme events in West Africa remain largely unexplored at the regional scale, lacking consensus. This study employs high‐resolution LULCC simulations (3 km resolution, 2012–2022) using an advanced coupled atmosphere‐hydrology model to evaluate the impacts of land cover transition scenarios on extreme events in the West African Savanna. The results indicate that deforestation significantly influences temperature extremes, while it consistently affects regional rainfall extremes—about twice as much as mean rainfall changes—and substantially increases the number of dry days. Conversely, afforestation scenarios generally lead to increases in both mean and extreme precipitation, fewer dry days, and shorter drought durations. Notably, afforestation with mixed or evergreen forests mitigates extreme heat through enhanced plant transpiration. However, certain forest types, such as woody savanna or savanna, can exacerbate heat extremes due to albedo‐induced warming effects. Key Points Deforestation of the West African savanna region significantly intensifies temperature extremes (up to 0.45 ± 0.04°C) and increases drought lengths Afforestation with mixed or evergreen forests mitigates extreme heat, while woody savanna or savanna may worsen it due to albedo induced warming effects Afforestation leads to increased mean and extreme precipitation, more frequent wet days, and shorter drought durations

• Publisher: John Wiley & Sons, Inc,Wiley
• Subject: Afforestation / Agriculture / Albedo / Anthropogenic factors / Biogeochemistry / Climate change / Coniferous forests / Deforestation / Drought / Extreme heat / Extreme high temperatures / Extreme weather / Global warming / Grasslands / Greenhouse gases / Human influences / Hydrologic cycle / Hydrology / Land cover / Land management / Land use / land‐based mitigation / Paris Agreement / Precipitation / Radiation / Rainfall / Savannahs / Temperature extremes / Transpiration / Vegetation / Vegetation type / Weather / weather extreme / Weather index / West Africa