Impact of stratospheric aerosol injection on rangeland productivity and animal production in Africa

Résumé

Introduction African rangelands are crucial to the socio-economic security of millions of people in Africa. Studies have highlighted that climate change poses a significant threat to rangeland productivity and proposed stratospheric aerosol injection (SAI)–a geoengineering strategy–as a means to offset temperature-related impacts. However, the effectiveness of SAI in mitigating climate change impacts on African rangelands remains unknown. This study examines the potential influence of SAI on rangeland production in Africa by analyzing climate-vegetation interactions (composition and biomass production), their cascading effects on animal production, and the associated economic implications. Methods Bias-corrected climate simulation datasets from the Assessing Responses and Impacts of Solar Climate Intervention on the Earth System with Stratospheric Aerosol Injection (ARISE-SAI-1.5) project were used to drive Af-Range, an offline process-based dynamic rangeland vegetation model. Two experiments were simulated: (1) SSP2-4.5 climate scenario without SAI and (2) SSP2-4.5 with SAI implementation. Results Under SSP2-4.5, Africa warms, with drying in West, Central, and Southern regions, and wetting in East Africa. SAI reduces warming but alters rainfall–drying Southern, Central, and East Africa while wetting West Africa. SSP2-4.5 increases vegetation cover but reduces biomass, whereas SAI decreases vegetation cover while increasing biomass. These ecological shifts are shaped by competition among plant functional types and soil characteristics. Animal production responses vary by region and forage characteristics: wild herbivores benefit from biomass gains, while domestic livestock show region-specific sensitivities–biomass drives productivity in North and West Africa, vegetation composition dominates in Central and Southern Africa, and East African livestock respond to both cover and productivity. Economically, SAI benefits livestock production in North, West, and East Africa but causes losses in Central and Southern Africa. Discussion These findings highlight the complex trade-offs associated with SAI deployment in African rangelands. While SAI may alleviate warming, its influence on rainfall patterns and vegetation dynamics introduces region-specific ecological and economic consequences. The reliance on a single climate model and one SAI injection strategy introduces considerable uncertainty in the results, underscoring the need for multi-model approaches and diverse intervention designs. Region-specific adaptation strategies will be essential to ensure equitable outcomes across African rangelands.

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