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Abstract

Climate change driven shifts in temperature, precipitation patterns, and atmospheric CO2 concentrations threaten both productivity and nutritional quality of maize, a staple crop that underpins daily energy and protein intake for millions of households in Africa and beyond. While several studies focus on yield, impacts on maize grain nutrient composition remain less assessed. Here, we use the Agricultural Production Systems simulator (APSIM) crop model to estimate climate impacts on maize yield and grain protein levels across 16 West African countries under two contrasting shared socioeconomic pathways (SSP1-RCP2.6 and SSP3-RCP7.0). Our model results show spatially heterogeneous climate impacts across the region, with a mean reduction of −5.7% (range: −43.7%–49.7%) for yield and −4.8% (range: −42.6%–54.3%) for protein content under the high-emission scenario by mid-century. Spatially, protein concentration shows an inverse trend with yield: areas that experience yield and protein content gains show reductions in protein concentration, and vice versa. Across the region, protein concentration shows a mean increase of 4.6% (range: −4.9%–19.3%). Northern regions exhibit larger percentage yield increases, driven by higher projected precipitation and comparatively low baseline yields. By jointly evaluating productivity and nutritional quality at subcontinental scale, we demonstrate that yield-only assessments may underestimate future food system vulnerability and thus a potential trade-off between yield and protein concentration. Since adaptation measures that aim to stabilize or increase maize grain yield may jeopardize improvements in grain quality, further research on region-specific measures that optimize grain yield and quality are warranted and discussed in this study.