Nutritional challenges of staple crops due to increasing atmospheric carbon dioxide levels: Case of Sub-Saharan Africa

The atmospheric concentration of carbon dioxide (CO₂) has risen from pre-industrial levels of 280 parts per million (ppm) to over 410 ppm today, with projections indicating further increases. Sub-Saharan Africa (SSA), despite contributing only 3 % of global CO₂ emissions, faces significant vulnerability due to its dependence on agriculture, with smallholder farmers particularly at risk. This review focuses on the impact of elevated CO₂ levels on the nutritional quality of key staple crops in SSA. Research from Free-Air CO₂ Enrichment (FACE) and Open-Top Chamber (OTC) experiments highlights a reduction in essential micronutrients, including iron, zinc, and protein, in these crops under elevated CO₂ conditions. Given the already low micronutrient content of these crops in SSA, further reductions intensify food insecurity and malnutrition in the region, where approximately 80 % of the population relies on agriculture for their livelihoods. This review also explores potential strategies to mitigate the adverse effects of elevated CO₂ on crop nutrition in SSA. Integrated mitigation measures such as crop diversification, bio-fortification, climate-smart agriculture, and reforestation are identified as critical to improving food security. Furthermore, raising awareness about the nutritional impacts of climate change and investing in the development of resilient crop varieties are essential for long-term sustainability. The review emphasizes the need for coordinated efforts at local, national, and international levels to protect vulnerable populations and strengthen agricultural systems in SSA, ensuring that they can adapt to the ongoing challenges posed by rising atmospheric CO₂. The graphical abstract of this article was updated in November 2025. • Rising CO₂ levels reduce nutrient density in staple crops crucial for Sub-Saharan Africa. • Protein and micronutrient deficiencies in maize, rice, and wheat are intensified by climate impacts. • The nutritional decline in staple foods poses serious health risks in already vulnerable populations.