Impact of Rising CO2 on Food Security and Human Health Risks and Potential Adaptation Strategies.

Decades of Free Air CO2 Enrichment (FACE) experiments show that projected atmospheric carbon dioxide (CO2) increases significantly influence crop systems, impacting food security. Firstly, elevated CO2 (eCO2) benefits global C3 crop yields, despite substantial genetic variation. Lower-than-expected rice yield increases highlight the potential to augment the CO2 fertilization effect (CFE) by enhancing nitrogen (N) uptake to facilitate carbon (C) assimilation. Secondly, CFE consistently correlates with declining nutritional quality. Concomitant CO2 and temperature increases synergistically elevate toxic arsenic (As) in rice grain, projecting substantial cancer case increases in major rice-consuming countries. This assessment underscores the urgency for strategies mitigating nutrient decline and As exposure from near-term climate change. Thirdly, current estimates suggest long-term eCO2 minimally impacts soil N availability. However, risks include decreasing soil phosphate (P) availability and intensifying greenhouse gas emissions (methane [CH4], nitrous oxide [N2O]), challenging food security sustainability. Fourthly, global food security inequity will likely worsen. Poorer regions, often heavily reliant on few cereal crops and affected by climate variability and uneven resource distribution, are more vulnerable to eCO2. Thus, implementing diverse, region-specific adaptation strategies-encompassing agronomic management, crop breeding, and policymaking-is crucial for establishing climate-resilient agricultural ecosystems.