Estimated Effects of Future Atmospheric CO2 Concentrations on Protein Intake and the Risk of Protein Deficiency by Country and Region

Background: Crops grown under elevated atmospheric CO2 concentrations (eCO2) contain less protein. Crops particularly affected include rice and wheat, which are primary sources of dietary protein for many countries. Objectives: We aimed to estimate global and country-specific risks of protein deficiency attributable to anthropogenic CO2 emissions by 2050. Methods: To model per capita protein intake in countries around the world under eCO2, we first established the effect size of eCO2 on the protein concentration of edible portions of crops by performing a meta-analysis of published literature. We then estimated per-country protein intake under current and anticipated future eCO2 using global food balance sheets (FBS). We modeled protein intake distributions within countries using Gini coefficients, and we estimated those at risk of deficiency from estimated average protein requirements (EAR) weighted by population age structure. Results: Under eCO2, rice, wheat, barley, and potato protein contents decreas...