A Modeling Approach Combining Elevated Atmospheric CO2 Effects on Protein, Iron and Zinc Availability with Projected Climate Change Impacts on Global Diets

Abstract

Background. Increases in atmospheric concentrations of carbon dioxide (eCO2) affect global nutrition through impacts on agricultural productivity and nutrient content of food crops. Methods. We used a global economic model of the agricultural sector to project per capita availability of protein, iron, and zinc in 2050. Estimated changes in productivity of individual agricultural commodities were used to model effects on production, trade, prices, and consumption. The resulting food supply was combined with two sources of data on eCO2 effects on nutrient content. Findings. While technological change, market responses, and the productivity effects of CO2 yield fertilization are projected to increase global availability of dietary protein, iron, and zinc, these increases are dampened by negative effects of climate change impacts on productivity and eCO2 impacts on nutrient content. Both datasets show projected eCO2 decreases global availability of nutrients in crops by enacting a 2·4% to 4·3% penalty on expected gains by mid-century. The penalty on nutrient content of wheat is ~3 times larger. Many countries currently experiencing high levels of nutrient deficiency would continue to be disproportionately affected. Interpretation. This approach represents an improvement in estimating future impacts on global food security by simultaneously projecting climate change impacts on crop productivity and changes in nutrient content under eCO2, which accounts for a much larger effect on nutrient availability than CO2 fertilization. Regardless of the scenario used to project future consumption patterns, the net effect of rising atmospheric CO2 concentrations will slow progress in achieving reductions in global nutrient deficiencies. Funding: This research was funded by the U.S. Environmental Protection Agency under contract EPBPA16H0002. Support was also provided through the CGIAR Research Programs on Policies, Institutions, and Markets (PIM) and Climate Change, Agriculture and Food Security (CCAFS). The views expressed in this document are those of the authors and do not necessarily reflect those of their affiliated institutions including the U.S. Environmental Protection Agency or the U.S. Department of Agriculture. Declaration of Interest: The authors declare no competing interests.