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Rising Carbon Dioxide Levels to Decrease Nutrient Density of a Global Food Staple

By Riley Forbes

Whether you believe in climate change or not, there is no denying that science supports the increase of carbon dioxide (CO2) levels in our atmosphere. By the end of the century CO2 emissions are predicted to increase from the current level at 405.29 µmol mol-1, as of October 1st, 2018, to 570 µmol mol-1. While there are many consequences associated with this increase, one obstacle often left undiscussed is food security (McGee, 2018).

Globally, 1 billion people are classified as food insecure, which can be defined as not having sufficient access to nutritious foods. However, as surface temperatures continue to rise, harvests of staple crops, such as rice and corn, could drop by 20 to 40% by 2100, further exacerbating the insecurities (Zhu et al., 2018). To add another level of complexity to this problem, humans require that their diets provide an adequate array of quality nutrition including macronutrients, vitamins, and minerals. Currently, 2 billion people worldwide are nutrient deficient, having not met the recommended daily intake as proposed by the Institute of Medicine. This puts their health at risk through increasing their likelihood of cognitive delay, nerve damaging, obesity, type two diabetes, and many more chronic diseases.

In a recent publication from Science, a group of researchers attempted to evaluate how the changing levels of CO2 might impact populations with limited food diversity that rely “heavily on a single plant-based food source” (Zhu et al., 2018). The researchers conducted their studies on 18 different rice lines, grown in China and Japan, as rice is a vital food source which accounts for about 25% of all global calories and is of particular importance in low- and middle-income Asian countries. Zhu et al. subjected the rice varieties to increased CO2 exposure of 568 – 590 µmol mol-1 with the goal of mimicking future levels of CO2 and determining its impact on nutrient availability.

From this study, the researchers found a statistically significant decrease in the levels protein, iron, and zinc as well as in vitamins B1, B2, B5, B9, and a slight increase in the amount of vitamin E. The drop in these nutrients ranged anywhere from 5 – 30% the level currently found in these rice varieties today. The decrease in these vital nutrients are of particular concern for individuals in low- and middle-income countries who already have and/or are at an increased risk of nutritional deficiencies and rely on rice as a stable source of calories and nutrition. As CO2 levels inevitably increase, these countries will have to consider supporting their citizens’ with other more nutritious food sources to make up for the loss of vitamins and minerals present in their current food staple.

As we look towards the future not only can we can expect atmospheric CO2 levels to rise but the human population is projected to increase to 9.8 billion by 2050 and 11.2 billion by 2100, as estimated by the United Nations Department of Economic and Social Affairs (UN DESA, 2018). The growth of the human population, along with increases in CO2, will further exacerbate current problems regarding food security and nutritional adequacy and is of the utmost importance to bring awareness to in order to secure the health of those currently inhabiting our planet and for generations to come.


C. Zhu, K. Kobayashi, I. Loladze, J. Zhu, Q. Jiang, X. Xu, G. Liu, S. Seneweera, K. L. Ebi, A. Drewnowski, N. K. Fukagawa, L. H. Ziska, Carbon dioxide (CO2) levels this century will alter the protein, micronutrients, and vitamin content of rice grains with potential health consequences for the poorest rice-dependent countries. Sci. Adv. 4, eaaq1012 (2018).

McGee, M. (2018). Daily CO2. Retrieved October 3, 2018, from

World population projected to reach 9.8 billion in 2050, and 11.2 billion in 2100 | UN DESA Department of Economic and Social Affairs. (2017, June 21). Retrieved September 26, 2018, from

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