Increasing CO2 may threaten human nutrition

Ars Technica » Scientific Method 2014-05-08

Corn (maize) is one of the crops that will retain its mineral content through this century.

According to the UN, wheat, rice, and maize—a mere three out of the Earth's 50,000+ edible plants—provide 60 percent of the world’s plant-derived food energy. In the developing world, they provide up to 70-80 percent of the energy in a person’s daily diet. These crops are key providers of micronutrients like zinc and iron, which they draw up from the soil.

As we continue to spew carbon dioxide into the atmosphere, however, we may be less able to rely on these crops. A meta-analysis indicates that grains and legumes grown at elevated CO2 levels have lower concentrations of zinc and iron, and some crops also have reduced protein levels.

Data was collated from 143 comparisons of crops grown at current CO2 concentrations—about 400 ppm—to those grown under free-air CO2 enrichment conditions. These typically raised the concentrations to around 550 ppm, approximating the levels we are targeted to hit in the next 40-60 years. Crops included wheat, rice, maize, soybeans, field peas, and sorghum, and they were grown in Australia, Japan, and the US. Nutrient levels were measured over one to six growing seasons.

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