A new study suggests that having more CO2 in the atmosphere will cause levels of zinc and iron in important staple crops to drop.
There are two things you want to get from a harvest. First there’s yield, the amount of grains, beans, or fruit you pull from the fields—and that’s where the focus is placed much of the time, both from the farmer’s perspective and in terms of plant breeding and global development conversations. The other, which isn’t so apparent on the farm, is nutrition. A study published this week in Nature suggests that as CO2 levels in the atmosphere increase in the coming decades, yields may increase. But even as farmers have more wheat, rice, and beans to harvest and eat, the nutrition levels in those staple crops—namely, zinc and iron—are going to drop.
Just last year, the world crossed the dubious threshold of 400 parts per million of carbon dioxide in the atmosphere. By using CO2 jets placed around test plots, the study created growing conditions that approximate a future in which those levels creep upward of 500 parts per million. The grains and legumes grown in this environment had anywhere between 5 and 10 percent less iron, zinc, and protein too. The increase in nutritional deficiencies these drops could cause “represents the most significant health threat ever shown to be associated with climate change,” according to a Harvard press release.
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