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Over the past fifteen years, the iconoclastic mathematician Irakli Loladze has isolated a dramatic effect of carbon dioxide on human nutrition unanticipated by plant physiologists: it can make plants bigger, but those bigger plants are less nutritious. “Every leaf and every grass blade on earth makes more and more sugars as CO2 levels keep rising,” Loladze told Politico, in a story about his work headlined “The Great Nutrient Collapse.” “We are witnessing the greatest injection of carbohydrates into the biosphere in human history—[an] injection that dilutes other nutrients in our food supply.” Since 1950, much of the good stuff in the plants we grow—protein, calcium, iron, vitamin C, to name just four—has declined by as much as one-third, a landmark 2004 study showed. Everything is becoming more like junk food. Even the protein content of bee pollen has dropped by a third. The problem has gotten worse as carbon concentrations have gotten worse. Recently, researchers estimated that by 2050 as many as 150 million people in the developing world will be at risk of protein deficiency as the result of nutrient collapse, since so many of the world’s poor depend on crops, rather than animal meat, for protein; 138 million could suffer from a deficiency of zinc, essential to healthy pregnancies; and 1.4 billion could face a dramatic decline in dietary iron—pointing to a possible epidemic of anemia. In 2018, a team led by Chunwu Zhu looked at the protein content of eighteen different strains of rice, the staple crop for more than 2 billion people, and found that more carbon dioxide in the air produced nutritional declines across the board—drops in protein content, as well as in iron, zinc, and vitamins B1, B2, B5, and B9. Really everything but vitamin E. Overall, the researchers found that, acting just through that single crop, rice, carbon emissions could imperil the health of 600 million people. In previous centuries, empires were built on that crop. Climate change promises another, an empire of hunger, erected among the world’s poor.
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