Quality of food to decline as CO2 levels go up

If CO2 levels continue to rise as expected, staple crops like wheat, barley and potatoes could become less nutritious. Researchers at the University of California, Davis, conducted a field study showing wheat crops were less efficient at converting nitrates into proteins under conditions of heightened CO2 levels. Previous studies have shown that CO2 inhibits the assimilation of nitrates in plants, but this is the first time the phenomenon has been demonstrated in field-planted crops. "Food quality is declining under the rising levels of atmospheric carbon dioxide that we are experiencing," said Arnold Bloom, lead author of the new study and a professor in UC-Davis's Department of Plant Sciences. "Several explanations for this decline have been put forward, but this is the first study to demonstrate that elevated carbon dioxide inhibits the conversion of nitrate into protein in a field-grown crop," he added. Bloom and his fellow researchers -- including two scientists from the USDA's Arid-Land Agricultural Research Center in Arizona -- estimate that in the coming decades the proteins available for human consumption in wheat, rice, tubers and other grains will decline by roughly 3 percent. This latest study, published in the online journal Nature Climate Change, arrives only a few weeks after a group of international scientists estimated crop yields will decline by 2 percent each decade as the planet continues to warm.