0559 GMT February 21, 2019
According to ozemandailychronicle.com, the mechanism is not yet known. Several staple crops were grown in outdoor experiments on three continents at either ambient or enhanced carbon dioxide concentrations. Ambient levels ranged from 363-386 ppm and enhanced levels ranged from 546-584 ppm. Moderate late century levels are expected to be 580-720 ppm. In the tests, nutritional values of zinc, iron, and protein were reduced 5-10 percent in wheat and rice, and in soybeans zinc and iron were reduced by five percent.
These effects were not observed in sorghum and maize. Decreases in zinc concentrations in rice and wheat could cause zinc deficiency in an additional 150-200 million people. Iron deficiencies in grains and rice could also result in higher anemia rates in India and Algeria where this is already a problem. Reduced protein content in wheat and rice could add an additional 1.4 billion people worldwide to be short of protein by 2050. Grazing cattle also face a decrease in nutritional value of their food. Today there are 10.6 grams less protein in every kilogram of plants that cattle eat compared to each kilogram they ate 22 years ago.