While many of the world’s politicians debate whether or not the effects of climate change are real, scientists in Israel are making discoveries that clearly point to their worrisome omens for the not-so-distant future.
Crops that provide a large share of the global population with most of their dietary zinc and iron will have significantly reduced concentrations of those nutrients at the elevated levels of carbon dioxide (CO2) anticipated by around 2050, according to researchers at Ben-Gurion University in the Negev. Given that an estimated two billion people suffer from zinc and iron deficiencies, resulting in a loss of 63 million life years annually from malnutrition, the reduction in these nutrients represents the most significant health threat ever to be associated with climate change.
Putting a FACE on nutrient deficiency
Previous studies of crops grown in greenhouses and chambers at elevated CO2 had found nutrient reductions, but those studies were criticized for using artificial growing conditions. Experiments using free air carbon dioxide enrichment (FACE) technology have subsequently become the standard since FACE allows plants to be grown in open fields at elevated levels of CO2. However, even prior studies using FACE had small sample sizes and have been inconclusive.
Dr. Itai Kloog of the Department of Geography and Environmental Development and his colleagues analyzed data involving 41 cultivars of grains and legumes from seven different FACE locations in Japan, Australia, and the United States. They tested the nutrient concentrations of the edible portions of wheat, rice, maize, sorghum, soybeans, and field peas.
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The results showed a significant decrease in the concentrations of zinc, iron, and protein in wheat and rice. For example, zinc, iron, and protein concentrations in wheat grains grown at the FACE sites were reduced by as much as 9.3%, 5.1%, and 6.3% respectively, compared with wheat grown at normal CO2 levels. Nutritional zinc and iron levels were also significantly reduced in legumes. The team published their findings in last month’s issue of “Nature” magazine.
Discovering the future of global nutrition
The finding that these grains and legumes lost these nutrients at elevated CO2 is, of course, tremendously significant for the future of global food consumption.
It is estimated that 2-3 billion people around the world receive 70 percent or more of their dietary zinc and/or iron from these crops, particularly in the developing world, where zinc and iron deficiency is already a major health concern. With CO2 levels predicted to reach the elevated levels used in the experiment by 2050, the global health implications are alarming. However, one surprising finding may offer hope for mitigation. Kloog’s team found that zinc and iron varied substantially across cultivars of rice. According to the researchers, this discovery suggests that there could be an opportunity to breed reduced sensitivity to the effect of elevated CO2 into crops in the future.