Rising carbon dioxide levels could rob food crops of key nutrients, putting more people at risk of malnutrition.
According to a 2014 study, higher levels of carbon dioxide in the atmosphere are likely to lower the level of protein, iron and zinc in rice, wheat, peas and other food crops. The study was led by Samuel Myers, an environmental health researcher at Harvard's School of Public Health.
Myers and colleagues wanted to quantify what the changes might mean for people around the world and to do this they built a new database detailing the foods people in each country eat and the nutrient content of those foods. The database lists the "per capita consumption of 225 foods for 152 different countries," and also accounts for differences in diets in each country on the basis of age and gender.
With the database, the researchers were able to calculate the number of people within each country that were not getting enough of certain nutrients. They were then able to project changes in the protein and iron content of their diets through 2050. The results were published in two new studies published yesterday.
According to one study published in Environmental Health Perspectives, the projected decreases in the protein content of food crops might render 150 million additional people at risk of protein deficiency by 2050.
Researchers say they still had no clear understanding of why carbon dioxide emissions sap protein and other nutrients from plants, but the mystery is one that could have devastating global consequences.
According to a leading hypothesis, carbon dioxide might up the amount of starch in plants, thereby reducing protein and other nutrients.
However, according to Myers, the experiments did not back the theory. ''The short answer is we really have no idea,'' he told AFP.
''We've looked into it pretty extensively.''