Measuring the effects of anthropogenic CO2 emissions on global nutrient intakes: a modelling analysis

Abstract

BackgroundSince the preindustrial era, atmospheric CO2 concentrations have been rising steadily at a pace that is projected to continue unless concerted action is taken to reduce anthropogenic emissions. Meanwhile, several studies have shown that the edible portions of many food crops—namely, wheat, rice, field peas, and potatoes—contain 4–10% less zinc, iron, and protein when grown at CO2 concentrations that are anticipated within the next 50 years. Our study aimed to examine which populations around the world might be most vulnerable to the effect of CO2-related nutritional declines based on their diets. MethodsWe model scenarios under both ambient and increased CO2 concentrations and estimate the loss of nutrients at the population level for each of 152 countries that would occur as a result of anthropogenic CO2 emissions. The micronutrient contributions of individual foods to the diet were calculated by combining two types of data: dietary information derived from food balance sheets that have been expanded using additional data for food production and trade, and each food's nutrient content collected from food composition tables. Crops' change in nutrient content due to elevated CO2 concentrations (550 ppm) were estimated based on previous meta-analyses of experimental data. FindingsWe find that populations in lower-income countries relying particularly on wheat and rice as staple foods and with low amounts of animal-source food in the diet—India, southeast Asia, sub-Saharan Africa, and the Middle East—are at highest risk of increased nutritional deficiency in zinc, iron and protein. 658 million children and women of childbearing age (27% of world total) are at moderate-to-high risk in at least two nutrients. India, which contributes 460 million to the total, is at high risk across all three nutrients and the highest-risk country globally. Furthermore, because of the disproportionate burden on poorer countries, these areas also lack the resilience to combat these effects due to greater reliance on subsistence farming, reduced dietary diversity, lower caloric intake, and greater prevalence of concurrent diseases that could worsen the health effects of nutritional deficiency. InterpretationFuture changes in dietary patterns might alleviate such trends without additional intervention, but they could also exacerbate them. Within the most vulnerable countries, ongoing monitoring and awareness of the effect will be important to stave off potentially higher rates of malnutrition. FundingThe Bill & Melinda Gates Foundation.