Abstract
SummaryBackgroundIncreasing atmospheric concentrations of carbon dioxide (CO2) affect global nutrition via effects on agricultural productivity and nutrient content of food crops. We combined these effects with economic projections to estimate net changes in nutrient availability between 2010 and 2050.MethodsIn this modelling study, we used the International Model for Policy Analysis of Agricultural Commodities and Trade to project per capita availability of protein, iron, and zinc in 2050. We used estimated changes in productivity of individual agricultural commodities to model effects on production, trade, prices, and consumption under moderate and high greenhouse gas emission scenarios. Two independent sources of data, which used different methodologies to determine the effect of increased atmospheric CO2 on different key crops, were combined with the modelled food supply results to estimate future nutrient availability.FindingsAlthough technological change, market responses, and the effects of CO2 fertilisation on yield are projected to increase global availability of dietary protein, iron, and zinc, these increases are moderated by negative effects of climate change affecting productivity and carbon penalties on nutrient content. The carbon nutrient penalty results in decreases in the global availability of dietary protein of 4·1%, iron of 2·8%, and zinc of 2·5% as calculated using one dataset, and decreases in global availability of dietary protein of 2·9%, iron of 3·6%, and zinc of 3·4% using the other dataset. The combined effects of projected increases in atmospheric CO2 (ie, carbon nutrient penalty, CO2 fertilisation, and climate effects on productivity) will decrease growth in the global availability of nutrients by 19·5% for protein, 13·6% for iron, and 14·6% for zinc relative to expected technology and market gains by 2050. The many countries that currently have high levels of nutrient deficiency would continue to be disproportionately affected.InterpretationThis approach is an improvement in estimating future global food security by simultaneously projecting climate change effects on crop productivity and changes in nutrient content under increased concentrations of CO2, which accounts for a much larger effect on nutrient availability than CO2 fertilisation. Regardless of the scenario used to project future consumption patterns, the net effect of increasing concentrations of atmospheric CO2 will slow progress in decreasing global nutrient deficiencies.FundingUS Environmental Protection Agency, Consultative Group on International Agricultural Research (CIGAR) Research Program on Policies, Institutions and Markets (PIM), and the CGIAR Research Program on Climate Change and Food Security (CCAFS).
Highlights
Despite substantial decreases in the rate of global undernutrition over the past few decades, a large global burden of disease associated with deficits in intake of protein, iron, zinc, and other nutrients remains.[1,2] progress in decreasing undernutrition has stagnated or deteriorated in many countries.1 25–30% of the global population are deficient in at least one key micronutrient.[3]
Increasing population and nutrient demands and the effects of climate change have the potential to exacerbate these threats to global food security.[8]
By synthesising the effect of changes in both nutrient content and productivity of key agricultural commodities due to increased CO2 and climate change, economic changes, and CO2 yield fertilisation, we provide a more comprehensive estimate of the effect of climate change on agriculture and global nutrient availability
Summary
Despite substantial decreases in the rate of global undernutrition over the past few decades, a large global burden of disease associated with deficits in intake of protein, iron, zinc, and other nutrients remains.[1,2] progress in decreasing undernutrition has stagnated or deteriorated in many countries.1 25–30% of the global population are deficient in at least one key micronutrient.[3] This proportion includes an estimated 10–15% of people who are at risk of insufficient iron intake,4 17% at risk of zinc deficiency,[5,6] and 12% at risk of protein deficiency.[7] Increasing population and nutrient demands and the effects of climate change have the potential to exacerbate these threats to global food security.[8].
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