Australasian Science: Australia's authority on science since 1938

CO2 Rise Threatens Nutrition

An international study has concluded that the nutritional quality of major food crops is depleted at levels of atmospheric carbon dioxide that are expected in 2050.

The study, published in Nature, gathered data from seven locations across three continents for 40 cultivars of six crops. It found that elevated carbon dioxide levels were associated with lower concentrations of zinc and iron in wheat, rice and legume crops, and lower protein concentrations in wheat and rice crops.

The results have important implications for global health, as these food crops are the staple diet of a large proportion of the global population. With dietary deficiencies of zinc and iron currently affecting about two billion people, reduced dietary access to these nutrients represents a very significant global health threat.

The research was conducted in Free Air Carbon dioxide Enrichment (FACE) sites that allow plants to be grown in open fields at the atmospheric carbon dioxide levels expected in 2050. At the Australian Grains FACE site in western Victoria, researchers from the Primary Industries Climate Challenges Centre examined the effects of future atmospheric conditions on crop yield, grain quality, soil health and pest populations over 7 years for crops of wheat, peas, canola and other pulse crops.

Atmospheric carbon dioxide levels are expected to increase by about 40% over the next 35 years. While this will support yields and plant growth through the carbon “fertilisation effect”, it will also have many downsides. Prof Michael Tausz of the University of Melbourne, who co-authored the Nature study, says we need to be prepared so that Australian crop industries can adapt to the future. “If we are planning on breeding new crop varieties, or adopting new technologies or practices in food production to counter these drawbacks, then 35 years is not a very long time,” he said.

“What it means is that any new strategy in crop production to respond to these challenges, be it in plant breeding or agronomic management, must already be evaluated for its efficiency under the future high carbon dioxide atmosphere where it actually has to perform.”