PlantwisePlus Blog

Wheat field  © Lauren Tucker

Wheat field © Lauren Tucker

New research suggests that rising levels of carbon dioxide will not only have a devastating effect on our climate but will lower the nutritional value of many staple crops, increasing deficiencies in iron and zinc.

It is estimated that around 2 million people worldwide suffer from deficiencies in zinc and iron which can cause illnesses such as anaemia, impairment of brain development and stunted growth. A recent study published in Nature by researchers at Harvard University, found that CO2 concentrations projected to occur in 2050 can significantly reduce the nutritional value of some of the world’s major cereals and legumes.

The study

Free Air CO2 Enrichment (FACE) plot © USDA

Free Air CO2 Enrichment (FACE) plot © USDA

Carried out over 6 growth years on field sites in Australia, Japan and the US, the study compared the nutritional content of crops grown in ambient CO2 concentrations (currently 400 ppm) to crops that were enriched with CO2 (between 546-586 ppm). Free Air Carbon dioxide Enrichment (FACE) technology allows plants to be grown at elevated CO2 concentrations in open fields. The nutritional content of the edible portions of 41 genotypes of C3 and C4 legumes and grains (plants that use C3 and C4 carbon fixation pathways) were tested.


C3 crops most affected

The researches at Harvard detected a significant decrease in zinc and iron in the C3 crop species, these included crops such as wheat, rice, soybeans and peas. For example, wheat grains grown in the FACE plots had 9% less zinc and 5% less iron. However, CO2 enhancement of C4 crop species such as maize and sorghum, showed little impact on nutritional content.

Poorest will be hit hardest

Around 2.4 billion people receive at least 60% of their zinc and iron from C3 crops, predominantly in developing countries. The findings present a major threat to human health and nutrition in these countries. Hannah Stoddart, head of Oxfam’s food and climate policy efforts states “This is yet another example of the impact climate change is already having on people’s ability to grow and access the nutritious food they need. With 25 million more children under five at risk of malnutrition by 2050 because of climate change, action to cut emissions and support communities to adapt is crucial.”


April saw the global daily CO2 concentration exceed 400 ppm for the first time in millions of years. Before the industrial revolution the atmospheric CO2 concentration was 280 ppm. Samuel Myers, the lead author of the study says ‘There will be many more surprises as we remake the environmental conditions on the planet. As a civilisation we are now living with 400 ppm for the first time: it’s a new world.”

Myers suggested that developing new breeds of the major C3 crops should be a global effort. The Harvard researchers found that different cultivars of rice contained different concentrations of zinc and iron. This therefore suggests opportunity for breeding cultivars of crops that are resistant to the increase in ambient CO2 concentrations. In addition to this breeding effort the World Bank has made a commitment to face this issue by using a non-transgenic method to enhance the nutritional value of crops, known as bio-fortification.




  1. raziqkakar on 16th May 2014 at 2:09 PM
  2. Alice on 12th July 2014 at 6:44 PM

    This is a poor quality small-scale study that pretends to be bigger and than it really is. It has been well-known that high CO2 reduces nutrients and protein in crops results. No surprise here. What is surprising is the amount of money these researchers waisted on it.

    The study was called: Another Bad Nature paper.

    Unfortunately, naive reporters can be easily fooled by Nature & Harvard prestige.

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