Rising CO2 levels threaten world nutrition, study warns

As if we didn't have enough problems. Aside from increased temperature, ocean acidification, increased typhoon intensity, and global climate change, increased atmospheric carbon dioxide (CO2) will also result in some of our most important food crops becoming significantly less nutritious than they are today.

 

Higher CO2 levels by 2050

 

The product of a joint collaboration between 8 institutions in Australia, Israel, Japan, and the United States, the new study looked at the responses of rice (Oryza sativa), wheat (Triticum aestivum), maize (Zea mays), soybean (Glycine max), field peas (Pisum sativum), and sorghum (Sorghum bicolor) grown in air with 546 to 586 parts per million (ppm) CO2 compared to those grown in ambient or “normal” CO2 levels (363 to 386 ppm). 

 

The experimental crops were grown in open-air fields using a system called Free Air Concentration Enrichment (FACE) that pumps out, monitors, and adjusts ground-level atmospheric CO2 concentrations to simulate the predicted CO2 concentrations by the year 2050. All other growing conditions - sunlight, soil, water, and temperature - remained the same for control and high CO2 crops. The same cultivars were also used. The experiments were conducted between 1998 and 2010.

 

Zinc, iron, and protein affected

 

Analysis revealed that zinc, iron, and protein content generally decreased with increasing CO2, but the degree of response varied between crops. Wheat showed a 9.3% decrease in zinc, compared to 3.3% decrease in rice. In contrast, rice showed a 7.8% decrease in protein, while wheat showed a 6.3% decrease. The iron decrease in wheat (5.1%) and rice (5.2%) were comparable. The responses of the different rice cultivars varied significantly, prompting the researchers to suggest that breeding cultivars whose micronutrient levels are less vulnerable to changes in CO2 could be considered. However, this has to be weighed against other factors, such as taste, yield, and cost. Sorghum was the least affected crop.

 

"When we take all of the FACE experiments we've got around the world, we see that an awful lot of our key crops have lower concentrations of zinc and iron in them (at high CO2)," said Dr. Andrew Leakey of the University of Illinois, an author on the study. "And zinc and iron deficiency is a big global health problem already for at least 2 billion people."

 

Possible impact on Pinoys

 

According to the Food and Nutrition Research Institute of the Department of Science and Technology (FNRI-DOST), more than 20% of Filipinos across different demographic groups suffer from zinc deficiency. It is most prevalent in elderly males (33.6%), followed by elderly females (24.5%). Zinc is an essential micronutrient and symptoms of zinc deficiency include hair loss, growth retardation, and loss of the sense of taste and smell. Iron deficiency is also another public health concern, with 20.4% of male and 19.2% of female children (aged 6-12) considered anemic. Women are an especially vulnerable group, as 42.5% of pregnant and 31.4% of lactating women are anemic. In the average Filipino diet, rice provides 47% of the dietary energy and 34.75% of the protein (UN Food and Agriculture Organization Food Balance Sheets).

 

While the crops were grown in a diverse set of environments in different countries, more research is needed to determine how the crops will respond when grown in the developing regions of the world, Leakey said. "It's important that we start to do these experiments in tropical climates with tropical soils, because that's just a terrible gap in our knowledge, given that that's where food security is already the biggest issue," he said.

 

The collaborators for this study include researchers from Harvard University (which led the effort); Ben-Gurion University of the Negev, in Beer Sheva, Israel; the University of Illinois at Urbana-Champaign; the University of California, Davis; the U.S. Department of Agriculture's Agricultural Research Service; the National Institute for Agro-Environmental Sciences in Ibaraki, Japan; the University of Melbourne, Australia; the University of Arizona; the University of Pennsylvania; and The Nature Conservancy, Santa Fe, New Mexico. — TJD, GMA News