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By Stephen Leahy
“Two billion people already suffer from low levels of zinc and iron. It is a huge burden on global health, "said Samuel Myers, from the Harvard University School of Public Health and one of the authors of the study" Increased CO2 threatens human nutrition, "published in the edition of the Scientific journal Nature on Wednesday 7.
Zinc and iron deficiencies have a wide range of human health impacts, including increased vulnerability to infectious diseases, anemia, higher levels of maternal mortality, and lower IQ. More than 2.4 billion people receive these key nutrients through the consumption of rice, wheat, corn, soybeans, peas and sorghum, Myers told IPS.
The scientist and his Harvard colleagues evaluated data obtained from 143 experimental crops with CO2 levels that are 100 percent higher than the pre-industrial average, since at the current rate of industrial emissions, CO2 in the atmosphere will double by 2060. Wheat grown under these conditions has 9.3 percent less zinc and 5.1 percent less iron than plants at the current CO2 concentration. "We found significant effects of high CO2 for all of these crops, but some varieties of seeds performed better than others," Myers said.
The nutritional content of many food crops has declined in the past 100 years, according to Myers. One reason is that farmers favored rapid growth and yield without regard for nutrition. In addition, current CO2 levels are 42 percent higher than 150 years ago.
"Higher levels of CO2 help plants grow faster, but that's mostly in the form of increased starch and sugars," said David Wolfe, professor of plant and soil ecology at the US University of Cornell.
"There are more carbohydrates," that is, starch and sugar, "but less protein and nutrients," added Wolfe, who was not involved in the Harvard study. This situation causes what some call "hollow foods", that is, foods with insufficient nutrition, which could be one of the causes of the rapid increase in obesity. People may eat more to get the nutrition they need, said Ken Warren, a spokesman for The Land Institute, a US agricultural research center.
Crops take minerals, trace elements and other properties from the earth every year. Modern agriculture returns some chemical fertilizers to the land that do not replace all that was lost, Warren told IPS.
A 2006 British government analysis of nutrients in meat and dairy products found that the mineral content of milk, cheese and beef decreased by as much as 70 percent compared to the 1930s.
Parmesan cheese had 70 percent less magnesium and calcium, beef short ribs contained 55 percent less iron, chicken 31 percent less calcium and 69 percent less iron, while milk also revealed a sharp decrease in the amount of iron and a 21 percent reduction in magnesium.
Copper, an important trace mineral and essential nutrient consumed in small amounts, also had a 60 percent drop in meats and a 90 percent drop in dairy products, according to the British study.
High-yield crops and intensive farming methods are believed to be responsible for this, according to The Food Commission, the independent organization that published that study.
The measured impacts of high CO2 levels on food crops included in the Harvard study do not replicate the higher temperatures and extreme weather conditions expected for the middle of this century.
Other research revealed that increased heat stresses plants, and while the higher CO2 level generates larger plants, their yields were much lower, Cornell's Wolfe noted.
Food cultivation in the United States will be more problematic with climate change, especially in the western state of California, the Southwest and parts of the Great Plains, according to the National Climate Assessment that the government of that country published on Tuesday 6.
The evaluation, which took four years, constitutes a conclusive scientific statement about the current and future impacts of carbon pollution in the United States.
The anticipated rise in temperatures will dry out the land, making it impossible to grow food without extensive irrigation. The region has already suffered a drought for 10 years that will surely worsen.
Warmer temperatures also increase evaporation, further drying out soils and making irrigation less effective. Underground water resources are also in all indicated areas.
"California and the Southwest face huge water problems," warned Wolfe, one of 300 scientists who contributed to the assessment.
He added that "California has the perfect climate for growing food at the moment, but it won't have it if the weather gets hotter."
There is little doubt that California and the rest of the United States will have higher temperatures unless CO2 emissions drop in that country and the rest of the world. While the western half of the North American country is increasingly dry, the eastern half, and in particular the northeast, will receive heavier rains and more flooding.
The Northeast will experience more droughts in the summers, but when the rains come, they will come like deluge, according to Wolfe. In the last decade the region experienced extremely erratic winter weather.
In 2012, the extreme warmth of winter allowed fruit crops to flower four weeks earlier, but then a severe frost occurred that caused hundreds of millions of dollars in losses.
"Unpredictability is the biggest challenge for farmers," Wolfe said. The scientist added that he is optimistic, but for the future he foresees food with higher prices, above what the poor population can afford, and a lot of disruption for farming communities. American food producers are going to need help adjusting, in terms of education and funding.
“We have to go beyond crop insurance. The change is risky for farmers and many do not have the funds to adapt to what is coming, ”warned Wolfe.