Climate change is threatening human nutrition, according to experts, who say rising levels of carbon dioxide in the atmosphere are robbing the global population of vital plant nutrients.
That conclusion follows the release of the 2014 National Climate Assessment
, which predicts that extreme weather will disrupt agricultural production, and have negative consequences for food security, both in the U.S. and globally.
The study says the damage will come not only through changes in crop yields, but also from changes in the ways climate affects food processing, storage, transportation and retailing.
Unless something is done, climate change will take significant amounts of dietary zinc and iron away by 2050 from food staples, including rice, wheat, corn, soy, field peas and sorghum. Scientists with the Harvard [University] School of Public Health make the prediction in a new study published in the journal Nature
An estimated 2 to 3 billion people receive 70 percent or more of those essential nutrients from wheat, rice and legumes, particularly in the developing world.
Reductions in nutrients
Samuel Myers, a researcher in Harvard’s Department of Environmental Health in Boston, said, “What our study is showing is that, unequivocally, as CO2 concentrations rise up to levels that we expect to see in the next 40 years, there are very significant reductions in nutrients that are really important for public health.”
Zinc is essential for a healthy immune system, according to Myers, helping to fend off diarrheal diseases, pneumonia and measles, while deficiencies in iron cause anemia and decreased IQ in children. Mothers who are severely anemic are at increased risk of death.
Some 2 billion people worldwide suffer from zinc and iron deficiencies, resulting in a loss of 63 million life years annually. Life years are a measurement of years that are lost due to disability and disease.
For the study, the nutrient content of plants exposed to artificially elevated levels of carbon dioxide was compared to that of plants grown naturally in nearby fields.
Data was analyzed from 41 cultivars, or specially bred varieties of grains and legumes, from seven different locations in Japan, Australia and the United States where the CO2 experiments were carried out.
The results showed significant decreases in zinc and iron in wheat, rice and legumes at the highest concentrations of carbon dioxide. In some of the plants, researchers also noted decreases in protein stores.
As a hedge against rising atmospheric carbon dioxide, Myers said it may be possible to grow varieties of food crops that are immune to the negative impacts of CO2.
“For example, we looked at 18 rice cultivars and we found that some rice cultivars are much more sensitive to the CO2 effect than others," he said. "And that led us to speculate in our paper that conceivably, there may be an opportunity to try to develop cultivars of crops that are less sensitive to the CO2 effect.”
Ultimately, Myers said the only way to counteract severe depletions in natural sources of zinc and iron is to hold carbon dioxide concentrations steady, while developing enriched grain crops or ones that are CO2 resistant.