Quantcast

Rising CO2 Levels Will Make Staple Crops Less Nutritious

Food

At the elevated levels of atmospheric carbon dioxide (CO2) anticipated by around 2050, crops that provide a large share of the global population with most of their dietary zinc and iron will have significantly reduced concentrations of those nutrients, according to a new study led by Harvard School of Public Health (HSPH). Given that an estimated 2 billion people suffer from zinc and iron deficiencies—resulting in a loss of 63 million life years annually from malnutrition—the reduction in these nutrients represents the most significant health threat ever shown to be associated with climate change.

Researchers tested the nutrient concentrations of the edible portions of wheat and rice — among other crops — and found a significant decrease in the concentrations of zinc, iron, and protein.

“This study is the first to resolve the question of whether rising CO2 concentrations—which have been increasing steadily since the Industrial Revolution—threaten human nutrition,” said Samuel Myers, research scientist in the Department of Environmental Health at HSPH and the study’s lead author. The study appears online May 7 in Nature.

Some previous studies of crops grown in greenhouses and chambers at elevated CO2 had found nutrient reductions, but those studies were criticized for using artificial growing conditions. Experiments using free air carbon dioxide enrichment (FACE) technology became the gold standard as FACE allowed plants to be grown in open fields at elevated levels of CO2, but those prior studies had small sample sizes and have been inconclusive.

The researchers analyzed data involving 41 cultivars (genotypes) of grains and legumes from the C3 and C4 functional groups (plants that use C3 and C4 carbon fixation) from seven different FACE locations in Japan, Australia and the U.S. The level of CO2 across all seven sites was in the range of 546 to 586 parts per million (ppm). The researchers tested the nutrient concentrations of the edible portions of wheat and rice (C3 grains), maize and sorghum (C4 grains), and soybeans and field peas (C3 legumes).

The results showed a significant decrease in the concentrations of zinc, iron and protein in C3 grains. For example, zinc, iron and protein concentrations in wheat grains grown at the FACE sites were reduced by 9.3 percent, 5.1 percent, and 6.3 percent, respectively, compared with wheat grown at ambient CO2. Zinc and iron were also significantly reduced in legumes; protein was not.

The finding that C3 grains and legumes lost iron and zinc at elevated CO2 is significant. Myers and his colleagues estimate that 2 billion to 3 billion people around the world receive 70 percent or more of their dietary zinc and/or iron from C3 crops, particularly in the developing world, where deficiency of zinc and iron is already a major health concern.

C4 crops appeared to be less affected by higher CO2, which is consistent with underlying plant physiology, as C4 plants concentrate CO2 inside the cell for photosynthesis, and thus they might be expected to be less sensitive to extracellular changes in CO2 concentration.

The researchers were surprised to find that zinc and iron varied substantially across cultivars of rice. That finding suggests that there could be an opportunity to breed reduced sensitivity to the effect of elevated CO2 into crop cultivars in the future.

In addition to efforts to reduce CO2 emissions, breeding cultivars with reduced sensitivity to CO2, biofortification of crops with iron and zinc, and nutritional supplementation for populations most affected could all play a role in reducing the human health impacts of these changes, said Myers. “Humanity is conducting a global experiment by rapidly altering the environmental conditions on the only habitable planet we know. As this experiment unfolds, there will undoubtedly be many surprises. Finding out that rising CO2 threatens human nutrition is one such surprise,” Myers said.

Other HSPH authors include Antonella Zanobetti, Itai Kloog and Joel Schwartz.

--------

YOU MIGHT ALSO LIKE

Maple Syrup Threatened by Climate Change

8 Foods That California's Drought Will Make More Costly

Climate Change Causes Spike in Coffee Prices 

--------

EcoWatch Daily Newsletter

Aerial assessment of Hurricane Sandy damage in Connecticut. Dannel Malloy / Flickr / CC BY 2.0

Extreme weather events supercharged by climate change in 2012 led to nearly 1,000 more deaths, more than 20,000 additional hospitalizations, and cost the U.S. healthcare system $10 billion, a new report finds.

Read More Show Less
Giant sequoia trees at Sequoia National Park, California. lucky-photographer / iStock / Getty Images Plus

A Bay Area conservation group struck a deal to buy and to protect the world's largest remaining privately owned sequoia forest for $15.6 million. Now it needs to raise the money, according to CNN.

Read More Show Less
Sponsored
This aerial view shows the Ogasayama Sports Park Ecopa Stadium, one of the venues for 2019 Rugby World Cup. MARTIN BUREAU / AFP / Getty Images

The Rugby World Cup starts Friday in Japan where Pacific Island teams from Samoa, Fiji and Tonga will face off against teams from industrialized nations. However, a new report from a UK-based NGO says that when the teams gather for the opening ceremony on Friday night and listen to the theme song "World In Union," the hypocrisy of climate injustice will take center stage.

Read More Show Less
Vera_Petrunina / iStock / Getty Images Plus

By Wudan Yan

In June, New York Times journalist Andy Newman wrote an article titled, "If seeing the world helps ruin it, should we stay home?" In it, he raised the question of whether or not travel by plane, boat, or car—all of which contribute to climate change, rising sea levels, and melting glaciers—might pose a moral challenge to the responsibility that each of us has to not exacerbate the already catastrophic consequences of climate change. The premise of Newman's piece rests on his assertion that traveling "somewhere far away… is the biggest single action a private citizen can take to worsen climate change."

Read More Show Less
Volunteer caucasian woman giving grain to starving African children. Bartosz Hadyniak / E+ / Getty Images

By Frances Moore Lappé

Food will be scarce, expensive and less nutritious," CNN warns us in its coverage of the UN's new "Climate Change and Land" report. The New York Times announces that "Climate Change Threatens the World's Food Supply."

Read More Show Less
Sponsored
British Airways 757. Jon Osborne / Flickr / CC BY-SA 2.0

By Adam Vaughan

Two-thirds of people in the UK think the amount people fly should be reined in to tackle climate change, polling has found.

Read More Show Less
Climate Week NYC

On Monday, Sept. 23, the Climate Group will kick off its 11th annual Climate Week NYC, a chance for governments, non-profits, businesses, communities and individuals to share possible solutions to the climate crisis while world leaders gather in the city for the UN Climate Action Summit.

Read More Show Less

By Pam Radtke Russell in New Orleans

Local TV weather forecasters have become foot soldiers in the war against climate misinformation. Over the past decade, a growing number of meteorologists and weathercasters have begun addressing the climate crisis either as part of their weather forecasts, or in separate, independent news reports to help their viewers understand what is happening and why it is important.

Read More Show Less