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Climate change can affect nutrient content of crops, harming human health

Elevated carbon dioxide levels may lead to reductions in the nutrients in common crops such as barley, wheat and rice, increasing malnutrition.

Past experiments have shown that wheat, rice, barley, and other related crops end up with less iron and zinc in them if they are grown in environments with high levels of carbon dioxide. So, if we put more carbon dioxide in our atmosphere, that’s likely to might make our crops have less of these important nutrients. But how much would that actually affect our health?

Stanford researchers attempted to answer that question in a paper published in PLOS Medicine in 2018, which was recently highlighted by Stanford News as part of a series exploring the connections between our health and the health of our planet.

In the Stanford News article, Eran Bendavid, MD, an associate professor of medicine and co-author of the paper, explained how zinc and iron can affect health:

Zinc is critical for the immune system and zinc deficiency makes pneumonia, diarrheal illness, malaria more difficult for the body to combat. Iron deficiency has all sorts of manifestations, from lethargy and feeling ill to broader effects, like worse performance in school.

Adding up the days people might lose to disability, disease or death as a result of carbon-dioxide-induced reductions of zinc and iron in crops, the researchers estimated there would be approximately 125.8 million years of healthy life lost globally from 2015 to 2050 if emissions continue relatively unabated. In other versions of this high-carbon-dioxide future, they took into account the potential influence of health care interventions, such as nutrient supplementation and prevention and treatment for malaria, pneumonia, and diarrhea. The researchers found that all of these combined could prevent 26.6 percent of those lost years.

However, a scenario that avoided that level of carbon dioxide emissions in the first place — specifically curbing emissions in accordance with the Paris Agreement’s goal to remain within 2 degrees Celsius of pre-industrial levels — resulted in 48.2 percent fewer years lost.

People in Southeast Asia and Africa are already disproportionately affected by zinc and iron deficiencies and the researchers found they would be the hardest hit by further reductions in crop nutrition. That being said, this could be a significant health issue for people all over the globe, emphasized David Lobell, PhD, professor of Earth system science in the School of Earth, Energy & Environmental Sciences and co-author of the paper:

Even in a world that is getting more and more food secure, malnutrition would be among the biggest — if not the biggest — health effects of climate change.

Photo by kangbch

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