A new study highlights a lesser-known but serious consequence of the climate crisis for hundreds of millions of people around the world—major nutritional deficiencies that are likely to hit impoverished populations the hardest, as carbon dioxide emissions seriously affect the quality of food crops.

The study, completed by scientists at the Harvard T.H. Chan School of Public Health and published in the journal Nature Climate Change, found that in just three decades, crops being grown around the world will lose many of their nutritional benefits, thanks to the carbon that's expected to have entered the atmosphere by 2050.

Samuel S. Myers, a co-author of the study, explained in an op-ed in The Hill:

Food crops grown at higher carbon dioxide levels have lower amounts of protein, zinc, and iron, all of which are essential nutrients for human health. Specifically, on average, food grown at CO2 levels expected by 2050 will contain 10 percent less protein, six percent less iron, and seven percent less zinc.



This is particularly concerning as over two billion people worldwide are already thought to be deficient in one or more of these nutrients with very significant consequences for their health.

While crops in some parts of the world are likely to be decimated by the climate crisis, as drought, heatwaves, and extreme weather events become more common, even places where food continues to grow will not be spared from the wide-reaching effects of carbon emissions.

"As concentrations of CO2 approach 550 parts per million by midcentury, hundreds of millions of people are likely to become newly susceptible to chronic deficiencies of protein and zinc. And billions more are likely to suffer from a worsening of their existing nutrient deficiencies," wrote Myers.

"In the most tragic of ironies, the poorest, who have been least responsible for elevating CO2 levels, will be most vulnerable to these nutrient losses because their diets are less diverse and generally contain lower levels of iron, zinc, and protein." —Samuel S. Myers, planetary health scientist

With crops growing on a planet with higher-than-ever concentrations of carbon in its atmosphere, about 175 million people—two percent of the Earth's population—will by 2050 be eating food that doesn't provide enough zinc to keep them healthy. 122 million are expected to become protein deficient, and 1.4 million children and women of childbearing age will be at greater risk for iron deficits.

These nutrient deficiencies are expected to compromise children's immune systems, making them more likely to die of diseases like malaria and diarrhea; leave women and babies less likely to survive childbirth; and cause stunted growth in potentially millions of children worldwide.

Myers stressed that while industrialized countries like the U.S. bear the most responsibility for rising carbon levels—emitting 5.14 billion metric tons in 2017, with the Trump administration rolling back regulations aimed at curbing emissions and denying that the climate crisis is largely driven by fossil fuel industries and other human activities—countries that pollute the least will experience the brunt of these health impacts.

"In the most tragic of ironies, the poorest, who have been least responsible for elevating CO2 levels, will be most vulnerable to these nutrient losses because their diets are less diverse and generally contain lower levels of iron, zinc, and protein," wrote Myers.

Out of the 151 countries the scientists examined, those in North Africa, the Middle East, and parts of South and Southeast Asia are likely to experience the worst health effects, with 50 million people in India alone potentially exhibiting zinc deficiency by 2050.

The New Food Economy noted that some have pointed to genetic modification as the answer to increasingly nutrient-poor crops. But the study's authors are clear in their conclusion that world leaders simply need to make strong commitments to lowering fossil fuel emissions.

"I don't feel hopeless about addressing this problem, except that there's so little government support within our country or abroad to really ramp up an international research agenda," Myers told the New Food Economy. "If we were really committed as an international community, then I think this is a problem that could be addressed."