DIETARY DING  Wheat and other crops growing in circles surrounded by vents spewing carbon dioxide (similar to the one shown) suggest that high amounts of the greenhouse gas could lower foods' levels of nutrients required for a healthy diet.

In addition to mucking up the planet’s climate, carbon pollution spewed into the atmosphere by burning fossil fuels may also make food less nutritious.

Experimentally elevated levels of carbon dioxide in the air lowered many plants’ levels of iron, zinc and protein — required nutrients for human health. Researchers found these changes in the edible bits of staple grains and legumes such as wheat, rice and soybeans.

Appearing May 7 in Nature, the finding has alarming implications for global health, the authors say. Around 2 billion people already suffer from iron and zinc deficiencies, the authors report, and about the same number get 70 percent of their zinc and iron from these crops.

“That’s a really big deal,” says public health researcher Samuel Myers of Harvard. “If everyone was getting their dietary iron and zinc from fish, this wouldn’t matter much.”