Humanity’s food system is under siege by climate change: Coffee and wheat are threatened, droughts could pose a disaster for arable land, and as temperatures rise, agriculture will have to shift north, where the soil quality is much poorer and limits yields. If this sounds like enough agricultural horrors, there’s more! Rising carbon-dioxide levels are actually making plants less nutritious.
The story begins in 1998 with a mathematician and then–Arizona State University Ph.D. student named Irakli Loladze. While studying for his Ph.D. at Arizona State University, he met biologists who found that they could make algae grow faster by shining light on them — but that the zooplankton feeding on them were, oddly, struggling. The scientists’ hunch? That the algae had less nutrient content but more sugar, what Politico calls the “junk food effect.” Loladze realized that this problem could be bigger, and that it could harm crops essential to the human diet and nutrition. As it turns out, it has. Plants are getting too much carbon dioxide.
At the time, Loladze found that there was remarkably little research into the effect of rising carbon-dioxide levels on plants. But he read all the studies he could, and everything pointed to the “junk food effect.” What does it mean? As he explains to Politco, it’s “the greatest injection of carbohydrates into the biosphere in human history — [an] injection that dilutes other nutrients in our food supply.”
In 2014, he published a paper that examined 130 varieties of plants and found that the concentration of calcium, magnesium, potassium, zinc, iron, and other minerals dropped an average of 8 percent. This summer, other researchers published a study in which they estimated that by 2050, 150 million people could be at risk of protein deficiency, and that 1 billion mothers and 354 million children live in countries where dietary iron could significantly drop. The potential nutritional issues are particularly grave in developing countries.
It’s commonly believed that fruits’ and vegetables’ nutritional contents have dropped because the higher-yielding crops that are favored are less nutritionally dense. That increased carbon dioxide is making plants less nutritious is very far off the radar. A plant physiologist named Lewis Ziska, who’s also researching the problem, expressed concern that it isn’t being met with urgency, telling Politico, “We’re falling behind in our ability to intercede.” New breeds of plants can take, he says, 15 to 20 years to get into fields. Only over the last few years, with the publication of a study in Nature, has the issue received real attention. It doesn’t help that you can’t really perceive this the way you can, say, hurricanes causing historic floods. Vitamins and minerals aren’t visible, but they’re essential.