Does Higher Atmospheric CO2 Content Threaten Human Health?
The risk isn't anything we haven't seen or can't counter.
Last month National Public Radio reported that “As Carbon Dioxide Levels Rise, Major Crops are Losing Nutrients.” It cited Harvard’s Sam Myers as saying this could be a big problem for someone “just barely getting enough of that particular nutrient.” He added that it “would [be] more harmful when that person gets a meaningful amount of a nutrient from the crop that’s losing nutritional value.”
Nutrient density does decline in some crops as carbon dioxide increases in the air. But does that pose a risk? And if so, what can we do about it?
The Distinction: Content Versus Concentration
Dr. Craig Idso, of the Center for the Study of Carbon Dioxide and Global Change, explains that the decline in nutrition is generally small. It usually amounts to less than 5 percent.
Further, reduced nutrient concentration doesn’t always occur. Where it does, it isn’t uniform. Different varieties of the same crop respond differently. Some lose some nutritive value under enhanced CO2, but others gain it.
It’s also important to distinguish nutrient content from nutrient concentration. Though concentration falls in some varieties, content almost always increases.
“The increase in roots,” Idso explains, “allows the plants to explore more soil and gather a greater nutrient content that is then distributed among the CO2-enhanced biomass, where it is sometimes diluted because the growth enhancement is so large. When it is diluted, one can view it in another light, that the plants become more efficient in using nutrients, i.e., their nutrient use efficiency increases.”
Usually, taking a multivitamin supplement or eating an extra bite or two would make up for reduced nutrient concentration. Because more carbon dioxide raises crop yields, foods become less expensive, making the extra bites easy to afford.
Countering the Risk
Further, a slight change in the quantity or mix of fertilizers applied to soil can restore full nutrient concentration.
Does rising atmospheric carbon dioxide pose a risk to nutrition, then?
Well, yes. But it’s a small risk that can be overcome easily. One could eat slightly more of the affected crops or other sources of the same nutrient. Or one could take a multivitamin supplement. Or farmers could use a bit more or slightly different fertilizer.
What is not sensible is assuming that human beings, who have made all kinds of adjustments through the ages, will fail to take such steps to counter the risk.
Calvin Beisner, Ph.D., is founder and national spokesman of The Cornwall Alliance for the Stewardship of Creation.