It’s tough out there for a hungry grasshopper on the Kansas prairie. Oh, there’s plenty of grass to eat, but this century’s grass isn’t what it used to be. It’s less nutritious, deficient in minerals like iron, potassium and calcium.
Partly due to that nutrient-deficient diet, there’s been a huge decline in grasshopper numbers of late, by about one-third over two decades, according to a 2020 study. The prairie’s not hoppin’ like it used to — and a major culprit is carbon dioxide, says study author Michael Kaspari, an ecologist at the University of Oklahoma in Norman.
Atmospheric carbon dioxide is at its highest in human history. That’s probably fine for plants like the grasses the hoppers munch. They can turn that atmospheric carbon into carbohydrates and build more plant — in fact, plant biologists once thought all that extra carbon dioxide would simply mean better crop yields. But experiments in crops exposed to high carbon dioxide levels indicate that many food plants contain less of other nutrients than under carbon dioxide concentrations of the past. Several studies find that plants’ levels of nitrogen, for example, have fallen, indicating lower plant protein content. And some studies suggest that plants may also be deficient in phosphorus and other trace elements.
