Climate change is making plants less nutritious - that hurts animals who feed on them

From grasshoppers to cows, giant pandas and humans, nutrient dilution in crops will have an impact.

- Ellen Welti

More than one-third of all animals on earth, from beetles to cows and elephants, depend on plant-based diets. Plants are a low-calorie food source, so it can be challenging for animals to consume enough energy to meet their needs. Now climate change is reducing the nutritional value of some foods that plant eaters rely on.

Human activities are increasing atmospheric carbon dioxide levels and raising global temperatures. As a result, many plants are growing faster across ecosystems worldwide.

Some studies suggest that this "greening of the earth" could partially offset rising greenhouse gas emissions by storing more carbon in plants. However, there's a trade-off: These fast-tracked plants can contain fewer nutrients per bite.

I'm an ecologist and work with colleagues to examine how nutrient dilution could affect species across the food web. Our focus is on responses in plant-feeding populations, from tiny grasshoppers to giant pandas.

We believe long-term changes in the nutritional value of plants may be an underappreciated cause of shrinking animal populations. These changes in plants aren't visually evident, like rising seas. Nor are they sudden and imminent, like hurricanes or heatwaves. But they can have important impacts over time.

Plant-eating animals may need more time to find and consume food if their usual meal becomes less nutritious, exposing themselves to greater risks from predators and other stresses in the process. Reduced nutritional values can also make animals less fit, reducing their ability to grow, reproduce and survive.

RISING CARBON, FALLING NUTRIENTS

Research has already shown that climate change is causing nutrient dilution in human food crops. Declines in micronutrients, which play important roles in growth and health, are a particular concern: Long-term records of crop nutritional values have revealed declines in copper, magnesium, iron and zinc.