Eating in a Warming World

carrot soup

For years, scientists have tested how carbon dioxide (CO2) levels affect crops, including whether CO2 affects how fast and tall plants grow, and what the nutritional value is of the harvested crops under study.

It’s not hard to imagine that a warming climate will affect the food supply. Hotter weather and more humidity means more insects. Changing rain patterns mean more droughts, fires, and floods. More frequent and more intense storms will undoubtedly have effects on growing crops and raising livestock. But rising temperatures will also affect the food itself, causing staple crops like rice, wheat, corn, and soy to lose nutritional value because of increased levels of carbon dioxide in the atmosphere. 

While a drop in food nutrition may be scary, it’s not a change that is set in stone. Regenerative agriculture provides interconnected solutions: restored soils grow healthier plants while also drawing down carbon in the atmosphere. Drawing down carbon prevents dangerous warming and reduces risks to crops—both from extreme weather and reduced nutrition.

The Science Behind It

One of the first things we learn in biology class is that people breathe in oxygen and breathe out CO2, but plants “inhale” CO2 and “exhale” oxygen during photosynthesis. While an increasing amount of CO2 is bad for many natural processes and for people, it’s actually good for crops—to a limit, of course.

This year, scientists conducting a multi-year study of the impact of a warming climate on 18 rice varieties in Japan and China published their findings in Science Advances. They observed averages of a ten percent drop in protein, eight percent in iron, and five percent in zinc, which they also discovered correlates with an accompanying rise in CO2 levels. Several B vitamins also fell between 13 and 30 percent. 

“Overall, these results indicate that the role of rising CO2 on reducing rice quality may represent a fundamental, but underappreciated, human health effect associated with anthropogenic climate change,” the scientists write.

On another note, a 2016 study from NASA’s Goddard Institute for Space Studies showed that staple crops soy, wheat, corn, and rice, grew better at higher temperatures when the CO2 levels in the air were also higher. When the temperatures increased and CO2 stayed the same, crops grew less well. 

Delphine Deryng, the lead author on the NASA study, also confirmed that nitrogen, a main ingredient in synthetic fertilizer used widely on conventionally grown fields worldwide, is itself a major source of greenhouse gas emissions. But, she says, there is no simple solution regarding nitrogen, because it is an essential element for plant growth. 

That leaves scientists and farmers stuck between a rock and a hard place, wondering: Can plants be grown on a large scale without vast use of synthetic fertilizer, and can we afford to risk the Earth as we continue to use it?

“The biggest question is how can we sustain and ensure the soil is still nutrient-rich to produce the crops that we need while reducing emissions,” Deryng says. She explains that regenerative agriculture practices like cover cropping and crop rotation can mitigate farmers’ reliance on high-emissions fertilizers. 

“There are soil-management practices that can compensate for the use of fertilizer, by sequestering carbon from the atmosphere to the soil, using management practices like mixed cropping systems where you mix crops with legumes that can use nitrous oxide to fertilize the soil. [Regenerative agriculture] is a practice that offers win-win solutions,” she says. 

Who Will Be Affected

For those who eat a diverse diet, whether omnivorous or vegetarian, food losing its nutritional value isn’t that concerning. Less protein in rice means you can just eat more protein from other sources. But this becomes an environmental justice issue when you consider the two billion people on Earth who rely on rice as their primary food source, and one billion people who are considered food insecure. Not all people who rely on rice are also food insecure, but staple goods like rice make up a large part of the diet of folks who are regularly hungry.

Deryng explains that those who are already likely to go hungry will be the most affected, while folks who currently have money and access to healthy foods may just rely on vitamin supplements. 

“In developing countries, there’s clearly a need to get enough food on the plate,” she says. “The question is how to ensure people have enough food that is nutritious.”

Eating in a Warming World

To feed the 9.8 billion people on Earth in 2050, the world must increase food production by 70 percent from 2005 levels, according to the United Nations Food and Agriculture Organization. But as food production is rising, so are global temperatures, by 0.13 °C per decade since 1950, now at 0.2°C per decade. 

A 2016 study from the European Geosciences Union shows that if average temperatures rise by 1.5˚C over pre-
industrial levels, corn, wheat, and other crops will be much less affected than if the Earth gets 2˚C warmer. The Paris Agreement of 2016 states that countries should aim for emissions low enough so global temperatures only rise to 1.5 C. 

“The main difference between a 1.5 and 2 degree rise is extreme rainfalls, which will particularly affect regions that are already at the limit of extreme,” Deryng says. “For regions in the tropics that already have a high-temperature climate, they would step into higher levels, which would be fatal to crops, and we see more extreme precipitation patterns and heavy rain that can affect agriculture.”

Some scientists are looking to genetic engineering of crops to solve this problem. Make plants hardier in the face of drought, heat, and CO2, and there will be enough for folks to simply eat ten percent more rice. But we know that’s not the solution, because genetic engineering generally requires increased applications of pesticides and herbicides, eventually resulting in dead soils that won’t be able to grow much of anything.

By looking to regenerative methods to restore soil health and make farming as chemical-free and low-emission as possible, we will be saving lives in the process.  

From Green American Magazine Issue