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Will climate change cause food sources to dwindle?

older man harvesting cherries

Record-breaking floodwaters engulfed the plains of Nebraska in March. As-yet-untold crops, livestock, and farmlands were lost in the disaster. The Nebraska Department of Agriculture estimates that the value of the lost crops and livestock will surpass $800 million.

Nebraska’s main crops include cattle, corn, soybeans, wheat, and dry beans. The state’s estimate of losses does not include the cost of lost livelihood to the many farmers who don’t know when they will be able to farm their land again.

While the floodwaters in the Plains have begun to recede, the National Oceanic and Atmospheric Administration warns that historic, widespread flooding, worsened by above-average snowfall and spring rain, will continue through May.

The heat waves, droughts, wildfires, and floods that have become the norm in recent years have serious implications for the food supply:

  • Extreme heat, floods, and droughts can damage crops and make yields smaller.
  • Warmer winters cause premature budding that leads to crop loss.
  • Heat waves threaten livestock, too. Continued exposure to extreme heat can make animals more likely to get disease and cut fertility and milk production.
  • Specific crops face specific dangers. A new study, for example, has found that climate change has helped to spread a fungus that could destroy 80% of banana crops.
  • Higher rainfall from spikes in humidity in a warmer climate leads to loss of soil carbon, which is crucial for plants.

“We can expect to see more of this,” says Peter de Menocal, PhD, director of the Center for Climate and Life at Columbia University.

Experts appear certain these changes, if not addressed, will add up to less food and higher prices in U.S. grocery stores by the middle of this century. Some of the effects may begin soon or have already begun. But they are already affecting U.S. farmers, who have been forced to adapt to the new growing environment.

Changing weather has caused problems in other countries that have an effect on the U.S., too. A years-long drought in Syria that eventually caused that country’s agricultural industry to collapse was among the many things that sparked the civil war that began in 2011.

“Our ability to grow food is not unlimited,” says Lewis Ziska, PhD, a plant physiologist at the U.S. Department of Agriculture (USDA). “The one issue that I probably have the most concern about is the issue of food security and its role in the destabilization of countries around the world.”

A Growing Challenge

U.S. famers have already been grappling with the uncertainty that has become the new normal when it comes to weather.

That may mean planting as early in the year as possible in order to harvest before the heat waves of midsummer and the torrential downpours of the fall. A nationwide drought in 2012 that affected more than two-thirds of U.S. counties led the federal crop insurance program to make $14.5 billion in payments to farmers.

“It really is a great threat,” says Montana farmer Nate Powell-Palm.

He lost his entire crop of garbanzo beans to a heat wave in 2017. “It was like 102 degrees during the flowering period, and the temperature stayed there for weeks,” he recalls. “Any crop that wasn’t planted super early was just decimated. These kinds of shocks can spiral farms into bankruptcy.”

Powell-Palm took out a line of credit to tide him over till the next year. Luckily, the next year -- a good one -- he paid back the debt.

“Young farmers like me, we’re terrified of debt,” he says. “Farming is enough of a risk just with the market prices, and now you start adding weather events to that.”

The workaround for all this uncertainty, he says, is to plant crops as early in the year as possible. But spring is unpredictable, too. Bozeman, MT, usually gets about 5 inches of snow in February, Powell-Palm says, but it got 27 inches this February. In snowfall that dense, farmers frequently lose newborn calves because they can’t find them in time to bring them in out of the snow.

That much snowfall can also mean soil that’s too frozen or too wet for planting in early spring -- no matter how eager farmers are to get started. Online guidance for farmers in Nebraska reads, “If you're putting a log chain or tow strap in the tractor cab just in case you get stuck, even you know it’s too wet.”

Changing Soil

Besides the changing weather, the soil itself is changing, too. Soil stores carbon, a nutrient that keeps it healthy and fertile for food production. Carbon and other crucial compounds in the soil also help prevent erosion -- the gradual destruction of the soil. Both floods and winds after droughts can erode the soil and sap its nutrients.

“The risk of floods is a gradual loss of the soil,” says Mike Rivington, PhD, who researches land use at the James Hutton Institute in Scotland. “So it’s a double-edged sword when you get both wind erosion and rain-based erosion.”

Carbon released from the soil into the air accounts for about one-third of the increase in carbon in the atmosphere over the last 150 years. The transfer of carbon adds to rising temperatures and makes soil that’s less fertile and more likely to erode.  

Research shows that many farmers across the Corn Belt in Midwestern states are shifting their farming practices to prevent erosion and keep soil healthy. Some have stopped or significantly reduced tilling, which mixes up the soil as a way to control weeds and pests, among other benefits, but also promotes erosion and removes essential nutrients from the soil. Many Corn Belt farmers have also started to plant “cover crops,” which are planted after the cash crop to prevent erosion, weeds, and pests and maintain soil quality.

“We are seeing a recognition at the farm level that this is not their father’s climate. Farmers are seeing things that are different from what they’ve seen before,” says Ziska of the USDA.

More CO2, Fewer Plant Nutrients

These changes in the soil and the air, research finds, are changing the very chemistry of the plants people rely on for food. More CO2 in the atmosphere is, in fact, good for plant growth. But size isn’t everything when it comes to the value of a plant.

“Growing crops at elevated CO2 decreases their nutritional value,” says Donald Ort, PhD, the Robert Emerson professor of plant biology and crop sciences at the University of Illinois. “Protein tends to go down as well as micronutrients like calcium and magnesium.” As these nutrients go down, starch rises in rice, wheat, and other crops.

Researchers don’t know for sure why this may be, but they have theories. “With higher CO2, it’s thought that plants become less nutritious because they put more energy into their growth and not as much into the development of the parts of the plant that we eat,” says Michelle Tigchelaar, PhD, a climate scientist at the Stanford University Center for Ocean Solutions.

But some research suggests that the combined effects of CO2 and rising temperatures on crops will offset each other. In one study, researchers grew soybeans in a greenhouse where temperatures and CO2 levels reflected those predicted for 2050. The heat, they found, boosted the nutritional value of the plants while the CO2 lessened it. Also, the heat stunted plant growth, while CO2 bolstered it. The results, the study authors concluded, was that crops in 2050 may not be so different from those grown today.

The Soil Science Society of America, which describes itself as a progressive group focused on soil sustainability, says that while most areas will have agricultural losses from climate change, some will not. “Some regions and crops will benefit, most will not,” the group says.

Those closest to the issue -- i.e., farmers -- are less likely to be convinced climate change is real or that humans are to blame. A 2014 study from Purdue University found that while more than 90% of scientists and climatologists believe climate change is real and more than half said humans were the cause, only 66% of corn growers recognize climate change as real. Only 8% of farmers said humans were the cause of climate change.

What’s to Be Done

While ideological divisions over climate change will continue, those who see it as a threat are already exploring ways to adapt. Simply cutting carbon emissions to halt temperature rise is no longer enough to stem the tide of climate change.

“There will be changes no matter what we do. Even if we were to go completely fossil fuel-free tomorrow, we will still have more warming. It’s inevitable. It’s already baked in,” says Jonathan Patz, MD, director of the Global Health Institute at the University of Wisconsin-Madison. “We need to be prepared.”

One way to prepare is to change farming practices. “Organic farming is the complete package as far as addressing climate change,” says Powell-Palm. He is an organic farmer himself, but scientific research backs up what he says. A 2017 side-by-side comparison of the soil composition of organic farms and conventional farms found that organic farms pull significantly more carbon out of the air and into the soil than conventional farms do.

"If we don’t cut greenhouse gas emissions, we are in very serious trouble." Mike Rivington, PhD, land use researcher at the James Hutton Institute in Scotland

But while alternative farming practices can preserve the soil in the long run, they may not be cost-effective for farmers in the short term. For that reason, not all farmers are eager to take them up. New farming methods also may not address the changing chemistry of plants, so researchers are exploring ways to address that issue, too.

Beyond being profitable for farmers, however, is the larger question of whether organic food can be made in large enough quantities, and at affordable prices, to feed the world’s growing population. Two recent studies made the claim that it is possible, but both would require most of the people on earth to become vegetarian, as organic vegetables are more affordable than organic meat and are easier on the environment.

Still, Ort says, “We’re looking for strategies to adapt plants to the conditions that we know are coming.”

Ort and his team have genetically modified plants to boost crop size by 40%. They are also exploring ways to identify species of plants that are naturally more productive so that genetic modification won’t be the only way to feed the global population. “There’s the possibility to go out and look for natural genetic variation that might be in wild relatives of soybean, or wheat, or rice, and then bring it in by selective breeding rather than by genetic engineering,” he says.

Ultimately, researchers hope that a collection of approaches will address growing food needs in the face of less productive crops. Steps to slow temperature rise will tackle the problem from one side, while adaptation must happen on the other.

“If we don’t cut greenhouse gas emissions, we are in very serious trouble,” says Rivington, “but other tactics must happen together at the same time.” 

By:  | WebMD Health News

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The Ort Lab is supported by many public and private partnerships, including the Bill & Melinda Gates Foundation, the Foundation for Food and Agriculture Research, the UK Government's Department for International Development, the U.S. Department of Energy, and the Advanced Research Projects Agency-Energy.

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