Climate change and extreme weather are taking a toll on crops from corn to coffee, jeopardizing the global food supply.
How big is the problem?
About three-quarters of farmland worldwide is vulnerable to significant climate disruptions, according to Jonas Jägermeyr, a climate scientist and crop modeler with NASA. That’s partly a result of rising heat—the 10 hottest years on record have all occurred since 2014—and partly because that warming makes extreme weather events such as heat waves, floods, and cyclones more frequent and destructive. The number of such events has increased some 400 percent over the past 50 years, causing significant damage to food systems. Climate-related disasters such as hurricanes and wildfires destroy infrastructure like roads and bridges, making it more difficult to transport food to people. They also wreak havoc on farms, wiping out crops and harvests. Droughts can degrade the quality of soil and recurrent floods can wash it away, rendering farmland barren or limiting the quantity and quality of what grows. The insurer Lloyd’s estimates there’s a 50 percent risk of a food “shock”—in which a multiyear period of extreme weather leads to major crop failures, mass starvation, social unrest, and a global recession—in the next 30 years. Saving the food system, says Jägermeyr, is “the challenge of our generation.”
Which crops will be worst hit?
The casualties are wide-ranging. California lettuce crops turned yellow during a July heat wave; olive oil prices have tripled in recent years as heat waves scorched southern Europe; and a drought in Vietnam shrunk the planet’s supply of robusta coffee beans. More worrying is the forecast for corn, which provides a fifth of human caloric intake. Crop yields in the U.S. corn belt will drop 40 percent by late century, a result of rising temperatures and water shortages, according to a University of Connecticut study. That trend will be repeated around the globe; NASA researchers expect corn yields worldwide to drop by an average of 24 percent over the same period. Rice—a staple relied on by an estimated 3 billion people—faces a similar threat. In China, extreme rainfall has reduced yields over the past two decades. India has cut rice exports out of fear of shortages at home. And in California, farmers in 2022 let more than half of the state’s 550,000 acres of rice fields lie fallow after years of drought. “Without the water, we have dirt,” said farmer Matthew Garcia. “It’s basically worthless.” Some food staples, though, could see a short-term boost as a result of climate change.
Which crops might do better?
A 2021 NASA study found that anticipated climate changes could boost wheat yields by 17 percent. That’s because rising temperatures and shifts in rainfall may allow the grain to be grown in areas that were once too frigid, including parts of the northern U.S., Canada, and Central Asia. But those gains are expected to level off by mid-century, and other parts of the world will see sharp declines. Temperature and rainfall are not the only climate change–related factors that affect yields. Higher levels of atmospheric carbon dioxide from human activity increase photosynthesis, resulting in more growth in wheat and certain other crops. But that growth burst is often accompanied by decreased nutrient content, with levels of zinc, iron, protein, and vitamins dropping. “By 2050, hundreds of millions of people could slip below the minimum thresholds of these nutrients needed for good health,” said Harvard researcher Samuel Meyers, “and more than 2 billion already deficient could see their conditions worsen.”
How will climate change affect food prices?
It’ll push them higher. Wholesale food prices have increased 50 percent globally since 1999, due to a combination of factors such as climate change, conflicts like the war in Ukraine, and Covid-era supply chain problems. And rising temperatures alone could cause global food prices to increase by up to 3.2 percent annually by 2035, according to German researchers. Price spikes, food shortages, and hunger—some 333 million people don’t have enough food to meet their dietary needs, more than double the number pre-pandemic—can snowball into other problems, sparking unrest, conflict, and mass migration. There were an unprecedented 12,500 protests worldwide over the cost of food and other essentials in 2022, and a study by South Korean researchers found that rising temperatures and reduced corn yields will increase civil conflict in sub-Saharan Africa by more than 30 percent from 2030 to 2050.
Can food systems be strengthened?
More land could be dedicated to crops. One study suggests 1.5 billion acres of new farmland will be needed to meet demand, nearly the size of two Indias. But that would involve the mass felling of forests, which trap planet-heating carbon, increasing emissions from agriculture. Already, the sector is responsible for about a quarter of global carbon emissions, mostly through deforestation to clear land. Adaptation may be necessary: The State Department has launched an initiative to help some African farmers return to growing traditional, sturdy, and nutrient-rich crops like cassava and millet. And genetic engineering and other biotech techniques can help create staples better suited to our changing climate: a lab at the University of California, Davis has developed flood-resistant rice varieties that are now being grown by 6 million subsistence farmers in India and Bangladesh. There’s some pushback to genetically engineered crops, but Daniel Nepstad, head of the Earth Innovation Institute, a research group, says we have few other options. “Human civilization,” he says, “is at a point where we just have to get a lot more from less.”
In search of sweaty cows
As well as devastating farmers’ crops, climate change is also hurting their livestock. Heat-stressed cows produce less milk, put on less weight, and have higher calf death rates. By century’s end, cattle production losses from heat could hit $40 billion annually—about 10 percent of the value of production of meat and milk from cattle in 2005—according to researchers at Cornell University. To cool their cows, some farmers are installing shade sails and sprinklers, but many small-scale farmers in developing countries can’t afford those investments. Changing cattle breeds could be a lower-cost, long-term fix. Researchers have identified six breeds around the world with a unique “slick” gene, which results in shorter hair and more active sweat glands, helping to keep them from overheating. Some farmers in the U.S. and Canada are now crossbreeding those slick animals with their dairy cows. The hotter it gets, said Peter Hansen, an animal scientist at the University of Florida, “the more important the [slick] gene is going to be.”
