Warming dents corn and wheat yields

CEREAL KILLERBetween 1980 and 2008, climbing global temperatures took millions of tons of wheat off the dinner table, scientists say. Some countries experienced big losses due to weather (red), while in others, wheat production held steady (blue).Images courtesy of Science/AAAS

Set a place at the table for climate change; hotter weather may have already taken a bite out of food crops worldwide.

Farms across the planet produced 3.8 percent less corn and 5.5 percent less wheat than they could have between 1980 and 2008 thanks to rising temperatures, a new analysis estimates. These wilting yields may have contributed to the current sky-high price of food, a team of U.S. researchers reports online May 5 in Science. Climate-induced losses could have driven up prices of corn by 6.4 percent and wheat by 18.9 percent since 1980.

The researchers tracked country-by-country yields of these common foodstuffs over nearly three decades. Harvests of corn and wheat have climbed steadily since 1980 due in part to technological advancements, says David Lobell, a land-use scientist at Stanford University. But based on the team’s statistical analysis, farmers could have produced a lot more food if the weather had been cooler. For corn, global losses amount to millions of tons — about equal to Mexico’s yearly production of the crop. “For every decade of climate change, it sets you back a year,” Lobell says.

CORN ON THE RUN Corn is feeling the heat from climate change, with yields dropping close to 4 percent due to weather-related factors between 1980 and 2008.Images courtesy of Science/AAAS

For reasons still up for debate, temperatures largely held steady in the U.S. over the study period. So Iowa, by and large, doesn’t seem to have lost out. Rice and soybean yields have also proved resilient to rising temperatures so far, the team discovered.

This analysis of the past three decades largely falls in line with what other studies have projected for the coming century, says Andy Challinor of the University of Leeds in England, who studies the impacts of climate on agriculture. With enough complementary analyses, scientists may start to feel more certain about predicting the future of food. Still, when it comes to agriculture, researchers rely on a very murky crystal ball. Humans can, and probably will, adapt to warmer temperatures, switching to hardier crops or developing new technology to keep harvests high.

While it’s far from a prediction, Lobell says his study identifies a number of problem areas that do need attention — not later but now. “If we really invest a lot in the development of crops that can withstand really high temperatures,” he says, “that would potentially change things a lot.”

Even today, food scarcity is a pressing problem, says Navin Ramankutty, a geographer at McGill University in Montreal. As populations climb steeply, putting added pressure on agricultural production, an estimated one in seven people go hungry across the globe.

Found in: Climate Change, Earth, Earth Science, Ecology and Environment

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