Global Warming Increases Chance of Widespread Corn Shortages

(CN) — Rising global temperatures will lead to considerable spikes in the variability of annual corn yields by the end of the century, increasing the likelihood of simultaneous low outputs across several high-producing regions, a new study from the National Academy of Sciences finds.

Corn, the most widely grown crop on the planet, is used in industrialized foods, cooking oil, livestock feed and even automobile fuel.

The report, published Monday in the Proceedings of the National Academy of Sciences, examines how climate change will affect global corn yields and how the resulting volatility could trigger price hikes and global shortages.

“Previous studies have often focused on just climate and plants, but here we look at climate, food and international markets,” said lead author Michelle Tigchelaar, a University of Washington postdoctoral researcher in atmospheric sciences.

“We find that as the planet warms, it becomes more likely for different countries to simultaneously experience major crop losses, which has big implications for food prices and food security.”

The findings come in the wake of a recent University of Washington study investigating the nutritional value of rice under global warming.

While rice is generally used domestically, corn is traded internationally. The United States, Brazil, Argentina and Ukraine produce 87 percent of global exports — China primarily grows the crop for domestic use.

The probability today that all four of the top exporting nations would simultaneously experience a bad year, in which yields shrink to at least 10 percent below normal, is nearly zero.

However, the report shows that by limiting warming to 3.6 degrees Fahrenheit above preindustrial global averages — the primary objective of the Paris agreement — the risk grows to 7 percent.

Warming of 7.2 degrees Fahrenheit — which the planet will reach by the end of the century if greenhouse gas emission levels are not curbed — would lead to an 86 percent chance that the four corn exporters would simultaneously experience a bad year.

This suggests that episodes like the 2003 heat wave that ravaged crops in Western Europe will be more likely to coincide with production downturns in other regions.

“Yield variability is important for determining food prices in international markets, which in turn has big implications for food security and the ability of poor consumers to buy food,” Tigchelaar said.

The team inputted global climate projections into corn growth models to verify previous findings showing that elevated temperatures will hurt maize crops.

“When people think about climate change and food, they often initially think about drought,” Tigchelaar said, “but it’s really extreme heat that’s very detrimental for crops.

“Part of that is because plants grown at a higher temperature demand more water, but it’s also that extreme heat itself negatively affects crucial stages in plant development, starting with the flowering stage and ending with the grain-filling stage.”

The findings demonstrate that warmer temperatures will dramatically reduce average maize yields in sub-Saharan Africa, Eastern Europe and the Southeastern United States.

“Climate change will cause unprecedented volatility in the price of maize, domestically and internationally,” said co-author David Battisti, a professor of atmospheric sciences at UW.

The report did not consider precipitation changes, as they are more difficult to predict, and projections show that variations will be small compared to natural changes in yearly rainfall. It used temperature swings on the level of what occurs today, though some models predict temperatures will become more volatile with increased warming.

“We took a conservative approach and assumed the weather will be the same, only acting on top of an overall warmer climate,” Battisti said.

The study supports efforts to pursue new agricultural technology and techniques to protect food security for an expanding global population.

The team notes that its results “underscore the urgency of investments in breeding for heat tolerance.”

The research was funded by the Tamaki Foundation, a Seattle-based nonprofit founded in 1988.

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