World’s wheat supply at risk of a dangerous shock due to heat and drought, study warns

Extreme heat waves and drought due to climate change have the potential to shock the global food supply and send prices soaring, according to a new study.

The research, published Friday in the journal npj Climate and Atmospheric Science, assesses a worst-case scenario in which extreme weather hits two breadbasket regions in the same year, hammering winter wheat crops in both the U.S. Midwest and northeastern China.

Winter wheat is planted in the fall, goes dormant in winter cold, then gets harvested in early summer. The study found that the extreme weather conditions that would push those wheat crops beyond their physiological tolerances are becoming more likely. If such weather affected multiple regions at once — a scenario possible in today’s climate — it could stress the global food system in dangerous ways.

Erin Coughlan de Perez, the study’s lead author and a climate scientist and associate professor at Tufts University, said the research was meant to show political leaders and disaster responders the degree to which a critical crop is under threat, so that they can prepare accordingly for such a crisis.

“We’re suffering from a failure of imagination in terms of what this could look like,” Coughlan de Perez said. “The whole point of imagining these serious consequences — we could take action to prevent them and build a more resilient system.”

Already, climate change is disrupting food production across the globe. The Horn of Africa, for example, suffered several years of drought beginning in 2020 that killed livestock and wiped out crops. The World Weather Attribution Network determined climate change was responsible for that drought, which left more than 4 million people in need of humanitarian assistance.

This year, late rain in China’s largest wheat-growing province, Henan, is complicating efforts to harvest grain already damaged by wet weather, Reuters reported.

In the new study, Coughlan de Perez and her collaborators ran climate models for the Midwest and northeastern China, then compared the results with known physiological tolerances of the winter wheat grown in those regions.

High spring temperatures can both slow down wheat’s growth and also cause key enzymes to break down within the plant.

The climate models showed that heat waves that in 1981 were expected to affect the Midwest in only 1 out of 100 years are now likely every six years. In northeastern China, a 1-in-100 year heat wave is now expected to happen every 16 years.

Heat that severe could cause crop failures.

“Physiologically, if we get heat waves that are unprecedented and bigger than things that we’ve seen in the past, this can be devastating for wheat crops,” Coughlan de Perez said. She added that these two key agricultural areas have never experienced temperatures as high — or damaging — as the climate models say is possible.

“Places that have not recently experienced an extreme event or disaster are places that probably aren’t preparing for one,” she said.

Weston Anderson, an assistant research scientist at the University of Maryland and NASA who specializes in climate impacts on food security, said risks to crucial crops are mounting as the world continues to warm.

The new research offers “a solid and sound way to evaluate threats to our food system that are outside the range of the historical record,” said Anderson, who was not involved in the study.

Although the climate models used in the research did not find a strong connection between heat wave patterns in the Midwest and northeastern China, Coughlan de Perez said it’s possible that such events could overlap in the same year.

That would cause wheat supply to crater and prices to rise. China produced about 17% of the world’s wheat in 2022. The U.S. produced about 6%, much of it from the Midwest, according to the Department of Agriculture.

Imports of wheat are critical for nutrition in many countries. That reality became especially clear during the Russian invasion of Ukraine early last year, which disrupted wheat exports from both countries. Together, they were responsible for about a third of global wheat exports. Prices soared, giving rise to fears about imminent hunger and starvation in many African and Middle Eastern countries that rely on those wheat supplies. The worst consequences of the wheat crisis were averted, however, when the warring countries reached a deal that allows Ukraine to export grain.

The new study is far from the first to warn about climate change’s threat to our food supply. The recent U.N. Intergovernmental Panel on Climate Change’s synthesis of climate impacts, its sixth such report, predicts that the risk of hunger will increase over time. The varied impacts of climate change could hamper the production of staple crops like rice, wheat, soybeans and corn, and the chance of simultaneous crop failures will rise, the report says.

However, other recent studies suggest certain levels of global warming could actually increase overall global wheat yields, according to Anderson. That’s because climate change could shift the regions where wheat can be grown, and increases in carbon dioxide could increase photosynthesis and production. But bust years are also becoming more likely, the same studies suggest.

Still other research suggests that some growers’ efforts to improve wheat breeding may not keep up with how fast the climate is warming.

“We should be considering these sorts of threats and the possibility that extreme climate events are leading to more frequent shocks on a global scale, even for these crops where we expect average yields to be increasing,” Anderson said.