From wilting wheat to stressed pollinators, US farmers and fishermen see unexpected climate effects
This week, farmers across the midwest are preparing for temperatures to reach 115F (46C) as a heat dome covers the region. After a tricky growing season – that seesawed between drought and unseasonably heavy rains – many midwestern farmers worry the extreme heat will scorch, or at least stunt, their already struggling crops.
To say it’s been a hot summer would be an understatement. According to Nasa scientists, July was the hottest month ever recorded. Off the coast of Florida, surface ocean temperatures soared over 101F, bleaching coral reefs. In Arizona, Phoenix residents sweated through a record 31 consecutive days above 110F. Even animals that spend much of their time in the sky, like birds, struggled to keep cool in the sweltering heat.
Across much of the country, the food system also struggled. In Texas, farmers reported smaller yields as their corn and cotton crops struggled to survive soaring summer temperatures. In Arizona, beekeepers spotted dead honeybees outside hives. Even underwater, off the coast of Long Island, kelp farmers recorded another year of shrinking yields.
As extreme heat scorched the oceans, land and skies, it affected our food system underwater, on the ground and in the air. But the ways that it did so were unpredictable – not every crop suffered, though many certainly struggled, and not every region was affected equally. If there was any takeaway, it may have been that previous scientific models for extreme heat failed to capture the full scope of what heatwaves of this magnitude could cause – and that farmers, fishers and pollinators should be prepared to adapt to an uncertain future.
“It’s really problematic if we use past disasters as the basis for which we plan for the future,” says Erin Coughlan de Perez, a professor focused on climate risk management at Tufts University. “The future is not going to be the same as the past.”
Land: wilting wheat and heat-stressed cattle
Extreme heat can stress many plants, including common crops, causing them to go dormant or to seed, stunting growth and disrupting pollen (and therefore fruit) development. In a study published in Nature’s climate and atmospheric science journal this June, researchers found that extreme heat is now more likely to affect wheat yields in the US and China – a major wheat exporter – than historical precedents suggest.
Extreme heat “that used to happen every 100 years, used to be a really rare, unusual disaster event, is now something that would happen every six years” in the United States, said Coughlan de Perez, the lead author on the paper. When temperatures get too hot (above 27.8C, or about 82F), wheat photosynthesizes more slowly, and when it gets very hot (above 32.8C, or about 91F) enzymes in the plant can start to break down.
Although extreme heatwaves are becoming more common, that doesn’t mean every region has become uninhabitable for every crop. Rather, the types of crops that can survive in different regions are changing. Coughlan de Perez points to data published by the Intergovernmental Panel on Climate Change that shows how different crops are faring across the globe. In Texas and across much of the midwest this year, extreme heat threatened corn, cotton, sorghum and soybean crops, which were only saved by heavy rains late in the growing season. As the climate changes, farmers are considering ways to plant or harvest earlier to take advantage of milder temperatures.
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Farmers Fear ‘Crisis’ on Horizon as Heat Wave Threatens Crops, Animals
