Heat, not drought, will drive lower crop yields, researchers say

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Climate change-induced heat stress will play a larger role than drought stress in reducing the yields of several major U.S. crops later this century, according to Cornell University researchers who weighed in on a high-stakes debate between crop experts and scientists.

"There is a big divide in this field, and we thought there must be some way to resolve this puzzle," said Ariel Ortiz-Bobea, assistant professor of applied economics and management.

That has major implications for crop management as well as plant breeding.

The researchers used decades' worth of data from government and other sources, and their findings are reported in "Unpacking the Climatic Drivers of U.S. Agricultural Yields," published in Environmental Research Letters. Contributors included Toby Ault, assistant professor of earth and atmospheric sciences; postdoctoral associate Carlos Carrillo; and Haoying Wang, assistant professor of management at New Mexico Tech.

Ortiz-Bobea and his team incorporated information from three sources to develop a statistical crop yield model for six crops: maize, cotton, sorghum, soybeans, spring wheat and winter wheat.

The researchers' analysis revealed that soil moisture alone was the best predictor of year-to-year variations in yield across the past four decades. Harvests were particularly sensitive to drought stress in the middle portion of the growing season.

The team then applied its statistical model to scenarios ranging from mild to severe. The analysis projects that temperature, which the authors interpret as , will be the primary climatic driver of in 2050 and 2100. Under the mildest scenario, yields for the six crops are predicted to decrease by 8% to 19%, relative to a world without change. Under the most severe scenario, the projected yield reductions range from 20% to 48%.

The greatest losses are forecasted for maize and spring wheat, but more resilient such as sorghum, which is half as sensitive to high temperature as maize, will experience less damage.

Co-author Ault noted climate change projections show that many of the food-producing counties in the United States could become drier in the summer even if rainfall increases. In a changing climate, this could motivate farmers to plant earlier, but that approach to adaptation can be thwarted by heavy rains during the late spring, as many regions are experiencing this year.

"The work highlights two major challenges for adapting to a ," Ault said. "First, how do we deal with increases in temperature that through higher evaporation rates could surpass increases in precipitation? And second, how can we start to envision an agricultural system of the 21st century that is equipped to handle the remarkable shifts in seasonality that might occur?"


Explore further

Climate extremes explain 18%-43% of global crop yield variations

More information: DOI: 10.1088/1748-9326 Ariel Ortiz-Bobea et al. Unpacking the climatic drivers of US agricultural yields, Environmental Research Letters (2019). DOI: 10.1088/1748-9326/ab1e75
Journal information: Environmental Research Letters

Provided by Cornell University
Citation: Heat, not drought, will drive lower crop yields, researchers say (2019, June 3) retrieved 21 July 2019 from https://phys.org/news/2019-06-drought-crop-yields.html
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Jun 03, 2019
It was 15 degrees C warmer thoughout most Earth's history, from the: Cretaeous, Triassic, Jurassic eras, with a plethera of PLANT and animal life.

This article is more complete horse crap spouted off by foolish alarmists making energy more expensive for everyone.

Jun 03, 2019
The more actual research is used to answer questions like how global warming will affect crop yields the more it is clear that the costs of destabilising our planet's climate are going to be very high. It is the truth of a climate problem that gives science like this it's prominence, it's research opportunities and funding - no lies could move every leading science agency in the world like we have seen; only a correct understanding of critical climate processess has that power.

Ignorance is not bliss and believing you know better than decades of top level expert advice and turning away from it that is foolish. And given how serious that advice consistently tells us it is, it is dangerously irresponsible for those in positions of trust and responsibility to turn aside from it and deliberately choose alt-science that says what you want it to say - and worse again in the face of an accumulating climate crisis to actively encourage distrust of science in the wider community.

Jun 03, 2019
@Old_C_Code.
It was 15 degrees C warmer thoughout most Earth's history, from the: Cretaceous, Triassic, Jurassic eras, with a plethera of PLANT and animal life.
The 'domesticated' crops/cattle and other flora/fauna that helped build and support our complex civilisation and modern human diet was NOT in existence until relatively recently, mate. Most of the plants were woody/weedy types inedible/indigestible by human; and most of the animals that existed back then all went extinct or 'downsized'. If you want to continue existing as a modern human with the modern cultivated foods/diet/environment that sustains our vast numbers today, you can't just pretend it's ok to have a return to such extremes of temperature and instability of climate patterns as applied back when dinosaurs/plesiosaurs etc reigned supreme. Please think more carefully about what you wish for, @O_C_C, because you just might get it if we don't avert AGW 'tipping point'. Good Luck to us all. :)

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