A study by a Rutgers professor and a national team shows rising temperatures could reduce crop production
Climate change is putting the global food system at risk, even as farmers try to adapt, according to a study conducted by a Rutgers-New Brunswick professor and other researchers in a national collaboration.
Publishing their findings in Nature, the researchers found that every 1-degree Celsius increase in global mean surface temperature (about 1.8 degrees Fahrenheit) could reduce the world's ability to produce food by 120 calories a person per day, which is about 4.4% of what people eat daily.
"Through hotter temperatures and shifting rainfall patterns, climate change reduces crop yields," said Robert Kopp, a Distinguished Professor in the Department of Earth and Planetary Sciences in the School of Arts and Sciences and an author of the study. "Farmers adapt, for instance, by changing the varietals of crops they plant, but on its own that may not be enough to avoid the damages wrought by a warming climate."
Kopp worked with more than a dozen scholars for eight years on the project through the Climate Impact Lab, a research consortium currently led by the University of Chicago and dedicated to quantifying the effects of climate change. Kopp co-founded the consortium together with Solomon Hsiang of the Stanford Doerr School of Sustainability, also an author of the study, Michael Greenstone of the University of Chicago and Trevor Houser of Rhodium Group, a New York-based independent research group.
The researchers looked at global data from more than 12,000 regions in 55 nations, focusing on crops that provide most of the world's calories: wheat, corn, rice, soybeans, barley and cassava.
Previous studies failed to account for realistic adaptation by farmers, assuming either "perfect" adaptation or none, the researchers said. The new study is the first to systematically measure how much farmers adjust to changing conditions. In many regions, for example, farmers switch crop varieties, shift planting and harvesting dates or alter fertilizer use.
The researchers estimate that adjustments made by farmers can offset about one-third of the losses caused by climate change by 2100 if emissions keep rising. But the rest of the losses will still happen.
"Offsetting climate damages requires faster innovation in agricultural technology," said Kopp, who also is director of the Megalopolitan Coastal Transformation Hub at Rutgers.
The steepest losses occur at the extremes of the agricultural economy: in modern breadbaskets that now enjoy some of the world's best growing conditions and in subsistence farming communities relying on small cassava harvests. In terms of food production capacity from staple crops, the analysis finds yield losses may average 41% in the wealthiest regions and 28% in the lowest income regions by 2100.
The study also found that rice might benefit from warmer nights, but other crops such as wheat, corn and soybeans will likely see declines.
U.S. agriculture will be hit hard, the researchers said.
"Places in the Midwest that are great for growing corn and soybeans now will suffer a lot in a warmer future," said lead author Andrew Hultgren at the University of Illinois Urbana-Champaign. "We might not have a corn belt in the future."
To do the study, researchers examined data signaling how climate change affects crops and how farmers adapt. They collected data on six important crops from around the world, looking at weather, income and irrigation. They used computer programs to find out which weather conditions, including temperature and rainfall, impact crop production the most.
To understand the overall impact of climate change on food availability, they created computer models to predict future changes in crop production affected by climate change and developed a formula to show how temperature changes affect global food production.
The planet is about 1.5 degrees Celsius (2.7 degrees Fahrenheit) warmer than it was before industrial times, Kopp said. Farmers are seeing longer dry spells, heat waves and unpredictable weather that hurt crop yields. By 2050, climate change is expected to reduce global crop yields by 8%, no matter how much emissions change.
The study modeled future crop yields under different warming scenarios. By 2100, global crop yields could drop by 11% if emissions fall to net zero, meaning that the amount of greenhouse gases emitted into the atmosphere is balanced by the amount removed, and by 24% if emissions keep rising.
"We're trying to make sure this isn't our future, even if we can't reduce emissions quickly," said Hsiang of the Stanford Doerr School of Sustainability. "A good climate is essential for productive farmland. If we let the climate get worse, everything else we do is wasted. The land we leave to our kids won't be good for farming."
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