High-yield farming may have softened global warming impacts
Advances in high-yield agriculture may not only have helped to feed the planet, but may also have helped to slow global warming by processing over half a trillion tons of carbon dioxide, say researchers at Stanford University.
The yield improvements in existing agriculture have reduced the need to convert forests to farmland, a process that typically involves burning of trees and other plants, which generates carbon dioxide and other greenhouse gases.
Researchers compared actual data on emissions with hypothetical scenarios in which the world’s increasing food needs were met by increase farmland rather than increased yields of the ‘Green Revolution’.
Results suggest that if not for increased yields, additional greenhouse gas emissions from land clearing could have equalled a third of total emissions since the Industrial Revolution in 1850.
The researchers also calculated that for every dollar spent on agricultural research and development since 1961, emissions of the three principal greenhouse gases – methane, nitrous oxide and carbon dioxide – were reduced by the equivalent of about a quarter of a ton of carbon dioxide – a high rate of financial return compared to other approaches to reducing the gases.
“Our results dispel the notion that modern intensive agriculture is inherently worse for the environment than a more ‘old-fashioned’ way of doing things,” said lead author Jennifer Burney, lead author of a paper describing the study.
Burney, a postdoctoral researcher with the Program on Food Security and the Environment at Stanford, said agriculture currently accounts for about 12 percent of human-caused greenhouse gas emissions.
Although greenhouse gas emissions from the production and use of fertilizer have increased with agricultural intensification, those emissions are far outstripped by the emissions that would have been generated in converting additional forest and grassland to farmland.
“Every time forest or shrub land is cleared for farming, the carbon that was tied up in the biomass is released and rapidly makes its way into the atmosphere – usually by being burned,” she said. “Yield intensification has lessened the pressure to clear land and reduced emissions by up to 13 billion tons of carbon dioxide a year.”
“When we look at the costs of the research and development that went into these improvements, we find that funding agricultural research ranks among the cheapest ways to prevent greenhouse gas emissions,” said Steven Davis, a co-author of the paper and a postdoctoral researcher at the Carnegie Institution at Stanford.
The authors also note that raising yields alone won’t guarantee lower emissions from land use change.
“It has been shown in several contexts that yield gains alone do not necessarily stop expansion of cropland,” co-author David Lobell said. “That suggests that intensification must be coupled with conservation and development efforts.
“In certain cases, when yields go up in an area, it increases the profitability of farming there and gives people more incentive to expand their farm. But in general, high yields keep prices low, which reduces the incentive to expand.”
The researchers concluded that improvement of crop yields should be prominent among a portfolio of strategies to reduce global greenhouse gases emissions.
“The striking thing is that all of these climate benefits were not the explicit intention of historical investments in agriculture. This was simply a side benefit of efforts to feed the world,” Burney noted. “If climate policy intentionally rewarded these kinds of efforts, that could make an even bigger difference. The question going forward is how climate policy might be designed to achieve that.”