Farming Now Worse for Climate than Deforestation

Efforts ... to slow deforestation have delivered some of humanity’s few gains in its otherwise lackadaisical battle so far against global warming.  A gradual slowdown in chainsawing and bulldozing, particularly in Brazil, helped reduce deforestation’s annual toll on the climate by nearly a quarter between the 1990s and 2010.

A new study describes how this trend has seen agriculture overtake deforestation as the leading source of land-based greenhouse gas pollution during the past decade.  While United Nations climate negotiations focus heavily on forest protections, the researchers note that delegates to the talks ignore similar opportunities to reform farming.

“The decline in deforestation over the past decade or two is a success story,” Rob Jackson, a professor at Stanford University’s earth sciences school, said.  He was not involved with the new study.  The deforestation slowdown has, “in large part,” he said, been driven by new forestry rules in Brazil, by the U.N.’s Reducing Emissions from Deforestation and Forest Degradation (REDD) program, which funds forest conservation, and similar policies elsewhere.

The new study, led by the U.N. Food and Agriculture Organization and published in Global Change Biology, quantifies the reductions in climate pollution from the degradation and clearcutting of forests.  Clearcutting most often clears space for agriculture, suggesting agriculture’s indirect climate impacts surpass the impacts of deforestation for timber and other commodities.  The researchers aim to tally those indirect impacts later this year. This paper was an early step in a larger effort to better understand and report on the climate repercussions of how land is used.  “Every year, we’ll have updates,” lead author Francesco Tubiello said.

The study is also a reminder that the burning of fossil fuels remains the main cause of global warming.  Burning fuel produces about four times more climate pollution every year than forestry and agriculture combined — a figure that is growing.

The research shows that the recent climate-protecting gains in forests are being nearly canceled out by efforts to satisfy the world’s growing appetite — particularly its appetite for meat.  Greenhouse gases released by farming, such as methane from livestock and rice paddies, and nitrous oxides from fertilizers and other soil treatments rose 13 percent after 1990, the study concluded.  Agricultural climate pollution is mostly caused by livestock.  Cows and buffalo are the worst offenders — their ruminating guts and decomposing waste produce a lot of methane.  They produce so much methane, and eat so much fertilized feed, that livestock are blamed for two-thirds of agriculture’s climate pollution every year.
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Some countries, particularly India, have been averse to discussing agricultural impacts during U.N. climate negotiations — largely because they fear that the outcomes of such talks could reduce agricultural output and worsen food shortages.  “Poor countries are not going to sit idly by and just impose reductions in food production to meet greenhouse gas reduction targets,” Schwartzman said.

Doug Boucher, the director of climate research at the Union of Concerned Scientists, says agriculture’s climate impacts could be reduced without taking food off tables.  Reducing the overuse of fertilizers, protecting the organic content of soils by changing farming practices, and keeping rice paddies flooded for fewer weeks every season could all contribute to a climate solution, he said.

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