A new estimate by Joint Global Change Research Institute shows that the global livestock methane emissions for 2011 were 11 percent higher than 2006 estimates from the Intergovernmental Panel on Climate Change. This change is due to a number of factors including an 8.4 percent increase in methane emissions from the dairy industry, and a 36.7 percent increase in emissions due to changes in manure management, including the use of anaerobic manure lagoons.
“As our diets become more meat- and dairy-rich, so the hidden climate cost of our food tends to mount up,” Professor Dave Reay from the University of Edinburgh told The Guardian in reaction to the study, which was recently published in Carbon Balance and Management.
“Cows belching less methane may not be as eye-catching as wind turbines and solar panels, but they are just as vital for addressing climate change.”
The concentration of methane in the air has climbed ten times more quickly in the last decade than in the early 2000s. In 2015, methane accounted for about 16 percent of global greenhouse gas emissions.
The study noted that methane gas emissions from livestock have risen most sharply in Asia, Latin America, and Africa, whereas they have slowed in the U.S. and Canada and have declined in Europe. Carbon dioxide, by comparison, accounts for about three-quarters of these emissions.
Methane is far more potent than carbon dioxide as a greenhouse gas, but it persists for less time in the atmosphere. Scientists estimate that methane has a global warming potential of 28, meaning that a ton of methane will absorb 28 times more thermal energy than the same amount of carbon dioxide in the same amount of time.
While much methane gas comes from the dairy and cattle industry and from the breakdown of organic matter in landfills, some experts also point to fracked natural gas as a culprit to rising emissions. Speaking to the Washington Post, Drew Shindell, a professor at Duke University who studies methane emissions, noted that this part of the methane gas story is omitted from the study but nonetheless merits attention.
“I don’t think this clearly lets fossil fuels, in particular the U.S. fracking boom, off the hook for the growth in methane,” he says.
Courts, Congress, and the EPA are currently working on two regulations meant to reduce methane emissions. One rule applies to new natural gas facilities nationwide, while the other concerns natural gas production on federal and Native American land.
In late September, ExxonMobil quietly launched a plan to curb methane leaks from its shale oil and gas operations.
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