Global methane emissions have been increasing at an unprecedented rate in the past two decades, and now it looks as though livestock may be primarily responsible for the alarming upswing.
A major climate report, published last week, reveals that we have been seriously underestimating how much methane livestock produce. Specifically, the study found that emissions in 2011 were 11 percent higher than projections made by the Intergovernmental Panel for Climate Change (IPCC).
Right now, the majority of methane emissions are created from fossil fuel production and transportation, but these findings add to a growing body of evidence that suggests we have been significantly underestimating the role of agriculture in methane emissions.
When we hear about global warming most of us think of CO2, but methane doesn't get enough credit. Methane is roughly 30 times more potent than CO2 as a heat-trapping gas. And scientists estimate that over the course of a century, "global-warming potential" of methane is 28 times greater than for CO2.
Ruminant animals, like cows, produce methane through enteric fermentation, which is a unique digestive process that allows livestock to consume plant material. Unfortunately, the process also involves belching or farting out methane. And while one fart of methane may not seem like much, over time it adds up.
In fact, according to the lead author of the study, Julie Wolf, livestock "may be the biggest contributor to increases in the atmospheric budget over recent years."
While methane emissions from agriculture have slowed in the U.S. and declined in Europe, they have increased dramatically in developing regions like Asia, Latin America and Africa.
Livestock is one of the fastest growing agricultural subsectors in these developing regions, and is primarily due to "population growth, urbanization and increasing incomes."
"In many regions, livestock numbers are changing, and breeding has resulted in larger animals with higher intakes of food," said Wolf.
"This, along with changes in livestock management, can lead to higher methane emissions."
And that is exactly what climate scientists have been observing. Since 2007, the concentration of methane in the atmosphere has climbed 10 times faster than the previous decade.
Eating less meat and dairy will certainly help, but finding a way to reduce methane emissions from agriculture will have a much greater impact. Currently, scientists are looking at feed supplements that inhibit methane production. A recent experiment found that adding a supplement to cow feed reduced methane emissions by 30%, and there is some evidence to suggest that adding seaweed to cow feed also limits methane emissions from enteric fermentation.
While these experiments are promising, if we do not find a solution soon, global temperatures could exceed the Paris agreement's goal by an additional two degrees, according to the authors of the paper. Such an increase would be detrimental and would jeopardise our ability to address climate change in the future.