The news about cow burps and farts is worse than we thought (if you ever did think about such things, that is).
According to a new report, the methane emitted from the over 1.5 billion cows worldwide is actually 11 per cent higher than previous estimates from the UN’s Intergovernmental Panel for Climate Change (IPCC). Attributed to the increasing size of cows, along with changes to feeding and manure management practices, the smellier-than-before bovine effluent stand as a major contributor to global emissions and an increasing concern in the fight against climate change, say climate experts.
Researchers with the United States Department of Agriculture, the US Department of Energy and the Joint Global Change Research Institute at the University of Maryland looked into the issue of why, after a half-decade of gradual yearly increases, atmospheric concentrations of methane shot up between 2006 and 2016.
Up until now, that riddle remained unanswered, with potential culprits being either environmental sources like wetlands and peatlands which naturally give off methane — a greenhouse gas which while less prevalent than carbon dioxide is over 20 times more powerful at trapping heat in the atmosphere than CO2 — or human-produced sources such as shale fracking for natural gas or agricultural production, which produces methane both from the flatulence and belching of ruminants like cows and sheep but also from the decaying of organic wastes.
How much methane does a cow produce?
Scientists are still uncertain, but estimates are between 100 and 200 litres per day (with some saying up to 500 litres!) – that’s comparable to the pollution coming from a car. The gas production is a result of the rumination process which involves microbes that help break down the regurgitated food (called cud) and as a by-product produce methane gas. As far as straight-from-the-cow methane goes, it’s the burping more than the gas from the other end that is of concern, along with the methane given off by manure as it decomposes.
The updated account comes from inputing new figures for cattle size (which keeps increasing as agricultural practices advance) along with changes to feed quality and quantity, differences in milk production as well as changes to the management of manure, which now involves greater use of anaerobic decomposition processes that produce more methane than before.
The result is an 8.4 per cent increase in methane from enteric fermentation (the burping and flatulence) and a whopping 36.7 per cent increase in gas production from manure management.
“Just from livestock methane emissions, our revisions resulted in 11 percent more methane in a recent year than what we were previously estimating,” said Julie Wolf, lead author of the study who conducted the research while at the Joint Global Change Research Institute, to the Washington Post. “It’s not the biggest contributor to the annual methane budget in the atmosphere, but it may be the biggest contributor to increases in the atmospheric budget over recent years.”
The researchers say that addressing the agricultural production of methane will be necessary in the fight against global warming. Over the past decade, methane from livestock saw a sharp rise in developing regions in Asia, Latin America and Africa, while lesser increases have come from United States and Canada and actual declines in emissions from Europe.