Cattle ranching and rice farming are the most plausible sources of rising methane gas emissions, says a new report led by the French Laboratoire des Sciences du Climat et de l’Environnement (LSCE).
The researchers “reported that methane concentrations in the air began to surge around 2007 and grew precipitously in 2014 and 2015,” says Reuters. The study pointed to the expansion of cattle herds from 1.3 billion head in 1994 to 1.5 billion in 2014, as well as to an increase in rice cultivation across Asia.
Cow flatulence, burps and manure are such a large source of methane that California passed a law earlier this year to regulate them. Rice paddies, for their part, host microbes that generate the gas.
About 60 percent of methane comes from human activities, including fossil-fuel extraction, but mostly from agriculture; the rest is emitted from natural sources like wetlands. The focus in climate-change debates is often on carbon dioxide, which is more prevalent in the atmosphere than methane. But methane traps 28 times more heat.
“When it comes to methane, there has been a lot of focus on the fossil fuel industry, but we need to look just as hard, if not harder, at agriculture,” said Robert Jackson, a co-author of the paper and a professor in Earth System Science at Stanford University.