When kangaroos let one rip, the gas may be offensive to the nose but easy on the planet.

Marsupial toots and burps contain little or no methane, a potent greenhouse gas. A new study suggests that the scanty emissions are thanks to the distinct mix of microbes in the kangaroos’ gut. The study appears March 13 in the ISME Journal, a microbial ecology journal. By sniffing out the microbes responsible for the “green” gas, Australian researchers hope to glean ways of curtailing methane blasts from other grazing animals.

Fumes from farm ruminants, such as cows and goats, account for up to 25 percent of methane emissions per year from human-related activities. Since methane can cause about 20 times as much atmospheric warming as carbon dioxide, curbing methane would help slow global warming.