Landfills produce gas. For those of you thinking about the smell that wafts out of your garbage can every time you open the lid, that probably comes as no surprise.
But what you might not know is that gas — predominantly methane — is a major contributor to climate change. In fact, landfills are one of the top emitters of methane gas, along with natural gas systems and leakage, as well as livestock digestion and manure management.
According to a 2018 report from the National Academies of Sciences, Engineering and Medicine, 18% of U.S. methane emissions come from landfills.
Greenhouse, or climate change-inducing, gases are most commonly associated with carbon dioxide. While methane is shorter-lived in the atmosphere than carbon dioxide, it’s more powerful, according to Indiana University professor John Rupp. It’s actually more than 25 times as effective at trapping in heat, making it a major greenhouse gas.
Methane is produced from a type of bacteria called methanogens, which feed on organic materials that are made up of carbon. Think food waste, cardboard and paper products, even things like plastic bottles, Rupp said — all things that there are plenty of in landfills.
These microbes don’t produce methane at first, according to Gabe Filippelli, a professor of earth sciences at IUPUI.
“But as the landfill ages, the bacteria that produces methane starts to chew away at the trash and give off lots of methane,” Filippelli said. “They can eat almost anything, and they thrive in an environment like a landfill where it’s sealed up and there’s very little oxygen to it.”