Another Study Confirms What We Found: Landfill Methane Is Being Undercounted and Missed
For decades, landfill methane regulation and policy has been built on estimates. The U.S. EPA uses simplistic models to predict how much methane landfills produce. Based on those assumptions, municipal solid waste landfills emitted approximately 3.7 million metric tons of methane in 2022, making them the third-largest source of methane emissions in the United States. That’s already bad — but there are multiple studies that suggest even those staggering numbers may underestimate the true scale of the problem. Carbon Mapper has already documented persistent methane super-emitters at landfills across the United States. Research published in Science found that measured methane emissions from U.S. landfills were substantially higher than EPA inventories. Our own research, as a campaign at Industrious Labs, found that assumptions about landfill gas collection efficiency have caused the EPA to underestimate emissions nationwide. Now, a new study adds another important piece of evidence by demonstrating that direct measurements can reveal dramatically different emissions than reported inventories.
Researchers at FluxLab at St. Francis Xavier University, with coauthors from Environment and Climate Change Canada (the federal agency responsible for Canada's greenhouse gas inventory) actually measured what was actually escaping into the atmosphere from landfills, and found challenges with what models show. Using direct measurements at 42 Canadian landfills, researchers found that actual methane emissions were, on average, nearly three times higher than what was reported. Overall they found major discrepancies between actual methane measurements and Canada's inventory model. In many colder, drier regions, direct measurements were lower than modeled estimates, and warmer, wetter landfills had higher estimates than modeled.
Rather than concluding inventories are always too high or too low, the researchers reached a more important conclusion: national methane inventories should be informed by real-world measurements, not assumptions alone. The study also included a revelation with immediate implications for regulators. During on-site investigations, researchers consistently found the largest methane emissions coming from active working faces, newly placed waste, leachate wells, manholes, and construction activities. In some cases, methane concentrations during construction activities exceeded the measurement range of the researchers' instruments!
There’s no shortage of proven, cost-effective technologies that are already working at landfills across North America. In fact, we recently spent an hour hearing from some of the leaders in this fast-growing tech sector at our landfill technology showcase! The challenge isn’t lack of solutions – it’s lack of widespread implementation. In the U.S., federal regulations still rely heavily on convoluted formulas and outdated monitoring methods that let huge amounts of methane escape into the atmosphere unaccounted for.
Fortunately, some leading states are moving beyond outdated approaches. California's new landfill methane regulations require monitoring across the entire landfill, including active working faces that were largely overlooked under previous rules. Under the updated rules, landfill operators must use advanced monitoring technologies including drones and other remote sensing tools to investigate large methane emissions and identify leaks that conventional walking surveys can miss. Colorado has also expanded the use of advanced monitoring technologies and strengthened requirements for finding and fixing methane emissions. Other states, including New York, Michigan, and Illinois, are poised to follow as they weigh new standards for landfill operations.
Landfill methane might be invisible, but there’s no reason for it to be unknowable. Regulators and policymakers should be finding ways to embrace this suite of technological solutions, rather than run from them.
