A new study published in the journal Science reveals that over half of U.S. landfills are significant sources of methane emissions. This finding marks the largest assessment to date of methane from landfills, which is the third-largest source of methane emissions in the United States.
Led by the research group Carbon Mapper, along with collaborators from NASA Jet Propulsion Laboratory, Arizona State University, University of Arizona, Scientific Aviation, and the Environmental Protection Agency (EPA), the study highlights the critical role landfills play in climate change.
The research found that approximately 52 percent of landfills surveyed had observable methane emission point sources. In comparison, only 0.2 to 1 percent of sites in the oil and gas sector are classified as \"super-emitters,\" which are defined as sources releasing at least 100 kilograms of methane per hour.
Notably, 60 percent of the large-emitting landfills experienced methane leaks that persisted for months or even years, whereas methane leaks in the oil and gas sector were typically short-duration events. Dan Cusworth, a scientist at Carbon Mapper and the study's lead author, emphasized the importance of identifying these persistent leaks as a swift strategy to reduce emissions.
\"Addressing these high methane sources and mitigating persistent landfill emissions offers a strong potential for climate benefit,\" Cusworth stated.
While oil and gas have been the primary focus of emerging regulations and voluntary programs in the U.S. and Europe, the study suggests that landfills are now a crucial target for methane reduction efforts. With the advent of more aerial and satellite surveys, regulators will gain the ability to accurately measure, quantify, and address methane emissions from landfills.
Previously, emissions estimates relied on model-based approaches and handheld methane sensors, which provided a less comprehensive understanding. The study found that the EPA's greenhouse gas reporting system underestimated landfill methane emissions by a factor of 1.4.
In 2021, methane accounted for 12 percent of all greenhouse gas emissions from human activities in the United States, underscoring the significance of targeting this potent greenhouse gas in climate change mitigation strategies.
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Surveys show U.S. landfills are major source of methane emissions
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