US Landfills Underestimated as Major Source of Climate-Harming Methane, New Study Shows

Methane emissions from US landfills are much higher than previously thought and officially reported, according to the largest measurement survey of landfills to date.

Landfills produce methane when organic waste decomposes without oxygen, and the gas seeps out. Landfill methane causes 20% of human-caused emissions.

Current reporting systems like EPA's miss large methane sources. Average emissions were 1.4 times higher than figures reported to the EPA.

Over half the landfills surveyed had persistent methane plumes, detected over months or years in follow-up flyovers.

Scientists say reducing landfill methane is crucial to meet climate targets, but most US methane policies target the oil and gas industry.