Scientists say methane is leaking from U.S. landfills at higher rates than previously thought

CNN
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Garbage accumulating in landfills is not just an unsightly sight, it is also a climate nightmare, releasing large amounts of methane gas that warms the planet. In the United States, the problem could be much worse than previously thought, according to a new study that measures methane pollution in hundreds of landfills across the country.

Scientists flew over more than 200 landfills across 18 states from 2018 to 2022, in what they say is the largest measurement-based survey of American landfills. Their results revealed that average methane emissions were much higher than those officially reported, according to the institute Stady It was published Thursday in the journal Science.

Methane — an invisible, odorless gas with more than… 80 times more warming power of carbon dioxide in the near term – will be produced from various sources, the largest of which are oil, gas and agriculture. Landfills tend to be a lesser-known source of methane, but they also have a significant impact, estimated at about 20% Global anthropogenic methane emissions.

Landfills produce methane gas when organic waste such as food scraps, paper and wood decompose without oxygen, creating an ideal environment for methane-producing bacteria.

Most U.S. landfills are federally required to measure methane emissions four times a year through walk-through surveys using portable sensors. The accuracy of these surveys can vary, as people tend to avoid areas that are unsafe to walk through, including steep slopes and where trash is dumped, according to the study.

“These types of measurements are not designed to really do anything in terms of emissions, just to detect methane ‘hotspots,’” Daniel Cosworth, lead author and scientist at the nonprofit Carbon Mapper, told CNN.

Estimates of methane emissions from landfills therefore tend to rely on models, not direct measurements – but this means there are potential data gaps. The report noted that advanced monitoring systems that use remote sensing from aircraft, drones and satellites can provide a more accurate and comprehensive picture.

Using airborne imaging spectrometers, scientists detected methane plumes in 52% of the landfills they measured. The report notes that this far exceeds the rate of methane detection in airborne studies conducted for the oil and gas sector.

The results show current reporting systems, such as the EPA Greenhouse Gas Reporting Program The scientist concluded that GHGRP lacks significant sources of methane. The report found that average methane emission rates from landfills were 1.4 times higher than those reported to GHGRP.

The study also found that methane emissions from landfills were generally more persistent than those from oil and gas production, with 60% lasting for months or even years.

“When we would go back and scan again later in a few weeks or a few months…or over a few years, we always saw [the methane]Cosworth said.

Landfills are “super emitters,” said Rob Jackson, a professor of environmental sciences at Stanford University, who was not involved in the study.

“Airborne data like this confirm what we've seen on the ground for decades,” he told CNN.

Unfortunately, the landfill problem is unlikely to go away any time soon. “Even in a future where there is no reliance on fossil fuels, humans will likely continue to generate waste,” Cosworth said. “Even if we move to cleaner fuels, we will still be dealing with waste management.”

Scientists say the rapid reduction of methane is one reason The most effective methods To slow climate change due to its strong effect on heating the planet in the short term.

However, most methane policies in the United States Targeting oil and gas industry. “If we want to meet our climate goals, reducing methane emissions cannot come from oil and gas alone,” Cosworth said. “Landfills should get the same kind of attention as oil and gas.”