Around of a fifth of global methane emissions come from rotting landfills. Satellites have now spotted some particularly large emitters
A single landfill can be responsible for as much as half of a city’s methane emissions. But covering them up along with other measures could drastically reduce how much gas gets released into the atmosphere.
Behind carbon dioxide, methane is the greenhouse gas most responsible for global warming. The largest source of human-caused methane emissions is from oil and gas production, followed closely by bovine flatulence. Most of the rest – almost a fifth of global methane emissions – comes from rotting landfills.
Joannes Maasakkers at the Netherlands Institute for Space Research and colleagues used satellites to identify the landfills behind much of the methane emissions in four cities: Buenos Aires in Argentina, Lahore in Pakistan, and Mumbai and Delhi in India.
The researchers identified the cities as methane hotspots using an instrument on board the Copernicus Sentinel-5P satellite that monitors methane emissions across the planet each day. However, the satellite has a broad field of view, so the team then pointed two higher-resolution satellites called GHGSat-C1 and C2 at the cities.
In Buenos Aires, the researchers found that a large landfill called Norte III accounted for half the city’s methane emissions. Almost 90 per cent of the methane came from an uncovered part of the landfill. A landfill in Mumbai accounted for 26 per cent of the city’s methane emissions. The largest landfill sources in Lahore and Delhi were responsible for 12 and 6 per cent of methane emissions respectively.
“The emissions from individual facilities are very significant,” says Maasakkers. They also point to obvious places to focus emission-reduction efforts. Covering landfills and collecting methane, and other steps like reducing the amount of organic waste could reduce methane emissions from landfills by sixfold, says Maasakkers.
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