Methane is the greenhouse gas most responsible for global warming behind carbon dioxide. The largest source of human-caused methane emissions is from oil and gas production, while most of the rest – almost a fifth of global methane emissions – comes from rotting landfills.
For the study, Joannes Maasakkers at the Netherlands Institute for Space Research and a team 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.
Because the satellite has a broad field of view, the team could point two higher-resolution satellites, called GHGSat-C1 and C2, at the cities.
In Buenos Aires, the team found that a large landfill called Norte III accounted for half the city...