Satellite data shows landfills are methane ‘super-emitters’

BENGALURU, India (AP) – Landfills release far more planet-warming methane into the atmosphere from decomposing waste than previously thought, a study suggests.

Researchers used satellite data from four major cities around the world – Delhi and Mumbai in India, Lahore in Pakistan and Buenos Aires in Argentina – and found that emissions from landfills in 2018 and 2019 were 1.4 to 2.6 times higher than previous estimates.

The study, published in Science Advances on Wednesday, is aimed at helping local governments carry out targeted efforts to limit global warming by pinpointing specific locations of major concern.

When organic waste such as food, wood or paper breaks down, it emits methane into the air. Landfills are the third largest source of methane emissions globally, after oil and gas systems and agriculture.

Although methane accounts for only about 11% of greenhouse gas emissions and lasts about a dozen years in the air, it traps 80 times more heat in the atmosphere than carbon dioxide does. Scientists estimate that at least 25% of today’s warming is driven by methane from human actions.

“This is the first time that high-resolution satellite images have been used to observe landfills and calculate their methane emissions,” said Joannes Maasakkers, lead author of the study and atmospheric scientist at the Netherlands Institute for Space Research.

“We found that these landfills, which are relatively small compared to city sizes, are responsible for a large portion of the total emissions from a given area,” he said.

Satellite data to detect emissions is still a relatively new field, but it is being used more and more to observe gases around the world. This means that several independent organizations track greenhouse gases and identify large emissions, whereas previously local authorities were the only available source.

“This new work shows how important it is to manage landfills better, especially in countries like India where landfills often burn and release a wide range of harmful pollutants,” said Euan Nesbit, a soil scientist at Royal Holloway, University of London, who did not was part of the study.

Earlier this year, smoke hung over New Delhi for days after a massive landfill caught fire as the country sweltered in an extreme heatwave with temperatures exceeding 50 degrees Celsius (122 Fahrenheit). At least two other landfill fires have been reported in India this year.

Nesbit added that the new satellite technology, combined with measurements on the ground, makes it easier for scientists to identify “who is polluting the world”.

China, India and Russia are the world’s biggest methane polluters, according to a recent analysis from the International Energy Agency.

At last year’s UN climate conference, 104 countries signed a pledge to reduce methane emissions by 30% by 2030 compared to 2020 levels. Both India and China have not signed.

The authors plan to conduct more research on landfills worldwide in future studies.

“It’s a rapidly developing field, and we expect more interesting data to come out soon,” Maasakkers said.

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Follow Sibi Arasu on Twitter at @sibi123

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