Science & TechClimate
Satellites find Istanbul landfill leaking 7.4 tonnes of methane an hour as COP31 nears
The Seymen dump captures gas to make electricity, yet space data ranks it among the world's biggest landfill emitters, two days before Turkey hosts the climate summit in Antalya.
Key points
- Satellites detected an average 7.4 tonnes of methane an hour at the Seymen landfill west of Istanbul.
- Turkey is the world's fifth-biggest emitter of landfill methane, behind China, the US, Russia and Brazil.
- Turkey's environment ministry says the data are not continuous measurements and cannot give annual emissions.
Satellites have found methane escaping from a landfill west of Istanbul at an average of 7.4 tonnes an hour, even though the site captures gas to generate electricity. The finding comes two days before Turkey opens the COP31 climate summit in Antalya, where it has made methane cuts a priority. The summit runs from November 9 to 20.
The Seymen landfill, in Silivri, takes about 8,500 tonnes of household waste a day, out of roughly 20,000 tonnes produced daily by a city of 16 million. Municipal operator Istac collects the gas, and an energy company burns it at a plant opened in 2020 that makes about 22,000 megawatt-hours a month.
What the satellites saw
Researchers at the University of California, Los Angeles analysed public data from the Tanager-1 satellite run by Carbon Mapper, covering January 2025 to the end of May 2026. They found 70 plumes from Turkey’s 10 highest-emitting waste sites, with average detected rates between 841 kg and 7.4 tonnes an hour. Three of the sites are around Istanbul; others are near Ankara, Izmir and Antalya.
Seymen’s average is just below the top landfill on a 2025 global list. “What stands out is how big its emissions are and how persistently large they are,” said Tia Scarpelli of Carbon Mapper.
The operator and the ministry push back
Turkey’s environment ministry said the data were not continuous measurements and could not be used to work out annual emissions at Seymen. Istac official Aysen Erdincler said readings usually run between 4 and 6 tonnes an hour, and that one day’s reading of 12 tonnes pulled the average up. Istac head Fatih Ugur said about 30 hectares were left uncovered that day while work was done on gas pipes.
Why it matters for COP31
Methane is the biggest cause of warming after carbon dioxide and is over 80 times more potent over its first 20 years in the air. Turkey is the world’s fifth-biggest emitter of methane from solid waste, according to Climate TRACE, behind China, the United States, Russia and Brazil. Its waste methane rose nearly 25% in the decade to 2024, against 6.5% worldwide, according to World Bank data.
Turkey is not among the countries that signed the Global Methane Pledge, launched at COP26 in 2021 to cut methane by 30% by 2030. Selim Yildirim of the Ankara policy group D84 said it could still join at COP31, but that rules forcing operators to capture and reuse gas would matter more. Scarpelli said repairs to cracked covers and faulty gas wells at the biggest dumps could bring outsized gains.