Two or three nights a week, a foul odour settles over the villages outside Istanbul, and windows stay shut even on the hottest summer nights. Residents of Yolçatı and nearby settlements have lived with this for years, and they have always known where it comes from: the Silivri municipal waste dump, a few miles away, where rotting food and organic waste release a constant stream of noxious gas. "The smell is not subtle. It suffocates you," said Kemalettin Özenç, a resident who often sits outside the local tea shop until midnight, waiting for the air to clear enough to go inside.

What looks like a local nuisance turns out to be a problem with global consequences. Among the gases escaping from Silivri is methane, a greenhouse gas many times more potent than carbon dioxide in the short term, and the site is leaking so much of it that the plume can be seen by satellites orbiting the Earth. Researchers at the University of California, Los Angeles, who track such emissions worldwide, found that Silivri releases an average of 7.4 tonnes of methane every hour, making it one of the most severe "super-emitting" landfills identified anywhere on the planet.

Its climate impact, they calculate, is roughly equivalent to 1.5 million SUVs left idling continuously. Silivri is not alone. Similar super-emitting dumps have been traced from İzmir in the west to Ankara and Antalya further south, forming a pattern the UCLA team described as "mind bogglingly large.

" The timing is awkward for Turkey, which will host the Cop31 UN climate summit in November and has pushed methane reduction as a central item on its agenda, with first lady Emine Erdoğan campaigning internationally on waste reform. For Özenç and his neighbours, the gap between international pledges and the smell outside their windows remains difficult to ignore.