The world’s worst mega-leaks of the potent greenhouse gas methane in 2025 have been revealed by an analysis of satellite data.
The super-polluting plumes from oil and gas facilities have a colossal heating impact on the climate but often result from poor maintenance and can be simple to fix. The assessment found dozens of mega-leaks, each having the same global heating impact as a coal-fired power station.
The researchers said it was “maddening” that such easy action to fight the climate crisis was not being taken, and said people should be angry. Stopping the leaks can even be free, given that captured gas can be sold – methane is the “natural gas” that fires power stations.
The mega-leaks occur across the world, but the top 25 list, produced by the Stop Methane Project at the University of California, Los Angeles (UCLA), is dominated by facilities in Turkmenistan. The scale of methane leaks in the secretive and authoritarian state has previously been described as “mind-boggling”.
Super-polluting plumes were also seen in the US, the largest detected in 2025 occurring in Texas and leaking 5.5 tonnes of methane per hour, equivalent to running about a million fuel-guzzling SUVs. Venezuela (five) and Iran (three) also had multiple mega-leaks from state-owned facilities.
The Stop Methane Project also analysed super-polluting plumes from landfill sites, where rotting organic waste can release huge volumes of methane when not well managed. The worst sites ranged across the world, from Turkey to Algeria and Malaysia to the US.
Methane emissions cause 25% of global heating today, and there has been a “scary” surge since 2007, according to scientists. They have warned that this acceleration seriously risks triggering catastrophic climate tipping points. However, cutting methane emissions has a rapid impact, because the gas is naturally removed from the atmosphere far quicker than carbon dioxide. Some experts call cutting methane the climate “emergency brake”.
“It is really maddening,” said Cara Horowitz at UCLA. “These sites are the result of poor maintenance – if you upgraded the infrastructure a little bit, did good housekeeping, you could solve a really important part of the problem.
“We’re hoping that by bringing visibility to these major issues, we will help increase public and political pressure to do something.”
Unlike previous lists of plumes, the UCLA project investigated the probable operators of the mega-leak sites.
The super-polluting plume in Texas appears to be operated by Energy Transfer. The company did not reply to a request for comment.
“Methane was the stealth pollutant gas for many years: invisible, out of sight and out of mind,” said Horowitz. “But we can now see these tremendously powerful emissions using satellites and use that as a wake-up call for the world.”
The UCLA Stop Methane analysis is based on data from Carbon Mapper and found 4,400 significant plumes in 2025, each emitting more than about 100kg/hour, equivalent to running 20,000 SUVs. In the US, nine of the 10 worst leaks were in Texas.
“Americans should be surprised and angered by the fact that the US lands pretty high on this list of top super-polluting plumes,” said Horowitz. “We in the US tend to think of our industry as fairly well and cleanly run, but this shows that we still have work to do.”
Turkmen officials claimed in October that methane mega-leaks had been reduced. “Management has placed this under special control, and leaks are being repaired locally within two to three days,” said Muhammetberdi Byashiev, the head of the environmental protection department at the state company Türkmengaz, citing collaboration with the UN, International Energy Agency and EU. However, the new analysis shows substantial mega-leaks remain.
“It’s clear that Turkmenistan is trying to access the European market,” said Horowitz. “European potential buyers should pay attention to our results and think of this as a ‘buyer beware’ moment.” The EU is phasing in strict limits on methane leaks linked to imported gas.
Mary Nichols, the former chair of the California Air Resources Board and a member of Carbon Mapper’s policy and impact committee, said: “Methane is a more powerful climate villain than any other air pollutant because it acts quickly and is emitted in large volumes. It is also relatively cheap and easy to control. New, detailed satellite pictures can help target the countries and companies that need to be held accountable.”
The Guardian contacted Türkmennebit, Türkmengaz, Petróleos de Venezuela SA, the National Iranian Oil Company and the National Iranian Gas Company but did not receive replies.
Methodology note: Carbon Mapper uses data from two satellites to measure the plumes as they pass overhead. Leak rates from a plume on different days are averaged and days with no leaks are taken into account. The satellites cannot collect data at night or through heavy clouds, so not every plume may be detected. The Stop Methane Project only considered plumes that were detected at least twice. The top 25 oil and gas plumes were each detected an average of seven times and the top 25 landfill plumes were each detected an average of 11 times.
