Five consecutive passes of the Tanager-1 satellite since November 2025 have picked up persistent methane clouds above the Chevron-operated Gorgon complex, the most recent in late August showing an average emission rate of about 7.8 tonnes of methane an hour, far exceeding a "super emitter" event under US Environmental Protection Agency guidelines.
The repeated detections prompted the UN to send a warning to Chevron. The UN notes methane is responsible for roughly 25 per cent of global warming and is 80 times more harmful as a greenhouse gas than carbon dioxide.
Chevron confirmed it had received the alert and was working with the UN Environmental Programme (UNEP) to address it. However, a UNEP spokesperson told the ABC it had not received formal feedback from either Chevron or the Australian government, and would update its publicly available data when it had.
"We are engaging with the UNEP, and we are seeking further clarity on their data," a Chevron spokesperson said, adding that satellite monitoring came with "a wide range of uncertainty."
The WA government said it was unclear of its role in managing the potential leak. "The Department of Water and Environmental Regulation is aware of these reports and is investigating them to understand what compliance or regulatory measures may be required," a spokesperson said.
Conservation Council WA executive director Matthew Roberts criticised the lack of action. "What I would hope is that our levels of government are communicating with each other and checking where the responsibility is," he said. "Whatever happens, that is a piece of infrastructure from a private corporation that is profiting off of our resources."
Louis Goddard, head of research at British climate investigative firm Data Desk, said the consistent greenhouse gas levels around the facility were "unusual" and suggested an operational issue. "What we're seeing here is a wasting of gas that they've gone to great lengths to extract in the first place," he said. Data Desk pinpointed the emissions as originating from or near Gorgon's acid gas removal units. Chevron did not respond to specific questions about the cause or whether the emissions had been stopped.
University of Western Australia chemical engineering program chair Bruce Norris said closer measurements were needed, estimating that a few thousand tonnes of methane could have been leaked over a year based on the five satellite observations. Chevron was similarly notified about methane emissions at Gorgon in July 2025. The project has a troubled environmental record, with its carbon capture and storage technology drastically underperforming since operations began in 2016, and an unknown amount of gas seeping into Barrow Island's surface last year.