Researchers have conducted the largest ever controlled test of space-based methane monitoring, finding that dedicated methane sensors correctly detected nearly all methane plumes released on clear days.
Published October 14 in Nature , the results provide a benchmark for satellite systems increasingly used by regulators, environmental groups, and companies to detect leaks and identify super-emitters of the planet-warming gas.
"There has been significant skepticism over the years about whether methane tracking really works because it's a challenging technical problem to detect the gas from space," said senior study author Adam Brandt , a professor of energy science and engineering in the Stanford Doerr School of Sustainability . "Our results should give regulators, policymakers, producers of methane, and the general public a lot of confidence moving forward."
Testing satellite observations and algorithms
Together with PhD student and lead author Frances Reuland , Brandt and collaborators timed 481 methane releases at a Stanford research site in Casa Grande, Arizona, to overpasses by 11 government, nonprofit, and commercial satellites throughout 2025.
Fifteen research teams from corporations, nonprofits, government agencies, and academia across nine countries independently analyzed the observations, assessing whether each satellite image showed a methane plume and, if so, how much methane was released.
The study authors compared the resulting estimates with the known releases. Instruments designed specifically for methane monitoring produced the best detection rates, correctly identifying the presence of 92-100% of test plumes.
Most estimates based on these observations were up to 50% higher or lower than actual emission amounts, but the over- and underestimates roughly balanced out on average. That makes the estimates reliable enough to flag large leaks for follow-up, inform governments' regional greenhouse gas emissions inventories, and assess the relative emissions intensity of different oil and gas regions, the authors said.
"In many cases, the detection is the important part," said Brandt. "As long as you know approximately how big it is, then you still know you need to go fix it."
Under ideal conditions, with few clouds and moderate wind, these instruments reliably detected plumes when methane flowed at rates down to about 50-200 kilograms per hour, depending on the system. This emission rate is close to the threshold of 100 kilograms per hour that triggers reviews under some state and national "super-emitter" programs.
"These results were great to see, and we hope they build confidence in this field overall," said Reuland, who is a member of Brandt's lab and a PhD student in energy science and engineering in the Doerr School of Sustainability.
Satellite-based monitoring systems detect methane using infrared light reflected off Earth's surface. That reliance on reflected sunlight means even the dedicated instruments aboard GHGSat and Tanager-1 satellites struggled to detect methane plumes through clouds.
"This poses problems in some key methane-emitting regions," the authors write, "including tropical oil and gas producers Nigeria and Venezuela, as well as cold, cloudy climates like Canada and Russia." More research is needed, they added, to understand how these satellite systems and algorithms work over non-desert terrains, across various weather conditions, and over open water.
Opportunity to improve AI-powered methane monitoring
When skies over the Casa Grande test site were clear, instruments repurposed for methane sensing, such as Germany's Environmental Monitoring and Analysis Program, or EnMAP, detected 62-88% of methane plumes. General-purpose land-scanning systems aboard U.S. and European government satellites detected just 29-37% and proved especially error prone for releases below 1,000 kilograms per hour.
The land-scanning systems gather less of the spectral data required to isolate methane's unique signature. Their extensive coverage and historical archives remain valuable, however, for documenting long-term trends and identifying large leaks, the researchers said.
The authors gave analytics teams observations from 265 overpasses when no methane was released to test for false positives, which can reduce public trust in results and waste resources on efforts to address non-existent leaks.
These proved relatively rare with most methods, except when teams analyzed data with emerging artificial intelligence approaches. According to the study, 79% of false positives originated from commercial teams applying AI-powered methods to data from land-scanning government satellites.
The researchers said the AI methods tested need improvement, and that the new data from the Casa Grande experiments could help refine them. "With this study, we have orders of magnitude more controlled-source data points than we've ever had before for testing methane detection from space," said Reuland.
Approximating real-world emitters
At the research site, researchers piped compressed natural gas, which is mostly methane, through a release stack, setting the emission rates to approximate point sources such as landfills and oil and gas facilities.
Controlled through an online interface, the releases lasted 8 to 10 minutes and ranged from about 10 to 1,200 kilograms of methane per hour. Over the full year of the experiment, the team released less than 50 metric tons of methane, equivalent to the annual emissions from a herd of about 500 dairy cows or about 13 seconds of methane emissions from global fossil fuel energy operations.
"By establishing these findings," Reuland and co-authors write, "we hope this moves the conversation beyond if these systems work, toward discussions of how, given algorithmic trade-offs, and where they can be most effectively applied to drive global methane mitigation."
'Multiple motivations' for fixing methane leaks
Rapidly reducing the world's methane emissions, the biggest driver of climate change after carbon dioxide, is a major focus of international efforts to slow global temperature increases. Carbon dioxide lasts longer, but methane is 80 times more potent at trapping heat during its first 20 years in Earth's atmosphere, giving it an outsized impact on near-term temperatures.
If monitoring and detection of leaks and intentional venting lead to repairs and overall emission reductions, this can deliver multiple benefits in addition to mitigating climate change. Some relatively low-cost repairs to oil and gas infrastructure, one of the largest sources of human-caused methane emissions , can yield financial gains for operators by keeping saleable gas from escaping, the authors said.
"Plus, there are safety issues associated with releasing methane because it is flammable and it contributes to ground-level ozone, a health hazard," said Brandt. "There are multiple motivations here for supporting satellite monitoring where it's win-win-win for the environment, the producers, and the general public."
Co-authors of the study are affiliated with the University of Michigan, Ann Arbor; University of California, Berkeley; University of Iowa; and the Max Planck Institute for Chemistry.
Brandt is also a senior fellow at the Precourt Institute for Energy, part of the Doerr School of Sustainability. He is a member of Carbon Mapper's Science and Measurement Committee, which co-author Eric Kort chairs.
Analysis teams included Carbon Mapper; the International Methane Emissions Observatory (IMEO); NASA JPL; and Space Research Organization Netherlands (SRON); Universitat Politècnica de València; Nanjing University; University of Bremen, Germany; GHGSat; Google; Kayrros; Orbio Earth; Arka; Orbital Sidekick; Geolabe; and Momentick.
Funding was provided by the Global Methane Hub, the Grantham Foundation, Saudi Aramco, and the Stanford Knight-Hennessy Scholars program, where Reuland was a scholar in the 2023 cohort.
This work was also supported by the Natural Gas Initiative, part of the Center for Fuels of the Future industrial affiliates program. Stanford industrial affiliates programs are funded by membership fees from companies. View current Stanford Doerr School of Sustainability affiliates members .
