Dedicated satellites detect 92-100% of methane plumes on clear days

Stanford researchers ran a yearlong blind test in the Arizona desert, timing 481 controlled methane releases of known flow to overpasses by 11 government, nonprofit and commercial satellites. Fifteen teams across nine countries independently judged whether a plume was present and estimated emissions. On clear days, dedicated methane sensors detected 92-100% of test plumes; repurposed instruments found 62-88%, while general-purpose land scanners found only 29-37%. Most quantity estimates were within roughly plus or minus 50% of actual flows, with over- and underestimates balancing on average well enough to prioritize major leaks. The study also included 265 zero-release overpasses: 79% of false positives came from AI methods applied to general land-scanning data. Clouds, wind, water and non-desert surfaces can weaken performance, and a controlled trial is not everyday global operation.