“ultra-emitters” of methane from oil and gas production contribute as much as 12 percent of emissions of the greenhouse gas to the atmosphere every year — and now scientists know where many of these sources are of satellite images from 2019 and 2020 reveal that a majority of the 1,800 biggest methane sources come from six major oil- and gas-producing countries: Turkmenistan led the pack, followed by Russia, the United States, Iran, Kazakhstan and Algeria.

 those leaks would not only be a boon to the planet, but also could save those countries billions in U.S. dollars, climate scientist Thomas  of the University of and colleagues report in the Feb. 4 Science.

 are sources that spurt at least 25 metric tons of methane per hour into the atmosphere. These occasional massive bursts make up only a fraction — but a sizable one — of the methane shunted into Earth’s atmosphere annually.

up such leaks would be a big first step in reducing overall emissions, says , a geochemist at Royal Holloway, University of London in , who was not involved in the study. “If you see somebody badly injured in a road accident, you bandage up the bits that are bleeding hardest.”

has about 80 times the atmosphere-warming potential of carbon dioxide, though it tends to have a much shorter lifetime in the atmosphere — 10 to 20 years or so, compared with hundreds of years. The greenhouse gas can seep into the atmosphere from both natural and human-made sources (SN: 2/19/20).

 oil and gas production, massive methane bursts might be the result of accidents or leaky pipelines or other facilities,  says. But these leaks are often the result of routine maintenance practices, the team found. Rather than shut down for days to clear gas from pipelines, for example, managers might open valves on both ends of the line, releasing and burning off the gas quickly. That sort of practice stood out starkly in satellite images as “two giant plumes” along a pipeline track,  says.

Stopping such practices and repairing leaky facilities are relatively easy, which is why such changes may be the low-hanging fruit when it comes to addressing greenhouse gas emissions. But identifying the particular sources of those huge methane emissions has been the challenge. Airborne studies can help pinpoint some large sources, such as landfills, dairy farms and oil and gas producers, but such flights are limited by being both regional and of short duration (SN: 11/14/19).

such as the European Space Agency’s Tropospheric Monitoring Instrument, or , offer a much bigger window in both space and time. Scientists have previously used to estimate the overall leakiness of oil and gas production in Texas’s massive Permian Basin, finding that the region sends twice as much methane to the atmosphere as previously thought (SN: 4/22/20).