August 18, 2022

Satellites have located the world’s methane ‘ultra-emitters’

Satellites have located the world’s methane ‘ultra-emitters’
Satellites have located the world’s methane ‘ultra-emitters’Satellites have located the world’s methane ‘ultra-emitters’

A small number of “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.

Analyses 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.

Plugging 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 Lauvaux of the University of Paris-Saclay and colleagues report in the Feb. 4 Science.

Ultra-emitters 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.

Cleaning up such leaks would be a big first step in reducing overall emissions, says Euan Nisbet, a geochemist at Royal Holloway, University of London in Egham, 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.”

Methane 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).

In oil and gas production, massive methane bursts might be the result of accidents or leaky pipelines or other facilities, Lauvaux 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, Lauvaux 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).

Satellites, such as the European Space Agency’s Tropospheric Monitoring Instrument, or TROPOMI, offer a much bigger window in both space and time. Scientists have previously used TROPOMI 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).

In the new study, the team didn’t include sources in the Permian Basin among the ultra-emitters; the large emissions from that region are the result of numerous tightly clustered but smaller emissions sources. Because TROPOMI doesn’t peer well through clouds, other regions around the globe, such as Canada and the equatorial tropics, also weren’t included.

But that doesn’t mean those regions are off the hook, Lauvaux says. “There’s just no data available.” On the heels of this broad-brush view from TROPOMI, Lauvaux and other scientists are now working to plug those data gaps using other satellites with better resolution and the ability to penetrate clouds.

Stopping all of these big leaks, which amount to an estimated 8 to 12 percent of total annual methane emissions, could save these countries billions of dollars, the researchers say. And the reduction in those emissions would be about as beneficial to the planet as cutting all emissions from Australia since 2005, or removing 20 million vehicles from the roads for a year.

Such a global map can also be helpful to countries in meeting their goals under the Global Methane Pledge launched in November at the United Nations’ annual climate summit, says Daniel Jacob, an atmospheric chemist at Harvard University who was not involved in the study (SN: 1/11/22).

Signatories to the pledge agreed to reduce global emissions of the gas by at least 30 percent relative to 2020 levels by 2030. These new findings, Jacob says, can help achieve that target because it “encourages action rather than despair.”