Nov 10, 2022 - Science

Tracking methane from space could be key to helping slow global warming

Illustration of Earth with map pins with CO2 and Methane molecules as tops pointing at polluted areas

Illustration: Rae Cook/Axios

Satellites orbiting Earth are providing data to precisely point scientists, companies and governments to sources of methane — a strong greenhouse gas.

Why it matters: Cutting methane emissions could help to slow global warming in the next few decades. But efforts to reduce methane hinge on knowing where and how much of the gas is being emitted — and whether companies and governments are responding.

Driving the news: Cutting methane emissions is high on the agenda at this week's UN COP27 climate summit in Sharm el-Sheikh, Egypt.

  • The U.S. and EU are expected to announce an agreement to reduce methane emissions from the fossil fuel sector, Reuters reports. Policies to stop the flaring of gas and to require companies to fix leaks are included in the draft of the pledge.
  • The Climate TRACE coalition released emissions estimates based on satellite imagery and direct gas measurements and found methane leaks and flares during oil and gas production are underreported.
  • The findings haven't been peer-reviewed but suggest methane emissions are much higher — as much as three times — than what countries and companies are reporting.

How it works: Methane makes up about 16% of greenhouse gas emissions but these simple molecules of a single carbon atom bonded to four hydrogen atoms are a fast-acting global-warming gas.

  • Methane traps 80 times more heat in the atmosphere than carbon dioxide.
  • It also lasts a few decades in the atmosphere compared to hundreds of years for carbon dioxide. That's why climate advocates want to focus on reducing emissions of methane now to try to buy time as they attempt to figure out how to remove carbon dioxide from the atmosphere.

Where it stands: More than 100 countries pledged last year to voluntarily reduce emissions of methane by at least 30% of 2020 levels by the year 2030.

  • But emissions are still increasing, according to a report released earlier this year by the methane monitoring company, Kayrros.

Zoom in: Major sources of methane from human activities include oil and gas production, agriculture and waste management. About 18% of global methane emissions come from decaying solid waste in landfills, with China, India and the U.S. as the top emitters in the waste sector.

  • In a recent paper published in Science, researchers used data from the TROPOMI instrument on an ESA satellite and from emissions monitoring company GHGSat to spot methane-emitting sites.
  • They detected and analyzed super-emitting landfills — which released 3 to 29 tons of the gas per hour — in Buenos Aires, Delhi, Lahore, and Mumbai.
  • The team followed up by releasing a global map of more than 100 methane super-emitting landfills — found on every continent but Antarctica — this week at the climate summit.

"Landfills like those in Mumbai, Delhi or Dakar are among the largest point sources of methane globally," says Marcelo Mena, former environment minister of Chile and the CEO of the Global Methane Hub, a philanthropic fund supporting the research.

  • The effect of reducing methane emissions isn't limited to mitigating climate change, he says, adding it reduces the risk of fire, air pollutants and odors that can have health effects on people nearby.
  • Reducing methane emissions is "really tackling the environmental justice issue at the core in the poorest countries," he says.

The big picture: Methane emissions are being detected and tracked by space agencies and companies using a range of instruments on satellites orbiting Earth, as well as low-flying aircraft and thermal imaging. Satellite instruments operate at different frequencies and resolutions, and offer a range of data streams.

  • NASA's Earth Surface Mineral Dust Source Investigation (EMIT) mission onboard the International Space Station (ISS) is now mapping methane-emitting hotspots.
  • About 1,200 parallel imaging spectrometers on EMIT collect 300,000 light absorption patterns of minerals as well as gases in the atmosphere, including methane — per second.
  • The instrument, which measures visible and infrared light and has a resolution down to 60 meters, is "the first of its class," says Robert O. Green, principal investigator of EMIT at NASA's Jet Propulsion Laboratory.

There are open questions about how much point sources of methane vary over time — a key measurement for efforts to mitigate the gas' effects.

  • EMIT's perch on the ISS means it covers broad areas of Earth and, as the space station orbits the planet, the instrument can repeatedly map the same location.
  • Those multiple observations are key to calculating annual emission rates from sources, says Andrew Thorpe, a research technologist at JPL.

What to watch: Several other instruments and satellites that measure methane emissions — including the Carbon Plume Mapper in development at JPL and EDF's MethaneSAT — are expected to launch in 2023.

  • The Global Methane Hub is also developing a system to report methane gas leaks to oil and gas companies — and to the public to hold the producers accountable for any inaction.

Go deeper: Satellites are ushering in a new era of environmental accountability (Axios)

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