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Artist's illustration of the GHGSat spacecraft measuring methane in orbit. | Photo: GHGSat
When it comes to greenhouse gas emissions, carbon dioxide receives the lion's share of attention worldwide.
However, methane is the second largest source of anthropogenic emissions. global warming. High share methane emissions comes from the energy sector, often from concentrated “point sources” such as flare stacks, coal mines and open pit mines. To help reduce these emissions, we must first identify the main culprits – and new ones satellite Data helps us do just that.
Using high-resolution observations from the GHGSat satellite constellation, the researchers created a global, site-level picture of methane emissions, identifying thousands of individual oil, gas and coal sites that emit methane. greenhouse gas V Earth's atmosphere.
“This is the first global gridded estimate of annual methane emissions derived from site-scale measurements. This is an advance in measurement-based accounting that is driven by the extensive scale of the GHGSat satellite constellation to measure methane around the world,” said Dylan Jervis of GHGSat Inc., lead author of the study. new research The study results were published December 11 in the journal Science.
“This information will be useful in improving the understanding and forecasting of methane emissions and therefore provide information useful for guiding mitigation efforts,” Jervis told Space.com.
Traditionally, scientists have measured methane emissions using bottom-up inventories, which estimate emissions based on industry activity but can miss short-term fluctuations such as leaks, and top-down atmospheric measurements, which directly measure methane concentrations but lack the resolution to pinpoint specific sources. None of them can provide a very accurate picture of global methane emissions from the energy sector. But Constellation GHGSatoperated by the Canadian company GHGSat, bridges this gap by combining meter-scale spatial resolution with global coverage.
By analyzing GHGSat observations of methane plumes collected in 2023, the team estimated annual methane emissions from 3,114 oil, gas and coal facilities around the world to be about 9 million tons (8.3 million metric tons) per year.
Example of GHGSat methane plumes detected in a coal hole, oil and gas flare stack, and coal mine. | Photo: GHGSat
Geographically, the largest emission sources are clearly visible in satellite data. “The countries where we measure the largest emissions of methane from oil and gas are Turkmenistan, the United States, Russia, Mexico and Kazakhstan,” Jervis said. “The countries where we measure large coal emissions are China and Russia.”
While bottom-up inventories are reasonably good at estimating methane emissions at scales as large as countries, they are not as accurate when scaled up. “We found moderate agreement between emissions estimates measured by GHGSat and bottom-up inventory projections at the country level, but very little agreement at 0.2 x 0.2 degrees. [about 20 by 20 kilometers] spatial resolution,” Jervis said. Thus, effective change may need to occur at the institutional level rather than at the country level.
The researchers tracked how often individual sites emitted noticeable plumes of methane, a measure they called persistence.
“Conserving emissions is more a matter of sector than of region,” Jervis said. At coal plants, methane plumes were detected on average in about half the cases. Oil and gas targets, in contrast, were much more variable, emitting detectable methane on average in only about 16% of satellite observations. This variability makes it particularly difficult to capture oil and gas emissions when monitoring is infrequent.
To obtain the most accurate and actionable methane estimates, detailed studies like those provided by GHGSat are critical—which is why GHGSat is expanding its constellation. Two new satellites were launched in June and two more in November, bringing the company's total number of satellites to 14. “This will provide better coverage, both spatially and temporally, allowing us to detect more emissions and monitor them more frequently,” Jervis said.
