After carbon dioxide (CO2), methane, CH4 is the largest greenhouse gas. Greenhouse gases contribute to global warming thanks to their ability to absorb and emit radiant energy. There are both natural and human-made sources of methane ranging from wetlands to landfill emissions to flatulence. About 550 million metric tons of methane per year are emitted into the Earth’s atmosphere. While the gas is short-lived, methane’s large contributing influence on trap heat in the Earth’s atmosphere makes mitigation a priority. With half of the methane emissions originating from human activities, researchers from NASA wanted to map out point-source emitters in California to understand where the highest volume of methane emissions occur.
To do this, researchers engaged in five campaigns over a three-year period that surveyed 272,000 infrastructure elements using an airborne imaging spectrometer (the Airborne Visible InfraRed Imaging Spectrometer – Next Generation (AVIRIS-NG) to map methane plumes. The research project covered oil and gas, manure-management and waste-management sectors within the state of California. With a spatial resolution of ten meters, the researchers mapped out 550 individual point sources emitting plumes of highly concentrated methane. Furthermore, ten percent of those sources are responsible for producing 30 percent of methane emissions in California.
The results of the detailed survey will be use to strategize mitigative responses. For example, of the 270 landfills surveyed, 30 were responsible for 40% of the total point-source emissions from the survey. These landfills may have leaks or failures with their gas-capture systems that could be addressed.
The results of the study are available as an interactive map via NASA’s Methane Source Finder.
Duren, R. M., Thorpe, A. K., Foster, K. T., Rafiq, T., Hopkins, F. M., Yadav, V., … Miller, C. E. (2019). California’s methane super-emitters. Nature, 575(7781), 180–184. https://doi.org/10.1038/s41586-019-1720-3
Interactive map: NASA’s Methane Source Finder