Example
Leaks from natural gas production release fossil methane into the atmosphere.
The catch
Fossil and non-fossil methane can have different CO₂-equivalent factors because oxidation has different accounting consequences.
Related terms
Methane, Anthropogenic methane, Biogenic methane, Flaring, Fugitive emissions, Global Methane Pledge
In more depth
Fossil methane, explained.
Fossil methane is often the quickest methane to cut, because much of it escapes from equipment that can be fixed. The IEA finds that a large share of oil and gas methane could be avoided with existing technology, often at low cost, through leak detection and repair, replacing leaky equipment and ending routine venting. Coal mines release it too, including mines that closed long ago.
Its age leaves a fingerprint. Fossil methane contains no radiocarbon, because its carbon is far too old, so atmospheric scientists can use isotopes to tell it apart from biogenic methane from cattle or wetlands. Satellites add a second check by spotting large plumes from a single super-emitter, which often accounts for an unusually large share of a region's total.