Methane is a colorless, odorless gas that is the main component of natural gas. In the atmosphere it acts as a potent greenhouse gas, trapping heat far more effectively than carbon dioxide on a per-molecule basis over a 20-year period.

Natural sources include wetlands, termites, and geological seeps. Human sources include livestock digestion, rice cultivation, landfills, and leaks from oil and gas systems. Concentrations have more than doubled since pre-industrial times.

Methane has a relatively short atmospheric lifetime of about a decade, so reducing emissions can produce relatively quick benefits for the climate. Detection of methane plumes from space has improved, helping identify large emission sources. The gas also contributes to the formation of ground-level ozone.

Efforts to cut methane emissions are now a significant part of climate strategies worldwide.