Any process that results in the production of methane and its release into the atmosphere can be considered a "source". The known sources of methane are predominantly located near the Earth's surface. Two main processes that are responsible for methane production include microorganisms anaerobically converting organic compounds into methane (methanogenesis), which are widespread in aquatic ecosystems, and ruminant animals. Other natural sources include melting permafrost, wetlands, plants, and methane clathrates.