18.104.22.168. Sources of Atmospheric Methane
Anaerobic production of methane today occurs both naturally and anthropogenically. Natural sources include natural wetlands (115Mt/a), termites (20Mt/a), and oceans (10Mt/a). Anthropogenic sources include the mining and burning of fossil fuels (100Mt/a), Enteric fermentation in ruminant animals (85Mt/a), rice paddies (60Mt/a), biomass burning (40Mt/a), landfills (40Mt/a) and other wastes (50Mt/a). When all minor sources are included, the total present annual emissions of methane are 535Mt/a (±125Mt).