- Methane (CH4) is a significant greenhouse gas produced through both natural and anthropogenic processes, often involving anaerobic decomposition. - 1. Biomass burning: Incomplete combustion during forest fires, grassland fires, and agricultural burning releases methane. - 2. Wastewater treatment: Organic matter in wastewater decomposes anaerobically in treatment plants, producing biogas, which contains methane. - 3. Coal mining: Methane is often trapped within coal seams during their formation and is released into the atmosphere during mining operations. This is known as coal seam methane or coal mine methane. - 4. Permafrost: Permanently frozen ground (permafrost) contains vast amounts of trapped organic matter. As permafrost thaws due to warming temperatures, this organic matter decomposes anaerobically, releasing significant amounts of methane.