Landfilling, the most common waste management practice, results in the release
of methane from the anaerobic decomposition of organic materials. Methane is 21
times more potent a GHG than carbon dioxide. However, landfill methane is also a
source of energy, and some landfills capture and use it for energy. In addition,
many materials in landfills do not decompose fully, and the carbon that remains
is sequestered in the landfill and not released into the atmosphere.