Methane is a greenhouse gas with high ability to cause warming potential. It has an atmospheric lifetime of about 12 years. It is produced through natural processes (i.e. the decomposition of plant and animal waste), but is also emitted from many man-made sources, including coal mines, natural gas and oil systems, and landfills. Methane directly influences the climate system and also has indirect impacts on human health and ecosystems, in particular, through its role as a precursor to the formation of tropospheric ozone in the lower atmosphere.
Approximately 60% of methane is emitted from human activities. In 2005, agriculture (livestock rearing and rice production), fossil fuel production and distribution, and municipal waste and wastewater management accounted for 93% of global anthropogenic methane emissions. According to the projected trends, without further mitigation efforts, anthropogenic methane emissions are expected to increase by about 25% by 2030 (UNEP & WMO 2011).