Sources of Methane Emissions

from the EPA:

Human-related Sources

In the United States, the largest methane emissions come from the decomposition of wastes in landfills, ruminant digestion and manure management associated with domestic livestock, natural gas and oil systems, and coal mining. Table 1 shows the level of emissions from individual sources for the years 1990 and 1999 to 2003.

Table 1 U.S. Methane Emissions by Source (TgCO₂ Equivalents)

Source Category	1990	1999	2000	2001	2002	2003
Landfills	172.2	134.0	130.7	126.2	126.8	131.2
Natural Gas Systems	128.3	127.4	132.1	131.8	130.6	125.9
Enteric Fermentation	117.9	116.8	115.6	114.5	114.6	115.0
Coal Mining	81.9	58.9	56.2	55.6	52.4	53.8
Manure Management	31.2	38.8	38.1	38.9	39.3	39.1
Wastewater Treatment	24.8	33.6	34.3	34.7	35.8	36.8
Petroleum Systems	20.0	17.8	17.6	17.4	17.1	17.1
Rice Cultivation	7.1	8.3	7.5	7.6	6.8	6.9
Stationary Sources	7.8	7.1	7.3	6.7	6.4	6.7
Abandoned Coal Mines	6.1	7.3	7.7	6.9	6.4	6.4
Mobile Sources	4.8	3.6	3.4	3.1	2.9	2.7
Petrochemical Production	1.2	1.7	1.7	1.4	1.5	1.5
Iron and Steel	1.3	1.2	1.2	1.1	1.0	1.0
Agricultural Residue Burning	0.7	0.8	0.8	0.8	0.7	0.8
Total for U.S.	605.3	557.3	554.2	546.7	542.3	544.9