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Methane is second only to carbon dioxide when it comes to greenhouse trace gases that are being emitted by man and his activities. Methane, even though it has a lower atmospheric concentration than carbon dioxide, contributes significantly to the enhanced greenhouse effect due to its higher global warming potential of 21. This simply means that methane is 21 times more effective at trapping heat than is carbon dioxide.
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Sources |
Emission Processes |
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Landfills – Municipal and Industrial 37% of methane emissions |
Municipal landfills are the single largest manmade source of methane. This is due to decomposition of organic wastes in a low oxygen environment, which produces methane. |
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Natural Gas and Petroleum Systems 20% of methane emissions |
Methane is a major component of natural gas. It is emitted into the atmosphere when leaks in the system occur during operation and maintenance procedures on older equipment. |
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Coal Mining 10% of methane emissions |
During strip mining of coal, methane is released directly into the atmosphere. In underground coal mining, methane is actively ventilated to prevent dangerous concentrations that could explode. Some underground mines have methane-recovery systems. |
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Agriculture – Enteric Fermentation 19 % of methane emissions |
This methane emission is due to animal digestion, especially in cows, buffalo, sheep, and goats. (Ruminants produce more methane) |
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Agriculture – Manure Management 9% of methane emissions |
Decomposition of manure produces methane in low oxygen environments. |
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Agriculture – Rice Cultivation 2% of methane emissions |
In rice paddies, the fields are flooded producing a low oxygen environment. When organic matter decays, methane is released. |
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Agriculture – Residue Burning 0.1% of methane emissions |
The burning of agricultural crop residue produces methane. |
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Other – Wastewater Treatment (0.5%), Industrial Processes (0.2%), Stationary Sources (1%), Mobile Sources (0.8%) 3% of methane emissions |
Methane is released during the treatment of wastewater and during some industrial processes such as the production of petrochemicals and silicon carbide. Stationary and mobile sources produce methane when fossil fuels are combusted. |
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