A methane molecule consists of one atom of carbon linked to four atoms of hydrogen. It has a Global Warming Potential of 21 over 100 years.
Methane is produced by a number of industrial processes such as the production and transport of coal, natural gas and oil. Methane is also produced by a number of natural process such as the degradation of organic wastes in landfills and by livestock. Methane is also deliberately produced by the industrial process of anaerobic digestion where it is contained to prevent it entering the atmosphere and burned in a gas engine to produce electricity.
Globally, 60% of methane production comes from human activities. Methane does not spend as much time in the atmosphere as carbon dioxide but is c. 21 times more efficient at trapping radiation over a 100 year period.
In 2016, methane represented 10% of all greenhouse gases produced in the USA that year by human activities.
A breakdown of methane emissions in the USA for 2016 revealed the following sources:
Energy and industry
The largest sources of methane occur during the production of natural gas and petroleum. Methane is the primary component of natural gas.
Domesticated animals such as cattle, sheep and goats generate methane through their digestive processes. Methane can also be produced if livestock manure is stored in lagoons or tanks where it can become anaerobic. These two activities – livestock rearing and manure processing – are together the largest overall source of methane in the USA.
Waste from homes and business
The decomposition of organic wastes in landfills represents the third largest source of methane.
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