Methane

CH₄ emissions

Stern and Kaufmann (1995) present estimates for global anthropogenic and natural methane emissions from 1860 - 1991. They distinguish the following source categories: gas flaring, gas supply, coal mining, biomass burning, animals, rice, and landfills. They compared their results to the Khalil and Rasmussen (1994) deconvolution estimates. The trends show an increasing anthropogenic emission of methane, although the increase has slowed down in recent years (slower population growth resulted in a retarding increase in rice and livestock emissions, an increase in energy prices reduced gas flaring levels, fuel substitution away from coal, reduction of tropical deforestation in the late 1980s in South and Central America). Etherdige et al. (1998) published long time series of methane concentrations from 1000 A.D. to present times, based on ice cores measurements. According to their research, the industrial period is marked by high methane growth rates from 1945 to 1990, peaking at about 17 ppb per year in 1981, and decreasing significantly since. They calculated an average total methane source of 250 Tg per year for 1000-1800 A.D.. reaching near stabilization at about 560 Tg per year in the 1980s and 1990s. 

Download table: Global CH4 estimates (xls, 74Kb).

Major methane sources in 1990 were enteric fermentation (29%), rice cultivation (19%), landfills (11%) and coal production (12%). the top 5 regions of methane emissions were at that time the South Asia (16%), East Asia (15%), former USSR (15%), USA (13%) and Latin America (10%). 

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