Major Greenhouse Gases
Greenhouse Gas
Sources
Lifespan in
Atmosphere
Carbon dioxide
(CO2)
Natural: Respiration, decomposition
Anthropogenic: burning fossil fuels,
deforestation, cement production
Natural: anaerobic decomposition
Anthropogenic: leaking natural gas from
drilling sites, pipelines and storage
facilities, cattle, rice paddies, landfills
Natural: bacteria in soils and the ocean
Anthropogenic: fertilizer use, livestock
waste, fossil fuel combustion, sewage,
industrial processes (especially the
production of nylon)
Fossil fuel combustion
Methane (CH4)
Nitrous Oxide (N2O)
Ozone (O3) in the
troposphere
Chlorofluorocarbons Refrigerators, air conditioners,
(CFCs)
manufacturing foam products, aerosols,
etc. No natural sources.
Sulfur Hexafluoride Used in circuit breakers. No natural
sources.
GWP (Global
Warming Potential)
100 years
% of Anthropogenic
Warming Resulting
From this Gas
70%
12 years
25%2
28 - 36
114 years
6%
298
Hours to days
8%
*
varies
Effect will decrease
over time as CFCs are
phased out
Varies but generally
well over 1000
3,200 years
1
22,800
GWP is a comparison of the global warming potential of one unit of the gas compared to one unit of carbon dioxide. The higher
the GWP, the more effectively it traps heat. *The short lifespan of ozone makes it difficult to calculate a meaningful GWP for this
gas.
The magnitude of the role a gas plays in climate change includes the concentration in the atmosphere and the amount of the gas
released each year, its lifespan in the atmosphere (the length of time the average molecule spends in the atmosphere), and its
GWP. Carbon dioxide is generally considered to be the most important greenhouse gas because we release so much carbon
dioxide into the air each year.