Greenhouse role of trace gases
Atmospheric scientists are emphasizing the role of trace gases as important factors in a future substantial global increase in temperature. They estimate that, in 1980, trace gases contributed more than half as much to a greenhouse effect as did increased carbon dioxide. From 1880 to 1980, CO/sub 2/ increased from about 275 parts per million (ppm) to 339 ppm. The principal relevant trace gases in 1980 were Ch/sub 4/, 1.6 ppm; N/sub 2/O, 0.3 ppm; CCl/sub 2/F/sub 2/, 0.00028 ppm. CCl/sub 3/F, 0.00018 ppm, and O/sub 3/, which increased in the troposphere substantially over earlier values. Methane (CH/sub 4/) is at present the most effective greenhouse trace gas. Its concentration has been increasing about 1% per year since 1950. The total content in the atmosphere is about 5000 million tons. Methane is destroyed slowly, mainly in the trophosphere, by the reactive OH. Residence time for CH/sub 4/ is 5 to 10 years. This implies an annual addition of at least 500 million tons to hold the level constant. Growth of 1% per year requires an extra addition on the order of 50 million tons. Principal sources of CH/sub 4/ appear to be ruminant animals, organic-rich sediments, and rice paddies. A complicating factor in estimating trends in CH/sub 4/ distribution is the competition of CO for OH. Emissions of CO have been increasing, and they destroy OH that otherwise might react with CH/sub 4/.
- OSTI ID:
- 7120594
- Journal Information:
- Science (Washington, D.C.); (United States), Vol. 231:4743
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CARBON DIOXIDE
ECOLOGICAL CONCENTRATION
FREONS
METHANE
NITROUS OXIDE
OZONE
AIR POLLUTION
GLOBAL ASPECTS
GREENHOUSE EFFECT
POLLUTION SOURCES
TRACE AMOUNTS
ALKANES
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
HALOGENATED ALIPHATIC HYDROCARBONS
HYDROCARBONS
NITROGEN COMPOUNDS
NITROGEN OXIDES
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
POLLUTION
500200* - Environment
Atmospheric- Chemicals Monitoring & Transport- (-1989)