composition of the Earth's atmosphere

Substance	Symbol	Concentration *	duration +	rank
Nitrogen	N	780,840		1
Oxygen	O₂	209,480		2
Argon	Ar	9,340		3
Carbon Dioxide	CO₂	383.1 375**	variable to 120 years	4
*Trace elements*
Methane	CH₄	1.7	12 - 18 years	5
Hydrogen	H₂	.55		6
Nitrogen Oxides	NO	.251		7
Nitrous Oxide	N₂O	.31	121 years
Carbon Monoxide	CO	.1
Ozone	O₃	.02
Sulfur Dioxide	SO₂	.0002
trifluoromethyl sulfur pentafluoride	SF₅ CF₃	.00000012***
Other inert gases		24.28

* in parts per million ppm, or ppmv (volume)

+ residency time in the atmosphere, how long a molecule, on average stays active in solution, or in the air.

** c. In 1969, CO•2 measurement was 318 ppm. In 1990 it was 360 ppm. Today it is increasing at more than the 50 year average rate of 1.5 ppm /annum. In 2000-2007, green house gas content of the atmosphere was increasing at 2 ppm in bad years and 1.7 ppm in good years.

*** 7-24-2000 discovered by atmospheric chemists

Carbon dioxide measured @ 383.1 ppm in 2007.

Sources:

Atmospheric Chemistry and Global Change, Brasseur, Orlando, & Tyndall, eds. (New York: Oxford University Press, 1999). p. 9.

Mark Bush, Ecology of a Changing Planet. Upper Saddle River, N. J.: Prentice-Hall, 2000. pp. 361-368.

§§§ Impacts §§§

Page authored by
Dr. J. Siry

September 7, 2005

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