How Much are Greenhouse Gas Concentrations Changing?
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  1. Is there a seasonal variation? Is the concentration higher in summer or in winter? What biological processes might account for the seasonal differences?
  2. Is the northern hemisphere concentration the same as the southern hemisphere? Do gases with longer atmospheric lifetimes have smaller hemispheric differences?
  3. What is the concentration and how quickly is it changing?
  4. How does the concentration change during your lifetime compare with the seasonal variation?
  5. What would you predict for the concentration in 2100?
  6. Which gases should we worry about most?
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Concentration Units*
(Click to see graph)
Global Warming Potential (100-year)**
Atmospheric lifetime (years)**
Carbon dioxide
CO2
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ppm
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long term
1
100
Methane
CH4
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ppb
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long term
28.5
12.4
Nitrous oxide
N2O
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ppb
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long term
264.8
121
Ozone
O3
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ppb
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Total column (Dobson)
hours-days
Hydrogen
H2
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ppb
1-2
Carbon monoxide
CO
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ppb
1.9
0.25
Trichlorofluoromethane
CCl3F
CFC-11
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ppt
4,660
45.0
Dichlorodifluoromethane
CCl2F2
CFC-12
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ppt
10,200
100.0
Trichlorotrifluoroethane
CCl2FCClF2
CFC-113
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ppt
5,820
85.0
Carbon tetrachloride
CCl4
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ppt
1,730
26.0
Chloroform
CHCl3
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ppt
16
0.40
Dichloromethane
CH2Cl2
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ppt
9
0.4
Difluoromethane
CH2F2
HFC-32
Component (50%) of R-410A
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ppt
677
5.2
Methyl chloride
CH3Cl
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ppt
12
1.0
Tetrachloroethene
Cl2C=CCl2
Perchloroethylene (perc)
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ppt
0.25
Methyl chloroform
CH3CCl3
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ppt
160
5.0
Chlorodifluoromethane
CHClF2
HCFC-22
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ppt
1,760
11.9
Chlorodifluoroethane
CH3CClF2
HCFC-142b
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ppt
1,980
17.2
Dichlorofluoroethane
CH3CFCl2
HCFC-141b
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ppt
782
9.2
Difluoroethane
CH3CHF2
HFC-152a
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ppt
138
1.5
Tetrafluoroethane
CH2FCF3
HFC-134a
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ppt
1,300
13.4
1,1,1-Trifluoroethane
CH3CF3
HFC-143a
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ppt
4,800
47.1
Pentafluoroethane
CHF2CF3
HFC-125
Component (50%) of R-410A
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ppt
3,170
28.2
2,3,3,3-Tetrafluoropropene
CF3CF=CH2
HFO-1234yf
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4
0.029
1,1,1,3,3-Pentafluorobutane
CF3CH2CF2CH3
HFC-365mfc
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ppt
804
8.7
Fluoroform
CHF3
HFC-23
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ppt
12,400
222
Perfluoroethane
CF3CF3
PFC-116
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ppt
11,100
10,000
Bromochlorodifluoromethane
CBrClF2
Halon-1211
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ppt
1,750
16
Methylbromide
CH3Br
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ppt
2
0.8
Dibromotetrafluoroethane
CBrF2CBrF2
Halon-2402
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ppt
1,470
20
Bromotrifluoromethane
CBrF3
Halon-1301
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ppt
6,290
65
Sulfur hexafluoride
SF6
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ppt
23,500
3,200
Trifluoromethyl sulfur pentafluoride
CF3SF5
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ppt
17,400
800
Nitrogen trifluoride
NF3
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ppt
16,100
500
Carbon tetrafluoride
CF4
PFC-14
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ppt
6,630
50,000
ppm = parts per million (106), ppb = parts per billion (109), ppt = parts per trillion (1012).

Infrared spectral links are to the NIST Chemistry WebBook (%T, peaks down) or the Gasmet IR Spectrum Collection (A, peaks up).

*Concentration data from the Scripps CO2 Program, the Carbon Dioxide Information Analysis Center (U. S. Department of Energy), Global Greenhouse Gas Reference Network (U. S. National Oceanic and Atmospheric Administration), and the World Data Centre for Greenhouse Gases (Japan Meteorological Agency).

**The Global Warming Potential (GWP) is used to contrast different greenhouse gases and provides a simple measure of the radiative effects of various greenhouse gases relative to CO2 defined as 1. Atmospheric lifetime is used to characterize the decay of an instanenous pulse input to the atmosphere, and represents the time the input would take to decay to 0.368 (1/e) of its original value. One hundred year time horizon GWPs and atmospheric lifetimes taken from Intergovernmental Panel on Climate Change, Climate Change 2013: The Physical Science Basis, Table 8.A.1, p. 731-738. See also Recent Greenhouse Gas Concentrations (CDIAC).

Earlier versions of these pages were supported by the National Science Foundation grants DUE-9455918 and DUE-9455924.
This page created by George Lisensky, Beloit College. Last modified August 21, 2017.

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