How Much are Ozone Depleting 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 image for graphs
Ozone Depleting Potential**
Atmospheric lifetime (years)**
Carbon dioxide
CO2
link
link
ppm
link
long term
0
300-1000***
Methane
CH4
link
link
ppb
link
long term
0
11.8
Nitrous oxide
N2O
link
link
ppb
link
long term
0.017
109
Ozone
O3
link
link
ppb
link
Total column (Dobson)
hours-days
Hydrogen
H2
link
link
ppb
0
1-2
Carbon monoxide
CO
link
link
ppb
0
0.25
Trichlorofluoromethane
CCl3F
CFC-11
link
link
ppt
1
52
Dichlorodifluoromethane
CCl2F2
CFC-12
link
link
ppt
0.75
102
1,1,2-Trichloro-1,2,2-trifluoroethane
CCl2FCClF2
CFC-113
link
link
ppt
0.82
93
Carbon tetrachloride
CCl4
R-10
link
link
ppt
0.87
32
Carbon tetrafluoride
CF4
PFC-14
link
link
ppt
0
50,000
Chloroform
CHCl3
R-20
link
link
ppt
0.01
0.501
Chlorodifluoromethane
CHClF2
HCFC-22
link
link
ppt
0.038
11.6
Fluoroform
CHF3
HFC-23
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link
ppt
0
228
Dichloromethane
CH2Cl2
R-30
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link
ppt
0.004
0.493
Difluoromethane
CH2F2
HFC-32
50% of R-410A
link
link
ppt
0
5.4
Methyl chloride
CH3Cl
Chloromethane
R-40
link
link
ppt
0.015
0.9
Methyl bromide
CH3Br
Bromomethane
link
link
ppt
0.66
0.8
1,2-Dichloro-1,1,2,2-tetrafluoroethane
CClF2CClF2
CFC-114
link
link
ppt
0.53
189
Chloropentafluoroethane
CClF2CF3
CFC-115
link
link
ppt
0.45
540
Hexafluoroethane
CF3CF3
PFC-116
link
link
ppt
0
10,000
Methyl chloroform
CH3CCl3
1,1,1-Trichloroethane
R-140a
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link
ppt
0.12
5
1,1-Dichloro-1-fluoroethane
CH3CFCl2
HCFC-141b
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link
ppt
0.102
9.4
1-Chloro-1,1-difluoroethane
CH3CClF2
HCFC-142b
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ppt
0.057
17.1
1,1-Difluoroethane
CH3CHF2
HFC-152a
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link
ppt
0
1.6
1,1,1-Trifluoroethane
CH3CF3
HFC-143a
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link
ppt
0
51
1,1,1,2-Tetrafluoroethane
CH2FCF3
HFC-134a
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link
ppt
0
14
Pentafluoroethane
CHF2CF3
HFC-125
50% of R-410A
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link
ppt
0
30
Tetrachloroethene
Cl2C=CCl2
Perchloroethylene
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link
ppt
0.007
0.301
Propane
CH3CH2CH3
R-290
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link
ppt
0
0.036
Sulfur hexafluoride
SF6
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ppt
0
1,000
Less than 5 ppt
1,1,1,3,3-Pentafluoropropane
CHF2CH2CF3
HFC-245fa
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link
ppt
0
7.9
Bromochlorodifluoromethane
CBrClF2
Halon-1211
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link
ppt
7.1
16
Nitrogen trifluoride
NF3
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link
ppt
0
569
Bromotrifluoromethane
CBrF3
Halon-1301
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link
ppt
17
72
Chlorotrifluoromethane
CClF3
CFC-13
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link
ppt
0.3
640
Sulfur dioxide difluoride
SO2F2
link
link
ppt
36
1,1,1,2,3,3,3-
Heptafluoropropane
CF3CFHCF3
HFC-227ea
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link
ppt
0
36
Perfluorocyclobutane
C4F8
PFC-318
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link
ppt
0
3200
1,1,1,3,3-Pentafluorobutane
CF3CH2CF2CH3
HFC-365mfc
link
link
ppt
0
8.9
Perfluoropropane
CF3CF2CF3
PFC-218
link
link
ppt
0
2600
1,2-Dibromotetrafluoroethane
CBrF2CBrF2
Halon-2402
link
link
ppt
15.7
28
2-Chloro-1,1,1-trifluoroethane
CH2ClCF3
HCFC-133a
link
link
ppt
0.019
4.6
1,1,1,3,3,3-Hexafluoropropane
CF3CH2CF3
HFC-236fa
link
link
ppt
0
213
1,2-Dichloro-1,1-difluoroethane
CH2ClCClF2
HCFC-132b
link
link
ppt
0.038
3.5
1,1,1,2,2,3,4,5,5,5-Decafluoropentane
CF3CHFCHFCF2CF3
HFC-4310mee
link
link
ppt
0
17
2,3,3,3-Tetrafluoropropene
CF3CF=CH2
HFO-1234yf
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<1 ppt
(decomposes to
CF3COOH)
0
0.033
Trifluoromethyl sulfur pentafluoride
CF3SF5
link
link
ppt
0
800
ppm = parts per million (106), ppb = parts per billion (109), ppt = parts per trillion (1012), ppq = parts per quadrillion (1015).

Information about Sampling Sites.

*Concentration data from the Scripps CO2 Program, the Advanced Global Atmospheric Gases Experiment (NASA), Global Greenhouse Gas Reference Network and Long-term global trends of atmospheric trace gases (Global Monitoring Laboratory, U. S. National Oceanic and Atmospheric Administration), Cape Grim Australia Greenhouse Gas Data (CSIRO), and the World Data Centre for Greenhouse Gases (Japan Meteorological Agency and the World Meteorological Organization).

**The Ozone Depletion Potential (ODP) is used to contrast different gases and provides a simple measure of the expected impact on ozone per unit mass emission of a gas relative to that caused by CFC-11 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. ODP values from World Meteorological Organization, Scientific Assessment of Ozone Depletion: 2018, Table A-1 and United States Environmental Protection Agency, Ozone-Depleting Substances. Atmospheric lifetimes taken from Intergovernmental Panel on Climate Change, Climate Change 2021: The Physical Science Basis, Table 7.SM.6, p. 16-27.

***IPCC no longer lists a value for the carbon dioxide lifetime. It depends on the biosphere and concentration-dependent equilibria between the atmosphere, the ocean, and deposition of CaCO3 on timescales of a few centuries. See Annu. Rev. Earth Planet. Sci. 37:117-34 (2009) and The Atmosphere: Getting a Handle on Carbon Dioxide (NASA 2019).

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 July 25, 2025.

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