ANU > RSPhysSE > mxk121 > Research > Greenhouse

Greenhouse Gases

Atmospheric lifetime and concentration of and radiative forcing by greenhouse gases
Species Lifetime
/ year 		Concentration
/ ppb 		Radiative forcing
/ W m−2 ppm−1
Carbon dioxide CO2 356 000 0.018
Methane CH4 12 1 714 0.37
Nitrous oxide N2O 120 311 3.7
Methyl chloride CH3Cl 1.5 0.6
Methyl bromide CH3Br 1.2 0.01
Chloroform CHCl3 0.5 0.01 17
Methylene chloride CH2Cl2 0.5 0.03 30
CFC-11 CFCl3 50 0.27 280
HFC-23 CHF3 260 180
HFC-32 CH2F2 6 110
HFC-41 CH3F 4 20
HFC-125 CHF2CF3 30 200
HFC-134 CHF2CHF2 10 180
HFC-134a CH2FCF3 15 0.002 170
HFC-143 CH2FCHF2 4 110
HFC-143a CH3CF3 50 140
HFC-152a CH3CHF2 1.5 110

Radiative forcing means a change in the net downward flux of radiation at the tropopause, which is the borderline between troposphere and stratosphere. Greenhouse gases cause positive radiative forcing by absorbing the infrared radiation from the earth.

CFC: chlorofluorocarbon
HFC: hydrofluorocarbon

Concentration of CFC-11 is decreasing now, but HFCs are still used as substitutes of CFCs and their concentrations are increasing.

HFC-125 is used for industrial and commercial refrigeration.

HFC-134a is used as a foaming agent and in automobile air conditioners, commercial chillers and residential refrigerators.

HFC-143a is used for industrial refrigeration.

HFC-152a is used for industrial and commercial refrigeration and in aerosol sprays.

Reaction of HFC with O(1D)

M. Kono and Y. Matsumi, J. Phys. Chem. A 105, 65-69 (2001). [PDF]

Back to

[Top] [Research] [Mitsu Kono]