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Main greenhouse gases
Pre-industrial Concentration
Atmospheric
Gas name concentration
Main human
in 1998
lifetime
GWP **
( ppmv * )
activity source
( ppmv )
(years)
Water vapour
1 to 3 1 to 3 a few days - -
Carbon dioxide
Fossil fuels, cement prod-
(CO
280 365 variable
2
)
uction, land use change
1
Methane
Fossil fuels, rice paddies
(CH
0.7 1,75 12
4
)
waste dumps, livestock
21
Nitrous oxide
Fertilizers, combustion
(N
0.27 0,31 114
2
O

)
industrial processes
310
HFC 23 (CHF
3
)
0 0,000014 250 Electronics, refrigerants 12 000
HFC 134 a
(CF
00,0000075 13.8 Refrigerants 1 300
3
CH
2
F)
HFC 152 a
(CH
0 0,0000005 1.4 Industrial processes 120
3
CHF
2
)
Perfluoromethane
(CF
0,0004 0,00008 >50 000 Aluminium production 5 700
4
)
Perfluoroethane
(C
00,000003 10 000 Aluminium production 11 900
2
F
6
)
Sulphur
hexafluoride (SF
0 0,0000042 3 200 Dielectric fluid 22 200
6
)
* ppmv = parts per million by volume ** GWP = Global warming potential (for 100 year time horizon).
Present changes, causes and observed impacts 19
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