2007-06-14 16:11:16 · 3 answers · asked by billnzan 4 in Environment ➔ Global Warming
In order of importance:
water, CO2, methane, halocarbons (CFCs are an example), nitrous oxide.
Nice picture on page 4 of this report:
http://www.ipcc.ch/SPM2feb07.pdf
Water vapor isn't included because the "water cycle" closely regulates the amount of warming caused by it, and so it is not important in global warming.
2007-06-14 17:10:00 · answer #1 · answered by Bob 7 · 1⤊ 0⤋
Almost all anthropogenic global warming is caused by 8 greenhouse gases, I've listed them below using different methods of measuring their contribution to global warming. There's many more GHG's which I've included as 'all others'.
BY CONTRIBUTION TO GLOBAL WARMING
Takes account of quantity, effectiveness etc. Shows as a %age how much each gas contributes to overall anthropogenic global warming
Carbon Dioxide - 72.294%
Nitrous Oxide - 18.409%
Methane - 7.949%
Dichlorodifluoromethane - 0.897%
Trichlorofluoromethane - 0.212%
Tetrafluoromethane - 0.103%
1,1,1-Trichlorotrifluoroethane - 0.083%
Tetrachloromethane 0.036%
All Others - 0.015%
BY ATMOSPHERIC CONCENTRATION
Measured in parts per trillion by volume
Carbon Dioxide - 365,000,000
Methane - 1,745,000
Nitrous Oxide - 313,000
Dichlorodifluoromethane - 533
Trichlorofluoromethane - 268
Tetrachloromethane - 102
1,1,1-Trichlorotrifluoroethane - 84
Tetrafluoromethane - 80
All others - 152
BY RADIATIVE FORCING
(Positive warming effect less negative warming effect), measured in Watts per square metre
Carbon Dioxide - 1.46
Methane - 0.48
Dichlorodifluoromethane - 0.17
Nitrous Oxide - 0.15
Trichlorofluoromethane - 0.07
1,1,1-Trichlorotrifluoroethane - 0.03
Tetrachloromethane - 0.01
Tetrafluoromethane 0.003
All others - average of 0.05
BY GLOBAL WARMING POTENTIAL
Measures how effective each gas is at retaining heat, the scale uses carbon dioxide as 1. The figures are given show the effectiveness after 100 years.
Dichlorodifluoromethane - 8500
Tetrafluoromethane - 6500
1,1,1-Trichlorotrifluoroethane - 5000
Trichlorofluoromethane - 4000
Tetrachloromethane - 1800
Nitrous Oxide - 296
Methane - 23
Carbon Dioxide - 1
All others - Average 500
Excluded from the list is water vapour, this is almost entirely natural. If it were included then it's overall contribution is approximately 62%, atmospheric composition varies but averages around 1%, RF is almost 0, GWP is about 0.05
Related technical stuff here
http://www2.mst.dk/common/Udgivramme/Frame.asp?pg=http://www2.mst.dk/Udgiv/publications/2005/87-7614-570-0/html/kap04_eng.htm
2007-06-15 15:55:27 · answer #2 · answered by Trevor 7 · 0⤊ 0⤋
"Water vapor constitutes Earth's most significant greenhouse gas, accounting for about 95% of Earth's greenhouse effect."
2007-06-15 02:01:00 · answer #3 · answered by Matt 2 · 0⤊ 1⤋