[Ruy Dias de Bivar]

Posh! I remember when the key word was THE GREEN HOUSE EFFECT!

[Jack Hydrazine]

Greenhouse Effect
http://en.wikipedia.org/wiki/Greenhouse_effect

By their percentage contribution to the greenhouse effect on Earth the four major gases are:[21][22]

water vapor, 36–70%
carbon dioxide, 9–26%
methane, 4–9%
ozone, 3–7%
The major non-gas contributor to the Earth’s greenhouse effect, clouds, also absorb and emit infrared radiation and thus have an effect on radiative properties of the atmosphere.[22]

[expat2]

Actually, the greenhouse effect is nothing to do with IR absorption. Vertical convection is blocked physically by the glass roof, and that's why greenhouses warm up. (Even climate scientists accept that).
It is worth noting that there is a "greenhouse roof" in the Earth's atmosphere, too -- the lower-stratosphere inversion blocks warm air from escaping and forces it to move away from the equator toward the poles, thereby keeping the mid-latitudes livable.