A head banger for some, not others...What would be the predominate GHG if there was no oxygen?

Question

Just for the fun of it.

Answer 1

Methane maybe...

If oxygen didn't exist, then there could be no carbon dioxide (CO2), carbon monoxide (CO), ozone (O3), or nitrogen dioxide (NO2)

If I remember back to my environmental chemistry days methane (CH4) is a greenhouse gas.

Answer 2

wtf?

Answer 3

I'm going to guess you believe you can't make methane without oxygen.  Therefore, I'm going with ammonia since it has a lot of infrared bands in the right places, was found in relatively high concentrations in primordial anoxic atmospheres, and nobody has mentioned it yet.  

Answer 4

NH3 is a good and plausible answer.  I think that H2S is also a plausible major atmospheric constituent in the absence of oxygen.  The absorption bands are in the 4.2 and 8 micron regions.  The 8 micron band overlaps the black body radiation of the earth.  

Phys. Rev. 34, 604 - 610 (1929)

Some of the freons are very potent greenhouse gasses.  If I wanted to engineer a warm planet without oxygen, I would start with CF2Br2 (and other haloalkanes)  because it has strong absorptions in the middle of the earth's thermal radiation band.

http://www.cstl.nist.gov/div838/g4/spect...

Answer 5

Without oxygen the predominant naturally occurring GHG would be Methane.

Answer 6

Depends on what the hypothetical atmospheric chemistry IS, rather than just what it is not.

But the principal GHG in our atmosphere that contains no oxygen, is indeed methane.

Answer 7

Carbon Dioxide!!!