[not a] fail

I was working on the methane question during italian (shh) and I realized that the math I was doing at midnight is pathetic. I'll fix the post later - suffice it to say that actually, methane ends up holding 2.5 times as much radiation as carbon dioxide when it's all said and done.
Oops.

Added around 5:15 later the same day:
Ok, so the final findings (according to me and my very limited research into the subject) are thus - initially, CH₄ absorbs 2.5 times the radiation as CO₂, but because of the different residence times, there comes a point where both gases flatline - and at that time, carbon dioxide is absorbing 4 times the amount of infrared radiation as methane.
With a change in time of 10 years, you get something like this (table of relative absorptions):

CH₄   CO₂
25      10
25      20 <- point of flatline for CH₄
25      30
...       ... [skip a few years]
25      80
25      90
25      100 <- point of flatline for CO₂

In this very limited view, I'm saying that the same amounts of methane and carbon dioxide are being released into the atmosphere basically once ever 10 years. Iffy, unrealistic, but it shows some interesting things. Anyway, because methane has a residence time of only 10 years, you're starting from scratch at every new entry on the table. CO₂, however, has a much longer residence time, and it builds up - only falling out of the atmosphere at the second flatline point.

I just really needed to clarify that. When I find out the actual answer to this puzzle (on Thursday), I'll do my best to post it in a timely fashion. It'll be interesting to see!!!