I dont know of anyone who disagrees with this. We measure c02 in parts per million, and methane in parts per billion.
If, in fact, c02 is the climate temp control mechanism, I could understand espola's hysterical claim that a large portion of the earth's population will be wiped out by its increase.
I tend to believe c02 is a bit player, like one of the pumpkins off the stage in the school halloween play, and the net effect is negligible, if measurable at all.
The atmosphere doesn't care what you believe.