It is amazing that the global warming freaks (The ones who think humans are causing it) make such crazy assertions as to suggest that we are responsible for global temperature changes.
Its like saying that humans cause the average temperature at 3pm to be warmer than at 3am.
Or that humans cause the average temperature in August to be warmer than the average temperature in February. (in the No Hem)
Just plain crazy..but I guess if you make it hard enough to disprove, you can make any crazy assertion.
I dunno, I think it could be lack of plants. They put out O2, so it's probably the destruction of the rain forests more than anything. /s