During the Carboniferous Period, CO2 levels were 400 times what they are now.
http://www.geocraft.com/WVFossils/Carboniferous_climate.html#anchor147264
And the Jurassic was well up there too... here be dinosaurs.
I would then make the assumption that me building a fire tonight would not contribute to global warming?
The last thing I want to do is make an idiot uncomfortable.