I have yet to have explained to me how humans, putting 0.0012% of a trace gas that makes up .04% of the atmosphere, can/is causing globull warming.
Regarding your percentages: It's true is only 0.04% but it was only 0.028 percent around 1850. The amount we added took it from about 0.03% to 0.04% (part of the rise was natural). There's bound to be some warming from that, but not more than I would consider beneficial especially since the CO2 warming is greatest in Siberia, northern Canada, etc. in winter and at night.