Re: pointless stupidity
A couple of points:
Absent any greenhouse effect, the Earth would on average be about 30 degrees C colder than it is now. It's not that hard to do the basic calculation, which is why the greenhouse effect was discovered in the 19th century. Calculating the proportion of anthropogenic impact on the greenhouse effect as a whole is misleading, because we only need to move it by a few percentage points to create a very large swing in average surface temperature.
I don't know where you get your 3% number for anthropogenic contribution to atmospheric CO2. Or are you quoting some other number? The pre-industrial level of atmospheric CO2 was about 300ppm. It's now about 400ppm, all of which is us. The natural sources of CO2 emission are in equilibrium with natural sources of absorbtion. The bottom line is that we've moved the level by 30%, and are moving it at an increasing rate.