[voltaire]

CO2 in atmosphere= 400ppm (400/1,000,000).
Man responsible for .03% = 12ppm (12/1,000,000).
USA responsible for 17% of man made CO2 = 2 ppm (2/1,000,000).

INSIGNIFICANT!

[the_Watchman]

It should be 12 / 400 = 3%. Not .03%

[palmer]

CO2 in atmosphere= 400ppm (400/1,000,000).
Man responsible for .03% = 12ppm (12/1,000,000).

Before man the CO2 was 280, now 400, so we create most of the 120ppm. The reason I say most is that there would have been some natural rise in CO2 due to the natural temperature rise starting in the mid 1700's. That rise would have taken us to 290 or so, not to 400. So the rest is manmade.