Comment Annual increase in CO2 (Score 1) 367
Also, it should be noted that the current annual increase in CO2 is about 2 ppm, which this graph shows. And, as can be read here(in danish), the largest fluctuations in the period from A.D. 1000 - 1800 was 7 ppm.
So at present we are increasing CO2 levels every four years by more than the biggest fluctuations in said time period; I'm guessing it really is man-made.