From Envirowiki

Atmospheric carbon levels are one of the regulators of the earth's temperature, via the greenhouse effect. atmospheric cabron generally refers to carbon dioxide and methane since they are the most important greenhouse gasses, however there are other GHGs without carbon in them.

Atmospheric carbon levels have sat at around 280ppmv since the last ice age. Since the industrial revolution, levels have grown exponentially due to combustion of fossil fuels, and currently sit at 383ppmv, about 35% higher than natural levels, and the highest in the last 650,000 years^[1].

[edit] references

1. ↑ Global Carbon Project (2008-09-26) Carbon Trends 2007 . Report. Retrieved on 2008-09-26.