>"Today's CO2 concentration of around 400 ppm exceeds the natural variability seen over hundreds of thousands of years,"[0]

That's the part that opens and shut's the "debate" surrounding human-cause climate change. When you have that much data, combined with the fact that we build and use machines that spew carbon there can not be any other explanation for the Co2 levels. Case closed.

[0]: http://www.independent.co.uk/environment/carbon-dioxide-co2-...