Nobody is denying human CO2 production, just questioning your assertion that humans are responsible for the whole 40% increase.
"You do realise that the scientists can tell from the C14 and C13/C12 ratios whether the CO2 was combusted (from previously buried fossil fuels) or came from a 'natural' source, like ocean outgassing, don't you?"
I presume that you have these figures so can you enlighten us as to the human/natural ratio?
