"which puts the net figures at 29 GtCO2 emissions for anthropogenic and a net 17 GtCO2 (450-439+338-332) absorbtion from natural sources"

these are serious numbers.. and its accumulating while we debate.. I think its completely ridiculous to debate whats obvious..
Concerning science it is never wrong to debate what is 'obvious' ..
If people throughout the ages had taken that stance we would still believe the sun went around the earth and that the earth was flat and they'd never have bothered looking to see whether it was true or not since it was 'obvious' it couldn't be any other way.
in principle correct, in reality and practice, waste of time..
reality :we are consuming lots of hydrocarbon that produces CO2..
counter argument :no we dont
its negligible.. :-?
its like smoking in a room and saying , negligible
Yes, we're producing lots of CO2, I'm sure - I'm not debating that fact.
What I am saying is that there seem to be two schools of thought on this (of which you seem to fall into the former):
1) We 'know' for 'sure' that all this CO2 is going to 'kill' the planet because we 'know' for 'sure' that the planet can't 'cope' with all this CO2.
2) We don't know for sure whether or not the planets ecosystem can adapt and survive or whether we are having an irreversible effect on the planet.
There
is a point debating that. Like I say, if you stop debating science .. well, we would all still believe the earth was flat and the sun rotated around it.
*shrug* Personally, I don't much care for either argument surrounding 'global warming' or 'climate change' or whatever you want to call it; I'm just a tiny little man who hasn't studied for years, earned degrees and digested thousands of pages worth of scientific journal, so I do not consider myself well placed to argue either side.
But being blinkered toward either side of the climate change argument is just.. silly and, well, blinkered.