To what extent does emissions of carbon dioxide by humanity have on global warming?

Answer 1

There's not really a good answer to this question. Regardless of whether you are predisposed to wanting a large number or a small number, here is a pretty good treatment of the topic:

http://tinyurl.com/z35mf

What is known is that of the anthropogenic climate forcings that are positive (i.e., leading to warming), CO2 is by far the largest. However, trying to assign x% of the observed warming to the forcing from CO2 is essentially a meaningless exercise for the reasons given in the link above. The IPCC has studiously avoided this kind of thing as well: attribution of fractions of warming due to different forcing mechanisms do not appear in the AR4 WG1 SFP available at

http://tinyurl.com/2r29ku

Answer 2

Who knows ?

There is some good evidence that atmospheric CO2 is a function of temp., however the timescale involved (last 100 years) is insignificant ... to really be sure we need data over at least 20,000 years ..

NB. Al Gore's graphs look a lot less convincing if you plot them on the same time-line (which shows the temp change comes first and the CO2 comes second ..) instead of 'shifting' the CO2 graph back 50 years (so it looks like the CO2 change causes the temp rise) ...
so here's a good one :-

"How can you tell when a Politician is lieing ?"

ans: ... his lips are moving ...

Answer 3

Good Q, Peter, this is in my 'Watch List'.
Tks
Le7