I may have inadvertently had a hand in this millennium graph! I recall getting a fax from Jack with a hand-drawn graph, that he asked me to review. Where he got his version from, I don't know. I think I scribbled out part of the line and amended it in some way, but have no recollection of exactly what I did to it. And whether he edited it further, I don't know. But as it was purely schematic (& appears to go through ~1950) perhaps it's not so bad. I note, however, that in the more colourful version of the much embellished graph that Stefan circulated ([1] http://www.politicallyincorrect.de/2006/11/klimakatastrophe_was_ist_wirkl_1.html the end-point has been changed to 2000, which puts quite a different spin on things. They also seem to have fabricated a scale for the purported temperature changes. In any case, the graph has no objective basis whatsoever; it is purely a "visual guess" at what happened, like something we might sketch on a napkin at a party for some overly persistent inquisitor..... (so make sure you don't leave such things on the table...).
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CO2 is, by definition, a greenhouse gas...but a very poor one.
One of my “side” hobbies is Astronomy. I came across a page where someone had calculated what it would take to increase Mars’ temperature (and eventually oxygen) to atmosphere to make it habitable. Mars is 95% CO2, but very thin, but still more CO2 total mass than Earth has...yet it’s bitter cold.
Adding enough N2 and O2 to make an earth-like atmosphere that would consist of 80% N2, 19.4% O2, and 0.6% CO2(assuming it could be done) warmed the planet up a lot more than doubling CO2 but adding nothing else. Furthermore, the N2/O2 atmosphere only warmed less than a degree even doubling the CO2 from there from 0.6% to 1.2%...
In other words, the THICKNESS of the atmosphere had a LOT more effect than the composition. Obviously this is all speculative, and based on modeling...
If this is all true, then increasing Earth’s CO2 from 0.29% to 0.35% can’t have more than a minimal effect, IMHO.