muf.
Guess I owe you a better explanation now that I’ve researched the graph that you linked.
The source of your graph isn’t exactly what I would call a credible source.
http://www.oism.org/pproject/s33p36.htm
Yes, even a .gif image usually reveals its source page on the web, but that’s not to say that the graph isn’t accurate, only that its source may be brought to question.
You ought to realise that internal politics within the climate fraternity places a question mark on temps for this time period. A look at the CA main blog only shows this too well.
http://www.climateaudit.org/?p=7411#more-7411
There are certainly questions that need to be answered as to the vertical polarity of some important images (among other things).
You seem to place importance on anthropogenic CO2. Where I’m concerned, the ‘warming’ properties of CO2 are no longer up for debate. Without the radiative atmospheric gasses all atmospheric heat transfer would rely on convection, which means that Earth would be subjected to more advection (winds) as well. Where CO2 absorbs, it also emits in more than one direction. Thus, it moves heat without the need for the dispersion of any atmospheric mass. IOW, it aids the cooling of atmospheric mass.
Perhaps a better outlook would be to understand a bit about palaeoclimatology. Doug L. Hoffman has a blog where he is trying to improve his book sales.
http://theresilientearth.com/?q=content/grand-view-4-billion-years-climate-change
That’s his ‘Grand View’, but nearly half way down the page you’ll find a graph describing global temp over the ages. It isn’t a finely dated graph, but it shows what we may well be expected to encounter. There’s also a CO2 graph there (notice that the graphs are all at roughly the same time scale). Doug needs to be ‘credible’ for his book sales, so feel free to browse the rest of the site.
Best regards, suricat.