If a large percentage of CO2 is created by living organisms and as the planet starts to warm up and organisms starts to multiple, is it right to assume that this is the cause for the CO2 lag with the temperature?
The rise in CO2 is mainly because of warming oceans. As a solution warms, less dissolved gas can be held within it. This is why you see small bubbles rising in a pot before you reach boiling temperature: it is not water vapor, it is air that was dissolved in the water being forced out.
The oceans hold huge amounts of CO2, much more than what's contained in the atmosphere, so even a small temperature change can lead to a significant change in atmospheric concentrations.
Originally Posted by
seattlite 
Is CO2 known to shield or insulate the planet from the sun during the down slope of an ice age? If so, it is right to assume as the CO2 level goes down enough to where it can't insulate the planet from the sun rays, the planet will warm up again.
CO2 always works to keep the planet warmer than it otherwise would be.
Try thinking of it like this: imagine you're starting at equilibrium, with CO2 levels constant and the orbital tilt that triggers ice ages constant as well. Assuming that these are the only two factors, you'd expect temperatures to stay constant, right?
Now imagine that the orbital tilt changes, which has the effect of making the planet cool slightly. This means more CO2 can be absorbed by the oceans, and so atmospheric concentrations go down. This will then also have the effect of lowering temperatures, and so the decline in CO2 acts to reinforce the cooling signal from the orbital variations. Declining CO2 levels are thus acting as a 'feedback' just as rising CO2 levels did when the orbital cycles were warming us out of the ice age.
