I have never found a useful overview of how paleo people look at CO2 and not for lack of trying.
So I'm happy to see that Richard Alley is giving a plenary talk on this very subject at AGU Tuesday afternoon 1:40 PM Pacific time..
Title is "The Biggest Control Knob: Carbon Dioxide in Earth's Climate History".
It will be webcast. Google AGU webcast and you should find it.
The only thing we can be sure of about the future is that it will be absolutely fantastic. So if what I say now seems to you to be very reasonable, then I have failed completely. Only if what I tell you appears absolutely unbelievable, have we any chance of visualizing the future as it really will happen.
- Arthur C. Clarke (h/t Brin)