Except correlation doesn't prove causation. How many times does this have to be stated for people to understand this? The number of pirates is perfectly inversely correlational to the atmospheric CO2. Is it pretty clear that one causes the other?

Sediment cores and being able to extrapolate data going back thousands or millions of years is a theory only. No one can state CO2 levels going back thousands of years with any level of certainty, certainly not in the Ppm accuracy.