This aggravates the hell out of the minions of the Great and Powerful Carbon. The primary law of the human part of the universe is Murphy's. People screw up. So with the typical irrational comments on Climate Etc. concerning CO2 and "closing" the Mass Balance, here is a little illustration.
It is interesting because until mankind started burning demon coal it should have been a downward trend. Now I have removed the industrial part of the Law Dome data because I want to focus on this pre-industrial period.
Some suspect that this discrepancy is due to "natural" smoothing or diffusion of CO2 in the Antarctic ice and snow that creates the CO2 record. That smoothing would reduce peaks/valley amplitude and shift the CO2 record so that it lags temperature. Real scientists know that you should check to make sure there isn't bird shit on your radio telescope antenna and that you thermocouples are not self heating before you announce your unprecedented discoveries to the world, Murphy's Law.
This particular discrepancy may not amount to a hill of beans or it might be something. It could be useful for say pointing out other scientists that might have bird shit in their methods.
There are some young up and comers in the paleo ocean field we might want to check.
I think Murphy's Law has bitten someone in the butt.