Thanks for the welcome, and thank you for responding the way you did (rather than the way you responded to RicS, perhaps there is a history there that I'm not aware of).

As far as the link that you provided, I'm not sure it actually investigated whether there was a time lag between CO2 and temperature. If you would have quoted the entire sentence, people could see that the authors were quoting previous work, not the work associated with the paper itself.

"According to Barnola et al. (1991) and Petit et al. (1999) these measurements indicate that, at the beginning of the deglaciations, the CO2 increase either was in phase or lagged by less than ~1000 years with respect to the Antarctic temperature, whereas it clearly lagged behind the temperature at the onset of the glaciations. "

The papers I linked investigated timing using the actual Vostok data and found a time lag as documented by the following.
"High-resolution records from Antarctic ice cores show that carbon dioxide concentrations increased by 80 to 100 parts per million by volume 600 ? 400 years after the warming of the last three deglaciations."

and

"The sequence of events during Termination III suggests that the CO2 increase lagged Antarctic deglacial warming by 800 ? 200 years and preceded the Northern Hemisphere deglaciation."

Regardless, we have 3 studies, 2 of the studies specifically looked for time lags, and found them. Both in the 600-800 year range. The study that was only concerned with extracting the time series of both variables said that the relationship was either in phase, or lagged by less than 1000 years. Based on the outcomes of these 3 studies, I'd be inclined to say there's a definite lag.



But I have to take issue with your statement that "its relevance, either way, is unproven" Huh? Am I missing something? Evidence has been found that historic temperature increases lead historic CO2 increases, and you're not sure if it's relevant?

The entirety of global warming science is based on the key assumption that increased CO2 causes temperature to increase (which was validated by looking at the correlation of CO2 and temp within these very same ice cores). All of the GCMs use this basic assumption.

If CO2 lags temperature, this assumption falls apart. The cause and affect relationship that everybody has bet on, would be wrong. It would be reversed! Temperature would be the causation factor for increases to CO2(historically).

I would say that is very relevant.