Ice core data meaningless?

One of the arguments mooted in favour of Anthropogenic Global Warming was about the CO2 content of ice cores and it's correlation with global climate variance. Now we find a serious, peer reviewed scientific paper which clearly states the following;

The CO2 content of ancient air is directly preserved neither in the total CO2 concentration nor in the CO2 concentration in the bubbles.

So, er... all that stuff about ice cores was known to be wrong as long ago as 1977?

Hat tip to An Englishmans Castle. Pass it on.