In my searches I came across items about ice-cores..
I was just reading a pdf: "180 Years accurate CO2 - Gasanalysis of Air
by Chemical Methods (Short version)"..
There seems to be a big difference between Ice-core CO2 measurements
and those made over many years, using other collection methods.
There is also this item, waiting to be read..
Antarctic Ice Cores: The Sample Rate Problem | Watts Up With That?
'the merits of ice cores vs. plant stomata as paleo-CO2 measurements. '
Almost midnight..
Later..