Tim Cullen has posted an interesting comment on the presence of life in ice sheets – it’s somewhat prolific as he shows here.
What this means is that the chemistry of ice sheets becomes somewhat problematic because if biological life is an active component of ice sheets, and as life on earth is also carbon based, then the presence of life and CO2 in ice sheets would present some new perspectives.
So CO2 in ice sheets cannot be assumed to be equivalent to the chemical equivalents of fossils in ice strata, and thus an accurate proxy of past CO2 levels.
This needs to be factored into any discussion about CO2 at Watts Up With That post on CO2 as a start.
And perhaps the work of Louis Kervran becomes relevant because his research indicated that “life” can alter the character of atoms and molecules – so if the ice-life system involves CO2, then I would not be too dogmatic about the validity of C12/C13 isotope ratios measured in polar ice sheets etc.
And one might also navel gaze over how to snap-freeze animals like wooly mammoths found buried in the Siberian Tundra – the trick is to kill such an animal and at the same time stop any bacterial putrefaction on death. Stopping bacterial decay is necessary to preserve the mammoth in the tundra.