Suppose the ice core data is not calibrated in amplitude to direct measurement. We are talking parts per million.
I understand there have been trouble calibrating it. The late 19th century and early 20th century direct measurements tend to disagree drastically varying from 280 to 550.
So we are left with no direct verification that the amplitudes of such measurements will match.
The late 19th century and early 20th century direct measurements tend to disagree drastically varying from 280 to 550.Are you getting that from Zbigniew?
The older ice core data is congruent with the newer ice core data (different sites) and shows that at the end of the Younger Dryas -- official initiation of the Holocene -- CO2 in the atmosphere was about 280 ppm. Anything substantially above that (+15 ppm or higher) until "agriculturalization" in the early 1700s, when there was the beginning of increase due to land-use alteration, should be discarded as incorrect.
