Its nice to see the big guys giving quotes on Pearson et al's results, and they do make very important points. This does indeed have to be replicated in an independent lab, since it is always possible that there is some systematic error within the radiocarbon lab of the study. That said, it is noted in the paper that the lab has shown no bias in recent inter-laboratory comparisons. This latter point is important, since what it means is that exercises performed upon the same test sample across different labs have shown no discrepancies (with experimental uncertainties).

Bronk-Ramsey makes a very valid point which leads into the point by Sturt Manning. The point is that the radiocarbon ages of archaeological samples from archaeological sites are not in question , only the calibrated date. So if a piece of wood from a site has a radiocarbon age of 3315 +/- 20 then that will not change. Only the calibrated calendar date will change depending upon the shape of teh calibration curve used.

Which brings us to Manning's point. It has been a particular sticking point that archaeologists have completely disregarded radiocarbon dates for the Thera eruption because they appear to old with respect to their own chronological frameworks. Often they are dismissed with ad hoc arguments to explain away the discrepancy between the radiocarbon dates and their chronologies. This has often relied upon attacking the radiocarbon age of samples, with claims of volcanic inert carbon offsets, or other forms of contamination. A fear then is that one could ask the question "if the calibration curve is wrong, then why should we trust any radiocarbon age or date?".

I think this is a little pessimistic. This study potentially resolves the issues between radiocarbon and archaeology dating of Thera. Manning et al have recently published evidence that shows that seasonality and climate can cause shifts in the measured radiocarbon age (and hence calibrated date) of known date samples from the Levant, the reason being is that these samples are growing in different radiocarbon reservoirs at different times of the year, and that these reservoirs may differ from the reservoirs that immerse European Oak and Bristlecone pine that underpin most of the Northern Hemisphere radiocarbon calibration curve. So the threat of others dismissing radiocarbon ages has already been an issue.

To me the most interesting question resulting from Pearson et al is this: If the calibration curve is in error between 1660-1500 BC, is it in error anywhere else?

Jonny

The path to good scholarship is paved with imagined patterns. - David M Raup