Re: Wasn't this done decades ago?
>So what's actually new here?
We already use use dendro to calibrate C14 because we could measure the C14 level in each ring and correct for the variation in C14 production (due to the sun) = makes C14 more accurate.
This says that there were a couple of C14 spikes that were so obvious that if you find them in a tree ring it was exactly that year. So it give you an absolute point to peg tree ring data to for around that time - so makes tree more useful because you don't have to count back from a more modern matching sequence.