Alternatives to radiocarbon dating
Beginning in the 1990s, a coalition of researchers led by Paula J.
Reimer of the CHRONO Centre for Climate, the Environment and Chronology, at Queen's University Belfast, began building an extensive dataset and calibration tool that they first called CALIB.
Reimer and colleagues point out that Int Cal13 is just the latest in calibration sets, and further refinements are to be expected.
For example, in Int Cal09's calibration, they discovered evidence that during the Younger Dryas (12,550-12,900 cal BP), there was a shutdown or at least a steep reduction of the North Atlantic Deep Water formation, which was surely a reflection of climate change; they had to throw out data for that period from the North Atlantic and use a different dataset.
The radiocarbon dating method is based on the fact that radiocarbon is constantly being created in the atmosphere by the interaction of cosmic rays with atmospheric nitrogen.
The half-life of an isotope like C14 is the time it takes for half of it to decay away: in C14, every 5,730 years, half of it is gone.
So, if you measure the amount of C14 in a dead organism, you can figure out how long ago it stopped exchanging carbon with its atmosphere.
The latest curves were ratified at the 21st International Radiocarbon Conference in July of 2012.
Within the last few years, a new potential source for further refining radiocarbon curves is Lake Suigetsu in Japan.
Lake Suigetsu's annually formed sediments hold detailed information about environmental changes over the past 50,000 years, which radiocarbon specialist PJ Reimer believes will be as good as, and perhaps better than, samples cores from the Greenland Ice Sheet. report 808 AMS dates based on sediment varves measured by three different radiocarbon laboratories.