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The researchers claim that the work is a step closer towards the ‘Holy Grail’ of carbon dating – precisely refining the calibration of carbon-14 against a calendar timescale so that dating of historical treasures can become ever more accurate.
Carbon dating of artefacts is possible because radioactive carbon-14 is continually created in the upper atmosphere.
But tree ring data only goes back around 13,000 years.
Extending the calibration of atmospheric carbon-14 to be able to date items up to 54,000 years old – based on carbon-14’s 5730 year half-life – has been challenging, however.
They say their study helps refine and calibrate the atmospheric radiocarbon record and provides insights into the causes of variations in atmospheric radiocarbon over time.The results help explain historic variations in atmospheric radiocarbon and could add clarity to geological events such as the Laschamp geomagnetic excursion.This was a brief reversal of the Earth’s magnetic field around 43,000 years ago.As levels of carbon-14 in the atmosphere fluctuate over time, to enable accurate dating the atmospheric carbon-14 record needs to be calibrated against a calendar time-scale.Tree rings provide some of the best information on historic radiocarbon levels, as trees take carbon dioxide directly from the atmospheric and turn it into cellulose with little delay.