Connecting calendar ages to radiocarbon (14C) ages, i.e. constructing a calibration curve, requires 14Csamples that represent, or are closely connected to, atmospheric 14C values and that can also be independently dated. Inaddition to these data, there is information that can serve as independent tests of the calibration curve. For example,information from ice core radionuclide data cannot be directly incorporated into the calibration curve construction as itdelivers less direct information on the 14C age–calendar age relationship but it can provide tests of the quality of thecalibration curve. Furthermore, ice core ages on 14C-dated volcanic eruptions provide key information on theagreement of ice core and radiocarbon time scales. Due to their scarcity such data would have little impact ifdirectly incorporated into the calibration curve. However, these serve as important “anchor points” in time forindependently testing the calibration curve and/or ice-core time scales. Here we will show that such informationlargely supports the new IntCal20 calibration record. Furthermore, we discuss how floating tree-ring sequences onice-core time scales agree with the new calibration curve. For the period around 40,000 years ago we discussunresolved differences between ice core 10Be and 14C records that are possibly related to our limited understandingof carbon cycle influences on the atmospheric 14C concentration during the last glacial period. Finally, we reviewthe results on the time scale comparison between the Greenland ice-core time scale (GICC05) and IntCal20 thateffectively allow a direct comparison of 14C-dated records with the Greenland ice core data.
- ice core