Precise 14 C ages of the Vedde and Saksunarvatn ashes and the Younger Dryas boundaries from western Norway and their comparison with the Greenland Ice Core ( GICC 05) chronology

The Greenland ice cores with the GICC05 chronology represent a standard for late Quaternary climate events and their ages, whereas many other palaeoclimatic archives are dependent on 14 C dates. It is therefore critical to know if the ice‐core and the calibrated 14 C chronologies are identical, and if not to quantify the offset between them. We present Bayesian age–depth modelling of 118 accelerator mass spectrometry 14 C dates from Kråkenes Lake, calibrated using INTCAL09, that provide high precision ages of 12 066 ± 42 and 10 210 ± 35 cal a BP for the Vedde and Saksunarvatn ashes, respectively. The lower and upper Younger Dryas boundaries have ages of 12 710 ± 52 and 11 546 ± 59 cal a BP, respectively. The four dated levels coincide with correlative levels in GICC05 within the dating uncertainties, but are all consistently younger at Kråkenes. The ages of the tephra chronostratigraphic markers suggest a mean offset of ∼70 years to older ages in the GICC05 compared with the INTCAL09 time scale. Responses to small climate changes ∼30 years before the Younger Dryas boundaries at Kråkenes are suggested to correspond to the defined Greenland Stadial 1 boundaries. This suggested difference in timing (30 years) and time scale offset (70 years) mean that the Greenland Stadial 1 boundaries appear ∼100 years older than the Younger Dryas boundaries.