The AICC2023 chronological framework and associated timescale for the EPICA Dome C ice core

Abstract. The EPICA (European Project for Ice Coring in Antarctica) Dome C (EDC) ice core drilling in East Antarctica reaches a depth of 3260 m. The reference EDC chronology (AICC2012) provides an age vs depth relationship covering the last 800 kyr (thousands of years) with an absolute uncertainty rising up to 8,000 years at the bottom of the ice core. The origins of this relatively large uncertainty are threefold: (1) the δ¹⁸O_atm, δO₂/N₂ and total air content (TAC) records are poorly resolved and discontinuous over the last 800 kyr, (2) the three orbital tools are not used simultaneously and (3) large uncertainties are associated with their orbital targets. Here, we present new highly resolved δ¹⁸O_atm, δO₂/N₂ and δ¹⁵N measurements for EDC ice core covering the last five glacial – interglacial transitions as well as novel absolute ⁸¹Kr ages. We have compiled chronological and glaciological information including novel orbital age markers from new data on EDC ice core as well as accurate firn modeling estimates in a Bayesian dating tool to construct the new AICC2023 chronology. The average uncertainty of the ice chronology is reduced from 2,500 years to 1,800 years in AICC2023 over the last 800 kyr. The new timescale diverges from AICC2012 and suggests age shifts reaching 3,800 years towards older ages over Marine Isotopes Stages (MIS) 5, 11 and 19. But, the coherency between the new AICC2023 timescale and independent chronologies of other archives (Italian Lacustrine succession from Sulmona Basin, Dome Fuji ice core and northern Alpine speleothems) is improved by 1,000 to 2,000 years over these time intervals.