26 May 2023
 | 26 May 2023

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

Marie Bouchet, Amaëlle Landais, Antoine Grisart, Frédéric Parrenin, Frédéric Prié, Roxanne Jacob, Elise Fourré, Emilie Capron, Dominique Raynaud, Vladimir Ya Lipenkov, Marie-France Loutre, Thomas Extier, Anders Svensson, Etienne Legrain, Patricia Martinerie, Markus Leuenberger, Wei Jiang, Florian Ritterbusch, Zheng-Tian Lu, and Guo-Min Yang

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 δ18Oatm, 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 δ18Oatm, 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.

Marie Bouchet et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • CC1: 'Recommendation of AICC2023 by EPICA SSC', Eric Wolff, 30 Jun 2023
    • AC1: 'Reply on CC1', Marie Bouchet, 01 Sep 2023
  • RC1: 'Comment on egusphere-2023-1081', Anonymous Referee #1, 04 Jul 2023
  • RC2: 'Comment on egusphere-2023-1081', Anonymous Referee #2, 28 Jul 2023
  • EC1: 'Request for author response', Christo Buizert, 29 Jul 2023

Marie Bouchet et al.


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Short summary
A new federative chronology for five deep polar ice cores retrieves 800 000 years of past climate variations with an improved accuracy. Precise ice core timescales are key to study the mechanisms linking changes in the Earth’s orbit to the diverse climatic responses (temperature and atmospheric greenhouse gas concentrations). To consruct the chronology, new measurements from the oldest continuous ice core as well as glaciological modeling estimates were combined in a statistical model.