Measurements of stable carbon isotope ratios of CO2 over the last 24000 years and CO2 concentration measurements on Antarctic ice cores using three different methods

DOI

The stable carbon isotope ratio of atmospheric CO2 (d13Catm) is a key parameter in deciphering past carbon cycle changes. Here we present d13Catm data for the past 24,000 years derived from three independent records from two Antarctic ice cores. We conclude that a pronounced 0.3 per mil decrease in d13Catm during the early deglaciation can be best explained by upwelling of old, carbon-enriched waters in the Southern Ocean. Later in the deglaciation, regrowth of the terrestrial biosphere, changes in sea surface temperature, and ocean circulation governed the d13Catm evolution. During the Last Glacial Maximum, d13Catm and atmospheric CO2 concentration were essentially constant, which suggests that the carbon cycle was in dynamic equilibrium and that the net transfer of carbon to the deep ocean had occurred before then.

The ice cores were analyzed in three different laboratories which each lab uses a dedicated, independent analytical system referred to as Bern sublimation, Bern cracker and Grenoble mill data. The names of the different methods are composed of the University (Grenoble and two groups at Bern) and an identifier of the special extraction system ('ball mill', 'cracker', 'sublimation'). In short, the three methods involve the following analytical steps:First, enclosed atmospheric air from the ice sample is released using a dedicated extraction device (sublimation, needle cracker and a ball mill for the respective data sets: Bern sublimation, Bern cracker and Grenoble mill). In a second step, the CO2 from the released ice core air is separated from the bulk air (N2, O2 and Ar) using cryogenic trapping. Third, a gas chromatographic column purifies the CO2 sample from other trace gases such as N2O. Finally, the stable carbon isotopic ratio of the CO2 sample is measured against a bracketing standard using an isotope ratio mass spectrometer. The typical measurement reproducibilities of the three methods are 0.05 permil - 0.07 permil for the Bern sublimation, 0.07 permil for the Bern cracker, and 0.10 permil for the Grenoble mill data set.

Supplement to: Schmitt, Jochen; Schneider, Robert; Elsig, Joachim; Leuenberger, Daiana; Lourantou, Anna; Chappellaz, Jérôme A; Köhler, Peter; Joos, Fortunat; Stocker, Thomas F; Leuenberger, Markus Christian; Fischer, Hubertus (2012): Carbon isotope constraints on the deglacial CO2 rise from ice cores. Science, 336(6082), 711-714

Identifier
DOI https://doi.org/10.1594/PANGAEA.772713
Related Identifier https://doi.org/10.1126/science.1217161
Metadata Access https://ws.pangaea.de/oai/provider?verb=GetRecord&metadataPrefix=datacite4&identifier=oai:pangaea.de:doi:10.1594/PANGAEA.772713
Provenance
Creator Schmitt, Jochen ORCID logo; Schneider, Robert; Elsig, Joachim; Leuenberger, Daiana; Lourantou, Anna; Chappellaz, Jérôme A; Köhler, Peter ORCID logo; Joos, Fortunat ORCID logo; Stocker, Thomas F ORCID logo; Leuenberger, Markus Christian ORCID logo; Fischer, Hubertus ORCID logo
Publisher PANGAEA
Publication Year 2012
Funding Reference Fifth Framework Programme https://doi.org/10.13039/100011104 Crossref Funder ID EVK2-CT-2000-00077 https://cordis.europa.eu/project/id/EVK2-CT-2000-00077 European Project for Ice Coring in Antarctica; Fourth Framework Programme https://doi.org/10.13039/100011105 Crossref Funder ID ENV4980702 https://cordis.europa.eu/project/id/ENV4980702 European Project for Ice Coring in Antarctica
Rights Creative Commons Attribution 3.0 Unported; https://creativecommons.org/licenses/by/3.0/
OpenAccess true
Representation
Language English
Resource Type Supplementary Publication Series of Datasets; Collection
Format application/zip
Size 6 datasets
Discipline Earth System Research
Spatial Coverage (123.350W, -75.100S, 159.183E, -72.817N); Antarctica