Changes in atmospheric CO2 and its carbon isotopic ratio during the penultimate deglaciation

A reconstruction of atmospheric carbon dioxide and its stable carbon isotopic composition from the penultimate glacial maximum to the last glacial inception

“…CO 2 data previously measured on the Vostok ice core are plotted with grey downward pointing triangles after conversion to the EDC3 age scale (Lüthi et al, 2008) for the Petit et al (1999), and with light grey stars for the Fischer et al (1999) CO 2 data. Previous data by Lourantou et al (2010b) are presented with yellow, upward pointing triangles. On a second ordinate, the δD values from the EDC ice core (black line) are plotted as proxy for Antarctic temperature evolution .…”

“…Our record consists of measurements from two Antarctic ice cores, the European Project for Ice Coring in Antarctica Dome C (EDC) and the Talos Dome ice core. The discussion of these data focuses on four main issues: (1) the critical evaluation of rapid changes in δ 13 C atm as found by Lourantou et al (2010b) at the end of the penultimate glacial/interglacial transition; (2) the similarities and differences of this work to the previously documented glacial transition from the Last Glacial Maximum (LGM) to the Holocene (Schmitt et al, 2012); (3) the 5000 yr lag of the CO 2 decline with respect to decreasing Antarctic temperature during the glacial inception at the end of MIS5.5; and (4) long-term changes of atmospheric δ 13 C atm .…”

“…1. δ 13 C atm and CO 2 measured in air trapped in ice from Dome C and Talos Dome, Antarctica over the time interval 155 000-105 000 yr BP: in (A), CO 2 (red circles) measurements on Dome C (EDC3 age scale) and on the Talos Dome (blue diamonds) ice cores (EDC3 synchronized TALDICE-1a age scale) are shown (this study). Previous data by Lourantou et al (2010b) are presented with yellow, upward pointing triangles. On a second ordinate, the δD values from the EDC ice core (black line) are plotted as proxy for Antarctic temperature evolution .…”

“…The one σ standard deviation of the MCA is highlighted by the dark grey shaded area, whereas the light grey band pictures the two σ uncertainty. Previously published δ 13 C atm measurements from the EDC ice core (Lourantou et al, 2010b) are shown in yellow upward pointing triangles. CO 2 , δD and δ 13 C atm are subdivided into six time periods ranging from I to VI (see main text for further details).…”

“…On the other hand small-scale CO 2 variations disappear quite rapidly below the BCTZ at Talos Dome and, thus, also a more efficient diffusional equilibration of potential δ 13 C variations is to be expected in this core. We also compared our data with published data for Termination II by Lourantou et al (2010b), which were also measured on the EDC ice core. A LGM value of −6.56 ‰ measured by Lourantou et al (2010a) was about 0.16 ‰ lower than our sublimation measurements with a mean δ 13 C value of −6.40 ‰ (Schmitt et al, 2012).…”