Understanding the role of atmospheric CO2 during past climate changes requires clear knowledge of how it varies in time relative to temperature. Antarctic ice cores preserve highly resolved records of atmospheric CO2 and Antarctic temperature for the past 800,000 years. Here we propose a revised relative age scale for the concentration of atmospheric CO2 and Antarctic temperature for the last deglacial warming, using data from five Antarctic ice cores. We infer the phasing between CO2 concentration and Antarctic temperature at four times when their trends change abruptly. We find no significant asynchrony between them, indicating that Antarctic temperature did not begin to rise hundreds of years before the concentration of atmospheric CO2, as has been suggested by earlier studies.

Supplement to: Parrenin, Frédéric; Masson-Delmotte, Valerie; Köhler, Peter; Raynaud, Dominique; Paillard, Didier; Schwander, Jakob; Barbante, Carlo; Landais, Amaëlle; Wegner, Anna; Jouzel, Jean (2013): Synchronous change of atmospheric CO2 and Antarctic temperature during the last deglacial warming. Science, 339(6123), 1060-1063