CO2-climate relationship as deduced from the Vostok ice core: a re- examination based on new measurements and on a re-evaluation of the air dating

Abstract

Interpretation of the past CO2 variations recorded in polar ice during the large climatic transitions requires an accurate determination of the air-ice age difference. For the Vostok core, the age differences resulting from different assumptions on the firn densification process are compared and a new procedure is proposed to date the air trapped in this core. The penultimate deglaciation is studied on the basis of this new air dating and new CO2 measurements. These measurements and results obtained on other ice cores indicate that at the beginning of the deglaciations, the CO2 increase is either in phase or lags by less than about 1000 years with respect to the Antarctic temperature, while it clearly lags the temperature at the onset of the last glaciation. -Authors