Atmospheric CO2 Concentration During the Last Glaciation

Abstract

Analyses of atmospheric air extracted from air bubbles in polar glacier ice provide a measure of past CO2 concentrations and their temporal variations. Earlier measurements have shown that the atmospheric CO2 concentration was significantly lower during the late Wisconsin stage and that the change from low to high CO2 concentration occurred in a relatively short time period.We measured the CO2 concentration of ice samples from the deep ice core recently drilled at Dye 3 (south Greenland). The core section investigated represents ice from about 40 to 30 ka BP. The air extracted from the ice samples shows large variations of CO2 concentration which are correlated with δ18O values of the ice samples. A probable explanation of the results is that corresponding changes of the atmospheric CO2 concentration occurred during that glacial period. These changes could have had a significant influence on the climate. Possible reasons for the variations of the atmospheric CO2 concentration are discussed.