Variations of the CO2 concentration of occluded air and of anions and dust in polar ice cores

• Main Authors: Oeschger, H., Stauffer, B., Finkel, R., Langway Jr., C.C.
• Other Authors: Sundquist, E.T., Broecker, W.S.
• Format: Book Part
• Language: English
• Published: American Geophysical Union 1985
• Subjects: 530 Physics; Antarctic; Greenland; The Antarctic; Antarc*; Dye 3; Dye-3; ice core
• Online Access: https://boris.unibe.ch/160973/1/Oeschger_Variations_of_the_CO2_concentration_of_occluded_air.pdf; https://boris.unibe.ch/160973/

Analysis of impurities entrapped in natural ice is the most promising method for reconstructing the history of atmospheric composition before the period of direct measurement and offers the possibility of extending the record to at least 100,000 years B.P. We report here the present state of work in this field, with special emphasis on atmospheric CO2 concentration. After discussing the mechanism by which atmospheric gases are entrapped in ice, we report CO2 concentrations in ice core samples, up to 100,000 years old, from deep drilling projects in Greenland and the Antarctic. Results from ice deposited during the last 2000 years allow us to estimate the preindustrial atmospheric CO2 level, an important boundary condition for modelling the anthropogenic CO2 increase. Using older samples from a deep ice core drilled at Dye 3, Greenland, we show that the CO2 concentration was 180 to 200 ppmv at the end of the Wisconsin and increased during the transition to the Holocene to values in the 260 to 300 ppmv range. Detailed CO2 measurements on sections of the Wisconsin part of the Dye 3 core which, based on δ18O, were deposited during times of significant climatic variation, show that the δ18O variations were accompanied by simultaneous correlated rapid CO2 variations. Other parameters, including micro-particle concentration and Cl−, NO− 3 and SO2− 4 concentrations also showed significant variations which correlate with the measured δ18O shifts.