Document Type

Article

Publication Title

Journal of Geophysical Research—Oceans

Publisher

American Geophysical Union

Publication Date

11-30-1997

First Page

26,577

Last Page

26,582

Issue Number

C12

Volume Number

102

Abstract/ Summary

The CO2 content of air occluded in Greenland Ice Sheet Project 2 (GISP2) ice formed over two separate intervals of rapidly changing climate, centered at approximately 46 and 63 kyr B. P., is as much as 90 ppm more during warm periods (interstadials) than during cold periods (stadials). These CO2 variations are superimposed on changes in annual layer thickness and δ18O of the ice and do not show the 200- to 700-year offsets which would be expected for concurrent variations in the atmosphere and the ice. The CO2 concentrations during the stadials are similar to the atmospheric values recorded by Antarctic ice of the same age, so processes occurring in the ice after bubble enclosure must be enriching the air trapped in GISP2 ice formed during the interstadials. This conclusion is supported by Ca content and electrical conductivity measurements of the ice, which show that adequate carbonate is present to produce these enrichments and that CO2 content is high only when the electrical conductivity (a proxy for H+ concentration) is high. High-resolution mapping of one 4-cm section of ice shows a 200-ppm increase in the CO2 content of the trapped air, from approximately 275 to 475 ppm. Analyses of the total inorganic carbon of ice from both the LGM and Holocene show that most of the Ca in the ice is from CaCO3 and that the δ13CO2 approaches that of soil and marine carbonates. These results show that the CO2 record preserved in ice can be altered by in situ decarbonation reactions and that only ice containing either abundant carbonate or essentially no carbonate contains a reliable record of paleoatmospheric CO2.

Citation/Publisher Attribution

Smith, H. J., M. Wahlen, D. Mastroianni, K. Taylor, and P. Mayewski (1997), The CO2 concentration of air trapped in Greenland Ice Sheet Project 2 ice formed during periods of rapid climate change, Journal of Geophysical Research, 102(C12), 26,577–26,582, doi:10.1029/97JC00163.

Publisher Statement

© Copyright 1997 by the American Geophysical Union

DOI

10.1029/97JC00163

Version

publisher's version of the published document

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