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Stomatal evidence for a decline in atmospheric CO 2 concentration during the Younger Dryas stadial: a comparison with Antarctic ice core records

2002; Wiley; Volume: 17; Issue: 1 Linguagem: Inglês

10.1002/jqs.664

1099-1417

Jennifer C. McElwain, Francis E. Mayle, David J. Beerling,

Paleontology and Stratigraphy of Fossils

Abstract A recent high‐resolution record of Late‐glacial CO 2 change from Dome Concordia in Antarctica reveals a trend of increasing CO 2 across the Younger Dryas stadial (GS‐1). These results are in good agreement with previous Antarctic ice‐core records. However, they contrast markedly with a proxy CO 2 record based on the stomatal approach to CO 2 reconstruction, which records a ca. 70 ppm mean CO 2 decline at the onset of GS‐1. To address these apparent discrepancies we tested the validity of the stomatal‐based CO 2 reconstructions from Kråkenes by obtaining further proxy CO 2 records based on a similar approach using fossil leaves from two independent lakes in Atlantic Canada. Our Late‐glacial CO 2 reconstructions reveal an abrupt ca. 77 ppm decrease in atmospheric CO 2 at the onset of the Younger Dryas stadial, which lagged climatic cooling by ca. 130 yr. Furthermore, the trends recorded in the most accurate high‐resolution ice‐core record of CO 2 , from Dome Concordia, can be reproduced from our stomatal‐based CO 2 records, when time‐averaged by the mean age distribution of air contained within Dome Concordia ice (200 to 550 yr). If correct, our results indicate an abrupt drawdown of atmospheric CO 2 within two centuries at the onset of GS‐1, suggesting that some re‐evaluation of the behaviour of atmospheric CO 2 sinks and sources during times of rapid climatic change, such as the Late‐glacial, may be required. Copyright © 2002 John Wiley & Sons, Ltd.