A synthesis of deglacial deep‐sea radiocarbon records and their (in)consistency with modern ocean ventilation
Keigwin, Lloyd D.
Amrhein, Daniel E.
Gebbie, Geoffrey A.
MetadataShow full item record
We present a synthesis of 1,361 deep‐sea radiocarbon data spanning the past 40 kyr and computed (for 14C‐dated records) from the same calibration to atmospheric 14C. The most notable feature in our compilation is a long‐term Δ14C decline in deep oceanic basins over the past 25 kyr. The Δ14C decline mirrors the drop in reconstructed atmospheric Δ14C, suggesting that it may reflect a decrease in global 14C inventory rather than a redistribution of 14C among different reservoirs. Motivated by this observation, we explore the extent to which the deep water Δ14C data jointly require changes in basin‐scale ventilation during the last deglaciation, based on the fit of a 16‐box model of modern ocean ventilation to the deep water Δ14C records. We find that the fit residuals can largely be explained by data uncertainties and that the surface water Δ14C values producing the fit are within the bounds provided by contemporaneous values of atmospheric and deep water Δ14C. On the other hand, some of the surface Δ14C values in the northern North Atlantic and the Southern Ocean deviate from the values expected from atmospheric 14CO2 and CO2 concentrations during the Heinrich Stadial 1 and the Bølling‐Allerød. The possibility that deep water Δ14C records reflect some combination of changes in deep circulation and surface water reservoir ages cannot be ruled out and will need to be investigated with a more complete model.
Author Posting. © American Geophysical Union, 2018. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Paleoceanography and Paleoclimatology 33 (2018): 128-151, doi:10.1002/2017PA003174.
Suggested CitationPaleoceanography and Paleoclimatology 33 (2018): 128-151
Showing items related by title, author, creator and subject.
Zhao, Ning (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2017-02)Significant changes occurred during the last deglaciation (roughly 10-20 thousand years (ka) before present) throughout the climate system. The ocean is a large reservoir of carbon and heat, however, its role during the ...
Radiocarbon profiles of the NW Pacific from the LGM and deglaciation : evaluating ventilation metrics and the effect of uncertain surface reservoir ages Cook, Mea S.; Keigwin, Lloyd D. (John Wiley & Sons, 2015-03-12)During the last deglaciation, the ventilation of the subarctic Pacific is hypothesized to have changed dramatically, including the rejuvenation of a poorly ventilated abyssal water mass that filled the deep ocean, and ...
Radiocarbon and stable isotope constraints on Last Glacial Maximum and Younger Dryas ventilation in the western North Atlantic Keigwin, Lloyd D. (American Geophysical Union, 2004-11-03)Foraminiferal abundance, 14C ventilation ages, and stable isotope ratios in cores from high deposition rate locations in the western subtropical North Atlantic are used to infer changes in ocean and climate during the ...