Climate Science

Wet and Dry Dating

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Science  02 Nov 2007:
Vol. 318, Issue 5851, pp. 717
DOI: 10.1126/science.318.5851.717d

A fundamental challenge in applying 14C dating to paleoceanography is that the radiocarbon age of sea surface water is different from that of the atmosphere above it, because of varying 14C production and distribution pathways. Knowing this difference (termed the marine radiocarbon reservoir age) in specific locations is essential for establishing comparative chronologies of changes in ocean circulation and climate between different regions, with the further aim of exploring the causal mechanisms. Sarnthein et al. have determined reservoir ages for four Pacific and Atlantic locations between 23,000 and 14,000 years before the present, using a radiocarbon plateau-tuning technique. The trends that they see require major changes in deep ocean circulation during different intervals of the record. Two major atmospheric 14C plateaus, during the end of the Heinrich 1 event and the early B¿lling interstadial, occur contemporaneously with the two-step early deglacial rise in atmospheric CO2 partial pressure and appear to reflect the transfer of CO2 from the deep ocean to the atmosphere. These results imply that 14C age calibration scales will need to be corrected accordingly. — HJS

Geophys. Monogr. Sci. 173 175 (2007).

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