Distinct roles of the Southern Ocean and North Atlantic in the deglacial atmospheric radiocarbon decline

Mathis P. Hain, Daniel Mikhail Sigman, Gerald H. Haug

Research output: Contribution to journalArticle

38 Scopus citations

Abstract

In the context of the atmospheric CO2 14C/C (δCatm14) changes since the last ice age, two episodes of sharp δCatm14 decline have been related to either the venting of deeply sequestered low-14C CO2 through the Southern Ocean surface or the abrupt onset of North Atlantic Deep Water (NADW) formation. In model simulations using an improved reconstruction of 14C production, Atlantic circulation change and Southern Ocean CO2 release both contribute to the overall deglacial δCatm14 decline, but only the onset of NADW can reproduce the sharp δCatm14 declines. To fully simulate δCatm14 data requires an additional process that immediately precedes the onsets of NADW. We hypothesize that these "early" δCatm14 declines record the thickening of the ocean's thermocline in response to reconstructed transient shutdown of NADW and/or changes in the southern hemisphere westerly winds. Such thermocline thickening may have played a role in triggering the NADW onsets.

Original languageEnglish (US)
Pages (from-to)198-208
Number of pages11
JournalEarth and Planetary Science Letters
Volume394
DOIs
StatePublished - May 15 2014

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Geochemistry and Petrology
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

Keywords

  • AMOC
  • Carbon cycle
  • Deglaciation
  • Ice age
  • Ocean circulation
  • Radiocarbon

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