Articles | Volume 4, issue 2
Clim. Past, 4, 125–136, 2008
https://doi.org/10.5194/cp-4-125-2008
Clim. Past, 4, 125–136, 2008
https://doi.org/10.5194/cp-4-125-2008

  25 Jun 2008

25 Jun 2008

Modeling variations of marine reservoir ages during the last 45 000 years

J. Franke1, A. Paul2,1, and M. Schulz2,1 J. Franke et al.
  • 1Department of Geosciences, University of Bremen, Germany
  • 2MARUM – Center for Marine Environmental Sciences, University of Bremen, Germany

Abstract. When dating marine samples with 14C, the reservoir-age effect is usually assumed to be constant, although atmospheric 14C production rate and ocean circulation changes cause temporal and spatial reservoir-age variations. These lead to dating errors, which can limit the interpretation of cause and effect in paleoclimate data. We used a global ocean circulation model forced by transient atmospheric Δ14C variations to calculate reservoir ages for the last 45 000 years for a present day-like and a last glacial maximum-like ocean circulation. A ~30% reduced Atlantic meridonal overturning circulation leads to increased reservoir ages by up to ~500 years in high latitudes. Temporal variations are proportional to the absolute value of the reservoir age; regions with large reservoir age also show large variation. Temporal variations range between ~300 years in parts of the subtropics and ~1000 years in the Southern Ocean. For tropical regions, which are generally assumed to have nearly stable reservoir ages, the model suggests variations of several hundred years.

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