Journal cover Journal topic
Climate of the Past An interactive open-access journal of the European Geosciences Union
© Author(s) 2006. This work is licensed under
the Creative Commons Attribution-NonCommercial-ShareAlike 2.5 License.
07 Sep 2006
Review status
This discussion paper is a preprint. It has been under review for the journal Climate of the Past (CP). A final paper in CP is not foreseen.
Glacial – interglacial atmospheric CO2 change: a simple "hypsometric effect" on deep-ocean carbon sequestration?
L. C. Skinner Godwin Laboratory for Palaeoclimate Research, Department of Earth Sciences, University of Cambridge, CB2 3EQ, UK
Abstract. Given the magnitude and dynamism of the deep marine carbon reservoir, it is almost certain that past glacial – interglacial fluctuations in atmospheric CO2 have relied at least in part on changes in the carbon storage capacity of the deep sea. To date, physical ocean circulation mechanisms that have been proposed as viable explanations for glacial – interglacial CO2 change have focussed almost exclusively on dynamical or kinetic processes. Here, a simple mechanism is proposed for increasing the carbon storage capacity of the deep sea that operates via changes in the volume of southern-sourced deep-water filling the ocean basins, as dictated by the hypsometry of the ocean floor. It is proposed that a water-mass that occupies more than the bottom 3 km of the ocean will essentially determine the carbon content of the marine reservoir. Hence by filling this interval with southern-sourced deep-water (enriched in dissolved CO2 due to its particular mode of formation) the amount of carbon sequestered in the deep sea may be greatly increased. A simple box-model is used to test this hypothesis, and to investigate its implications. It is suggested that up to 70% of the observed glacial – interglacial CO2 change might be explained by the replacement of northern-sourced deep-water below 2.5 km water depth by its southern counterpart. Most importantly, it is found that an increase in the volume of southern-sourced deep-water allows glacial CO2 levels to be simulated easily with only modest changes in Southern Ocean biological export or overturning. If incorporated into the list of contributing factors to marine carbon sequestration, this mechanism may help to significantly reduce the "deficit" of explained glacial – interglacial CO2 change.

Citation: Skinner, L. C.: Glacial – interglacial atmospheric CO2 change: a simple "hypsometric effect" on deep-ocean carbon sequestration?, Clim. Past Discuss., 2, 711-743,, 2006.
L. C. Skinner
Interactive discussionStatus: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version      Supplement - Supplement
RC S480: 'Glacial-interglacial atmospheic CO2', Anonymous Referee #2, 18 Oct 2006 Printer-friendly Version 
RC S499: 'Anonymous Referee 1', Anonymous Referee #1, 25 Oct 2006 Printer-friendly Version 
AC S647: 'Response to referees 1 and 2', Luke Skinner, 28 Nov 2006 Printer-friendly Version 
L. C. Skinner
L. C. Skinner


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