Glacial – interglacial atmospheric CO2 change: a simple "hypsometric effect" on deep-ocean carbon sequestration?

Article, Other literature type English OPEN
Skinner, L. C.

Given the magnitude and dynamism of the deep marine carbon reservoir, it is almost certain that past glacial &ndash; interglacial fluctuations in atmospheric CO<sub>2</sub> 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 &ndash; interglacial CO<sub>2</sub> 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 CO<sub>2</sub> 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 &ndash; interglacial CO<sub>2</sub> 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 CO<sub>2</sub> 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 &ndash; interglacial CO<sub>2</sub> change.
  • References (63)
    63 references, page 1 of 7

    Archer, D., Eshel, G., Winguth, A., Broecker, W. S., Pierrehumbert, R., Tobis, M., and Jacob, R.: Atmospheric pCO2 sensitivity to the bioloical pump in the ocean, Global Biochem. Cycles, 14, 1219-1230, 2000a.

    Archer, D. and Maier-Reimer, E.: E ffect of deep-sea sedimentary calcite preservation on atmospheric CO2 concentration, Nature, 367, 260-263, 1994.

    Archer, D., Winguth, A., Lea, D. W., and Mahowald, N.: What caused the glacial/interglacial atmospheric pCO2 cycles?, Rev. Geophys., 38, 159-189, 2000b.

    Bard, E.: Correction of accelerator mass spectrometry 14C ages measured in planktonic foraminifera: Paleoceanographic implications, Paleoceanography, 3, 635-645, 1988.

    Boyle, E.: Cadmium and d13C paleochemical ocean distributions during the Stage 2 glacial maximum, Ann. Rev. Earth Planet. Sci., 20, 245-287, 1992.

    Boyle, E. A.: The role of vertical fractionation in controlling late Quaternary atmospheric carbon dioxide, J. Geophys. Res., 93, 15 701-15 714, 1988.

    5 Brix, H. and Gerdes, R.: North Atlantic Deep Water and Antarctic Bottom Water: Their interaction and influence on the variability of the global ocean circulation, J. Geophys. Res., 108(C2), doi:10.1029-2002JC0021335, 2003.

    Broecker, W.: How strong is the Harvardton-Bear constraint?, Global Biogeochem. Cycles, 13, 817-820, 1999.

    10 Broecker, W. S.: Glacial to interglacial changes in ocean chemistry, Progress in Oceanography, 11, 151-197, 1982a.

    Broecker, W. S.: Ocean chemistry during glacial time, Geochim. Cosomochim. Acta, 46, 1698- 1705, 1982b.

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