Glacial to Interglacial Changes in Atmospheric Carbon Dioxide: The Critical Role of Ocean Surface Water in High Latitudes

  1. E.T. Sundquist and
  2. W.S. Broecker
  1. J. R. Toggweiler and
  2. J. L. Sarmiento

Published Online: 18 MAR 2013

DOI: 10.1029/GM032p0163

The Carbon Cycle and Atmospheric CO: Natural Variations Archean to Present

The Carbon Cycle and Atmospheric CO: Natural Variations Archean to Present

How to Cite

Toggweiler, J. R. and Sarmiento, J. L. (1985) Glacial to Interglacial Changes in Atmospheric Carbon Dioxide: The Critical Role of Ocean Surface Water in High Latitudes, in The Carbon Cycle and Atmospheric CO: Natural Variations Archean to Present (eds E.T. Sundquist and W.S. Broecker), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM032p0163

Author Information

  1. Geophysical Fluid Dynamics Program, Princeton University, Princeton, New Jersey 08542

Publication History

  1. Published Online: 18 MAR 2013
  2. Published Print: 1 JAN 1985

ISBN Information

Print ISBN: 9780875900605

Online ISBN: 9781118664322

SEARCH

Keywords:

  • Carbon cycle (Biogeochemistry)—Congresses;
  • Atmospheric carbon dioxide—Congresses;
  • Geological time—Congresses;
  • Paleothermometry—Congresses;
  • Geology, Stratigraphic—Congresses

Summary

Recent measurements of the CO2 content of air bubbles trapped in glacial ice have shown that the partial pressure of atmospheric CO2 during the last ice age was about 70 ppm lower than during the interglacial. Isotopic measurements on surface- and bottom-dwelling forams living during the ice age have shown that the 13C/12C gradient between the ocean's surface and bottom layers was 25% larger during the last ice age than at present. Broecker (1982) proposed that an increase in the phosphate content of the deep sea could explain these observations. We follow up here on a proposal by Sarmiento and Toggweiler (1984) that glacial to interglacial changes in PCO 2 are related to changes in the nutrient content of high-latitude surface water. We develop a four-box model of the ocean and atmosphere which includes low- and high-latitude surface boxes, an atmosphere, and a deep ocean. In simplest form the model equations show that the CO2 content of high-latitude surface water is directly connected to the huge reservoir of CO2 in deep water through the nutrient content of high-latitude surface water. The relationship between the CO2 content of low latitude surface water and the deep sea is more indirect and depends to a large extent on transport of CO2 through the atmosphere from high latitudes. We illustrate how the 14C content of the atmosphere and that of high-latitude surface water constrain model solutions for the present ocean and how ice age 13C observations constrain ice age parameters. We propose that the low ice age PCO 2 can be produced by a reduction in local exchange between high-latitude surface water and deep water. The model requires that the current exchange rate of about 50 Sv be reduced to about 10 Sv. We review evidence in the geologic record for widespread changes in deep convection around Antarctica about 14,000 years ago which are synchronous with the change in atmospheric PCO 2.