Changes in Atmospheric CO2: Factors Regulating the Glacial to Interglacial Transition

  1. E.T. Sundquist and
  2. W.S. Broecker
  1. Fanny Knox Ennever and
  2. Michael B. Mcelroy

Published Online: 18 MAR 2013

DOI: 10.1029/GM032p0154

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

Ennever, F. K. and Mcelroy, M. B. (2013) Changes in Atmospheric CO2: Factors Regulating the Glacial to Interglacial Transition, 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/GM032p0154

Author Information

  1. Center for Earth and Planetary Physics, Harvard University, Cambridge, Massachusetts 02138

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

An acceptable model for the glacial ocean must be consistent with available data for δ13C in both deep and shallow waters, and must account also for recent observations indicating that the level of atmospheric CO2 was lower during glacial times than in the preindustrial interglacial environment by about 100 ppm. Glacial deep-sea carbon was isotopically light compared to present, suggesting that the glacial to interglacial transition was accompanied by transfer of about 5×1016 moles of carbon from the ocean to an organic reservoir, most probably a combination of the terrestrial biosphere and coastal sediments. The associated change in pCO2 was investigated using a five-box model for the ocean-atmosphere system and was found to be insufficient on its own to account for the ice core data. It is argued that the low values for glacial pCO2 require higher deep-sea nutrient concentrations and/or lower levels of preformed nutrients. Reduction in preformed nutrient concentrations could reflect a change in the supply of water to zones of downwelling, specifically a larger relative contribution in glacial times due to advection of surface waters from lower latitude, or an increased efficiency for biological utilization of nutrients at high latitude, or both.