Atmospheric CO2 Variations Based on the Tree-Ring 13C Record

  1. E.T. Sundquist and
  2. W.S. Broecker
  1. T.-H. Peng

Published Online: 18 MAR 2013

DOI: 10.1029/GM032p0123

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

Peng, T.-H. (1985) Atmospheric CO2 Variations Based on the Tree-Ring 13C Record, 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/GM032p0123

Author Information

  1. Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831

Publication History

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

ISBN Information

Print ISBN: 9780875900605

Online ISBN: 9781118664322

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Keywords:

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

Summary

The reconstruction of atmospheric CO2 concentrations over the last 150 years, based on a deconvolution of the tree-ring-based 13C record, is reviewed. Assuming that Freyer's latest composite 13C record for the northern hemisphere represents global changes in the 13C/12C ratio of atmospheric CO2 induced by changes in atmospheric CO2 concentration due to deforestation, soil manipulation, and combustion of fossil fuels, the deconvolution, using the modified box-diffusion model, gives the following results: (1) the magnitude of the integrated CO2 release from the terrestrial biosphere since 1800 is about 90% of that from fossil fuel; (2) over the two-decade period covered by the Mauna Loa atmospheric CO2 record, the input from the forest-soil source is about 15% of that from fossil fuels; (3) the 13C/12C trend and the atmospheric CO2 anomaly over the last two decades have been dominated by the input of fossil fuel CO2; and (4) the pre-1850 atmospheric CO2 content is estimated to be about 266 ppm. The integrated amount of CO2 released from the terrestrial biosphere between A.D. 1800 and 1980 is estimated to be 12×1015 mol which is to be compared with the previous estimate of 22×1015 mol on the basis of Freyer and Belacy's (1983) 13C data. This indicates that tree-ring 13C-based estimates are volatile and further changes are likely.