Revised Estimates of Atmospheric CO2 Variations Based on the Tree-Ring 13C Record
Since the publication of a paper by Peng et al. (1983) regarding the analysis of the tree-ring-based δ13C record,* a number of reports giving new measurements of δ13C in tree rings have emerged (Leavitt and Long 1983; Stuiver et al. 1984; Freyer, this volume; Stuiver, this volume). The results of the original analysis were based on a global 13C/12C trend compiled by Freyer and Belacy (1983). Freyer (this volume) recalculated the 13C/12C trend of the Northern Hemisphere using measurements on 65 trees, including those presented in the publication of Leavitt and Long (1983), and he concluded that no long-term trend exists during the period of a few centuries before 1800 AD. By contrast, a clear trend of decreasing 13C was observed after 1800 AD. Freyer estimated the overall decrease of δ13C from 1800 to 1980 AD to be about −1.5‰, which is 0.5‰ less than that obtained from the composite 13C trend used by Peng et al. (1983). Therefore, a reevaluation of the terrestrial biosphere contribution to the lowering of δ13C in the atmospheric CO2 seems appropriate. This is the main objective of this chapter.
KeywordsFossil Fuel Tree Ring Terrestrial Biosphere Land Biosphere Ocean Carbon Cycle Model
Unable to display preview. Download preview PDF.
- Freyer, H. D. and N. Belacy. 1983. 13C/’ZC records in Northern Hemisphere trees during the past 500 years: anthropogenic impact and climatic superpositions. J. Geophys. Res. 88: 6844–6852.Google Scholar
- Friedli, H., E. Moor, H. Oeschger, U. Siegenthaler, and B. Stauffer. 1984. 13C/ ‘2C ratios in CO2 extracted from Antarctic ice. Geophys. Res. Lett. 11: 11451148.Google Scholar
- Houghton, R. A., J. E. Hobbie, J. M. Melillo, B. Moore, B. J. Peterson, G. R. Shaver, and G. M. Woodwell. 1983. Changes in the carbon content of terrestrial biota and soils between 1860 and 1980: a net release of CO2 to the atmosphere. Ecol. Monogr. 53: 235–262.Google Scholar
- Keeling, C. D., R. B. Bacastow, and P. Tans. 1980. Predicted shift in the 13C/12C ratio of atmospheric carbon dioxide. Geophys. Res. Lett. 7: 505–508.Google Scholar
- Keeling, C. D., R. B. Bacastow, and T. P. Whorf. 1982. Measurements of the concentration of carbon dioxide at Mauna Loa Observatory, Hawaii. In W. C. Clark (ed.), Carbon Dioxide Review: 1982, pp. 377–385. Oxford University Press, New York.Google Scholar
- Leavitt, S. W. and A. Long. 1983. An atmospheric 13C/12C reconstruction generated through removal of climatic effects from tree-ring 13C/’2C measurements. Tellus 35: 92–102.Google Scholar
- Peng, T.-H., W. S. Broecker, H. D. Freyer, and S. Trumbore. 1983. A decon- volution of the tree rings based 813C record. J. Geophys. Res. 88: 3609–3620.Google Scholar
- Schwarz, H. P. 1970. The stable isotopes of carbon. In K. H. Wedepohl (ed.), Handbook of Geochemistry, pp. 1–16. Springer-Verlag, New York.Google Scholar
- Stuiver, M., R. L. Burk, and P. D. Quay. 1984. 13C/’ZC ratios and the transfer of biospheric carbon to the atmosphere. J. Geophys. Res. 89: 11731–11748.Google Scholar
- Tans, P. 1981. 13C/’2C of industrial CO2. In B. Bolin (ed.), Carbon Cycle Modeling, SCOPE 16, pp. 127–129. John Wiley, New York.Google Scholar