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Climate and interannual variability of the atmosphere-biosphere 13CO2 flux

  • M. Scholze
  • J. O. Kaplan
  • W. Knorr
  • M. Heimann
Publishing year: 2003-01-15
Language: English
Publication/Series: Geophysical Research Letters
Volume: 30
Issue: 2
Document type: Journal article
Publisher: American Geophysical Union (AGU)

Abstract english

We present a bottom-up approach to simulate the terrestriál isotopic carbon variations using the Lund-Postsdam-Jena dynamic global vegetation model (LPJ-DGVM). LPJ is extended to include isotopic fractionation of 13C at the leaf level during assimilation and includes a full isotopic terrestrial carbon cycle. The model thus allows a quantitative analysis of the net biosphere exchange of CO2 and 13CO2 with the atmosphere as a function of changes in climate, atmospheric CO2, and the isotope ratio of CO2. LPJ simulates a global mean isotopic fractionation of 17.7‰ at the leaf level with interannual variations of ca. 0.3‰. Interannual variability in the net 13CO2 flux between atmosphere and terrestrial biosphere is of the order of 15 PgC‰ yr-1. It is reduced to 4 PgC‰ yr-1 if the leaf-level fractionation factor is held constant at the long term mean. Taking climate driven variable fractionation effects into account in double deconvolution studies we estimate that this could imply shifts of up to 0.8 PgC yr-1 in the inferred partitioning between terrestrial and oceanic carbon sinks.


  • Climate Research


  • ISSN: 0094-8276
E-mail: wolfgang [dot] knorr [at] nateko [dot] lu [dot] se

Department of Physical Geography and Ecosystem Science
Lund University
Sölvegatan 12
S-223 62 Lund

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