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

Summary, in 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.

• Författare: M. Scholze; J. O. Kaplan; W. Knorr; M. Heimann
• Publiceringsår: 2003-01-15
• Språk: Engelska
• Publikation/Tidskrift/Serie: Geophysical Research Letters
• Volym: 30
• Issue: 2
• Länkar: http://dx.doi.org/10.1029/2002GL015631
• Dokumenttyp: Artikel i tidskrift
• Förlag: American Geophysical Union (AGU)
• Ämne: Climate Research
• Status: Published
• ISBN/ISSN/Övrigt: ISSN: 0094-8276