Global increase in plant carbon isotope fractionation following the last glacial maximum caused by increase in atmospheric pCO2

Changes in the carbon isotope composition of terrestrial plant tissue (δ13C) are widely cited for evidence of shifts in climate, vegetation, or atmospheric chemistry across a wide range of time scales. A global compilation of δ13C data from fossil leaves and bulk terrestrial organic matter (TOM) spa...

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Bibliographic Details
Published in:Geology (Boulder) 2015-03, Vol.43 (5), p.435-438
Main Authors: Schubert, Brian A, Jahren, A. Hope
Format: Article
Language:English
Subjects:
C-13/C-12
carbon
carbon dioxide
Cenozoic
geochemistry
global
isotope fractionation
isotope ratios
isotopes
leaves
paleoatmosphere
paleoenvironment
Quaternary
Quaternary geology
stable isotopes
upper Quaternary
vegetation
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Summary:Changes in the carbon isotope composition of terrestrial plant tissue (δ13C) are widely cited for evidence of shifts in climate, vegetation, or atmospheric chemistry across a wide range of time scales. A global compilation of δ13C data from fossil leaves and bulk terrestrial organic matter (TOM) spanning the past 30 k.y., however, shows wide variability and no discernable trend. Here we analyze these data in terms of a relative change in net carbon isotope fractionation between the δ13C value of plant tissue and that of atmospheric CO2 [Δ13C = (δ13CCO2 - δ13C)/(1 + δ13C/1000)] and identify a global 2.1 ppm shift in leaf and TOM Δ13C that is synchronous with a global rise in pCO2 documented from ice core data. We apply a relationship describing the effect of pCO2 on Δ13C to the global record of Δ13C change documented here to reconstruct pCO2 levels across the past 30 k.y. Our reconstructed pCO2 levels are in excellent agreement with the ice core data and underscore the potential of the global terrestrial δ13C record to serve as an accurate pCO2 proxy.
ISSN:0091-7613
1943-2682
DOI:10.1130/G36467.1