Title: Global covariation of carbon turnover times with climate in terrestrial ecosystems
Authors: CARVALHAIS NunoFORKEL MatthiasKHOMIK MyroslavaBELLARBY JessicaJUNG MartinMIGLIAVACCA MircoMU MingquanSAATCHI SassanSANTORO MaurizioTHURNER MartinWEBER UlrichAHRENS BernhardBEER C.CESCATTI AlessandroRANDERSON James T.REICHSTEIN Markus
Citation: NATURE vol. 514 no. 7521 p. 213-217
Publisher: NATURE PUBLISHING GROUP
Publication Year: 2014
JRC N°: JRC91107
ISSN: 0028-0836
URI: http://www.nature.com/nature/journal/v514/n7521/full/nature13731.html
http://publications.jrc.ec.europa.eu/repository/handle/JRC91107
DOI: 10.1038/nature13731
Type: Articles in periodicals and books
Abstract: The response of the terrestrial carbon cycle to climatic change is among the largest uncertainties affecting future climate change projections1,2. The feedback between the terrestrial carbon cycle and climate is partly determined by changes in the residence time of carbon in land ecosystems, which in turn is an ecosystem property that emerges from the interplay between climate, soil, and vegetation type3,4,5,6. Here, we present a global, spatially explicit and observation-based assessment of whole-ecosystem carbon turnover times (τ) that combines new estimates of vegetation and soil organic carbon stocks and fluxes. We find that the overall mean global carbon turnover time is years (95% CI). On average, carbon resides in the vegetation and soil near the equator for a shorter time period than at latitudes north of 75ºN (mean τ of 15 and 255 years, respectively). We identify clear dependencies of τ on temperature, as expected based on our current understanding of temperature controls on ecosystem dynamics. Surprisingly, our analysis also reveals similarly strong associations of τ with precipitation. Moreover, we find that the ecosystem carbon turnover times simulated by state-of-the-art coupled climate carbon-cycle models vary widely and that numerical simulations, on average, tend to underestimate the global carbon turnover time by 36 per cent. The models show stronger spatial relationships with temperature than observation-based estimates, but generally do not reproduce the strong relationships with precipitation and predict faster carbon turnover in many semi-arid regions. Our findings suggest that future carbon cycle-climate feedbacks may depend more strongly on changes in the hydrological cycle than currently expected and considered in Earth system models.
JRC Directorate:Sustainable Resources

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