Anthropogenic perturbation of the carbon fluxes from land to ocean
Mackenzie, Fred T.
Janssens, Ivan A.
Laruelle, Goulven G.
Andersson, Andreas J.
Borges, Alberto V.
Dale, Andrew W.
LaRowe, Douglas E.
Meysman, Filip J. R.
Raymond, Peter A.
Permanent link to this recordhttp://hdl.handle.net/10754/597586
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AbstractA substantial amount of the atmospheric carbon taken up on land through photosynthesis and chemical weathering is transported laterally along the aquatic continuum from upland terrestrial ecosystems to the ocean. So far, global carbon budget estimates have implicitly assumed that the transformation and lateral transport of carbon along this aquatic continuum has remained unchanged since pre-industrial times. A synthesis of published work reveals the magnitude of present-day lateral carbon fluxes from land to ocean, and the extent to which human activities have altered these fluxes. We show that anthropogenic perturbation may have increased the flux of carbon to inland waters by as much as 1.0 Pg C yr -1 since pre-industrial times, mainly owing to enhanced carbon export from soils. Most of this additional carbon input to upstream rivers is either emitted back to the atmosphere as carbon dioxide (∼0.4 Pg C yr -1) or sequestered in sediments (∼0.5 Pg C yr -1) along the continuum of freshwater bodies, estuaries and coastal waters, leaving only a perturbation carbon input of ∼0.1 Pg C yr -1 to the open ocean. According to our analysis, terrestrial ecosystems store ∼0.9 Pg C yr -1 at present, which is in agreement with results from forest inventories but significantly differs from the figure of 1.5 Pg C yr -1 previously estimated when ignoring changes in lateral carbon fluxes. We suggest that carbon fluxes along the land-ocean aquatic continuum need to be included in global carbon dioxide budgets.
CitationRegnier P, Friedlingstein P, Ciais P, Mackenzie FT, Gruber N, et al. (2013) Anthropogenic perturbation of the carbon fluxes from land to ocean. Nature Geosci 6: 597–607. Available: http://dx.doi.org/10.1038/NGEO1830.
SponsorsThis paper is the outcome of the workshop 'Exploring knowledge gaps along the global carbon route: a hitchhiker's guide for a boundless cycle' held in Eprave, Belgium, in November 2011. The authors would like to thank S. Bonneville, L. Chou, P. Cox, H. Durr, T. Eglinton, K. Fleischer, J. Kaplan, T. Kleinen, D. Dan Li, A. Mouchet, H. Nick, C. Pallud, C. Prentice, D. Schimel, M. Serrano, J-L. Tison, P. Van Cappellen, C. Volta and J. Zhou for their input during the workshop. The workshop was officially endorsed by the Global Carbon Project (GCP) and by the Analysis, Integration and Modeling of the Earth System (AIMES) of the International Geosphere-Biosphere Programme (IGBP) and received financial support from the government of the Brussels-Capital region (Innoviris - Brains Back to Brussels award to P. R.), the Walloon Agency for Air and Climate (AWAC), the Fonds National de la Recherche Scientifique of Belgium (FNRS), The Belgian Federal Science Policy Office (BELSPO), the Universite Libre de Bruxelles (Belgium), the Netherlands Organization for Scientific Research (NWO), the King Abdullah University of Science and Technology (KAUST) Center-in-Development Award to Utrecht University (The Netherlands), the University of Waterloo (Canada) and the University of Exeter (UK). The research leading to these results received funding from the European Union's Seventh Framework Program (FP7/2007-2013) under grant agreement number 283080, project GEOCARBON.