Oceanic sources, sinks, and transport of atmospheric CO2
| Type | Article | ||||||||
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| Date | 2009-02 | ||||||||
| Language | English | ||||||||
| Author(s) | Gruber Nicolas1, Gloor Manuel2, 3, Fletcher Mikaloff Sara E.4, Doney Scott C.5, Dutkiewicz Stephanie6, Follows Michael J.6, Gerber Markus7, Jacobson Andrew R.8, Joos Fortunat7, 9, Lindsay Keith10, Menemenlis Dimitris11, Mouchet Anne12, Mueller Simon A.7, Sarmiento Jorge L.3, Takahashi Taro13 | ||||||||
| Affiliation(s) | 1 : Environmental Physics, Institute of Biogeochemistry and Pollutant Dynamics, ETH Zürich, Zürich, Switzerland 2 : nstitutes of Earth and Biosphere and Earth, Energy and Environment, University of Leeds, Leeds, UK 3 : School of Geography, University of Leeds, Leeds, UK 4 : Program in Atmospheric and Oceanic Sciences, Princeton University, Princeton, New Jersey, USA 5 : Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA 6 : Department of Earth, Atmosphere, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA 7 : Climate and Environmental Physics, Physics Institute, University of Bern, Bern, Switzerland 8 : NOAA Earth System Research Laboratory, Global Monitoring Division, Boulder, Colorado, USA 9 : Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland 10 : Climate and Global Dynamics, National Center for Atmospheric Research, Boulder, Colorado, USA 11 : Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA 12 : Astrophysics and Geophysics Institute, University of Liege, Liege, Belgium 13 : Lamont-Doherty Earth Observatory of Columbia University, Palisades, New York, USA |
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| Source | Global Biogeochemical Cycles (0886-6236) (Amer Geophysical Union), 2009-02 , Vol. 23 , N. 1/GB1005 , P. 1-21 | ||||||||
| DOI | 10.1029/2008GB003349 | ||||||||
| WOS© Times Cited | 365 | ||||||||
| Keyword(s) | air-sea carbon flux, carbon flux, anthropogenic CO2 | ||||||||
| Abstract | We synthesize estimates of the contemporary net air-sea CO2 flux on the basis of an inversion of interior ocean carbon observations using a suite of 10 ocean general circulation models (Mikaloff Fletcher et al., 2006, 2007) and compare them to estimates based on a new climatology of the air-sea difference of the partial pressure of CO2 (pCO(2)) (Takahashi et al., 2008). These two independent flux estimates reveal a consistent description of the regional distribution of annual mean sources and sinks of atmospheric CO2 for the decade of the 1990s and the early 2000s with differences at the regional level of generally less than 0.1 Pg C a(-1). This distribution is characterized by outgassing in the tropics, uptake in midlatitudes, and comparatively small fluxes in the high latitudes. Both estimates point toward a small(similar to -0.3 Pg C a(-1)) contemporary CO2 sink in the Southern Ocean (south of 44 degrees S), a result of the near cancellation between a substantial outgassing of natural CO2 and a strong uptake of anthropogenic CO2. A notable exception in the generally good agreement between the two estimates exists within the Southern Ocean: the ocean inversion suggests a relatively uniform uptake, while the pCO(2)-based estimate suggests strong uptake in the region between 58 degrees S and 44 degrees S, and a source in the region south of 58 degrees S. Globally and for a nominal period between 1995 and 2000, the contemporary net air-sea flux of CO2 is estimated to be -1.7 +/- 0.4 Pg C a(-1) (inversion) and -1.4 +/- 0.7 Pg C a(-1) (pCO(2)-climatology), respectively, consisting of an outgassing flux of river-derived carbon of similar to+0.5 Pg C a(-1), and an uptake flux of anthropogenic carbon of -2.2 +/- 0.3 Pg C a(-1) (inversion) and -1.9 +/- 0.7 Pg C a(-1) (pCO(2)-climatology). The two flux estimates also imply a consistent description of the contemporary meridional transport of carbon with southward ocean transport throughout most of the Atlantic basin, and strong equatorward convergence in the Indo-Pacific basins. Both transport estimates suggest a small hemispheric asymmetry with a southward transport of between -0.2 and -0.3 Pg C a(-1) across the equator. While the convergence of these two independent estimates is encouraging and suggests that it is now possible to provide relatively tight constraints for the net air-sea CO2 fluxes at the regional basis, both studies are limited by their lack of consideration of long-term changes in the ocean carbon cycle, such as the recent possible stalling in the expected growth of the Southern Ocean carbon sink. | ||||||||
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