Biogeosciences, 10, 1983-2000, 2013
© Author(s) 2013. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
22 Mar 2013
Global ocean carbon uptake: magnitude, variability and trends
R. Wanninkhof1, G. -H. Park1,2,*, T. Takahashi3, C. Sweeney4,16, R. Feely5, Y. Nojiri6, N. Gruber7, S. C. Doney8, G. A. McKinley9, A. Lenton10, C. Le Quéré11, C. Heinze12,13,14, J. Schwinger12,13, H. Graven7,15, and S. Khatiwala3 1Ocean Chemistry Division, NOAA/AOML, 4301 Rickenbacker Causeway, Miami, FL 33149, USA
2Cooperative Institute for Marine and Atmospheric Studies, University of Miami, Miami, FL 33149, USA
3Lamont-Doherty Earth Observatory of Columbia University, Route 9W, Palisades, NY 10964, USA
4NOAA/ESRL Carbon Cycle Group Aircraft Project Lead, 325 Broadway GMD/1, Boulder, CO 80304, USA
5Ocean Climate Research Division, NOAA/PMEL, 7600 Sand Point Way NE, Seattle, WA 98115, USA
6Center for Global Environmental Research National Institute for Environmental Studies Onogawa 16-2, Tsukuba, Ibaraki 305-8506, Japan
7Environmental Physics Group, Institute of Biogeochemistry and Pollutant Dynamics, ETH Zurich, 8092 Zurich, Switzerland
8Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
9Atmospheric and Oceanic Sciences and Center for Climatic Research, University of Wisconsin – Madison, WI 53706, USA
10CSIRO Marine and Atmospheric Research, P.O. BOX 1538 Hobart Tasmania, Australia
11Tyndall Centre for Climate Change Research, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
12Geophysical Institute, University of Bergen, Allegaten 70, 5007 Bergen, Norway
13Bjerknes Centre for Climate Research, Bergen, Norway
14Uni Bjerknes Centre, Uni Research, Bergen, Norway
15Scripps Institution of Oceanography, University of California San Diego, 9500 Gilman Dr., La Jolla, CA 92093, USA
16CIRES, University of Colorado, Boulder, CO 80304, USA
*now at: East Sea Research Institute, Korea Institute of Ocean Science & Technology, Uljin, 767–813, Korea
Abstract. The globally integrated sea–air anthropogenic carbon dioxide (CO2) flux from 1990 to 2009 is determined from models and data-based approaches as part of the Regional Carbon Cycle Assessment and Processes (RECCAP) project. Numerical methods include ocean inverse models, atmospheric inverse models, and ocean general circulation models with parameterized biogeochemistry (OBGCMs). The median value of different approaches shows good agreement in average uptake. The best estimate of anthropogenic CO2 uptake for the time period based on a compilation of approaches is −2.0 Pg C yr−1. The interannual variability in the sea–air flux is largely driven by large-scale climate re-organizations and is estimated at 0.2 Pg C yr−1 for the two decades with some systematic differences between approaches. The largest differences between approaches are seen in the decadal trends. The trends range from −0.13 (Pg C yr−1) decade−1 to −0.50 (Pg C yr−1) decade−1 for the two decades under investigation. The OBGCMs and the data-based sea–air CO2 flux estimates show appreciably smaller decadal trends than estimates based on changes in carbon inventory suggesting that methods capable of resolving shorter timescales are showing a slowing of the rate of ocean CO2 uptake. RECCAP model outputs for five decades show similar differences in trends between approaches.

Citation: Wanninkhof, R., Park, G.-H., Takahashi, T., Sweeney, C., Feely, R., Nojiri, Y., Gruber, N., Doney, S. C., McKinley, G. A., Lenton, A., Le Quéré, C., Heinze, C., Schwinger, J., Graven, H., and Khatiwala, S.: Global ocean carbon uptake: magnitude, variability and trends, Biogeosciences, 10, 1983-2000,, 2013.
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