Biogeosciences www.biogeosciences.net 1726-4170 1726-4189 2 1 2005 10.5194/bg-2-87-2005 http://www.biogeosciences.net/2/87/2005/ http://www.biogeosciences.net/2/87/2005/bg-2-87-2005.html http://www.biogeosciences.net/2/87/2005/bg-2-87-2005.pdf 87 96 2005-03-07 The carbon budget of the North Sea H. Thomas Y. Bozec H. J. W. de Baar K. Elkalay M. Frankignoulle L.-S. Schiettecatte G. Kattner A. V. Borges Canada Research Chair, Dalhousie University, Department of Oceanography, 1355 Oxford Street, Halifax, Nova Scotia B3H 4J1, Canada Royal Netherlands Institute for Sea Research (NIOZ), P.O. Box 59, 1790 AB Den Burg, Texel, The Netherlands Chemical Oceanography Unit, MARE, University of Liège, Institut de Physique (B5), 4000 Liège, Belgium Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany A carbon budget has been established for the North Sea, a shelf sea on the NW European continental shelf. The carbon exchange fluxes with the North Atlantic Ocean dominate the gross carbon budget. The net carbon budget – more relevant to the issue of the contribution of the coastal ocean to the marine carbon cycle – is dominated by the carbon inputs from rivers, the Baltic Sea and the atmosphere. The North Sea acts as a sink for organic carbon and thus can be characterised as a heterotrophic system. The dominant carbon sink is the final export to the North Atlantic Ocean. More than 90% of the CO₂ taken up from the atmosphere is exported to the North Atlantic Ocean making the North Sea a highly efficient continental shelf pump for carbon.