A. Corbière 1 , N. Metzl 1 , S.R. Ólafsdóttir 2 , J. Olafsson 2 , T. Johannessen 3 , A. Olsen 3 ,

1. The rapid decrease of the North Atlantic carbon sink Winter (December to March) in situ observations Grey bars represent the NAO index from Hurrell fCO2oc averaged for each cruise fCO2oc measured continuously onboard the M/VSkògafoss fCO2oc measured continuously onboard the M/VNuka Arctica fCO2atm measured at Mace Head 2001-2008 5.5 to 7.1 µatm.year-1 Change in seawater chemistry (increase in DIC and decrease of Alkalinity) due to recent increase of convective processes/vertical mixing explained mainly (>95%) the rapid increase of fCO2oc A. Corbière1, N. Metzl1,S.R. Ólafsdóttir2, J. Olafsson2, T. Johannessen3,A. Olsen3, D. Pierrot4, M. Ramonet5 G. Reverdin1,T. Takahashi6 andR. Wanninkhof4 1Laboratoire d’Océanographie et du Climat: Expérimentation et Approches Numériques (LOCEAN - IPSL), Université Pierre et Marie Curie, Paris, France 2Marine Research Institute and University of Iceland, Reykjavik, Iceland 3Bjerknes Centre for Climate Research, University of Bergen, Bergen, Norway 4Atlantic Oceanographic and Meteorological Laboratory, 4301 Rickenbacker Causeway, Miami, FL, USA 5LSCE - IPSL, Gif sur Yvette, France 6Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY 10964, USA Interannual variability of sea surface temperature (T), salinity (S), Dissolved Inorganic carbon (DIC) and Total Alkalinity (TA) over the period 1993-2008. Focus on the open ocean region (53-62°N) Trend analysis will be based on winter data only Aim of this analysis Extending the previous analysis of Corbière et al. [2007] Estimating the drivers of the surface fCO2oc evolution The decadal trends of oceanic carbon properties will be determined in two regions The fCO2oc trends based on DIC and TA data are also compared with direct fCO2oc measurements Determination of the surface fCO2oc evolution drivers depending on time and location This rapid fCO2oc growth rate has never been observed in the North Atlantic or in any other oceanic region and is confirmed by onboard fCO2 measurements 1993-2003 3.6 ±0.4 µatm.year-1 Drivers of the surface fCO2oc trend ? ? Sea surface warming is the major driver (>75%) explaining the rise of fCO2oc ACKNOWLEDGEMENTS The SURATLANT Project is supported by INSU and IPEV in France. This work is also supported by French program FlamenCO2, a component of SOLAS-France. We thank the EIMSKIP Company, the captains and crews of the M/VSkògafoss, M/V Godafoss, M/V Selfoss and M/V Reykjafoss, and all the very helpful embarked observers for their cooperation in this work. We thank Magnus Danielsen for salinity analysis done at the Marine Research Institute in Reykjavik. We also thank the Service National d’Analyse des Paramètres Océanique du CO2 (SNAPO-CO2) at LOCEAN/IPSL for DIC and TA analysis. The European Integrated Project CARBOOCEAN 511176 also contributes to this study. REFERENCES Corbière, A., Metzl, N., Reverdin, G., Brunet, C., Takahashi, T., 2007. Tellus 59B,168-178. Corbière, A., Metzl, N., Ólafsdóttir, S.R., Olafsson, J., Olsen, A., Pierrot, D., Ramonet, M., Reverdin, G., Takahashi, T. and Wanninkhof, R. 2008. Recent acceleration of the sea surface fCO2 growth rate in the North Atlantic Supolar Gyre (1993-2008). In prep. Schuster, U., Watson, A.J., Bates, N., Corbière, A., Gonzalez-Davila, M., Metzl, N., Pierrot, D., Santana-Casiano, M. 2009. Trends in North Atlantic sea surface fCO2 from 1990 to 2006. Deep-Sea Res II, special issue SOCOVV, in press.