A. Corbière1, N. Metzl1, S.R. Ólafsdóttir2, J. Olafsson2, T. Johannessen3, A. Olsen3,D. Pierrot4, M. Ramonet5 G. Reverdin1, T. Takahashi6 and R. 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, France6Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY 10964, USA

The rapid decrease of the North Atlantic carbon sink

Focus on the open ocean region (53-62°N)Trend analysis will be based on winter data only

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

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.

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/V Skògafoss, 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.

Drivers of the surface fCO2oc trend

1993-20033.6 ±0.4 µatm.year-1

Sea surface warming is the major driver (>75%) explaining the rise of fCO2

oc

? ?

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 fCO2

oc

2001-2008 5.5 to 7.1 µatm.year-1

fCO2oc averaged for each cruise

Grey bars represent the NAO index from Hurrell

Winter (December to March) in situ observationsfCO2oc measured continuously onboard the M/V Skògafoss

fCO2oc measured continuously onboard the M/V Nuka Arctica

fCO2atm measured at Mace Head

Aim of this analysisExtending the previous analysis of Corbière et al. [2007]

Estimating the drivers of the surface fCO2oc evolution

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

Interannual variability of sea surface temperature (T), salinity (S), Dissolved Inorganic carbon (DIC) and Total Alkalinity (TA) over the period 1993-2008.