| Summary: | 11 pages, 4 figures. The anthropogenic CO2 (C-ant) estimates from cruises spanning more than two decades (1981–2006) in the Irminger Sea area of the North Atlantic Subpolar Gyre reveal a large variability in the C-ant storage rates. During the early 1990’s, the C-ant storage rates (2.3 ± 0.6 mol C m−2 yr−1) doubled the average rate for 1981–2006 (1.1 ± 0.1 mol C m−2 yr−1), whilst a remarkable drop to almost half that average followed from 1997 onwards. The C-ant storage evolution runs parallel to chlorofluorocarbon-12 inventories and is in good agreement with C-ant uptake rates of increase calculated from sea surface pCO2 measurements. The contribution of the Labrador Seawater to the total inventory of C-ant in the Irminger basin dropped from 66% in the early 1990s to 49% in the early 2000s. The North Atlantic Oscillation shift from a positive to a negative phase in 1996 led to a reduction of air-sea heat loss in the Labrador Sea. The consequent convection weakening accompanied by an increase in stratification has lowered the efficiency of the northern North Atlantic CO2 sink. This work was developed and funded by the OVIDE research project from the French research institutions IFREMER and CNRS/INSU and by the European Commission within the 6th Framework Programme (EU FP6 CARBOOCEAN Integrated Project, Contract no. 511176). Marcos Vázquez-Rodríguez is funded by Consejo Superior de Investigaciones Científicas (CSIC) I3P predoctoral grant program REF.: I3P-BPD2005. Peer reviewed
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