Hydrographic time series in the northeast North Atlantic and Nordic Seas show that the freshening trend of the 1960s–1990s has completely reversed in the upper ocean. Since the 1990s temperature and salinity have rapidly increased in the Atlantic Inflow from the eastern subpolar gyre to the Fram Strait. In 2003–2006 salinity values reached the previous maximum last observed around 1960, and temperature values exceeded records. The mean properties of the Atlantic Inflow decrease northwards, but variations seen in the eastern subpolar gyre at 57°N persist with the same amplitude and pattern along the pathways to Fram Strait. Time series correlations and extreme events suggest a time lag of 3–4 years over that distance. This estimate allows predictions to be made; the temperature of Atlantic water in the Fram Strait may start to decline in 2007 or 2008, salinity a year later, but both will remain high at least until 2010.

[1] Hydrographic CO 2 system data obtained from World Ocean Circulation Experiment (WOCE) transatlantic zonal section A5 across 24.5°N and Florida Straits are described. By combining CO 2 measurements with hydrographic velocity calculations, the zonal and vertical variability of meridional fluxes of total alkalinity (TA), total dissolved inorganic carbon (TIC), and anthropogenic CO 2 (dC) are estimated. The resulting CO 2 fluxes are examined in four geostrophic mid-ocean zones as well as in the Gulf Stream flow through Florida Straits and in the surface ageostrophic Ekman flow. This method allows an estimate of the net budgets of these chemical species in the system considering together the Arctic and Atlantic Oceans north of 24.5°N. Taking into account the net flux contribution through Bering Strait, total meridional transports of chemical properties across 24.5°N latitude are also estimated. The slightly divergent net TA budget (À460 ± 200 kmol s À1 ) suggests that the North Atlantic is a small alkalinity source. The divergent TIC budget (À2430 ± 200 kmol s À1 or À0.92 ± 0.08 GtC yr À1 ) suggests that the North Atlantic is a source of TIC and therefore a net sink for atmospheric CO 2 . This value is twice as large as a previous estimation made from a poorly sampled section. Surprisingly, the North Atlantic Ocean appears to act as a net sink of anthropogenic CO 2 (+630 ± 200 kmol s À1 or +0.24 ± 0.08 GtC yr À1 ) and therefore a weak source of anthropogenic CO 2 to the atmosphere. Its main contributor is the intense northward flux in the Florida Current (+1280 ± 100 kmol s À1 ). The calculations imply a divergent inorganic carbon budget of À3060 ± 200 kmol s À1 or À1.16 ± 0.08 GtC yr À1 in preindustrial times (TIC 278 , when the molar fraction of CO 2 in the atmosphere was 278.2 ppm). This means that the North Atlantic would have had a 25% stronger divergence of TIC prior to the beginning of anthropogenic CO 2 penetration.

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[1] The extremely cold and dry winter of 2005 in southwestern Europe caused a profound transformation of the upper ocean hydrographic structure of the Bay of Biscay area, making it completely different from the previous decade. The strong local winter cooling resulted in the highest density flux estimated since the 1960s. The extreme buoyancy loss triggered the mixed layer to reach unprecedented depths affecting directly the level of local modal waters that are usually unconnected to air-sea interaction. The water column just below the climatological average mixed layer entered in a process of quick cooling that compensated in 2 years the 0.5°C gained in the period 1994-2004. Enhanced by a pronounced precipitation deficit the event caused concurrently a downward salt injection that made deeper levels of East North Atlantic Central Water begin a process of warming by isopycnal change, something never observed during the 1990s. As an overall result, the stratification of the upper permanent thermocline was dramatically reduced. The observed cold low stratification anomaly had a substantial spatial extent and remained for 2 years below the seasonal thermocline development, constituting a typical case of the reemergence mechanism, but was abruptly interrupted in the warmest winter on record of 2007. In addition to the hydrographic changes, the winter 2005 event had a notable effect on the marine ecosystem.

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