The three-dimensional ocean circulation is hardly observable but its quantification has greatly improved over the last two decades, due to moored array observations, deep float trajectories and satellite altimetry. Historical temperature and salinity data reveal changes on various periods in the North Atlantic: a global warming trend of the upper layers, quasi-decadal and multidecadal oscillations. The associated changes in the circulation are not yet clearly determined, but some hints from observations and models are presented.