In the North Atlantic Ocean, the warm surface currents from the south collide with the cold waters from the Norwegian Sea and the Arctic. Here is where the most important transformation of warm water masses into cold deep water takes place, and the western margin of the ocean is the initial formation region of the deep western boundary current, part of the global circulation or conveyor belt that transports cold and oxygen-enriched deep water southward into the subtropics, tropics and southern hemisphere, spreading into the other oceans as well. Of particular interest today are long-term variations of circulation and their effects on climate, CO2 uptake and the fresh water cycle. Hence we observe, in close collaboration with research groups of the other neighboring countries, the slow warming of the subpolar North Atlantic at depth, and one of the most pressing questions is whether these changes have an impact on the North Atlantic circulation, in particular, whether the deep western boundary current weakens as a result of this warming.