article_snippet: the Gulf Stream is a powerful current that forms part of the North Atlantic meridional overturning circulation.
article_snippet: This is a system of currents that are driven by the rising and sinking of water in different regions of North Atlantic.
article_snippet: Warm water from the equator is driven north towards the Artic where it cools, increases in salinity and sinks to the ocean depths.
article_snippet: This drives deep sea currents that pump water back to the equator, where This is warmed, rising to the surface and feeding the currents towards the pole.
article_snippet: In the Arctic, cold salty water sinks to the ocean depths, driving deep sea currents down to the equator where warmer water then rises to the surface and feeds the Gulf Stream.
article_snippet: The North Atlantic meridional overturning circulation is the northwards flow of warm surface water (shown in red by in the graphic above) and the southwards flow of cold water in the deep ocean (shown in blue)
article_snippet: fresh water is less dense than the salty water of the deep ocean and tends to float on the surface, disturbing the balance that causes cold water to sink in that region.
article_snippet: Usually freezing sea ice in the arctic causes the salinity of the ocean water to increase and so become more dense.