The Arctic Ocean covers an area of about 13 million km², making it the World’s smallest ocean. It reaches depths of more than 4000 m. This ocean stretches over all the seas situated between the North Pole and the northern parts of Europe, Asia and America. It is connected with the north of the Atlantic Ocean, receiving an input of large bodies of water through the Barents Sea and the Fram Strait. It also has some contact with the Pacific Ocean, through the Bering Strait, but this passage is narrower.
The circulation of waters in the Arctic Ocean is a key player in World Ocean circulation and global climate regulation, owing particularly to the heat exchanges it effects with the atmosphere. When relatively warm, strongly saline water bodies moving from the Atlantic (by the Gulf Stream for example) arrive in the cold Arctic Ocean, where the resulting temperature decrease induces their density to rise. That causes them to plunge further down into deeper layers, forming deep-water masses. This process is “thermohaline circulation” (from Greek thermos, warm, and halos, salt). It moves slowly but over vast surface areas. Every winter therefore, several million km³ of water is driven towards the deeper zones, slowly moving water southwards, along the deep along the floor of the Atlantic Ocean. The slow mixing process in the oceans has been represented by oceanographers by a global-scale conveyor belt. Many other currents (surface, deep and mid-depth) circulate in the Arctic Ocean in a complex configuration. They include the Nansen currents, operating at the surface, which cause the sea-ice to drift. See opposite “Ocean currents and sea-ice expansion” for more information.
The Arctic Ocean is largely covered by a thick layer of sea-ice whose extent varies with the seasons. It is mobile, continually being fragmented and remodelled by the winds and currents. In summer, when the sea hardly freezes, the sea-ice breaks up into a multitude of floating islands of ice or floes. With the changing seasons, the covering of Boreal ice shifts between about 8 and 15 million km². In its central area the sea-ice can attain a thickness of 4 m.
UNEP/GRID-Arendal Maps and Graphics Library, 1997 Source AMAP Cartographer/Designer Philippe Rekacewicz, UNEP/GRID-Arendal