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Flows of water in Earth ’s seas have guided navigator for centuries and shape climate for much longer . But how did ocean currents first emerge ?
These flows would have appeared with the planet ’s first ocean , around 4 billion to 4.5 billion years ago , spurred by the same forces that propel them today : lead , tide , global divergence in temperature and coarseness , and the planet ’s gyration .
A visualization of ocean currents.
Ocean currents behave much like rivers within the declamatory dead body of water supply , according to theUniversity of Hawaiʻi at Mānoa . They range in size of it from small current near beaches to sea - spanning flows , like the tremendous gyres , or elliptic cycles , that ophidian between continents . For example , in the North Atlantic Gyre , water course west along the equator , north past the U.S. East Coast in the Gulf Stream , back east along the Arctic , then south past Europe and Africa as the Canary Current .
twist , powered by solar zip , direct surface currents , like those in coil . difference in temperature and saltiness between the equator and Earth ’s poles magnate thick - water currents known as thermohaline ( for " hotness " plus " salt " ) circulation . It can take a thousand year to complete a global thermohaline cycle , James Potemra , a prof at the University of Hawaiʻi at Mānoa Institute of Geophysics and Planetology , tell Live Science . Tides make smaller currents , while Earth ’s spin pushes scroll clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere ( the so - foretell Coriolis effect ) .
As soon as the satellite ’s first oceans seem , they would have experience like forces , Roger Fu , a prof in the Department of Earth and Planetary Sciences at Harvard University , told Live Science . So , see the growth of currents comes down to timing the birth of oceans . " Earth had the same sorts of temperature gradient back in the other days as now , because the equator is hot , " Fu allege . " So , it would have had currents . "
A visualization of ocean currents.
Conservative estimates put the sea ’s age at 3.8 billion years , Fu say . However , ancient zirconium silicate crystals in Australiabear evidence of sea urine 4.4 billion eld ago , or about 100 million years after Earth form . " So very early in Earth ’s account , we would have had ocean , " Fu say .
Same forces, different shapes
Primeval current form would have been very different , however . The continents have shift position drastically , likely all joined together in supercontinents at various times , with other configurations in between . That would have changed the paths surface current carry , with no pocket between the Old and New world to forge the North Atlantic Gyre , for good example .
— Massive supercontinent will form hundreds of millions of class from now
— Ocean current are getting faster
World map with major marine currents.
— What ’s the largest ocean that ever live on Earth ?
On billion - class timescales , " the sea currents are pass to be completely unrecognizable , because the continents were unrecognizable , " Fu order . dissimilar continental positions would have alter deep ocean currents , too , Potemra said , with thermohaline current enjoy largely unblocked paths from the equator to the pole , for representative .
Because of the time it takes for continent to appreciably change configuration , though , flow seem everlasting on human timescales . Today ’s major currents " probably number into existence … millions of years ago because of some continent rearrangement , " Fu suppose .
The movement of mainlands due to continental drift would have had an effect on ocean currents.
Historical records , in fact , show the long doggedness of today ’s currents . " It was Benjamin Franklin that first discovered the Gulf Stream , because he noticed when the ships came over that this current … would take them north very apace , " Potemra say . " And the Vikings would have experience the Gulf Stream . "
