Where do all cold and warm ocean currents originate?

How do ocean currents originate and effect earths climate?

• OMG! please help! I don't know!

• Answer:

  Excellent question. I agree it's heat transport from the equator to the poles. If these currents change, which is a prediction for past causes/triggers of glaciation, the regulation of heat around the earth can be disrupted. Warm water near the equator can hold lots of salt. The water is transported to the pole where the water cools, and as a result, cannot hold as much salt. The saltier water is now denser and falls to the bottom of the ocean and flows back to the equator. The best example is in the Atlantic ocean with the Gulf Stream transporting heat to the pole, and the NADW (north atlantic deep water) current returning the water to the equator. The thermohaline current doesn't stop there, it eventually rounds The Horn, past the Indian Ocean, to the Pacific ocean. Does a huge clockwise turn in the pacific and proceeds back to the Atlantic Ocean. There are also other major ocean currents. For many awesome maps, check http://web.viu.ca/earle/geol-412/climate-system.pdf. In summary, their effect on climate is a mediating effect, dispersing heat throughout the planet. Also, if the current changes, and suddenly parts of the ocean experience a sudden increase in temperature, creatures could go extinct, or it could trigger a release of methane hydrate in the ocean sediment that would cause a huge extinction of benthonic life. I hope this helped.