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Short answer

Ocean currents are driven by three main things: tides, wind, and thermohaline circulation (density differences from temperature and salinity). [S1][S2]

The three drivers

1. Tides make tidal currents, strongest near shore, in bays and estuaries, and very predictable. [S1]
2. Wind drives currents at or near the surface, from local coastal upwelling to ocean-wide flows. [S1][S2]
3. Thermohaline circulation moves water because cold, salty water is denser; it runs at both deep and shallow levels. [S1][S2]

Why it matters

Currents carry warm water from the equator and cold water from the poles, shaping climate. The Gulf Stream gives Bergen, Norway milder winters than New York. [S1] Speeds are given in meters per second or knots (1 knot is about 1.15 mph). [S1]

Claims

• id: C1 claim: Ocean currents are driven by wind, density differences and tides. source: S1 evidence: "Ocean currents are driven by wind, water density differences, and tides."
• id: C2 claim: Tidal currents change in a regular, predictable pattern. source: S1 evidence: "Tidal currents change in a very regular pattern"
• id: C3 claim: Thermohaline circulation is driven by density differences from temperature and salinity. source: S2 evidence: "a process driven by density differences in water due to temperature (thermo) and salinity"
• id: C4 claim: Currents are essential for maintaining the balance of life on Earth. source: S2 evidence: "Currents are essential for maintaining the existing balance of life on Earth"

Sources

• [S1] What is a current?. NOAA. https://oceanservice.noaa.gov/facts/current.html . License: US government work, public domain. Accessed 2026-11-04.
• [S2] Currents: NOAA's National Ocean Service Education. NOAA. https://oceanservice.noaa.gov/education/tutorial_currents/welcome.html . License: US government work, public domain. Accessed 2026-11-04.

License: this note is CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Summary by iinventedlight (AI-assisted).

@misc{iil_note_6yn1bsyy,
  author = {{iinventedlight}},
  title = {{What drives ocean currents?}},
  howpublished = {iinventedlight Library},
  year = {2026},
  date = {2026-11-04},
  url = {https://iinventedlight.com/library/notes/ocean-currents/},
  note = {Permanent ID iil:note:6yn1bsyy. License: CC-BY-4.0.},
}

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