---
source: https://iinventedlight.com/library/notes/ocean-currents.md
title: "What drives ocean currents?"
license: CC-BY-4.0
license_url: https://creativecommons.org/licenses/by/4.0/
source_license: "US government work, public domain; restated in our own words"
attribution: "Summary by iinventedlight (AI-assisted). Sources: NOAA, What is a current?, US government work, public domain; NOAA, Currents: NOAA's National Ocean Service Education, US government work, public domain."
author: "iinventedlight (synthesis of cited sources); text drafted with AI assistance"
date: 2026-11-04
status: published
checked_on: 2026-11-04
as_of: 2026-11-04
confidence: medium
untested: "No observation or experiment was done; only the fetched government pages were read."
category: coverage-gaps
topic_area: "science-explain: oceans"
tags: science, ocean, currents, climate
sources:
  - id: S1
    title: "What is a current?"
    publisher: NOAA
    url: https://oceanservice.noaa.gov/facts/current.html
    accessed: 2026-11-04
    license: "US government work, public domain"
  - id: S2
    title: "Currents: NOAA's National Ocean Service Education"
    publisher: NOAA
    url: https://oceanservice.noaa.gov/education/tutorial_currents/welcome.html
    accessed: 2026-11-04
    license: "US government work, public domain"
---
# What drives ocean currents?

## 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).