Ocean Currents: Types, Causes, Major Warm & Cold Currents

Q: What are Ocean Currents?

Ocean currents are continuous movement of sea water in a direction which are generated by gravity, wind, and water density.

Updated on September 24, 2026Author:NEXT IAS Contributors

Ocean Currents are the global climate regulators. They are continuous and direction oriented movements of seawater driven by wind, density differences and rotation of Earth. They are responsible for the movement of heat and nutrients on earth. Interestingly, the Gulf stream transports over 100 times more water than all the rivers on our planet. This phenomenon keeps the western Europe warmer as compared to the polar latitudinal regions. The changes in ocean currents may affect rainfall, fisheries production, and global climate patterns.

List of Major Cold and Warm Ocean Currents

S.No.	Warm Ocean Currents	Cold Ocean Currents
1	North Equatorial Current	Labrador Current
2	South Equatorial Current	East Greenland Current
3	Gulf Stream	Canary Current
4	North Atlantic Drift	Benguela Current
5	Norwegian Current	Falkland Current
6	Brazil Current	California Current
7	Guinea Current	Peru (Humboldt) Current
8	Kuroshio (Japan) Current	Oyashio Current
9	North Pacific Drift	West Australian Current
10	Alaska Current	West Wind Drift or Antarctic Circumpolar Current
11	East Australian Current	Antarctic Coastal Current or East Wind Drift
12	Mozambique Current	Baffin Island Current
13	Agulhas Current	-
14	East Madagascar Current	-
15	Monsoon Drift or Monsoon Current	-

Causes of Ocean Currents

An ocean current is usually strongest at the surface and decreases in speed with depth. The ocean currents are primarily caused by the following factors on earth:

Planetary Winds

The movement of water on the surface of the ocean is influenced by the wind blowing over it. The friction between the wind and the water's surface impacts the direction and speed of the water's movement.
It is important to understand that the wind affects the momentum of the water, but it does not initiate the movement.
A notable example of the impact of prevailing winds on ocean currents can be observed in the North Indian Ocean.
In this region, the direction of the current completely changes when the monsoon winds reverse.

Temperature

The movement of ocean water, both on the surface and below it, is initiated by temperature differences. The temperature of the ocean water at the equator differs significantly from that at the poles.
The solar energy heats the water, causing it to expand. As a result, there is an 8 cm gradient between the elevated equatorial water and the middle latitude. This gradient causes the water to flow downhill.
Due to its lower density, the warm water moves from areas of lower density to areas of higher density. On the other hand, the denser cold water sinks.
The warm equatorial water slowly moves towards the poles along the surface, while the colder polar water slowly creeps along the bottom towards the equator.

Ocean Salinity

The ocean salinity often varies with evaporation, rainfall, influx of rivers in ocean water, formation and melting of ice. If the salinity is higher in ocean water then the water density drives the thermohaline circulation and deep ocean currents.

Coriolis Force

The coriolis force is the movement of air and water which is caused by the rotation of the earth. It is zero at the equator and maximum at the poles. It deflects the direction to the right in the northern hemisphere and to the left in the southern hemisphere. This force affects wind belts, cyclones and the path of ocean currents which creates a large circular ocean circulation system called gyres.

Coastal Configuration

The coastal alignment and presence of underwater ridges play an important role in determining the direction of ocean currents. The shape of the land also influences the flow of these currents. For example, the equatorial ocean current is divided into two branches after encountering the Brazilian coast.

Major Types

On the Basis of Depth

Surface currents make up approximately 10% of the total volume of water in the ocean, specifically referring to the upper 400 meters.
On the other hand, deep water currents account for the remaining 90%.
These currents circulate throughout the ocean basin as a result of density and gravity fluctuations.

On the Basis of Temperature

Cold Current:

Ocean currents play a significant role in distributing cold water to warmer areas. They move from the polar regions towards the equator.
Typically, these currents are observed along the west coast of continents in the low and middle latitudes, regardless of the hemisphere.
In the northern hemisphere, however, they are more commonly found along the east coast in higher latitudes.

Warm Current:

Warm water is moved to colder areas by ocean currents. These currents move from the equatorial regions towards the poles.
These particular currents are located on the eastern coasts of continents in the low and middle latitudes, which is true for both hemispheres.
In the northern hemisphere, these currents can also be found along the western coasts of continents in higher latitudes.

Some Other Prominent Terms

Gyre

A Gyre is a term used to describe a vast system of rotating ocean currents, particularly those influenced by large wind movements. These currents are generated by the Coriolis force.

Drift

When ocean water is propelled forward by prevailing winds, it is referred to as Drift. The term "drift" is also used to measure the speed of an ocean current, which is typically measured in knots.
Example - The North Atlantic Drift.

Streams

On the other hand, when a substantial body of ocean water moves along a defined path, resembling a large river on land, it is known as a Stream.
Streams tend to have a higher velocity compared to drifts.
Example - The Gulf Stream.

Eddies

Ocean eddies are swirling and rotating masses of water which occur within ocean currents. They can impact regional oceanic and atmospheric conditions.