An ocean current is the steady movement of a large mass of seawater in a fixed direction. Currents are mainly caused by prevailing winds, differences in temperature and salinity, and the rotation of the Earth (Coriolis force). They strongly affect coastal climate, marine life and trade routes, which makes them a steady exam topic.
Warm (Hot) Ocean Currents
Warm currents flow from the equator towards the poles and carry warm water. They raise the temperature of the coasts they touch.
- Gulf Stream - North Atlantic Ocean; keeps Western Europe warm.
- Kuroshio (Japan) Current - North Pacific Ocean.
- North Atlantic Drift - extension of the Gulf Stream.
- Brazil Current and Agulhas Current in the Southern Hemisphere.
Cold Ocean Currents
Cold currents flow from the poles towards the equator and carry cold water. They lower the temperature of nearby coasts and often bring fog.
- Labrador Current - North Atlantic; meets the Gulf Stream near Newfoundland.
- Humboldt (Peru) Current - off the west coast of South America.
- Benguela Current - off the south-west coast of Africa.
- California Current and Canary Current.
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Effects of Ocean Currents
- The meeting of warm and cold currents forms the world's richest fishing grounds, such as the Grand Banks near Newfoundland where the Gulf Stream meets the Labrador Current.
- Warm currents bring rain to coasts; cold currents cause deserts on western coasts, like the Atacama (Humboldt) and Namib (Benguela).
- Mixing of currents causes dense fog, which is dangerous for shipping.
- The El Nino event is linked to a weakening of the cold Humboldt Current off Peru.
Quick Revision Points
- Currents are driven by winds, temperature, salinity and the Coriolis force.
- Warm currents move from equator to poles; cold currents from poles to equator.
- Gulf Stream warms Western Europe.
- Humboldt Current is cold and linked to El Nino.
- Grand Banks = famous fishing ground at the Gulf Stream-Labrador meeting point.
- Cold currents cause coastal deserts like Atacama and Namib.