Ocean currents are the continuous, predictable, directional movement of seawater driven by gravity, wind (Coriolis effect), and differences in water density. Ocean currents are horizontally moving ocean water.

Ocean currents play an important role in regulating the climate on Earth in the following ways:

• Redistribution of global heat: Ocean currents act much like a conveyor belt, transporting warm water and precipitation from the Equator toward the poles and cold water from the poles back to the tropics influencing local and global climate. For example, the North Atlantic Drift keeps the coasts of the North Sea (western coast of Europe) warm.
• Influences regional weather phenomenon: The changes in equatorial upwelling and currents play central roles in driving the El Niño and La Niña phenomena, thus influencing global climate patterns like the Indian monsoons, rainfall variability in Southern America and Pacific region, etc.
• Amount of precipitation: Oceans form an essential part of the Earth’s water cycle as most evaporation comes from the oceans and most precipitation falls on the oceans. Warm currents flow along the east coast of continents resulting in warm and rainy climates while cold currents flow along the west coast of continents.
• Formation of deserts on the West Coast: Cold ocean currents have a direct effect on desert formation in the West Coast regions of the tropical and subtropical continents. For example, Peru’s cold-water current of the Southeast Pacific Ocean is a primary reason for the aridity of the Atacama Desert (the driest desert in the world).
• Tropical cyclones: Ocean currents pile up warm waters in the tropics and this warm water is the major force behind tropical cyclones.

Ocean currents also play a profound role in supporting marine life, as discussed below:

• Ocean currents impact the connectivity of marine populations, as they influence the migration of strong swimmers, including whales and turtles.
• They act as carriers of dissolved carbon dioxide and organic matter in the form of small creatures, such as plankton, which constitute a major food source for many organisms like fishes thus creating the foundation of the global food web of species.
• Changes in ocean circulation influence the rate of nutrient supply from depths to the surface thus carrying reproductive cells and ocean life to new places. For instance, the Southern Ocean is a major player in this balance, as its upwelling supplies nutrients for 75% of global primary productivity.
• The meeting of the cold and warm currents provides a conducive ground for the breeding of fish across the Eastern coasts of continents. For example, the meeting of the Labrador (cold) and Gulf Stream (warm) currents near Newfoundland, the meeting of the Oyashio (cold) and Kuroshio (warm) currents near the coast of Japan, etc.

Ocean currents are critical to the interrelated and integrated global climate system, which not only keeps the globe habitable but also constitutes and supports the biodiversity on the planet.