Circulation in the Ocean — Passage and Quiz

Ocean circulation refers to the large-scale movement of seawater around the globe. It is driven by a combination of factors, including wind, temperature, salinity, and the Earth’s rotation. Ocean circulation plays a crucial role in regulating the Earth’s climate and distributing heat and nutrients.

The ocean’s circulation system is divided into two main components: surface currents and deep ocean currents. Surface currents are driven by wind and affect the upper 400 meters (1,300 feet) of the ocean. Deep ocean currents, also known as the thermohaline circulation, are driven by differences in water density caused by temperature and salinity.

One of the most important features of ocean circulation is the global conveyor belt, a slow-moving current that transports water around the world. Warm surface water flows from the equator toward the poles, where it cools, becomes denser, and sinks. This cold, dense water then flows back toward the equator, completing the cycle.

Ocean circulation also affects marine ecosystems by transporting nutrients and oxygen. For example, upwelling brings nutrient-rich deep water to the surface, supporting plankton growth and, in turn, larger marine animals.

Fun fact: The global conveyor belt takes about 1,000 years to complete one full cycle, making it one of the slowest processes on Earth!