The ocean is not a still body of water. The ocean conveyer system is caused by a combination of thermohaline currents (thermo = temperature; haline = salinity) in the deep ocean and wind-driven currents on the surface. 

Cold, salty water is dense and sinks to the bottom of the ocean while warm water is less dense and remains on the surface.

The ocean conveyor belt, also known as the thermohaline circulation, is a global system of ocean currents that plays a critical role in regulating Earth's climate. It transports warm water from the equator toward the poles and cold water from the poles back toward the equator, helping to distribute heat and maintain temperature balance across the planet. This process is essential for several reasons

By moving warm and cold water around the globe, the conveyor belt helps regulate temperatures, keeping equatorial regions from getting too hot and polar regions from getting too cold. This balance influences climate patterns and weather conditions in different regions.

As cold water sinks in the polar regions, it brings oxygen and nutrients from the surface down to the deep ocean. These nutrients support marine ecosystems by fueling plankton growth, which is the foundation of the marine food chain.

The conveyor belt transports carbon dioxide from the surface to the deep ocean, where it can be stored for centuries. This process helps regulate atmospheric CO₂ levels and, by extension, Earth's climate.

Many marine species depend on the conveyor belt's stable patterns to maintain their habitats. Sudden changes in ocean currents can disrupt the living conditions of various species, affecting biodiversity and ecosystem health. Many species also rely on currents to bring in food sources such as plankton.