What is the main driver of the thermohaline circulation?

Thermohaline circulation is primarily driven by differences in temperature and salinity in ocean water, which together affect its density. When water cools or has a higher salt concentration, it becomes denser and tends to sink. This process creates a global conveyor belt-like movement of water, affecting climate and nutrient distribution throughout the oceans.

In polar regions, where temperatures are low and salinity can be high due to ice formation, water becomes very dense and sinks. This cold, dense water then flows toward the equator at depth. Meanwhile, warmer water from tropical regions moves poleward at the surface to replace the sinking water, creating a continuous cycle. This interconnected movement of different water masses is crucial for regulating Earth's climate and sustaining marine ecosystems.

Other factors, such as wind and tidal forces, can influence surface currents, but they don't drive the thermohaline circulation itself. Likewise, while seabed features can affect local currents and water flow, they do not initiate the large-scale density-driven circulation of the ocean. Coral reef activities play a significant role in local ecosystems but are not a primary driver of global ocean circulation patterns.