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Ocean Currents and Global Climate

Ocean currents are the continuous, directed movement of seawater generated by a number of forces, including wind, tides, and differences in water density. These currents are not just rivers within the ocean; they form a global circulation system that plays a fundamental role in regulating Earth's climate. One of their most important functions is to act as a massive heat-transport system, moving warm water from the equator toward the poles and cold water from the poles back toward the equator. This distribution of heat helps to moderate temperatures across the globe.

This global system is often called the "global conveyor belt," or more technically, the thermohaline circulation. The term "thermohaline" comes from "thermo" for heat and "haline" for salt content, the two main factors that determine water density. In the polar regions, particularly the North Atlantic, seawater gets very cold and salty, causing it to become dense and sink to the deep ocean. This deep water then flows slowly along the ocean floor. This process moves vast quantities of water and is a critical driver of global ocean circulation.

The climatic impact of this system is enormous. By transporting heat to higher latitudes, it significantly moderates regional climates. A prime example is the Gulf Stream, a powerful surface current that is part of the global conveyor belt. It brings warm water from the tropics to the coast of Western Europe, making its climate significantly milder than that of other regions at the same latitude, such as Canada. Without this oceanic heat transport, the temperature differences between the equator and the poles would be much more extreme.