The study of mass water flows or currents is critical to appreciating how heat energy is cycled between the earth’s atmosphere, landmasses, and water bodies. More than 70% of the world is covered by ocean, which in turn holds more than 95% of the world’s total water making oceans a major influence in the transfer and storage of heat energy around the globe. As this heat energy moves through global and local ocean currents, it influences the cycling of gases, nutrient delivery to marine ecosystems, global climate pattern stabilization, and the regulation of local temperature extremes and weather conditions. The ocean currents tend to be located in water over 984 feet deep and also at the ocean surface, and can move vertically or horizontally at both local and global scale. Oceans have interconnected circulation or current systems, which are driven by solar energy, the earth’s rotation, tides, winds, and differences in water density.

Ocean currents are also influenced by nearby landmasses and ocean basin topography, which in turn affect the direction, speed, shape, and size of ocean currents. Surface ocean currents may happen at the global and local scale driven mostly by wind, leading to vertical and horizontal movement of water. Ocean surface currents, prevailing winds, and associated mixing of cold and warm water influence global climate. Further, differences in the density of ocean water lead to a circulation system at the global scale. This circulation, also referred to as the global conveyor belt, includes both deep and surface ocean currents circulating in a cycle lasting 1000 years around the globe. In this case, the warm surface currents tend to carry water with less density towards the poles from the equator, while the deeper ocean currents are colder and carry cold water with less density towards the equator and away from the poles.

This global circulation system plays a major role in heat energy distribution, cycling vital gases and nutrients while also regulating climate and weather. Famous ocean currents like the Gulf Stream have widely acknowledged impacts on climate and temperature. Northwestern Europe has a milder climate with regard to temperature than Northeastern U.S. and Canada, with approximately 300 to 400 Fahrenheit differences in air temperature between the two regions in January. The Gulf Stream brings in warm currents from Florida and the Caribbean along the U.S. coast and then to Europe across the Atlantic Ocean. The warming effect of this ocean current misses Canada and Northeast U.S. after taking a turn towards Europe near North Carolina, instead moving towards and reaching Ireland and England. In this case, the Gulf Stream sinks heat from the equatorial region in Florida and the Caribbean, distributing it to Europe and some parts of the Eastern U.S. coast.

Thus, it is highly likely that any slowdown or diversion of the Gulf Stream towards Europe would result in colder winters in Ireland and England. It is evident that ocean circulation is critical to distributing heat around the globe by absorbing majority of the sun’s radiation around the tropics, acting as a heat sink that retains heat and prevents its radiation back into space. Since oceans are constantly evaporating, this evaporation results in warming and increased humidity in the surrounding atmosphere. The continuous flow of ocean water currents, which is partially caused by salinity and temperature gradients, therefore allows for the transfer of heat from areas where excessive heat is absorbed by the ocean water and released into the atmosphere in areas with low temperatures. The main ocean current systems generally flow in a counterclockwise direction in the southern hemisphere and vice versa, creating circular patterns of heat distribution that tend to trace the continental coastlines.