The North Atlantic Drift is a powerful, warm surface current that moves vast quantities of water across the North Atlantic Ocean. This oceanic feature transfers heat from tropical regions toward higher northern latitudes. The current plays a significant role in regulating global ocean temperatures and distributing heat around the planet. Its influence extends far beyond the ocean, profoundly affecting the atmosphere and the climate of nearby continents.
Defining the North Atlantic Drift
The North Atlantic Drift, also known as the North Atlantic Current, is the broad, northeastward extension of a larger current system originating in the tropical Atlantic. It begins east of North America, diffusing after passing the Grand Banks off Newfoundland. This shift marks its transition from a relatively fast, narrow stream into a much wider, shallower, and slower flow.
As a surface current, the North Atlantic Drift is characterized by waters significantly warmer than the surrounding ocean at those northern latitudes. The current can widen to several hundred miles across as it crosses the mid-ocean. This warm water continues its path across the ocean basin before splitting into several branches near the continental shelf of Europe. One major branch flows north along the coast of Norway, while another turns south to become the Canary Current.
The Engine of the Current
The movement of the North Atlantic Drift is maintained by two distinct yet interconnected physical forces. The first is wind-driven circulation, where the prevailing Westerly winds act on the ocean surface. These persistent winds push the surface water eastward and poleward, providing the initial momentum for the current’s broad, shallow flow.
The second, more complex force is related to density differences, known as thermohaline circulation. This process is driven by variations in temperature and salinity, which determine water density. Warm, salty surface water traveling north releases heat to the atmosphere, causing it to cool and become denser.
When this water reaches the far northern latitudes, particularly in the Greenland and Norwegian Seas, it becomes cold and dense enough to sink to the deep ocean floor. This sinking water forms the North Atlantic Deep Water, which then flows south as a deep-water current. This deep-water movement must be replaced by warm surface water flowing from the south, effectively pulling the North Atlantic Drift northward to maintain the global circulation system.
Climate Moderation in Europe
The most renowned effect of the North Atlantic Drift is its moderation of the climate in Western Europe. The current transports vast amounts of thermal energy from the tropics to the high northern latitudes. As this warm water flows, it transfers heat into the overlying atmosphere.
The prevailing Westerly winds pick up this warmed, moist air and transport it inland across the European continent. This delivery of warmth results in significantly milder winter temperatures along the western seaboard. Winters in the British Isles are estimated to be more than 5°C warmer than they would be without the current’s influence.
This climatic advantage is evident when comparing coastal regions in Europe with other landmasses located at similar latitudes. For instance, northern coastal Norway enjoys a temperate, ice-free winter, whereas the coast of Labrador, Canada, is characterized by severe cold and extensive sea ice. The North Atlantic Drift prevents the extreme seasonal temperature swings seen in continental regions, leading to a stable maritime climate.
Ecological and Economic Importance
Beyond its effect on continental climate, the North Atlantic Drift sustains rich ecological and significant economic activity. The movement of the warm current contributes to the mixing of water layers, which promotes nutrient upwelling in certain areas. This process supports the growth of phytoplankton, forming the base of a highly productive marine food web.
The warm waters affect the distribution and migration patterns of various fish species, making the North Atlantic one of the world’s most productive fishing grounds. Fisheries in regions like the North Sea and off the coast of Iceland depend heavily on the environment created by the current. Furthermore, the heat transferred by the current keeps many northern ports, particularly those along the coast of Norway, free of ice throughout the winter months. This maintenance of open, navigable waters facilitates year-round maritime trade and shipping, which is a major economic benefit for northern nations.