The Labrador Current is a major cold-water current flowing southward in the North Atlantic Ocean, representing a significant component of global ocean circulation. This slow-moving body of water transports frigid, low-salinity water from the Arctic into the mid-latitudes, profoundly influencing the marine environment and climate of eastern North America. It shapes weather patterns and creates unique marine ecosystems. Understanding this current is fundamental to grasping the dynamic interplay between the Arctic and the warmer North Atlantic.
Geographical Path and Characteristics
The current’s journey begins in the Arctic, originating from a confluence of waters that includes the Baffin Island Current, a branch of the West Greenland Current, and inflow from the Hudson Strait. These sources converge in the Labrador Sea, establishing the current’s initial characteristics before it flows south. It then travels along the continental shelf break, hugging the coasts of Labrador and Newfoundland.
As a cold boundary current, it is characterized by extremely low temperatures, often maintaining surface water near or below 0°C (32°F) in some sections. Its salinity is also lower than the open North Atlantic, typically ranging between 30 and 34 parts per thousand, due to the substantial input of freshwater from Arctic meltwater and river runoff. This current is relatively deep, extending to depths of up to 2,500 meters in its deeper slope branch.
The current continues its trajectory southward until it reaches the Grand Banks, a vast underwater plateau southeast of Newfoundland. This area marks a dramatic boundary where the cold, southward-flowing Labrador Current meets the warm, northward-flowing Gulf Stream. This intense oceanographic convergence creates a sharply defined front, which is a significant factor in the regional climate and ecology.
Driving Forces and Mechanism
The movement of the Labrador Current is primarily sustained by density-driven circulation, a mechanism known as thermohaline flow. The water masses that feed the current are exceptionally cold and relatively fresh, making them denser than the surrounding North Atlantic water. This density difference causes the water to sink and flow southward along the continental slope, replacing deeper water masses.
This process is part of the larger Atlantic Meridional Overturning Circulation (AMOC), where cold, dense water sinks in the North Atlantic and drives a global conveyor belt of ocean currents. The current’s path is also influenced by the Coriolis effect, the force resulting from the Earth’s rotation.
This force deflects the moving water to the right in the Northern Hemisphere, which helps to pin the current against the western boundary of the North Atlantic basin. While the deep flow is largely density-driven, the surface component of the current is also subject to wind stress, which contributes to its overall speed and variability.
Influence on Regional Climate and Iceberg Transport
The Labrador Current exerts a cooling influence on the climate of the Canadian Maritimes and the northeastern United States coast. By transporting cold Arctic water south, it significantly lowers sea surface temperatures along the shorelines it passes. This chilling effect results in coastal areas being noticeably colder than European regions situated at similar latitudes, which are instead warmed by the Gulf Stream and North Atlantic Drift.
The current is also the primary conveyor belt for a substantial number of icebergs, earning the region the nickname “Iceberg Alley.” These massive blocks of glacial ice, calved mainly from the glaciers of Greenland, are carried southward by the cold current into the transatlantic shipping lanes. An average of several hundred icebergs each year travel far enough south to pose a hazard to navigation.
The greatest danger zone is found near the Grand Banks, where the icebergs are pushed directly into the busy routes used by commercial vessels. The 1912 sinking of the Titanic spurred the establishment of the International Ice Patrol to track the hazardous ice.
Ecological and Economic Significance
The convergence zone at the Grand Banks, where the Labrador Current meets the Gulf Stream, supports one of the world’s most biologically productive marine environments. The mixing of the cold, dense Labrador Current water with the warmer Gulf Stream water creates an upwelling effect. This process brings nutrient-rich water from the ocean floor to the surface layer, fueling massive plankton blooms.
These blooms form the base of an extensive food web, supporting large populations of commercially valuable fish species, including cod, haddock, and various shellfish. The resulting rich fishing grounds have historically sustained significant economic activity for the coastal communities of Newfoundland and Labrador.
The sharp temperature contrast between the warm, moist air over the Gulf Stream and the cold Labrador Current water frequently generates dense, persistent fog over the Grand Banks. This fog severely limits visibility and compounds the danger posed by the icebergs also carried by the current.