The Gulf Stream is a warm and fast ocean current in the Atlantic Ocean. It begins in the Gulf of Mexico, flows through the Straits of Florida, and moves up the eastern coast of the United States. Near North Carolina, it turns east and becomes the North Atlantic Current, which travels toward Northwest Europe. The process of western intensification causes the Gulf Stream to speed up as it moves north along the east coast of North America. Near 40°N latitude and 30°W longitude, the current splits into two parts. The northern part, called the North Atlantic Drift, moves toward Northern Europe, while the southern part, called the Canary Current, flows back toward West Africa.
The Gulf Stream affects the climate of the East Coast of the United States, from Florida to southeast Virginia, and has a stronger influence on the climate of Northwest Europe. Scientists agree that the warm North Atlantic Current helps make the climate of Northwest Europe warmer than other areas at the same latitude. The Gulf Stream is part of the North Atlantic Gyre. Its presence contributes to the formation of strong storms, both in the atmosphere and in the ocean.
History
The European discovery of the Gulf Stream is linked to the 1512 voyage of Juan Ponce de León. After this journey, Spanish ships often used the Gulf Stream to travel from the Caribbean to Spain. A summary of Ponce de León’s voyage log from April 22, 1513, described the current as so strong that even with strong winds, ships were pushed backward instead of forward. The log noted that the current’s power seemed greater than the wind’s.
Benjamin Franklin became interested in how ocean currents move in the North Atlantic. In 1768, while in England, Franklin heard a question from the Colonial Board of Customs: Why did British ships take longer to travel from England to New York than American merchant ships took to go from London to Newport, Rhode Island? The American ships had to sail farther, traveling down the River Thames and across the English Channel before crossing the Atlantic, while the British ships left from Falmouth, Cornwall.
Franklin asked his cousin, Timothy Folger, a whaling captain from Nantucket, for an explanation. Folger explained that American ships often sailed with the Gulf Stream, which was identified by whale behavior, water temperature, and changes in water color. However, British mail ships traveled against the current. Franklin asked Folger to draw the path of the current on an Atlantic map and add notes about avoiding it when sailing from England to America. Franklin sent the map to Anthony Todd, the British Post Office’s secretary. The map was printed in London in 1769 but was mostly ignored by British captains. A copy was printed in Paris between 1770 and 1773, and Franklin published another version in Philadelphia in 1786.
Since the mid-20th century, improvements in ocean study have increased scientific knowledge of the Gulf Stream. In the 1950s and 1960s, research ships and instruments attached to the ocean floor measured the current’s speed and temperature. From the late 1970s onward, satellite technology—such as images showing ocean surface temperatures, measurements of ocean height, and sensors tracking ocean color—allowed scientists to map the Gulf Stream’s path and changes in real time. The launch of NASA’s TOPEX/Poseidon satellite in 1992 and later missions provided continuous data about ocean surface height, which helps scientists understand ocean circulation strength. Additionally, floating devices called drifting buoys and the Argo float network collect regular data about ocean temperature and salt levels underwater, giving scientists a detailed view of the Gulf Stream’s structure and its role in the Atlantic Meridional Overturning Circulation.
Properties
The Gulf Stream is a current that is stronger near the western side of the ocean and is mainly pushed by wind force. In 1958, oceanographer Henry Stommel observed that not much water from the Gulf of Mexico is part of the stream. The North Atlantic Current, on the other hand, is mainly pushed by thermohaline circulation. This current carries warm water northeast across the Atlantic, helping to keep Western Europe and especially Northern Europe warmer and milder than they would otherwise be.
The location of the Gulf Stream changes with the seasons, being closer to the North American coast in the summer and further away in the winter.
Formation and behaviour
A river of seawater, called the Atlantic North Equatorial Current, flows westward near the coast of Central Africa. When this current reaches the northeastern coast of South America, it splits into two branches. One branch flows into the Caribbean Sea, while the other, called the Antilles Current, moves north and east of the West Indies. These two branches come together again north of the Florida Straits.
In the tropics, trade winds blow westward, and in mid-latitudes, westerly winds blow eastward. These wind patterns create pressure on the ocean surface in the subtropical region of the North Atlantic. This pressure causes water to move toward the equator.
The movement of water is balanced by a narrow, fast-moving current along the western edge of the ocean basin. This current, called the Labrador Current, forms because of the way water moves and rotates due to wind and ocean conditions. This same process causes the Gulf Stream to bend and change direction, forming warm and cold water swirls called eddies. This process, called western intensification, makes currents along the western side of ocean basins, like the Gulf Stream, stronger than those on the eastern side.
The Gulf Stream is a powerful ocean current. It moves about 30 million cubic meters of water every second through the Florida Straits. As it moves south of Newfoundland, the flow increases to 150 million cubic meters per second. The Gulf Stream carries more water than all the rivers that flow into the Atlantic combined, which total about 0.6 million cubic meters per second. However, it is weaker than the Antarctic Circumpolar Current. Because the Gulf Stream is strong and close to the East Coast of the United States, it can affect sea levels and increase coastal erosion.
The Gulf Stream is about 100 kilometers wide and 800 to 1,200 meters deep. Water moves fastest near the surface, with speeds reaching up to 2.5 meters per second. As the Gulf Stream moves north, the warm water cools due to evaporation caused by wind. This process increases the water’s saltiness and density. When sea ice forms, salt is left behind, making the water even denser. This dense, cold water sinks in the North Atlantic, becoming part of the North Atlantic Deep Water, which flows southward. There is little seaweed in the Gulf Stream, though seaweed is found in clusters east of the current.
In April 2018, two studies published in the scientific journal Nature found that the Gulf Stream was the weakest it has been in at least 1,600 years.
Localized effects
The Gulf Stream affects the weather in Florida. The part of the Gulf Stream near Florida, called the Florida Current, keeps water temperatures above 24 °C (75 °F) in winter and often reaches 29 °C (84 °F) in summer and fall. Winds blowing from the east over this warm water carry warm air inland, making Florida's winter temperatures milder than other parts of the southeastern United States.
The Gulf Stream moves many tropical fish and sea life north along the East Coast from Florida to southeast Massachusetts during spring and summer. These fish follow the warm water and are often seen near the coast while searching for food. Examples include certain types of rays, dolphins, barracudas, and triggerfish. Near Nantucket, Massachusetts, the Gulf Stream supports a wide range of plant and animal life because it marks the farthest north where some southern plants can grow and the farthest south where some northern plants can grow. Nantucket is warmer in winter than the mainland, which is only 30 miles away to the north. North of Nantucket, the cold Labrador Current flows along the New England and eastern Canadian coasts.
The North Atlantic Current, part of the Gulf Stream, along with other warm air flows, helps keep Ireland and the western coast of Great Britain a few degrees warmer than the east. This difference is most noticeable on the western islands of Scotland. The Gulf Stream and strong winds from the west also influence weather in Norway. Northern Norway is near the Arctic, where most areas are covered in ice and snow during winter. However, Norway’s coast stays ice-free year-round because of the Gulf Stream’s warmth. This has allowed large communities, such as Tromsø, the third-largest city north of the Arctic Circle, to thrive along Norway’s northern coast. Warm weather systems carried by the Gulf Stream also reach Northern Europe, helping to keep the climate warmer on the other side of the Scandinavian Mountains.
Future predictions
Some news articles have discussed the possibility of the Gulf Stream stopping completely. The IPCC Sixth Assessment Report examined this topic and concluded that, based on computer models and scientific knowledge, the Gulf Stream will not stop in a warmer climate. Although the Gulf Stream is expected to move more slowly as the Atlantic meridional overturning circulation (AMOC) weakens, it will not stop entirely, even if the AMOC were to weaken completely. However, this slowdown could lead to important changes, such as higher sea levels along the North American coast, less rainfall in the middle latitudes, changes in rainfall patterns in Europe and the tropics, and stronger storms in the North Atlantic.
Effect on cyclone formation
The warm water and temperature differences along the edge of the Gulf Stream can make cyclones, whether tropical or not, stronger. Tropical cyclones usually form when ocean water is warmer than 26.5 °C (79.7 °F). These storms often develop over the Gulf Stream, especially in July. After forming, they move westward through the Caribbean Sea. Some storms then travel north and curve toward the eastern coast of the United States, while others move northwest and enter the Gulf of Mexico. These storms can cause strong winds and damage to coastal areas in the southeastern United States. Hurricane Sandy in 2012 was an example of a hurricane that followed the Gulf Stream and became stronger.
Strong extratropical cyclones can become much stronger along a narrow area where cold and warm air meet, which is influenced by the Gulf Stream, during colder months. Subtropical cyclones also often form near the Gulf Stream. About 75% of these systems recorded between 1951 and 2000 formed near this warm current. Activity peaks twice each year, in May and October. Cyclones that form in the open ocean near the Gulf Stream can extend as deep as 3,500 meters (11,500 feet) below the ocean's surface.
Gulf Stream rings
The Gulf Stream sometimes creates loops when a part of the current separates from the main flow and moves independently. These loops are called eddies and come in two types: cold-core eddies, which spin counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere, and warm-core eddies, which spin in the opposite direction. These eddies can carry the unique biological, chemical, and physical traits of the water where they formed to the new areas they travel to.