The majority of the Gulf Stream is classified as a western boundary current. This means that it is a current with behavior determined by the presence of a coastline - in this case the eastern United States and Canada - and is found on the western edge of an oceanic basin. Western boundary currents are normally very warm, deep, and narrow currents that carry water from the tropics to the poles.
The Gulf Stream was first discovered in 1513 by the Spanish explorer Juan Ponce de Leon and was then used extensively by Spanish ships as they travelled from the Caribbean to Spain. In 1786, Benjamin Franklin mapped the current, further increasing its usage.
Path of the Gulf StreamToday, it is understood that the waters feeding into the Gulf Stream begin flowing off the west coast of Northern Africa (map). There, the Atlantic North Equatorial Current flows from that continent across the Atlantic Ocean. Once the current reaches eastern South America, it splits into two currents, one of which is the Antilles Current. These currents are then funneled through the islands of the Caribbean and through the Yucatan Channel between Mexico and Cuba.
Because these areas are often very narrow, the current is able to compress and gather strength. As it does so, it begins circulating in the Gulf of Mexico’s warm waters. It is here that the Gulf Stream becomes officially visible on satellite images so it is said that the current originates in this area.
Once it gains enough strength after circulating in the Gulf of Mexico, the Gulf Stream then moves east, rejoins the Antilles Current, and exits the area through the Straits of Florida. Here, the Gulf Stream is a powerful underwater river that transports water at a rate of 30 million cubic meters per second (or 30 Sverdrups). It then flows parallel to the east coast of the United States and later flows into the open ocean near Cape Hatteras but continues moving north. While flowing in this deeper ocean water, the Gulf Stream is its most powerful (at about 150 Sverdrups), forms large meanders, and splits into several currents, the largest of which is the North Atlantic Current.
The North Atlantic Current then flows further north and feeds the Norwegian Current and moves the relatively warm water along the west coast of Europe. The rest of the Gulf Stream flows into the Canary Current which moves along the eastern side of the Atlantic Ocean and back south to the equator.
Causes of the Gulf StreamThe Gulf Stream, like all other ocean currents is mainly caused by wind as it creates friction when moving over the water. This friction then forces the water to move in the same direction. Because it is a western boundary current, the presence of land along the Gulf Stream’s edges also aids in its movement.
The northern branch of the Gulf Stream, the North Atlantic Current, is deeper and is caused by thermohaline circulation resulting from density differences in the water.
Impacts of the Gulf StreamBecause ocean currents circulate water of different temperatures all over the globe, they often have a significant impact on the world’s climate and weather patterns. The Gulf Stream is one of the most important currents in this regard since it gathers all of its water from the warm tropical waters of the Caribbean and the Gulf of Mexico. As such, it keeps sea surface temperatures warm, causing the areas around it to be warm and more hospitable. Florida and much of the Southeastern United States for instance is mild all year round.
The greatest impact the Gulf Stream has on climate is found in Europe. Since it flows into the North Atlantic Current, it too is warmed (though at this latitude the sea surface temperatures are cooled considerably), and it is believed that it helps keep places like Ireland and England much warmer than they would otherwise be at such a high latitude. For example, the average low in London in December is 42°F (5°C) while in St. John’s, Newfoundland, the average is 27°F (-3°C). The Gulf Stream and its warm winds are also responsible for keeping northern Norway’s coast free of ice and snow.
As well as keeping many places mild, the Gulf Stream’s warm sea surface temperatures also aid in the formation and strengthening of many of the hurricanes that move through the Gulf of Mexico. Additionally, the Gulf Stream is important to the distribution of wildlife in the Atlantic. The waters off of Nantucket, Massachusetts for example are incredibly biodiverse because the presence of the Gulf Stream makes it the northern limit for southern species varieties and the southern limit for northern species.
The Future of the Gulf StreamAlthough there are no definitive answers, it is believed that the Gulf Stream could be in the future or is already being impacted by global warming and the melting of glaciers. Some studies suggest that with the melting of ice in places like Greenland, cold, dense water will flow into the ocean and disrupt the flow of the Gulf Stream and other currents that are part of the Global Conveyor Belt. If this were to happen, weather patterns worldwide could change.
Recently, there has been evidence that the Gulf Stream is weakening and slowing and there is growing concern about what impacts such a change would have on the world’s climate. Some reports suggest that without the Gulf Stream, temperatures in England and northwestern Europe could drop by 4-6°C.
These are the most dramatic of the predictions for the future of the Gulf Stream but they, as well as today’s climate patterns surrounding the current, show its importance to life in many places around the world.