Gulf Stream

Ocean currents affect not only the temperature, but also the precipitation on land areas adjacent to the ocean. A cold ocean current near land causes the air just above the water to be cold, while the air above is warm. There is very little opportunity for convection, thus denying moisture to nearby land. Coastal deserts of the world usually border cold ocean currents. Contrary to this, warm ocean currents, such as Gulf Stream, bring moisture to the adjacent land areas. The Gulf Stream, together with its northern extension toward Europe, the North Atlantic Drift, is a powerful, warm, and swift Atlantic Ocean current that originates in the Gulf of Mexico, exits through the strait of Florida, and follows the eastern coastlines of the United States and Newfoundland before crossing the Atlantic Ocean. It carries a huge amount of warm water to northerly lands, which has enormous significance to inhabitants of those areas; without it, northern Europe would be much colder and drier.

At about 30 degrees W, 40 degrees N, it splits into two, with the northern stream crossing northern Europe, and the southern stream (Canary Current) recirculating off western Africa. The Gulf Stream influences the climate of the east coast of North America from Florida to Newfoundland, and the west coast of Europe. Warm water brought to Europe’s shores raises the temperature by as much as 18 degrees F (10 degrees C) in some places.

Gulf Stream Origins

The origin of the Gulf Stream is debatable. One group of scientists believes that the Gulf Stream is driven both by the rotation of the Earth and by a deep-water current called the thermohaline circulation. Another group of scientists accepts the theory propounded by Henry Stomme in 1948, that the Gulf Stream is a wind-driven phenomenon.

Heating and cooling affect its temperature and other properties, but not its basic existence or structure. Stomme theorized that as long as the sun heats the Earth and the Earth spins, there will be winds, and there will be a Gulf Stream. There is some speculation that global warming could decrease or shut down thermohaline circulation, and therefore reduce the North Atlantic Drift. The time frame in which this might happen is unclear; estimates range from a few decades to a few hundred years. This could trigger localized cooling in the north Atlantic and lead to cooling (or lesser warming) in that region, particularly affecting areas such as the Scandinavian countries and the United Kingdom. The slowdown, which climate modelers have predicted will follow global warming, has been confirmed by the most detailed study yet of ocean flow in the Atlantic. Most alarmingly, the new research reveals that a part of the current, which is usually 60 times more powerful than the Amazon River of South America, came to a temporary halt during November 2004.

Recent research has shown that changes are occurring in the Gulf Stream. According to scientists, in the absence of the Gulf Stream and its two northern branches, the North Atlantic Drift and the Canary Current, the weather in the United Kingdom could be more like that of Siberia, which lies on the same latitude. According to Peter Wadhams of the University of Cambridge, changes are occurring in the water of the Greenland Sea. Historically, large columns of very cold, dense water in the Greenland Sea, known as chimneys, sink from the surface of the ocean to about 9,000 ft. (2,743 m) below, to the seabed. As that water sinks, it interacts with the warm Gulf Stream current flowing from the south. However, the number of those chimneys, according to Wadhams, has decreased from about a dozen to just two. That is causing a weakening of the Gulf Stream, Wadham asserts, which could mean less heat reaching northern Europe. It is possible that the coastal areas of western Europe could be converted into deserts. However, proving this would require much more extensive research on changing land use patterns in coastal areas.

Harry Bryden, of the National Oceanography Centre in Southampton, presented his findings to a conference in Birmingham on rapid climate change. Bryden’s research group stunned climate researchers in 2006, with data suggesting that the flow rate of the Atlantic circulation had dropped by about 6 million tons of water a second from 1957 to 1998. If the current remained that weak, Bryden predicted, it would lead to a 1 degree C drop in the United Kingdom in the next decade. A complete shutdown would lead to a 7–11 degree F (4–6 degree C) cooling over 20 years.

Bryden’s study prompted the United Kingdom’s National Environment Research Council to set up an array of 16 submerged stations spread across the Atlantic, from Florida to northern Africa, to measure the flow rate and other variables at different depths. Data from these stations confirmed that the slowdown in 1998 was not a “freak observation,” although the current does seem to have picked up slightly since then. Richard Seager, who presented his research to the New York Academy of Sciences on “The Gulf Stream: European Climate and Abrupt Climate Change,” expressed similar views.

Seager states that a slowdown of the Gulf Stream and ocean circulation in the future, induced by freshening of the waters caused by anthropogenic climate change (via melting of glaciers and increased water vapor transport into high latitudes), or simply by warming, would introduce a modest cooling tendency.

This would leave the temperature contrast across the Atlantic unchanged. In fact, the cooling tendency would probably be overwhelmed by the direct radiatively driven warming from rising greenhouse gases.

Gulf Stream

THE GULF STREAM, a relative newcomer on the geological scene, is an odd, fast-moving circulation of warm water that travels in an unfixed position, a few hundred miles north of FLORIDA, up the east coast of the UNITED STATES to Cape Hatteras, NORTH CAROLINA, then onto Nantucket Island, before kicking eastward across the ATLANTIC OCEAN to the British Isles. In this way, the Gulf Stream, a part of the western edge of the North Atlantic circulation, acts as a boundary that prevents the warm water of the SARGASSO SEA from overflowing the colder, denser waters on the inshore side.

The Gulf Stream is one of the strongest and most extensive known currents in the world, and it is separated from the United States by a narrow strip of cold water. The Gulf Stream, which can be as much as 50 mi (80 km) wide and 1,300 ft (400 mi) deep, is caused by the northeast and southeast trade winds on the surface of the water and the equatorial currents that meet in the region of the windward islands of the CARIBBEAN SEA.

The Gulf Stream’s rival, the KUROSHIO CURRENT, located along the western edge of the PACIFIC OCEAN and the coast of JAPAN, is part of a transpacific system that connects the North Pacific, California, and equatorial currents. The Gulf Stream triples in volume and is strengthened by the waters from the Florida Straits, by way of the Florida Current, and by currents coming from the northern and eastern coast of PUERTO RICO and the BAHAMAS. It can travel more than 60 mi (96 km) a day.

The Gulf Stream, first mapped by Benjamin Franklin and his American whaling captain cousin Timothy Folger, early pioneers in using temperature in an attempt to define its boundaries, maintains its dimensions for nearly 1,000 mi (1,610 km) up the East Coast of the United States. Franklin, using observations of current speed in the region of the Gulf Stream and plotting them on a chart, was able to draw a river traversing the Atlantic Ocean with speeds ranging from 4 to 2 knots.

The strong carry power of the Gulf Stream’s warm equatorial layers of water has a notable, almost direct effect on the climate in various parts of the Earth. As the Gulf Stream moves pass Cape Hatteras, NORTH CAROLINA, it begins to flow away from the East Coast of the United States. The altered flow of the Gulf Stream, known as meanders or eddies, separates the cold slope water to the north from warm Sargasso Sea water to the south. As the Gulf Stream flows into deeper water, it carries warm water to the North Atlantic region, as it enters the Norwegian Sea between the FAROE ISLANDS and Great Britain. Thus, the Gulf Stream, which bathes northwest Europe with warmer water and wind currents, is largely believed to be the reason for mild European climate.

Too warm to encourage the kind of fish that are the main catch of North Atlantic waters, the Gulf Stream does bring well-developed specimens of tropical fish, like the Portuguese man-of-war jellyfish, much farther to north than they would normally venture. In addition, there are two particular species of plant (the double coconut tree indigenous to JAMAICA) and animal life (the freshwater eels of Europe) that are carried for thousands of miles by the Gulf Stream surface transport

system to the shores of IRELAND and Scotland.

Because the current patterns of the oceans has been the same as it is today throughout historical time, it becomes easy to understand that the Gulf Stream played an important role in the history of the New World. Indeed, it was during the early days of discovery of the West Indies, including the large islands of CUBA, HAITI, and Jamaica, that the Gulf Stream was first reported by Juan Ponce de Leon. During the American colonial period, the principal ocean routes for New England traders of rum and sugar and species—the direct northerly route influenced by clockwise circulation of the North Atlantic and the southwest route influenced by the clockwise currents northward past Florida—

played their part in the development of North America. Through the advent of frequent voyaging between the Old World and the New, the Gulf Stream came into its own as the most comfortable homeward route from the West Indies to Europe.

As we now understand, the Gulf Stream can be regarded as merely the outer edge of a general rotation of the surface waters of the North Atlantic. As such, it deserves it popularity with mankind because, in general, it has a benign influence on man’s affairs. The Gulf Stream has attracted the attention of many investigators and is probably the most studied example of ocean circulation. Although it can be questioned whether the Gulf Stream should be considered as a separate entity or regarded as the outer edge of the North Atlantic circulation, it is still one of the largest and fastest of the water circulation of the seas. It has always played an important role in the lives of people who live on the land that borders the North Atlantic.