By "oceanic jets", I assume you mean the Gulf Stream, the Kurushio and so forth. Those are driven by the coriolis force - the rotation of the Earth - and will not shut down from global warming. What IS at risk of shutting down from warming is the AMOC, the Atlantic Meridional Overturning Current - the current driven by cold water sinking in the North Atlantic, flowing south along the bottom and welling back to the surface at the equator when it meets its southern mirror current coming north from Antaractica. The risk to it comes from massive amounts of fresh melt water as it is a density-driven current. Stopping it will royally fuck things due to the cessation of heat transport and the loss of nutrients it provides equatorial pelagic species including the phyto- and zooplankton on which just about everything depends.
Learn more about this strong ocean current!
scijinks.gov
What causes the Gulf Stream?
The Gulf Stream is caused by a large system of circular currents and powerful winds, called an oceanic
gyre. There are five oceanic gyres on Earth. The Gulf Stream is part of the North Atlantic Subtropical Gyre.
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A gyre is a circular ocean current formed by Earth's wind patterns and the forces created by the rotation of the planet
education.nationalgeographic.org
An ocean gyre is a large system of circular ocean currents formed by global wind patterns and forces created by Earth’s rotation.
The movement of the world’s major ocean gyres helps drive the “ocean conveyor belt.” The ocean conveyor belt circulates ocean water around the entire planet. Also known as thermohaline circulation, the ocean conveyor belt is essential for regulating temperature, salinity and nutrient flow throughout the ocean.
How a Gyre Forms
Three forces cause the circulation of a gyre: global wind patterns, Earth’s rotation, and Earth’s landmasses. Wind drags on the ocean surface, causing water to move in the direction the wind is blowing.
Earth’s rotation deflects, or changes the direction of, these wind-driven currents. This deflection is a part of the Coriolis effect. The Coriolis effect shifts surface currents by angles of about 45 degrees. In the Northern Hemisphere, ocean currents are deflected to the right, in a clockwise motion. In the Southern Hemisphere, ocean currents are pushed to the left, in a counterclockwise motion.
Beneath surface currents of the gyre, the Coriolis effect results in what is called an Ekman spiral. While surface currents are deflected by about 45 degrees, each deeper layer in the water column is deflected slightly less. This results in a spiral pattern descending about 100 meters (330 feet).
Earth’s continents and other landmasses (such as islands) also influence the creation of ocean gyres. The massive South Pacific Gyre, for instance, includes hundreds of kilometers of open ocean. It is bounded only by the continents of Australia and South America, as well as the Equator and powerful Antarctic Circumpolar Current (ACC).
In contrast, the northern Indian Ocean Gyre is a much smaller ocean gyre. Unlike the South Pacific Gyre, its extent is determined largely by landmasses. The Equator forms its southern boundary, but it is bounded elsewhere by the Horn of Africa, Sri Lanka and the Indian subcontinent, and the Indonesian archipelago.
Types of Gyres
There are three major types of ocean gyres: tropical, subtropical, and subpolar.
Subpolar gyres form in the polar regions of the planet. They sit beneath an area of low atmospheric pressure. Wind drives the currents in subpolar gyres away from coastal areas. These surface currents are replaced by cold, nutrient-rich water in a process called upwelling. The Northern Hemisphere has several subpolar gyres, bounded by islands such as Iceland, Greenland, and the Aleutians; and the northern reaches of Scandinavia, Asia, and North America.
Tropical gyres form near the Equator. The Coriolis effect is not present at the Equator, and winds are the primary creators of currents. For this reason, tropical gyres tend to flow in a more east-west (instead of circular) pattern. The Indian Ocean Gyre is actually two distinct tropical gyres—the northern and southern Indian Ocean Gyres.
Most of the world’s major gyres are subtropical gyres. These form between the polar and equatorial regions of Earth. Subtropical gyres circle areas beneath regions of high atmospheric pressure. These are placid ocean areas thousands of kilometers in diameter. Unlike coastal zones, these central regions are relatively stable. The ocean water generally stays in one place while the currents of the gyre circulate around it.
Movement of Gyres
Gyres are comprised of ocean currents that link up as they follow the coastlines of Earth’s continents. Each gyre has a powerful western boundary current and a weaker eastern boundary current.
The North Atlantic Gyre begins with the northward flow of the Gulf Stream along the East Coast of the United States. The Gulf Stream is the western boundary current of the gyre. The gyre then becomes the North Atlantic Current, which flows across the North Atlantic to Europe. Still flowing in a circular pattern, the current flows south as far as the northwestern coast of Africa, where it is known as the Canary Current—the gyre’s eastern boundary current. The gyre is completed as the North Atlantic Equatorial Current crosses the Atlantic Ocean to the Caribbean Sea. This entire circle and the water within it is the North Atlantic Gyre.
Most ocean gyres are very stable and predictable. The North Atlantic Ocean Gyre always flows in a steady, clockwise path around the North Atlantic Ocean. Some gyres experience seasonal variation, however.
The Indian Ocean Gyre is a complex system of many currents extending from the eastern coast of Africa to the western coast of Australia. The northern part of the system circulates between the Horn of Africa and the Indonesian archipelago. It is sometimes called the Indian monsoon current.
The Indian monsoon current takes its name from the wind—the monsoon—that drives it. It is one of the very few currents in an ocean gyre that change direction. In the summer, the current flows clockwise, as the monsoon blows in from the southwestern Indian Ocean. In the winter, the current flows counterclockwise, as the wind blows in from the Tibetan plateau in the northeast.
The temperature in an ocean gyre depends on many factors, including the current. The Gulf Stream and summer monsoon current are warm currents. They are heated by the warm tropical waters of the Caribbean Sea (Gulf Stream) and equatorial Indian Ocean (summer monsoon current). The North Atlantic Current and winter monsoon current are cool currents. They are cooled by Arctic winds and ocean currents (North Atlantic) and the winter monsoon blowing from the icy Himalayas (winter monsoon current).
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