The world can’t really get a new ocean, of course, since Earth actually has just one interconnected ocean. Historically, though, it has been divided into four regions: Pacific, Atlantic, Arctic, and Indian.
Now you can add a fifth ocean, called the Southern Ocean.
That’s because on June 8, which happened to be World Ocean Day, the National Geographic Society announced it is “making a change to recognize the Southern Ocean as a fifth official ocean in [its] atlases and maps!”
The northern limit of the Southern Ocean — which encircles Antarctica — varies between about 50 degrees and 62 degrees south latitude. That said, National Geographic will use 60 degrees south latitude as a proxy for the Southern Ocean’s northern ecological limit.
Formally recognizing the waters around Antarctica makes sense because “scientists have known for many years that the icy waters around Antarctica form a distinct ecological region defined by ocean currents and temperatures,” National Geographic Society geographer Alex Tait explained in the announcement.
A Unique Ocean
The Pacific, Atlantic, Arctic, and Indian Oceans are defined by the continents that border them. The Southern Ocean, on the other hand, is defined by a current.
Here’s why. Scientists estimate that the Antarctic Circumpolar Current (ACC) began approximately 34 million years ago, National Geographic explains. When Antarctica separated from South America, it allowed water to circulate freely around Antarctica.
“Extending from the surface to the ocean floor, the ACC transports more water than any other ocean current,” National Geographic explains. “It pulls in waters from the Atlantic, Pacific, and Indian Oceans, helping drive a global circulation system known as the conveyor belt, which transports heat around the planet. Cold, dense water that sinks to the ocean floor off Antarctica also helps store carbon in the deep ocean. In both those ways, the Southern Ocean has a crucial impact on Earth’s climate.”
The waters south of the ACC are colder and ecologically distinct from other oceans, and they’re home to thousands of species that live nowhere else on Earth.
“The Southern Ocean encompasses unique and fragile marine ecosystems that are home to wonderful marine life such as whales, penguins, and seals,” National Geographic Explorer-in-Residence Enric Sala said.
The Need For Change
The U.S. Board of Geographic Names, created to maintain “uniform geographic name usage” through the federal government, already recognizes the Southern Ocean. A motion to recognize the Southern Ocean worldwide was proposed to the International Hydrographic Organization in 2000 — but some of the organization’s members dissented.
It is now time for a change, Tait explained, and National Geographic formally recognizing the Southern Ocean aligns with the society’s “initiative to conserve the world’s oceans, focusing public awareness onto a region in particular need of a conservation spotlight.”
“We’ve always labeled it, but we labeled it slightly differently [than other oceans],” Tait said. “This change was taking the last step and saying we want to recognize it because of its ecological separation.”
Tait also told the Washington Post that, in addition to map labeling, there’s an educational reason for recognizing the Southern Ocean as the world’s fifth ocean.“When students learn about parts of the ocean world, they learn it’s an interconnected ocean,” Tait said. “Then they learn there’s these regions called oceans that are really important, and there’s a distinct one in the icy waters around Antarctica.”
Want to experience the Southern Ocean for yourself? Be inspired by Sue Davies’s reflections on taking a solo trip to Antarctica.