National Geographic Officially Recognizes the Southern Ocean as World’s Fifth Ocean

The organization’s cartographers will now label a total of five oceans on their maps and atlases

An image showing the boundaries of the Southern Ocean surrounding Antarctica
The Southern Ocean is defined by a swift undertow called the Antarctic Circumpolar Current (ACC) that flows from West to East around Antarctica. Connormah via Wikicommons under CC BY-SA 3.0

Just in time for World Ocean Day on June 8, National Geographic cartographers declared the oceanic ring around Antarctica the world's fifth ocean.

Dubbed the Southern Ocean, the body of water's recognition by National Geographic aims to promote conservation and awareness to the fragile ecosystem where thousands of marine species like whales, seals, and penguins live, reports Sarah Gibbens for National Geographic.

The National Geographic Society has been making maps for over a century. Since the 1970s, they have had geographers oversee all modifications to every published map, reports the National Geographic. The decision to officially recognize the Southern Ocean came about after years of observing scientists and news sources using the term the Southern Ocean to describe waters near Antarctica, reports National Geographic.

"We've always labeled it, but we labeled it slightly differently [than other oceans]," Alex Tait, a National Geographic Society Geographer, tells National Geographic. "This change was taking the last step and saying we want to recognize it because of its ecological separation."

The Southern Ocean is defined by a swift undertow called the Antarctic Circumpolar Current (ACC) that flows from west to east around Antarctica, reports Andrew Chamings for SFGate. The current extends out to 60 degrees south latitude and appeared about 34 million years ago when Antarctica separated from South America, per National Geographic. The oceanic ring acts as an invisible wall that encloses Antarctica in freezing, less salty waters than northern waters. This separation makes the continent and the Southern Ocean ecologically distinct, hosting countless diverse organisms.

The U.S. Board of Geographic Names, a federal program designed in 1890 to set in place uniform geographic name usage, already recognized the arctic waters, already recognizes the Southern Ocean, reports Adam Gabbat for the Guardian. Soon after, the National Oceanic and Atmospheric Administration (NOAA) recognized the body of water as the fifth ocean in 1999 after the Board of Geographic Names approved the title, "Southern Ocean," reports Paulina Firozi for the Washington Post.

"The Southern Ocean has long been recognized by scientists, but because there was never agreement internationally, we never officially recognized it," Tait tells the National Geographic.

However, the Southern Ocean is still are not recognized by the International Hydrographic Organization (IHO). This intergovernmental organization tracks and charts global seas and oceans. The boundaries of the Southern Ocean were proposed to the IHO in 2000, but not all IHO member countries were in agreement, the Washington Post reports. Still, Tait says it was crucial to recognize the water surrounding Antarctica.

"We think it's really important from an educational standpoint, as well as from a map-labeling standpoint, to bring attention to the Southern Ocean as a fifth ocean," Tait explained to the Washington Post. "So when students learn about parts of the ocean world, they learn it's an interconnected ocean, and they learn there's these regions called oceans that are really important, and there's a distinct one in the icy waters around Antarctica."

The Southern Ocean has a substantial effect on Earth's climate. The current pulls waters from the Atlantic, Pacific, and Indian Oceans, which drives a circulation system known as the global ocean conveyor belt that transports heat around the planet, reports National Geographic. The frigid waters also pull carbon from the air down to the depths, acting as a so-called carbon sink.

Currently, researchers are studying how anthropogenic climate change is affecting Earth's newest ocean. Scientists know that Antarctica's waters are warming, and the continent's ice sheets are melting rapidly. However, it is unknown how much of these effects impact the southern continent, National Geographic reports.

Get the latest stories in your inbox every weekday.