On World Ocean’s Day last Tuesday, the National Geographic Society officially recognized the Southern Ocean as the fifth ocean in the world, joining the Arctic, Atlantic, Indian, and Pacific.
“The Southern Ocean has long been recognized by scientists, but because there was never agreement internationally, we never officially recognized it,” National Geographic Society Geographer Alex Tait told the society’s eponymous monthly magazine.
The Southern Ocean is the body of water surrounding the continent of Antarctica. It extends in a ring from Antarctica’s coastline to 60 degrees south latitude, excluding the Drake Passage and Scotia Sea. Unlike the four other oceans that are defined by the continents that fence them in, the Southern Ocean ― whose area is slightly bigger than twice the size of the U.S. ― is defined by a current called the Antarctic Circumpolar Current (ACC).
Established roughly 34 million years ago when Antarctica separated from South America, the ACC flows from west to east around Antarctica in a broad fluctuating band roughly centered around a latitude of 60 degrees south — the line that is now defined as the northern boundary of the Southern Ocean.
ANNOUNCING: Today on #WorldOceansDay, National Geographic has updated its Map Policy to recognize the Earth’s fifth ocean: the Southern Ocean.
Follow this thread to dive deep into why. 🌊 pic.twitter.com/u6KsQAtGDD
— National Geographic Society (@InsideNatGeo) June 8, 2021
The International Hydrographic Organization, which works with the United Nations Group of Experts on Geographical Names to standardize names on an international scale, recognized the Southern Ocean in its 1937 guidelines but repealed that designation in 1953 and has yet to reinstate it.
The U.S. Board on Geographic Names, meanwhile, has used the Southern Ocean name since 1999, and the National Oceanic and Atmospheric Administration recognized it in February as distinct.
Aside from the fact that the waters around Antarctica had enough unique characteristics to deserve their own name, the addition of the Southern Ocean to the world map is part of the society’s efforts to conserve the world oceans.
National Geographic Explorer in Residence Enric Sala told the magazine that the Southern Ocean “encompasses unique and fragile marine ecosystems that are home to wonderful marine life such as whales, penguins, and seals.” Thousands of species are endemic to the Southern Ocean, and according to the magazine, impacts of fishing on the region have been felt for decades.
Scientists have also learned that ocean water moving through the ACC is warming. Though it’s unclear how much this is impacting Antarctica, the world’s largest iceberg, which was more than three times the size of Los Angeles, broke off from Antarctica in May. In February, another iceberg larger than New York City broke off.
However, Tait told the magazine that the biggest impact from the society’s decision to add the Southern Ocean to the world map will be on education. “Students learn information about the ocean world through what oceans you’re studying,” he said. “If you don’t include the Southern Ocean then you don’t learn the specifics of it and how important it is.”