Nat Geo recognizes Southern Ocean as 5th official ocean

National Geographic has labeled the Southern Ocean as the world’s fifth official ocean in light of a growing number of scientists and researchers recognizing the waters swirling around Antarctica as a distinct area. 

The environmental news network announced the decision Tuesday in honor of World Oceans Day, adding the Southern Ocean to the four bodies of water already internationally recognized: Atlantic, Pacific, Indian and Arctic. 

National Geographic Society Geographer Alex Tait said in a statement, “The Southern Ocean has long been recognized by scientists, but because there was never agreement internationally, we never officially recognized it.” 

Tait told NPR’s “All Things Considered” this week that while the four other oceans are “defined primarily by land masses,” National Geographic decided to add the Southern Ocean as the fifth one “because it’s so unique and because we want to bring attention to all areas of the ocean.”

National Geographic noted Tuesday that the Southern Ocean can be differentiated based on its current, known as the Antarctic Circumpolar Current (ACC), which was established 34 million years ago when Antarctica separated from South America. 

Waters within the ACC are known to be colder and slightly less salty than ocean waters to the north, according to National Geographic. 

The ACC is also responsible for helping to regulate the Earth’s climate, with scientists currently studying how human-induced climate change may be altering the characteristics of the Southern Ocean. 

While the U.S. Board on Geographic Names has used the Southern Ocean label since 1999, the National Oceanic and Atmospheric Administration (NOAA) did not officially label the waters as distinct until February of this year. 

In a statement on its website, NOAA called the Southern Ocean the “‘newest’ named ocean,” defining it as the “body of water extending from the coast of Antarctica to the line of latitude at 60 degrees South.” 

However, NOAA noted at the time that not all countries agree on the exact boundaries of the Southern Ocean, and the proposed area has yet to be ratified by the International Hydrographic Organization.