National Geographic’s controversial choice to declare a fifth ocean, explained

Some scientific organisations have recognised the Southern Ocean around Antarctica since the 1930s, but there’s still disagreement about what the world maps should say

Oceans, I hate to tell you, are a social construct. There is but one mega-ocean on our blue marble, covering 71 per cent of the surface of the Earth.

However, if your mind is still caged in the thinking of the man, and you subscribe to the artificial boundaries outlined on these things called “maps,” there’s some exciting news for you: there’s a fifth ocean, the snappily named Southern, joining the global family alongside the Atlantic, Pacific, Indian, and Arctic Oceans. According to some people, that is.

There’s a fifth ocean now? Kind of.

This Tuesday, on World Oceans Day no less, the venerable geographic institution and magazine National Geographic decided to recognize a fifth ocean, the Southern Ocean, on its maps for the first time in its more than 100 year history.

So where is it?

The Southern Ocean is a more than 7.8 million square mile blob of water, occupying more than twice the area of the US, that surrounds Antarctica.

Why would they do such a thing, and why now?

“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 magazine. “It’s sort of geographic nerdiness in some ways.”

But they’ve got a point, these map nerds.

Most oceans are defined by the continents that surround them, but this one has genuine natural boundaries within the water itself.

For one thing, there’s the Antarctic Circumpolar Current (ACC), which has been ferrying water around the southern continent in a circle for the last 24 million years. The waters within this circle are distinct as well, tending to be colder and less salty than in other places.

There are also thousands of species that can only be found in the Southern Ocean, and others who use it as an important stop on global migration journeys, like whales.

Then there’s the vital matter of climate crisis

National Geographic says the decision will help shine a light on the many ways global heating is affecting the region, from melting sea ice, to warming the waters of the ACC, a worrying trend in one of the crucial global mechanisms that circulates and stores heat and carbon.

Antarctic ice is melting six times faster than it was in the 1990s.

But not everyone is on board with the change.

All the way back in 1937, the International Hydrographic Organization, which works with the UN to standardise place names, recognised the Southern Ocean as its own entity, but repealed the change in 1953 amid disagreement over its accuracy.

Others, like the US Board on Geographic names have used the term since 1999, while the American National Oceanic and Atmospheric Administration (NOAA) joined them in this understanding this February. Australia and New Zealand also argue there’s a Southern Ocean.

Regardless of one’s position, people hope it brings more attention to a vital region of the Earth

Here’s how NOAA marine scientist Seth Sykora-Bodie put it in a recent article:

“Anyone who has been there will struggle to explain what’s so mesmerizing about it, but they’ll all agree that the glaciers are bluer, the air colder, the mountains more intimidating, and the landscapes more captivating than anywhere else you can go,” he said.