South Australia now sits on the Indian Ocean, according to National Geographic

National Geographic has defined the boundaries of the Southern Ocean … and it’s nowhere near us.

Next time you’re standing on a clifftop gazing out over the mighty Southern Ocean, stop and ask yourself: “Am I really gazing out over the Southern Ocean?”.

No, it’s not an exercise in philosophical navel-gazing, merely an acknowledgment of the latest chapter in the century-old debate surrounding the boundaries of the frigid sea surrounding Antarctica.

Ask the cartographers and geographers at National Geographic and they will tell you that from June 8, World Oceans Day, the Southern Ocean is officially defined as the waters south of 60 degrees – about 2500km south of Adelaide.

The announcement from the respected society means that, as far as their maps are concerned, the Southern Ocean is now the world’s fifth ocean, joining the Indian, Atlantic, Pacific and Arctic.

“The Southern Ocean has long been recognised by scientists, but because there was never agreement internationally, we never officially recognised it,” National Geographic Society geographer Alex Tait says.

Geographers debated whether the waters around Antarctica had enough unique characteristics to deserve their own name, or whether they were simply cold, southern extensions of the Pacific, Atlantic, and Indian oceans.

“It’s sort of geographic nerdiness in some ways,” Mr Tait says.

He and the National Geographic Society’s map policy committee had been considering the change for years, watching as scientists and the media increasingly used the term Southern Ocean.

The boundaries of the Southern Ocean, as defined by National Geographic

“We’ve always labelled it, but we labelled it slightly differently (than other oceans),” Mr Tait says. “This change was taking the last step and saying we want to recognise it because of its ecological separation.”

What does this mean for South Australia? Well not that much, beyond getting used to the fact the state sits – at least if we take National Geographic’s word for it – in the Indian Ocean.

From a tourism marketing point of view, this is an issue. The Southern Ocean Lodge – planning to rebuild after the devastating Kangaroo Island bushfires – for example, sounds far more rugged and romantic than the Indian Ocean Lodge.

But before we go renaming lodges, walking trails and B&Bs, Flinders University historian Dr Alessandro Antonello says we should realise the boundaries of the Southern Ocean have long been debated and the fact National Geographic has planted a flag on the hill doesn’t mean the debate is over.

Indeed, the senior research fellow and Antarctic expert says the ocean has even come in and out of existence like a marine version of “planet” Pluto.

“National Geographic is catching up here, in a way, and it doesn’t have any real power over the world’s maps, although they do make some of the most beautiful maps,” Dr Antonello says.

“There’s a bit of a tension because here in Australia we generally refer to the ocean south of our country as the Southern Ocean. The problem is that scientists, since about the 1930s, have understood that the ocean that surrounds Antarctica is one entity, both physically and biologically.”

However, Dr Antonello says National Geographic’s attempt to define the Southern Ocean by drawing a ring at 60 degrees south was a little too convenient.

“It (the Southern Ocean) is very distinct physically – there’s a line called the Antarctic Convergence where the cold water very quickly becomes warmer water to its north,” he says.

“The problem is how do you map that? It’s a meandering line that changes very slightly from season to season.”

Dr Antonello says scientists – since the 1930s – had a good sense that the Southern Ocean was a distinct ocean but nobody could quite agree on how to best represent that on a map.

“That’s where the International Hydrographic Organisation comes in, and several times in the 20th century the IHO has both put the Southern Ocean on the map and taken it off,” he says.

“Some of the definitions before World War II have a huge Southern Ocean, and would include the waters just below Australia. In 1953, the IHO removed the Southern Ocean completely from the map. The IHO tried to review the 1953 document in 2000 and failed.”

So where does that leave South Australia? Are we part of the Southern Ocean, or are we an outpost in the eastern part of the Indian Ocean?

Big ocean swells in the Southern Ocean. Or the Indian.

“That’s a really good question,” Dr Antonello says. “I suppose culturally we’ll always think of it as the Southern Ocean, but I think if we call things by a name that matches its physical reality then we might have a better sense of what the ocean actually is.

“If we think about The Bight as being part of the Indian Ocean then that might connect us more clearly to the currents and movements of the Indian Ocean.”

While National Geographic may have determined the Southern Ocean starts at 60 degrees south, which is very convenient for mapping purposes, it’s actually the Antarctic circumpolar current that defines its characteristics.

The other oceans of the globe are defined by the huge continents that fence them in, making their mapping a much more straightforward process.

Scientists believe the Antarctic circumpolar current began about 34 million years ago when South America finally separated from Antarctica, allowing the sea to flow unimpeded by land around the lower parts of the globe.

And while we may believe the seas have always been thus, there is an important geopolitical element to the naming of bodies of water.

The Sea of Japan, for example, is known as the East Sea in South Korea, while the South China Sea has several names, depending on which country is driving the narrative.

“It is important to note it’s a map policy, not a policy about Nat Geo’s position on (geopolitical) disputes,” Mr Tait says.

National Geographic maps show, for example, that the UK controls the Falkland Islands, even though Argentina claims them, too.

In disputed areas, Mr Tait works with a team of geographers and editors to determine what most accurately represents a given region.

In this case, Mr Tait says, he hoped the inclusion of the Southern Ocean would inspire generations of school students to consider the importance of our Antarctic seas.

“I think one of the biggest impacts is through education,” he says.

“Students learn information about the ocean world through what oceans you’re studying.

“If you don’t include the Southern Ocean then you don’t learn the specifics of it and how important it is.”