The Southern Ocean is the new fifth ocean of our planet

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Many of us, especially those who graduated from high school in the 2000s and earlier, do not realize that a new ocean has appeared on the geographical map of the world. This is because only in 2000, the member states of the International Hydrographic Organization decided to allocate one more ocean in the world ocean – the Southern Ocean.

The Southern Ocean is an independent ocean that combines the southern parts of the Atlantic, Indian and Pacific Oceans. This new fifth ocean is already appearing on many physical maps and globes.

The Southern Ocean is also known as the Antarctic Ocean as it surrounds Antarctica. The Antarctic Ocean does not have a northern border clearly defined by islands and continents, and its area can be determined by oceanological features: as a line of convergence of cold Antarctic currents with warmer waters of the three oceans. But such a border constantly changes its position and depends on the season, so it is inconvenient for practical purposes.

The Southern Ocean is the new fifth ocean of our planet

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The Southern Ocean is the fifth largest ocean, with an area of ​​20,327 million km². As for the boundaries of the new ocean, it is generally accepted that it is located between the coast of Antarctica and the 60th parallel of south latitude.

The Southern Ocean is the new fifth ocean of our planet

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The New Ocean is also called the Australian Ocean – the Australian government considers the Southern Ocean to be waters located immediately south of the Australian continent. Accordingly, many maps of Australia show that the Southern Ocean lies immediately south of Australia.

The Southern Ocean is the new fifth ocean of our planet

wikipedia.org

The Southern Ocean is the youngest of the oceans, its age is estimated at 30 million years. Its appearance is due to the separation of South America and Antarctica. At the same time, a strait arose, which gave rise to the West Wind Current (or the Antarctic Circumpolar Current).

Next, we propose to consider an interesting history of its display on world maps.

 

History of the Southern Ocean

The term "Southern Ocean" appeared many times as early as the 18th century, when systematic exploration of the region began.

In the first edition of The Limits of Oceans and Seas in 1928, the Southern Ocean was delineated by terrestrial boundaries: from Antarctica in the south to South America, Africa, Australia and Broughton Island (New Zealand) in the north.

The northern limits of the Southern Ocean were moved south in the International Hydrographic Organization's 1937 second edition of The Limits of Oceans and Seas. Since this edition, most of the northern boundary of the ocean has ceased to adjoin the land. This had its own explanation: in its southern part, the boundaries between the three oceans are very arbitrary, at the same time, the waters adjacent to Antarctica have their own specifics, and are also united by the Antarctic circumpolar current.

The Southern Ocean disappeared altogether in 1953 in the third edition of The Limits of the Oceans and Seas, and the publication note says:

Antarctica or the Southern Ocean have been excluded from this publication because most opinions received since the 2nd edition in 1937 have been that there is no real justification for applying the term "ocean" to this body of water, the northern limits of which difficult to determine due to their seasonal variations. Therefore, the boundaries of the Atlantic, Pacific and Indian Oceans were extended south to Antarctica.

Therefore, hydrographic offices that issue separate publications relating to this area must determine their own northern boundaries (for example, in the UK, the 55th parallel of south latitude was used).

In 2000, the International Hydrographic Organization (IHO) decided to divide the World Ocean into five oceans, highlighting the Southern Ocean, but this decision was never ratified. This is because to make this decision, the IHO decided to conduct a poll, out of 68 countries, only 28 agreed to vote. All voters (with the exception of Argentina) agreed to redefine the ocean, reflecting the importance that oceanographers attach to ocean currents. The proposal for the name "Southern Ocean" received only 18 votes, ahead of the alternative option "Antarctic Ocean". Half of the votes supported the definition of the northern boundary of the Southern Ocean at 60 south latitude, the remaining 14 votes were cast for other definitions, mainly at 50 south latitude, although some – no further than 35 south latitude.

A draft fourth edition of Limits of the Oceans and Seas was circulated to IHO member countries in August 2002 (sometimes referred to as the "2000 edition" because it summarizes the results achieved in 2000). It has yet to be published due to the disagreement of some countries regarding the borders and the name of the new ocean.

We have displayed this entire history of the emergence of the Southern Ocean on the following map (click on the image to enlarge).

Satellite map showing how the Southern Ocean delimitation moved southward from the ocean's initial formal approval in 1928 until the (rough) International Hydrographic Organization delimitation in 2002.

Click on image to enlarge | wikipedia.org

 

Examples of the use of the term "Southern Ocean" around the world

Although the Southern Ocean has not been officially approved by all IHO member countries, the definition of the Southern Ocean in the fourth edition of the Limits of the Oceans and Seas is already used by many countries, scientists and organizations around the world. So the name "Southern Ocean" is used by the CIA World Book of Facts (USA), Merriam-Webster (an American company, publisher of reference books and lexical dictionaries), Wikipedia, and even some oceanographers at the IHO.

The hydrographic offices of some countries have defined their own boundaries for the new ocean. For example, Great Britain used the 55th parallel south latitude. Other organizations prefer more northerly limits for the Southern Ocean.

Another interesting example is the Encyclopædia Britannica, the oldest English-language universal encyclopedia. The Encyclopædia Britannica describes the Southern Ocean as extending as far north as South America, and gives great importance to the Antarctic Convergence, but its description of the Indian Ocean contradicts this by describing the Indian Ocean. Ocean as extending south to Antarctica.

Other sources such as the National Geographic Society (one of the largest scientific and educational organizations in the US) show the Atlantic, Pacific and Indian Oceans as extending to Antarctica on their maps, although many articles on the National Geographic website have begun to refer to the Southern Ocean.

 

National Geographic acknowledges the existence of a fifth ocean

The scientific debate that has been going on for decades has come to an end. Now the Southern Ocean will be marked on maps and infographics from National Geographic.

On World Oceans Day 2021 – June 8 – Nat Geo cartographers said that the fast current circling Antarctica keeps the waters there distinct and worthy of their own name – the Southern Ocean.

National Geographic has been producing maps since 1915 and only four oceans are included: the Atlantic, the Pacific, the Indian, and the Arctic. Since June 8, 2021, National Geographic cartographers have recognized the fifth – the Southern Ocean.

"The Southern Ocean has long been recognized by scientists, but since there was no international agreement, we did not officially recognize it," – National Geographic Society geographer Alex Tait (Alex Tait).

Over the years, experts have debated whether the waters around Antarctica have unique characteristics to deserve their own name, or if they are simply cold extensions of neighboring oceans.

Alex Tate characterizes these discussions as "a kind of geographic bore". He and the National Geographic Society's Charting Policy Committee have been considering this change for years, seeing how scientists and the press increasingly use the term "Southern Ocean".

“We always labeled it, but we labeled it a little differently [than other oceans]. This change was the final step and a statement that we want to recognize it because of its environmental separation,” says Tate.

For nautical names, National Geographic is guided by the International Hydrographic Organization (IHO). Back in 1937, the IHO recognized the Southern Ocean, but in 1953 it canceled this decision under pressure from the scientific community, which could not come to a consensus.

The U.S. Board of Geographic Names has used the name since 1999, and in February 2021, the National Oceanic and Atmospheric Administration (NOAA) officially recognized the Southern Ocean as a separate region. In turn, the National Geographic Mapping Policy Committee has observed how the frequency of use of the term by scientists and the press is growing.

The Southern Ocean includes most of the waters surrounding Antarctica up to 60 degrees south latitude, with the exception of the Drake Passage and the Scotia Sea. While other oceans are defined by the continents that surround them, the Southern Ocean is defined by current. We will tell you more about this later.

The Southern Ocean is the new fifth ocean of our planet

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Scientists estimate that the Antarctic Circumpolar Current emerged approximately 34 million years ago when Antarctica separated from South America. This ensured an unobstructed flow of water around the "bottom of the Earth".

The Antarctic Circumpolar Current (ACC) flows from west to east around Antarctica in a wide, oscillating band roughly centered around 60°S, a line now defined as the northern boundary of the Southern Ocean. Inside the ACC, the water is colder and less saline than the ocean waters to the north.

Passing from the surface to the bottom of the ocean, the ACC carries more water than any other ocean current. It draws in water from the Atlantic, Pacific and Indian oceans, helping to drive the global circulation system known as the conveyor belt that transports heat around the planet. The cold, dense water that sinks to the ocean floor near Antarctica also contributes to the accumulation of carbon in the deep ocean. In both cases, the Southern Ocean has a decisive influence on the Earth's climate.

Scientists are currently studying how human-induced climate change is affecting the Southern Ocean. Scientists have found that ocean water passing through the ACC heats up, but it is not clear how much this affects Antarctica. Some of the continent's fastest-melting ice sheets are located exactly where the ACC is closest to land.

The recognition of the Southern Ocean aligns with the Society for the Conservation of the World Ocean's initiative to focus on a region that is in particular need of conservation action.

For now, by enclosing cold southern waters, ACC is helping to keep Antarctica cold and the Southern Ocean ecologically distinct. Thousands of species of marine life live only there and nowhere else.

“The Southern Ocean encompasses unique and fragile marine ecosystems that are home to beautiful marine life such as whales, penguins and seals,” said Enric Sala, researcher and National Geographic Explorer staff conservationist.

By drawing attention to the Southern Ocean, the National Geographic Society hopes to contribute to its conservation.

“Many countries around the world support the protection of certain areas of the Southern Ocean from commercial fishing,” says Sala.

 

Interesting facts about the Southern Ocean

  • The greatest depth of the ocean lies in the South Sandwich Trench and is 8264 meters.
  • The average depth of the Southern Ocean is 3270 meters.
  • Of all the five oceans, this is the smallest, with an area of ​​20,327 million km².
  • The length of the coastline is 17968 km.
  • The salinity of the waters is only about 35 ‰ as a result of their desalination by iceberg melt waters, a large number of which also float in the waters of the Southern Ocean both in winter and in summer.
  • Off the coast of Antarctica, 13 seas are distinguished, 12 of them (except for the Scotia Sea) are part of the new ocean and are closely adjacent to the shores of the icy continent.

The Southern Ocean is the new fifth ocean of our planet

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