Current Affairs

National Geographic officially recognizes the Southern Ocean as World’s Fifth Ocean

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  • Published
    16th Jun, 2021
  • Context

    The Earth has finally attained popular recognition for its fifth ocean, with a decision by the National Geographic Society to add the Southern Ocean around Antarctica to the four it recognizes already: the Atlantic, Pacific, Indian and Arctic oceans.

  • Background

    • The National Geographic Society has been making maps for over a century.
    • Since the 1970s, they have had geographers oversee all modifications to every published map.
    • The decision to officially recognize the Southern Ocean came about after years of observing scientists and news sources using the term the Southern Ocean to describe waters near Antarctica.
    • Although the designation of the frigid waters around the icy southern continent as a separate ocean has kicked around for almost 100 years and is widely used by scientists, until now it has not had popular backing.
    • But on June 8 (World Oceans Day), the society announced it would henceforth be labeling the Southern Ocean as the fifth ocean on its maps of our planet.
      • World Ocean Day 2021 Theme: “The Ocean: Life and Livelihoods”. The theme is especially relevant in the lead-up to the UN Decade of Ocean Science for Sustainable Development, which will run from 2021 to 2030.
        • The decade is aimed at strengthening international cooperation to develop scientific research and innovative technologies that are capable of connecting ocean science with the needs of modern society.
  • Analysis

    What exactly is an ocean?

    • Exactly what constitutes an ocean is not agreed, other than that they are the largest bodies of water.
    • A common definition split the global ocean into four or five parts, according to the continents that surrounded them.

    Origin of the term

    • The original "ocean" on Earth was, in fact, a river — named by the ancient Greeks after the titan Oceanus, a river god who was the son of Uranus and Gaia and the brother and husband of Tethys, the goddess of the primal waters that nourished the Earth.
    • This river "Ocean" was originally thought to encircle the world, which the early Greeks imagined ended somewhere just west of Europe and east of Asia.
    • Eventually, the term would become used to describe the different parts of the global ocean.
    • The related term "Seven Seas," meanwhile, is much older than many modern oceans.
    • No one knows where the concept originated, but the term appears in the ancient writings of the Greeks, Romans, Arabs, Hindus, Persians and Chinese, although it often described entirely different seas — some of them mythical — for different people. 
    • According to the World Atlas website, the Seven Seas today are considered the seven largest oceanic bodies of water: the Arctic, North Atlantic, South Atlantic, Indian, North Pacific, South Pacific, and Southern or Antarctic Ocean.
  • About Southern Ocean

    • The Southern Ocean stretches from Antarctica's coastline to 60 degrees south latitude, excluding the Drake Passage and the Scotia Sea.
    • The newest body of water makes it the second-smallest, after the Arctic.
    • Southern Ocean is defined not by the continents that surround it, but by the Antarctic Circumpolar Current (ACC) that flows from west to east.
    • The current was created 34 million years ago when the continent of Antarctica separated from South America, allowing water to flow unimpeded around the "bottom" of the world.
    • Today, the ACC flows through all waters that surround Antarctica until about 60 degrees south, except for the Drake Passage and the Scotia Sea, which are both roughly between South America's Cape Horn and the Antarctic Peninsula.
    • The waters of the ACC — and therefore most of the Southern Ocean — are colder and slightly less salty than the ocean waters to the north.

    Antarctic Circumpolar Current (ACC)

    • The Antarctic Circumpolar Current, or ACC, is the strongest ocean current on our planet.
    • It extends from the sea surface to the bottom of the ocean, and encircles Antarctica.
    • The ACC carries an estimated 165 million to 182 million cubic metres of water every second (a unit also called a “Sverdrup”) from west to east, more than 100 times the flow of all the rivers on Earth.
    • It provides the main connection between the Indian, Pacific and Atlantic Oceans.
    • The tightest geographical constriction through which the current flows is Drake Passage, where only 800 km separates South America from Antarctica.

    How ACC is created?

    • The ACC is created by the combined effects of strong westerly winds across the Southern Ocean, and the big change in surface temperatures between the Equator and the poles.
    • Ocean density increases as water gets colder and as it gets more salty.
    • The warm, salty surface waters of the subtropics are much lighter than the cold, fresher waters close to Antarctica.
    • The depth of constant density levels slopes up towards Antarctica.
    • The westerly winds make this slope steeper, and the ACC rides eastward along it, faster where the slope is steeper, and weaker where it’s flatter.

  • How the fifth ocean is distinct?

    • The oceanic ring acts as an invisible wall that encloses Antarctica in freezing, less salty waters than northern waters.
    • This separation makes the continent and the Southern Ocean ecologically distinct, hosting countless diverse organisms.
  • How Southern Ocean impacts Earth’s climate?

    • The Southern Ocean has a substantial effect on Earth's climate.
    • The ACC pulls waters from the Atlantic, Pacific, and Indian Oceans, which drives a circulation system known as the global ocean conveyor beltthat transports heat around the planet.
    • The frigid waters also pull carbon from the air down to the depths, acting as a so-called carbon sink.
  • What are the reasons behind this recognition?

    • Dubbed the Southern Ocean, the body of water's recognition by National Geographic aims to promote conservation and awareness to the fragile ecosystem where thousands of marine species like whales, seals, and penguins live.

    Recognition from International Hydrographic Organization (IHO)

    • However, the Southern Ocean is still are not recognized by the International Hydrographic Organization (IHO).
    • The boundaries of the Southern Ocean were proposed to the IHO in 2000, but not all IHO member countries were in agreement.
      • IHO tracks and charts global seas and oceans.
      • Established in: 1921
  • Conclusion

    Separately identifying the Southern Ocean will highlight the region's unique and urgent conservation needs and also contribute to other educational and scientific research efforts.