Amanda Maxwell

Dec 17th 2021

Oceans Five With the New Southern Ocean


Reclassification of global ocean space means there are now five oceans for school kids to list. In a nod to emerging ocean technology research, National Geographic cartographers recently reclassified the band of water surrounding Antarctica as the Southern Ocean.

In redrawing the map, they hope the recognition brings climate change issues to the fore, refocusing attention on the impact global warming could have on both this pristine ecosystem and the planet as a whole.

A New Ocean for World Oceans Day 2021

This isn’t strictly a new discovery; the ocean has been hiding in plain sight since Antarctica separated from the South American continent around 34 million years ago. However, it’s a new name, with a new classification spurring recognition. The International Hydrographic Organization (IHO) charts and tracks all global seas and waters. As Smithsonian Magazine notes, the boundaries of the new ocean were proposed to the IHO back in 2000, but not all IHO members recognize this yet.

Although the U.S. National Oceanic and Atmospheric Administration (NOAA) recognized the body of water as distinct in February 2021, National Geographic chose to recognize the Southern Ocean on June 8, World Oceans Day. By redrawing maps, the hope is that the change will influence the next generations through education in school.

Ocean Technology for Discovering a New Ocean

What makes a new ocean? In the case of the Southern Ocean, it’s partly the results of new ocean technology with a heavy side order of climate change research. The new ocean is bounded by the current encircling Antarctica, the Antarctic Circumpolar Current (ACC), which flows clockwise from west to east at around 60 degrees south latitude. This ocean current boundary, rather than continental definition, makes the Southern Ocean unique, since the Indian, Pacific, Arctic and Atlantic oceans all show land boundaries.

The ACC forms a boundary, meaning it isn’t simply a southern extension of the four oceans. The new ocean is colder and slightly less salty, with the ACC transporting more water volume than any other ocean current. It’s a unique system that’s only now being recognized as essential to the pristine Antarctic ecosystem and to the planet as a whole.

Global Warming and the Southern Ocean

Defined by currents alone, the waters encircling the Antarctic are nonetheless an important planetary defense against global warming. A primary research paper published in Nature Communications charting long-term temperature changes in the first 800 meters (around 2,624 feet) of seawater showed that the ocean here was gaining heat and that human-induced warming north of the ACC exceeded its buffering capacity to absorb it.

This is important; as Encyclopedia Britannica notes, the Southern Ocean makes up one-sixteenth of the total ocean area on Earth and is an essential habitat supporting the marine food chain. As warmer water from the Indian, Pacific and Atlantic oceans flows south, cold water heading north sinks, which forms the Antarctic Convergence. This is where phytoplankton and krill — a major food source for many marine mammals and fish — flourish in abundance.

In addition to stocking the larder, the waters in the world’s newest ocean act as a heat sink. Around 35% to 43% of the global upper 2,000 meters heat gain (around 6,500 feet) was stored in the water encircling Antarctica. Furthermore, as the colder, denser water sinks to the ocean floor, it also locks down carbon away from atmospheric interaction.

The Nature Communications study, which tracked temperature changes over 25 years, revealed that warming in this area has been vastly underestimated. As the Washington Post notes, the effect of this is already being seen on the Antarctic ice shelf. This region supports a diversity of life and preserves the stability of glaciers. As warmer water flows around the margins of the continent, the ice shelf melts, leaving the glaciers unsupported. Loss of these glaciers will impact coastal communities around the planet as sea levels rise. Not only will warmer waters affect the Antarctic ecosystem, but the effects will likely be felt worldwide.

That’s why it’s important for this fifth ocean to be recognized: By spreading awareness around these changes, the world can come together and put a plan of action in place to protect these waters and ecosystems around the globe.

Check out Northrop Grumman career opportunities to see how you can participate in this fascinating time of discovery in science, technology and engineering.