The Gerasch Strait is located off the west coast of the Antarctic Peninsula, in a large area of waters around Antarctica; this area has been reclassified by National Geographic cartographers as the Southern Ocean. The Gerass Strait was once considered part of the Pacific Ocean. Photo by JASPER DOEST, NAT GEO IMAGE COLLECTION
Written by: SARAH GIBBENS
The Southern Ocean, as anyone familiar with it, knows that this body of water that surrounds Antarctica is very unique.
"It's hard for people who've been there to explain in words what's fascinating about it, but they all agree with it: Compared to other places, the glaciers are bluer, the air is colder, the mountains are more frightening, and the scenery is more haunting," said Seth Sykora-Bodie, a marine scientist and National Geographic explorer at the National Oceanic and Atmospheric Administration (NOAA).
In 1915, National Geographic began mapping, and since then four oceans have been identified: the Atlantic, Pacific, Indian, and Arctic Oceans. On this year's World Oceans Day, National Geographic declared recognition of the world's fifth largest ocean, the Southern Ocean.
"Scientists have long announced the existence of the Southern Ocean, but since there has never been an international agreement, we have never officially recognized it," said Alex Tait, a geographer at the National Geographic Society.
Geographers argue about whether the waters around Antarctica are of enough character to deserve a separate name, or whether the cold waters are merely the southern extension of the Pacific, Atlantic and Indian Oceans.
"In a sense, we're like geography nerds," Tait said. Scientists and the media have increasingly used the term "Southern Ocean" over the years, and he and the National Geographic Society's Map Policy Committee have been pondering the change.
He added that this trend of change is consistent with national geographic societies advocating for the protection of the world's oceans and drawing public attention to areas in urgent need of protection.
"We've been labeling it, but it's a little bit different [than it's been to other oceans]," Tait said, "and this time we took the final step to show that we want to acknowledge it because there's ecological isolation here." ”
Marine biologist and National Geographic explorer Sylvia Earle praised the map update.
"Although we only have one interconnected ocean, it is all too good that National Geographic formally recognizes the water body around Antarctica as the Southern Ocean," Earle wrote in an emailed statement: "Surrounded by the extremely fast-flowing Antarctic Circumpolar Current, the Southern Ocean is the only ocean that is in contact with the other three oceans and completely surrounds the Antarctic continent, rather than surrounded by them." ”
Ocean currents define the ocean
Other oceans are defined by the continents that surround them, while the Southern Ocean is defined by ocean currents.
Scientists estimate that the Antarctic Circumpolar Current formed about 34 million years ago, when Antarctica separated from South America. As a result, seawater can flow unimpeded in Antarctica.
The Antarctic Circumpolar Current flows from west to east around Antarctica, forming a wave zone centered roughly at 60 degrees south latitude, which is now the northern boundary of the Southern Ocean. Compared to the northern seawater, the sea water within the Polar Current in the Antarctic is colder and slightly less salinity.
The Antarctic Circumpolar Current stretches from the surface to the seabed, transporting more seawater than any other current. It absorbs the waters of the Atlantic, Pacific and Indian Oceans, helping to drive a global circulatory system known as a "conveyor belt" that transfers heat around the planet. Cold, dense water sinks into the ocean floor of Antarctica, helping to sequester carbon into the deep ocean. In both respects, the Southern Ocean is of vital importance to the Earth's climate.
Currently, scientists are studying how human-induced climate change is changing the Southern Ocean. Scientists have found that the seawater flowing around the poles across Antarctica is warming, but aren't sure how much of an impact this will have on Antarctica. At the place closest to land in the Antarctic around the polar current, the rapid melting of continental ice sheets and ice shelves has occurred.
A different environment
At present, the Antarctic Current encloses the cold southern waters, helping to maintain the low temperature of Antarctica and maintain the ecological uniqueness of the Southern Ocean. There are thousands of species living here, and there is no way back.
The Southern Ocean "has a unique and fragile marine ecosystem inhabited by wonderful marine life such as whales, penguins and seals," said National Geographic resident explorer Enric Sala.
What's more, the Southern Ocean also has ecological impacts elsewhere. For example, humpback whales feed on krill near the South Pole and migrate north in the winter, spending their time in different ecosystems in South and Central America. Some seabirds also pass through here when they migrate.
By drawing attention to the Southern Ocean, the National Geographic Society hopes to promote its conservation.
In the Southern Ocean, for decades, there have been concerns about the impact of industrial fishing on species such as krill and small-scaled canine tooth Antarctica, aka Chilean sea bass. In 1982, fishing restrictions were imposed. In 2016, the world's largest marine protected area was established in the Ross Sea in west Antarctica. Some organizations are working to set aside more MPAs to protect the most important foraging areas in the Southern Ocean, such as the waters off the Antarctic Peninsula.
"There are a lot of countries around the world that support protecting these areas and banning industrial fishing," Sala said.
Depict the real world
In the late 1970s, the National Geographic Society hired a geographer to review changes and adjustments on all published maps. In 2016, the heavy lifting fell into Tait's hands.
He claimed to have approached the matter in a journalistic way, including paying attention to current affairs and knowing who controlled which areas at the first time.
"It's important that this is a map policy, not a policy of National Geographic's position on (geopolitical) disputes," he said. For example, national geographic maps show that Britain controls the Falkland Islands, although Argentina also claims sovereignty. In disputed areas, Tait works with geographers and editors to determine the most accurate description of a region.
Every week or every two weeks, there are some minor changes, while major changes like determining the Southern Ocean are rarer.
Typically, when it comes to naming oceans, National Geographic follows the rules of the International Hydrographic Organization (IHO). While not directly responsible for the identification of geographical names, IHO, in cooperation with the United Nations Group of Experts on Geographical Names, regulates geographical names at an international level. In 1937, the IHO recognized the Southern Ocean in its guidelines, but in 1953 it was cancelled due to controversy. Since then, the issue has been under consideration, but it has not been agreed upon by the members of the organization and has therefore not been able to restore the name Of the Southern Ocean.
However, the United States Geographical Names Commission has been using this geographical name since 1999. In February, NOAA officially recognized the Southern Ocean as unique.
Tait said National Geographic's new policy will affect children in schools to see the world on a map.
"I think one of the biggest impacts is education," he said, "and we're looking at the oceans, opening the door for students to understand the ocean world." If the Southern Ocean is not included, students will not be able to understand its uniqueness and importance. ”
(Translator: Sky4)