Antarctic

Lore & Background

The Antarctic is the polar region surrounding the South Pole, situated opposite the Arctic. It is defined by the Antarctic Circle and encompasses the continent of Antarctica, the Kerguelen Plateau, and various island territories. The region is bounded by the Antarctic Convergence, a shifting zone where cold Southern Ocean waters meet warmer northern waters, and covers roughly one-fifth of the Southern Hemisphere. The continent itself accounts for about 5.5 percent of this area, with a surface of 14 million square kilometers. All land and ice shelves south of the 60th parallel south fall under the Antarctic Treaty System. The Antarctic realm is one of eight major biogeographic realms on Earth. The region lacks any permanent human population or country. Its appearance is dominated by vast ice shelves, waters, and the Antarctic ice sheet, whose melting poses a significant risk to global sea levels and disrupts Southern Ocean circulation, impacting local climate and marine ecosystems. The continent is almost entirely covered in ice and snow, with less than one percent of land exposed. Only two species of flowering plants grow there, alongside mosses, liverworts, lichens, and macrofungi. Wildlife includes seals, penguins, albatrosses, petrels, whales, various fish like Antarctic icefish and toothfish, squid such as the colossal squid, and Antarctic krill. The region contains the world’s largest protected area, the South Georgia and the South Sandwich Islands Marine Protection Area. All ships over 500 tonnes in Antarctic waters must follow the Polar Code regulations adopted by the International Maritime Organization.

Reader's Guide

The Antarctic region is significant for its unique governance under the Antarctic Treaty System, which administers all land and ice shelves south of 60°S latitude. The region covers about 20 percent of the Southern Hemisphere and includes the continent of Antarctica, the Kerguelen Plateau, and various island territories. Climate change in Antarctica is particularly important because melting of the Antarctic ice sheet has a high potential to add to global sea level rise and disrupts the Southern Ocean overturning circulation, affecting local climate and marine ecosystem functioning. The present inhabitants comprise a few thousand transient scientific and other personnel working at research stations maintained by various countries.

Did You Know?

• The Antarctic region south of 60°S covers only about 4-5% of Earth's surface, roughly 8-10% of the Southern Hemisphere.
• The Antarctic hosts the world's largest protected area, the Ross Sea Region Marine Protected Area, covering over 2 million km².

Physical Extent and the Race to the Bottom

The Southern Ocean spans roughly 21.96 million square kilometres, making it the second-smallest of the five principal oceanic divisions — larger than the Arctic but dwarfed by the Pacific, Atlantic, and Indian. It encircles Antarctica and is generally defined as the waters south of 60° S latitude. In early February 2019, the Five Deeps Expedition pushed multibeam sonar into the ocean's deepest reaches, pinpointing a maximum depth of 7,434 metres at coordinates 60° 28' 46"S, 025° 32' 32"W. Expedition leader and chief submersible pilot Victor Vescovo descended to the seafloor aboard the crewed submersible DSV Limiting Factor on February 3, 2019, becoming the first person to visit that point. In honour of the vessel, Vescovo proposed naming the abyssal trench the "Factorian Deep," a designation that ties the discovery directly to the machine that made it possible. The survey confirmed that even this relatively compact ocean conceals depths comparable to the world's great trenches.

A Century of Cartographic Dispute

For well over a hundred years, geographers could not agree whether the waters ringing Antarctica constituted a distinct ocean or merely the southern fringes of the Pacific, Atlantic, and Indian. James Cook's voyages in the 1770s demonstrated that open seas enclosed the southern latitudes, yet no single boundary was ever settled. The International Hydrographic Bureau, predecessor to today's IHO, first convened in 1919 and published its Limits of Oceans and Seas in 1928, drawing the Southern Ocean's northern edge along Cape Horn, Cape Agulhas, the Australian coast, and Broughton Island. By 1937 the limits had shifted southward, detaching much of the boundary from land. After 1953 the ocean was dropped from the official publication entirely, leaving individual hydrographic offices to draw their own lines. The 2000 IHO revision finally reinstated the Southern Ocean as the waters south of the northern limit of its overturning circulation, yet the definition remains unformally adopted because of unrelated naming disputes, such as the Sea of Japan controversy.

The Circulation Engine and Climate Risk

The Southern Ocean's overturning circulation forms the second half of the planet's thermohaline conveyor, complementing the better-known Atlantic meridional overturning circulation. Together these two loops redistribute heat and salt across the globe, and the Southern Ocean's role was a key factor in the IHO's 2000 decision to recognise it as a separate body of water. However, ongoing climate change is already altering the system. Warming has increased ocean stratification, and researchers warn the circulation could slow dramatically or even pass a tipping point and collapse outright. Such a collapse would ripple outward, disrupting global weather patterns and undermining the marine ecosystems that depend on the ocean's nutrient transport, with effects unfolding over centuries. Even before any tipping point is reached, the ongoing warming is measurably reshaping the Southern Ocean's marine communities, making the region both a barometer and a casualty of the broader climate crisis.

From Balboa's 'Southern Ocean' to National Geographic

The phrase "Southern Ocean" carries a confusing lineage. The Spanish explorer Vasco Núñez de Balboa, the first European to sight the Pacific from Panama, originally applied the name to that vast body of water, and the term lingered in British legislative language as late as 1745, when an Act of Parliament offered a prize for finding a Northwest Passage to "the Western and Southern Ocean of America." Throughout the eighteenth and nineteenth centuries, writers used the label for the unknown polar waters with wildly different northern boundaries — 40 degrees, 50 degrees, the Antarctic Circle, or lines connecting Cape Horn, the Cape of Good Hope, and New Zealand. The Australian Government still treats the Southern Ocean as lying immediately south of its own coastline. It was not until June 2021 that the National Geographic Society formally recognised the ocean on its maps, having previously rendered it in a distinct typeface and extending the Pacific, Atlantic, and Indian Oceans all the way to Antarctica.