Southern Ocean

Southern ocean is the newest named ocean, officially recognized as the waters surrounding Antarctica and connecting the Atlantic, Indian, and Pacific basins. It circles the continent in a cold ring, with boundaries usually drawn near 60 degrees south latitude where sharp temperature fronts separate polar water from warmer subantarctic water.

The Antarctic Circumpolar Current (ACC) races eastward around the continent, driven by persistent westerly winds. As the only current to flow completely around the globe, it transfers heat, salt, and nutrients between oceans. Upwelling south of the Polar Front brings deep, carbon-rich water to the surface, while sinking near the Antarctic Divergence helps lock carbon in the deep sea.

Seasonal sea ice doubles the ocean's surface area each winter, then melts back during summer's 24-hour daylight. Pieces of glacial ice calve into tabular icebergs that drift with currents. Katabatic winds spilling off the Antarctic Ice Sheet push newly formed ice away from the coast, creating coastal polynyas that act as sea-ice factories.

Life here relies on Antarctic krill, a shrimp-like crustacean that feeds on phytoplankton blooming under the ice edge. Penguins, whales, seals, and seabirds depend on krill, while benthic communities cling to the continental shelf. The Southern Ocean also hosts long-lived toothfish, glass sponges, and microbes adapted to near-freezing water.

Research stations from many countries dot the coastline and islands, collecting data on weather, ozone, and ocean chemistry. Fisheries for krill and Patagonian toothfish are managed under the Convention on the Conservation of Antarctic Marine Living Resources (CCAMLR). Scientists watch for warning signs such as melting ice shelves, ocean acidification, and shifting storm belts that could alter this important climate regulator.