Antarctic Circumpolar Current

The Antarctic Circumpolar Current (ACC) is a strong ocean current that flows clockwise around Antarctica. It is also called the West Wind Drift. It is the largest ocean current in the world, moving a huge amount of water. Because there are no landmasses to block it, the ACC circles the whole continent. This helps keep warm waters away from Antarctica, allowing the continent to keep its massive ice sheet.

This current is very important for marine life. Where the cold Antarctic waters meet warmer subantarctic waters, a zone called the Antarctic Convergence forms. This area brings up nutrients from deep water, feeding tiny plants called phytoplankton. These support small animals like copepods and krill. Krill, in turn, feed fish, whales, seals, penguins, albatrosses, and many other species.

Sailors have known about the ACC for centuries. It speeds up travel from west to east but makes it very hard to sail from east to west. Famous stories like Jack London’s "Make Westing" and events around the mutiny on the Bounty show how difficult it was for ships trying to go west around Cape Horn. The fastest sailing route in the world, the eastbound clipper route, follows the ACC around three major capes: Cape Agulhas in Africa, South East Cape in Australia, and Cape Horn in South America. The ACC also helps create large circular patterns of water called the Ross and Weddell Gyres.

Structure

The Antarctic Circumpolar Current connects the Atlantic, Pacific, and Indian Oceans. It lets water move between them. The current flows around Antarctica, passing through places like the Drake Passage between South America and the Antarctic Peninsula.

As it moves, the current splits and changes direction because of underwater mountains and islands.

The current has three main parts, called fronts. These are the Subantarctic front, the Polar front, and the Southern ACC front. These fronts help separate different kinds of water. The ACC is the strongest ocean current, moving a lot of water around the world.

Dynamics

The Antarctic Circumpolar Current is pushed by strong westerly winds in the Southern Ocean. Because no land blocks it, the current flows all the way around Antarctica. The winds push the water, and Earth’s rotation helps guide its path.

The current moves at a speed of about 4 kilometers per hour. It also changes over time, affected by patterns like the Antarctic Circumpolar Wave and the Antarctic oscillation. These patterns influence the winds and climate in the southern hemisphere.

Formation

The Antarctic Circumpolar Current started when Antarctica was separated from other lands. This happened when water paths, like the Tasmanian Passage and the Drake Passage, opened up. These changes helped cool the Earth and made Antarctica cold and icy. Scientists believe these passages opened millions of years ago, and they helped shape Earth's climate.

Phytoplankton

Antarctic sea ice changes with the seasons. It shrinks in February and March and grows in August and September. When the ice melts, it brings nutrients from deep water to the surface. This helps tiny plants called phytoplankton grow. These phytoplankton feed many sea animals, including whales, seals, and birds.

Phytoplankton growth needs sunlight and nutrients like iron. The Antarctic Circumpolar Current helps these tiny plants grow, especially a type called diatoms. Phytoplankton play an important role in taking carbon from the air, which helps keep our planet healthy.

Studies

In May 2008, 19 scientists studied the Antarctic Circumpolar Current. They wanted to learn how it changes the Southern Ocean’s effects of climate change. This current links the Atlantic, Indian, and Pacific Oceans. It moves a lot of water—more than all the world’s rivers put together. It helps shape the climate and marine life.

The current also protects old wooden ships, like Ernest Shackleton’s Endurance, by stopping creatures called “ship worms” from harming them. Some recent reports say the current might be getting weaker. This could change ocean patterns and affect the climate in many places.