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Why does the Southern Ocean have a powerful circumpolar current?

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World map showing major ocean current systems, with arrows indicating the direction and speed of warm and cold currents in the Atlantic, Pacific, Indian, Southern, and Arctic Oceans. Warm currents are marked in red and cold currents in blue, with currents labeled by name and symbols denoting those that reverse direction seasonally. A legend explains current speed categories and color codes. — ocean current Major ocean current systems of the world.

The Southern Ocean features a powerful, wind-driven circumpolar current known as the Antarctic Circumpolar Current (ACC) primarily because it is the only region on Earth where a continuous, deep-ocean belt encircles the globe without being interrupted by continental landmasses.123

This unique geographic configuration allows the current to flow unimpeded from west to east around Antarctica. The ACC is driven by prevailing winds and is further influenced by submarine topography and the exchange of water masses at various depths. Because there is no continuous open water bordering the Arctic in the Northern Hemisphere, it lacks a corresponding powerful circumpolar current.12

The ACC plays a critical role in global oceanography by isolating Antarctica from warmer subtropical waters and facilitating the thermohaline circulation through the upwelling of deep water, which is then converted into Antarctic Bottom Water and Antarctic Intermediate Water.4