The Antarctic Circumpolar Current is the planet's most powerful and arguably most important. It is the only one to flow clear around the globe without getting diverted by any landmass, sending up to 150 times the flow of all the world's rivers clockwise around the frozen continent. It connects all the other oceans, and is thought to play a key role in regulating natural climate swings that have repeatedly swept the earth for millions of years. But much is still not known about how it works, including how it might now respond to human-induced climate change.
* This article was originally published here