The ocean is filled with different currents, which keep the water cycling around the world. These currents don’t just move the water, however.

They are also responsible for moving heat around the planet, locking carbon into the oceans, moving nutrients around, and, of course, helping animals in their travels.

The largest current in the world is known as the Antarctic Circumpolar Current (ACC). It flows clockwise around Antarctica from west to east, and is responsible for moving about 182 million cubic meters of water every second.

While this current has been stable for a long time, that has not always been the case, and researchers believe that it is starting to change.

The international team of scientists has taken core samples from 3000-4000 meters (9800-13,100 feet) below the surface of the Scotia Sea. These core samples can provide significant information about what the water was like in years past.

One key thing that they can look at is the tiny grains of particles in the water. The size of the grains helps show researchers how fast the currents were moving. The faster it moves, the longer it would take for grains to settle onto the ocean floor.

Using this method, researchers determined that the ACC was once a lot stronger during previous warm periods. They published their findings in a study in the journal Nature Communications.

In a statement about the study, Dr. Michael Weber from the University of Bonn Institute of Geosciences, who is an author of the study, said:

“The velocity in the second-to-last warm period, roughly 130,000 years ago was more than three times greater than in the last millennia comprising the current warm period.”

They believe that the change in speed of the current was due to the increased speed in the Earth’s orbit around the sun, which changed how much solar radiation reached teh planet.

This cycle shifts every 100,000 or so years. In addition, every 21,000 years, the Earth’s axis changes.

During that time, the ACC shifted south toward Antarctica by about 600 kilometers (372 miles). Weber explains:

“This brought warmer waters closer to the Antarctic ice sheets, which may have contributed to sea level being 6 to 9 meters higher [19 to 30 feet] in the last interglacial.”

While a shift in this current can, and will, have a dramatic impact on the climate, it is not going to happen overnight. This type of shift takes hundreds, or even thousands, of years to complete.

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