Earth's most powerful ocean current is slowing and the impact could be huge – here’s why

Antarctic Meltwater Slows Earth's Strongest Ocean Current

The world’s oceans are changing in ways we can't ignore. New research suggests that Antarctic ice melt is slowing the planet’s most powerful ocean current. This shift could affect sea levels, ocean temperatures, and Antarctica’s delicate ecosystem.

The Antarctic Circumpolar Current moves clockwise around Antarctica. It transports nearly a billion litres of water per second. This current keeps warm waters away from the Antarctic Ice Sheet. It also links the Atlantic, Pacific, Indian, and Southern Oceans, helping regulate global temperatures.

Climate change has caused Antarctic ice to melt at an alarming rate. This releases fresh, cold water into the Southern Ocean. Scientists used Australia’s fastest supercomputer to study its effects. Their findings show that the meltwater weakens the current by changing water density. It also slows convection, which moves cold water from the surface to the deep ocean. Over time, this could lead to further warming of the Southern Ocean.

The Global Impact of a Slower Current
A weaker current means more warm water could reach Antarctica. This would cause even more ice to melt, worsening sea level rise. The cycle of melting and slowing could continue for decades. Scientists predict the current may weaken by 20% by 2050.

The Antarctic Circumpolar Current also acts as a barrier. It stops invasive species from reaching Antarctica’s shores. A slowdown could make this defence less effective. More non-native species could reach the continent, disrupting its ecosystem.

Experts warn that the effects of this slowdown will be global. Changes in Antarctic waters could alter ocean circulation worldwide. However, long-term monitoring is needed to understand the full impact.