New research has found that melting Antarctic ice sheets are slowing down the Antarctic Circumpolar Current (ACC)—the world’s strongest ocean current.

This slowdown could have serious effects on global climate, including rising sea levels, ocean warming, and disruptions to marine ecosystems.

Why Is this happening?

Scientists from the University of Melbourne and NORCE Norway Research Center discovered that by 2050, the ACC could slow down by 20% if carbon emissions remain high.

Their study, published in Environmental Research Letters, shows that melting ice sheets are releasing massive amounts of freshwater into the Southern Ocean.

This is changing the ocean’s salinity (salt levels) and density, which directly affects how ocean currents flow.

Using a high-resolution climate model, researchers analyzed how changes in temperature, saltiness, and wind patterns influence ocean circulation.

Their findings suggest that if the ACC weakens, it could lead to more extreme climate events in different parts of the world and reduce the ocean’s ability to absorb carbon dioxide. This could accelerate global warming.

The ACC is over four times stronger than the Gulf Stream and plays a key role in circulating ocean water around the world.

It connects the Atlantic, Pacific, and Indian Oceans, transporting heat, carbon dioxide, and nutrients across the globe.

One of its important functions is acting as a barrier that prevents invasive species—such as certain types of kelp, shrimp, and mollusks—from reaching Antarctica.

If the ACC weakens, these species may invade the fragile Antarctic ecosystem, affecting the food supply for animals like penguins and other marine life.

Scientists used Australia’s fastest supercomputer, GADI, to run their climate models. The results suggest that if ice melting continues to increase, the ACC will keep slowing down, even under lower carbon emission scenarios.

Dr. Taimoor Sohail, a climate scientist involved in the study, pointed out that the Paris Agreement in 2015 aimed to limit global warming to 1.5°C above pre-industrial levels.

However, many scientists believe that we have already reached this limit, and temperatures may continue to rise.

“The more global warming we allow, the more Antarctic ice will melt, which will further slow down the ACC,” Dr. Sohail said. “Reducing carbon emissions is crucial to preventing this slowdown.”

A surprising discovery

Earlier studies suggested that the ACC was getting faster due to increasing temperature differences between ocean latitudes. However, this new research challenges that idea, showing that freshwater from melting ice sheets is actually slowing the current down.

Associate Professor Bishakhdatta Gayen, one of the lead researchers, emphasized that more observational studies are needed to fully understand how the ACC will respond to climate change. “The ocean is a complex system, and this new study highlights a previously unknown process that could have major climate impacts.”

The study reinforces the urgent need to reduce carbon emissions to slow down global warming. If left unchecked, the weakening of the ACC could lead to more climate instability, rising sea levels, and disruptions to the marine ecosystems that millions of people and animals depend on.

By taking action to protect our planet, we may still be able to preserve the balance of our oceans and prevent further damage to Antarctica’s fragile environment.