The Antarctic Circumpolar Current (ACC) world’s strongest ocean current now slowing down due to unchecked melting of the Antarctic ice sheet. This powerful current flows from west to east around Antarctica plays a crucial role in regulating global climate and ocean circulation.
A team of researchers from the University of Melbourne analyzed high resolution ocean and sea ice simulations to assess how changing temperature, salinity and wind conditions are affecting ocean currents. Their findings published in Environmental Research Letters suggest that the influx of freshwater from melting ice is significantly weakening the ACC.
Associate Professor Bishakhdatta Gayen said “The ocean is extremely complex and finely balanced, If this current ‘engine’ breaks down there could be severe consequences including more climate variability with greater extremes in certain regions and accelerated global warming due to a reduction in the ocean’s capacity to act as a carbon sink.”
As Antarctic ice melts, vast amounts of freshwater pour into the Southern Ocean reducing salinity and disrupting ocean circulation. This affects the ACC’s ability to drive the global ocean conveyor belt, which distributes heat, nutrients, and carbon dioxide across the Atlantic, Pacific, and Indian Oceans.
Disruptions Beyond Climate
Beyond its role in climate regulation, the ACC acts as a natural barrier that prevents invasive species from reaching Antarctica. A slowing current could allow non-native marine life, such as bull kelp or mollusks, to invade and disrupt the delicate Antarctic ecosystem, affecting food sources for native species like penguins.
Supercomputer Simulations Challenge Previous Studies
Using Australia’s fastest supercomputer, GADI the high-resolution climate model ACCESS-OM2-01, researchers found that ice melt plays a dominant role in slowing the ACC. These results challenge earlier studies suggesting that the ACC might accelerate due to increasing temperature disparities across latitudes.
Instead the study underscores that the primary driver of the slowdown is the massive influx of freshwater from Antarctic ice melt, a direct consequence of human-induced climate change.
With the ACC playing such a pivotal role in Earth’s climate system, its weakening could have far-reaching implications reinforcing the urgency for stronger climate action to curb global warming and protect polar ice sheets from further deterioration