Strongest ocean current will slow with melting Antartic ice sheets

The Antarctic Circumpolar Current (ACC) could slow by around 20 per cent by 2050 in a high carbon emissions scenario, researchers from the University of Melbourne and NORCE Norway Research Centre have found.

More than four times stronger than the gulf stream, the ACC is a crucial part of the world's "ocean conveyor belt", which moves water around the globe - linking the Atlantic, Pacific and Indian oceans.

The melting of the ice sheets would see an influx of fresh water into the Southern Ocean, changing its salinity and circulation.

Fluid mechanist Bishakhdatta Gayen, climate scientist Taimoor Sohail, and oceanographer Andreas Klocker, analysed a high-resolution ocean and sea ice simulation to diagnose the impact of changing temperature, saltiness and wind conditions.

Gayen said the ocean was 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."

The ACC works as a barrier to invasive species from other continents reaching Antarctica. As the ACC slows and weakens, there is a higher likelihood such species will make their way into the fragile Antarctic continent.

Sohail said it is predicted that the slow-down would be similar under a lower emissions scenario, provided ice melting accelerates as predicted in other studies.

"The 2015 Paris Agreement aimed to limit global warming to 1.5 degrees Celsius above pre-industrial levels. Many scientists agree that we have already reached this 1.5 degree target, and it is likely to get hotter, with flow-on impacts on Antarctic ice melting," Sohail said.

"Concerted efforts to limit global warming (by reducing carbon emissions) will limit Antarctic ice melting, averting the projected ACC slowdown."

-- BERNAMA