Ammon News - Melting ice sheets are slowing the Antarctic Circumpolar Current (ACC), the world's strongest ocean current, researchers have found.

This melting has implications for global climate indicators, including sea level rise, ocean warming and viability of marine ecosystems.

The researchers, from the University of Melbourne and NORCE Norway Research Centre, have shown the current slowing by around 20 per cent by 2050 in a high carbon emissions scenario.

This influx of fresh water into the Southern Ocean is expected to change the properties, such as density (salinity), of the ocean and its circulation patterns.

University of Melbourne researchers, fluid mechanist Associate Professor Bishakhdatta Gayen and climate scientist Dr Taimoor Sohail, and oceanographer Dr Andreas Klocker from the NORCE Norwegian Research Centre, analysed a high-resolution ocean and sea ice simulation of ocean currents, heat transport and other factors to diagnose the impact of changing temperature, saltiness and wind conditions.

Associate Professor 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."

The ACC works as a barrier to invasive species, like rafts of southern bull kelp that ride the currents, or marine-borne animals like shrimp or molluscs, from other continents reaching Antarctica.

As the ACC slows and weakens, there is a higher likelihood such species will make their way onto the fragile Antarctic continent, with a potentially severe impact on the food web, which may, for example, change the available diet of Antarctic penguins.

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 and is the main mechanism for the exchange of heat, carbon dioxide, chemicals and biology across these ocean basins. Science Daily