Researchers from the University of Melbourne and NORCE Norway Research Center, have shown the Antarctic Circumpolar Current (ACC) slowing by around 20% by 2050 in a high carbon emissions scenario. The work is published in the journal Environmental Research Letters.
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.
“The melting ice sheets dump vast quantities of fresh water into the salty ocean. This sudden change in ocean ‘salinity’ has a series of consequences—including the weakening of the sinking of surface ocean water to the deep (called the Antarctic Bottom Water), and, based on this study, a weakening of the strong ocean jet that surrounds Antarctica,” 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 mollusks, 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.