The Antarctic Circumpolar Current (ACC), the most powerful ocean current in the world, is slowing down due to ice melt. This alarming discovery could disrupt global climate and marine ecosystems.
Researchers from the University of Melbourne and the NORCE Norway Research Centre predict a 20% weakening of the ACC by 2050. This slowdown is attributed to the influx of freshwater from melting ice, altering the salinity and density of the ocean.
Snapshot of the surface speed of the Antarctic Circumpolar Current.
The ACC plays a crucial role in global ocean circulation, acting as a conveyor of water, heat, and carbon between the Atlantic, Pacific, and Indian Oceans. Its weakening could lead to an increase in climate extremes and reduce the ocean's ability to absorb CO2.
Scientists used high-resolution simulations to study the impacts of temperature, salinity, and wind condition changes on ocean currents. These models reveal increased complexity in the ocean's responses to global warming.
The weakening of the ACC could also allow invasive species to reach Antarctica, threatening its fragile ecosystem. This situation could alter the food chain, affecting penguins in particular. Projections show that even in low-emission scenarios, the slowdown of ocean circulation could persist.
Published in
Environmental Research Letters, this study contrasts with previous ones that suggested an acceleration of the ACC. It highlights the need for further research to fully understand the impacts of climate change on ocean currents.
What is the Antarctic Circumpolar Current (ACC)?
The Antarctic Circumpolar Current (ACC) is a major ocean current that surrounds Antarctica. It is considered the most powerful ocean current in the world, playing a key role in the thermohaline circulation, also known as the 'ocean conveyor belt'.
The ACC connects the three main ocean basins: the Atlantic, Pacific, and Indian. It facilitates the exchange of heat, carbon, and nutrients between these oceans, thus influencing global climate and marine ecosystems.
This current is driven by the westerly winds that blow around Antarctica. Its strength and direction are also influenced by underwater topography and differences in water density, due to temperature and salinity.
The ACC acts as a natural barrier, preventing warm waters from lower latitudes from penetrating the cold waters of Antarctica. This helps maintain the region's climate balance and protect its unique ecosystems.
How does ice melt affect ocean currents?
The melting of polar ice, particularly in Antarctica, releases large amounts of freshwater into the ocean. This freshwater is less dense than saltwater, which alters the stratification of ocean layers and affects marine currents.
The influx of freshwater reduces the salinity of surface water, which can weaken deep ocean currents, such as the Antarctic Bottom Water. These currents are essential for thermohaline circulation, which redistributes heat and nutrients across the oceans.
The slowing of ocean currents can lead to an accumulation of heat in certain regions, exacerbating the effects of global warming. This can also disrupt marine ecosystems by altering habitats and food sources for many species.
Finally, ice melt and the slowing of ocean currents can impact sea levels. Slower ocean circulation can lead to a rise in sea levels in some regions, while others might experience a relative decrease.