The Antarctic Circumpolar Current (ACC), the world’s strongest ocean current, is on track to slow down by 20% by 2050 due to climate change, according to new research. Flowing clockwise around Antarctica, the ACC is a key driver of the global ocean “conveyor belt,” which helps regulate Earth’s climate by distributing heat, nutrients, and carbon across the planet. However, fresh water from melting Antarctic ice is disrupting this vital system, with potentially catastrophic consequences for global ecosystems, weather patterns, and sea levels.
How the Antarctic Circumpolar Current Works
The ACC is unlike any other ocean current—it is the only one that flows unimpeded around the planet, linking the Pacific, Atlantic, and Indian Oceans. It is five times stronger than the Gulf Stream and carries more than 100 times the water volume of the Amazon River. Acting as a protective barrier, it helps shield Antarctic ice sheets from warm waters and prevents invasive species from reaching the continent.
Read More: Ancient tomb of King Thutmose II unearthed near Luxor
Unlike better-studied currents like the Gulf Stream or the Kuroshio Current near Japan, the ACC remains less understood due to its remote location. This knowledge gap has made it difficult to predict how climate change will impact the current’s strength and stability.
The Role of Climate Change
Ocean currents are influenced by temperature, salinity, wind patterns, and sea ice extent. Warming oceans should, in theory, speed up the ACC, as warm water is less dense and shifts ocean dynamics. However, researchers have found that massive volumes of fresh meltwater from Antarctica are counteracting this effect.
Using Australia’s fastest supercomputer, scientists developed a high-resolution ocean model that captures details such as eddies—key features in ocean circulation often missed by traditional models. Their findings reveal that as cold, fresh meltwater moves north, it alters the ocean’s density structure, ultimately slowing the ACC. This phenomenon mirrors changes seen in the Arctic, where disruptions to ocean currents have contributed to more extreme weather and faster sea-level rise.
Far-Reaching Consequences
A weaker ACC could have devastating global effects. As the primary force that distributes nutrient-rich waters around Antarctica, it plays a crucial role in maintaining marine biodiversity. A slowdown could decrease the productivity of fisheries, harming coastal communities reliant on them. It may also allow invasive species, such as southern bull kelp, to reach Antarctica, disrupting fragile ecosystems.
More alarmingly, a weaker ACC would allow warm ocean waters to creep southward, accelerating Antarctic ice melt. This could set off a vicious cycle—more melting would lead to more fresh water in the ocean, further weakening the current and intensifying sea-level rise.
Additionally, the slowdown of the ACC could reduce the ocean’s ability to absorb carbon dioxide and heat, weakening one of Earth’s natural defenses against climate change. This could lead to more climate variability, including extreme weather events and prolonged marine heatwaves, such as those that have already damaged coral reefs in Australia and New Zealand.
Read More: Oldest modern bird fossil found in Antarctica sheds light on avian …
Despite the alarming projections, scientists emphasize that the future is not set in stone. Reducing greenhouse gas emissions could help limit Antarctic ice melt, slowing the weakening of the ACC. Long-term monitoring in the Southern Ocean will be crucial to understanding how the current evolves and how mitigation strategies can be developed.