Antarctic Circumpolar Current Poised for Major Shift, Threatening Ecosystems and Sea Levels
A dramatic shift in the Antarctic Circumpolar Current (ACC), the largest ocean current on Earth, is predicted to occur, potentially triggering widespread consequences for global climate and ecosystems. New research published in Nature Communications reveals the ACC has undergone meaningful changes in velocity and location during past warm periods, and a similar response could be unfolding now.
The ACC, a critical component of Earth’s climate system, encircles Antarctica and plays a vital role in regulating global temperatures and distributing heat. researchers from the University of Bonn Institute of Geosciences have discovered that during a warm period approximately 130,000 years ago, the ACC’s velocity was more than three times greater than in recent millennia. This acceleration was linked to changes in Earth’s orbit and the amount of solar radiation reaching the planet, a cycle that repeats roughly every 100,000 years, alongside variations in earth’s axial tilt and rotation every 21,000 years.
During that same period, the ACC also shifted southward towards Antarctica by approximately 600 kilometers (372 miles), bringing warmer waters closer to the Antarctic ice sheets. This warming contributed to sea levels 6 to 9 meters (19 to 30 feet) higher during the last interglacial period, according to the study.
“The velocity in the second-to-last warm period, roughly 130,000 years ago was more than three times greater than in the last millennia comprising the current warm period,” explained Dr. Michael Weber, study author.
While current observations indicate the ACC is speeding up – a phenomenon previously reported by iflscience – the new modeling suggests a potential northward drift, which would counteract the southward shift predicted by warming temperatures. This complex dynamic underscores the sensitivity of the ACC to climate fluctuations.
Any considerable change to the ACC could have cascading effects on marine ecosystems, coastal regions, and global climate patterns. Researchers warn that understanding these potential shifts is crucial for predicting future sea level rise and mitigating the impacts of climate change.
