Antarctic Circumpolar Current Formation Study

New research published in the Proceedings of the National Academy of Sciences of the United States of America, led by Hanna Knahl of the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, reveals how the Antarctic Circumpolar Current (ACC) first developed. The study challenges previous theories, showing that the opening of ocean gateways between Antarctica, South America, and Australia was not sufficient for the ACC's full formation. Instead, strong westerly winds blowing through the Tasman Gateway, after Australia had moved further from Antarctica, were crucial. The research used advanced climate and ice sheet models to simulate Earth's geography 33.5 million years ago, demonstrating how the ACC's early stages influenced global ocean circulation and carbon uptake, contributing to the shift from a warm greenhouse climate to the cooler Cenozoic Ice Age. Co-authors Gerrit Lohmann and Johann Klages also contributed to the study, which highlights the complex interactions between ice, atmosphere, land surface, and ocean.