Antarctic circumpolar current evolution and its relation to southern hemisphere westerly winds during the holocene

The Antarctic Circumpolar Current (ACC), Earth’s largest ocean current system, significantly influences global ocean circulation and climate. Despite its importance, the driving forces behind the ACC remain largely elusive. This study, utilizing simulation data combined with reconstructed data, explores the ACC’s evolution and its relationship with the Southern Hemisphere Westerly Winds (SWW) during the Holocene. Both simulation and reconstruction results indicate that the ACC strengthened and shifted poleward during the Holocene. Concurrently, the SWW also intensified and migrated poleward. The ACC’s increasing trend is driven by two ways related to the increase in Southern Hemisphere (SH) temperature. One way operates in the ocean, where rising SH mid-latitude seawater temperature lead to sea ice melt. Consequently, seawater salinity and density decrease. Simultaneously, the south-to-north gradient of salinity and density increases, thereby strengthening the ACC during the Holocene. The other way operates in the atmosphere, where raises SH mid-latitude surface temperature. Simultaneously, sea level pressure decreases. However, the south-to-north gradient of both surface temperature and sea level pressure intensify. These enhanced gradients lead to increased wind stress, which intensifies the SWW and induces a poleward shift. The intensified SWW further amplify the ACC and drive its poleward migration during the Holocene. In summary, the ACC’s strengthening during the Holocene resulted from rising SH temperatures, which altered the meridional gradients of seawater temperature, salinity, and density in the ocean. Concurrently, intensified atmospheric temperature and pressure gradients amplified wind stress and the SWW, further reinforcing the ACC.