Increasing Decline in Antarctic Bottom Water Volume Since 2000s

Geophysical Research Letters, 9 July 2026

Antarctic Bottom Water (AABW) is the cold, dense water formed around Antarctica that sinks to the deepest parts of the ocean. It helps drive global ocean circulation and stores large amounts of heat and carbon, buffering the pace of atmospheric warming. This study combined satellite observations with direct ocean measurements to track changes in AABW across the Southern Ocean between 2002 and 2023. It found that AABW volume has steadily declined since 2002, with the rate of loss increasing about fourfold after 2015. This loss closely coincides with the sharp decline in Antarctic sea ice that began in 2016, with the study finding a strong relationship between sea ice extent and AABW volume. The findings suggest that ongoing changes in Antarctica are already altering the structure and circulation of the deep ocean. Continued losses of AABW could reduce the ocean’s ability to store heat and carbon, with implications for global ocean circulation, sea level, and climate.

纸 | News Coverage by the Australian Antarctic Program Partnership (AAPP)