Abstract This study presents a high‐resolution reconstruction of the Antarctic Intermediate Water (AAIW) transport variability on the southeastern Brazilian continental margin over the last 16,000 years BP, based on grain‐size analysis. Variations of sortable silt () are interpreted as changes in flow speed of the Intermediate Western Boundary Current (IWBC), the primary pathway for northward AAIW transport along the western South Atlantic. Enhanced values during the Younger Dryas suggest intensified IWBC flow, while reduced values during the Bølling–Allerød indicate weaker transport. These patterns reflect the sensitivity of AAIW/IWBC dynamics to millennial‐scale climate fluctuations, supporting an interhemispheric seesaw mechanism. The integration of sortable silt data with grain‐size end‐member modeling provides new insights into changes in intermediate‐depth circulation in the Southwest Atlantic and their connection to climate reorganizations. This work emphasizes the critical role of AAIW in past ocean–climate interactions and highlights the importance of high‐resolution reconstructions.
Sambugaro et al. (2026) studied this question.