Fig. 2: Regions of intense interaction of the Antarctic Circumpolar Current with local bathymetry in Southern Ocean upwelling hotspots.

a Zonal variations in the percentage of upwelling particles transport crossing the 1000-m water depth surface (averaged between 30–70°S) as obtained in simulations with the Geophysical Fluid Dynamics Laboratory’s Climate Model version 2.6 (CM2.6)¹¹, where particles were released between 1–3.5 km water depth along 30°S. Increased particle transport in the simulations highlights five major topographic upwelling hotspots in the Southern Ocean¹¹. b Spatial changes in particle transport in percent across the 1000 m-depth surface, with vectors showing the average speed and direction of ocean currents at mid-depth (1–3.5 km) based on the Global Ocean Data Assimilation System (GODAS) database (https://psl.noaa.gov/data/gridded/data.godas.html) representing the Antarctic Circumpolar Current between 40–60°S. Squares indicate reconstructed deep-water ¹⁴C ages in the Southern Ocean during the last glacial maximum (LGM) referenced to preindustrial^10,16. Star in both panels shows the location of the study core. Figure modified after ref. ¹¹.