Supplementary Material S.1. Calendar age conversion The Drake Passage radiocarbon record of Burke and Robinson (2012) showed that values from sites in modern day AAIW had an average age offset from the atmosphere of 877 ± 235 years (SD, n = 11). We used this reservoir age for all corals in modern day AAIW (>200 samples from Burdwood Bank, including the station bathed in modern SAMW and seventeen from Cape Horn). For deep samples, located in modern day UCDW, the Burke and Robinson (2012) dataset showed a distinct shift from radiocarbon depleted (1660 ± 316 years SD, n = 7) to radiocarbon enriched (909 ±167 years SD, n = 24) waters at approximately 15 ka. The samples located in modern UCDW in this study were therefore divided into two sets, pre- and post-15 ka and the appropriate reservoir age was assigned. S.2. Figures Figure S1. Vertical depth profiles from sites close to our coral sampling sites produced using the Global Ocean Data Analysis Project (GLODAP) dataset in Ocean Data View (Key et al., 2004; Schlitzer, 2012) (a) temperature, (b) salinity, (c) oxygen and (d) aragonite saturation state. Burdwood Bank is represented by red dots, Cape Horn by yellow dots, Sars Seamount by purple dots, Interim Seamount by blue-green dots and Shackleton Fracture Zone as green dots. Total alkalinity and total CO2 data are scarce for aragonite saturation state calculations, and the only sites that measured both parameters close to coral stations are from Interim Seamount and one surface sample at Burdwood Bank. We also show a station south of the Subantarctic Front near Cape Horn measured both parameters, which is represented by black dots. Figure S2. Map of site locations where studies have utilized sediment cores to understand the paleoceanography of the Southern Ocean that are discussed in this paper. Cores are from Anderson et al., 2009 (red circles), Frank et al., 2000 (green circles), François et al., 1997 (orange circles), Howe and Pudsey, 1999 (pink circles), Kumar et al., 1995 (purple triangles), and Sachs and Anderson, 2000 (yellow circles). The Polar Front (APF_line – blue) and the Subantarctic Front (SAF_line – orange) are included along with the study region for this paper (red rectangle). Figure S3. Comparison of the number of corals collected (blue) versus the number dated (red) from the NBP08-05 and NBP11-03 cruises at sampling sites labeled Burdwood Bank (BB), Cape Horn (CH), Sars Seamount (SS), Interim Seamount (IS), Shackleton Fracture Zone (SFZ), considering only (a) D. dianthus, (b), Caryophyllia spp. All comparisons only include intact solitary corals. Figure S4. The number and composition of all collected intact solitary corals collected at (a) Burdwood Bank, (b) Cape Horn, (c) Sars Seamount, (d) Interim Seamount, (e) Shackleton Fracture Zone. References not included in text: Key, R.M., Kozyr, A., Sabine, C.L., Lee, K., Wanninkhof, R., Bullister, J.L., Feely, R.A., Millero, F.J., Mordy, C., Peng, T.H., 2004. A global ocean carbon climatology: results from Global Data Analysis Project (GLODAP). Global Biogeochem. Cycles 18 (4).