Proxy data compiled for Antarctica, the Southern Ocean and the southern high latitudes spanning the Eocene and Oligocene. a) Map depicting location of records used in this study. b) Land surface mean air temperature (MAT) data including BayMBT (Tibbett et al., 2021a, 2022b), pollen climate reconstructions including NLR (Amoo et al., 2022; Francis et al., 2008; Macphail & Truswell, 2004; Passchier et al., 2013; Poole et al., 2005; Thompson et al., 2022; Truswell & Macphail, 2009), S-index (Passchier et al., 2013, 2017), and MBT/CBT (Douglas et al., 2014). c) Sea surface temperature (SST) data from BAYSPAR calibrated TEX86 data (Douglas et al., 2014; Hartman et al., 2018; Houben et al., 2019; Lauretano et al., 2021; Pagani et al., 2011), SSTs from BAYSPLINE calibrated Uk’37 (Houben et al., 2019; Liu et al., 2009; Pagani et al., 2011; Plancq et al., 2014), and Δ47 from bivalves (Douglas et al., 2014; Petersen & Schrag, 2015). d) Air Temperature anomaly and e) sea surface temperature anomaly for each Southern Ocean sector with data normalized by the respective datasets Eocene mean in standard deviation units (Z scores), combined for each Southern Ocean sector, and then interpolated to a common interval with a spline fit to the data. Only datasets covering the late Eocene and early Oligocene were used for the temperature anomaly plot. f) δ18Obenthic spline (Westerhold et al., 2020) and pCO2 compiled from δ11B (blue) and alkenone (red) proxies (Rae et al., 2021).