Proxy‐Model Comparison for the Eocene‐Oligocene Transition in Southern High Latitudes

The Eocene-Oligocene transition (EOT) marks the shift from greenhouse to icehouse conditions at 34 Ma, when a permanent ice sheet developed on Antarctica. Climate modeling studies have recently assessed drivers of globally. Here we revisit those experiments for detailed study southern high latitudes in comparison growing number mean annual sea surface temperature (SST) and air (MAT) proxy reconstructions, allowing us assess proxy-model agreement refine estimates magnitude pCO2 forcing EOT. We compile update published records around Antarctica late Eocene (38–34 Ma) early Oligocene (34–30 Ma). Compiled SST proxies cool by up 3°C MAT 4°C between timeslices. Proxy data were compared previous climate model simulations representing pre- post-EOT, typically forced with halving pCO2. scaled outputs identify change needed drive commensurate best fit proxies. multi-model ensemble needs 30 or 33% decrease pCO2, respectively. These intercomparisons declining as primary EOT cooling, (200 243 ppmv) approaching that (150 ppmv). However individual span 66–375 ppmv, thus uncertainties are dominated divergence.