Fred D. Richards, Sophie Coulson, Mark Hoggard, Jacqueline Austermann, Blake Dyer , Jerry X Mitrovica

The Mid-Pliocene represents the most recent interval in Earth history with climatic conditions similar to those expected in the coming decades. Mid-Pliocene sea-level estimates therefore provide important constraints on projections of future ice-sheet behaviour and sea-level change, but differ by tens of metres due to local distortion of paleoshorelines caused by mantle dynamics. Here, we combine an Australian sea-level marker compilation with geodynamic simulations and probabilistic inversions to quantify and remove these post-Pliocene vertical motions at continental scale. Dynamic topography accounts for most of the observed sea-level marker deflection, and correcting for this effect and glacial isostatic adjustment yields a Mid-Pliocene global mean sea level of +16.0 (10.4– 21.5) m (50th/16th–84th percentiles). Recalibration of recent high-end sea-level projections using this revised estimate implies a more stable Antarctic Ice Sheet under future warming scenarios, consistent with mid-range forecasts of sea-level rise that do not incorporate marine ice cliff instability.