Geodynamically corrected Pliocene shoreline elevations in Australia consistent with midrange projections of Antarctic ice loss

Fred D Richards; Sophie L Coulson; Mark J Hoggard; Jacqueline Austermann; Blake Dyer; Jerry X Mitrovica

doi:10.1126/sciadv.adg3035

Geodynamically corrected Pliocene shoreline elevations in Australia consistent with midrange projections of Antarctic ice loss

Sci Adv. 2023 Nov 15;9(46):eadg3035. doi: 10.1126/sciadv.adg3035. Epub 2023 Nov 17.

Authors

Fred D Richards¹, Sophie L Coulson^{2

3}, Mark J Hoggard⁴, Jacqueline Austermann⁵, Blake Dyer⁶, Jerry X Mitrovica⁷

Affiliations

¹ Department of Earth Science and Engineering, Imperial College London, London, UK.
² Fluid Dynamics and Solid Mechanics Group, Los Alamos National Laboratory, Los Alamos, NM, USA.
³ Department of Earth Sciences, University of New Hampshire, Durham, NH, USA.
⁴ Research School of Earth Sciences, Australian National University, Canberra, ACT, Australia.
⁵ Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY, USA.
⁶ School of Earth and Ocean Sciences, University of Victoria, Victoria, BC, Canada.
⁷ Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA, USA.

Abstract

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 behavior and sea level change but differ by tens of meters due to local distortion of paleoshorelines caused by mantle dynamics. 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 to +21.5) m (50th/16th to 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 midrange forecasts of sea level rise that do not incorporate a marine ice cliff instability.