Modeling the Greenland ice sheet and Antarctic ice sheet during the mid-Piacenzian Warm Period

The mid-Piacenzian Warm Period (mPWP; 3.264 to 3.025 Ma) is a ~240 kyr long period with CO₂ concentrations between 350 and 530 ppmv, in the same range as in the middle of the road emission scenario SSP2-4.5 by 2100. Temperatures were between 2 and 5˚C above the pre-industrial state for a sustained period and as a result, sea-level high stands up to +17.2 m have been inferred. Taking into account a maximum contribution from thermal expansion of 1.6 m, the remainder should have been caused by (partial) melting of either the Greenland ice sheet (GrIS) or the Antarctic ice sheet (AIS), or both, as other ice sheets on the continents of the northern hemisphere were very likely absent.

Previous work has illustrated that the simulated GrIS and AIS size is strongly dependent on the applied climate -and ice sheet models. One way to constrain the ice sheet volume of the GrIS and AIS is by making use of the partition of the benthic oxygen isotope records in a terrestrial ice sheet component and a deep-sea temperature change component. Here we simulate various GrIS and AIS geometries based on available climate model output from the Pliocene Model Intercomparison Phase 2 (PlioMIP2) and compute the isotopic composition of the ice sheets. By selecting the ice sheet geometries that correspond best to the reconstructions for the terrestrial ice sheet component from the benthic oxygen isotope record, we further constrain the minimum GrIS and AIS extent during the mPWP.