Dynamic Greenland ice sheet driven by pCO variations across the Pliocene Pleistocene transition.

It is generally considered that the perennial glaciation of Greenland lasting several orbital cycles began around 2.7 Ma along with the intensification of Northern Hemisphere glaciation (NHG). Both data and model studies have demonstrated that a decline in atmospheric pCO was instrumental in establishing a perennial Greenland ice sheet (GrIS), yet models have generally used simplistic pCO constraints rather than data-inferred pCO evolution. Here, using a method designed for the long-term coupling of climate and cryosphere models and pCO scenarios from different studies, we highlight the pivotal role of pCO on the GrIS expansion across the Plio-Pleistocene Transition (PPT, 3.0-2.5 Ma), in particular in the range between 280 and 320 ppm. Good qualitative agreement is obtained between various IRD reconstructions and some of the possible evolutions of the GrIS simulated by our model. Our results underline the dynamism of the GrIS waxing and waning under pCO levels similar to or lower than today, which supports recent evidence of a dynamic GrIS during the Plio-Pleistocene.