ISOTIPIC: Greenland ice sheet potential for tipping with the Earth System Model UKESM-ice

As part of a project exploring the relation between the Greenland ice sheet stability and the AMOC, we present coupled climate and ice sheet simulations of Greenland with the Earth System Model (ESM) UKESM, a state-of-the-art ESM capable of representing the interactions between ice sheets and the atmosphere and their co-evolution (UKESM-ice; Smith et al., 2021). Recent large ensemble exercises indicate that there is no sign of non-linear volume change or irreversibility at the scale of the Greenland ice sheet in UKESM-ice, even at high warming levels and despite large ice losses. We present new simulations exploring Greenland's potential for tipping with modified (snow and ice sheet) parameters and including a recently developed scheme for the marine forcing of outlet glaciers, which was previously omitted from UKESM-ice and prevented the representation of the direct influence of the ocean on the Greenland ice sheet. Results show linear trends of (large) ice volume change at the scale of the ice sheet but local evidence of accelerating melt along the South West margin. Next steps in the project include providing fresh water from UKESM-ice surface runoff and solid discharge of icebergs to investigate their effect on the strength of the AMOC in NEMO simulations and using a new high resolution NEMO dataset as ocean forcing of the ice sheet in UKESM-ice.