Similarities and Differences in Arctic Sea-Ice Loss During the Solar-Forced Last Interglacial Warming (127 Kyr BP) and CO₂-Forced Future Warming

Based on a 7-member global circulation model ensemble from CMIP6/PMIP4, we compare the regional distribution of Arctic sea ice between a simulation representing the Last Interglacial (LIG) climate, with solar-forced warming, and an idealized future CO2-forced simulation with a similar annual sea-ice volume. The two simulations feature small but robust differences in the Central Arctic and Baffin Bay during summer, and larger differences at the sea-ice margins in the sub-Arctic Atlantic and North Pacific sectors during winter. Our results indicate that, under both forcings, sea ice persists north of Greenland until late summer, suggesting that the assumption that this region is the "Last Ice Area" is robust and holds for other climate states. However, we show that processes influencing sea-ice distribution in winter, such as Atlantification and sea-ice drift, differ and need to be further investigated.