| Summary: | Variations in sea-ice cover result from a combination of changes in external forcing, internal variability and feedbacks. Due to the complexity of the interconnection between the mechanisms involved, the long-term evolution of the Arctic sea ice and its interaction with the ocean and atmosphere is not yet completely understood, leading to large uncertainties in climate projections. In this study, we focus on patterns of sea-ice cover loss in a context of past and future Arctic warming. Using a 7-member global circulation model ensemble from CMIP6/PMIP4, we compare the Arctic sea-ice distribution in a time-slice simulation representing the climate of 127 ka ago and an idealized greenhouse-warmed experiment with a similar annual sea-ice volume. The multi-model ensemble shows similar sea-ice loss patterns in the central Arctic but differences in the Atlantic sector. Under greenhouse-warmed conditions, there is generally more sea ice in south-east of Greenland compared to the Last Interglacial simulation, because of stronger northerly winds pushing ice towards this area. However, in the Barents Sea, the greenhouse warming causes more sea-ice loss than the solar warming. In this case, these is no clear role for the atmosphere. The Atlantic Water inflows are warmer and here we discuss the implication that Atlantification is stronger in the future than is has been during the Last Interglacial.
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