Enhanced Arctic sea-ice retreat due to pronounced pacificization effect in the Holocene

Abstract

Future climate confronts major challenges due to ongoing Arctic sea-ice retreat. Notably, eventful sea-ice loss in the Holocene appears comparable circumstance, but associated physics remians poorly understood. Here we present a high-resolution and semi-quantitative reconstruction of sea-ice conditions over the East Siberian Arctic Shelf. A compilation of sea-ice reconstructions across the circum-Arctic characterizes a Pacific-side Arctic sea-ice melting event between 4.5 and 2.2 ka BP. Together with basin-wide paleoclimate records, satellite-derived and numerical modeling datasets, we attribute this sea-ice melting event to enhanced Bering Sea Inflow with stronger poleward transport of Pacific oceanic heat, which overcame long-term Holocene cooling trend likely linked to concurrently slowing Atlantic Meridional Overturning Circulation. Such Holocene-scale competition effect of ‘Pacificization v.s. Atlantification’ may conceptually explain the modern dipole pattern in Arctic sea-ice variation. In the warming future, projected more frequent La Niña circumstance could indicate enhanced Pacificization effect, leading to aggravated Pacific-side Arctic sea-ice retreat.