Why Icebergs and their Interactions with Sea Ice Should Be Included in Earth System Models?

Thirty-three researchers from France, Australia, Belgium, Canada, the UK, and Germany gathered in Paris for a two-day hybrid workshop (3–4 June 2025) to discuss iceberg–sea ice interactions and their representation in Earth system models. Icebergs and sea ice are two distinct forms of drifting ice, typically represented usingdifferent modelling approaches. Icebergs — relatively small in horizontal extent (500 m - 50 km long) but up to 700 m thick — calve from continental ice shelves and marine terminating glaciers and are modelled as Lagrangian particles. In contrast, sea ice, forming from the freezing of seawater, covers vast areas, spanning thousands of kilometers, but is much thinner (about 1 m thick), and modelled as a two-dimensional continuum. Current Earth system models generally assume that sea ice–iceberg interactions are negligible. However, mounting evidence indicates that processes essential to Antarctic sea ice and ocean dynamics — such as landfast sea ice and coastal polynyas — arise from dynamic iceberg–sea ice interactions. Several Earth system modeling groups are actively addressing these interactions, resulting in a series of recent studies on icebergs, sea ice, and their interplay, which motivated the workshop.Presentations from 13 invited speakers, covering modelling and observational perspectives, formed the basis of discussions around the following themes:- Iceberg, sea ice, and their interactions; - Implications for the ocean; - Perspectives on numerical and computational model infrastructure.