Sea ice is thought to be a principal player in Dansgaard-Oeschger (D-O) cycles, the millennial scale climate cycles that are a prominent feature of North Atlantic paleoclimate records throughout much of the last glacial period. Although some observational evidence exists to support this idea, it is not sufficient to constrain the exact characteristics of or mechanisms behind sea ice displacements during D-O cycles. This presentation will provide an overview of modelling experiments and high-resolution data records from the Nordic Seas aimed at resolving some of these open questions.