Arctic Marginal Ice Zone Variability: Area, Thickness, and Ocean Surface Links

The ongoing decline in Arctic sea-ice extent and thickness underscores the scientific importance of monitoring the marginal ice zone (MIZ), a transitional region between the open ocean and compact pack ice. As the Arctic continues to warm and summer sea-ice extent retreats, the MIZ has been widening and shifting poleward, providing clear evidence of an ongoing transition toward a new Arctic state. The MIZ plays a central role in atmosphere–ocean exchanges, with important implications for weather systems, marine ecosystems, and human activities. It is highly dynamic and characterized by strong spatial gradients and pronounced variability in sea-ice concentration, thickness, and ice composition.

Here, using global ocean reanalyses together with satellite products, we adopt an integrated ocean–ice perspective on the MIZ to identify robust indicators of the evolving Arctic climate state. We characterise Arctic MIZ properties in terms of area fraction and thickness, and their relationship with surface ocean conditions, and analyse the seasonal cycle and interannual variability of MIZ characteristics at hemispheric and regional scales from 1993 onward. Overall, our findings underline the importance of improving the understanding and representation of MIZ dynamics, ice-type distinctions, and coupled ocean–ice interactions to better constrain models and enhance projections of the future Arctic sea-ice cover.