Assessing Arctic marginal ice zone dynamics from 1979 to 2023: insights into long-term variability and morphological changes

Abstract Against the backdrop of global climate change, the continued decline in Arctic sea ice extent and thickness has intensified the dynamic evolution of the marginal ice zone (MIZ). As a critical transitional region between the open ocean and pack ice, the MIZ plays a pivotal role in mediating ocean-atmosphere interactions, influencing sea ice dynamics, and supporting polar ecosystems. This study investigates the dynamic variability and morphological evolution of the Arctic MIZ from 1979 to 2023 using the Bootstrap sea ice concentration (SIC) product. Results reveal that while the overall MIZ extent has remained relatively stable over the long term, the MIZ fraction (i.e. the ratio of MIZ extent to Arctic sea ice extent) has increased significantly, as the total sea ice extent has decreased over time. The seasonal cycle is pronounced, with minimum extents observed in March or April and maximum extents in August or September. From June to September, the SIC values within the MIZ showed a significant downward trend in spatial distribution, indicating that the SIC in this region generally decreased during summer. Furthermore, the MIZ has experienced a northward shift over the past four decades, with an accelerated rate of migration post-2000. This shift is accompanied by morphological changes, characterized by a smoother ice edge and more compact ice during late summer. A significant change point was detected in 2006, signaling a structural shift in MIZ dynamics. Post-2006, the frequency of MIZ occurrence increased in high-latitude regions, particularly across the Beaufort, Chukchi, East Siberian, and Laptev Seas. These findings provide critical insights into Arctic sea ice dynamics, highlighting the evolving nature of the MIZ and its role in shaping the future Arctic ice regime under continued climate change.