Breaking the Ice: Exploring the Changing Dynamics of Winter Breakup Events in the Beaufort Sea

The Beaufort Sea has experienced a significant decline in sea ice, with thinner first-year ice replacing thicker multi-year ice. This transition makes the ice cover weaker and more mobile, making it more vulnerable to breakup during winter. Using a coupled ocean-sea-ice model, we investigated the impact of these changes on sea-ice breakup events and lead formation from 2000 to 2018. The simulation shows an increasing trend in the Beaufort Sea lead area fraction during winter, with a pronounced transition around 2007. A high lead area fraction in winter leads to greater growth of new, thin ice within the Beaufort region while also leading to enhanced sea ice transport out of the area. Despite the large export, consisting primarily of thinner first-year ice, we find little evidence that winter breakup amplifies the advection of multi-year ice from the central Arctic into the Beaufort Sea. Overall, the export offsets ice growth, resulting in negative volume anomalies and preconditioning a thinner and weaker ice pack at the end of the cool season. Our results indicate that large breakup events may become more frequent as the sea-ice cover thins and that such events only became common after 2007. This result highlights the need to represent these processes in global-scale climate models to improve projections of the Arctic. The sea ice cover in the Beaufort Sea has been changing - it is getting thinner and weaker. This makes the ice more likely to break apart from strong winds. Using a computer model, we study how these changes may have affected the frequency of large sea-ice breakup events from 2000 to 2018. We find that the amount of open areas in the sea ice, called leads, is increasing during winter. This allows new, thin ice to form, but also causes more ice to move out of the region under the action of winds and currents. This movement of ice cancels the growth of new ice, resulting in less ice overall at the end of winter in this region. Interestingly, these events became more common after 2007 and the results suggests that bigger breakup events might happen more often as the sea ice continues to thin. This study highlights how important it is to include these changes in large climate models to better predict what might happen in the Arctic in the future. Modeled changes in Beaufort Sea ice conditions from 2000 to 2018 contribute to an increase in lead frequency and sea ice breakup in winter Winter breakup increases ice export from the Beaufort Sea and leads to a thinner and weaker ice cover at the end of the cool season The enhanced ice export has no clear effect on the flushing of multi-year ice from the Central Arctic into the Beaufort Sea