Freeze-up of Arctic Sea Ice in the U.S. Beaufort and Chukchi Seas (2014-2015)

The freeze-up studies (2009-10 through 2013-14) had established that air temperature alone cannot predict freeze-up timing and that continued monitoring was needed to track how landfast ice stability, the coastal flaw lead, and multi-year ice invasions were evolving relative to the 1980s baseline. This study was designed to document the 2014-15 freeze-up season in the Alaskan Beaufort and Chukchi Seas by locating and mapping ice features of interest and correlating ice movement with meteorological conditions and historical patterns. The study combined remote sensing, meteorological data, and aerial reconnaissance to describe ice conditions and quantify changes relative to the 1980s dataset. The 2014-15 winter was exceptionally warm, ranking as the second warmest on record at Barrow and the warmest in six years at Deadhorse, and produced the thinnest first-year ice computed for the Beaufort in six winters (148 cm in both seas). Freezing-degree days at Barrow continue to decline at roughly 45 per year, with the greatest warming in October and November; freeze-up now occurs about three weeks later than the 1980s in the Beaufort and about one month later than the 1970s in the Chukchi; first-year ice thickness has fallen by over 10% since the early 1980s, likely compounded by increased insulating snowfall; and while landfast ice west of Prudhoe Bay and the Chukchi flaw lead's frequency remain comparable to historical patterns, a stable shear zone east of Prudhoe Bay and large multi-year ice invasions in both seas have both become substantially less likely than in the 1980s. Pack ice in the Beaufort continues to drift at rates (about 5.5 nm/day) consistent with historical values. This abstract was drafted with the assistance of Claude, July 2026.