The Cryosphere, 5 May 2022

Arctic sea ice plays a crucial role in protecting the Alaskan coastline from open ocean waves generated in the Beaufort Sea. Seasonal sea ice forms near the shore during the fall, gradually merging with the thicker multi-year ice to create a layer across the surface that dampens the waves underneath. During the winter, this sea ice cover prevents waves from reaching the coastline. Rising air and ocean temperatures delay the formation of the sea ice cover and accelerate its melting, which allows waves to gain more momentum and height. Over the past forty years, the “open-water” season – the warm period each year without the seasonal sea ice cover – has lengthened by more than three months, which has resulted in a 5-fold increase in annual wave power. Moreover, the lengthened sea ice-free period increases the vulnerability of the Alaskan coastline to rough waves generated during fall storms with high wind speeds. On average, there were only one or two “rough wave” days per year during 1979; now there are more than two weeks annually. Sea ice cover has been decreasing across the Arctic basin for the past two decades, with the largest decline occurring across the Beaufort Sea and Chukchi Sea coasts. These findings underscore the importance of reducing emissions to maintain Arctic sea ice cover and protect Alaskan coastlines from erosion and collapse.