The Late Freeze

Landfast sea ice — the ice that attaches to the coast and stays put through winter — is disappearing along Alaska's Arctic shores faster than expected. A 2026 study in Journal of Geophysical Research: Oceans (Mahoney et al., University of Alaska Fairbanks) extended a 2014 dataset through 2023 and found the landfast ice season has shrunk by 57 days in the Chukchi Sea and 39 days in the Beaufort Sea since 1996.

The loss is asymmetric. Most of the shrinkage comes from later formation, not earlier breakup. Air temperatures drop below freezing on schedule in autumn, but the ocean stays warm longer. Thermal inertia in the water delays the onset of ice formation by weeks. The same air temperature that once froze the sea in October now doesn't freeze it until December because the ocean absorbed more heat during a longer ice-free summer.

Landfast ice is not the same as the sea ice that climate reports typically discuss. Sea ice extent — the metric in the Arctic record-low headlines — measures the total area of ocean covered by ice, mostly offshore pack ice. Landfast ice is the narrow band of ice anchored to the coast. It's what coastal communities walk on, hunt from, and rely on to buffer their shorelines from winter storms. Its loss doesn't change the Arctic sea ice extent number much, but it changes everything for the people who live there.

The feedback is local and immediate. Without landfast ice, winter storm waves reach the coast unobstructed. Permafrost bluffs that were protected by a buffer of shore-fast ice now erode directly. Some Alaskan villages — Shishmaref, Kivalina, Newtok — have already begun relocation planning because the coast is retreating faster than infrastructure can be maintained.

The measurement gap matters: global sea ice metrics don't resolve the landfast component. A winter with average total extent can still have catastrophically late landfast formation. The people who depend on the ice are invisible in the aggregate statistic.