For Alaska Native peoples living in coastal communities, sea ice is critically important. Many Arctic animals (such as polar bears, walruses, and seals) use sea ice as a platform for hunting, resting, feeding, and transportation, and therefore it also serves as an important platform for subsistence hunters. In addition, sea ice protects the shoreline from extreme coastal erosion: it reduces the erosive effects of wind, waves, and currents that wear away at the land and transport rock fragments and sand away from the shore.

Changes in sea ice affect the subsistence ways of life and future of many coastal communities in Alaska. Traditional knowledge about weather patterns and ice conditions has become less reliable due to the accelerated pace of climate change, making subsistence hunting more challenging and more dangerous. In addition, warmer average temperatures and the loss of sea ice result in a loss of habitat for animals; as a result, their health and reproductive success suffer. Furthermore, the later formation and decreased extent of sea ice leave the coast more exposed to damaging waves.

Ocean waves are the primary agent of coastal erosion. The larger and more energetic the wave, the greater its erosive effects; storm surges and tidal highs are especially damaging. Open water provides a large fetch area—the distance over which wind blows to create waves—which allows the development of especially large and powerful waves. Sea ice reduces fetch and acts like a lid on the water to limit wave size, reducing wave energy and erosion. The warming climate reduces the protective barrier of sea ice and also thaws permafrost, which can further exacerbate coastal erosion. As the ice in the permafrost thaws, the land subsides and weakens and becomes more vulnerable to destruction by wave action.

Damage from erosion places property and the safety of people at risk. Several coastal villages in Alaska are facing an uncertain future as a result of dramatic coastal erosion. For example, the people who live in Shishmaref, a traditional Iñupiaq village on a small barrier island on the Chukchi Sea, are now being forced to relocate. Many residents have already moved their homes along the coast to other parts of the island. However, as the island continues to erode, it will soon be too dangerous for anyone to remain there. Eventually, the entire community of Shishmaref will need to relocate. Residents hope to relocate the village to a nearby location on the mainland. While the new location will still be accessible to the sea and continue to protect the community's subsistence ways of life, the psychological, cultural, and financial costs of the planned move are substantial.

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