Cold coasts may be defined as those where there is or has been abundant sea ice, lake ice, water-terminating glaciers or deeply frozen ground. Ice is important to both the geomorphological development of coasts and terrestrial and marine ecology in three main ways: as a moving entity, as a static phenomenon, and as a result of its phase changes between water and ice. Permafrost coasts are those where the landward side is underlain by frozen ground. Mostly, these coasts are affected by sea ice as well. Ice adds an extra dimension to geomorphological and ecological processes within these areas. The different forms of ice which so affect the geomorphological processes on cold coasts also affect the ecological processes. The future of cold coasts under conditions of global warming will depend largely on the response of the various forms of ice to climatic forcing.