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Sea ice ecosystems

Polar bears which depend on sea ice for many aspects of their life history are particularly vulnerable to the effects of habitat loss. Fot. Wojtek Walkusz

Sea ice covers some 3-7% of the total surface of our planet depending on the season of the year . Apart from being one of the most important climatic variables and key indicator of climate change, sea ice also provides an extreme and changeable habitat for diverse sympagic organisms, which play an important role in the ecosystems of the polar seas.

Sea ice cover occurs primarily in the polar regions, but in the northern hemisphere it may be also found at lower latitudes (eg. in the Baltic, Caspian and Okhotsk seas, the Gulf of St. Lawrence, Scandinavian fjords). Land-fast ice forms and remains fast along the coast, attached to the shore or grounded to a shallow sea bottom. Pack ice refers to any area of floating sea ice that is not land-fast.