KEY FINDING 7. Declining extent and thickness of sea ice, warming and thawing of permafrost, accelerating loss of glacier mass, and shortening of lake-ice seasons are detected across Canada’s biomes. Impacts, apparent now in some areas and likely to spread, include effects on species and food webs.
Ice is a defining feature of Canada’s ecosystems – permafrost (frozen ground) underlies almost half the country. Arctic sea ice (increasingly seasonal) extends across the North and along parts of the east coast and most Canadian lakes and many rivers are seasonally frozen. Outside of the huge ice sheets of Antarctica and Greenland, Canada has the largest area of glaciers in the world (200,000 km2), of which 75% is in the Arctic Archipelago.1
Ice ecosystems are important because they provide critical habitat for species adapted to living in, under, and on top of ice – from tiny one-celled organisms that live in the network of pores and channels within ice to polar bears. Sea ice helps regulate ocean circulation and air temperatures. Timing and duration of ice cover on rivers, lakes, and the sea are important factors in the types of plant and animal communities that water bodies support. Glaciers store fresh water and feed many of Canada’s largest rivers. Permafrost stores carbon and influences the structure of the landscape and storage and flow of water.