Low temperatures, wind-chill, snow, sea ice, and permafrost have been primary characteristics of Canada's northern and alpine environments during the past two million years. The evolution of Canada's cultural landscapes, the processes of settlement of rural areas, and the present interaction of Canadian industrial society with its biophysical environment are all deeply influenced, directly or indirectly, by the frigidity of the greater part of the country. The phenomenon of global warming, if it occurs, will lessen this coldness, but its impact on temperature extremes, sea ice regimes, vegetation, snow distribution, permafrost, glaciers, lakes, rivers, and mountain hazards are all the subject of intensive research -- the highlights of which are reviewed in Canada's Cold Environments.