Land and Sea Distribution
The distribution of land and water is a factor with important implications for climate. Because water has a higher heat capacity than land and so exhibits a greater resistance to temperature change than does a land area (that is it has greater thermal inertia), land heats up more during the day and in summer, and cools down more at night and during winter than do adjacent bodies of water. This means that localities immediately adjacent to water exhibit smaller seasonal temperature variations than do localities that are situated well inland. For example, continental conditions cause the climate to be quite severe in the interior of northern Russia and Canada. The "Cold Pole," or coldest part of the Northern Hemisphere, is in northeast Siberia near Verkhoyansk.
The Arctic consists of an ocean surrounded by land, and the ocean has a warming influence on the land. However, because a large part of the Arctic Ocean is covered by an insulating layer of ice, the warming influence of the ocean in winter is decreased. Leads and polynyas (cracks and open areas in the ice) permit intense heat exchange from the water to the atmosphere during the cold part of the year because of the large differences between the air and water temperatures. But overall, the influence of the ocean in moderating local climate where sea ice is present is much less in winter than in summer. In Norway, where open water persists all year, the moderating effect of the ocean is largest in winter.
Ocean Currents
Ocean currents bring warm water, and thus heat, from low latitudes to the northeastern part of the Atlantic Ocean with the result that some places that are geographically part of the Arctic, such as northern Norway, do not experience the full severity of an arctic climate.
In the Atlantic, warm, high-salinity water flows northward in the Gulf Stream along the east coast of North America. Some of this water continues northeastward in the North Atlantic Current toward Iceland and Norway. Off the coast of Greenland, a portion of the surface water cools, becomes dense, and sinks. A further portion of surface water continues into the Arctic Ocean before also cooling and sinking. Together these sinking plumes off Greenland and in the Arctic form "deep water" that plays an important role in global oceanic circulation. The effect of the annual growth and retreat of sea ice on the formation of deep water, and the nature of the processes that modify Atlantic water entering the Arctic ocean, are areas of active research. The figure below shows the major features of North Atlantic and Arctic Ocean circulation.
A schematic drawing of North Atlantic and Arctic Ocean circulation. Red arrows represent relatively warm water from lower latitudes entering the Arctic, while blue arrows represent the export of colder water from the Arctic. Shaded white shows the average area covered by sea ice. (Figure courtesy of G. Holloway, Institute of Ocean Sciences, Sidney, British Columbia. For more information see http://www-sci.pac.dfo-mpo.gc.ca/osap/projects/jpod/).