The geographical proximity of Iceland and Greenland, both located at similar high northern latitudes, suggests they should share a comparable climate. However, Iceland boasts a subpolar oceanic climate with relatively mild winters, while Greenland is largely covered by a permanent, frigid ice sheet. This stark difference in temperature and habitability is a result of a powerful interplay between global ocean currents, continental ice mass, and regional atmospheric circulation. The mechanisms that deliver warmth to Iceland are precisely those that are blocked or overwhelmed by the vast, cold presence of Greenland.
The North Atlantic Current’s Warming Effect
The primary factor responsible for Iceland’s moderate climate is the North Atlantic Current, a powerful extension of the Gulf Stream system. This current acts as a heat conveyor belt, transporting immense volumes of warm, saline water from the tropical and subtropical Atlantic northward. As this warm water flows toward Iceland, it constantly releases thermal energy into the overlying atmosphere, significantly moderating the air temperature.
The effect of this oceanic heat transfer is substantial, making Iceland’s winter temperatures far milder than other locations at the same latitude. For instance, the average temperature near Iceland’s southern coast often hovers around \(1^\circ\text{C}\) in winter. The current also ensures that the surrounding ocean remains largely free of sea ice, maintaining open shipping routes and preventing the frigid conditions associated with a frozen sea surface.
The Massive Role of Greenland’s Ice Sheet
In sharp contrast to Iceland, Greenland’s immense size and permanent ice cover create a massive, self-sustaining cold climate. The Greenland Ice Sheet covers about 80% of the landmass, creating an elevated continental dome that reaches elevations over 3,000 meters. This high elevation contributes to adiabatic cooling, where the air temperature naturally decreases with altitude, keeping the interior profoundly cold.
The most powerful cooling mechanism is the albedo effect. Snow and ice have a very high albedo, meaning they reflect a large percentage of incoming solar radiation back into space instead of absorbing it as heat. Fresh snow can reflect up to 80% of the sunlight, effectively preventing the surface from warming. This continuous reflection maintains extremely low temperatures year-round, reinforcing the presence of the ice sheet and resisting any warming influence from the ocean.
Prevailing Air Masses and Wind Patterns
The final element involves the prevailing atmospheric circulation, which distributes the warmth from the ocean and the cold from the ice sheet. The North Atlantic is dominated by the Icelandic Low, a persistent low-pressure center that helps steer weather systems. This low-pressure area, combined with the general flow of westerlies, ensures that air masses are frequently carried from the southwest toward Iceland.
These westerly winds carry the warm, moisture-laden air heated by the North Atlantic Current directly over Iceland, reinforcing the oceanic warming effect. Conversely, Greenland’s colossal ice sheet generates its own dome of dense, frigid air. This cold, heavy air frequently flows outward from the interior across the coasts, bringing significantly lower temperatures to the areas surrounding Greenland.