With an axial tilt of 23.5 degrees, the poles of the earth enjoy no direct sunlight for several months each year. It would be sensible to conclude, like winter in the lower portions of the earth’s latitudes, that the extended direct sunlight it receives during the rest of the year would warm and reverse the cooling effect caused by little sunlight, but it can’t for several reasons which all contribute to climactic temperatures near or below freezing year round.
While gravitational tides from the sun and moon and geothermal events inside the earth itself all provide some heating, the overwhelming majority of earth’s heat comes form the nuclear furnace at the center of our solar system, the sun. The first factor in the travel of this radiant energy is how much atmosphere it must penetrate to reach the surface. Except for the height of summer, the radiation must travel much further through air to reach the poles, diluting its warming effect.
Not only do the poles receive less of the sun’s energy than the lower latitudes, they retain very little of it because of reflection from snow, the lack of rock exposed to the sunlight and atmospheric considerations that do not hold in heat. Even melted snow heats up slowly when there are large amounts of water compared to the same surface area of rock or land.
Of particular interest is the ocean currents which could, under certain conditions, provide warm water to counter the overall freezing effect. At the south pole, the Antarctic continental land mass prevents this potential circulation. At the north pole, it is a combination of landmasses around the Arctic Sea: Asia, Europe, North America and the large island of Greenland. Physics from the convection effect of currents from the warmer areas around the equator also factor in. The warmer sea water, being denser, sinks when it encounters cooler fresh water and is forced to a lower level below the sea and begins its return toward the equator. The further south this sinking effect creeps into the Atlantic, the more likelihood that traditionally mild European climate will turn significantly cooler and become very hazardous for the population of Europe.
Even in the face of advancing climate change, the poles are likely to remain frozen over through the year for many thousands of years yet. The ability to capture and retain enough heat is not present in its geographic circumstances.