What is a polar ice cap?
High latitude regions of a planet or a moon which are covered with snow are called polar ice caps. In case of our own planet: the northern and the southern poles are where the ice caps are located and it is only a coincidence that our polar ice caps are at the poles. The definition doesn’t mandate them to be at the poles.
It is not necessary that one would always find water-ice there. For example, it has been discovered that the polar ice caps on Mars hold carbon dioxide gas in solid form in addition to the water ice.
How do they form and melt?
At higher latitudes, the earth doesn’t receive much sunlight and, therefore the temperatures remain low for most part of the year, thus the water can’t remain in liquid form and it solidifies i.e. turns into ice.
Geological variations and seasonal changes also affect the sizes of polar ice caps. On our planet the ice of the North Pole occupies an area of 9-12 million square kilometers, depending upon what time in the year one is taking measurements. Antarctica is bigger, with and its size being about 14 million square kilometers.
When it comes to melting, there are three main causes:
The causes for these changes can be explained by Milankovitch Cycles. The cycles proposed by him take into account orbital shapes (eccentricity), axial tilt (obliquity), axial precession, apsidal precession and orbital inclination.
All these factors, when combined, affect the conditions on the planet in the long term and it causes ice ages at different times. During an ice age the ice caps increase in size and they retreat when an ice age ends. These changes occur over a period ranging from thousands to millions of years.
They are medium-term changes and they occur every year. Every year with the coming of the winter season, the ice caps begin to expand but they melt again with the coming of the summer seasons.
It is the most controversial of all reasons. Some say the carbon emission from our cars, airplanes, rockets etc are the root cause while others argue these acts are too insignificant to change the course of how nature works.
Effects of melting:
If the ice on the polar ice caps were to melt, the resulting consequences wouldn’t be good for the most of the living species here. Here are a couple of facts:
(1) We would lose species like penguins and polar bears that rely on snow for their lives.
(2) The sea-levels would rise resulting in an increase in the sea-levels.
(3) The polar ice caps reflect sunlight, if they melted, the earth would receive more sun-light and would become warmer.
(4) The melting of the glacier could cause riots and civil wars in poor countries which lie along the sea coasts.