Vellur! My friend... how long an explanation do you expect! The Sun contains sufficient energy in the form of heat to melt every living soul and non living entity on the earth!
The ozone layer on the earths stratosphere protects us as it refines the intensity of rays of the sun... reflecting back the UV content!
However due to some of man's endeavors, global warming has taken place resulting in ozone depletion in certain regions! This has depleted the protective coating and some of the earth's parts have been exposed to Sun's UV radiation!
So the polar caps have already started melting my friend... and water level is starting.
The answer in a nutshell to your question is " IT ALREADY HAS"