Well, first consider this: 70.9% of this planet is covered in World Ocean which is approx. 139.7 MILLION square miles.....
The island of Greenland is only 836,300 square miles with approx. 660,000 square miles of permanent ice which varies from only a few meters thick at the perimeter (which is constantly melting and freezing by the way) to a few thousand feet at the center and deepest point of the ice mass which will likely never melt do the average extreme cold.
With that being said, there isn't enough ice on Greenland to even raise the oceans a couple of feet if it were to all melt......and that ain't ever going to happen.
If the entire 2,850,000 cubic kilometres (684,000 cu mi) of ice were to melt, it would lead to a global sea level rise of 7.2 m (24 ft).[2] The Greenland Ice Sheet is sometimes referred to under the term inland ice, or its Danish equivalent, indlandsis. It is also sometimes referred to as an ice cap.