"It's an alarming development," Khan said. "We do not know if it is due to global warming or other factors."
 
The researchers measured ice melt with Global Positioning Systems (GPS) stations located in the mountains and along the ice cap, which covers 1.7 million square km and is 3.2 km deep.
 
The measurements indicated that the mountains next to glaciers in the southeastern part of Greenland rose by four to five centimetres above the level of the icecap each year.
 
The banks of the glaciers thinned by 100 metres per year, the study said.
 
The study, which was made in conjunction with the US-based University of Colorado, was published in an online edition of Geophysical Research Letters magazine.