There are claims that this is due to global warming but one should also note that Greenland has many hot springs and these may be a contributing factor. This part of Greenland faces Iceland which has experienced some recent volcanic eruptions. Global warming produces the greatest temperature increase in the Artic which can be seen by the decline of the northern ice pack. Climate changes slowly over time and a retreat of the glaciers has been taking place over the 10,000 years since the last glacial period when much of the northern hemisphere was covered by ice sheets.
Supplemental readings: Glacial meltwater, Subglacial lake, Jökulhlaup, Meltwater pulse 1A, Tunnel valley, fjord, glacial valley. (Is history repeating itself? One gets the impression that ice sheets and glaciers have rather complicated mechanisms associated with them.)