I can understand that the thickness of the ice will vary with the seasons and more generally over the years, but as I understand it, much of Greenland has not been accurately surveyed, and I don't think the MSA will vary at all, as the ice thickness will not vary by 100's of feet. The published MSA's I would assume account for annual variations and fudge factors where surveys are incomplete.
What I think you may be confusing is the MEA (minimum enroute altitude) or MOA (minimum operating altitude), both of which will adjust the MSA for temperature and wind strength factors.
The latest chart I have to hand suggests the MSA peaks at about 15600 generally in the north.