Actually the Greenland Ice shelf is thousands of years old, and the vast majority of the land under the ice is permafrost. Whonamed the Island Greenland? Erik the Red, I'll bet he wasn't "red". He was also in exile, and what would you name an island if you wanted to attract followers, Frozen chunk of Ice Island?
Just thought I'd add to the original post, that IPCC acknowledged their models had underscored the ice retreat, the reason being they use many global models, which will be more conservative in the estimates than a regional model like this study.