That's a very carefully written piece that makes a good effort on sparse data. Basal sliding and deformation of subglacial till, as discussed earlier for Jakobshavn, need a thawed bottom. This is not anything brought about or exacerbated by contemporary climate change but rather an inconvenient legacy condition that, unfortunately, would synergize with global warming above to raise sea level faster than a frozen legacy condition would have.
Although sidd already posted the bottom line (Fig.11), Table 1 provides a very useful compendium of known basal temperature data.
There's also a curious analysis of surface texture based on the MODIS mosaic of Greenland (MOG) said to delineate the ice sheet transition between a relatively smooth surface and prominent surface undulations corresponding to relative velocities and so presumably to basal melt status. Yet though shear margins of NEGIS are well defined its route is not distinguished by surface undulations and some adjacent regions don't fit the roughness paradigm. Fig.9 shows this below.
There don't seem to be an immediate prospects for resolving the status of uncertain areas, not plausibly by a massive drilling grid on the flanks because ice cores are more favorable on summit ridges even though these don't have representative bottom conditions. Coring is underway this summer about a third of the way down NEGIS (good twitter site); however no one is laying out exactly what they expect to find by way of temperature profile prediction or rates of bore hole deformation.
The 'companion' article of April 2016, treated neutrally by Macdonald et al, asserts that the anomaly of NEGIS is explained by northeastern Greenland warmed from below tens of millions of years prior by anomalous mantle heat associated with the Iceland hot spot.
There is no chain of islands or bathymetry otherwise indicative of a hot spot track; the North Atlantic initially began to open in Baffin Bay where older basaltic flows are still evident but the subsequent forking history and mid-Arctic Ocean stalling of the Gaekel Ridge are still in a state of scientific confusion (in my view).
Melting at the base of the Greenland Ice Sheet explained by Iceland hotspot history
I Rogozhina, AGPetrunin ... 2016
Nat. Geosci., 9, 366–369, doi:10.1038/ngeo2689 paywalled
https://www.sciencedaily.com/releases/2016/04/160404111603.htmIce-penetrating radar and ice core drilling have shown that large parts of the north-central Greenland ice sheet are melting from below. It has been argued that basal ice melt is due to the anomalously high geothermal flux that has also influenced the development of the longest ice stream in Greenland.
Here we estimate the geothermal flux beneath the Greenland ice sheet and identify a 1,200-km-long and 400-km-wide geothermal anomaly beneath the thick ice cover. We suggest that this anomaly explains the observed melting of the ice sheet's base, which drives the vigorous subglacial hydrology and controls the position of the head of the enigmatic 750-km-long northeastern Greenland ice stream.
Our combined analysis of independent seismic, gravity and tectonic data implies that the geothermal anomaly, which crosses Greenland from west to east, was formed by Greenland's passage over the Iceland mantle plume between roughly 80 and 35 million years ago.