Comment on "exceptionally high heat flux needed to sustain the Northeast Greenland Ice Stream" by Smith-Johnsen et al. (2020)

Smith-Johnsen et al. (The Cryosphere, 14, 841-854, 2020) model the effect of a potential hotspot on the Northeast Greenland Ice Stream (NEGIS). They argue that a heat flux of at least 970 mW m-2 is required to have initiated or to control NEGIS. Such an exceptionally high heat flux would be unique in the world and is incompatible with known geological processes that can raise the heat flux. Fast flow at NEGIS must thus be possible without the extraordinary melt rates invoked in Smith-Johnsen et al. (2020).