Fig. 5

Comparison between location of identified subglacial lakes and predicted lakes, geothermal heat flux, basal thermal state and bed roughness. a Predicted subglacial lake locations, using Shreve hydraulic potential equation and varying flotation fractions (f) overlain on the BedMachine DEM error map²⁸. Lakes in black coincide with hydraulic minima (using f = 0.9), whilst those in red were not successfully predicted. b Estimated geothermal heat flux derived from magnetic data²⁹. c Predicted basal thermal state¹ (blue = likely frozen, white = uncertain, red = likely thawed). d Dimensionless bed roughness beneath the GrIS³³, measured using the fast Fourier transform approach which converts bed topography (derived from radar echo sounding) into the frequency domain. Known subglacial lakes in existing literature are shown by black circles (RES-detected) and squares (detected through elevation changes). Deep ice core locations are depicted by black triangles. Lakes identified in this study are shown by circles, and the size of the circle is proportional to the minimum length of the lake reflector