Background
The authors write that "heterogeneous geothermal flux and sub-glacial volcanism have the potential to modulate ice sheet behavior and stability by providing a large, variable supply of meltwater to the subglacial water system, lubricating and accelerating the overlying ice," citing in this regard the work of Vogel and Tulaczyk (2006) and Schoof (2010). However, they state that "the magnitude and spatial pattern of geothermal flux are extremely difficult to measure," since "catchment-scale constraints derived from seismic tomography (Shapiro and Ritzwoller, 2004) and satellite magnetometry (Maule et al., 2005) produce contradicting spatial patterns and cannot resolve geothermal features relevant to local ice sheet forcing."

What was done
In an attempt to overcome these difficulties, Schroeder et al. used "radar echo strengths to constrain a sub-glacial water-routing model to estimate the pattern of basal melting and geothermal flux for the Thwaites Glacier catchment within the West Antarctic Ice Sheet."

What was learned
The four researchers report finding "high melt values adjacent to known volcanoes and structures that are morphologically suggestive of volcanic origin," citing Behrendt et al. (1998) and Behrendt (2013).

What it means
In the concluding sentence of their paper, Schroeder et al. say their results suggest that "the sub-glacial water system of Thwaites Glacier may be responding to heterogeneous and temporally variable basal melting driven by the evolution of rift-associated volcanism," adding that this finding supports "the hypothesis that both heterogeneous geothermal flux (Blankenship et al., 1993) and local magmatic processes (Lough et al., 2013) could be critical factors in determining the future behavior of the West Antarctic Ice Sheet." And last but by no means least, they say nary a word about climate-alarmist claims that atmospheric CO2 enrichment is the cause of West Antarctic Ice Sheet melting, which indeed it likely is not, as Antarctic sea ice continues to break records for greatest measured extent surrounding Antarctica, all the way up to the present day.

References
Behrendt, J.C. 2013. The aeromagnetic method as a tool to identify Cenozoic magmatism in the West Antarctic Rift System beneath the West Antarctic Ice Sheet - A review; Thiel sub-glacial volcano as possible source of the ash layer in the WAISCORE. Tectonophysics 585: 124-136.

Behrendt, J.C., Finn, C.A., Blankenship, D.D. and Bell, R.E. 1998. Aeromagnetic evidence for a volcanic caldera (?) complex beneath the divide of the West Antarctic Ice Sheet. Geophysical Research Letters 25: 4385-4388.

Blankenship, D.D., Bell, R.E., Hodge, S.M., Brozena, G.M., Behrendt, J.C. and Finn, C.A. 1993. Active volcanism beneath the West Antarctic ice sheet and implications for ice-sheet stability. Nature 361: 526-529.

Lough, A.C., Wiens, D.A., Barcheck, C.G., Anandakrishnan, S., Aster, R.C., Blankenship, D.D., Huerta, A.D., Nyblade, A., Young, D.A. and Wilson, T.J. 2013. Seismic detection of an active sub-glacial magmatic complex in Marie Byrd Land, Antarctica. Nature Geoscience 6: 1031-1035.

Maule, C.F., Purucker, M.E., Olsen, N. and Mosegaard, K. 2005. Heat flux anomalies in Antarctica revealed by satellite magnetic data. Science 309: 464-467.

Schoof, C. 2010. Ice-sheet acceleration driven by melt supply variability. Nature 468: 803-806.

Shapiro, N.M. and Ritzwoller, M.H. 2004. Inferring surface heat flux distributions guided by a global seismic model: particular application to Antarctica. Earth and Planetary Science Letters 223: 213-224.

Vogel, S.W. and Tulaczyk, S. 2006. Ice-dynamical constraints on the existence and impact of sub-glacial volcanism on West Antarctic ice sheet stability. Geophysical Research Letters 33: 10.1029/2006GL027345.