CAGW proponents have alleged that West Antarctic glaciers such as such as the Thwaites Glacier and the neighboring Pine Island Glacier are rapidly melting due to man-made greenhouse gases and/or ocean heating, despite observations showing the air temperature in the Antarctic hasn’t risen since 1979, Antarctic sea surface temperatures have fallen since 2006, and ARGO ocean heat content of the Southern Ocean shows no increase at any level of the top 2000 meters since the system was put in place in 2004. The authors find the neighboring Pine Island Glacier also overlies the same volcanic rift system and thus may also be melting from geothermal heat below.
The West Antarctic Volcanic Rift System is illustrated by JoNova below, and just so happens to correspond to the areas of notable glacier melt and alleged warming. In contrast, East Antarctica, which holds > 80% of Antarctic ice mass and does not have any known underlying volcanoes, is significantly increasing in ice mass.
The paper joins several others finding geothermal heat largely if not entirely responsible for glacier melt in multiple regions in both Antarctica and Greenland, i.e. not anthropogenic.