Glaciers and ice sheets that terminate in bodies of water are expected
to undergo thermal expansion as ice comes into contact with much warmer
liquid water. Here, I investigate the roll that this thermal expansion
plays in the fracturing processes that give rise to glacier calving. I
find that thermal expansion may cause either top-out or bottom-out
rotation of a partially submerged ice cliff. I analyze temperature
borehole data from Greenland and Antarctica and find that ice cliff
thermal flexure exceeds the flexure due to buoyancy forces. This flexure
may plausibly account for the some of the net torque that gives rise to
rotational calving events in Greenland. Thermal expansion in ice
shelves, in contrast, may either stabilize or destabilize rift
propagation depending on the ice shelf thermal environment. This study
highlights the previously unexplored role of thermal fracture in the
stability of glaciers and ice sheets.