Abstract

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.