Abstract

The combination of thinning ice cover, increasing wave amplitude owing to increasing oceanic fetch, and damage induced through diurnal thermal cycling threatens the structural integrity of the ice cover on the Arctic Ocean. Of interest, therefore, is the strength of thermally damaged ice. With that in mind, new lab experiments were performed in which thermal cracks were introduced into beams of sea ice, lab-grown saline ice and freshwater ice. Subsequently, the ice was bent to failure. The cracks initially weakened the materials, in accord with fracture mechanics. However, within a short period of time—tens to hundreds of seconds—the strength completely recovered to the level of non-cracked ice. The cracks had healed. Healing is attributed to sintering as opposing faces come into contact upon warming, assisted possibly by the presence of a quasi-liquid-layer of the kind that accounts for Faraday’s observation (1860) of immediate bonding when two pieces of ice were placed in contact. Rapid crack healing may lessen the threat to the integrity of the ice cover.