Australia: The Land Where Time Began

A biography of the Australian continent 

West Greenland – Undercutting of Marine-Terminating Glaciers

Ice discharge into the ocean from Greenland is controlled by marine-terminating glaciers, though little is known of the frontal regions of these glaciers. In this paper Rignot et al. present the results of their study using side-looking multibeam echo sounding observations to show that the frontal ice cliffs are grounded deeper below sea level than has previously been previously measured and their faces are often undercut by the ocean and rough. Contact with subsurface, warm, salty Atlantic waters (AW), which melts ice at rates of metres per day, is enabled by deep grounding of glaciers. Cavities undercutting the base of the calving faces were detected at the sites of subglacial water (SGW) discharge that was predicted by a hydrological model. Rignot et al. say the observed undercutting pattern is consistent with numerical simulations of ice melt in which the transport of warm AW water to the faces of the ice by buoyant plumes of SWG. Rignot et al. say it is likely glacier undercutting enhances iceberg calving, which impacts on the stability of the front, and, in turn, the mass balance of the glacier.

Sources & Further reading

1. Rignot, E., I. Fenty, Y. Xu, C. Cai and C. Kemp (2015). "Undercutting of marine-terminating glaciers in West Greenland." Geophysical Research Letters 42(14): 2015GL064236.