How much do we really know about glacier surging?

Abstract

Some of the ideas about glacier surging are considered, mainly but not entirely in the light of observations of temperate glaciers in Alaska, U.S.A., made within the last 15 years. Climate has an influence on surge recurrence interval. Climate and weather also affect surge initiation, termination and magnitude. Regional studies lead to the speculation that subglacial “till” plays a key role in surging, and it has been found under all surge-type glaciers studied so far, including Black Rapids and Variegated Glaciers, Alaska. In most of the glaciers studied, till deformation processes dominate the motion in quiescence. The linked-cavity model of surge triggering and rapid motion is not consistent with these observations, but the limited coverage of the observations does not rule it out under parts of the glaciers studied. The till observations in Alaska raise old questions about the interaction between till and the hydraulic systems of temperate glaciers. The role of stored water, which observations show to be active even in winter on Black Rapids Glacier, is noted.

Surge dynamics in the Nathorstbreen glacier system, Svalbard

“…Towards the end of stage 2 or early in stage 3, large amounts of englacial water are released, as described by Lingle and Fatland (2003). At this stage, in addition to sliding, fast flow could also arise from deformation of saturated subglacial sediments, which can accommodate an inefficient drainage system (Clarke et al, 1984;Murray et al, 2000;Harrison and Post, 2003).…”

Surge dynamics on Bering Glacier, Alaska, in 2008–2011

“…Retreat rates between 1967 and 1993 were 0.04-1.0 km yr −1 (Molnia and Post, 1995). Both the 1965Both the -1967Both the and 1993Both the -1995 surge events can be characterized as multi-staged events, beginning with a high velocity event, followed by a period of near stagnant ice, followed by another high velocity event (Harrison and Post, 2003;Molnia, 2008;Roush et al, 2003;Fatland and Lingle, 2002).…”

“…The quiescent phase lasts decades, over which the glacier develops a steeper geometry that triggers another surge event. The time required for the glacier geometry to steepen during quiescence dictates the duration of the quiescent phase and the surge cycle overall (Meier and Post, 1969;Raymond, 1987;Harrison and Post, 2003). Though there have been many studies focused on glacier surge dynamics, most of what is known about surging comes from observations on a few small glaciers over only 1-2 surge cycles (Meier and Post, 1969;Raymond, 1987;Raymond and Harrison, 1988;Bindschadler, 1982;Heinrichs et al, 1996).…”

“…Such an evolution has been closely observed on Variegated Glacier during quiescent phase (Raymond and Harrison, 1988). However, during quiescence, some surge-type glaciers have small acceleration events that redistribute thickening and thinning along the glacier profile (Meier and Post, 1969;Raymond, 1987;Harrison and Post, 2003;Raymond and Harrison, 1988;Heinrichs et al, 1996). Ultimately, the quiescent phase develops a region of thickening called the reservoir zone, which forms upstream of a thinned receiving zone.…”

The 1982/83 surge and antecedent quiescent phase of Variegated Glacier: revising the original dataset for application in flow line models

“…Harrison and others (2008) corroborated this connection. Harrison and Post (2003) found evidence for subglacial till under Variegated Glacier and speculated that till is a prerequisite for surge behaviour. The observations covered only a fraction of the glacier, hence it might be possible to reconcile these observations with the linked-cavity model of surge motion proposed by Kamb and others (1985).…”