Examining the relationships between basal channels and ice shelf
structural evolution with repeat, high-resolution elevation models and
altimetry
Abstract
Ice shelves control the stability of ice sheets and regulate ice sheet
contribution to sea level rise by buttressing ice �ow. Most of
Greenland’s ice shelves have already been lost, and many ice shelves
around Antarctica are thinning and retreating. Ice shelves are
increasingly vulnerable to thinning and destabilization due to surface
and basal melting, and these processes may be exacerbated by the
presence of basal channels, which are deep grooves that entrain
meltwater at the base of ice shelves. Basal channels have been observed
alongside spatial and temporal changes in grounding line geometry,
strain rates and stress transfer, and the incidence and advection of
other surface and basal features. The relationships between these
processes, and their implications for ice shelf stability, remain
largely unknown due to the lack of observations of su�ciently high
spatial and temporal resolution. Our methodology employs high temporal
and spatial resolution digital elevation models (DEMs) from REMA and
ArcticDEM, laser altimetry from ICESat-2, radar sounding and laser
altimetry from Operation IceBridge, and velocity data derived from
interferometry, enabling us to constrain the morphology and evolution of
channels and other ice shelf features at the fringes of both ice sheets.
We intend to investigate how the relationships between channels,
grounding line processes, and rifts and crevasses impact the persistence
of ice shelf area necessary to maintain a “safety band”, or su�cient
buttressing force, against grounded ice. Where time-evolving grounding
line position data are sparse, we use the DEMs to track the boundary of
hydrostatic equilibrium, which we use as a proxy for changes in
grounding line position in order to investigate changes in ice shelf
geometry. We have completed analysis of three ice shelves and plan to
observe at least twelve more in order to develop an inventory of at-
risk ice shelves. Based on our preliminary results, we hypothesize that
rapidly evolving basal channels are associated with high rates of change
in the grounding zone. This work is integral to assessing past and
future ice shelf stability, and it will help the glacier dynamics
community more accurately account for small-scale ice shelf processes in
computational models which predict ice sheet contribution to sea level
rise.