Recent Fracture-Flow Variability on Thwaites Ice Shelf and Linkages to
Atmosphere-Ocean Drivers
Abstract
The rapidly-changing Thwaites Ice Shelf is crucial for understanding
ice-shelf instability and its implications for sea-level rise from
Antarctica. Fractures play a significant role in this region but are
poorly characterized, especially regarding their vertical depth. To
address this gap, we developed a robust workflow that adapts to surface
topography complexities to characterize time-varying fracture vertical
properties over Thwaites using ICESat-2 altimetry measurements. We
derived seasonal flow velocities from Sentinel-1 data and analyzed
climate reanalysis data to examine flow-fracture interactions in the
context of oceanic and atmospheric changes. The results revealed
distinct fracturing and flow patterns between the eastern and western
sectors of the ice shelf. Significant fracturing was observed along the
shear margin and near the grounding line in the eastern sector,
correlating with flow speed increases exceeding 90% at shear zones. In
contrast, the western glacier tongue exhibited a less progressive
fracturing pattern, with an active fracture zone downstream of the
historical grounding line and overall flow deceleration. This is likely
due to the stabilizing effects of grounding-zone geometry, a subglacial
sill, and increased coupling to the slower-moving eastern sector.
Atmospheric and oceanic reanalysis data suggest that
atmosphere-sea-ice-ocean interactions could destabilize an ice shelf
through shallow oceanic warming. Warm winters, reduced sea ice, and
favorable winds and ocean currents can cause shoaling of warm
Circumpolar Deep Water, facilitating access of warm waters to thin,
structurally vulnerable areas such as shear margins and basal channels.
This intensifies fracturing and triggers damage-flow-acceleration
feedback that could lead to eventual ice-shelf destabilization.