A Tale of Two Ice Shelves: Contrasting Behavior During the Regional
Destabilization of the Dotson-Crosson Ice Shelf System, West Antarctica
- Christian T. Wild,
- Tiago Segabinazzi Dotto,
- Karen E. Alley,
- Gabriela Collao-Barrios,
- Atsuhiro Muto,
- Rob A. Hall,
- Martin Truffer,
- Ted A. Scambos,
- Karen J. Heywood,
- Erin C. Pettit
Tiago Segabinazzi Dotto
University of East Anglia, University of East Anglia, University of East Anglia
Author ProfileKaren E. Alley
University of Manitoba, University of Manitoba, University of Manitoba
Author ProfileGabriela Collao-Barrios
US National Snow and Ice Data Center, US National Snow and Ice Data Center, US National Snow and Ice Data Center
Author ProfileAtsuhiro Muto
Temple University, Temple University, Temple University
Author ProfileRob A. Hall
University of East Anglia, University of East Anglia, University of East Anglia
Author ProfileMartin Truffer
University of Alaska Fairbanks, University of Alaska Fairbanks, University of Alaska Fairbanks
Author ProfileTed A. Scambos
US National Snow and Ice Data Center, US National Snow and Ice Data Center, US National Snow and Ice Data Center
Author ProfileKaren J. Heywood
University of East Anglia, University of East Anglia, University of East Anglia
Author ProfileErin C. Pettit
Oregon State University, Oregon State University, Oregon State University
Author ProfileAbstract
The Dotson Ice Shelf has resisted acceleration and ice-front retreat
despite high basal-melt rates and rapid disaggregation of the
neighboring Crosson Ice Shelf. Because of this lack of acceleration,
previous studies have assumed that Dotson is stable. Here we show clear
evidence of Dotson's destabilization as it decelerates, contrary to the
common assumption that ice-flow deceleration is synonymous with
stability. Ungrounding of a series of pinning points initiated
acceleration in the Upper Dotson in the early 2000s, which subsequently
slowed ice flow in the Lower Dotson. Discharge from the tributary Kohler
Glacier into Crosson increased, but non-proportionally. Using ICESat and
ICESat-2 altimetry data we show that ungrounding of the remaining
pinning points is linked to a tripling in basal melt rates between
2006-2016 and 2016-2020. Basal melt rates on Crosson doubled over the
same period. The higher basal melt at Lower Dotson is consistent with
the cyclonic ocean circulation in the Dotson cavity, which tends to lift
isopycnals and allow warmer deep water to interact with the ice. Given
current surface-lowering rates, we estimate that several remaining
pinning points in the Upper Dotson will unground within one to three
decades. The grounding line of Kohler Glacier will retreat past a
bathymetric saddle by the late 2030s and merge into the Smith West
Glacier catchment, raising concern that reconfiguration of regional
ice-flow dynamics and new pathways for the intrusion of warm modified
Circumpolar Deep Water could further accelerate grounding-line retreat
in the Dotson-Crosson Ice Shelf System.