1) The eastern part of the Shackleton Ice Shelf is small and completely separate from the rest. In addition, some articles about the Shackleton Ice Shelf contain maps that show only the western (main) part.
I am therefore looking for confirmation that the eastern part is officially part of the Shackleton Ice Shelf:
> An extensive ice shelf fronting the coast of Antarctica for about 240 mi (95E to l05E); projecting seaward about 90 mi in the W portion and 40 mi in the east. The existence of this ice shelf was first made known by the USEE under Wilkes who mapped a portion of it from the Vincennes in February 1840. It was explored by the AAE under Mawson (1911-14) who named it for Sir Ernest Shackleton. The extent of the ice shelf was mapped in greater detail in 1955; using aerial photography obtained by USN Operation HighJump; 1946-47. Further mapping by the Soviet Expedition of 1956 showed the portion eastward of Scott Glacier to be a part of this ice shelf.
(Citation SCAR-Composite Gazetteer of Antarctica-Place names)
> Shackleton Ice Shelf is an extensive ice shelf fronting the coast of East Antarctica from 95° E to 105° E. It extends for an along-shore distance of about 384 km (239 mi), projecting seaward about 145 km (90 mi) in the western portion and 64 km (40 mi) in the east. It occupies an area of 33,820 square km (13,058 sq mi).
(Citation WikipediA)
> Shackleton Ice Shelf is an ice shelf in Eastern Antarctica, on the coast of Queen Mary Land (or Queen Mary Coast) and Wilkes Land, between 95° and 105° E long. The Shackleton Ice Shelf measures 440 km from west to east and 170 km from south to north. It has an area of 37,400 sq km and is 180–200 m thick. The thick Scott and Denman outlet glaciers feed into the middle parts of the shelf. Individual ice domes rise 250–300 m above the ice surface.
(Citation from The Great Soviet Encyclopedia (1979)
2) I searched the recent scientific literature to see if anything had been published about the Eastern Shackleton Ice Shelf and found only this paragraph (in which, by the way, it does not mention the Eastern Shackleton Ice Shelf, but the Glenzer Glacier).
"A strong retreat within the second decade occurred also at Glenzer Glacier next to Wilkes Land. The retreat is not yet mentioned in the literature, but satellite imagery reveals that
an important pinning point was lost in 2004, and a rift started to propagate and led to a breakup event in April 2020. We suggest that the initial destabilization and loss of the pinning
point were caused by an increase in zonal winds (+0.32 m/s) as well as enhanced surface melt (up to +0.4 mm w.e. per day) during the first decade. Increased zonal winds persisted
during the second decade (+1.23 m/s), indicating further ocean forcing. Nevertheless, the more recent calving event in April 2020 occurred due to a rift that developed over several years. Whether environmental drivers played a role or whether the rift developed due to ice flow acceleration initiated by the previous lost pinning point requires further investigation."
(Citation "Environmental drivers of circum-Antarctic glacier and ice shelf front retreat over the last two decades" 2021)
3) Images and animations of this post:
> Image S1 from yesterday: It's confirmed, there is nothing left, the Conger Tongue is completely detached, it's broken into three pieces and it's rapidly moving away (top left)
> Follow-up of calving events between 2018 and today with animation based on the following S1 images:
03/03/2018, (followed by a calving in spring 2018, after 03/03/2018)
05/03/2019, (followed by a calving in spring 2019, after 05/03/2019)
04/04/2020, 11/04/2020, 16/04/2020, 28/04/2020 (calving in spring 2020),
22/02/2021, 28/02/2021, 30/03/2021 (calving in spring 2021),
09/12/2021, 12/12/2021 (calving in winter 2021),
23/02/2022, 05/03/2022, 07/03/2022 and 17/03/2022 (final calving)
> Image from WorlView-MEaSUREs InSAR-Based Antarctica Ice Velocity Map, Version 1(2011):
Kiselëva Angarskij Glacier 150 m/yr
Glenzer Glacier 135 m/yr
Conger Glacier 265 m/yr
Angarskij Kiselëva Glacier 265 m/yr
These data are not the most recent, but they were immediately available (I will give more recent data later)
> Image from SCAR-ADD Map Viewer-Bed elevation (BedMachine)
These data are not the most recent, but they were immediately available (I will give more recent data later)
> Animation based on:
A recent S2 image (22/02/2022) and the S2 mask image on which I drew an approximate grounding line to allow a calculation of the surface of this ice shelf
4) Provisional findings:
This ice shelf was fed by four glaciers: Kiselëva Angarskij , Glenzer, Conger and Angarskij Kiselëva, with the Glenzer Glacier Tongue providing support on the pinning point corresponding to Bowman Island, the Conger Glacier Tongue providing strong support on the western side (and the major ice contribution to the ice shelf) and the other two providing external support to the bases of the two central Tongues.
It is noticeable that the Glenzer Tongue has a lower velocity than the two Tongues next to it, which must have caused some tension.
To the west no more pinning point (Unnamed Island), no more Kiselëva Angarskij Glacier Tongue (completely disrupted also in its eastern part), the fate of the Glenzer Glacier Tongue was signed and it was only a matter of time.
What I find a bit surprising is the very rapid and complete break-up of the Conger Glacier Tongue.
5) Final remark:
I have the impression that this calving has gone unnoticed outside this forum
As there is a limit of 4 images, the fifth one will be posted in the suite
Click twice to animate and fully expand the images
Correction : In the map with the speeds, as well as in the text, there was an inversion between the two names : Kiselëva and Angarskij.
Now it is fixed
