I have referenced Milillo et al. (2019) previously; however, as it tells part of a complex/heterogeneous story of the portion of the Thwaites Glacier gateway between the east side of the base of the Thwaites Eastern Ice Shelf (TEIS) and the west side of the base of the Thwaites Ice Tongue, I use it to kick-off a series of Replies using previously posted information in order try to emphasize how this dynamic area of the Thwaites Glacier gateway could lead to the initiation of an MICI-type of failure for the Thwaites Glacier beginning around 2035 to 2045.
In this regard, the first attached image (Fig 1) shows this critical portion of the Thwaites gateway where:
1. Panel A/B shows the bed topology (blue with white contour lines) and areas of high basal ice melting (red zones) associated with the influx of warm CDW (yellow arrows).
2. Panel C shows DinSAR data and points A, B & F (near what I later call the Big Ear) and points C, D & E (to the east of what I later call the Little Ear).
3. Panel D shows the height above floatation.
4. Panel E shows change in ice surface elevation, dh, between decimal years 2013.5 and 2016.66.
5. Panel F shows ice flow velocities (with the highest velocities at the west side of the base of the Thwaites Ice Tongue).
The second image (Fig 2) zooms in on the points A, B & F (with high basal ice mass loss near the grounding line and high changes in the ice surface elevation) and points C, D & E (with high basal ice mass loss near the grounding line but with lower changes in the ice surface elevation)
The third image (Fig 3) shows the subglacial cavity in this area with Panel C focused on the Big Ear area (points A, B & F).
The fourth image from Tinto & Bell (2011) shows what I call the Big Ear and Little Ear areas prior to 2011 in relation to both the TEIS, the Thwaites Ice Tongue and the bed trough that extends from the ocean to the Byrd Subglacial Basin, where I suspect that ice-cliff failures may begin as early as 2035.
P. Milillo, E. Rignot, P. Rizzoli, B. Scheuchl, J. Mouginot, J. Bueso-Bello, and P. Prats-Iraola (2019), "Heterogeneous retreat and ice melt of Thwaites Glacier, West Antarctica", Sci Adv. 5(1): eaau3433, doi: 10.1126/sciadv.aau3433
PMCID: PMC6353628
PMID: 30729155
https://advances.sciencemag.org/content/5/1/eaau3433&
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6353628/Abstract: "The glaciers flowing into the Amundsen Sea Embayment, West Antarctica, have undergone acceleration and grounding line retreat over the past few decades that may yield an irreversible mass loss. Using a constellation of satellites, we detect the evolution of ice velocity, ice thinning, and grounding line retreat of Thwaites Glacier from 1992 to 2017. The results reveal a complex pattern of retreat and ice melt, with sectors retreating at 0.8 km/year and floating ice melting at 200 m/year, while others retreat at 0.3 km/year with ice melting 10 times slower. We interpret the results in terms of buoyancy/slope-driven seawater intrusion along preferential channels at tidal frequencies leading to more efficient melt in newly formed cavities. Such complexities in ice-ocean interaction are not currently represented in coupled ice sheet/ocean models."
Caption for the first image (Fig 1): "Thwaites Glacier, West Antarctica.
(A) Map of Antarctica with Thwaites Glacier (red box). (B) Shaded-relief bed topography (blue) with 50-m contour levels (white) (16), grounding lines color-coded from 1992 to 2017, and retreat rates for 1992–2011 (green circle) versus 2011–2017 (red circle) in kilometer per year. Thick yellow arrows indicate CDW pathways (32). White boxes indicate outline of figs. S1 and S2 (C) DInSAR data for 11 to 12 and 27 to 28 April 2016, with grounding lines in 2011, 2016, and 2017 showing vertical displacement, dz, in 17-mm increments color-coded from purple to green, yellow, red, and purple again. Points A to F are used in Fig. 2. (D) Height of the ice surface above flotation, hf, in meters. (E) Change in ice surface elevation, dh, between decimal years 2013.5 and 2016.66 color-coded from red (lowering) to blue (rising). (F) Ice surface speed in 2016–2017 color-coded from brown (low) to green, purple, and red (greater than 2.5 km/year), with contour levels of 200 m/year in dotted black."
Caption for the second image (Fig 2): "Changes in ice surface elevation, h, of Thwaites Glacier.
(A to F) from TDX data (blue dots) for the time period 2011–2017 over grounded ice (red domain, dh/dt) at locations A to F, with height above floatation, hf (red lines), and 1σ uncertainty (dashed red lines), converted into change in ice thickness, H, over floating ice (blue domain, dH/dt) in meters per year. Black triangles are TDX dates in (G) to (J). (G and H) Main trunk. (I and J) TEIS. Grounding line position is thin black for 2016–2017 and white dashed blue for 2011."
Caption for the third image (Fig 3): "Ice thickness change of Thwaites Glacier.
(A) Ice surface elevation from Airborne Topographic Mapper and ice bottom from MCoRDS radar depth sounder in 2011, 2014, and 2016, color-coded green, blue, and brown, respectively, along profiles T1-T2 and (B) T3-T4 with bed elevation (brown) from (16). Grounding line positions deduced from the MCoRDS data are marked with arrows, with the same color coding. (C) Change in TDX ice surface elevation, h, from June 2011 to 2017, with 50-m contour line in bed elevation and tick marks every 1 km."