Thwaites Glacier Discussion

[Chris83]

  The triangle is clearly moving faster and faster
  Open water hasn't reached TEIS (yet?). A lot of small icebergs are now detached, but not on the move because of the remaining sea ice.
  The northern part of the tongue is also seeing some small changes. (not shown)
  The continent is very cold this winter (-44c again today)

[Carbon for the Carbon God]

It appears the triangle has broken loose completely, judging by the latest image.

What will carbon do? The tides and currents taketh the triangle to its last voyage?

I am assembling a seasoned team of scientists and engineers as we speak. Multiple billionaires on this team. Our Triangle Retrieval Vessel is equipped with hundreds of Nvidia GPUs to power our AI. It will assist us in the marketing of our exotic bottled water!

Thank you to everyone for providing intelligence here. We are still spinning up our own analysis capabilities. I know a few ex-NGA analysts who are keen to get in on the ground floor... or should I say the proverbial seafloor?

[baking]

And so it begins...  3-day Worldview GIF.

[Chris83]

  There is a new low quality sat photo (30.12.2024) today
  A few changes : the triangle is on the move (South) as we already knew
  Calving is about to happen (Area North of TEIS .. Red arrow)
  There is also some movement South of the tongue. The loose sea ice is finally moving (area with the longitude data (75)).
  More open water is visible in the area, but still quite far from the coastline.
 My 2-cent opinion: the sea ice plays an important role, holding the area together for the moment.

[FishOutofWater]

An open access paper was published in October explaining the dynamics of Thwaites calving.

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2024JF007737

Here's the abstract.

Abstract

The western region of the wide Thwaites Glacier terminus is characterized by a near-vertical calving front. The grounding line at this western calving front (WCF) rests on a relatively high ridge, behind which exists a reverse-sloping bed; retreat of the grounding line into this over-deepening basin could therefore expose deep calving faces that may be subject to ice-cliff failure. Here, we use the 3D Helsinki Discrete Element Model to identify the factors that control the calving dynamics in this location. We then focus on the ability of mélange to influence these dynamics given the wide embayment in which Thwaites Glacier terminates. We find that calving along the WCF is currently influenced by ice flow across the grounding line and consequent longitudinal tensile stress and rift formation. Calving is slowed in simulations that are initiated with a highly constricted mélange, with a thicker mélange suppressing calving entirely. We liken the constrained simulations to a scenario in which mélange piles behind a large grounded iceberg. In a future which may see calving become a more dominant control on the retreat of Thwaites Glacier, this type of blockage will be necessary for robust force chains to develop and transmit resistive forces to the terminus. The ability of the mélange to hinder calving at this location will be determined by the presence and rigidity of binding land-fast sea ice and iceberg keel depths. Therefore, it is necessary to represent calving, mélange and sea ice in a single framework to predict the fate of Thwaites Glacier.

Key Points

1.  Calving at Thwaites Glacier's western terminus is controlled by longitudinal tensile stresses and fracturing as basal traction is lost

2.  3D modeling demonstrates that mélange, if constrained, can inhibit calving at this location

3.   Future sea-ice conditions and iceberg morphology will determine if mélange can compact and transmit substantial resistive forces

[baking]

Sea ice off of Thwaites breaking up.  5-day Worldview GIF.

[baking]

Large 5-day low-res GIF shows major calving on the Western Calving Front (WCF) affecting the Tongue, the melange, and the sea ice.  This calving occurred between Dec 28 and Dec 30.

[Chris83]

  Happy new year
  Thanks @baking for the GIF
  Today's sat photo is low quality again
  I am impressed by the damage in the tongue area ...Small icebergs have truly melted away
  I am also curious to see what will happen when/if the open water reaches that area (not yet happened)
  2 large areas (red arrows) with damage are visible  and it seems it is triggering more calving near the coastline (to be confirmed)

[Chris83]

   I was given another tool to track the Thwaites area. (Copernicus)
   I found this quite interesting.
   It's an enhanced view of TEIS today (different angle from the polarview sat photo). 03.01.2025
   Check the "triangle" on the move
  The large crack I mentioned a few weeks ago is approx 14 kms long and quickly growing (compared with 14.12.2024)

[Chris83]

New sat photo (04.01.2025) with bad resolution again
The open waters haven't reached the coastline

The tongue area is finally experiencing massive changes. New massive cracks have appeared (red arrows), and calving has accelerated. An area seems to experience more melting (and faster)

Worth mentioning also
Antarctica data : Loss 208k on the 03.01.2025
Sea ice: 6.505.620 km2 from 6.713395 yesterday
Approx 75 k more than the average loss on this day of 133k

[Chris83]

Another view of the area

Open water is becoming visible near the moving triangle

The 2 highlighted areas with red arrows show where small icebergs are on the move, heading East.
This is also the area when sea ice seems to be melting the most, lately.

As mentioned in an earlier post, the area is only holding together because of sea ice.
47 days to maximum (approx) and lots of heat is expected this week in that area (GFS forecast)

[baking]

He is today's 5-day low-res GIF of the calving across the entire width of Thwaites Tongue.  This follows the massive calving from October 12.  https://forum.arctic-sea-ice.net/index.php/topic,1760.msg412319.html#msg412319

[Stephan]

Thank you for sharing. Is a combination video of this event and the October event possible?

[baking]

Thank you for sharing. Is a combination video of this event and the October event possible?

This GIF has 5 images in roughly equal intervals of 24 days with one at 36 days, but the 36 day interval was not a dramatic change.

[Stephan]

Thank you. In the sum an impressive movement and calving.

[Chris83]

  I am experiencing issues to post.
  I suggest checking the new Polarview photo as lots of things are happening in several areas.
  I will try again later.

[Chris83]

The new Polarview photo 05.01.2025

[baking]

During the peak of the Antarctic Summer, there is a lot of melted water in the upper surface of the snowpack so the radar images can look a little darker, and things like crevasses can look bigger and more dramatic.  In the past, those crevasses have closed up again, but there are more of them than in the past and if (when) the Thwaites Eastern Ice Shelf (TEIS) becomes ungrounded they could be a problem for the survival of TEIS.

That said, I think you missed the big action today which is the sea ice you cut off from your image.  Here is a 12-day GIF, scaled down 4x from the high-res image.

[Chris83]

    I saw that
   but unable to post (both computer and phone)

[steve s]

A one year comparison over a large swath of the Thwaites might well be illuminating. I suspect the shelf is moving noticeably and the stresses involved probably would be revealed in the nearby crevasses to the south.

(Apologies for having no means of generating an appropriate image.)

[Chris83]

Thwaites 05.01.2024

[steve s]

Thanks Chris, but the image covers too small an area and, since it is not aligned with a current image, comparison is difficult.

[baking]

A one year comparison over a large swath of the Thwaites might well be illuminating. I suspect the shelf is moving noticeably and the stresses involved probably would be revealed in the nearby crevasses to the south.

Here is a one-year comparison scaled down x6 to cover a large an area as possible.

[steve s]

Thanks Baking.

To me, the annual change clarifies the rate of change and the stresses driving that change better than images comparing shorter intervals. The EIS seems to be moving north fast enough to expect it to be gone in a few years.

[baking]

Thanks Baking.

To me, the annual change clarifies the rate of change and the stresses driving that change better than images comparing shorter intervals. The EIS seems to be moving north fast enough to expect it to be gone in a few years.

TEIS is huge.  You could argue from the GIF that it is being pushed by a tiny strip of fast-moving ice on its Western edge.  It is also still grounded at its Northwestern corner.  Things might continue in this way or not.  Something as large as the TEIS is just not going to float off to sea.  If it stops moving, those crevasses will close up again as the ice in the center near the grounding line catches up.

What this does mean is that the ice shelf is not currently holding back a lot of the ice behind those crevasses and we may see an increase in the ice velocity there.  This can cause a snowball effect as faster-moving ice will become thinner and then float more pushing the grounding line back which might eventually start something called a Marine Ice Sheet Instability (MISI) but that is down the road a few decades at least.

[steve s]

I suspect its time to consider the pinning area at the NW corner apart from the EIS. The melange between the two allow quasi-independent movement by the EIS.

In addition, there seems to be a slight counterclockwise rotation of the pinning area. One indication is the clockwise rotation of the "Triangle" berg, seemingly in response. So the ice may be thinning to a critical degree.

Decades until large changes may be optimistic.

[Chris83]

Thwaites 07.01.2025 part 1
2 posts as the Copernicus website only works when zooming in
Keep in mind the data is not displayed the same way as on Polarview

A big piece of sea ice broke off the last 4 days
Another piece broke off TEIS (XX ...check red arrow)
Sea Ice also came back along the coast line in the Southern part

[Chris83]

Part 2 07.01.2025

The triangle appears to be grounded again
More open water is visible near it
Sea ice is also coming to the coast line in that area (the arrow shows the direction of movement the last 4 days)

Great tool to monitor the area IMO

A massive area of ice North of TEIS broke off along the coast line . Nearly 55 kms long. The iceberg is 20 x 24 kms long...

[Chris83]

   Not much going on at Thwaites lately (today 11.01.2025)
 Open water is now coming near the coast line.
 Some small patches are visible in the south and southwest of TEIS.
Worth mentioning, a massive heatwave is expected in Antarctica next week (begins D+6)
The "triangle" seems grounded again.The Tongue seems stable also.

[Chris83]

A small GIF about TEIS as an image was published yesterday (12.01.2025)
First image 23.12.2024
It seems change has stalled again, and the "triangle" seems grounded.
The large crack is not expanding for the moment.
Massive heat is coming to the continent mid week, for several days, but the area will avoid most of it.

[baking]

2-day low-res GIF showing the Triangle pivoting again.

[baking]

1-day GIF from Worldview showing some crumbling on the sea ice front North of Thwaites.  This was not shown on today's 4am UTC Sentinel-1 radar image but was visible on the first optical images after dawn, so it happened in the past 10 hours.  I will update it later in the day if any further changes or clearer images come from Worldview.

[baking]

Updated image from Wordview.  That's pretty thin ice that's remaining between Thwaites and open water.

[oren]

2-day low-res GIF showing the Triangle pivoting again.

The triangle is also "uncorking" the smaller piece near the rotation axis.

[baking]

Sea Ice continues to collapse North of Thwaites.  GIF of three successive days.

[Chris83]

Thwaites new Polarview photo 16.01.2025

The triangle is on the move, and quite quickly
The sea ice near the coastline is not melting fast enough and is holding the area together (IMO)
A massive heatwave is on the way over the continent, and it seems it will last at least 2 weeks.
The glacier area should avoid the worst of it. Models are not in agreement for the 2sd week.

[baking]

12-day low-res GIF showing the loss of protective sea ice North of Thwaites.

[Chris83]

Copernicus has updated the photos today (16.01.2025)
Small 4-day GIF around TEIS
The triangle is on the move again. And open water has arrived along the coastline.
A massive heatwave is also on the way, and for many days.
35 days to sea ice minimum according to Gerontocrat.
The sea ice is holding the area together. It is obvious when zooming in.
Truly an amazing tool from Copernicus.

[baking]

Truly an amazing tool from Copernicus.

Sentinel-2 satellites repeat orbits every 10 days.  If you can find two clear images from ten days apart you can make a GIF without any angular distortions.  When it works, Sentinel-2 can be very nice, but I have pretty much given up on it because of the steep learning curve and I forget how to use it (or they change the user interface) from one season to the next.  (I also have trouble remembering what custom scripts work best or what works one day doesn't work the next.)

[Chris83]

  It seems to be a very useful tool during this period (end of summer) to monitor the various cracks and the arrival of open water.
They offer different tools to measure or download images . The zoom is also very powerful.
I find it really helpful, considering events happening in Antarctica.
I have no doubt experts can do much better than these simple images or GIF. I simply thought it would be a nice addition to the thread.
Ongoing events are very interesting.

[Chris83]

   The ongoing heatwave is triggering big changes around TEIS
The open water has arrived on the coastline, as large areas of the sea ice disintegrated.
New sat photo today (Polarview)
Cracks are also appearing elsewhere
Small GIF 11.01 and today

[baking]

I was going to post a 12-day GIF from Polarview, but this morning's first images from Worldview show that Polarview is already out of date.

Here is a one day GIF showing the fixed part of Thwaites Eastern Ice Shelf (TEIS) now exposed to open water.

Edit:  Adding a later and clearer image from today.

[Often Distant]

A duration of 2 years at 12 day intervals.

[Stephan]

Thank you for sharing this.
Finally in my opinion the calving front of the glacier doesn't change much in position.

[Often Distant]

Thwaites Eastern Ice Shelf.
A duration of roughly 10 years at intervals of roughly 3 months.

[VeliAlbertKallio]

The big smooth piece of ice shelf in the middle seems to be progressively and steadily getting more fractured on video as the years pass, suggesting that its quality is weakening over time, and would continue to do so in the future as fractures in it grow in number and widen. I wonder if its demise will help the fratured ice around and behind to start behaving differently once the smooth section continues to fracture further. Could the ice be now warmer and hence softer that 10 years ago when video began? Although far from rotten, honeycombed ice, it suggest me incremental tiny softening.

[oren]

I think both of the long term animations (thank you OD) show a sharp reduction in buttressing, which could cause the forward speed to increase, and the calved icebergs to disperse if the sea ice disperses.

[steve s]

The last three images of the second animation show something akin to a tripling in the northern rate of travel of the smooth section of the ice shelf. I specify the smooth section to distinguish it from the pinned northwest corner which is now separated from the rest of the shelf by a melange.

[Often Distant]

I believe the smooth section is above a deeper depression than the rest of the ice shelf, with depths exceeding 1,000m, compared to roughly 500m or less under the rest of the shelf. It doesn't mean the ice is thick enough to occupy the depths, but that it largely bounces up and down on the tides without hitting rock, keeping it much more solid than the rest of it. The shelf is close to 600m thick. If the shelf soon colapses, it is possible large icebergs from the smooth section will remain constrained by the bathymetry for decades to come. Triangular bracing for the shelf from the coast line is fragile. Much of the shelf can be sucked out as melange when sea ice clears. A significant proportion of Thwaites force from the broken tongue section is temporarily pushing on an angle into TEIS. A very active situation. I think the second gif is destined to look more like the first gif within a few years.

Some current info:

A recent study by a team of researchers from the International Thwaites Glacier Collaboration (ITGC) has found that the Thwaites Eastern Ice Shelf – the last floating extension of Thwaites into the ocean - is rapidly destabilising due to widening cracks, not melting from below as previously thought.

Since 2016, cracks, or "rifts," in the ice shelf have been rapidly spreading and deepening, especially during the Southern Hemisphere’s spring season (Sep-Nov). These rifts have sped up the ice shelf’s movement by about 70%, with the central part now moving nearly three metres a day, compared to just under two metres a day in 2019. This acceleration also affected the structural integrity of the ice shelf, and since 2020 has contributed to the formation of large gaps filled with icy debris. Additionally, recent loss of sea ice around the ice shelf has allowed part of its western edge to detach from its main anchoring point on the seafloor.

Sensors placed along the ice for the study, which was published in September 2024 in the Journal of Glaciology, have shown that despite warming ocean waters, melting beneath the shelf is surprisingly low. This is likely because there’s a layer of buoyant freshwater below the ice that keeps warm ocean water from directly melting the ice from underneath.

What these findings as well as further computer modelling suggests is that, while warm ocean waters are preconditioning ice loss in West Antarctica, it is the ongoing internal destabilisation that now poses the greatest threat to the Thwaites Eastern Ice Shelf. The ice shelf is in its final phase of disintegration as these cracks grow, independent of melting from below.

Lead author of the study, Dr Christian Wild from Oregon State University says:

“We anticipated that the Thwaites Eastern Ice Shelf would break up within the next decade, but never so quickly – it’s like watching the final act of a disaster unfolding.”

This discovery highlights the complexity of Antarctic ice dynamics and amplifies concerns over the future stability of Thwaites Glacier, whose complete collapse could significantly raise global sea levels.

https://thwaitesglacier.org/news/thwaites-eastern-ice-shelf-cracks-spread-not-because-melting

[baking]

The smooth area of Thwaites Eastern Ice Shelf (TEIS) is from a time around 2006 when the main trunk (high-velocity portion) of Thwaites which is at the base of Thwaites Tongue started pushing towards the East and the ice shelf just slid right past the grounded portion of the shelf for a few years.  If you look through the older posts on this thread you can probably find an animation of it, but the satellite imagery was not as good back then.

Edit:  It's called the "TEIS acceleration event" in this paper and occurred from 2002 through 2006:  https://tc.copernicus.org/articles/16/2545/2022/

Also: https://forum.arctic-sea-ice.net/index.php/topic,1760.msg328062.html#msg328062