Support the Arctic Sea Ice Forum and Blog

Author Topic: Getz Ice Shelf  (Read 4998 times)

Stephan

  • Nilas ice
  • Posts: 2085
    • View Profile
  • Liked: 649
  • Likes Given: 359
Getz Ice Shelf
« on: February 14, 2020, 07:02:49 PM »
Calving at the easternmost part of the Getz Ice Shelf.
It happened some weeks ago (most likely on Jan 30). A slim part (1 km deep, 15 km long) has separated from the ice shelf and floats now in Amundsen Sea.
A detailed analysis of this region between Jan 10, 2020 and Feb 13, 2020 showed in addition several mini- and microcalvings (all circled in yellow).

See attached picture.


[PS: Neven, we should close the Getz-B47 thread]
« Last Edit: March 25, 2022, 09:38:55 AM by oren »
It is too late just to be concerned about Climate Change

Sciguy

  • Nilas ice
  • Posts: 1823
    • View Profile
  • Liked: 223
  • Likes Given: 174
Re: Getz Ice Shelf Discussion
« Reply #1 on: February 14, 2020, 07:43:56 PM »
Here's a map of Antarctica.  Getz is about midway between PIG-Thwaites and Ross.  (I had to look it up).


Stephan

  • Nilas ice
  • Posts: 2085
    • View Profile
  • Liked: 649
  • Likes Given: 359
Re: Getz Ice Shelf Discussion
« Reply #2 on: February 14, 2020, 07:50:20 PM »
That is correct. If you move to the easternmost part of Getz Ice Shelf, which covers a wide coastal area, then you get to the point where the calving has occurred. In eastern direction from there, beyond Martin Peninsula, there is the Dotson Ice Shelf.
It is too late just to be concerned about Climate Change

Stephan

  • Nilas ice
  • Posts: 2085
    • View Profile
  • Liked: 649
  • Likes Given: 359
Re: Getz Ice Shelf Discussion
« Reply #3 on: February 19, 2020, 09:29:13 PM »
Mini-Calving at Getz Ice Shelf.
This time I analysed the bay west of Wright Island. Several parts of the ice shelf calved (circled in yellow). The largest part is approx. 4 x 1 km. The resulting icebergs float along the coast in Amundsen Sea. Calving happened end January of 2020.
Nothing to worry too much about - probably the very normal calving in the austral summer...
It is too late just to be concerned about Climate Change

vox_mundi

  • First-year ice
  • Posts: 7178
    • View Profile
  • Liked: 3194
  • Likes Given: 589
Re: Getz Ice Shelf Discussion
« Reply #4 on: February 23, 2021, 09:13:45 PM »
Getz Glaciers On the Run
https://phys.org/news/2021-02-getz-glaciers.html



Using a 25-year record of satellite observations over the Getz region in West Antarctica, scientists have discovered that the pace at which glaciers flow towards the ocean is accelerating. This new research, which includes data from the Copernicus Sentinel-1 mission and ESA's CryoSat mission, will help determine if these glaciers could collapse in the next few decades and how this would affect future global sea-level rise.

Led by scientists at the University of Leeds in the UK, the new research shows that between 1994 and 2018, all 14 glaciers in Getz accelerated, on average, by almost 25%, with three glaciers accelerating by over 44%.

The results, published today in Nature Communications, also reported that the glaciers lost a total of 315 gigatonnes of ice, adding 0.9 mm to global mean sea level – equivalent to 126 million Olympic swimming pools of water.



... "Using a combination of observations and modeling, we show highly localized patterns of acceleration. For instance, we observe the greatest change in the central region of Getz, with one glacier flowing 391 meters a year faster in 2018 than in 1994. This is a substantial change as it is now flowing at a rate of 669 meters a year, a 59% increase in just two and a half decades," continued Heather.

The research, funded by the Natural Environment Research Council and ESA's Science for Society program, reports how the widely reported thinning and acceleration observed in the neighboring Amundsen Sea glaciers, now extends over 1000 km along the West Antarctic coastline into Getz.



Heather L. Selley et al. Widespread increase in dynamic imbalance in the Getz region of Antarctica from 1994 to 2018, Nature Communications (2021).
https://www.nature.com/articles/s41467-021-21321-1
“There are three classes of people: those who see. Those who see when they are shown. Those who do not see.” ― anonymous

Insensible before the wave so soon released by callous fate. Affected most, they understand the least, and understanding, when it comes, invariably arrives too late

oren

  • Moderator
  • First-year ice
  • Posts: 8023
    • View Profile
  • Liked: 3129
  • Likes Given: 3207
Re: Getz Ice Shelf Discussion
« Reply #5 on: February 23, 2021, 09:51:39 PM »
The math is weird. Speed of 669 now, higher by 391 over the year 1994. So 1994 was 669-391=278.
669 is 140% higher than 278.

391 out of 669 is ~59%, but the use of this figure in the sentence was wrong. Or the numbers were not quoted properly.

In any case, a disturbing report.

paolo

  • Grease ice
  • Posts: 888
    • View Profile
  • Liked: 408
  • Likes Given: 16
Re: Getz Ice Shelf Discussion
« Reply #6 on: February 23, 2021, 10:48:09 PM »
Oren, the percentage increase is calculated using as a base the speed in 2018 and not the speed in 1994. The value 58.5 is therefore correct, but taking 2018 as a base is, at the very least, very strange and confusing ....

EDIT: In the article, in the table where there is 58.5% the column heading is "Observed percentage speed change over25 years (%)".


Edit2: apart from this strange calculation, the article seems very interesting
« Last Edit: February 23, 2021, 11:06:25 PM by paolo »

oren

  • Moderator
  • First-year ice
  • Posts: 8023
    • View Profile
  • Liked: 3129
  • Likes Given: 3207
Re: Getz Ice Shelf Discussion
« Reply #7 on: February 24, 2021, 02:33:43 AM »
Indeed, a very interesting article.

However, their definition of "greater than" percentages is simply wrong.

Quote
Satellite data have shown that in Antarctica the dynamic ice loss (6.3 ± 1.9 mm sea level equivalent (sle)) is 86% greater than the modest reduction in surface mass (0.9 ± 1.1 mm sle) since the 1990s

Apologies for nitpicking.

Stephan

  • Nilas ice
  • Posts: 2085
    • View Profile
  • Liked: 649
  • Likes Given: 359
Re: Getz Ice Shelf Discussion
« Reply #8 on: August 07, 2021, 04:36:21 PM »
Minor calving at Getz ice shelf somewhen this Austral winter.

After checking B-22 I looked a little bit further west to find out whether something has happened. And, indeed I detected a minor calving event at the easternmost outlet of Getz ice shelf. An area of around 20*1 km of ice was lost to the sea (circled in orange).

See attached picture (left above May 2021, right above August 2021, the picture at the bottom shows where this outlet of Getz ice shelf is located (green box)).
It is too late just to be concerned about Climate Change

Stephan

  • Nilas ice
  • Posts: 2085
    • View Profile
  • Liked: 649
  • Likes Given: 359
Re: Getz Ice Shelf Discussion
« Reply #9 on: January 23, 2022, 09:43:34 PM »
Micro calving at the Western part of Getz Ice Shelf. A portion of ice of ca. 7 km * 0.7 km area got lost last week (circled in green). Where exactly this happened, see first picture. The second picture shows the position in a larger context (the frame of the first picture is in the green square).
It is too late just to be concerned about Climate Change

Stephan

  • Nilas ice
  • Posts: 2085
    • View Profile
  • Liked: 649
  • Likes Given: 359
Re: Getz Ice Shelf Discussion
« Reply #10 on: January 23, 2022, 10:11:03 PM »
Another micro calving at the Eastern part of Getz Ice Shelf.
A portion of ca. 6 * 0.5 km² of ice was lost last week (green circle). This happened at the second outlet of Getz Ice Shelf, if you start counting from its eastern end. For the position of Wright Island see reply #8 of this thread.
See attached picture.
« Last Edit: January 23, 2022, 10:48:31 PM by Stephan »
It is too late just to be concerned about Climate Change

Stephan

  • Nilas ice
  • Posts: 2085
    • View Profile
  • Liked: 649
  • Likes Given: 359
Re: Getz Ice Shelf Discussion
« Reply #11 on: January 24, 2022, 07:40:47 PM »
Another micro-calving at Getz Ice Shelf. This time the westernmost part is affected. Around Jan 16 a piece of ca. 6 * 0.5 km² broke off (first picture, circled in green). West of it two rifts became wider and deeper (or, maybe, fast ice simply disappeared, green arrows). The zoomed part of the first picture is located in the red square of the second picture. It was cloudy there yesterday so I didn't detect it when I scanned Getz Ice Shelf for further calvings.

See attached pictures.
It is too late just to be concerned about Climate Change

oren

  • Moderator
  • First-year ice
  • Posts: 8023
    • View Profile
  • Liked: 3129
  • Likes Given: 3207
Re: Getz Ice Shelf Discussion
« Reply #12 on: January 25, 2022, 01:10:40 AM »
A quick web search gives Getz speed as ~500m/y. So it seems the calved locations roll the front back by ~1 year.

Stephan

  • Nilas ice
  • Posts: 2085
    • View Profile
  • Liked: 649
  • Likes Given: 359
Re: Getz Ice Shelf Discussion
« Reply #13 on: January 31, 2022, 09:10:21 PM »
A new calving at Getz Ice Shelf.
A portion of 7 * 0.5 km has calved yesterday, close to Duncan Island in the Eastern part of Getz Ice Shelf (circled in red).

See attached picture, and in the second picture the position of the first picture (blue box) in the larger context.
It is too late just to be concerned about Climate Change

Stephan

  • Nilas ice
  • Posts: 2085
    • View Profile
  • Liked: 649
  • Likes Given: 359
Re: Getz Ice Shelf Discussion
« Reply #14 on: February 02, 2022, 08:42:50 PM »
New micro calving at Getz Ice Shelf between Duncan and Wright Island. A portion of around 4.5*0.5 km has calved. This is a follow-up of the calving I reported about on Jan 31.

See attached picture, for the position see the blue box in the second picture from my posting on Jan 31.
It is too late just to be concerned about Climate Change

Stephan

  • Nilas ice
  • Posts: 2085
    • View Profile
  • Liked: 649
  • Likes Given: 359
Re: Getz Ice Shelf Discussion
« Reply #15 on: February 02, 2022, 10:16:01 PM »
Analysis of the decrease and growth of Getz Ice Shelf in the last 11 years from EOSDIS

If you look at EOSDIS you can see the front of the ice shelf as it was end of 2010 as a thin white line. I compared the area that was lost or gained since then until this week by measuring the area between that thin white line and the actual cliff position, sorted by outlet flow numbers (No) from the attached figure from East to West. The entries are divided by the different islands.

Martin Island
Nos 1-2    - 164 km²
Wright Island
Nos 3-4    -   40 km²
Duncan Island
(no No)    -   27 km²
Carney Island
No 5        +    9 km²
Siple Island
Nos 6-7    +  44 km²
Dean Island
Nos 8,9,10 - 418 km²
Grant Island
Nos 11-12  -  85 km²

In summary around 680 km² of ice shelf was lost since end of 2010, the greatest loss happened between Dean and Grant Island, which is also the largest outlet and thus less supported by land.
It is too late just to be concerned about Climate Change

oren

  • Moderator
  • First-year ice
  • Posts: 8023
    • View Profile
  • Liked: 3129
  • Likes Given: 3207
Re: Getz Ice Shelf Discussion
« Reply #16 on: February 03, 2022, 01:05:36 AM »
Thanks for the long term analysis.
According to this map the area of Getz Ice Shelf is 32,810km2, which means more than 2% was lost since 2010.


Stephan

  • Nilas ice
  • Posts: 2085
    • View Profile
  • Liked: 649
  • Likes Given: 359
Re: Getz Ice Shelf Discussion
« Reply #17 on: February 03, 2022, 12:44:11 PM »
Analysis of the decrease and growth of Getz Ice Shelf in the last 21 years from EOSDIS

If you look at EOSDIS you can see the front of the ice shelf as it was end of 2010 as a thin white line. I compared the area that was lost or gained since then until this week by measuring the area between that thin white line and the actual cliff position, sorted by outlet flow numbers (No) from the attached figure from East to West (black numbers). In addition I measured the changes between Feb 2001 and end 2010 (blue numbers). The entries are divided by the different islands.

Martin Island
Nos 1-2    - 142 km²   - 164 km²
Wright Island
Nos 3-4    -   48 km²    -   40 km²
Duncan Island
(no No)    -     3 km²    -   27 km²
Carney Island
No 5        -   25 km²    +    9 km²
Siple Island
Nos 6-7    - 187 km²    +  44 km²
Dean Island
Nos 8,9,10 + 359 km²   - 418 km²
Grant Island
Nos 11-12  + 130 km²   -  85 km²

The difference between 2001 and 2010/11 was + 84 km².
The difference between 2010/11 and 2022 was - 680 km².

Unfortunately no EOSDIS pictures earlier than 2001 are available.
It is too late just to be concerned about Climate Change

Stephan

  • Nilas ice
  • Posts: 2085
    • View Profile
  • Liked: 649
  • Likes Given: 359
Re: Getz Ice Shelf Discussion
« Reply #18 on: February 13, 2022, 07:07:46 PM »
New micro calvings at Getz Ice Shelf.

Again the eastern part between Duncan and Wright Island is affected. A portion of 4 * 0.7 km² of ice calved from this ice shelf (blue circle in the first picture).
The second picture shows the position in the larger context. The blue box is, once again, applicable.

The third EOSDIS picture shows a calving in action at the western end of Getz Ice Shelf (green circle), about 5 * 0.6 km² ice was lost.
For its position see green box of the second picture.
« Last Edit: February 13, 2022, 07:19:18 PM by Stephan »
It is too late just to be concerned about Climate Change

Stephan

  • Nilas ice
  • Posts: 2085
    • View Profile
  • Liked: 649
  • Likes Given: 359
Re: Getz Ice Shelf Discussion
« Reply #19 on: March 08, 2022, 09:28:57 PM »
Another micro calving at Getz Ice Shelf.
Once again the westernmost part, west of Grant Island, is affected.
Due to the cloudy conditions a valuable information about the size of this calving can not be given. One of the tongues that were close to the calving of Jan 24 has now disappeared.

See attached first picture (size approx. 107*77 km, north is roughly left below), the event took place in the red circled area.

For the larger context please refer to the red box of the second picture.
It is too late just to be concerned about Climate Change

Stephan

  • Nilas ice
  • Posts: 2085
    • View Profile
  • Liked: 649
  • Likes Given: 359
Re: Getz Ice Shelf Discussion
« Reply #20 on: March 10, 2022, 09:32:27 PM »
Four more micro calvings at the westernmost part of Getz Ice Shelf.
Finally a clear day allowed a more detailed look at this Ice Shelf. I circled areas in red where some parts of the ice shelf have calved since the last clear day (Feb 24). The largest part has an area of 4.5 * 1 km.

See attached picture.

For the larger context of this part of Getz Ice Shelf see the red box in the second picture of reply #19 of this thread.
It is too late just to be concerned about Climate Change

Stephan

  • Nilas ice
  • Posts: 2085
    • View Profile
  • Liked: 649
  • Likes Given: 359
Re: Getz Ice Shelf Discussion
« Reply #21 on: March 12, 2022, 09:26:40 PM »
Another calving at Getz Ice Shelf. Very active this melting season.
Compared to the other calvings I reported of this one is larger (9.5 * 1.5 km²). It happened at the easternmost part of Getz Ice Shelf (circled in yellow) between Martin and Wright Island. See attached picture, which has a size of approx. 95*75 km.

For the position of this outlet of the Getz Ice Shelf please refer to the second picture (yellow box). North is left down.
« Last Edit: March 12, 2022, 09:35:58 PM by Stephan »
It is too late just to be concerned about Climate Change

FredBear

  • Frazil ice
  • Posts: 322
    • View Profile
  • Liked: 49
  • Likes Given: 39
Re: Getz Ice Shelf Discussion
« Reply #22 on: March 24, 2022, 06:40:44 AM »
In the previous post Martin Island appears at the top of an image. There is an indent in this island's coastline from which there now appears to be a plume of ice deflecting westwards towards an iceberg that has been grounded nearby all summer.
I don't know if this "plume" is just seasonal freeze-up or signs of fast-ice/glacier breaking up (it also appears on an earlier 30 March 2019 Worldview image)?