Ice caps / All Greenland

[Espen]

I have done a fever test series over the last few weeks, mostly showing retreating Ice Caps / Firns etc., I find it just as important to watch these land based Ice Caps, as the glaciers, because in my opinion these Ice Caps behavior is more weather related (temperature) than glaciers because the later can be influenced by other factors like the sea, currents, tides etc.

The first sample I will show on this thread is from Washington Land, North West Greenland, and it is John Brown Iskappe which is a fairly low altitude Ice Cap (~865 meter).
As suspected the Ice Cap is showing signs of retreat, because when you see rocks grow, something is wrong, especially when you watch an Ice Cap from above:

[Espen]

2nd Ice Cap to report is from Lambert Land, the "island" between 79 to the north and Zachariae Isstrøm to the south.
The name Lambert Land was first reported on a Dutch map from 1718 as t'Land van Lambert a Dutch whaler who discovered the "island" in 1670.
As you can see the all the various ice caps on the "island" are retreating.
The "island" is even even growing if you watch carefully especially towards Zachariae, a sign Zachariae is thinning.
Note the melt lakes on Zachariae more or less stay put where they are even over a period of ~40 years, although several kms of glacier ice passed these points over the same period.
Highest point on the "island" is 1097 meter.

[Espen]

3rd Ice cap to report from, is from Disko Ø, the largest island in Greenland and the home of Storbræen, which is really a very large ice cap, with several glacier arms, although there is lots of evidence of massive ice loss in the period 1979 - 2014. Some of the glacier arms actually expanded?
(watch 2nd animation)
My first guess it is due to the melting this resulting in more dynamics in the ice left, but I may be wrong?
Maybe our friend Mauri Spelto can explain this behavior?

[Espen]

Another Ice Cap (unnamed), which will probably be gone in a few years, this time from Washington Land, this ice cap is just above Romer Søer (Romer lakes) and very close to Petermann Gletscher:

 

[crandles]

Great fever tests, Wipneus 

Is it possible to do pixel counts on earliest and latest images. If it is possible, can the area loss % be converted to rough volume loss % by assuming some shape like a cone and that the same thickness has been removed from all points or would the errors from such assumptions be too large?

[Espen]

This giant is out of normal order, since it can be called both a glacier or an ice cap, depending on your mood!
This time Frederikshåb Isblink from South West Greenland, as you can see from the animation below this giant is also sweating (the width of the animation is ~72 km):

[Shared Humanity]

Are these images from the same time of year? The 2014 image has far more green on the ice free land.

[Espen]

Are these images from the same time of year? The 2014 image has far more green on the ice free land.

Yes, normally within 2-3 weeks in july-august, color variation can be due to different sat/sensor.

[Shared Humanity]

Unless I am mistaken, some of this additional green is occurring where land is emerging from areas that seemed to be open sea in 1985. This is especially evident in the northwest portion of the picture. How could land appear like this? Is the sea level dropping? Is the land rising (isostatic rebound)? In a couple of cases, it looks like small bridges of land have cut off water that use to reach the sea.

One of the most eye popping changes is on the far left of the image. There is a large area of brown that has appeared in what seems to be open water. Is this silt that is floating in the water?

[Shared Humanity]

I am beginning to think these are just shadows obscuring the land in the 1985 image. Nevermind.

Although the region where silt seems to exist does not look like shadow effects.

By the way, I've said this before but I love these images that you provide that show changes in Greenland.

[Shared Humanity]

Looking at where this brown area (silt?) is appearing, a huge area stretching south of this spot has an entirely different look topographically than the areas around it. The surrounding areas are high rocky land while this large feature seems to have the characteristics of a huge river delta. Could the melt of the retreating ice shelf be revealing a low river delta?

I wish I had a good pair of boots and could hike along here.

[Shared Humanity]

Looks like they are planning oil exploration in this area and identifying areas to contain the inevitable spills.

http://www.geus.dk/departments/quaternary-marine-geol/oliespild_v_gr/PDFfiles/Chapter9/Map6252L.pdf

[Shared Humanity]

I believe I've answered my question. This appears to be a large river delta.

http://www.geus.dk/departments/quaternary-marine-geol/oliespild_v_gr/PDFfiles/Chapter9/Map6251L.pdf

[mspelto]

The glacier arm that advanced on the Disko Island, seems to have a looped moraine, this suggests a possible surge.  The image is not good quality. 

[sidd]

Velicogna(2014) doi:10.1002/2014GL061052

"Overall, in Greenland, SMB has contributed 68% of the GRACE-derived
mass loss (-180±33 Gt/yr versus a total loss of -265±59 Gt/yr) and 79%
of the observed acceleration (23.3±4.7 Gt/yr2 versus a total acceleration of
29.7±1.3 Gt/yr2 ) during 2003-2012."

Agrees with Enderlin(2014) doi:10.1002/2013GL059010 in that SMB dominates
linear term, but they have shown it dominates quadrature (acceleration)
term as well. Interesting that they see little regional acceleration
in NEGIS, contrary to Khan(2014) doi:10.1038/nclimate2161

Also of note:

"The signal from the Canadian GIC, which was removed from the
Greenland signal, corresponds to a mass loss of 74±7 Gt/yr with an
acceleration in loss of 10±2 Gt/yr2"

sidd

[sidd]

http://www.the-cryosphere-discuss.net/8/5485/2014/tcd-8-5485-2014.html

I think this paper is important, incomplete though it may be. The comment on the paper is worth reading, found under the  "Discussion" tab. Estimates latent heat flow from water/ice change in firn on transect 100 Km N of JI, but results may apply to rest of ice sheet. Large movement of heat via refreezing in upper part of Greenland, even at 1500m.

Read all about it, open source

sidd

[Tor Bejnar]

http://www.climatecentral.org/news/surprise-lake-sheds-light-on-underbelly-of-greenland-ice-18580
Surprise Lake Sheds Light on Underbelly of Greenland Ice

Such lakes of water pool at the bottom of an ice sheet or glacier, and were known to be scattered under parts of Antarctica. But they hadn’t been found yet in Greenland.

“The lake underneath the ice went away and the ice surface dropped to fill that space,” Willis said.

Since then, remote observations show the surface depression has been rising, in part from surface meltwater flowing back into the lake and raising the ice. The major melting across the whole surface of the ice sheet in the record warm summer of 2012 caused enough water to drain down that the ice surface went “rocketing up” as much as 40 centimeters per day, study co-author Robin Bell, a climate researcher at Columbia University’s Lamont-Doherty Earth Observatory, said.

“They show clearly that . . . the surface melt must have contributed to the rapid rise, the refilling of the subglacial lake,” Joe MacGregor, a glaciologist from the University of Texas, who was not involved in the research, said. “No one’s shown that before.”

[Gray-Wolf]

http://onlinelibrary.wiley.com/doi/10.1002/2014GL062255/abstract

and this from ;  http://www.truthdig.com/report/item/arctic_glaciers_galloping_melt_baffles_scientists_20150131?

"An ice cap in the high Arctic has lost what British scientists say is a significant amount of ice in an unusually short time.

It has thinned by more than 50 metres since 2012—about one sixth of its original thickness—and the ice flow is now 25 times faster, accelerating to speeds of several kilometres per year.

Over the last two decades, thinning of the Austfonna ice cap in the Svalbard archipelago—roughly half way between Norway and the North Pole—has spread more than 50km inland, to within 10km of the summit."

I have always worried that the melt warming brings with it will not be a 'drip,drip affair but a far more dynamic process showing periods of rapid Sea level rises from 'melt water pulses' as both Greenland and Antarctica show similar catastrophic decays as Austfonna?

[Wipneus]

G-W, this was noticed before on the forum:
https://forum.arctic-sea-ice.net/index.php/topic,416.msg42652.html#msg42652
https://forum.arctic-sea-ice.net/index.php/topic,596.msg43943.html#msg43943

Further, the surging glaciers are not that special, maybe even common for Svalbard.

http://www.svalbardglaciers.org/surging_glaciers.html
http://www.svalbardglaciers.org/surging_glaciers_other_glaciers.html

Basin 3 Austfonna
Austfonna Basin 3 2009 Initial crevasing due to surge
Basin 3 Austfonna 2009, initial creassing on an elevated ridge due to surge                                Photo: M. Sund

The surge of Basin 3 corresponds well to Solheim’s (1991) calculation of the basin’s surge cycle of 130-140 years, which is shorter than that of Bråsvellbreen estimated to more than 500 years. The variation stem from differences in the size of the accumulation area.