Greenland - What Do We Know, What Is The Long Term Future And Is There Any Evidence Of A Melt Out?

[Interitus]

Not strictly related to Greenland's state or long term change, but something moderately interesting happening currently as visible from the MODIS satellites over the last few days.

The area in question is in the far northeast, centred on Astrup Fjord which is a small inlet on the southern side of Independence Fjord which is the large stretch of water across the upper part of the images, with Hagen Fjord branching off to the east on the right hand side. As can be seen a week ago, the first snows had settled over much of the area apart from some of the lowest ground, but with only very scattered ice floes, refreeze had not yet started and it is a fairly innocuous scene -

https://earthdata.nasa.gov/labs/worldview/?p=arctic&l=MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_Bands721(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,MODIS_Terra_CorrectedReflectance_Bands367(hidden),MODIS_Terra_CorrectedReflectance_Bands721(hidden),Graticule,Coastlines&t=2015-09-02&v=152523.65577353298,-884206.6790305657,327371.655773533,-801902.6790305657

 

The next few days are mostly cloudy though five days later even the lower parts had a dusting of snow, but noticeable now is a large sedimentary flow filling Astrup Fjord and spreading into Independence Fjord - 

https://earthdata.nasa.gov/labs/worldview/?p=arctic&l=MODIS_Aqua_CorrectedReflectance_TrueColor,MODIS_Aqua_CorrectedReflectance_Bands721(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,MODIS_Terra_CorrectedReflectance_Bands367(hidden),MODIS_Terra_CorrectedReflectance_Bands721(hidden),Graticule,Coastlines&t=2015-09-07&v=152523.65577353298,-884206.6790305657,327371.655773533,-801902.6790305657

https://earthdata.nasa.gov/labs/worldview/?p=arctic&l=MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_Bands721(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,MODIS_Terra_CorrectedReflectance_Bands367(hidden),MODIS_Terra_CorrectedReflectance_Bands721(hidden),Graticule,Coastlines&t=2015-09-07&v=152523.65577353298,-884206.6790305657,327371.655773533,-801902.6790305657

 

The next day, the 8th, is not very clear, but the sediment cloud appears to have spread further into Independence Fjord -

https://earthdata.nasa.gov/labs/worldview/?p=arctic&l=MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_Bands721(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,MODIS_Terra_CorrectedReflectance_Bands367(hidden),MODIS_Terra_CorrectedReflectance_Bands721(hidden),Graticule,Coastlines&t=2015-09-08&v=152523.65577353298,-884206.6790305657,327371.655773533,-801902.6790305657

 

This is confirmed the following day (yesterday), accompanied by a fresh surge of sediment -

https://earthdata.nasa.gov/labs/worldview/?p=arctic&l=MODIS_Aqua_CorrectedReflectance_TrueColor,MODIS_Aqua_CorrectedReflectance_Bands721(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,MODIS_Terra_CorrectedReflectance_Bands367(hidden),MODIS_Terra_CorrectedReflectance_Bands721(hidden),Graticule,Coastlines&t=2015-09-09&v=152523.65577353298,-884206.6790305657,327371.655773533,-801902.6790305657

https://earthdata.nasa.gov/labs/worldview/?p=arctic&l=MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_Bands721(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,MODIS_Terra_CorrectedReflectance_Bands367(hidden),MODIS_Terra_CorrectedReflectance_Bands721(hidden),Graticule,Coastlines&t=2015-09-09&v=152523.65577353298,-884206.6790305657,327371.655773533,-801902.6790305657

 

And the images from today show no let up in the cloud production, covering a couple of hundred square miles, though how long this is visible may be limited with refreezing apparent now -

https://earthdata.nasa.gov/labs/worldview/?p=arctic&l=MODIS_Aqua_CorrectedReflectance_TrueColor,MODIS_Aqua_CorrectedReflectance_Bands721(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,MODIS_Terra_CorrectedReflectance_Bands367(hidden),MODIS_Terra_CorrectedReflectance_Bands721(hidden),Graticule,Coastlines&t=2015-09-10&v=152523.65577353298,-884206.6790305657,327371.655773533,-801902.6790305657

https://earthdata.nasa.gov/labs/worldview/?p=arctic&l=MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_Bands721(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,MODIS_Terra_CorrectedReflectance_Bands367(hidden),MODIS_Terra_CorrectedReflectance_Bands721(hidden),Graticule,Coastlines&t=2015-09-10&v=152523.65577353298,-884206.6790305657,327371.655773533,-801902.6790305657

[Gray-Wolf]

Thanks for this Int.! I've put some feelers out to see if anyone can piece together the 'event'.

[BornFromTheVoid]

My guess is that you've just spotted a glacial outburst flood. 

 

There was probably a chamber holding meltwater under the glacier nearby. Either the barrier keeping it in broke down or melted, or the pressure built up and simply broke though causing the large discharge. This kinds of flood are commonplace in Iceland, Alaska and mountainous glaciated regions.

[Interitus]

My guess is that you've just spotted a glacial outburst flood. 

 

There was probably a chamber holding meltwater under the glacier nearby. Either the barrier keeping it in broke down or melted, or the pressure built up and simply broke though causing the large discharge. This kinds of flood are commonplace in Iceland, Alaska and mountainous glaciated regions.

 

Yes, something along these lines is most probable, but as this nice landsat image shows in detail not apparent in the MODIS http://blog.imagico.de/wp-content/uploads/2014/08/egreenland_crop5.ann_.jpg the question is whether it emanated directly from one of the outlets of the Hugh Lee Gletscher overlooking Astrup Fjord to the east, or possibly was there a breach from the chain of proglacial lakes in the valley?

 

Certainly, northeastern Greenland in particular has experienced high levels of melting this summer which may have prompted this event 

Edited September 11, 2015 by Interitus

[knocker]

What Darkens the Greenland Ice Sheet?

https://eos.org/opinions/what-darkens-the-greenland-ice-sheet

[stewfox]

Yes, something along these lines is most probable, but as this nice landsat image shows in detail not apparent in the MODIS http://blog.imagico.de/wp-content/uploads/2014/08/egreenland_crop5.ann_.jpg the question is whether it emanated directly from one of the outlets of the Hugh Lee Gletscher overlooking Astrup Fjord to the east, or possibly was there a breach from the chain of proglacial lakes in the valley?

 

Certainly, northeastern Greenland in particular has experienced high levels of melting this summer which may have prompted this event 

 

i

Interesting to see continued surface melt in the far north so late in the season

[Interitus]

i

Interesting to see continued surface melt in the far north so late in the season

Hmm, I have my doubts that is accurate, judging by the temperatures in the region. On the 23rd the maximum from Ogimet at Henrik Kroeyer Holme was -8.3°C, Nord AWS was -10.4°C, and -11.4°C at Kap Morris Jesup and at Alert on neighbouring Ellesmere Island. Theoretically possible that these low lying locations lay under an inversion but the Meteociel GFS charts had 850mb temperatures around -16°C and the two radiosonde ascents at Alert showed nothing above -10.7°C.

The sun is very weak now of course and it appeared to be mostly cloudy in any case which also reduces the likelihood that there was some dramatic localised fohn effect.

[knocker]

Subglacial lake drainage detected beneath the Greenland ice sheet

 

The contribution of the Greenland ice sheet to sea-level rise has accelerated in recent decades. Subglacial lake drainage events can induce an ice sheet dynamic response—a process that has been observed in Antarctica, but not yet in Greenland, where the presence of subglacial lakes has only recently been discovered. Here we investigate the water flow paths from a subglacial lake, which drained beneath the Greenland ice sheet in 2011. Our observations suggest that the lake was fed by surface meltwater flowing down a nearby moulin, and that the draining water reached the ice margin via a subglacial tunnel. Interferometric synthetic aperture radar-derived measurements of ice surface motion acquired in 1995 suggest that a similar event may have occurred 16 years earlier, and we propose that, as the climate warms, increasing volumes of surface meltwater routed to the bed will cause such events to become more common in the future.

 

http://www.nature.com/ncomms/2015/151009/ncomms9408/full/ncomms9408.html

 

Brief press release

 

http://www.sciencedaily.com/releases/2015/10/151009083035.htm

[Interitus]

 

Interesting to see continued surface melt in the far north so late in the season

 

Duh, we should've read the 'About these images' section -

 

Note that the northeast coast (northern Peary Land and Kronprince Christian Land) is showing erroneous melt pixels. This is a false melt signal from seasonal snow and patchy ice areas, where our method of determining surface melting does not work. This issue does not affect trends for the entire ice sheet. We are working to improve the ice sheet mask.

[stewfox]

 

Duh, we should've read the 'About these images' section -

 

Note that the northeast coast (northern Peary Land and Kronprince Christian Land) is showing erroneous melt pixels. This is a false melt signal from seasonal snow and patchy ice areas, where our method of determining surface melting does not work. This issue does not affect trends for the entire ice sheet. We are working to improve the ice sheet mask.

 

We can see the 'melt'still going on at a pace  . Does make one question the overall validity of the data supplied for Greenland if seasonal snow and patchy ice areas give 'false data' , whey not for the entire ice sheet ?

Edited October 10, 2015 by stewfox

[Interitus]

Yes very long melt season this year!

it's poor, would take very little effort to correct these images for the web - maybe being overly honest, we would be none the wiser.

[stewfox]

Yes very long melt season this year!

it's poor, would take very little effort to correct these images for the web - maybe being overly honest, we would be none the wiser.

 

It puts into question the whole summer analysis if false data from the north has been acknowledged.

 

"""broad areas of the far northern ice sheet and the northwestern Melville Coast experienced frequent surface melting""

 

we now know may not be true

 

http://nsidc.org/greenland-today/

Edited October 10, 2015 by stewfox

[Gray-Wolf]

http://m.dailykos.com/story/2015/09/22/1421761/-Sudden-drainage-via-massive-chasm-of-Subglacial-lakes-in-Greenland-described-as-catastrophic

 

One of my personal fears is the rush of heat into the ice sheet over the past 15yrs. Has this now begun it travel inland allowing such 'multidecadal' features to fail further adding to the destabilisation of the inner ice?

[knocker]

Elevation change of the Greenland ice sheet due to surface mass balance and firn processes, 1960–2013

Quote

 

Abstract. Observed changes in the surface elevation of the Greenland ice sheet are caused by ice dynamics, basal elevation change, surface mass balance (SMB) variability, and by compaction of the overlying firn. The latter two contributions are quantified here using a firn model that includes compaction, meltwater percolation, and refreezing. The model is forced with surface mass fluxes and temperature from a regional climate model for the period 1960–2013. The model results agree with observations of surface density, density profiles from 62 firn cores, and altimetric observations from regions where ice-dynamical surface height changes are likely small. We find that the firn layer in the high interior is generally thickening slowly (1–5 cm yr^−1). In the percolation and ablation areas, firn and SMB processes account for a surface elevation lowering of up to 20–50 cm yr^−1. Most of this firn-induced marginal thinning is caused by an increase in melt since the mid-1990s, and partly compensated by an increase in the accumulation of fresh snow around most of the ice sheet. The total firn and ice volume change between 1980 and 2013 is estimated at −3900 ± 1030 km³ due to firn and SMB, corresponding to an ice-sheet average thinning of 2.32 ± 0.61 m. Most of this volume decrease occurred after 1995. The computed changes in surface elevation can be used to partition altimetrically observed volume change into surface mass balance and ice-dynamically related mass changes.

 

http://www.the-cryos...-3541-2015.html

Edited October 22, 2015 by knocker

[knocker]

Quiet weather in Greenland this week

 

http://polarportal.dk/en/groenlands-indlandsis/nbsp/isens-overflade/

Edited October 23, 2015 by knocker

[knocker]

Greenland Is Melting Away ( nice article)

 

http://www.nytimes.com/interactive/2015/10/27/world/greenland-is-melting-away.html

Edited October 27, 2015 by knocker

[knocker]

Despite Warming, Landsat Reveals Decadal Slowdowns on Greenland Ice Sheet

 

 

Oct 28, 2015 • Ice sheets are in perpetual motion, making their way downslope like a river. If the amount of snow that an ice sheet accumulates does not keep pace with its loss to the sea, sea level will rise. As temperatures have climbed, positive feedback loops have led to an accelerated loss of ice sheet sections that touch the sea, but in an unexpected twist to the global warming saga, scientists have just discovered a negative feedback loop that is slowing down the Greenland Ice Sheet sections that end on land—a sliver of good news for sea-level rise.

This discovery will be published in Nature on Oct. 29, 2015. “Our latest results show that a large sector of the Greenland Ice Sheet which terminates on land has slowed down during the last decade—during a period of sustained warming. This suggests that further increases in melting will not cause these land-terminating margins of the ice sheet to speed up,†explained lead author Andrew Tedstone, a glaciologist at the University of Edinburgh.

 

http://landsat.gsfc.nasa.gov/?p=11129

[knocker]

2015 melt season in review

 

Melt extent in Greenland was above average in 2015, ranking 11th highest in the 37 year record from satellite data. Overall, climate patterns favored intense melting in the north and northwestern parts of the ice sheet, and relatively cool conditions in the southeast.

 

http://nsidc.org/greenland-today/2015/11/2015-melt-season-in-review/

[stewfox]

2015 melt season in review

 

http://nsidc.org/greenland-today/2015/11/2015-melt-season-in-review/

 

 

 

A fairly average melt season so no evidence yet of any increase melt out. It will be interesting to see what  the next 20/30yrs bring

Edited November 7, 2015 by stewfox

[knocker]

Fast retreat of Zachariæ Isstrøm, northeast Greenland

 

After 8 years of decay of its ice shelf, Zachariæ Isstrøm, a major glacier of northeast Greenland that holds a 0.5-meter sea-level rise equivalent, entered a phase of accelerated retreat in fall 2012. The acceleration rate of its ice velocity tripled, melting of its residual ice shelf and thinning of its grounded portion doubled, and calving is now occurring at its grounding line. Warmer air and ocean temperatures have caused the glacier to detach from a stabilizing sill and retreat rapidly along a downward-sloping, marine-based bed. Its equal-ice-volume neighbor, Nioghalvfjerdsfjorden, is also melting rapidly but retreating slowly along an upward-sloping bed. The destabilization of this marine-based sector will increase sea-level rise from the Greenland Ice Sheet for decades to come.

 

http://www.sciencemag.org/content/early/2015/11/11/science.aac7111.full

[knocker]

More on the above

 

International effort reveals Greenland Ice Loss

 

http://www.esa.int/Our_Activities/Observing_the_Earth/Copernicus/Sentinel-1/International_effort_reveals_Greenland_ice_loss

[knocker]

Just released. Join Sofia Ribeiro on field work at the remote Station North.

 

http://tinyurl.com/oyhrbct 

[knocker]

Greenland Fjord Going Ice Free

Quote

At the AGU 2015 meeting a clear change from 15 years ago is the interdisciplinary nature of most research featured in most sessions.  In the glacier sessions there is physical oceanography, biology, climatology etc.to add in.  I will examine a SW Greenland Fjord, Alangordlia to illustrate this.  In 1987 Landsat image there are four glaciers reaching tidewater in the fjord and two significant glacial fed streams contributing plumes of sediment. By 2015 two of the glaciers, green arrow and pink arrow, have retreated from contact with the fjord. The glacier at the yellow arrow will lose contact with the fjord quite soon, and the glacier at the red arrow has reduced width of contact and will retreat from the fjord in the near future. A closeup using Google Earth from 2010 illustrates the terminus of each glacier, below.

 

[knocker]

Spatial+temporal dist of mass loss from Greenland Ice Sheet since 1900 w aerial imagery+geomorph Kjeldsen Nature http://dx.doi.org/10.1038/nature16183 …

Quote

The response of the Greenland Ice Sheet (GIS) to changes in temperature during the twentieth century remains contentious¹, largely owing to difficulties in estimating the spatial and temporal distribution of ice mass changes before 1992, when Greenland-wide observations first became available². The only previous estimates of change during the twentieth century are based on empirical modelling^{3, 4, 5} and energy balance modelling^{6, 7}. Consequently, no observation-based estimates of the contribution from the GIS to the global-mean sea level budget before 1990 are included in the Fifth Assessment Report of the Intergovernmental Panel on Climate Change⁸. Here we calculate spatial ice mass loss around the entire GIS from 1900 to the present using aerial imagery from the 1980s. This allows accurate high-resolution mapping of geomorphic features related to the maximum extent of the GIS during the Little Ice Age⁹ at the end of the nineteenth century. We estimate the total ice mass loss and its spatial distribution for three periods: 1900–1983 (75.1 ± 29.4 gigatonnes per year), 1983–2003 (73.8 ± 40.5 gigatonnes per year), and 2003–2010 (186.4 ± 18.9 gigatonnes per year). Furthermore, using two surface mass balance models^{10, 11} we partition the mass balance into a term for surface mass balance (that is, total precipitation minus total sublimation minus runoff) and a dynamic term. We find that many areas currently undergoing change are identical to those that experienced considerable thinning throughout the twentieth century. We also reveal that the surface mass balance term shows a considerable decrease since 2003, whereas the dynamic term is constant over the past 110 years. Overall, our observation-based findings show that during the twentieth century the GIS contributed at least 25.0 ± 9.4 millimetres of global-mean sea level rise. Our result will help to close the twentieth-century sea level budget, which remains crucial for evaluating the reliability of models used to predict global sea level rise^{1, 8}.

 

[knocker]

New paper Greenland's melt reduces the ability to store more https://cires.colorado.edu/news/press/openwater-2/ …

A new study of snow and firn layers high on the Greenland ice sheet, published in Nature Climate Change, shows that recent atmospheric warming is changing the ability of near-surface firn layers to store meltwater, which can result in a faster release of runoff from the ice sheet.