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

[Gray-Wolf]

Best remember that some of those marine terminating glaciers also drain the ice sheet? As they rettreat, and are undercut by seawater, they will end up allowing the ocean into the basin under the ice sheet beyond?

The erosion of the sheet from below, and subsequent collapses, lead to elevation changes that surface ablation alone could not hope to match?

Once the valleys drop into the melt zone then we see rapid losses of the ice rubble below and collapses of the ice cliffs to the sides. These collapses are then melted/transported to the sea to melt and the process continues.

With such thick ice you can see the issue of it falling into the melt zone (or the meltzone racing up to meet the surface??) but the inundation of the basin beyond is something to fret over (IMHO) esp. the rate Petermann is retreating up valley?

[knocker]

Nothing that we didn't know already but an article today in The Columbus Dispatch

 

Tracking Greenland’s fast-melting ice sheets

http://www.dispatch.com/content/stories/science/2013/04/21/tracking-greenlands-fast-melting-ice-sheets.html?fb_action_ids=10200462502318533&fb_action_types=og.recommends&fb_source=other_multiline&action_object_map=%255B542792865771542%255D&action_type_map=%255B%2522og.recommends%2522%255D&action_ref_map=%255B%255D

[Gray-Wolf]

With the ice sheet well soaked in mobile melt waters at depth I've been keeping my eyes on possible 'avalanche' style snow slides. At present there is some discussion about 'crevasses' across the ice sheet and i'm looking into a stange 'fan shape at the bottom of the ice sheet along the Central eastern coastal strip (like a giant 'mudslide' of snow?)

 

I'll keep folk updated and provide images when I find them.

[knocker]

Rapid loss of firn pore space accelerates 21st century Greenland mass loss^†

Abstract

[1] Mass loss from the two major ice sheets and their contribution to global sea level rise is accelerating. In Antarctica, mass loss is dominated by increased flow velocities of outlet glaciers, following the thinning or disintegration of coastal ice shelves into which they flow. In contrast, ~55% of post-1992 Greenland ice sheet (GrIS) mass loss is accounted for by surface processes, notably increased meltwater runoff. A ~subtle process in the surface mass balance of the GrIS is the retention and refreezing of meltwater, currently preventing ~40% of the meltwater to reach the ocean. Here we force a high-resolution atmosphere/snow model with a mid-range warming scenario (RCP4.5, 1970–2100), to show that rapid loss of firn pore space, by >50% at the end of the 21st century, quickly reduces this refreezing buffer. As a result, GrIS surface mass loss accelerates throughout the 21st century and its contribution to global sea level rise increases to 1.7±0.5 mm yr^−1, more than four times the current value.

 

 

http://onlinelibrary.wiley.com/doi/10.1002/grl.50490/abstract

Edited April 28, 2013 by knocker

[Gray-Wolf]

It's like our moor can be a great damper from heavy rain events but, once saturated, it can also mean greater floods are possible (as we saw last summer).

 

The buried snow acts like a sponge 'mopping up' the surface melt but there is a break point where the sponge is full and the chracter of the snow below acts in a different way to what we are accustomed to seeing?

 

At the end of the day this may well be an important mechanism in the rapid decay of ice sheets?

[knocker]

Which ever way you look at GW it's not looking good.

[Gray-Wolf]

In previous warmings we would be looking at the West Antarctic Ice sheet and having this discussion? If Greenland has us concerned then what will prospects appear like when W.A.I.S. is also back to lead the mass loss tables? (as the Ozone Forcing drops out and world warmth re-enters the Southern Continent.)

 

Folk have taken advantage of the slow response of the planet to warming as a sign of 'no warming'. They neglected to look into paleo climates and periods where change was instant (decadal) when they engaged on this tactic. I believe this will be back to bite them in the Butt as AGW forces 'natural' responses, that are far faster than GHG  forcings, to unfurl across the globe with Albedo flip being the first and Methane destabilisation hard on it's heels?

Edited April 28, 2013 by Gray-Wolf

[knocker]

Greenland “snow drought†makes big 2013 melt more likely

http://www.meltfactor.org/blog/?p=860

Edited May 4, 2013 by knocker

[Gray-Wolf]

Not good. Less snow means we get to the 'dark layer' a lot quicker and eat into the pack faster (further darkening the snow). If we see the Anomalous high set up over Southern Greenland then the folk touting lasts years 97% surface melt as 'freak' or '164yr cycle' will have to have a re-think (IMHO).

[john pike]

The algorithm for the Greenland Ice Sheet Today daily melt extent has been revised to account for unusually warm winter snow layers and residual meltwater deep in the snow. Meltwater from last summer’s intense melt season did not completely re-freeze through at least mid December. The adjusted algorithm shows greatly reduced melt extent for early 2013. This much lower extent is more consistent with available weather and climate records.

 

 

before after

 

http://nsidc.org/greenland-today/2013/03/an-early-spring-calibration-for-melt-detection/

Edited May 4, 2013 by john pike

[Methuselah]

Tbh, I don't know what Greenland's long-term future is... 

[Gray-Wolf]

I think we can safely say that in the short term continued mass loss and Albedo drop is pretty 'nailed on' though Pete?

 

I have to wonder how this 'storage' of melt in the pack below the surface will pan out? Surely there comes a point where the snow is saturated? How does this extra load impact slope stability and will it possibly lead to rapid mass loss/sea level hikes when it works it's way seaward? We have seen mass loss double over the period of storage so what rate is Greenland melting? Should we be looking at last years 'record melt' as needing upward revision to account for the melt still 'in pack'

[knocker]

Puisortoq North Glacier southeast Greenland has experienced an increased rate of retreat since 2000. The retreat is expanding a fjord that begins just north of the Puisortoq Peninsula and west of the Otte Rud Island

 

Dynamics Group, at Ohio State University Howat and Eddy (2011) observed the glacier retreat as 20 m in the 1990′s and 2 kilometers from 2000-2010. Of the 90 glaciers in southeast Greenland examined, 90% retreated, with an average rate of 107 meters per year from 2000 to 2010.

 

http://glacierchange.wordpress.com/2013/05/08/puisortoq-north-glacier-retreat-southeast-greenland/?utm_source=dlvr.it&utm_medium=twitter

[Methuselah]

I think we can safely say that in the short term continued mass loss and Albedo drop is pretty 'nailed on' though Pete?

 

I have to wonder how this 'storage' of melt in the pack below the surface will pan out? Surely there comes a point where the snow is saturated? How does this extra load impact slope stability and will it possibly lead to rapid mass loss/sea level hikes when it works it's way seaward? We have seen mass loss double over the period of storage so what rate is Greenland melting? Should we be looking at last years 'record melt' as needing upward revision to account for the melt still 'in pack'

Sad to say it, Ian mate, but neither can I...But one thing I enjoy about science, is that its reach only extends so far. Yes, all other things remaining equal, a step change of some sort, in the Arctic is inevitable; and, given that CO2 is hardly likely to conveniently alter its absorption spectrum, any time soon, we have to hope that something unforeseen occurs...

[Gray-Wolf]

Agreed Pete but the 'track record' through past warmings doesn't instill one with confidence? When we are expected to see the Continent as Green and hospitable, post some 'roman/dark age/middle age' warming then we should also expect our current temps (higher than any time in the past few thousand years?) to turn the south of Greenland into a farmers dream???

 

I Jest! Once current warming fully impacts Greenland though we should have much better data on which to view the claims of Erik and his household....if not by better Archaeology of their settlements?

[knocker]

The effect of climate change on iceberg production by Greenland glaciers

While the impact of climate change on the surface of the Greenland ice sheet has been widely studied, a clear understanding of the key process of iceberg production has eluded researchers for many years. Published in Nature this week, a new study presents a sophisticated computer model that provides a fresh insight into the impact of climate change on the production of icebergs by Greenland glaciers, and reveals that the shape of the ground beneath the ice has a strong effect on its movement.

 

Over the past decade, ice-loss from the Greenland Ice Sheet has been accelerating, raising concerns about runaway losses and consequent sea-level rise. But research into the four major Greenland fast-flowing glaciers has enabled scientists to show that while these glaciers may show several bursts of retreat and periods of high iceberg formation in future, the rapid acceleration seen in recent years is unlikely to continue unchecked.

 

This is a crucial step forward in understanding how Greenland's glaciers will contribute to sea-level rise in the future and indicates, say the scientists, how important a more detailed knowledge of such glaciers is. The scientists first investigated the current behaviour of the four glaciers and found that the rate at which they lose ice

depends critically on the shape of the fjords in which they sit, and the topography of the rock below them.

 

A computer model for fast-flowing outlet glaciers was then specifically designed from their investigations. It gave a projected sea-level-rise contribution from these glaciers of 2cm to 5cm by the year 2200, which is lower than estimates based solely on the extrapolation of current trends.

 

 

http://www.eurekalert.org/pub_releases/2013-05/bas-teo050813.php

[BornFromTheVoid]

A great new site that collects satellite data for subsets of Greenland and Antarctica, allows you to enlarge and download the imagery too.

 

I think this will be very handy watching the Greenland melt this summer

http://rapidice.org/viewer/

 

What is RISCO?

The Rapid Ice Sheet Change Observatory (RISCO) is a NASA-funded, inter-organizational collaboration created to provide a systematic framework for gathering, processing, analyzing, and distributing consistent satellite imagery of polar ice sheet change. RISCO gathers observations over areas of rapid change and makes them easily accessible to investigators, media, and general public. As opposed to existing data centers, which are structured to archive and distribute diverse types of raw data to end users with the specialized software and skills to analyze them, RISCO distributes processed georeferenced raster image data products in JPEG and GeoTIFF formats, making them immediately viewable with commonly available software.

 

What imagery data is available?

These datasets include a growing library (290,000 images and counting...) of archived and newly-acquired imagery from a wide constellation of satellites and airborne sensors collected as part of NASA's Operation IceBridge.  You can find a list of current datasets here (http://www.rapidice.org/data).  Very high-resolution sensors such as WorldView-1 and QuickBird-2 do not include georeferencing information due to licensing restrictions but can be requested by U.S. federally funded researchers.

 

What’s the web application all about?

Data are viewable and downloadable through the RapidIceViewer (http://www.rapidice.org/viewer) a JavaScript-based interactive portal. Images and other data sets for specific areas-of-interest (“subsetsâ€) are organized by time with filter options. Images can also be stacked to make on-the-fly animations. We urge you to explore the vast amount of historical and current images in your area-of-interest!

 

 

 

[ANYWEATHER]

A great new site that collects satellite data for subsets of Greenland and Antarctica, allows you to enlarge and download the imagery too.

I think this will be very handy watching the Greenland melt this summer

http://rapidice.org/viewer/

l think you may be dissapointed bftv, but anyway good luck Edited May 8, 2013 by ANYWEATHER

[BornFromTheVoid]

l think you may be dissapointed bftv, but anyway good luck

 

I may be disappointed about what?

[ANYWEATHER]

I may be disappointed about what?

Sorry on my tablet, but im collecting some info in the near future..

[Gray-Wolf]

Found this of interest over on Neven's blog;

 

 

I talk seldom as I find it today counter-productive to publish things and work with decision-makers at UN, EU & UK. Yet, I felt it necessary to write a note on this matter as I was nominated back in 2008 for international Nanak Peace Prize (sea level rise risks for global security and economic stability).

Firstly, the Negative Arctic Oscillations will continue and intensify much like sea ice will diminish and the snow line retreat will head to the north earlier than before. Almost each year from now on will show some sort of advance in melting (snow, sea ice, tundra or sea bed) to the previous years. Storms will be fiercer.

Secondly, the metamorphosis of Greenland's cold, dry, stable and moraine-forming ice sheet into warm, wet, dynamic and aggregate-forming ice sheet when summers will see Greenland surrounded by ice-free oceans.

The melt water from the surface percolates to the ice sheet base and transforms it into honeycombed, water-clogged ice that is slushy and unable to withstand pressure of the overlying ice layers. This eventually leads to Larsen B style rapid ice sheet failure as watery base oozes its way out and the overlying colder and dryer ice fractures forming huge ice islands. Heindrich Minus One (H-1) Ice Berg Calving then results, with the associated Last Dryas cooling as the ocean basin between America and Europe fills with ice debris.

Thirdly, the transformation of dominance of the "seasonal impact" moulins/crevasses into "accumulative impact" moulins and crevasses.

Until recently the ice melting occurred on the perimeter of Greenland where melt water and ice drains into ocean by the early autumn and takes the heat (thermal inertia of melt water) with it.

Although Jason Box criticised me that there exist no "accumulative impact" moulins on top of Greenland interior, I was able to find 29 sites that year in aerial survey.

Ice sheet is highly insular material and when melt water falls deep into ice, no heat can escape to the surface. As each summer adds water in subglacial ponds, or crevasses within ice, there is an absolute greenhouse effect in action with 100% retention of summertime heat stored by melt water and ice (if surface water re-freezes within ice crevasses at the end of season).

Accumulative impact moulins sit on ice sheet where subglacial ground inclination is inward, thus taking the melt water ever deeper into ice. Although some water re-freezes in crevasses to form those blue bands (occasionally seen in the ice bergs), the thermal inertia is absorbed by the surrounding ice matrix which warms.

Each subsequent summer see the energy required for melting decreased and in many cases there are growing liquid water pockets at the base of the ice sheet. At the end of this process, after just a decade of seriously warm post-sea ice summers, the ice is so honeycombed and soft that it cannot withstand overlying layers. The harder ice sheet surface caves in while the highly pressured slushy ice and water come out. This then triggers a rapid sea level jump, Heindrich (H-1) ice debris event and the Last Dryas.

Fourthly, the large supply of water triggers three rapid erosion forces. Those of cavitation, plucking and kolking and where the ice sheet edge meets ocean, the turbidic mud flows and rock falls like in Melville Bay. This region then rapidly subsides in a Storegga-slide style event pushed by the large ice islands launched to sea and the high pressure water jets that cause the three rapid erosion forces.

Besides ice free Arctic Ocean, the methane infested Arctic air will trap sun's energy far more effectively that it is still doing today. None of these things should surprise us.

Posted by: Veli Kallio | May 12, 2013 at 05:24

 

When we try to imagine the water filled slush below Greenland's surface ice this provides an interesting look at how it all hangs together? There must come a point where this unique forcing provides the means for a rapid collapse of portions of the ice sheet and , should we see an ice strewn Atlantic, a chilly medium term future for us here in the UK (will we still have folk complaining of global cooling as the massive ice sheet disintegrates before their eyes due to a down turn in UK temps?)

[be cause]

>>>No .GW  .we would just be complaining about the destruction of  the economies of western Europe and NE America  .. if our governments hadn't done it already !!

[Gray-Wolf]

So what does happen to the global futures market when climate extremes can be expected to take their toll? What happens once the traders care to look up from the screens and contemplate what the rapidly changing global climate means to global economies?

[be cause]

That's a multi-Trillion dollar question

[knocker]

Video

 

Greenland ice sheet reflectivity has declined substantially in the 13 years in response to anomalous weather patterns and climate warming. The video features data from NASA satellite sensors that begin in year 2000. This presentation is to accompany a published a scientific analysis of the past 12 years of Greenland ice reflectivity...

 

Box, J. E., Fettweis, X., Stroeve, J. C., Tedesco, M., Hall, D. K., and Steffen, K.: Greenland ice sheet albedo feedback: thermodynamics and atmospheric drivers, The Cryosphere Discuss., 6, 593-634, doi:10.5194/tcd-6-593-2012, 2012.

Jason E. Box, PhD

 

Assoc. Prof., Department of Geography, Byrd Polar Research Center
The Ohio State University, Columbus, Ohio, USA
 

bprc.osu.edu/~jbox/

 

 

http://vimeo.com/46938581

Edited May 15, 2013 by knocker